[Renin-Angiotensin-System (RAS) and COVID-19 - On The Prescription of RAS Blockers]

Neuropilin Is a New Player in the Pathogenesis of COVID-19

Abstract—A family of glycoproteins called neuropilins is gaining attention as a new contributor to the pathogenesis of COVID-19. The concept of penetration of SARS-CoV-2 into host cells is traditionally associated with the receptor role of the ACE2 protein. New evidence suggests that it is possible to enhance pulmonary viral infection by involvement of neuropilins. Neuropilins have two prominent features: (a) a wide range of participation in cellular and tissue processes; (b) a concomitant enhancement of effects associated with the co-reception of regulatory proteins. These features determine the special role of functionally disseminated neuropilins in the pathogenesis of vascular system damage, immunothrombosis, and organ damage with comorbid manifestations during COVID-19. However, the presentation of neuropilins as a generalized therapeutic target that has a corrective effect on the affected areas is an ambiguous approach and requires a selective strategy.

Damage to the Vascular Endothelium as a Leading Mechanism of COVID-19 Systemic Pathology

An analysis of the molecular and pathophysiological mechanisms of COVID-19 is presented. The endothelium of blood vessels, a kind of “endocrine tree” of the lungs and other organs in which important pathophysiological processes are concentrated, is considered as the target of the aggressive effects of the SARS-CoV-2 coronavirus. Since the main cellular target of viral aggression is the ACE2 enzyme, consideration of its role is the main line of discussion. Coronavirus blocks the activity of ACE2, a natural producer of angiotensins peptides, thus disrupting the balance of hemovascular control. Under normal conditions this mission is performed by the ACE/ACE2 complex, enzymes that control the synthesis and physiological activity of angiotensins and bradykinin peptides. Changes in the ACE/ACE2 axis ratios and cytokine stress are associated with endothelial dysfunction and a number of vascular disorders. The STORM-2 concept is proposed for the first time. According to the concept, the cause of severe organ pathology is the violation of hemostasis, transcellular diffusion, and maintenance of blood pressure.

Indomethacin: Can It Counteract Bradykinin Effects in COVID-19 Patients?

COVID-19 represents the biggest health challenge. Although the mortality rate of COVID-19 is low, the high numbers of infected people and those with post-COVID-19 symptoms represent a real problem for the health system. A high number of patients with COVID-19 or people recovered from COVID-19 suffer from a dry cough and/or myalgia. Interestingly, an imbalance in bradykinin was observed in COVID-19 patients, which might be due to the accumulation of bradykinin as a result of a reduction in the degradation of bradykinin. This finding inspired the idea of possible similitude between the dry cough that is induced by angiotensin-converting enzyme inhibitors and the COVID-19-induced dry cough. Both of these types of cough are mediated, at least partially, by bradykinin. They both manifested as a persistent dry cough that is not responded to traditional dry cough remedies. However, several drugs were previously investigated for the treatment of angiotensin-converting enzyme inhibitor–induced dry cough. Here, we hypothesized that such treatment might be useful in COVID-19-induced dry cough and other bradykinin-related symptoms such as generalized pain and myalgia. In this article, evidence was presented to support the use of indomethacin as a potential treatment of COVID-19-induced dry cough. The choice of indomethacin was based on its ability to suppress the cyclooxygenase enzyme while also lowering the level of the inflammatory mediator bradykinin. Furthermore, indomethacin has been shown to be effective in treating angiotensin-converting enzyme inhibitor–induced dry cough. Moreover, indomethacin is a long-established, low-cost, effective, and readily available medication.

Flavonoids as potential therapeutics against novel coronavirus disease-2019 (nCOVID-19)

Since time immemorial natural products have been a great source of medicine to mankind. The anti-viral activities from several ayurvedic herbal medicines (in the form of crude extract or fraction or isolated compounds) have been established but their effectiveness against coronavirus still needs to be explored. They can provide a rich resource of anti-SARS-CoV-2 drug candidates. In this paper, in-silico techniques have been used to identify the potential lead molecules against SARS-CoV-2. A list of flavonoids having anti-viral activity was prepared and evaluated against the selected target. Rhoifolin, 5,7-dimethoxyflavanone-4'-O-β-d-glucopyranoside, baicalin, astragalin, luteolin, and kaempferol showed good binding affinity and thus these could be promising compounds. In-silico screening such as ADMET prediction has been performed which predicted that the selected flavonoids have good pharmacokinetics and pharmacodynamics properties. Molecular dynamics simulation studies and MM-PBSA binding free energy calculations showed luteolin to be a more effective candidate against viral protein Mpro. The novelty of the approach mainly rests in the identification of potent anti-viral natural molecules from natural products flavonoid group of molecules to be effective against the latest coronavirus infection.Communicated by Ramaswamy H. Sarma.

Hemostatic abnormalities in COVID-19: A guided review

The spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has already taken on pandemic proportions, affecting over 213 countries in a matter of weeks. In this context, several studies correlating hemostatic disorders with the infection dynamics of the new coronavirus have emerged. These studies have shown that a portion of the patients affected by Coronavirus Disease 2019 (COVID-19) have prolonged prothrombin time (PT) and activated partial thromboplastin time (APTT), elevated D-dimer levels and other fibrinolytic products, antithrombin (AT) activity reduced and decrease of platelet count. Based on these hallmarks, this review proposes to present possible pathophysiological mechanisms involved in the hemostatic changes observed in the pathological progression of COVID-19. In this analysis, it is pointed the relationship between the downregulation of angiotensin-converting enzyme 2 (ACE2) and storm cytokines action with the onset of hypercoagulability state, other than the clinical events involved in thrombocytopenia and hyperfibrinolysis progression.