COVID-19 also attacks the pancreas; one vaccine dose may be enough for those previously infected

Authors: Nancy Lapid February 3, 2021

COVID-19 attacks the pancreas

The new coronavirus directly targets the pancreas, infecting and damaging its insulin producing cells, according to a new study. The findings may help explain why blood sugar problems develop in many COVID-19 patients, and why there have been reports of diabetes developing as a result of the virus. The pancreas has two jobs: production of enzymes important to digestion, and creation and release of the hormones insulin and glucagon that regulate blood sugar levels. In a paper published on Wednesday in Nature Metabolism, researchers report that lab and autopsy studies show the new coronavirus infects pancreas cells involved in these processes and changes their shape, disturbs their genes, and impairs their function. The new data “identify the human pancreas as a target of SARS-CoV-2 infection and suggest that beta-cell infection could contribute to the metabolic dysregulation observed in patients with COVID-19,” the authors conclude. (https://go.nature.com/36Cmtfy)

One vaccine dose might be enough for COVID-19 survivors

COVID-19 survivors might only need one shot of the new vaccines from Moderna Inc and Pfizer/BioNTech, instead of the usual two doses, because their immune systems have gotten a head start on learning to recognize the virus, according to two separate reports posted this week on medRxiv ahead of peer review. In one study of 59 healthcare workers who recovered from COVID-19 and received one of the vaccines, antibody levels after the first shot were higher than levels usually seen after two doses in people without a history of COVID-19. In a separate study, researchers found that 41 COVID-19 survivors developed “high antibody titers within days of vaccination,” and those levels were 10 to 20 times higher than in uninfected, unvaccinated volunteers after just one vaccine dose. “The antibody response to the first vaccine dose in individuals with pre-existing immunity is equal to or even exceeds” levels found in uninfected individuals after the second vaccine dose, the authors of that paper said. “Changing the policy to give these individuals only one dose of vaccine would not negatively impact on their antibody titers, spare them from unnecessary pain and free up many urgently needed vaccine doses,” they said. (https://bit.ly/3je4Zv4; https://bit.ly/2YG0EYf)

Gout drug shows promise for mildly ill COVID-19 patients

Colchicine, an anti-inflammatory drug used to treat gout and other rheumatic diseases, reduced hospitalizations and deaths by more than 20% in COVID-19 patients in a large international trial. COVID-19 patients with mild illness and at least one condition that put them at high risk for complications, such as diabetes or heart disease, received either colchicine or a placebo for 30 days. Overall, the risk of hospitalization or death was statistically similar in the two groups. But among the 4,159 patients whose coronavirus infections had been diagnosed with a gold-standard PCR test, death or hospital admission occurred in 4.6% of those on colchicine versus 60% of those who got a placebo. After taking patients’ other risk factors into account, colchicine was associated with a statistically significant 25% risk reduction, the researchers reported on medRxiv ahead of peer review. Patients taking colchicine also had fewer cases of pneumonia. “Given that colchicine is inexpensive, taken by mouth, was generally safe in this study, and does not generally need lab monitoring during use, it shows potential as the first oral drug to treat COVID-19 in the outpatient setting,” the researchers said. (https://bit.ly/3oDSDgY)

Oxford/AstraZeneca vaccine might work better with doses months apart

Among recipients of the COVID-19 vaccine from Oxford University and AstraZeneca, prolonging the interval between the first and second doses led to better results, researchers said in a paper posted on Monday ahead of peer-review by The Lancet on its preprint site. For volunteers aged 18 to 55, vaccine efficacy was 82.4% with 12 or more weeks between doses, compared to 54.9% when the booster was given within 6 weeks after the first dose. The longest interval between doses given to older volunteers was 8 weeks, so there were no data for the efficacy of a 12-week dosing gap in that group. Europe’s medicine regulator has said there is not enough data to determine how well the vaccine will work in people over 55. Given their findings, the authors say “a second dose given after a three-month period is an effective strategy … and may be the optimal for rollout of a pandemic vaccine when supplies are limited in the short term.”

Inflammasome activation at the crux of severe COVID-19

Authors: Setu M. Vora,1,2Judy Lieberman,2,3 and Hao Wu1,2

Abstract

The COVID-19 pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), results in life-threatening disease in a minority of patients, especially elderly people and those with co-morbidities such as obesity and diabetes. Severe disease is characterized by dysregulated cytokine release, pneumonia and acute lung injury, which can rapidly progress to acute respiratory distress syndrome, disseminated intravascular coagulation, multisystem failure and death. However, a mechanistic understanding of COVID-19 progression remains unclear. Here we review evidence that SARS-CoV-2 directly or indirectly activates inflammasomes, which are large multiprotein assemblies that are broadly responsive to pathogen-associated and stress-associated cellular insults, leading to secretion of the pleiotropic IL-1 family cytokines (IL-1β and IL-18), and pyroptosis, an inflammatory form of cell death. We further discuss potential mechanisms of inflammasome activation and clinical efforts currently under way to suppress inflammation to prevent or ameliorate severe COVID-19.

Introduction

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus responsible for COVID-19, has so far infected more than 190 million people and caused death of more than 4.1 million people worldwide. The virus primarily infects the respiratory tract, causing fever, sore throat, anosmia and dyspnoea, but its tissue tropism still remains to be fully understood. As many as 10–15% of patients develop severe pneumonia, with some cases progressing to hypoxia and acute respiratory distress syndrome (ARDS), which requires mechanical ventilation in a critical care setting and has high mortality. Patients can also develop multi-organ failure, acute kidney injury and disseminated intravascular coagulation, among a host of other disorders111. Aside from supportive care, only a few treatments have been approved for COVID-19, and their reduction of mortality has been limited1214. Although several vaccines against SARS-CoV-2 have been approved and are being administered internationally, there will still be a significant number of infections owing to people who are not vaccinated in regions with inadequate access or acceptance of vaccination. In addition, while global vaccination efforts strive to meet the challenge of ending the pandemic, the appearance of immune-evasive viral variants and the unlikelihood of reaching immediate herd immunity underscore the continued need for additional treatments mitigating disease progression1519.

Most researchers agree that an inappropriate hyperinflammatory response lies at the root of many severe cases of COVID-19, driven by overexuberant inflammatory cytokine release. Consistently, co-morbidities, such as obesity, diabetes, heart disease, hypertension and ageing, which are prognostic of poor outcome, are associated with high basal inflammation7,11,20,21. It has been proposed since the beginning of the pandemic that these co-morbidities and the ensuing hyperinflammatory response may be aetiologically linked through overactive inflammasome signaling, which may account for the association of these co-morbidities with severe COVID-19 in the context of chronic inflammation as well as for COVID-19 progression in the context of a robust acute inflammatory response to infection2229. However, many of the studies that seek to understand the immune response to SARS-CoV-2 are based on RNA sequencing, often of thawed cells, and infected, activated or dying cells do not survive freeze–thaw well, which could skew results. Moreover, inflammasome activation does not directly induce transcriptional responses, and its detection is less straightforward than that of most other signaling pathways. Nonetheless, several studies are now accumulating that support direct (infection-induced) and indirect inflammasome activation and the critical role of inflammasomes in severe COVID-19. Here we discuss the available evidence, potential mechanisms and the implications for therapy.

Key to inflammation and innate immunity, are large, micrometer-scale multiprotein cytosolic complexes that assemble in response to pathogen-associated molecular patterns (PAMPs) or damage-associated molecular patterns (DAMPs) and trigger proinflammatory cytokine release as well as pyroptosis, a proinflammatory lytic cell death30,31 (Fig. 1). Upon activation by PAMPs or DAMPs, canonical inflammasome sensors — mainly in monocytes, macrophages and barrier epithelial cells — oligomerize and recruit the adaptor apoptosis-associated speck-like protein containing a CARD (ASC) to form inflammasome specks, within which the inflammatory caspase 1 is recruited and activated. Inflammasome sensors are activated in response to different triggers and differ in their overall specificities to PAMPs or DAMPs. NLRP3, the most broadly activated inflammasome sensor and a member of the nucleotide-binding domain- and leucine-rich repeat-containing protein (NLR) family, responds to an array of insults to the cell that cause cytosolic K+ efflux, Ca2+ cytosolic influx or release of mitochondrial reactive oxygen species (ROS)31,32. These insults include extracellular ATP, membrane permeabilization by pore-forming toxins and large extracellular aggregates such as uric acid crystals, cholesterol crystals and amyloids30. Other sensors, such as AIM2 and NLRC4, are tuned to recognize specific PAMPs and DAMPs, such as cytosolic double-stranded DNA and bacterial proteins, respectively31. In a parallel pathway, the mouse inflammatory caspase 11 and human caspase 4 and caspase 5 sense PAMPs and DAMPs such as bacterial lipopolysaccharide (LPS) that gain cytosolic access and endogenous oxidized phospholipids, leading directly to membrane damage or pyroptosis, and secondary K+ efflux followed by noncanonical NLRP3 inflammasome activation3336.

For More Information: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8351223/