Identifying pathophysiological bases of disease in COVID-19

ADAM-17 Activity and Its Relation to ACE2: Implications for Severe COVID-19

There is a lack of studies aiming to assess cellular a disintegrin and metalloproteinase-17 (ADAM-17) activity in COVID-19 patients and the eventual associations with the shedding of membrane-bound angiotensin-converting enzyme 2 (mACE2). In addition, studies that investigate the relationship between ACE2 and ADAM-17 gene expressions in organs infected by SARS-CoV-2 are lacking. We used data from the Massachusetts general hospital COVID-19 study (306 COVID-19 patients and 78 symptomatic controls) to investigate the association between plasma levels of 33 different ADAM-17 substrates and COVID-19 severity and mortality. As a surrogate of cellular ADAM-17 activity, an ADAM-17 substrate score was calculated. The associations between soluble ACE2 (sACE2) and the ADAM-17 substrate score, renin, key inflammatory markers, and lung injury markers were investigated. Furthermore, we used data from the Genotype-Tissue Expression (GTEx) database to evaluate ADAM-17 and ACE2 gene expressions by age and sex in ages between 20-80 years. We found that increased ADAM-17 activity, as estimated by the ADAM-17 substrates score, was associated with COVID-19 severity (p = 0.001). ADAM-17 activity was also associated with increased mortality but did not reach statistical significance (p = 0.06). Soluble ACE2 showed the strongest positive correlation with the ADAM-17 substrate score, follow by renin, interleukin-6, and lung injury biomarkers. The ratio of ADAM-17 to ACE2 gene expression was highest in the lung. This study indicates that increased ADAM-17 activity is associated with severe COVID-19. Our findings also indicate that there may a bidirectional relationship between membrane-bound ACE2 shedding via increased ADAM-17 activity, dysregulated renin-angiotensin system (RAS) and immune signaling. Additionally, differences in ACE2 and ADAM-17 gene expressions between different tissues may be of importance in explaining why the lung is the organ most severely affected by COVID-19, but this requires further evaluation in prospective studies.

Therapeutic Approaches in COVID-19 Patients: The Role of the Renin-Angiotensin System

Two and a half years after COVID-19 was first reported in China, thousands of people are still dying from the disease every day around the world. The condition is forcing physicians to adopt new treatment strategies while emphasizing continuation of vaccination programs. The renin-angiotensin system plays an important role in the development and progression of COVID-19 patients. Nonetheless, administration of recombinant angiotensin-converting enzyme 2 has been proposed for the treatment of the disease. The catalytic activity of cellular ACE2 (cACE2) and soluble ACE2 (sACE2) prevents angiotensin II and Des-Arg-bradykinin from accumulating in the body. On the other hand, SARS-CoV-2 mainly enters cells via cACE2. Thus, inhibition of ACE2 can prevent viral entry and reduce viral replication in host cells. The benefits of bradykinin inhibitors (BKs) have been reported in some COVID-19 clinical trials. Furthermore, the effects of cyclooxygenase (COX) inhibitors on ACE2 cleavage and prevention of viral entry into host cells have been reported in COVID-19 patients. However, the administration of COX inhibitors can reduce innate immune responses and have the opposite effect. A few studies suggest benefits of low-dose radiation therapy (LDR) in treating acute respiratory distress syndrome in COVID-19 patients. Nonetheless, radiation therapy can stimulate inflammatory pathways, resulting in adverse effects on lung injury in these patients. Overall, progress is being made in treating COVID-19 patients, but questions remain about which drugs will work and when. This review summarizes studies on the effects of a recombinant ACE2, BK and COX inhibitor, and LDR in patients with COVID-19.

Predictors of mortality in COVID-19 patients treated with convalescent plasma therapy

Several options to treat hospitalized severe COVID-19 patients have been suggested. The study aimed to describe survival in patients treated with convalescent COVID plasma (CCP) and to identify in-hospital mortality predictors. This prospective cohort study examined data from 112 severe COVID-19 patients hospitalized in the Corona Departments in an acute care hospital who received two units of CCP (at least one of them high-titer). Demographic and medical data was retrieved from the patients’ electronic health records (EHR). Possible predictors for in-hospital mortality were analyzed in a univariate analysis and those found to be clinically significant were further analyzed in a multivariable analysis. Median age was 67 years (IQR 55–74) and 66 (58.9%) of them were males. Of them, 20 (17.9%) died in hospital. On multivariable analysis diabetes mellitus (p = 0.004, OR 91.54), mechanical ventilation (p = 0.001, OR 59.07) and lower albumin levels at treatment (p = 0.027, OR 0.74) were significantly associated with increased in-hospital mortality. In our study, in-hospital mortality in patients receiving CCP is similar to that reported for the general population, however certain variables mentioned above were associated with increased in-hospital mortality. In the literature, these variables were also associated with a worse outcome in patients with COVID-19 who did not receive CCP. As evidence points toward a benefit from CCP treatment in immunocompromised patients, we believe the above risk factors can further define COVID-19 patients at increased risk for mortality, enabling the selection of candidates for early treatment in an outpatient setting if possible.

RAGE against the Machine: Can Increasing Our Understanding of RAGE Help Us to Battle SARS-CoV-2 Infection in Pregnancy?

The receptor of advanced glycation end products (RAGE) is a receptor that is thought to be a key driver of inflammation in pregnancy, SARS-CoV-2, and also in the comorbidities that are known to aggravate these afflictions. In addition to this, vulnerable populations are particularly susceptible to the negative health outcomes when these afflictions are experienced in concert. RAGE binds a number of ligands produced by tissue damage and cellular stress, and its activation triggers the proinflammatory transcription factor Nuclear Factor Kappa B (NF-κB), with the subsequent generation of key proinflammatory cytokines. While this is important for fetal membrane weakening, RAGE is also activated at the end of pregnancy in the uterus, placenta, and cervix. The comorbidities of hypertension, cardiovascular disease, diabetes, and obesity are known to lead to poor pregnancy outcomes, and particularly in populations such as Native Hawaiians and Pacific Islanders. They have also been linked to RAGE activation when individuals are infected with SARS-CoV-2. Therefore, we propose that increasing our understanding of this receptor system will help us to understand how these various afflictions converge, how forms of RAGE could be used as a biomarker, and if its manipulation could be used to develop future therapeutic targets to help those at risk.

Mechanistic Insights Into the Immune Pathophysiology of COVID-19; An In-Depth Review

Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2), which causes coronavirus-19 (COVID-19), has caused significant morbidity and mortality globally. In addition to the respiratory manifestations seen in severe cases, multi-organ pathologies also occur, making management a much-debated issue. In addition, the emergence of new variants can potentially render vaccines with a relatively limited utility. Many investigators have attempted to elucidate the precise pathophysiological mechanisms causing COVID-19 respiratory and systemic disease. Spillover of lung-derived cytokines causing a cytokine storm is considered the cause of systemic disease. However, recent studies have provided contradictory evidence, whereby the extent of cytokine storm is insufficient to cause severe illness. These issues are highly relevant, as management approaches considering COVID-19 a classic form of acute respiratory distress syndrome with a cytokine storm could translate to unfounded clinical decisions, detrimental to patient trajectory. Additionally, the precise immune cell signatures that characterize disease of varying severity remain contentious. We provide an up-to-date review on the immune dysregulation caused by COVID-19 and highlight pertinent discussions in the scientific community. The response from the scientific community has been unprecedented regarding the development of highly effective vaccines and cutting-edge research on novel therapies. We hope that this review furthers the conversations held by scientists and informs the aims of future research projects, which will potentially further our understanding of COVID-19 and its immune pathogenesis.

Covid 19 May Limit the Use of Anti-hyperglycemic Agents. Does it Call for the Development of New Anti-hyperglycemic Agents?

Diabetes mellitus has been identified as a major risk factor for developing severe COVID 19 complications. In this review article, the efforts were directed to provide insights and the possible extent to which some diabetic pharmacological interventions may exacerbate COVID 19 or may not be idyllic options for COVID 19 patients. Articles reviewed were identified using the Google scholar database, and search was done using the English language. Anti-hyperglycemic is associated with undesirable effects including episodes of hypoglycemia, diarrhea, lactic acidosis, and increased risks of cardiovascular and hepatic hazards. These undesirable effects associated with the anti-hyperglycemic agents possess a threat of developing severe COVID19 complications Therefore, this calls for more studies to understand the extent of the risks these agents possess in diabetic COVID 19 patients. Almost all the anti-hyperglycemic agents have the potential to worsen COVID 19, despite their class. COVID 19 may limit the options in terms of available anti-hyperglycemic agents which may not heighten the risk of developing severe COVID 19 complications. The research towards the discovery and development of new compounds and also new therapeutic targets for hyperglycemia should be encouraged and welcome.

COVID-19: Zinc and Angiotensin-Converting Enzyme 2 (ACE2) Deficiencies as Determinants of Risk and Severity of Disease: A Narrative Review

A growing body of evidence supports the premise that deficiencies of zinc and angiotensin-converting enzyme 2 (ACE2, a zinc enzyme) determine severity of coronavirus disease 2019 (COVID-19). ACE2 is part of the renin-angiotensin system (RAS) and acts as a feedback control system moderating blood pressure, keeping blood pressure within normal limits. For a virus to infect a person, the virus has to get inside the person's cells. The virus that causes COVID-19 uses ACE2 to get into the cell. Think of this like an invader from outer space attacking your car by getting in through your cruise control; the RAS is like the cruise control of your car. What happens next depends on how robust your cruise control is. If your cruise control is young and healthy perhaps very little happens; your car may slow down or speed up a bit. But if your cruise control is in poor condition the attack might disrupt the entire speed control system; your car may brake suddenly or speed out of control and crash. Feedback control systems (natural or man-made) are designed to keep dynamic systems in control, but under certain situations can drive the system completely out of control. The RAS is composed of two feedback loops: the ACE loop provides amplification, increasing pro-inflammatory cytokines and blood pressure; the ACE2 loop provides fine control and mitigates the vasoconstrictive, pro-inflammatory, and thrombotic actions of the ACE loop. Usually, there is balance, but in the setting of COVID-19, underlying deficiencies of zinc and ACE2 can lead to an imbalance. Exacerbated by the severe downregulation of ACE2 seen with viral entry, a "tipping point" is reached with loss of control of the RAS system resulting in increased angiotensin II (Ang II) causing downstream vasoconstriction, inflammation, and thromboses. These, in turn, lead to complications often seen in "severe COVID-19" such as acute respiratory distress syndrome (ARDS) or cytokine storm, often seen in high-risk patients in the second week of illness. This model suggests that supplemental zinc could replenish zinc in ACE2, stabilize the ACE2 axis, and prevent disruption of the RAS. This would prevent the vasoconstrictive, inflammatory, and thrombotic actions of Ang II, thus preventing the severe COVID-19 complications which cause the high morbidity and mortality seen in high-risk patients with underlying zinc deficiency. Zinc supplements are available, easy to use, and relatively safe. Randomized clinical trials are needed to confirm safety and efficacy of zinc supplementation to decrease severity of and morality from COVID-19 in high-risk patients. Since replenishment of zinc and active ACE2 in patients in whom these are deficient may take weeks, supplementation in high-risk populations prior to COVID infection may be required. Such supplementation should not replace vaccination but may be useful in populations for whom vaccination is not available or for populations exposed to viral variants to which available vaccines have insufficient coverage.

Role of specialized pro-resolving lipid mediators and their receptors in virus infection: a promising therapeutic strategy for SARS-CoV-2 cytokine storm

Unexpected viral infections outbreaks, significantly affect human health, leading to increased mortality and life disruption. Among them is the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) which emerged as a deadly pandemic, calling for intense research efforts on its pathogenicity mechanism and development of therapeutic strategies. In the SARS-CoV-2 cytokine storm, systemic inflammation has been associated with severe illness and mortality. Recent studies have demonstrated special pro-resolving lipids mediators (SPMs) lipoxins, resolvins, maresins, and protectins as potential therapeutic options for abnormal viral-triggered inflammation. Pro-resolving lipids mediators have shown great promise for the treatment of Herpes simplex virus, respiratory syncytial virus, human immunodeficiency virus, and hepatitis C virus. Based on this, studies are being conducted on their therapeutic effects in SARS-CoV-2 infection. In this review, we discussed SPMs and reviewed evidence from recent studies on SPMs as therapeutic options for viral infections, including SARS-CoV2. Based on our analysis of the previous study, we argue that SPMs are a potential treatment for SARS-CoV-2 infection and other viral infections. We expect further research on how SPMs modulate viral-triggered inflammation through G-protein-coupled receptors (GPCRs), and chemical stability and druggability of SPMs.