Adverse effects of COVID-19 vaccines and measures to prevent them

Authors: Kenji Yamamoto Virol J. 2022; 19: 100. Published online 2022 Jun 5. doi: 10.1186/s12985-022-01831-0 PMCID: PMC9167431PMID: 35659687

Abstract

Recently, The Lancet published a study on the effectiveness of COVID-19 vaccines and the waning of immunity with time. The study showed that immune function among vaccinated individuals 8 months after the administration of two doses of COVID-19 vaccine was lower than that among the unvaccinated individuals. According to European Medicines Agency recommendations, frequent COVID-19 booster shots could adversely affect the immune response and may not be feasible. The decrease in immunity can be caused by several factors such as N1-methylpseudouridine, the spike protein, lipid nanoparticles, antibody-dependent enhancement, and the original antigenic stimulus. These clinical alterations may explain the association reported between COVID-19 vaccination and shingles. As a safety measure, further booster vaccinations should be discontinued. In addition, the date of vaccination should be recorded in the medical record of patients. Several practical measures to prevent a decrease in immunity have been reported. These include limiting the use of non-steroidal anti-inflammatory drugs, including acetaminophen to maintain deep body temperature, appropriate use of antibiotics, smoking cessation, stress control, and limiting the use of lipid emulsions, including propofol, which may cause perioperative immunosuppression. In conclusion, COVID-19 vaccination is a major risk factor for infections in critically ill patients.

COVID Vaccines Increase Adverse Events and Weaken The Immune System

The coronavirus disease (COVID-19) pandemic has led to the widespread use of genetic vaccines, including mRNA and viral vector vaccines. In addition, booster vaccines have been used, but their effectiveness against the highly mutated spike protein of Omicron strains is limited. Recently, The Lancet published a study on the effectiveness of COVID-19 vaccines and the waning of immunity with time [1]. The study showed that immune function among vaccinated individuals 8 months after the administration of two doses of COVID-19 vaccine was lower than that among unvaccinated individuals. These findings were more pronounced in older adults and individuals with pre-existing conditions. According to the European Medicines Agency’s recommendations, frequent COVID-19 booster shots could adversely affect the immune response and may not be feasible [2]. Several countries, including Israel, Chile, and Sweden, are offering the fourth dose to only older adults and other groups rather than to all individuals [3].

The decrease in immunity is caused by several factors. First, N1-methylpseudouridine is used as a substitute for uracil in the genetic code. The modified protein may induce the activation of regulatory T cells, resulting in decreased cellular immunity [4]. Thereby, the spike proteins do not immediately decay following the administration of mRNA vaccines. The spike proteins present on exosomes circulate throughout the body for more than 4 months [5]. In addition, in vivo studies have shown that lipid nanoparticles (LNPs) accumulate in the liver, spleen, adrenal glands, and ovaries [6], and that LNP-encapsulated mRNA is highly inflammatory [7]. Newly generated antibodies of the spike protein damage the cells and tissues that are primed to produce spike proteins [8], and vascular endothelial cells are damaged by spike proteins in the bloodstream [9]; this may damage the immune system organs such as the adrenal gland. Additionally, antibody-dependent enhancement may occur, wherein infection-enhancing antibodies attenuate the effect of neutralizing antibodies in preventing infection [10]. The original antigenic sin [11], that is, the residual immune memory of the Wuhan-type vaccine may prevent the vaccine from being sufficiently effective against variant strains. These mechanisms may also be involved in the exacerbation of COVID-19.

Some studies suggest a link between COVID-19 vaccines and reactivation of the virus that causes shingles [1213]. This condition is sometimes referred to as vaccine-acquired immunodeficiency syndrome [14]. Since December 2021, besides COVID-19, Department of Cardiovascular Surgery, Okamura Memorial Hospital, Shizuoka, Japan (hereinafter referred to as “the institute”) has encountered cases of infections that are difficult to control. For example, there were several cases of suspected infections due to inflammation after open-heart surgery, which could not be controlled even after several weeks of use of multiple antibiotics. The patients showed signs of being immunocompromised, and there were a few deaths. The risk of infection may increase. Various medical algorithms for evaluating postoperative prognosis may have to be revised in the future. The media have so far concealed the adverse events of vaccine administration, such as vaccine-induced immune thrombotic thrombocytopenia (VITT), owing to biased propaganda. The institute encounters many cases in which this cause is recognized. These situations have occurred in waves; however, they are yet to be resolved despite the measures implemented to routinely screen patients admitted for surgery for heparin-induced thrombocytopenia (HIT) antibodies. Four HIT antibody-positive cases have been confirmed at the institute since the start of vaccination; this frequency of HIT antibody-positive cases has rarely been observed before. Fatal cases due to VITT following the administration of COVID-19 vaccines have also been reported [15].

As a safety measure, further booster vaccinations should be discontinued. In addition, the date of vaccination and the time since the last vaccination should be recorded in the medical record of patients. Owing to the lack of awareness of this disease group among physicians and general public in Japan, a history of COVID-19 vaccination is often not documented, as it is in the case of influenza vaccination. The time elapsed since the last COVID-19 vaccination may need to be considered when invasive procedures are required. Several practical measures that can be implemented to prevent a decrease in immunity have been reported [16]. These include limiting the use of non-steroidal anti-inflammatory drugs, including acetaminophen, to maintain deep body temperature, appropriate use of antibiotics, smoking cessation, stress control, and limiting the use of lipid emulsions, including propofol, which may cause perioperative immunosuppression [17].

To date, when comparing the advantages and disadvantages of mRNA vaccines, vaccination has been commonly recommended. As the COVID-19 pandemic becomes better controlled, vaccine sequelae are likely to become more apparent. It has been hypothesized that there will be an increase in cardiovascular diseases, especially acute coronary syndromes, caused by the spike proteins in genetic vaccines [1819]. Besides the risk of infections owing to lowered immune functions, there is a possible risk of unknown organ damage caused by the vaccine that has remained hidden without apparent clinical presentations, mainly in the circulatory system. Therefore, careful risk assessments prior to surgery and invasive medical procedures are essential. Randomized controlled trials are further needed to confirm these clinical observations.

In conclusion, COVID-19 vaccination is a major risk factor for infections in critically ill patients.

References

1. Nordström P, Ballin M, Nordström A. Risk of infection, hospitalisation, and death up to 9 months after a second dose of COVID-19 vaccine: a retrospective, total population cohort study in Sweden. Lancet. 2022;399:814–823. doi: 10.1016/S0140-6736(22)00089-7. [PMC free article] [PubMed] [CrossRef] [Google Scholar]

2. European Centre for Disease Prevention and Control. Interim public health considerations for the provision of additional COVID-19 vaccine doses. https://www.ecdc.europa.eu/en/publications-data/covid-19-public-health-considerations-additional-vaccine-doses. Accessed 4 May 2022.

3. Mallapaty S. Fourth dose of COVID vaccine offers only slight boost against Omicron infection. Nature. 2022 doi: 10.1038/D41586-022-00486-9. [CrossRef] [Google Scholar]

4. Krienke C, Kolb L, Diken E, Streuber M, Kirchhoff S, Bukur T, et al. A noninflammatory mRNA vaccine for treatment of experimental autoimmune encephalomyelitis. Science. 2021;371:145–153. doi: 10.1126/science.aay3638. [PubMed] [CrossRef] [Google Scholar]

5. Bansal S, Perincheri S, Fleming T, Poulson C, Tiffany B, Bremner RM, et al. Cutting edge: circulating exosomes with COVID spike protein are induced by BNT162b2 (Pfizer–BioNTech) vaccination prior to development of antibodies: a novel mechanism for immune activation by mRNA vaccines. J Immunol. 2021;207:2405–2410. doi: 10.4049/jimmunol.2100637. [PubMed] [CrossRef] [Google Scholar]

6. BNT162b2 Module 2.4. Nonclinical Overview. FDA-CBER-2021-4379-0000681 JW-v-HHS-prod-3-02418.pdf (judicialwatch.org) Access 6 May 2022.

7. Ndeupen S, Qin Z, Jacobsen S, Bouteau A, Estanbouli H, Igyártó BZ. The mRNA-LNP platform’s lipid nanoparticle component used in preclinical vaccine studies is highly inflammatory. Science. 2021;24:103479. doi: 10.1016/j.isci.2021.103479. [PMC free article] [PubMed] [CrossRef] [Google Scholar]

8. Yamamoto K. Risk of heparinoid use in cosmetics and moisturizers in individuals vaccinated against severe acute respiratory syndrome coronavirus. Thromb J. 2021 doi: 10.1186/s12959-021-00320-8. [PMC free article] [PubMed] [CrossRef] [Google Scholar]

9. Lei Y, Zhang J, Schiavon CR, He M, Chen L, Shen H, et al. SARS-CoV-2 spike protein impairs endothelial function via downregulation of ACE 2. Circ Res. 2021;128:1323–1326. doi: 10.1161/CIRCRESAHA.121.318902. [PMC free article] [PubMed] [CrossRef] [Google Scholar]

10. Liu Y, Soh WT, Kishikawa JI, Hirose M, Nakayama EE, Li S, et al. An infectivity-enhancing site on the SARS-CoV-2 spike protein targeted by antibodies. Cell. 2021;184:3452–66.e18. doi: 10.1016/j.cell.2021.05.032. [PMC free article] [PubMed] [CrossRef] [Google Scholar]

11. Cho A, Muecksch F, Schaefer-Babajew D, Wang Z, Finkin S, Gaebler C, et al. Anti-SARS-CoV-2 receptor-binding domain antibody evolution after mRNA vaccination. Nature. 2021;600:517–522. doi: 10.1038/s41586-021-04060-7. [PMC free article] [PubMed] [CrossRef] [Google Scholar]

12. Desai HD, Sharma K, Shah A, Patoliya J, Patil A, Hooshanginezhad Z, et al. Can SARS-CoV-2 vaccine increase the risk of reactivation of Varicella zoster. Systematic review. J Cosmet Dermatol. 2021;20:3350–3361. doi: 10.1111/jocd.14521. [PMC free article] [PubMed] [CrossRef] [Google Scholar]

13. Barda N, Dagan N, Ben-Shlomo Y, Kepten E, Waxman J, Ohana R, et al. Safety of the BNT162b2 mRNA Covid-19 v in a nationwide setting. N Engl J Med. 2021;385:1078–1090. doi: 10.1056/NEJMOA2110475/SUPPL_FILE/NEJMOA2110475_DISCLOSURES.PDF. [PMC free article] [PubMed] [CrossRef] [Google Scholar]

14. Seneff S, Nigh G, Kyriakopoulos AM, McCullough PA. Innate immune suppression by SARS-CoV-2 mRNA vaccinations: the role of G-quadruplexes, exosomes, and MicroRNAs. Food Chem Toxicol. 2022;164:113008. doi: 10.1016/J.FCT.2022.113008. [PMC free article] [PubMed] [CrossRef] [Google Scholar]

15. Lee EJ, Cines DB, Gernsheimer T, Kessler C, Michel M, Tarantino MD, et al. Thrombocytopenia following Pfizer and Moderna SARS-CoV-2 vaccination. Am J Hematol. 2021;96:534–537. doi: 10.1002/AJH.26132. [PMC free article] [PubMed] [CrossRef] [Google Scholar]

16. Yamamoto K. Five important preventive measures against the exacerbation of coronavirus disease. Anaesthesiol Intensive Ther. 2021;53:358–359. doi: 10.5114/ait.2021.108581. [PubMed] [CrossRef] [Google Scholar]

17. Yamamoto K. Risk of propofol use for sedation in COVID-19 patient. Anaesthesiol Intensive Ther. 2020;52:354–355. doi: 10.5114/ait.2020.100477. [PubMed] [CrossRef] [Google Scholar]

18. Gundry SR. Observational findings of PULS cardiac test findings for inflammatory markers in patients receiving mRNA vaccines. Circulation. 2021;144(suppl_1):A10712–A10712. doi: 10.1161/circ.144.suppl_1.10712. [CrossRef] [Google Scholar]

19. Lai FTT, Li X, Peng K, Huang L, Ip P, Tong X, et al. Carditis After COVID-19 vaccination with a messenger RNA vaccine and an inactivated virus vaccine: a case-control study. Ann Intern Med. 2022;175:362–370. doi: 10.7326/M21-3700. [PMC free article] [PubMed] [CrossRef] [Google Scholar]

COVID‐19‐induced endotheliitis: emerging evidence and possible therapeutic strategies

Authors: Eleonora Calabretta, 1 , 12 Jose M. Moraleda, 2 Massimo Iacobelli, 3 Ruben Jara, 4 Israel Vlodavsky, 5 Peter O’Gorman, 6 Antonio Pagliuca, 7 Clifton Mo, 8 Rebecca M. Baron, 9 Alessio Aghemo, 10 , 12 Robert Soiffer, 8 Jawed Fareed, 11 Carmelo Carlo‐Stella, 1 , 12 , * and Paul Richardson 8 , *

Br J Haematol. 2021 Apr; 193(1): 43–51.Published online 2021 Feb 4.  doi:  10.1111/bjh.17240 PMCID:  PMC8014053PMID: 33538335

Introduction

The coronavirus disease 2019 (COVID‐19) pandemic, a viral illness caused by the severe acute respiratory syndrome coronavirus‐2 (SARS‐CoV‐2), 1 has produced at the time of this writing nearly 33 million cases of infection, with over a million deaths in 235 countries, 2 causing an unprecedented burden on healthcare systems and a severe global socioeconomic crisis. As the pandemic spreads, knowledge on the disease course, as well as potential risk factors and predictors of severity is increasing daily, and initial data from randomised controlled studies have allowed care providers to refine therapeutic strategies. Nonetheless, mortality is markedly elevated among those presenting with severe disease, long‐term sequelae among survivors are unknown, and vaccine‐based therapies currently remain at early stages of development.

Most reported cases are asymptomatic or present with mild symptoms; however, 7–26% of hospitalised patients experience severe disease, often requiring admission to intensive care units (ICUs), with progressive multiple organ dysfunction and high mortality. 3 Such differences in clinical outcomes have led physicians to initiate diverse pharmacological therapies at various stages of the disease, generating challenges as to the most appropriate therapeutic choice for COVID‐19. In this context, the use of dexamethasone has significantly reduced mortality rates in critically ill patients requiring supplemental oxygen or mechanical ventilation, 6 and remdesivir has demonstrated clinical benefit in hospitalised patients, but with unknown survival benefit to date 7 ; additional effective treatment options are therefore urgently needed.

In an initial attempt to provide a uniform and widely reproducible methodology to guide systematic treatment strategies, a three‐stage classification of COVID‐19 has been proposed. 8 The Stage I or ‘early infection’ occurs at the initial establishment of disease with high viral replication, and commonly presents with a range of complaints that can include mild and often non‐specific influenza‐like signs and symptoms. Stage II is the ‘pulmonary phase’, with preferential viral‐mediated injury of the lung parenchyma and this is characterised by shortness of breath, hypoxia and pulmonary infiltrates with some degree of lung inflammation. Stage III is characterised by an exaggerated host immune‐inflammatory response to the virus, leading to acute respiratory distress syndrome (ARDS) and multi‐organ failure (MOF).Go to:

Endothelial cells are a preferential target of COVID‐19 resulting in widespread endotheliitis

Emerging evidence suggests that endothelial damage and subsequent morphological and functional changes in the endothelium play important roles in COVID‐19‐induced hyperinflammation. The virus, which binds to the angiotensin‐converting enzyme 2 (ACE2) receptor, 9 displays a profound tropism for human lung and small intestine epithelium, as well as the vascular endothelium. 10 In an important case series from Varga et al., 11 postmortem histology from three patients affected by late‐stage COVID‐19, revealed viral inclusions in endothelial apoptotic cells and microvascular lymphocytic endotheliitis, with infiltration of inflammatory cells around the vessels and endothelial cells (ECs), as well as evidence of endothelial apoptotic cell death in the lung, kidney, small bowel and heart. Additionally, autopsy findings of 27 patients in another series confirmed the detection of the SARS‐CoV‐2 in multiple organs, including the respiratory tract, pharynx, heart, liver, brain, and kidneys. 12 Immunofluorescence of kidney specimens from six of the 27 patients showed the presence of SARS‐CoV‐2 protein in all renal compartments, and in three of the patients preferentially in the endothelium of the glomerulus. Similar microscopic findings were also noted in lung specimens from seven patients with COVID‐19, which displayed small vessel endotheliitis, microvascular thrombosis and angiogenesis, along with the presence of SARS‐CoV‐2 in pulmonary ECs, an observation strongly supporting the vascular tropism of the virus. 13 Lastly, Stahl et al. 14 have identified in the plasma and serum of 19 critically ill patients with COVID‐19 evidence of disruption of the endothelial glycocalyx, reflected by increased levels of the Tie‐2 receptor and syndecan‐1 (SDC‐1), a heparan sulphate (HS) proteoglycan. This particular observation is of interest as the endothelial glycocalyx covers the luminal surface of ECs, and its integrity is vital for the maintenance of vascular homeostasis.

Such findings suggest that virus‐mediated apoptosis may promote endothelial barrier disruption with interstitial oedema and increased recruitment of circulating activated immune cells, thus causing widespread endothelial dysfunction, as well as activation of platelets and the coagulation cascade leading to venous and arterial thrombosis. 15 Altered pro‐inflammatory and pro‐thrombotic status is confirmed by the presence of elevated inflammation‐related indices (e.g. C‐reactive protein and serum ferritin), humoral biomarkers [interleukin (IL)‐2, IL‐6, IL‐7, granulocyte‐colony stimulating factor (G‐CSF), tumour necrosis factor‐alpha (TNF‐α)], and indicators of an increased pro‐coagulant‐fibrinolytic state [e.g. von Willebrand factor (VWF), D‐dimer, fibrinogen]. Further, factor VIII (FVIII), a potent and key factor in the coagulation process, is greatly increased in ICU patients with COVID‐19. 16

In this setting, it has been proposed that the systemic hyperinflammation observed in severe COVID‐19 is comparable to a cytokine release syndrome (CRS), or cytokine storm. IL‐6 has a central role in the generation of the cytokine storm, and is commonly elevated in the serum of severely ill patients with COVID‐19. 17 High levels of IL‐6 activate ECs, thus resulting in vascular leakage, further cytokine secretion and activation of the complement and coagulation cascades. 18 Interestingly, a population of IL‐6 producing monocytes was found to be expanded in the peripheral blood of ICU patients 19 and an aberrant macrophage response exhibiting increased levels of pro‐inflammatory cytokines has been detected in bronchoalveolar fluid, especially in severely ill patients. 20 Although the exact driver of monocyte activation remains unclear, such cells are attracted to the endothelium, where the release of highly noxious molecules, such as reactive oxygen species (ROS), contributes to endothelial dysfunction and promotes hyperinflammation. 21 Further, activated monocytes enhance tissue factor expression and form aggregates with platelets through P‐selectin interaction and hence augmenting the pro‐coagulant response. 22 Indeed, significantly increased levels of VWF and FVIII and thrombomodulin, 16 aberrant coagulation, thrombosis and microangiopathy are very common in critically ill patients with COVID‐19, resulting in a disseminated intravascular coagulation (DIC)‐like syndrome characterised by massive fibrin formation and organ dysfunction. 23 Likewise, adaptive immunity actively participates in the establishment of the inflammatory response; specifically, activated and proliferating CD8+ T cells are prevalent in mild COVID‐19, whereas critically ill patients display higher levels of hyperactive IL‐6‐producing CD4+ T cells, which may contribute to disease severity, even after viral clearance. 17 Interestingly, T cells show phenotypical signs of an exhausted, functionally unresponsive state, thus allowing viral escape from immune surveillance. 22 Once initiated, the endotheliitis and resultant cytokine storm become self‐sustaining, leading to widespread organ damage. Some patients may also display features of haemophagocytic lymphohistiocytosis, such as cytopenias, hyperferritinaemia and rapid onset of MOF.

Overall, once hyperinflammation and CRS develop, rates of mortality significantly increase. 24 25 26 As direct viral activation of the vascular endothelium has an important role in initiating and maintaining the hyperinflammatory response, attempting to blunt such a response with endothelial‐protective agents is a very rational strategy. Controlled clinical trials focussing on the use of anti‐cytokine antibodies, including tocilizumab (IL‐6 inhibitor), have failed to show significant activity in this stage of the disease. 27 However, increasing evidence suggests that the altered homeostasis of the endothelium may be a key initiating event in the pathogenesis of the disease, therefore representing a potentially more promising target. 28Go to:

Endothelial cell‐related disorders in haematology: post‐bone marrow transplantation syndromes and sickle cell disease and the overlap with the pathobiology of COVID‐19

Clinically and histopathologically, COVID‐19‐associated endotheliitis resembles a spectrum of post‐bone marrow and stem cell transplantation (BMT) syndromes characterised by disruption of endothelial homeostasis and consequently dysregulation of coagulation, vascular tone, endothelial permeability and vascular inflammation. 29 These disorders include hepatic veno‐occlusive disease (VOD)/sinusoidal obstruction syndrome (SOS), idiopathic pneumonia syndrome (IPS), transplant‐associated thrombotic microangiopathy and graft‐versus‐host disease (GvHD).

Hepatic VOD/SOS develops as a result of endothelial damage to hepatic sinusoids and subsequent hepatocyte necrosis 30 . Damage to the ECs leads to a hypercoagulable state, production of inflammatory mediators, and the upregulation as well as release of heparanase. 31 Heparanase degrades the heparan sulphate scaffold of the subendothelial basement membrane, consequently allowing the extravasation of blood‐borne cells, including activated T lymphocytes, neutrophils and macrophages. 32 This cascade of events leads to postsinusoidal hypertension, hyperinflammation and ultimately MOF. Severe VOD/SOS associated with MOF without effective therapy is fatal in >80% of cases. 33 Interestingly, the histopathological examination of lung lesions in VOD/SOS shows early alveolar epithelial and lung endothelial injury, resulting in accumulation of protein‐ and fibrin‐rich inflammatory oedematous fluid in the alveolar space and progression to interstitial fibrosis, 34 35 as is also seen in fatal COVID‐19 cases.

Similarly, IPS, a widespread alveolar injury in the absence of identifiable infectious or non‐infectious causes, is characterised by histological evidence of EC injury with fibrin accumulation, luminal thrombosis and fibrotic processes. Adhesion molecules, such as intercellular adhesion molecule 1 (ICAM‐1) and/or vascular cell adhesion molecule 1 (VCAM‐1), are commonly upregulated, thus reflecting profound endothelial activation. 36 It has been suggested that TNF‐α directly causes endothelial injury, and increased levels of angiopoietin‐2 (Ang‐2), have been recently reported in cases of acute exacerbations of IPS, 37 similar to that seen in severely ill patients with COVID‐19. 38

Likewise, multifactorial endothelial damage has been also implicated in the development of transplant‐associated thrombotic microangiopathy, where micro‐vessel intimal swelling and necrosis lead to the formation of luminal microthrombi and subsequent microangiopathic haemolytic anaemia. Plasma levels of markers of EC injury and inflammation, such as thrombomodulin, plasminogen activator inhibitor‐1 (PAI‐1), ICAM‐1, VCAM‐1, IL‐1, TNF‐α, interferon gamma and IL‐8 are commonly elevated. 39 40 Endothelial dysfunction predominantly affects the kidneys and the brain, but may become widespread and progress to MOF, which in turn is associated with high mortality.

Lastly, acute GvHD (aGvHD) develops as a consequence of the activation of the immune system. Antigen‐presenting cells become activated by endothelial and tissue damage derived from direct toxicity of the conditioning regimen, thus initiating an alloreactive T‐cell response directed against recipient tissues. 41 As a result, SDC‐1 is commonly elevated in the serum of patients with GvHD and correlates with disease severity. 42 In addition to cell‐mediated cytotoxic damage, the cytokine storm generated in response to T‐cell activation and proliferation causes targeted organ damage involving mainly the skin, liver and gut. 43 It has recently been suggested that endothelial vulnerability and pro‐thrombotic shift precedes clinically evident aGvHD and that angiogenesis driven by early endothelial activation is an initiating event. 44 Indeed, increased plasma levels of VWF, 45 Ang‐2 46 and TNF receptor 1 47 have been detected in patients prior to development of aGvHD, correlating with response to therapy.

Similarly, markers of endothelial dysfunction and inflammatory activation have been detected also in the serum of patients with sickle cell disease (SCD), especially during vaso‐occlusive episodes. SCD is characterised by a chronic course of relapsing‐remitting episodes of ischaemia and then reperfusion. The polymerisation of defective haemoglobin S upon deoxygenation initiates many pathological processes, such as complement activation, generation of ROS and pro‐thrombotic molecules, secretion of numerous pro‐inflammatory cytokines and chemokines and ultimately leucocyte recruitment. 48 Oxidative stress and endothelial dysregulation plays a key role in vaso‐occlusion; ECs activated by substances released by the haemolytic process and by red blood cell adhesion initiate production and release of soluble mediators such as IL‐1β, IL‐8, IL‐6, IL‐1α and PAI‐1, 49 50 and increase the expression of adhesion molecules such as VCAM‐1, ICAM‐1, E‐selectin and P‐selectin, 51 52 reflecting a pro‐inflammatory and pro‐thrombotic shift. Vaso‐occlusive phenomena commonly affect the lung vasculature, provoking acute chest syndrome (ACS), a spectrum of diseases ranging from mild pneumonia to ARDS and MOF, which is the leading cause of morbidity and mortality in SCD. 53 Lung specimens from ACS cases showed micro‐thrombotic occlusion, endothelial VWF deposition and arterial vessel re‐modelling with initial fibrotic processes, 54 fascinatingly all comparable to the histopathological findings in COVID‐19. 55 Importantly, heme‐mediated endothelial damage to alveolar cells is regulated by the p38 mitogen‐activated protein kinase (MAPK) pathway, which plays a crucial role in the biosynthesis of pro‐inflammatory cytokines and collagen production. 56 This key pathway is also upregulated in COVID‐19 as a result of decreased ACE2 tissue functionality consequent to viral binding, and may consequently promote endotheliitis, hypercoagulation and end‐stage fibrosis. 57 58

In summary, post‐BMT syndromes, vaso‐occlusive organ dysfunction in SCD and COVID‐19‐associated endotheliitis share common pathological mechanisms including: i) dysregulation of the homeostasis of the endothelial milieu toward a pro‐inflammatory and pro‐thrombotic phenotype with thrombotic microangiopathy; ii) hyperproduction of inflammatory cytokines such as IL‐6, IL‐8 and TNF‐α; 59 60 61 62 and iii) small vessel endotheliitis and endothelial barrier dysfunction, leading to oedema of the microvascular bed, protein and fibrin accumulation and subsequent fibrotic shift. 34 36 All these conditions if untreated irremediably lead to MOF and display similar microscopic and macroscopic features in target organs upon pathological examination. At the molecular level, the p38 MAPK pathway may also be critical in promoting vasoconstrictive and inflammatory phenomena; its activation is described in SCD, COVID‐19 and also as a result of conditioning regimen‐induced endothelial damage in BMT. 63 Together, these findings support the notion that the pleiotropic character of the endothelium as a key regulator of the internal homeostasis, vascular tone, blood coagulation and the inflammatory process and therefore of so called ‘immune‐thrombosis’ events, make it an intriguing therapeutic target for post‐BMT disorders, SCD, and COVID‐19.Go to:

Agents targeting EC‐related disorders

Heparins

Classically, heparins have been the most widely used drugs for the treatment and prevention of endothelial cell disorders. Several animal studies and clinical trials have suggested that, in addition to its well‐known anticoagulant effects, heparin also possesses anti‐inflammatory properties, mainly mediated by inhibition of IL‐6 release and its activity, 64 a phenomena also demonstrated in patients with COVID‐19 treated with low‐molecular‐weight heparin. 65 Further, heparin is structurally related to HS, 66 a negatively charged glycosaminoglycan as described earlier, which serves as binding sites for growth factors, cytokines, selectins, extracellular‐matrix molecules, and a large number of human viruses, 67 including the SARS‐CoV‐2 virus. 68 69 Indeed, Clausen et al. 70 have recently demonstrated that the SARS‐CoV‐2 spike protein must bind both the ACE2 receptor and HS to enter human cells. The structural analogies between heparin and HS may result in competitive inhibition, where heparin and related compounds compete with the cell surface HS for viral binding to target cells, 68 69 thus potentially blocking or at least attenuating viral entry. The beneficial effects of heparin‐based therapies are also linked to their inhibition of circulating heparanase enzymatic activity. 32 Heparanase, an endo‐β‐glucuronidase, physiologically cleaves HS chains located in extracellular matrices and on cell surfaces. 32 It is often overexpressed during viral infections and act as a regulator of virus release after replication has occurred, promoting its dissemination. 71 72 73 74 Additionally, it may be upregulated by pro‐inflammatory molecules such as IL‐1 and TNF‐α. Once activated, heparanase stimulates the expression and release of pro‐inflammatory cytokines, including TNF‐α, IL‐1 and IL‐6. 75 The enzyme has been implicated in cancer progression, inflammation, 76 VOD/SOS development 77 and other vascular pathologies. 71

Currently, numerous clinical trials are underway to investigate the therapeutic potential of intravenous and subcutaneous heparin, as well as the appropriate dose regimen in COVID‐19. Further, nebulised heparin delivered directly to the airways may be effective in preventing infection and mitigating lung disease (clinicaltrials.gov; NCT04545541NCT04511923). Notwithstanding their anticoagulant, anti‐inflammatory and anti‐viral properties, the use of heparins is associated with a substantially increased risk of systemic bleeding, and other challenging ‘off‐target’ effects, making its use potentially part of the standard of care, but not without qualification, as well as highlighting the need for combination approaches.

Defibrotide

The use of defibrotide (DF), which has both comparable but distinct properties from heparins and negligible haemorrhagic risk 78 may therefore be warranted, especially given the established propensity for the development of DIC later in the COVID‐19 clinical course. DF is a naturally derived, complex mixture of poly‐deoxyribonuleotides extracted originally from bovine lung and now exclusively from porcine gut mucosa. 79 80 Since its original isolation >30 years ago, DF has demonstrated locally acting pro‐fibrinolytic, 81 82 83 84 anti‐thrombotic, 85 86 anti‐ischaemic and anti‐inflammatory activities, which exert protective effects on small vessel endothelia. It is currently approved for the treatment of paediatric and adult hepatic VOD/SOS with MOF. 87 88 89 In this setting, DF has demonstrated efficacy and safety in critically ill patients with MOF, as well as a significant reduction in PAI‐1 and other markers of endothelial stress in patients with VOD/SOS and MOF successfully treated with DF. 89 90 91 Furthermore, in a pivotal Phase III trial, DF prophylaxis reduced the incidence and severity of VOD/SOS in high‐risk children undergoing BMT. 92 In a more recent study, Palomo et al. 93 demonstrated that DF directly interacts with the cell membrane and becomes internalised by ECs, thus providing physical evidence of its endothelial‐protective properties. In particular, DF appears to decrease levels of pro‐inflammatory proteins, such as TNF‐α, 94 IL‐6, vascular endothelial growth factor (VEGF) 95 and to downregulate major histocompatibility complex (MHC) Class I and Class II molecules, 96 97 therefore attenuating both the inflammatory and immune responses. Furthermore, it appears to decrease interaction between leucocytes and ECs by downregulating P‐selectin, 98 ICAM‐1 95 and VCAM‐1. 99 Lastly, DF displays potent adenosine agonism. 100 Such activity may be clinically relevant, not least based on substantial improvement observed in an animal model of acute lung injury upon treatment with adenosine receptor agonists. 101

Based on such properties, the use of DF can be reasonably extended to other post‐BMT syndromes and other microangiopathies involving CRS complicating a variety of disease states and treatment modalities, such as chimeric antigen receptor (CAR) T‐cell therapy. 102 Indeed, paediatric and adult patients receiving DF as VOD/SOS prophylaxis also exhibited a reduced incidence of aGvHD, 92 103 a finding that is strongly supported by a preclinical model of aGvHD. 99 Additionally, a retrospective survey from paediatric patients treated with DF for transplant‐associated thrombotic microangiopathy showed resolution of clinical disease in 77% of patients. 104 Currently, Phase II studies investigating the use of DF for prevention of transplant‐associated thrombotic microangiopathy and VOD, and in the same context the treatment of ACS are ongoing (clinicaltrials.gov; NCT03384693NCT03805581NCT02675959). Notably, DF suppresses the expression of heparanase transcripts, cell surface expression and enzymatic activity, 95 suggesting that DF may have anti‐viral properties, although this remains to be confirmed. 71 72 73 Heparanase is putatively upregulated by the cytokine storm of advanced COVID‐19 and may contribute to further inflammation, oedema of the microvascular bed and coagulopathy. 28 75 105 106 DF is a potent inhibitor of heparanase in terms of both cell surface and gene expression, and therefore is especially attractive. Furthermore, the therapeutic use of DF in a murine model of IPS significantly improved survival compared to untreated controls by reducing, among other biomarkers, the levels of Ang‐2, 107 which is known to correlate with ARDS and is markedly elevated in critically ill patients with COVID‐19. 38

In addition, ICU‐admitted patients with COVID‐19 may display increased platelet activation and subsequent formation of platelet‐monocyte aggregates upon interaction with P‐selectin, thus stimulating monocyte‐induced inflammation and thrombosis. 22 By reducing P‐selectin and other adhesion molecules expression, DF may inhibit monocyte‐derived inflammatory and pro‐coagulant signals. Lastly and most importantly, DF has also been shown to decrease the activity of p38 MAPK and its pathway, 93 the importance of which is increasingly recognised in the pathogenesis of the COVID‐19 hyperinflammation syndrome and this may be a key therapeutic target in this process. 58 108

In summary, the multitargeted endothelial‐based therapeutic properties of DF and its relative safety, as well as its regulatory approval, make it an ideal potential therapeutic candidate for the treatment of COVID‐19 vascular complications. 28 In contrast to heparin, DF also exhibits broader anti‐cytokine, anti‐inflammatory and endothelial‐stabilising properties. Importantly, by acting on the heparanase‐HS axis, 74 102 DF may limit viral infectivity given its capacity to i) compete with HS and thereby possibly inhibit virus–cell adhesion and entry, ii) inhibit heparanase enzymatic activity and thereby attenuate virus detachment/release and spread 74 and iii) inhibit heparanase‐mediated activation of immune cells and thereby upregulation of pro‐inflammatory cytokines and the associated self‐sustaining systemic inflammatory host response (Fig 1). Actively accruing, international Phase II clinical trials are now underway and should shed critical light on DF’s therapeutic potential in patients with COVID‐19 (examples include clinicaltrials.gov; NCT04348383NCT04335201). Strikingly, two critically ill paediatric patients treated with DF for a SARS‐CoV‐2‐associated multisystem inflammatory syndrome experienced complete resolution and no attributable toxicity, with correlative studies supporting the mechanistic effects described above, as well as favourable effects seen on complement activation. 109 Similarly, preliminary results from the current studies as part of the international DEFACOVID (Defibrotide as Prevention and Treatment of Respiratory Distress and Cytokine Release Syndrome of COVID‐19) study group support both safety and promising potential efficacy to date.Fig 1

Potential mechanisms of action of defibrotide in the treatment of COVID‐19. Left, defibrotide limits viral attachment by interfering with Syndecan‐1, the primary cell surface heparan sulfate on ECs, and reduces viral dissemination, by inhibiting HPSE‐mediated viral release. Right, effects of defibrotide on endothelial‐mediated pathological processes. Viral infection of ECs promotes apoptosis with breakdown of endothelial barrier and exposure of the subendothelium, with subsequent platelet activation and thrombotic phenomena. Defibrotide inhibits platelet activation and leukocyte recruitment and blocks the generation of the cytokine storm; specifically, HPSE‐mediated activation of immune cells is suppressed, thus limiting the development of cytokine release syndrome. Sars‐Cov‐2, severe acute respiratory syndrome coronavirus‐2; ACE2, angiotensin‐converting enzyme 2; Ang‐2, angiopoietin‐2; GI, gastrointestinal; IL, interleukin; NFKB, nuclear factor kappa‐light chain‐enhancer of activated B cells; TNF‐α, tumor necrosis factor‐alpha; VWF, von Willebrand Factor.

Other heparanase inhibitors

Given the heparanase‐inhibiting activity of heparin, effort has been directed towards modifications of its structure to endow candidate molecules with potentiated anti‐heparanase activity while limiting anticoagulant effects. Specifically, N‐acetylated and glycol‐split heparins are promising agents presenting such characteristics. Indeed, administration of N‐acetylheparin (NAH) in murine models of sepsis ameliorated lung and intestinal injury and subsequent oedema by reducing tissue neutrophilic infiltration and suppressing IL‐6, IL‐1β and TNF‐α production. 110 111 Furthermore, roneparstat, the most developed glycol‐split NAH, restored pathological renal cellular damage caused by ischaemia‐reperfusion by reducing release of pro‐inflammatory cytokines and reverted established fibrotic processes, thus restoring normal tissue histology in preclinical models. 112 This aspect is especially relevant, considering the extensive formation of fibrosis and irreversible end‐organ damage in post‐BMT syndromes, SCD and advanced COVID‐19.

Additionally, much interest has been directed towards the novel heparanase‐inhibiting agent pixatimod, a modified oligosaccharide glycoside with heparan sulphate‐mimetic properties. Pixatimod is a potent inhibitor of Type 1 T‐helper cells (Th1)/Th17 effector functions, 113 IL‐6 expression, 114 M2 macrophage activation, 115 angiogenesis and tumour progression in vivo. Furthermore, it exhibits mild anticoagulant activity and despite transient infusion reactions is otherwise generally well tolerated. Guimond et al. 116 have recently demonstrated that pixatimod interacts with the SARS‐CoV‐2 spike protein binding site, and this is coherent with its heparan sulphate‐mimetic activity. Moreover, pixatimod was found to markedly inhibit SARS‐CoV‐2 infectivity, 116 supporting its clinical application as a novel therapeutic intervention for prophylaxis and treatment of COVID‐19. Taken together, heparanase emerges as a host‐encoded virulence factor that once activated enhances viral spread and triggers downstream inflammatory cascades. These preliminary data indicate that heparanase inhibitors currently under development are possible candidates for multisystem inflammatory conditions, such as COVID‐19, sepsis, thrombotic microangiopathies and cancer, but as of now studies remain preclinical with clinical application pending.

Conclusions

In conclusion, increasing evidence suggests that the SARS‐CoV‐2 directly targets ECs, promoting the release of pro‐inflammatory and pro‐thrombotic molecules. Endothelial dysfunction appears to be a crucial initiating step in the pathogenesis of the disease and its ensuing morbidity and mortality. Endotheliitis with the hyperproduction of cytokines leading to CRS, hypercoagulability and thrombotic microangiopathy are hallmarks shared by COVID‐19, VOD/SOS and other endothelial injury syndromes, underpinned by inflammation and including the vaso‐occlusive crises of SCD, so providing a common pathobiology across these respective syndromes. Most importantly, endothelial‐protective agents, such as DF, represent a promising and rational therapeutic strategy in COVID‐19, with DF currently under investigation in a variety of settings and combinations. As a unifying concept, heparanase inhibition, with the modulation of related pathways and other effects on endothelial stress responses may thus be crucial in mediating anti‐viral and anti‐inflammatory activity. In particular, as this relates to endotheliitis, it may directly abrogate CRS and its sequelae, which in turn may lead to improved patient outcome.

Author Contributions

Eleonora Calabretta, Jose M. Moraleda, Israel Vlodavsky, Ruben Jara, Carmelo Carlo‐Stella and Paul Richardson drafted the manuscript; all authors participated in the critical revision and approval of the final report.Go to:

Conflict of interest

Jose M. Moraleda declares Advisory Board fees from Jazz Pharmaceuticals; Antonio Pagliuca has received Advisory Board and Speaker fees from Jazz Pharmaceuticals; Rebecca M. Baron is on a Merck Advisory Board and a Consultant for Genentech. Robert Soiffer serves on the Board of Directors for Kiadis and Be The Match/National Marrow Donor Program; provided consulting for Gilead, Rheos Therapeutics, Cugene, Precision Bioscience, Mana Therapeutics, VOR Biopharma, and Novartis; and Data Safety Monitoring Board for Juno/Celgene; Paul Richardson is an Advisory Committee Member for Jazz Pharmaceuticals; Carmelo Carlo‐Stella is a Consultant/Advisory Board Member for Genente Science srl, ADC Therapeutics, Novartis, Roche, Karyopharm, Sanofi, Boehringer Igelheim and Servier. The remaining authors declare nothing to disclose.

Acknowledgments

This work was supported in part by a grant from the Italian Association for Cancer Research (AIRC, grant #20575 to CC‐S).Go to:

Contributor Information

Carmelo Carlo‐Stella, Email: ue.deminuh@alletsolrac.olemrac.

Paul Richardson, Email: ude.dravrah.icfd@nosdrahcir_luap.Go to:

References

1. Huang C, Wang Y, Li X, Ren L, Zhao J, Hu Y, et al. Clinical features of patients infected with 2019 novel coronavirus in Wuhan, China. Lancet. 2020;395:497–506. [PMC free article] [PubMed] [Google Scholar]

2. World Health Orgnization (WHO) . Coronavirus disease (COVID‐19) pandemic. Available at: https://www.who.int. Accessed January 2021

3. Wang D, Hu B, Hu C, Zhu F, Liu X, Zhang J, et al. Clinical characteristics of 138 hospitalized patients with 2019 novel coronavirus‐infected pneumonia in Wuhan, China. JAMA. 2020;323:1061–9. [PMC free article] [PubMed] [Google Scholar]

4. Onder G, Rezza G, Brusaferro S. Case‐fatality rate and characteristics of patients dying in relation to COVID‐19 in Italy. JAMA. 2020;323:1775–6. [PubMed] [Google Scholar]

5. Grasselli G, Zangrillo A, Zanella A, Antonelli M, Cabrini L, Castelli A, et al. Baseline characteristics and outcomes of 1591 patients infected with SARS‐CoV‐2 admitted to ICUs of the Lombardy Region, Italy. JAMA. 2020;323:1574–81. [PMC free article] [PubMed] [Google Scholar]

6. Horby P, Lim WS, Emberson JR, Mafham M, Bell JL, Linsell L, et al. Dexamethasone in Hospitalized Patients with Covid‐19 – preliminary report. N Engl J Med. 2020. [Online ahead of print]. 10.1056/NEJMoa2021436. [PMC free article] [PubMed] [CrossRef] [Google Scholar]

7. Beigel JH, Tomashek KM, Dodd LE, Mehta AK, Zingman BS, Kalil AC, et al. Remdesivir for the treatment of Covid‐19 – final report. N Engl J Med. 2020;383:1813–26. [PMC free article] [PubMed] [Google Scholar]

8. Siddiqi HK, Mehra MR. COVID‐19 illness in native and immunosuppressed states: a clinical‐therapeutic staging proposal. J Heart Lung Transplant. 2020;39:405–7. [PMC free article] [PubMed] [Google Scholar]

9. Wan Y, Shang J, Graham R, Baric RS, Li F. Receptor Recognition by the Novel Coronavirus from Wuhan: an Analysis Based on Decade‐Long Structural Studies of SARS Coronavirus. J Virol. 2020. [Online ahead of print]. DOI: 10.1128/JVI.00127‐20. [PMC free article] [PubMed] [Google Scholar]

10. Ferrario CM, Trask AJ, Jessup JA. Advances in biochemical and functional roles of angiotensin‐converting enzyme 2 and angiotensin‐(1–7) in regulation of cardiovascular function. Am J Physiol Heart Circ Physiol. 2005;289:H2281–90. [PMC free article] [PubMed] [Google Scholar]

11. Varga Z, Flammer AJ, Steiger P, Haberecker M, Andermatt R, Zinkernagel AS, et al. Endothelial cell infection and endotheliitis in COVID‐19. Lancet. 2020;395:1417–8. [PMC free article] [PubMed] [Google Scholar]

12. Puelles VG, Lütgehetmann M, Lindenmeyer MT, Sperhake JP, Wong MN, Allweiss L, et al. Multiorgan and renal tropism of SARS‐CoV‐2. N Engl J Med. 2020;383:590–2. [PMC free article] [PubMed] [Google Scholar]

13. Ackermann M, Verleden SE, Kuehnel M, Haverich A, Welte T, Laenger F, et al. Pulmonary Vascular Endothelialitis, Thrombosis, and Angiogenesis in Covid‐19. N Engl J Med. 2020;383:120–8. [PMC free article] [PubMed] [Google Scholar]

14. Stahl K, Gronski PA, Kiyan Y, Seeliger B, Bertram A, Pape T, et al. Injury to the Endothelial Glycocalyx in Critically Ill COVID‐19 Patients. Am J Respir Crit Care Med. 2020. [PMC free article] [PubMed] [Google Scholar]

15. Azouz E, Yang S, Monnier‐Cholley L, Arrivé L. Systemic arterial thrombosis and acute mesenteric ischemia in a patient with COVID‐19. Intensive Care Med. 2020;46:1464–5. [PMC free article] [PubMed] [Google Scholar]

16. Goshua G, Pine AB, Meizlish ML, Chang CH, Zhang H, Bahel P, et al. Endotheliopathy in COVID‐19‐associated coagulopathy: evidence from a single‐centre, cross‐sectional study. Lancet Haematol. 2020;7:e575–82. [PMC free article] [PubMed] [Google Scholar]

17. Wu C, Chen X, Cai Y, Xia J, Zhou X, Xu S, et al. Risk factors associated with acute respiratory distress syndrome and death in patients with coronavirus disease 2019 pneumonia in Wuhan, China. JAMA Intern Med. 2020;180:934–43. [PMC free article] [PubMed] [Google Scholar]

18. Moore JB, June CH. Cytokine release syndrome in severe COVID‐19. Science. 2020;368:473–4. [PubMed] [Google Scholar]

19. Zhou Y, Fu B, Zheng X, Wang D, Zhao C, Qi Y, et al. Pathogenic T‐cells and inflammatory monocytes incite inflammatory storms in severe COVID‐19 patients. Nati Sci Rev. 2020;7:998–1002. [Google Scholar]

20. Liao M, Liu Y, Yuan J, Wen Y, Xu G, Zhao J, et al. Single‐cell landscape of bronchoalveolar immune cells in patients with COVID‐19. Nat Med. 2020;26:842–4. [PubMed] [Google Scholar]

21. Merad M, Martin JC. Pathological inflammation in patients with COVID‐19: a key role for monocytes and macrophages. Nat Rev Immunol. 2020;20:355–62. [PMC free article] [PubMed] [Google Scholar]

22. Hottz ED, Azevedo‐Quintanilha IG, Palhinha L, Teixeira L, Barreto EA, Pão CRR, et al. Platelet activation and platelet‐monocyte aggregate formation trigger tissue factor expression in patients with severe COVID‐19. Blood. 2020;136:1330–41. [PMC free article] [PubMed] [Google Scholar]

23. Tang N, Li D, Wang X, Sun Z. Abnormal coagulation parameters are associated with poor prognosis in patients with novel coronavirus pneumonia. J Thromb Haemost. 2020;18:844–7. [PMC free article] [PubMed] [Google Scholar]

24. Ruan Q, Yang K, Wang W, Jiang L, Song J. Clinical predictors of mortality due to COVID‐19 based on an analysis of data of 150 patients from Wuhan, China. Intensive Care Med. 2020;46:846–8. [PMC free article] [PubMed] [Google Scholar]

25. Chen G, Wu D, Guo W, Cao Y, Huang D, Wang H, et al. Clinical and immunological features of severe and moderate coronavirus disease 2019. J Clin Investig. 2020;130:2620–9. [PMC free article] [PubMed] [Google Scholar]

26. Price CC, Altice FL, Shyr Y, Koff A, Pischel L, Goshua G, et al. Tocilizumab treatment for cytokine release syndrome in hospitalized COVID‐19 patients: survival and clinical outcomes. Chest. 2020;158:1397–1408. [PMC free article] [PubMed] [Google Scholar]

27. Rosas I, Bräu N, Waters M, Go RC, Hunter BD, Bhagani S, et al. Tocilizumab in hospitalized patients with COVID‐19 pneumonia. medRxiv. 2020;2020.08.27.20183442. [Google Scholar]

28. Teuwen LA, Geldhof V, Pasut A, Carmeliet P. COVID‐19: the vasculature unleashed. Nat Rev Immunol. 2020;20:389–91. [PMC free article] [PubMed] [Google Scholar]

29. Hildebrandt GC, Chao N. Endothelial cell function and endothelial‐related disorders following haematopoietic cell transplantation. Br J Haematol. 2020;190:508–19. [PMC free article] [PubMed] [Google Scholar]

30. Valla DC, Cazals‐Hatem D. Sinusoidal obstruction syndrome. Clin Res Hepatol Gastroenterol. 2016;40:378–85. [PubMed] [Google Scholar]

31. Richardson PG, Corbacioglu S, Ho VT, Kernan NA, Lehmann L, Maguire C, et al. Drug safety evaluation of defibrotide. Expert Opin Drug Saf. 2013;12:123–36. [PubMed] [Google Scholar]

32. Vlodavsky I, Ilan N, Sanderson RD. Forty years of basic and translational heparanase research. Adv Exp Med Biol. 2020;1221:3–59. [PMC free article] [PubMed] [Google Scholar]

33. Coppell JA, Richardson PG, Soiffer R, Martin PL, Kernan NA, Chen A, et al. Hepatic veno‐occlusive disease following stem cell transplantation: incidence, clinical course, and outcome. Biol Blood Marrow Transplant. 2010;16:157–68. [PMC free article] [PubMed] [Google Scholar]

34. Bunte MC, Patnaik MM, Pritzker MR, Burns LJ. Pulmonary veno‐occlusive disease following hematopoietic stem cell transplantation: a rare model of endothelial dysfunction. Bone Marrow Transplant. 2008;41:677–86. [PubMed] [Google Scholar]

35. Mandel J, Mark EJ, Hales CA. Pulmonary veno‐occlusive disease. Am J Respir Crit Care Med. 2000;162:1964–73. [PubMed] [Google Scholar]

36. Altmann T, Slack J, Slatter MA, O’Brien C, Cant A, Thomas M, et al. Endothelial cell damage in idiopathic pneumonia syndrome. Bone Marrow Transplant. 2018;53:515–8. [PubMed] [Google Scholar]

37. Ando M, Miyazaki E, Abe T, Ehara C, Goto A, Masuda T, et al. Angiopoietin‐2 expression in patients with an acute exacerbation of idiopathic interstitial pneumonias. Respir Med. 2016;117:27–32. [PubMed] [Google Scholar]

38. Smadja DM, Guerin CL, Chocron R, Yatim N, Boussier J, Gendron N, et al. Angiopoietin‐2 as a marker of endothelial activation is a good predictor factor for intensive care unit admission of COVID‐19 patients. Angiogenesis. 2020;23:611–20. [PMC free article] [PubMed] [Google Scholar]

39. Batts ED, Lazarus HM. Diagnosis and treatment of transplantation‐associated thrombotic microangiopathy: real progress or are we still waiting? Bone Marrow Transplant. 2007;40:709–19. [PubMed] [Google Scholar]

40. Seaby EG, Gilbert RD. Thrombotic microangiopathy following haematopoietic stem cell transplant. Pediatr Nephrol. 2018;33(9):1489–500. [PMC free article] [PubMed] [Google Scholar]

41. Ghimire S, Weber D, Mavin E, Wang XN, Dickinson AM, Holler E. Pathophysiology of GvHD and Other HSCT‐related major complications. Front Immunol. 2017;8:79. [PMC free article] [PubMed] [Google Scholar]

42. Seidel C, Ringdén O, Remberger M. Increased levels of syndecan‐1 in serum during acute graft‐versus‐host disease. Transplantation. 2003;76:423–6. [PubMed] [Google Scholar]

43. Holtan SG, Pasquini M, Weisdorf DJ. Acute graft‐versus‐host disease: a bench‐to‐bedside update. Blood. 2014;124:363–73. [PMC free article] [PubMed] [Google Scholar]

44. Riesner K, Shi Y, Jacobi A, Kräter M, Kalupa M, McGearey A, et al. Initiation of acute graft‐versus‐host disease by angiogenesis. Blood. 2017;129:2021–32. [PubMed] [Google Scholar]

45. Mir E, Palomo M, Rovira M, Pereira A, Escolar G, Penack O, et al. Endothelial damage is aggravated in acute GvHD and could predict its development. Bone Marrow Transplant. 2017;52:1317–25. [PubMed] [Google Scholar]

46. Dietrich S, Falk CS, Benner A, Karamustafa S, Hahn E, Andrulis M, et al. Endothelial vulnerability and endothelial damage are associated with risk of graft‐versus‐host disease and response to steroid treatment. Biol Blood Marrow Transplant. 2013;19:22–7. [PubMed] [Google Scholar]

47. Choi SW, Kitko CL, Braun T, Paczesny S, Yanik G, Mineishi S, et al. Change in plasma tumor necrosis factor receptor 1 levels in the first week after myeloablative allogeneic transplantation correlates with severity and incidence of GVHD and survival. Blood. 2008;112:1539–42. [PMC free article] [PubMed] [Google Scholar]

48. Conran N, Belcher JD. Inflammation in sickle cell disease. Clin Hemorheol Microcirc. 2018;68:263–99. [PMC free article] [PubMed] [Google Scholar]

49. Pathare A, Al Kindi S, Alnaqdy AA, Daar S, Knox‐Macaulay H, Dennison D. Cytokine profile of sickle cell disease in Oman. Am J Hematol. 2004;77:323–8. [PubMed] [Google Scholar]

50. Sakamoto TM, Lanaro C, Ozelo MC, Garrido VT, Olalla‐Saad ST, Conran N, et al. Increased adhesive and inflammatory properties in blood outgrowth endothelial cells from sickle cell anemia patients. Microvasc Res. 2013;90:173–9. [PubMed] [Google Scholar]

51. Duits AJ, Pieters RC, Saleh AW, van Rosmalen E, Katerberg H, Berend K, et al. Enhanced levels of soluble VCAM‐1 in sickle cell patients and their specific increment during vasoocclusive crisis. Clin Immunol Immunopathol. 1996;81:96–8. [PubMed] [Google Scholar]

52. Embury SH, Matsui NM, Ramanujam S, Mayadas TN, Noguchi CT, Diwan BA, et al. The contribution of endothelial cell P‐selectin to the microvascular flow of mouse sickle erythrocytes in vivo. Blood. 2004;104:3378–85. [PubMed] [Google Scholar]

53. Platt OS, Brambilla DJ, Rosse WF, Milner PF, Castro O, Steinberg MH, et al. Mortality in sickle cell disease. Life expectancy and risk factors for early death. N Engl J Med. 1994;330:1639–44. [PubMed] [Google Scholar]

54. Anea CB, Lyon M, Lee IA, Gonzales JN, Adeyemi A, Falls G, et al. Pulmonary platelet thrombi and vascular pathology in acute chest syndrome in patients with sickle cell disease. Am J Hematol. 2016;91:173–8. [PMC free article] [PubMed] [Google Scholar]

55. Hanley B, Naresh KN, Roufosse C, Nicholson AG, Weir J, Cooke GS, et al. Histopathological findings and viral tropism in UK patients with severe fatal COVID‐19: a post‐mortem study. Lancet. Microbe. 2020;1:e245–53. [PMC free article] [PubMed] [Google Scholar]

56. James J, Srivastava A, Varghese MV, Eccles CA, Zemskova M, Rafikova O, et al. Heme induces rapid endothelial barrier dysfunction via the MKK3/p38MAPK axis. Blood. 2020;136:749–54. [PMC free article] [PubMed] [Google Scholar]

57. Gheblawi M, Wang K, Viveiros A, Nguyen Q, Zhong JC, Turner AJ, et al. Angiotensin‐Converting Enzyme 2: SARS‐CoV‐2 Receptor and Regulator of the Renin‐Angiotensin System: Celebrating the 20th Anniversary of the Discovery of ACE2. Circ Res. 2020;126:1456–74. [PMC free article] [PubMed] [Google Scholar]

58. Grimes JM, Grimes KV. p38 MAPK inhibition: a promising therapeutic approach for COVID‐19. J Mol Cell Cardiol. 2020;144:63–5. [PMC free article] [PubMed] [Google Scholar]

59. Schots R, Kaufman L, Van Riet I, Ben Othman T, De Waele M, Van Camp B, et al. Proinflammatory cytokines and their role in the development of major transplant‐related complications in the early phase after allogeneic bone marrow transplantation. Leukemia. 2003;17:1150–6. [PubMed] [Google Scholar]

60. Gugliotta L, Catani L, Vianelli N, Gherlinzoni F, Miggiano MC, Bandini G, et al. High plasma levels of tumor necrosis factor‐alpha may be predictive of veno‐occlusive disease in bone marrow transplantation. Blood. 1994;83:2385–6. [PubMed] [Google Scholar]

61. Symington FW, Symington BE, Liu PY, Viguet H, Santhanam U, Sehgal PB. The relationship of serum IL‐6 levels to acute graft‐versus‐host disease and hepatorenal disease after human bone marrow transplantation. Transplantation. 1992;54:457–62. [PubMed] [Google Scholar]

62. Remberger M, Ringden O. Serum levels of cytokines after bone marrow transplantation: increased IL‐8 levels during severe veno‐occlusive disease of the liver. Eur J Haematol. 1997;59:254–62. [PubMed] [Google Scholar]

63. Palomo M, Diaz‐Ricart M, Rovira M, Escolar G, Carreras E. Defibrotide prevents the activation of macrovascular and microvascular endothelia caused by soluble factors released to blood by autologous hematopoietic stem cell transplantation. Biol Blood Marrow Transplant. 2011;17:497–506. [PubMed] [Google Scholar]

64. Li X, Ma X. The role of heparin in sepsis: much more than just an anticoagulant. Br J Haematol. 2017;179:389–98. [PubMed] [Google Scholar]

65. Shi C, Wang C, Wang H, Yang C, Cai F, Zeng F, et al. The potential of low molecular weight heparin to mitigate cytokine storm in severe COVID‐19 patients: a retrospective clinical study. Clin Transl Sci. 2020;13:1087–95. [PMC free article] [PubMed] [Google Scholar]

66. Lindahl U, Li JP. Heparin – an old drug with multiple potential targets in Covid‐19 therapy. J Thromb Haemost. 2020;18:2422–2424. [PMC free article] [PubMed] [Google Scholar]

67. Agelidis A, Deepak S. Heparanase, heparan sulfate and viral infection. Adv Exp Med Biol. 2020;1221:759–70. [PubMed] [Google Scholar]

68. Mycroft‐West C, Su D, Elli S, Guimond S, Miller G, Turnbull J, et al.The 2019 coronavirus (SARS‐CoV‐2) surface protein (Spike) S1 receptor binding domain undergoes conformational change upon heparin binding. bioRxiv 2020; 2020.02.29.971093.

69. Hondermarck H, Bartlett NW, Nurcombe V. The role of growth factor receptors in viral infections: an opportunity for drug repurposing against emerging viral diseases such as COVID‐19? FASEB Bioadv. 2020;2:296–303. [PMC free article] [PubMed] [Google Scholar]

70. Clausen TM, Sandoval DR, Spliid CB, Pihl J, Perrett HR, Painter CD, et al. SARS‐CoV‐2 infection depends on cellular heparan sulfate and ACE2. Cell. 2020;183:1043–57. [PMC free article] [PubMed] [Google Scholar]

71. Khanna M, Ranasinghe C, Browne AM, Li JP, Vlodavsky I, Parish CR. Is host heparanase required for the rapid spread of heparan sulfate binding viruses? Virology. 2019;529:1–6. [PubMed] [Google Scholar]

72. Hadigal SR, Agelidis AM, Karasneh GA, Antoine TE, Yakoub AM, Ramani VC, et al. Heparanase is a host enzyme required for herpes simplex virus‐1 release from cells. Nat Commun. 2015;6:6985. [PMC free article] [PubMed] [Google Scholar]

73. Agelidis AM, Hadigal SR, Jaishankar D, Shukla D. Viral activation of Heparanase drives pathogenesis of herpes simplex virus‐1. Cell Rep. 2017;20:439–50. [PMC free article] [PubMed] [Google Scholar]

74. Koganti R, Suryawanshi R, Shukla D. Heparanase, cell signaling, and viral infections. Cell Mol Life Sci. 2020;77:5059–77. [PMC free article] [PubMed] [Google Scholar]

75. Goodall KJ, Poon IK, Phipps S, Hulett MD. Soluble heparan sulfate fragments generated by heparanase trigger the release of pro‐inflammatory cytokines through TLR‐4. PLoS One. 2014;9:e109596. [PMC free article] [PubMed] [Google Scholar]

76. Mayfosh AJ, Baschuk N, Hulett MD. Leukocyte heparanase: a double‐edged sword in tumor progression. Front Oncol. 2019;9:331. [PMC free article] [PubMed] [Google Scholar]

77. Seifert C, Wittig S, Arndt C, Gruhn B. Heparanase polymorphisms: influence on incidence of hepatic sinusoidal obstruction syndrome in children undergoing allogeneic hematopoietic stem cell transplantation. J Cancer Res Clin Oncol. 2015;141:877–85. [PubMed] [Google Scholar]

78. Palmer KJ, Defibrotide GK. A review of its pharmacodynamic and pharmacokinetic properties, and therapeutic use in vascular disorders. Drugs. 1993;45:259–94. [PubMed] [Google Scholar]

79. Thiemermann C, Thomas GR, Vane JR. Defibrotide reduces infarct size in a rabbit model of experimental myocardial ischaemia and reperfusion. Br J Pharmacol. 1989;97:401–8. [PMC free article] [PubMed] [Google Scholar]

80. Stein C, Castanotto D, Krishnan A, Nikolaenko L. Defibrotide (Defitelio): a new addition to the stockpile of food and drug administration‐approved oligonucleotide drugs. Mol Ther Nucleic Acids. 2016;5:e346. [PMC free article] [PubMed] [Google Scholar]

81. Pescador R, Mantovani M, Prino G, Madonna M. Pharmacokinetics of Defibrotide and of its profibrinolytic activity in the rabbit. Thromb Res. 1983;30:1–11. [PubMed] [Google Scholar]

82. Falanga A, Vignoli A, Marchetti M, Barbui T. Defibrotide reduces procoagulant activity and increases fibrinolytic properties of endothelial cells. Leukemia. 2003;17:1636–42. [PubMed] [Google Scholar]

83. Cella G, Sbarai A, Mazzaro G, Motta G, Carraro P, Andreozzi GM, et al. Tissue factor pathway inhibitor release induced by defibrotide and heparins. Clin Appl Thromb Hemost. 2001;7:225–8. [PubMed] [Google Scholar]

84. Echart CL, Graziadio B, Somaini S, Ferro LI, Richardson PG, Fareed J, et al. The fibrinolytic mechanism of defibrotide: effect of defibrotide on plasmin activity. Blood Coagul Fibrinolysis. 2009;20:627–34. [PubMed] [Google Scholar]

85. Niada R, Mantovani M, Prino G, Pescador R, Berti F, Omini C, et al. Antithrombotic activity of a polydeoxyribonucleotidic substance extracted from mammalian organs: a possible link with prostacyclin. Thromb Res. 1981;23:233–46. [PubMed] [Google Scholar]

86. Francischetti IM, Oliveira CJ, Ostera GR, Yager SB, Debierre‐Grockiego F, Carregaro V, et al. Defibrotide interferes with several steps of the coagulation‐inflammation cycle and exhibits therapeutic potential to treat severe malaria. Arterioscler Thromb Vasc Biol. 2012;32:786–98. [PMC free article] [PubMed] [Google Scholar]

87. U.S. Food & Drug Administration (FDA) . Defitelio (defibrotide sodium). Available at: https://www.fda.gov/drugs/resources‐information‐approved‐drugs/defitelio‐defibrotide‐sodium. Accessed January 2021

88. Richardson PG, Riches ML, Kernan NA, Brochstein JA, Mineishi S, Termuhlen AM, et al. Phase 3 trial of defibrotide for the treatment of severe veno‐occlusive disease and multi‐organ failure. Blood. 2016;127:1656–65. [PMC free article] [PubMed] [Google Scholar]

89. Richardson PG, Grupp SA, Pagliuca A, Krishnan A, Ho VT, Corbacioglu S. Defibrotide for the treatment of hepatic veno‐occlusive disease/sinusoidal obstruction syndrome with multiorgan failure. Int J Hematol Oncol. 2017;6:75–93. [PMC free article] [PubMed] [Google Scholar]

90. Richardson PG, Soiffer RJ, Antin JH, Uno H, Jin Z, Kurtzberg J, et al. Defibrotide for the treatment of severe hepatic veno‐occlusive disease and multiorgan failure after stem cell transplantation: a multicenter, randomized, dose‐finding trial. Biol Blood Marrow Transplant. 2010;16:1005–17. [PMC free article] [PubMed] [Google Scholar]

91. Richardson PG, Murakami C, Jin Z, Warren D, Momtaz P, Hoppensteadt D, et al. Multi‐institutional use of defibrotide in 88 patients after stem cell transplantation with severe veno‐occlusive disease and multisystem organ failure: response without significant toxicity in a high‐risk population and factors predictive of outcome. Blood. 2002;100:4337–43. [PubMed] [Google Scholar]

92. Corbacioglu S, Cesaro S, Faraci M, Valteau‐Couanet D, Gruhn B, Rovelli A, et al. Defibrotide for prophylaxis of hepatic veno‐occlusive disease in paediatric haemopoietic stem‐cell transplantation: an open‐label, phase 3, randomised controlled trial. Lancet. 2012;379:1301–9. [PubMed] [Google Scholar]

93. Palomo M, Mir E, Rovira M, Escolar G, Carreras E, Diaz‐Ricart M. What is going on between defibrotide and endothelial cells? Snapshots reveal the hot spots of their romance. Blood. 2016;127:1719–27. [PMC free article] [PubMed] [Google Scholar]

94. Schröder H. Defibrotide protects endothelial cells, but not L929 tumour cells, from tumour necrosis factor‐alpha‐mediated cytotoxicity. J Pharm Pharmacol. 1995;47:250–2. [PubMed] [Google Scholar]

95. Mitsiades CS, Rouleau C, Echart C, Menon K, Teicher B, Distaso M, et al. Preclinical studies in support of defibrotide for the treatment of multiple myeloma and other neoplasias. Clin Cancer Res. 2009;15:1210–21. [PMC free article] [PubMed] [Google Scholar]

96. Eissner G, Multhoff G, Gerbitz A, Kirchner S, Bauer S, Haffner S, et al. Fludarabine induces apoptosis, activation, and allogenicity in human endothelial and epithelial cells: protective effect of defibrotide. Blood. 2002;100:334–40. [PubMed] [Google Scholar]

97. Ferraresso M, Rigotti P, Stepkowski SM, Chou TC, Kahan BD. Immunosuppressive effects of defibrotide. Transplantation. 1993;56:928–33. [PubMed] [Google Scholar]

98. Scalia R, Kochilas L, Campbell B, Lefer AM. Effects of defibrotide on leukocyte‐endothelial cell interaction in the rat mesenteric vascular bed: role of P‐selectin. Methods Find Exp Clin Pharmacol. 1996;18:669–76. [PubMed] [Google Scholar]

99. García‐Bernal D, Palomo M, Martínez CM, Millán‐Rivero JE, García‐Guillén AI, Blanquer M, et al. Defibrotide inhibits donor leucocyte‐endothelial interactions and protects against acute graft‐versus‐host disease. J Cell Mol Med. 2020;24:8031–44. [PMC free article] [PubMed] [Google Scholar]

100. Bianchi G, Barone D, Lanzarotti E, Tettamanti R, Porta R, Moltrasio D, et al. Defibrotide, a single‐stranded polydeoxyribonucleotide acting as an adenosine receptor agonist. Eur J Pharmacol. 1993;238:327–34. [PubMed] [Google Scholar]

101. Ko IG, Hwang JJ, Chang BS, Kim SH, Jin JJ, Hwang L, et al. Polydeoxyribonucleotide ameliorates lipopolysaccharide‐induced acute lung injury via modulation of the MAPK/NF‐κB signaling pathway in rats. Int Immunopharmacol. 2020;83:106444. [PubMed] [Google Scholar]

102. Richardson PG, Carreras E, Iacobelli M, Nejadnik B. The use of defibrotide in blood and marrow transplantation. Blood Adv. 2018;2:1495–509. [PMC free article] [PubMed] [Google Scholar]

103. Tekgündüz E, Kaya AH, Bozdağ SC, Koçubaba Ş, Kayıkçı Ö, Namdaroğlu S, et al. Does defibrotide prophylaxis decrease the risk of acute graft versus host disease following allogeneic hematopoietic cell transplantation? Transfus Apher Sci. 2016;54:30–4. [PubMed] [Google Scholar]

104. Yeates L, Slatter MA, Bonanomi S, Lim FL, Ong SY, Dalissier A, et al. Use of defibrotide to treat transplant‐associated thrombotic microangiopathy: a retrospective study of the Paediatric Diseases and Inborn Errors Working Parties of the European Society of Blood and Marrow Transplantation. Bone Marrow Transplant. 2017;52:762–4. [PubMed] [Google Scholar]

105. Nadir Y. Heparanase in the coagulation system. Adv Exp Med Biol. 2020;1221:771–84. [PubMed] [Google Scholar]

106. Buijsers B, Yanginlar C, Grondman I, de Nooijer A, Maciej‐Hulme ML, Jonkman I, et al. Increased plasma heparanase activity in COVID‐19 patients. medRxiv. 2020;2020.06.12.20129304. [PMC free article] [PubMed] [Google Scholar]

107. Klein OR, Choi S, Haile A, Ktena YP, Pierce E, Smith M, et al. Defibrotide Modulates Pulmonary Endothelial Cell Activation and Protects Against Lung Inflammation in Pre‐Clinical Models of LPS‐Induced Lung Injury and Idiopathic Pneumonia. Syndrome. 2020;26:S138–9. [Google Scholar]

108. Richardson E, Carlo‐Stella C, Jara R, Vlodavsky I, Iacobelli M, Fareed J, et al. Response to Maccio et al., “Multifactorial Pathogenesis of COVID‐19‐related Coagulopathy: Can defibrotide have a role in the early phases of coagulation disorders?. J Thromb Haemost. 2020;18:3111–3. [PubMed] [Google Scholar]

109. Lang P, Eichholz T, Bakchoul T, Streiter M, Petrasch M, Bösmüller H, et al. Defibrotide for the treatment of PIMS‐TS in two pediatric patients. J Pediatr Infect Dis Soc. 2020;9:622–5. [Google Scholar]

110. Chen S, He Y, Hu Z, Lu S, Yin X, Ma X, et al. Heparanase Mediates Intestinal Inflammation and Injury in a Mouse Model of Sepsis. J Histochem Cytochem. 2017;65:241–9. [PMC free article] [PubMed] [Google Scholar]

111. Huang X, Han S, Liu X, Wang T, Xu H, Xia B, et al. Both UFH and NAH alleviate shedding of endothelial glycocalyx and coagulopathy in LPS‐induced sepsis. Exp Ther Med. 2020;19:913–22. [PMC free article] [PubMed] [Google Scholar]

112. Masola V, Bellin G, Vischini G, Dall’Olmo L, Granata S, Gambaro G, et al. Inhibition of heparanase protects against chronic kidney dysfunction following ischemia/reperfusion injury. Oncotarget. 2018;9:36185–201. [PMC free article] [PubMed] [Google Scholar]

113. Koliesnik IO, Kuipers HF, Medina CO, Zihsler S, Liu D, Van Belleghem JD, et al. The heparan sulfate mimetic PG545 modulates T cell responses and prevents delayed‐type hypersensitivity. Front Immunol. 2020;11:132. [PMC free article] [PubMed] [Google Scholar]

114. Abassi Z, Hamoud S, Hassan A, Khamaysi I, Nativ O, Heyman SN, et al. Involvement of heparanase in the pathogenesis of acute kidney injury: nephroprotective effect of PG545. Oncotarget. 2017;8:34191–204. [PMC free article] [PubMed] [Google Scholar]

115. Ostapoff KT, Awasthi N, Cenik BK, Hinz S, Dredge K, Schwarz RE, et al. PG545, an angiogenesis and heparanase inhibitor, reduces primary tumor growth and metastasis in experimental pancreatic cancer. Mol Cancer Ther. 2013;12:1190–201. [PubMed] [Google Scholar]

116. Guimond SE, Mycroft‐West CJ, Gandhi NS, Tree JA, Buttigieg KR, Coombes N, et al. Pixatimod (PG545), a clinical‐stage heparan sulfate mimetic, is a potent inhibitor of the SARS‐CoV‐2 virus. bioRxiv. 2020;2020.06.24.169334. [Google Scholar]

The coagulopathy, endotheliopathy, and vasculitis of COVID-19

Authors: Toshiaki Iba 1Jean Marie Connors 2Jerrold H Levy 3

Abstract

Background

COVID-19-associated coagulopathy (CAC) characterized by the elevated D-dimer without remarkable changes of other global coagulation markers is associated with various thrombotic complications and disease severity. The purpose of this review is to elucidate the pathophysiology of this unique coagulopathy.

Methods

The authors performed online search of published medical literature through PubMed using the MeSH (Medical Subject Headings) term “COVID-19,” “SARS-CoV-2,” “coronavirus,” “coagulopathy,” and “thrombus.” Then, selected 51 articles that closely relevant to coagulopathy in COVID-19.

Results

The primary targets of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are the pneumocytes, immune cells, and vascular endothelial cells. The alveolar damage and the pulmonary microvascular thrombosis are the major causes of acute lung injury in COVID-19. The endotheliopathy that occurs is due to direct SARS-CoV-2 infection and activation of other pathways that include the immune system and thromboinflammatory responses leading to what is termed CAC. As a result, both microvascular and macrovascular thrombotic events occur in arterial, capillary, venule, and large vein vascular beds to produce multiorgan dysfunction and thrombotic complications. In addition to the endothelial damage, SARS-CoV-2 also can cause vasculitis and presents as a systemic inflammatory vascular disease. Clinical management of COVID-19 includes anticoagulation but novel therapies for endotheliopathy, hypercoagulability, and vasculitis are needed.

Conclusion

The endotheliopathy due to direct endothelial infection with SARS-COV-2 and the indirect damage caused by inflammation play the predominant role in the development of CAC. The intensive control of thromboinflammation is necessary to improve the outcome of this highly detrimental contagious disease.

Introduction

Ongoing reports have described the hypercoagulability and thrombotic tendency in COVID-19 [1]. The high incidence of deep vein thrombosis and pulmonary embolism has focused on the critical role of routine antithrombotic prophylaxis for COVID-19 management, especially in critically ill patients and/or elevated D-dimer levels [2,3,4]. Current reports of venous and arterial thrombotic events in the patients treated in ICU is up to 30% even with pharmacological thromboprophylaxis, and thrombotic events are associated with 5.4 times higher risk of mortality [5]. Recent postmortem evaluation of COVID-19 patients has demonstrated severe endothelial injury with cellular death/apoptosis, and the presence of intracellular virus in the autopsy lung with thrombosis and small to middle-size pulmonary vessels. The clotting and vascular damage were also confirmed in the alveolar capillary and these changes are more remarkable in COVID-19 compared to influenza induced lung injury [6]. In this summary, we will review the pathophysiology of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-induced endotheliopathy, COVID-19-associated coagulopathy (CAC), and vasculitis.

Coagulopathy in COVID-19

The mechanism of coagulopathy in COVID-19

Thromboembolic complications are the hallmark of COVID-19 that can cause death even in asymptomatic COVID-19 [7]. The new coronavirus SARS-CoV-2 elicits an acute inflammatory effect with hypercoagulability, platelet activation, and endothelial dysfunction [8]. Although, this presentation has similarities with sepsis-induced coagulopathy (SIC) due to bacterial infections and disseminated intravascular coagulation (DIC), there are several important differences [8]. In CAC, patients often initially present with increased fibrinogen levels, increased D-dimers, but minor changes in prothrombin time and platelet count compared to acute bacterial sepsis that can produce thrombocytopenia, prolonged prothrombin times, and decreased antithrombin levels [49]. It is also known that inflammatory cytokine levels are elevated in COVID-19 and excess production of inflammatory cytokines can induce hemophagocytic lymphohistiocytosis (HLH)/macrophage activation syndrome (MAS) that can result in a thrombotic coagulation disorder [10]. Although the pathophysiology of HLH/MAS seems similar to COVID-19, the reported cytokine level is much lower in COVID-19 [11]. Conversely, the endothelial derangement, detailed in the next section, is predominant in COVID-19. Other than HLH/MAS, various thrombotic diseases such as thrombotic microangiopathy, and antiphospholipid syndrome can occur, and the characteristics of these diseases look similar to CAC [12]. Even though the pathogeneses of these thrombotic diseases partially overlap with CAC, it is important to delineate the unique statue of CAC to plan a therapeutic strategy.

The evaluation of COVID-19-associated coagulopathy

D-Dimer monitoring is important in COVID-19 coagulopathy. Although D-dimer is initially elevated, other conventional coagulation laboratory tests including prothrombin time (PT), activated partial thromboplastin time (aPTT), and platelet count are often normal, and are not useful indicators of the thrombotic risk. The increase of factor VIII and von Willebrand factor (VWF) [13], potentially the presence of antiphospholipid antibodies [14], and increased activity of complement system are also reported, however, monitoring these biomarkers is not practical. The pathogenesis of coagulopathy in COVID-19 is complex but the typical CAC can be diagnosed by increased D-dimer, elevated fibrinogen and VWF levels, but relatively normal PT, aPTT, and platelet count. A pathway for diagnosing CAC versus other coagulopathies is illustrated in Fig. 1.

figure 1
Fig. 1

Thrombin generation testing (TGT) measures ex vivo thrombin formation in plasma upon activation with tissue factor. TGT allows calculation of peak and total thrombin generation, as well as time to initial and peak thrombin generation. This assay can identify both reduced and increased thrombin generation. Nougier et al. [15] revealed increased thrombin generation in COVID-19 patients despite undergone anticoagulation. The major drawbacks of TGT are the lack of standardization and the requirement of technical training.

Other potential assays to assess global coagulation status include viscoelastic testing, especially in ICU patients, as a point of care test. An increasing number of studies report hypercoagulability as indicated by decreased R or clot times, and increased maximal amplitude/maximal clot firmness by viscoelastic monitoring [16,17,18]. However, these changes are consistent with high fibrinogen levels that affect both maximal amplitude on thromboelastography (TEG), and maximum clot firmness on rotational thromboelastometry (ROTEM). Ranucci et al. [17] reported the median fibrinogen level was nearly 800 mg/dL in the COVID-19 patients treated in ICU, and such a high fibrinogen level affects TEG and ROTEM parameters considerably by itself [19].

Endotheliopathy in COVID-19

The endothelial damage and thrombosis

An important feature of CAC is the microcirculatory endothelial damage in pulmonary circulation and other vascular beds. Since SARS-CoV-2 directly infects the vascular endothelial cell causing cellular damage and apoptosis, the antithrombotic activity of the luminal surface is remarkably decreased [20]. In COVID-19, both alveolar damage and microcirculatory disturbance associated with thrombus formation contribute to respiratory dysfunction. At autopsy, findings reported include clot formation in pulmonary arterioles with diffuse alveolar damage and hyaline membranes [21]. Normal endothelial function refers to the ability of regulating vascular tonus, permeability, cell adhesion, and anticoagulation. Healthy endothelial cells synthesize nitric oxide (NO) by conversion of L-arginine to L-citrulline by nitric oxide synthase. NO released by endothelium prevents leukocyte and platelet adhesion, inflammatory cell migration into the vessel wall, smooth muscle cell proliferation, and suppresses apoptosis and inflammation. SARS-Cov-2 enters endothelial cells through endocytosis and is mediated by an interplay of Angiotensin-converting enzyme 2 (ACE2) and the transmembrane protease serine 2 (TMPRSS-2) which sheds a part of spike protein and helps SARS-Cov-2 to enter into endothelial cell. The infected endothelial cells lose their ability to maintain aforementioned physiological functions. Subsequently, the damage of the endothelium leads to the procoagulant change of the vascular lumen, formation of immunothrombosis, and organ malcirculation.

Both systemic pulmonary microthrombosis and thromboembolism are commonly seen in COVID-19. This typical figure is thought to be the result of hypercoagulability due to the dysregulated endothelial function of the pulmonary vessels and systemic inflammation. In addition to the deep vein thrombus that results in an embolic event, in situ formation in the pulmonary arteries can be the main reason of pulmonary dysfunction. Lax et al. [22] performed autopsies in 11 patients and reported that despite the absence of clinical presentations of thromboembolism, thrombus formation in small and mid-sized pulmonary arteries was found in all of the examined cases. In these cases, thrombus is suspected to form at the peripheral arteriole and elongate proximally. According to another series of autopsy findings, the incidence of thrombus formation in the pulmonary microvasculature is approximately nine times higher than that seen in influenza [6].

The endothelial damage-derived hypercoagulability

ACE2, the host cellular receptor of SARS-CoV-2, has been identified on the vascular endothelial surface. SARS-CoV-2 uses ACE2 to invade into the cell through the fusion of its membrane to the host cell membrane. As a result, the host cell loses ACE2 activity which subsequently leads to reduced angiotensin II inactivation and decreased conversion to antiotensin1-7. Increased angiotensin II stimulates vascular constriction and decreased antiotensin1-7 suppresses nitric oxide production which triggers increased thrombogenicity due to leucocyte and platelet adhesion and vasoconstriction [23].

The vascular endothelium is coated by a gel-like component known as the glycocalyx, that regulates vascular blood flow by providing an antithrombotic surface via antithrombin binding to the heparan sulfate constituents, a major component of the glycocalyx. Although the circulating antithrombin level has been reported to be in a normal range on presentation in COVID-19 cases [13], if the glycocalyx is disrupted, the local antithrombogenicity of the endothelial surface may be altered. However, little information on the glycocalyx status in COVID-19 is available.

One of the unique features of CAC is the increase in VWF and factor VIII [1324] and it is suggested to be the result of vascular response to SARS-CoV-2 infection. VWF and factor VIII are stored in the Weibel-Palade body of endothelial cells and released in response to infectious stimuli [25] (Fig. 2). The increase in VWF suggests a possible similarity to thrombotic thrombocytopenic purpura, however, ADAMTS13 (a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13) levels in COVID-19 although reported to be decreased, may not be severely depleted as in thrombotic thrombocytopenic purpura [26]. The increased VWF levels to 3–4 times normal values seen in patients with COVID-19 may overwhelm the ADAMTS13 activity to degrade the ultra large VWF multimers. The importance of circulating VWF and multimer size in CAC is not established, however, one of the suggested methods to reduce the risk of thrombotic events due to excess ultra large VWF itself is plasma exchange [2728].

figure 2
Fig. 2

Similar to factor VIII and VWF, angiopoietin 2, also stored in Weibel-Palade bodies, is known to be released and its circulating level increases in COVID-19 [29]. Angiopoietin 2 serves as an antagonist of angiopoietin 1 and inhibits anti-inflammatory, anticoagulatory, and antiapoptotic signaling induced by angiopoietin 1 by binding to Tie2 competitively [30] (Fig. 3). Tie2 activation by angiopoietin 1 also normalizes prothrombotic responses by inhibiting endothelial tissue factor and phosphatidylserine exposure in sepsis, and therefore, Tie2 signaling is considered to play a central role in the regulation of thrombus formation in SIC/DIC [31]. Angiotensin 2 is also known to increase endothelial permeability and is considered an important factor in acute respiratory distress syndrome [32]. The role of angiopoietin 2 in CAC has not been studied well and it should be the focus in future studies.

figure 3
Fig. 3

The monitoring of endothelial damage

One of the difficulties in clinical studies of endothelial research is the limited availability of ideal biomarkers. The glycocalyx provides an interface between blood flow and endothelial cells. Since the glycocalyx is fragile, its components are used as biomarkers of endothelial damage in various diseases including infectious diseases [30]. One such biomarker is a hyaluronic acid, a major glycocalyx component. Circulating levels of hyaluronic acid, are elevated in critically ill COVID-19 patients compared with less severe cases [33]. Other than that, the proteins that are released from the Weibel-Palade body i.e., VWF, FVIII, and P-selectin are the potential biomarkers. In addition, sensitive coagulation markers such as thrombin-antithrombin complex (TAT) and prothrombin fragment 1 + 2 can be a marker for the microthrombosis. Goshua et al. [34] reported VWF antigen/antibody, FVIII activity, and TAT levels are significantly higher in the more severe cases.

As previously mentioned, angiopoietin 2 is stored in the endothelial cells and secreted along with the endothelial damage. Reportedly, angiopoietin 2 levels are associated with coagulation disorder, organ damage and death in bacterial sepsis [35]. Smadja et al. [29] measured angiopoietin 2, D-dimer, CRP, and creatinine in consecutive 40 COVID-19 patients treated in ICU, and found angiopoietin 2, cut-off of 5000 pg/mL, as the best predictor for poor outcome (sensitivity: 80.1%, specificity: 70%). It is crucial to find a good biomarker of vascular damage in COVID-19 study.

Therapeutic strategies for endothelial damage

Despite prophylactic anticoagulation in CAC, patients can still develop thrombotic sequela. A recent study reported that despite systematic use of thromboprophylaxis, 31% of the COVID-19 patients treated in ICU developed thrombotic complications [36]. In another study, the cumulative incidence of arterial and venous thromboembolism was 49% [3]. These reports suggest that despite anticoagulation, additional therapy for endothelial injury is necessary to prevent thrombosis. Potential therapies include synthetic serine protease inhibitors such as nafamostat mesylate and camostat mesylate which theoretically prevent SARS-CoV-2 infection. Coronavirus gains entry to the cell using the host TMPRSS2 which cleaves the spike protein resulting in its ability to fuse to the host cellular membrane. These agents inhibit TMPRSS2 thereby abrogating the activating proteolytic processing of virus [37]. Since nafamostat mesylate also has anticoagulatory effects, it has been used for DIC and anticoagulation for extracorporeal circuits in Japan.

Other therapeutic considerations are the physiologic anticoagulants such as protein C and antithrombin. The dual action of protein C/activated protein C to inactivate factor VIIIa and upregulate ACE2 are the advantage of this system which suppress both coagulation and inflammation. Activated protein C can also reduce pulmonary injury by suppressing the macrophage inflammatory protein family chemokine response [38]. Antithrombin is another multifaceted serine protease inhibitor of multiple coagulation factors, but also protects the glycocalyx by binding to heparan sulfate [39]. Bikdeli et al. [40] noted in their recent review of pharmacological therapy targeting thromboinflammation in COVID-19, that antithrombin suppresses excess inflammation by inhibiting nuclear factor-κB, it may be suitable for the treatment of CAC. However, the effects of these agents in COVID-19 haven’t been examined in clinical trials and future study may be warranted.

Arterial thrombosis in COVID-19

Arterial thrombosis is an uncommon event in other infection-associated coagulopathies. In contrast, stroke, ischemic coronary disease, and thrombotic limb ischemia can occur in COVID-19. Lodigiani et al. [41] reported the rate of ischemic stroke and acute coronary syndrome was 2.5% and 1.1%, respectively, in Italy. Kashi et al. [42] reported two cases of floating thrombi in thoracic aorta and such cases are extremely odd in previously described infectious diseases. Antiphospholipid syndrome is known as a disease that result in arterial thrombosis and can occur secondary to infection. Some reports have shown increased lupus anticoagulant, anticardiolipin, and anti-β2-glycoprotein I antibodies, however, the presence of high titer IgG antibody, an important responsible factor, has not proven yet [132443], and the association between antiphospholipid syndrome and CAC is still unclear. The presence of unusually large VWF multimers and subsequent activation of platelets and microthrombi can explain the occurrence of arterial macrothrombosis [44], and Williams et al. [45] reported elevated VWF levels were associated with the increased risk for recurrent stroke. However, a definitive cause and effect relation has not been proven yet. The occurrence of arterial thrombosis is difficult to predict and there are no good prophylactic strategies. Oxley et al. [7] reported five cases of large-vessel stroke in patients younger than 50 years of age. The mechanism of arterial thrombosis in COVID-19 remains a mystery and prediction of the events was not possible in any of the cases; demographic factors, laboratory data, and severity of COVID-19 did not appear to be related to arterial events.

Clot formation in extracorporeal circuits

The high incidence of clot formation during extracorporeal circulation has been recognized. Helms et al. [13] studied 150 COVID-19 patients and reported 28 out of 29 patients (96.6%) receiving continuous renal replacement therapy (CRRT) experienced clotting of the circuit. The median lifespan of an CRRT circuit was 1.5 days which is only half of the recommendation duration. They also reported 12 patients (8%) were treated by extracorporeal membrane oxygenation (ECMO), and among them, thrombotic occlusions of centrifugal pump occurred in 2 patients. Methods to minimize extracorporeal circuit clotting include prefilter infusion of heparin and the use of citrate-based replacement fluid for dialysis are not always successful [46]. The reason for the high incidence of CRRT filter and ECMO oxygenator coagulation is not known, but factors other than endotheliopathy such as hypercoagulability, hypofibrinolysis, and platelet activation must attribute. The elevated VWF activity, increased factor VIII level, and high fibrinogen level may lead to microthrombi formation possibly occluding the filter. Suppressed fibrinolysis may also play a role [47], with excess angiotensin II enhancing the expression of PAI-1 in the endothelium in COVID-19 [48].

Vasculitis in COVID-19

A report from northern Italy observed significantly increased number of patients with Kawasaki disease, an acute self-limiting vasculitis predominantly involving the coronary arteries, with hemodynamically unstable Kawasaki disease shock syndrome (KDSS) during the COVID-19 pandemic [49]. It is also reported that children with COVID-19 are more likely to show MAS that resembles secondary HLH. Varga et al. [50] demonstrated the direct viral infection of the endothelial cell and diffuse endothelial inflammation which are followed by the induction of endothelitis, apoptosis, and pyroptosis in autopsy cases of COVID-19. Of note is the mononuclear cell infiltrations into the vascular intima along the lumen of many vessels also reported in this post-mortem analysis. This finding suggests that the virus can invade into human vasculature and cause vasculitis. Roncati et al. [51] estimated the escalation from type 2 T-helper immune response to type 3 hypersensitivity is involved in the pathophysiology of COVID-19-induced vasculitis. They reported the deposition of immune complexes inside the vascular walls causing more severe inflammatory reaction, and interleukin-6 is the key myokine in this scenario.

Conclusion

The mechanism of coagulopathy in COVID-19 continues to be investigated. However, the predominant role of endotheliopathy due to direct endothelial infection with SARS-COV-2 and the indirect damage caused by inflammation are part of the complex thromboinflammatory process. The elevated circulating levels of clotting factors including fibrinogen, factor VIII, VWF released from the stimulated endothelial cells, and the loss of the thromboprotective function with glycocalyx damage and decreased nitric oxide production also contribute to the coagulopathy and thromboinflammation. SARS-CoV-2 damages not only the luminal surface of the vasculature but also induce vasculitis, contributing to the significant pathology associated with COVID-19.

References

  1. 1.Han H, Yang L, Liu R. Prominent changes in blood coagulation of patients with SARS-CoV-2 infection. Clin Chem Lab Med. 2020. https://doi.org/10.1515/cclm-2020-0188.Article PubMed Google Scholar 
  2. 2.Ren B, Yan F, Deng Z, Zhang S, Xiao L, Wu M, Cai L. Extremely high incidence of lower extremity deep venous thrombosis in 48 patients with severe COVID-19 in Wuhan. Circulation. 2020. https://doi.org/10.1161/CIRCULATIONAHA.120.047407.Article PubMed Google Scholar 
  3. 3.Thachil J, Tang N, Gando S, Falanga A, Cattaneo M, Levi M, Clark C, Iba T. ISTH interim guidance on recognition and management of coagulopathy in COVID-19. J Thromb Haemost. 2020;18(5):1023–6.CAS Article Google Scholar 
  4. 4.Connors JM, Levy JH. COVID-19 and its implications for thrombosis and anticoagulation. Blood. 2020:blood.2020006000.
  5. 5.Klok FA, Kruip MJHA, van der Meer NJM, Arbous MS, Gommers D, Kant KM, Kaptein FHJ, van Paassen J, Stals MAM, Huisman MV, Endeman H. Confirmation of the high cumulative incidence of thrombotic complications in critically ill ICU patients with COVID-19: An updated analysis. Thromb Res. 2020;S0049–3848(20):30157–62.Google Scholar 
  6. 6.Ackermann M, Verleden SE, Kuehnel M, Haverich A, Welte T, Laenger F, Vanstapel A, Werlein C, Stark H, Tzankov A, Li WW, Li VW, Mentzer SJ, Jonigk D. Pulmonary vascular endothelialitis, thrombosis, and angiogenesis in Covid-19. N Engl J Med. 2020. https://doi.org/10.1056/NEJMoa2015432.Article PubMed Google Scholar 
  7. 7.Oxley TJ, Mocco J, Majidi S, Kellner CP, Shoirah H, Singh IP, De Leacy RA, Shigematsu T, Ladner TR, Yaeger KA, Skliut M, Weinberger J, Dangayach NS, Bederson JB, Tuhrim S, Fifi JT. Large-vessel stroke as a presenting feature of Covid-19 in the young. N Engl J Med. 2020;382(20):e60.Article Google Scholar 
  8. 8.Levi M, Thachil J, Iba T, Levy JH. Coagulation abnormalities and thrombosis in patients with COVID-19. Lancet Haematol. 2020;7(6):e438–e440440.Article Google Scholar 
  9. 9.Iba T, Levy JH. Sepsis-induced coagulopathy and disseminated intravascular coagulation. Anesthesiology. 2020;132(5):1238–45.Article Google Scholar 
  10. 10.McGonagle D, et al. Immune mechanisms of pulmonary intravascular coagulopathy in COVID-19 pneumonia. Lancet Rheumatol. 2020. https://doi.org/10.1016/S2665-9913(20)30121-1.Article PubMed PubMed Central Google Scholar 
  11. 11.Leisman DE, Deutschman CS, Legrand M. Facing COVID-19 in the ICU: vascular dysfunction, thrombosis, and dysregulated inflammation. Intensive Care Med. 2020;28:1–4. https://doi.org/10.1007/s00134-020-06059-6.CAS Article Google Scholar 
  12. 12.Opoka-Winiarska V, Grywalska E, Roliński J. Could hemophagocytic lymphohistiocytosis be the core issue of severe COVID-19 cases? BMC Med. 2020;18(1):214.CAS Article Google Scholar 
  13. 13.Helms J, Tacquard C, Severac F, Leonard-Lorant I, Ohana M, Delabranche X, Merdji H, Clere-Jehl R, Schenck M, Fagot Gandet F, Fafi-Kremer S, Castelain V, Schneider F, Grunebaum L, Anglés-Cano E, Sattler L, Mertes PM, Meziani F, CRICS TRIGGERSEP Group (Clinical Research in Intensive Care and Sepsis Trial Group for Global Evaluation and Research in Sepsis). High risk of thrombosis in patients with severe SARS-CoV-2 infection: a multicenter prospective cohort study. Intensive Care Med. 2020:1–10.
  14. 14.Zhang Y, Xiao M, Zhang S, Xia P, Cao W, Jiang W, Chen H, Ding X, Zhao H, Zhang H, Wang C, Zhao J, Sun X, Tian R, Wu W, Wu D, Ma J, Chen Y, Zhang D, Xie J, Yan X, Zhou X, Liu Z, Wang J, Du B, Qin Y, Gao P, Qin X, Xu Y, Zhang W, Li T, Zhang F, Zhao Y, Li Y, Zhang S. Coagulopathy and antiphospholipid antibodies in patients with Covid-19. N Engl J Med. 2020;382(17):e38.Article Google Scholar 
  15. 15.Nougier C, Benoit R, Simon M, Desmurs-Clavel H, Marcotte G, Argaud L, David JS, Bonnet A, Negrier C, Dargaud Y. Hypofibrinolytic state and high thrombin generation may play a major role in sars-cov2 associated thrombosis. J Thromb Haemost. 2020. https://doi.org/10.1111/jth.15016.Article PubMed PubMed Central Google Scholar 
  16. 16.Maatman TK, Jalali F, Feizpour C, Douglas A 2nd, McGuire SP, Kinnaman G, Hartwell JL, Maatman BT, Kreutz RP, Kapoor R, Rahman O, Zyromski NJ, Meagher AD. Routine venous thromboembolism prophylaxis may be inadequate in the hypercoagulable state of severe coronavirus disease 2019. Crit Care Med. 2020. https://doi.org/10.1097/CCM.0000000000004466.Article PubMed PubMed Central Google Scholar 
  17. 17.Ranucci M, Ballotta A, Di Dedda U, Bayshnikova E, Dei Poli M, Resta M, Falco M, Albano G, Menicanti L. The procoagulant pattern of patients with COVID-19 acute respiratory distress syndrome. J Thromb Haemost. 2020. https://doi.org/10.1111/jth.14854.Article PubMed PubMed Central Google Scholar 
  18. 18.Panigada M, Bottino N, Tagliabue P, Grasselli G, Novembrino C, Chantarangkul V, Pesenti A, Peyvandi F, Tripodi A. Hypercoagulability of COVID-19 patients in Intensive Care Unit. A report of thromboelastography findings and other parameters of hemostasis. J Thromb Haemost. 2020. https://doi.org/10.1111/jth.14850.Article PubMed Google Scholar 
  19. 19.Scala E, Coutaz C, Gomez F, Alberio L, Marcucci C. Comparison of ROTEM sigma to standard laboratory tests and development of an algorithm for the management of coagulopathic bleeding in a tertiary center. J Cardiothorac Vasc Anesth. 2020;34(3):640–9.CAS Article Google Scholar 
  20. 20.Wichmann D, Sperhake JP, Lütgehetmann M, Steurer S, Edler C, Heinemann A, Heinrich F, Mushumba H, Kniep I, Schröder AS, Burdelski C, de Heer G, Nierhaus A, Frings D, Pfefferle S, Becker H, Bredereke-Wiedling H, de Weerth A, Paschen HR, Sheikhzadeh-Eggers S, Stang A, Schmiedel S, Bokemeyer C, Addo MM, Aepfelbacher M, Püschel K, Kluge S. Autopsy findings and venous thromboembolism in patients with COVID-19. Ann Intern Med. 2020;6:M20–2003. https://doi.org/10.7326/M20-2003.Article Google Scholar 
  21. 21.Dolhnikoff M, Duarte-Neto AN, de Almeida Monteiro RA, da Silva LFF, de Oliveira EP, Nascimento Saldiva PH, Mauad T, Marcia NE. Pathological evidence of pulmonary thrombotic phenomena in severe COVID-19. J Thromb Haemost. 2020. https://doi.org/10.1111/jth.14844.Article PubMed PubMed Central Google Scholar 
  22. 22.Lax SF, Skok K, Zechner P, Kessler HH, Kaufmann N, Koelblinger C, Vander K, Bargfrieder U, Trauner M. Pulmonary arterial thrombosis in COVID-19 with fatal outcome: results from a prospective, single-center, clinicopathologic case series. Ann Intern Med. 2020. https://doi.org/10.7326/M20-2566.Article PubMed PubMed Central Google Scholar 
  23. 23.Verdecchia P, Cavallini C, Spanevello A, Angeli F. COVID-19: ACE2 centric infective disease? Hypertension. 2020. https://doi.org/10.1161/HYPERTENSIONAHA.120.15353.Article PubMed Google Scholar 
  24. 24.Escher R, Breakey N, Lämmle B. ADAMTS13 activity, von Willebrand factor, factor VIII and D-dimers in COVID-19 inpatients. Thromb Res. 2020;192:174–5.CAS Article Google Scholar 
  25. 25.Streetley J, Fonseca AV, Turner J, Kiskin NI, Knipe L, Rosenthal PB, Carter T. Stimulated release of intraluminal vesicles from Weibel–Palade bodies. Blood. 2019;133(25):2707–17.CAS Article Google Scholar 
  26. 26.Huisman A, Beun R, Sikma M, Westerink J, Kusadasi N. Involvement of ADAMTS13 and von Willebrand factor in thromboembolic events in patients infected with SARS-CoV-2. Int J Lab Hematol. 2020. https://doi.org/10.1111/ijlh.13244.Article PubMed PubMed Central Google Scholar 
  27. 27.Keith P, Day M, Perkins L, Moyer L, Hewitt K, Wells A. A novel treatment approach to the novel coronavirus: an argument for the use of therapeutic plasma exchange for fulminant COVID-19. Version 2. Crit Care. 2020;24(1):128.Article Google Scholar 
  28. 28.Zachariah U, Nair SC, Goel A, Balasubramanian KA, Mackie I, Elias E, Eapen CE. Targeting raised von Willebrand factor levels and macrophage activation in severe COVID-19: consider low volume plasma exchange and low dose steroid. Thromb Res. 2020;192:2.CAS Article Google Scholar 
  29. 29.Smadja DM, Guerin CL, Chocron R, Yatim N, Boussier J, Gendron N, Khider L, Hadjadj J, Goudot G, Debuc B, Juvin P, Hauw-Berlemont C, Augy JL, Peron N, Messas E, Planquette B, Sanchez O, Charbit B, Gaussem P, Duffy D, Terrier B, Mirault T, Diehl JL. Angiopoietin-2 as a marker of endothelial activation is a good predictor factor for intensive care unit admission of COVID-19 patients. Angiogenesis. 2020;27:1–10. https://doi.org/10.1007/s10456-020-09730-0.CAS Article Google Scholar 
  30. 30.Uchimido R, Schmidt EP, Shapiro NI. The glycocalyx: a novel diagnostic and therapeutic target in sepsis. Crit Care. 2019;23(1):16.Article Google Scholar 
  31. 31.Higgins SJ, De Ceunynck K, Kellum JA, Chen X, Gu X, Chaudhry SA, Schulman S, Libermann TA, Lu S, Shapiro NI, Christiani DC, Flaumenhaft R, Parikh SM. Tie2 protects the vasculature against thrombus formation in systemic inflammation. J Clin Invest. 2018;128(4):1471–84.Article Google Scholar 
  32. 32.Parikh SM, Mammoto T, Schultz A, Yuan HT, Christiani D, Karumanchi SA, Sukhatme VP. Excess circulating angiopoietin-2 may contribute to pulmonary vascular leak in sepsis in humans. Version 2. PLoS Med. 2006;3(3):e46.Article Google Scholar 
  33. 33.Ding M, Zhang Q, Li Q, Wu T, Huang YZ. Correlation analysis of the severity and clinical prognosis of 32 cases of patients with COVID-19. Respir Med. 2020;167:105981.Article Google Scholar 
  34. 34.Goshua G, Pine AB, Meizlish ML, Chang CH, Zhang H, Bahel P, Baluha A, Bar N, Bona RD, Burns AJ, Dela Cruz CS, Dumont A, Halene S, Hwa J, Koff J, Menninger H, Neparidze N, Price C, Siner JM, Tormey C, Rinder HM, Chun HJ, Lee AI. Endotheliopathy in COVID-19-associated coagulopathy: evidence from a single-centre, cross-sectional study. Lancet Haematol. 2020;7(8):e575–e582582.Article Google Scholar 
  35. 35.Fisher J, Douglas JJ, Linder A, Boyd JH, Walley KR, Russell JA. Elevated plasma angiopoietin-2 levels are associated with fluid overload, organ dysfunction, and mortality in human septic shock. Crit Care Med. 2016;44(11):2018–27.CAS Article Google Scholar 
  36. 36.Klok FA, Kruip MJHA, van der Meer NJM, Arbous MS, Gommers DAMPJ, Kant KM, Kaptein FHJ, van Paassen J, Stals MAM, Huisman MV, Endeman H. Incidence of thrombotic complications in critically ill ICU patients with COVID-19. Thromb Res. 2020:S0049-3848(20)30120-1.
  37. 37.Yamaya M, Nishimura H, Deng X, Kikuchi A, Nagatomi R. Protease inhibitors: candidate drugs to inhibit severe acute respiratory syndrome coronavirus 2 replication. Tohoku J Exp Med. 2020;251(1):27–30.CAS Article Google Scholar 
  38. 38.Richardson MA, Gupta A, O’Brien LA, Berg DT, Gerlitz B, Syed S, Sharma GR, Cramer MS, Heuer JG, Galbreath EJ, Grinnell BW. Treatment of sepsis-induced acquired protein C deficiency reverses Angiotensin-converting enzyme-2 inhibition and decreases pulmonary inflammatory response. J Pharmacol Exp Ther. 2008;325(1):17–26.CAS Article Google Scholar 
  39. 39.Iba T, Levy JH, Hirota T, et al. Protection of the endothelial glycocalyx by antithrombin in an endotoxin-induced rat model of sepsis. Thromb Res. 2018;171:1–6.CAS Article Google Scholar 
  40. 40.Bikdeli B, Madhavan MV, Gupta A, Jimenez D, Burton JR, Der Nigoghossian C, Chuich T, Nouri SN, Dreyfus I, Driggin E, Sethi S, Sehgal K, Chatterjee S, Ageno W, Madjid M, Guo Y, Tang LV, Hu Y, Bertoletti L, Giri J, Cushman M, Quéré I, Dimakakos EP, Gibson CM, Lippi G, Favaloro EJ, Fareed J, Tafur AJ, Francese DP, Batra J, Falanga A, Clerkin KJ, Uriel N, Kirtane A, McLintock C, Hunt BJ, Spyropoulos AC, Barnes GD, Eikelboom JW, Weinberg I, Schulman S, Carrier M, Piazza G, Beckman JA, Leon MB, Stone GW, Rosenkranz S, Goldhaber SZ, Parikh SA, Monreal M, Krumholz HM, Konstantinides SV, Weitz JI, Lip GYH, Global COVID-19 Thrombosis Collaborative Group. Pharmacological agents targeting thromboinflammation in COVID-19: review and implications for future research. Thromb Haemost. 2020. https://doi.org/10.1055/s-0040-1713152.Article PubMed PubMed Central Google Scholar 
  41. 41.Lodigiani C, Iapichino G, Carenzo L, Cecconi M, Ferrazzi P, Sebastian T, Kucher N, Studt JD, Sacco C, Alexia B, Sandri MT, Barco S, Humanitas COVID-19 Task Force. Venous and arterial thromboembolic complications in COVID-19 patients admitted to an academic hospital in Milan, Italy. Thromb Res. 2020;191:9–14.CAS Article Google Scholar 
  42. 42.Escher R, Breakey N, Lämmle B. Severe COVID-19 infection associated with endothelial activation. Thromb Res. 2020;190:62.CAS Article Google Scholar 
  43. 43.Connell NT, Battinelli EM, Connors JM. Coagulopathy of COVID-19 and antiphospholipid antibodies. J Thromb Haemost. 2020. https://doi.org/10.1111/jth.14893.Article PubMed PubMed Central Google Scholar 
  44. 44.Chang JC. Acute respiratory distress syndrome as an organ phenotype of vascular microthrombotic disease: based on hemostatic theory and endothelial molecular pathogenesis. Clin Appl Thromb Hemost. 2019;25:1076029619887437.CAS Article Google Scholar 
  45. 45.Williams SR, Hsu FC, Keene KL, Chen WM, Dzhivhuho G, Rowles JL 3rd, Southerland AM, Furie KL, Rich SS, Worrall BB, Sale MM. Genetic drivers of von Willebrand factor levels in an ischemic stroke population and association with risk for recurrent stroke. Stroke. 2017;48(6):1444–500.CAS Article Google Scholar 
  46. 46.Sise ME, Baggett MV, Shepard JO, Stevens JS, Rhee EP. Case 17–2020: a 68-year-old man with Covid-19 and acute kidney injury. N Engl J Med. 2020;382(22):2147–56.Article Google Scholar 
  47. 47.Wright FL, Vogler TO, Moore EE, Moore HB, Wohlauer MV, Urban S, Nydam TL, Moore PK, McIntyre RC Jr. Fibrinolysis shutdown correlates to thromboembolic events in severe COVID-19 infection. J Am Coll Surg. 2020;S1072–7515(20):30400–2.Google Scholar 
  48. 48.Kwaan HC. Coronavirus disease 2019: the role of the fibrinolytic system from transmission to organ injury and sequelae. Semin Thromb Hemost. 2020. https://doi.org/10.1055/s-0040-1709996.Article PubMed PubMed Central Google Scholar 
  49. 49.Verdoni L, Mazza A, Gervasoni A, Martelli L, Ruggeri M, Ciuffreda M, Bonanomi E, D’Antiga L. An outbreak of severe Kawasaki-like disease at the Italian epicentre of the SARS-CoV-2 epidemic: an observational cohort study. Lancet. 2020. https://doi.org/10.1016/S0140-6736(20)31103-X.Article PubMed PubMed Central Google Scholar 
  50. 50.Varga Z, Flammer AJ, Steiger P, Haberecker M, Andermatt R, Zinkernagel AS, Mehra MR, Schuepbach RA, Ruschitzka F, Moch H. Endothelial cell infection and endotheliitis in COVID-19. Lancet. 2020;395(10234):1417–8.CAS Article Google Scholar 
  51. 51.Roncati L, Ligabue G, Fabbiani L, Malagoli C, Gallo G, Lusenti B, Nasillo V, Manenti A, Maiorana A. Type 3 hypersensitivity in COVID-19 vasculitis. Clin Immunol. 2020;29:108487. https://doi.org/10.1016/j.clim.2020.108487.CAS Article Google Scholar 

Download references

Funding

This work was supported in part by a Grant-in-Aid for Special Research in Subsidies for ordinary expenses of private schools from The Promotion and Mutual Aid Corporation for Private Schools of Japan.

Author information

Affiliations

  1. Department of Emergency and Disaster Medicine, Juntendo University Graduate School of Medicine, 2-1-1 Hongo Bunkyo-ku, Tokyo, 113-8421, JapanToshiaki Iba
  2. Hematology Division Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, USAJean Marie Connors
  3. Department of Anesthesiology, Critical Care, and Surgery, Duke University School of Medicine, Durham, NC, USAJerrold H. Levy

Spike Proteins, COVID-19, and Vaccines

A new study further elucidates the role of spike proteins in COVID-19.

Authors: Steven Novella  May 5, 2021

A recent study looks at the effects of the SARS-CoV-2 spike proteins, showing that they can cause some of the harm of COVID-19 by themselves. This is an important advance in our understanding of the disease and hopefully will lead to new therapeutic interventions.

The spike protein is what gives the coronavirus family of viruses their name. The spikes jut out from the surface of the spherical virus, giving it a crown-like halo, hence “corona”. We have also known for a long time that the spike protein is the business end of these viruses, it is what gives the virus its ability to target, latch onto, and enter the cells that it infects. Mutations in the spike protein are also what determine different variants of SARS-CoV-2, and can alter its ability to infect and cause harm.

The new study, however, is the first to directly show that the spike proteins themselves are able to cause harm, and also confirms that COVID-19 is primarily a vascular disease that damages blood vessel walls.

What the researchers did was create a pseudovirus – a protein shell with spike proteins but no viral RNA inside. Therefore these pseudoviruses are unable to actually infect cells or replicate. The point was to isolate as much as possible the effects of the spike proteins themselves. They report:

We administered a pseudovirus expressing S protein (Pseu-Spike) to Syrian hamsters intratracheally. Lung damage was apparent in animals receiving Pseu-Spike, revealed by thickening of the alveolar septa and increased infiltration of mononuclear cells.

They had control animals with a mock virus that did not show this damage. The spike protein binds to the ACE2 receptor on cells, downregulates their function, and causes damage to the endothelium cells that line lung tissue and blood vessels. The damage is apparently caused by effects on the mitochondria (energy producing organelles) in the cells – they change their shape and have reduced function. They then reproduced these effects in vitro using a culture of lung endothelial cells exposed to the spike protein.

These results explain many of the clinical features of COVD-19. While the disease has been largely thought of as a respiratory illness, it is primarily a vascular disease. It affects the lungs, but also affects other organs in the body, and can cause strokes and blood clots. While the vascular effects of coronaviruses have long been known, this study demonstrates a clear mechanism of this injury. Knowing the precise mechanism may lead to treatments to prevent or limit the vascular damage from infection. The next step is to study exactly how downregulating the ACE2 receptor damages the mitochondria.

This study, of course, did not come out of the blue but was built on previous studies showing many of the same findings. It was known, for example, that the ACE2 receptor is important for coronavirus infection, and that it related to endothelium damage. In fact a comment to the FDA by Dr. Whelan nicely summarizes a lot of this research as of December 2020. This research, however, has raised some questions about the safety of the mRNA vaccines that produce spike proteins. To be clear, the safety data on the Pfizer and Moderna mRNA vaccines are now extensive, with hundreds of millions of doses give and months of data, without any significant side effects apparent.

The Pfizer and Moderna vaccines produce the full-length spike protein. Pfizer studied several formulations initially, but found that the full length protein vaccine had fewer side effects and was better tolerated than other vaccine candidates, so that is the one they went with. It is also likely that the full protein contains more epitopes (sites for immune activity) and therefore produces more thorough and longer lasting immunity. The proteins, however, are in a fixed state, they are unable to change their confirmation, which is necessary to bind to cells. So they function differently than spike proteins on infecting virus.

After the Pfizer vaccine full spike proteins are expressed on the vaccinated cells for presentation to the immune system. But the vaccine-induced proteins do not appear to cause any harmful effects. This may be because the vaccine is administered in the muscle, and so muscle cells are the ones taking up the mRNA and making spike proteins. There is a vigorous immune response which neutralizes the spike proteins before they can cause any harm. This is very different from a virus replicating throughout the body.

Unfortunately, the complexity of COVID, mRNA, immunity, and vaccines is such that those who wish to raise fears about the vaccine can exploit partial information. There is a tremendous amount of misinformation about the COVID vaccines, and the mRNA vaccines in particularly, which then has to be constantly rebutted and debunked. That has become almost a full-time job for David Gorski here at SBM. Meanwhile, there is legitimate complexity and concerns that scientists need to carefully sort out, which they are doing, transparently and vigorously.

It’s important not to confuse not knowing everything with knowing nothing. The safety data on the mRNA vaccines is robust. Most vaccine serious side effects occur within six weeks, which is why the FDA wanted at least 6 weeks of safety data before giving the vaccines an EUA. We now have more than 6 months of data, including several months with millions of doses. It is very unlikely there are any surprises still in store with either of the mRNA vaccines. The risk is vanishingly small, while the benefit is clear.

13 ways that the SARS-CoV-2 spike protein causes damage

Authors: Posted on January 13, 2022 by Jesse Santiano, M.D.

The SARS-CoV-2 virus has four structural proteins. The spike, membrane, envelop, and nucleocapsid proteins. The spike protein protrudes from the middle of the coronavirus and attaches to the ACE2 receptor of cells to start the process of cell entry, replication, and infection. The two major parts of the spike protein are the S1 and S2 subunit. The S1 has the receptor-binding domain.

For easier reading, this review starts with what happens after the COVID jabs, soluble spike proteins, and what it takes to have a normal blood vessel. Then I will enumerate how the spike protein damages the body.

What happens after the COVID shots?

COVID vaccination aims to produce an immune response against the spike protein in the form of neutralizing antibodies so that in future SARS-CoV-2 exposures, COVID-19 will be prevented.

The injected messenger RNA provides instructions to the cells on making the spike proteins. Once the spike protein is produced, it migrates to the outside of the cell to be anchored on the cells’ outer surface, where the immune system will recognize it and develop an immune response to it. (antibodies, T cells, B cells).

Soluble spike proteins

Ideally, the whole spike protein should stay attached to the outside of the cells. Sometimes incomplete spike proteins are produced in the form of spike peptides. As shown below, they are also presented to the immune system by cells outside the surface with an anchoring protein called the Major Histocompatibility Complex (MHC).

Anchoring to the cells is critical because once the spike protein or its pieces in the form of peptides become soluble or float in the bloodstream, they induce inflammation and clot formation in the arteries and capillaries. Scientists have found several ways that it happens.

First is that enzymes called metalloproteinases can cut the MHC1 at their bases.[1] Free-floating MHCs are found in patients with systemic lupus erythematosus SLE and cancers.[4][5]

The second is that errors can happen while RNA splicing occurs inside the nucleus. This results in variant spike proteins that are soluble.[2] Soluble S1 subunits were observed among recipients of the Moderna shots.[3

You can read more about it in this article: SARS-CoV-2 spike proteins detected in the plasma following Moderna shots.

Third, are exosomes released from cells containing MHCs with the spike proteins. [6] T-cells can interact with the spike proteins in the exosomes and cause inflammation [7]. Immunogenic spike proteins inside exosomes were demonstrated after Pfizer injection[8].

 Donor Blood Can Have Spike Protein Exosomes

The normal blood vessel

All organs in the body need an adequate blood supply, and blood vessels have to be in pristine working conditions for that to happen. They should be distensible to allow greater blood flow during exertion, smooth inside to prevent blood clot formation, and have working mechanisms to repair themselves and dissolve blood clots that may form.

All that work falls on the endothelial cells that line the inner wall of the blood vessels, andI talked about them at The Magical Endothelium. Any injury to the endothelium can elicit an inflammatory response and clot formation leading to organ dysfunctions like heart attacks, strokes, and deaths. 

Blood clots always start small, and once they develop, they initiate a chain reaction that promotes a more extensive clot. The good thing is that the body can do fibrinolysis, a built-in mechanism to dissolve clots.

13 ways Spike Proteins cause disease

The following are how the spike proteins and their S1 subunit can cause damage. They can work together and have four results, inflammationthrombosis or clot formation, auto-immunity, and amyloid formation.

Any foreign protein inside the body can elicit inflammation. That is why parts of the spike proteins in the form of their S1 subunits or shorter fragments are enough to cause damage.[9][10].

Inflammation and thrombosis

The S1 subunit activates Toll-like receptor 4 (TLR4) signaling to induce pro-inflammatory responses. It happens with the spike protein in COVID-19 [10] and the S1 subunits.[12]

The spike protein triggers cell signaling events that promote pulmonary vascular remodeling and pulmonary arterial hypertension (PAH), and other cardiovascular complications [13]Source: Suzuki and Gychka. Vaccines 2

The spike S1 initiates inflammatory responses from tumor-necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6) to initiate a cytokine storm syndrome in the lungs. [14].

Spike proteins cause vascular leaks by degrading the barrier of the endothelium. [15] The leak may explain the proliferation of lymphocytes seen by German pathologists in the organs of deceased patients who died after the shots.

Spike proteins affect the cardiac pericytes, the cells that “supervise” the endothelial cells responsible for maintaining the smoothness of the blood vessels. [16]. Study shows spike proteins affect cardiac pericytes and explain why soccer players collapse

Spike proteins downregulate the ACE2 and impair endothelial function [17]

The S1 produces blood clots resistant to the body’s fibrinolysis and hospital clot-buster medications [18]. That’s why some have their limbs amputated after the shots. One woman had both legs and hands amputated. There’s a list here.

The spike protein can cause inflammation by activating the alternate complement pathway. [20]

Long COVID-Syndrome

  1. The S1 Proteins can persist in CD16+ Monocytes up to 15 Months Post-Infection and vaccination to induce chronic inflammation. This explains the symptoms of the Long COVID Syndrome. [19]

Amyloids formation and interaction

  1. Amyloids are fibrillar proteins. They are most commonly associated with neurodegenerative diseases like dementia. However, they can also form in the heart and lungs and make them rigid and form blood clots resistant to dissolution. [21The SARS-CoV-2 spike protein can form amyloids seen in lung, blood, and nervous system disorders
  2. The S1 protein contains heparin-binding sites that attract amyloids to initiate amyloid protein aggregation. Amyloid formation leads to neurodegeneration like Parkinson’s Disease, Alzheimer’s’ disease, and Frontal lobe dementia. [22]

Molecular mimicry

12. Molecular mimicry happens if protein sequences in the spike protein and peptides have similarities to human proteins. Antibodies made for those viral proteins may also attack the host proteins.[24][25][26].

This leads to several autoimmune diseases like immune thrombocytopenia (low platelet counts) [23], autoimmune liver diseasesGuillain-Barré syndromeIgA nephropathyrheumatoid arthritis, and systemic lupus erythematosus[27]

Cancer and Immune Deficiency

  1. Spike proteins impair DNA damage repair and result in ineffective antibodies and damaged tumor-suppressor genes like the BRCA1 and 53BP1 that lead to cancers. BRCA1 damage is associated with breast, ovarian, and prostate cancers.

53BP1 loss of function in tumor tissues is elated to tumor occurrence, progression, and poor prognosis in human malignancies.[30]

Parting thoughts

The disease-causing part of the SARS-CoV-2 virus is the spike protein, and it is present in COVID-19 and the COVID injections. Prevention and early treatment are possible for COVID-19. Once you have the shot, there is no way to control the spike protein.

It is unclear why not all have the adverse effects or die. What is sure is that there are over one million reported adverse effects on VAERS, and more than one hundred thousand have been killed. Vaccine-induced deaths in the U.S. and Europe are way higher than the VAERS reports!

This list is not all-inclusive, and I probably missed some. Indeed, more will be discovered in the future, and I don’t want my body to find out. Do you?

Don’t Get Sick!

Knowledge about Covid-19 is rapidly evolving. Stay current by subscribing. Feel free to share and like.

If you find value in the articles, please consider donating to show your support.

Related:

  1. Blood Vessel Damaging Proteins of the SARS-CoV-2
  2. Cerebral Thrombosis after the Pfizer Covid-19 Vaccine
  3. The High Risk of Deadly Brain Clots in the J & J COVID Vaccine
  4. This Study shows a Ten-Fold Risk of Developing Blood Clots after the COVID Vaccines.
  5. You got the COVID shot and found that others developed blood clots. Now what?
  6. Platelet Changes Causes Blood Clots in COVID-19
  7. Unidentified Foreign Bodies in the Vaccines Form Clots
  8. Retinal complications after COVID shots
  9. U.K. Study of COVID-19 shots and Excess Rates of Guillain-Barré Syndrome
  10. mRNA Vaccination Increases the Risk of Acute Coronary Syndrome
  11. German Analysis: The Higher the Vaccination Rate, the Higher the Excess Mortality
  12. Anti-Idiotype Antibodies against the Spike Proteins may Explain Myocarditis

References:

  1. Rijkers GT, Weterings N, Obregon-Henao A, et al. Antigen Presentation of mRNA-Based and Virus-Vectored SARS-CoV-2 VaccinesVaccines (Basel). 2021;9(8):848. Published 2021 Aug 3. doi:10.3390/vaccines9080848
  2. Kowarz E, Krutzke L, Reis J, et al. “Vaccine-Induced Covid-19 Mimicry” Syndrome: Splice reactions within the SARS-CoV-2 Spike open reading frame result in Spike protein variants that may cause thromboembolic events in patients immunized with vector-based vaccines. Research Square; 2021. DOI: 10.21203/rs.3.rs-558954/v1
  3. Ogata AF. et al. Circulating SARS-CoV-2 Vaccine Antigen Detected in the Plasma of mRNA-1273 Vaccine Recipients [published online ahead of print, 2021 May 20]. Clin Infect Dis. 2021;ciab465. doi:10.1093/cid/ciab465
  4. Hervier B, Ribon M, Tarantino N, Mussard J, Breckler M, Vieillard V, Amoura Z, Steinle A, Klein R, Kötter I, Decker P. Increased Concentrations of Circulating Soluble MHC Class I-Related Chain A (sMICA) and sMICB and Modulation of Plasma Membrane MICA Expression: Potential Mechanisms and Correlation With Natural Killer Cell Activity in Systemic Lupus Erythematosus. Front Immunol. 2021 May 3;12:633658. doi: 10.3389/fimmu.2021.633658. PMID: 34012432; PMCID: PMC8126610.
  5. Salih, Helmut & Goehlsdorf, Dennis & Steinle, Alexander. (2006). Salih HR, Goehlsdorf D, Steinle A. Release of MICB molecules by tumor cells: mechanism and soluble MICB in sera of cancer patients. Hum Immunol 67: 188-195. Human immunology. 67. 188-95. 10.1016/j.humimm.2006.02.008.
  6. Edgar JR. Q&A: What are exosomes, exactly?BMC Biol. 2016;14:46. Published 2016 Jun 13. doi:10.1186/s12915-016-0268-z
  7. Raposo G, Nijman HW, Stoorvogel W, Liejendekker R, Harding CV, Melief CJ, Geuze HJ. B lymphocytes secrete antigen-presenting vesicles. J Exp Med. 1996 Mar 1;183(3):1161-72. doi: 10.1084/jem.183.3.1161. PMID: 8642258; PMCID: PMC2192324.
  8. Bansal et al. Cutting Edge: Circulating Exosomes with COVID Spike Protein Are Induced by BNT162b2 (Pfizer–BioNTech) Vaccination prior to Development of Antibodies: A Novel Mechanism for Immune Activation by mRNA Vaccines. J Immunol November 15, 2021, 207 (10) 2405-2410
  9. Nuovo, G.J. et al. (2021) Endothelial cell damage is the central part of COVID-19 and a mouse model induced by injection of the S1 subunit of the spike protein. Ann. Diagn. Pathol. 51, 151682, https://doi.org/10.1016/j.anndiagpath.2020.151682
  10. Gu, T. et al. (2020) Cytokine signature induced by SARS-CoV-2 spike protein in a mouse model. Front. Immunol. 11, 621441,
  11. Aboudounya MM, Heads RJ. COVID-19 and Toll-Like Receptor 4 (TLR4): SARS-CoV-2 May Bind and Activate TLR4 to Increase ACE2 Expression, Facilitating Entry and Causing Hyperinflammation. Mediators Inflamm. 2021 Jan 14;2021:8874339. doi: 10.1155/2021/8874339. PMID: 33505220; PMCID: PMC7811571.
  12. Shirato K, Kizaki T. SARS-CoV-2 spike protein S1 subunit induces pro-inflammatory responses via toll-like receptor 4 signaling in murine and human macrophages. Heliyon. 2021 Feb 2;7(2):e06187. doi: 10.1016/j.heliyon.2021.e06187. PMID: 33644468; PMCID: PMC7887388. https://pubmed.ncbi.nlm.nih.gov/33644468/
  13. Suzuki YJ, et al. SARS-CoV-2 Spike Protein Elicits Cell Signaling in Human Host Cells: Implications for Possible Consequences of COVID-19 VaccinesVaccines (Basel). 2021;9(1):36. Published 2021 Jan 11. doi:10.3390/vaccines9010036
  14. Cao, X. et al. (2021) Spike protein of SARS-CoV-2 activates macrophages and contributes to induction of acute lung inflammation in male mice. FASEB J. 35, e21801
  15. Biering et al. SARS-CoV-2 Spike triggers barrier dysfunction and vascular leak via integrins and TGF-β signaling. bioRxiv 2021.12.10.472112
  16. Avolio E et al.  The SARS-CoV-2 Spike protein disrupts human cardiac pericytes function through CD147 receptor-mediated signaling: a potential non-infective mechanism of COVID-19 microvascular disease. Clin Sci (Lond). 2021 Dec 22;135(24):2667-2689. doi: 10.1042/CS20210735. PMID: 34807265; PMCID: PMC8674568.
  17. Lei, Y. et al. SARS-CoV-2 Spike Protein Impairs Endothelial Function via Downregulation of ACE 2. Circulation Research. 2021;128:1323–1326
  18. Grobbelaar, L.M. et al. (2021) SARS-CoV-2 spike protein S1 induces fibrin(ogen) resistant to fibrinolysis: implications for microclot formation in COVID-19. Biosci. Rep. 41 (8)
  19. Patterson B. et al. Persistence of SARS CoV-2 S1 Protein in CD16+ Monocytes in Post-Acute Sequelae of COVID-19 (PASC) Up to 15 Months Post-Infection.bioRxiv 2021.06.25.449905
  20. Yu J, Yuan X, Chen H, Chaturvedi S, Braunstein EM, Brodsky RA. Direct activation of the alternative complement pathway by SARS-CoV-2 spike proteins is blocked by factor D inhibition. Blood. 2020.
  21. Nyström et al. Amyloidogenesis of SARS-CoV-2 Spike Protein. bioRxiv 2021.12.16.472920. 
  22. Idrees D, Kumar V. SARS-CoV-2 spike protein interactions with amyloidogenic proteins: Potential clues to neurodegeneration. Biochem Biophys Res Commun. 2021 May 21;554:94-98. doi: 10.1016/j.bbrc.2021.03.100. Epub 2021 Mar 24. PMID: 33789211; PMCID: PMC7988450
  23. Nunez-Castilla, J et al. Spike mimicry of thrombopoietin may induce thrombocytopenia in COVID-19. bioRxiv 2021.08.10.455737
  24. Ehrenfeld M et al. Covid-19 and autoimmunity. Autoimmun Rev. 2020;19:102597.
  25. Kanduc D, Shoenfeld Y. On the molecular determinants of the SARS-CoV-2 attack. Clin Immunol. 2020;215. 
  26. Vojdani A, Kharrazian D. Potential antigenic cross-reactivity between SARS-CoV-2 and human tissue with a possible link to an increase in autoimmune diseases. Clin Immunol. 2020;217:108480
  27. Chen Y, Xu Z, Wang P, Li XM, Shuai ZW, Ye DQ, Pan HF. New-onset autoimmune phenomena post-COVID-19 vaccination. Immunology. 2021 Dec 27. doi: 10.1111/imm.13443. Epub ahead of print. PMID: 34957554.
  28. Jiang H, Mei YF. SARS-CoV-2 Spike Impairs DNA Damage Repair and Inhibits V(D)J Recombination In VitroViruses. 2021;13(10):2056. Published 2021 Oct 13. doi:10.3390/v13102056
  29. BRCA1 gene. Medline [website]
  30. Mirza-Aghazadeh-Attari M, et al.  53BP1: A key player of DNA damage response with critical functions in cancer. DNA Repair (Amst). 2019 Jan;73:110-119. doi: 10.1016/j.dnarep.2018.11.008. Epub 2018 Nov 20. PMID: 30497961.

© 2018 – 2022 Asclepiades Medicine, L.L.C. All Rights Reserved
DrJesseSantiano.com does not provide medical advice, diagnosis, or treatment

NIH study uncovers blood vessel damage and inflammation in COVID-19 patients’ brains but no infection

Authors: Christopher G. Thomas, 301-496-5751, nindspressteam@ninds.nih.gov

Results from a study of 19 deceased patients suggests brain damage is a byproduct of a patient’s illness.

In an in-depth study of how COVID-19 affects a patient’s brain, National Institutes of Health researchers consistently spotted hallmarks of damage caused by thinning and leaky brain blood vessels in tissue samples from patients who died shortly after contracting the disease. In addition, they saw no signs of SARS-CoV-2 in the tissue samples, suggesting the damage was not caused by a direct viral attack on the brain. The results were published as a correspondence in the New England Journal of Medicine.

“We found that the brains of patients who contract infection from SARS-CoV-2 may be susceptible to microvascular blood vessel damage. Our results suggest that this may be caused by the body’s inflammatory response to the virus,” said Avindra Nath, M.D., clinical director at the NIH’s National Institute of Neurological Disorders and Stroke (NINDS) and the senior author of the study. “We hope these results will help doctors understand the full spectrum of problems patients may suffer so that we can come up with better treatments.”

For More Information: https://www.nia.nih.gov/news/nih-study-uncovers-blood-vessel-damage-and-inflammation-covid-19-patients-brains-no-infection

Direct activation of the alternative complement pathway by SARS-CoV-2 spike proteins is blocked by factor D inhibition

Authors: Jia YuXuan YuanHang ChenShruti ChaturvediEvan M. BraunsteinRobert A. Brodsky

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a highly contagious respiratory virus that can lead to venous/arterial thrombosis, stroke, renal failure, myocardial infarction, thrombocytopenia, and other end-organ damage. Animal models demonstrating end-organ protection in C3-deficient mice and evidence of complement activation in humans have led to the hypothesis that SARS-CoV-2 triggers complement-mediated endothelial damage, but the mechanism is unclear. Here, we demonstrate that the SARS-CoV-2 spike protein (subunit 1 and 2), but not the N protein, directly activates the alternative pathway of complement (APC). Complement-dependent killing using the modified Ham test is blocked by either C5 or factor D inhibition. C3 fragments and C5b-9 are deposited on TF1PIGAnull target cells, and complement factor Bb is increased in the supernatant from spike protein–treated cells. C5 inhibition prevents the accumulation of C5b-9 on cells, but not C3c; however, factor D inhibition prevents both C3c and C5b-9 accumulation. Addition of factor H mitigates the complement attack. In conclusion, SARS-CoV-2 spike proteins convert nonactivator surfaces to activator surfaces by preventing the inactivation of the cell-surface APC convertase. APC activation may explain many of the clinical manifestations (microangiopathy, thrombocytopenia, renal injury, and thrombophilia) of COVID-19 that are also observed in other complement-driven diseases such as atypical hemolytic uremic syndrome and catastrophic antiphospholipid antibody syndrome. C5 inhibition prevents accumulation of C5b-9 in vitro but does not prevent upstream complement activation in response to SARS-CoV-2 spike proteins.

For More Information: https://ashpublications.org/blood/article/136/18/2080/463611/Direct-activation-of-the-alternative-complement

SARS-CoV-2 spike protein-mediated cell signaling in lung vascular cells

Authors: Yuichiro J. Suzuki,a,⁎ Sofia I. Nikolaienko,b Vyacheslav A. Dibrova,b Yulia V. Dibrova,b Volodymyr M. Vasylyk,c Mykhailo Y. Novikov,d Nataliia V. Shults,a and Sergiy G. Gychkab

Currently, the world is suffering from the pandemic of coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that uses angiotensin-converting enzyme 2 (ACE2) as a receptor to enter the host cells. So far, 60 million people have been infected with SARS-CoV-2, and 1.4 million people have died because of COVID-19 worldwide, causing serious health, economical, and sociological problems. However, the mechanism of the effect of SARS-CoV-2 on human host cells has not been defined. The present study reports that the SARS-CoV-2 spike protein alone without the rest of the viral components is sufficient to elicit cell signaling in lung vascular cells. The treatment of human pulmonary artery smooth muscle cells or human pulmonary artery endothelial cells with recombinant SARS-CoV-2 spike protein S1 subunit (Val16 – Gln690) at 10 ng/ml (0.13 nM) caused an activation of MEK phosphorylation. The activation kinetics was transient with a peak at 10 min. The recombinant protein that contains only the ACE2 receptor-binding domain of the SARS-CoV-2 spike protein S1 subunit (Arg319 – Phe541), on the other hand, did not cause this activation. Consistent with the activation of cell growth signaling in lung vascular cells by the SARS-CoV-2 spike protein, pulmonary vascular walls were found to be thickened in COVID-19 patients. Thus, SARS-CoV-2 spike protein-mediated cell growth signaling may participate in adverse cardiovascular/pulmonary outcomes, and this mechanism may provide new therapeutic targets to combat COVID-19.

Dr. Charles Hoffe issues Vaccine warning… Deep dive on endothelial damage to blood vessels…

Author: Dr. Charles Hoffe

in a Coronavirus, that spike protein becomes part of the viral capsule. In other words, the cell wall around the virus, called the viral capsule. But it’s not in the virus. It’s in your cells. So it therefore becomes part of the cell wall of your vascular endothelium. Which means that these cells that line your blood vessels, which are supposed to be smooth so that blood flows smoothly, now have these little spikey bits sticking out.

So it is absolutely inevitable that blood clots will form. Because your blood platelets circulate around in your blood vessels. And the purpose of blood platelets is to detect a damaged vessel and block that vessel to stop bleeding. So when the platelet comes through the capillary, it suddenly hits all these all these Covid spikes that are jutting into the inside of the vessel, it is absolutely inevitable that a blood clot will form to block that vessel. That’s how platelets work.

For More Information: https://citizenfreepress.com/breaking/dr-charles-hoffe-issues-vaccine-warning/

What Is the D-Dimer Test?

Authors: Richard N. Fogoros, MD

The D-dimer test is a blood test that indicates whether blood clots are being actively formed somewhere within a person’s vascular system. This test is most often helpful in the diagnosis of pulmonary embolus and deep vein thrombosis, but it can also be useful in diagnosing other medical conditions in which blood clots play a role.

However, there are limitations to the D-dimer test, and it can be tricky to evaluate the results. In order to avoid being misled by it, doctors need to make sure they are using this test at the appropriate times and must take due care in interpreting the results.

For More Information: https://www.verywellhealth.com/d-dimer-test-4173338