The Disease-Modifying Role of Taurine and Its Therapeutic Potential in Coronavirus Disease 2019 (COVID-19).

Taurine is an amino sulfonic acid that is implicated in numerous physiological functions, including the regulation of oxidative stress, which plays an important role in coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), together with other pathophysiological processes. The recent finding of decreased serum taurine levels in SARS-CoV-2-infected patients, in tandem with its potential modulatory role in COVID-19 due to its antiviral, antioxidant, anti-inflammatory, and vascular-related effects, provides a rationale for considering taurine as a beneficial supplement in patients suffering from COVID-19. Here, we reviewed the potential disease-modifying effects of taurine and combined these with the current knowledge on COVID-19 to clarify the potential role of taurine in this respiratory disease.

N-Acetylcysteine and Hydrogen Sulfide in Coronavirus Disease 2019.

Significance: Hydrogen sulfide (H2S) is one of the three main gasotransmitters that are endogenously produced in humans and are protective against oxidative stress. Recent findings from studies focusing on coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), shifted our attention to a potentially modulatory role of H2S in this viral respiratory disease. Recent Advances: H2S levels at hospital admission may be of importance since this gasotransmitter has been shown to be protective against lung damage through its antiviral, antioxidant, and anti-inflammatory actions. Furthermore, many COVID-19 cases have been described demonstrating remarkable clinical improvement upon administration of high doses of N-acetylcysteine (NAC). NAC is a renowned pharmacological antioxidant substance acting as a source of cysteine, thereby promoting endogenous glutathione (GSH) biosynthesis as well as generation of sulfane sulfur species when desulfurated to H2S. Critical Issues: Combining H2S physiology and currently available knowledge of COVID-19, H2S is hypothesized to target three main vulnerabilities of SARS-CoV-2: (i) cell entry through interfering with functional host receptors, (ii) viral replication through acting on RNA-dependent RNA polymerase (RdRp), and (iii) the escalation of inflammation to a potentially lethal hyperinflammatory cytokine storm (toll-like receptor 4 [TLR4] pathway and NLR family pyrin domain containing 3 [NLRP3] inflammasome). Future Directions: Dissecting the breakdown of NAC reveals the possibility of increasing endogenous H2S levels, which may provide a convenient rationale for the application of H2S-targeted therapeutics. Further randomized-controlled trials are warranted to investigate its definitive role.

COVID-19: immunopathology, pathophysiological mechanisms, and treatment options.

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), continues to spread globally despite the worldwide implementation of preventive measures to combat the disease. Although most COVID-19 cases are characterised by a mild, self-limiting disease course, a considerable subset of patients develop a more severe condition, varying from pneumonia and acute respiratory distress syndrome (ARDS) to multi-organ failure (MOF). Progression of COVID-19 is thought to occur as a result of a complex interplay between multiple pathophysiological mechanisms, all of which may orchestrate SARS-CoV-2 infection and contribute to organ-specific tissue damage. In this respect, dissecting currently available knowledge of COVID-19 immunopathogenesis is crucially important, not only to improve our understanding of its pathophysiology but also to fuel the rationale of both novel and repurposed treatment modalities. Various immune-mediated pathways during SARS-CoV-2 infection are relevant in this context, which relate to innate immunity, adaptive immunity, and autoimmunity. Pathological findings in tissue specimens of patients with COVID-19 provide valuable information with regard to our understanding of pathophysiology as well as the development of evidence-based treatment regimens. This review provides an updated overview of the main pathological changes observed in COVID-19 within the most commonly affected organ systems, with special emphasis on immunopathology. Current management strategies for COVID-19 include supportive care and the use of repurposed or symptomatic drugs, such as dexamethasone, remdesivir, and anticoagulants. Ultimately, prevention is key to combat COVID-19, and this requires appropriate measures to attenuate its spread and, above all, the development and implementation of effective vaccines. © 2021 The Authors. The Journal of Pathology published by John Wiley & Sons, Ltd. on behalf of The Pathological Society of Great Britain and Ireland.

The mechanistic overview of SARS-CoV-2 using angiotensin-converting enzyme 2 to enter the cell for replication: possible treatment options related to the renin-angiotensin system.

The SARS-CoV-2 pandemic is a healthcare crisis caused by insufficient knowledge applicable to effectively combat the virus. Therefore, different scientific discovery strategies need to be connected, to generate a rational treatment which can be made available as rapidly as possible. This relies on a solid theoretical understanding of the mechanisms of SARS-CoV-2 infection and host responses, which is coupled to the practical experience of clinicians that are treating patients. Because SARS-CoV-2 enters the cell by binding to angiotensin-converting enzyme 2 (ACE2), targeting ACE2 to prevent such binding seems an obvious strategy to combat infection. However, ACE2 performs its functions outside the cell and was found to enter the cell only by angiotensin II type 1 receptor (AT1R)-induced endocytosis, after which ACE2 is destroyed. This means that preventing uptake of ACE2 into the cell by blocking AT1R would be a more logical approach to limit entry of SARS-CoV-2 into the cell. Since ACE2 plays an important protective role in maintaining key biological processes, treatments should not disrupt the functional capacity of ACE2, to counterbalance the negative effects of the infection. Based on known mechanisms and knowledge of the characteristics of SARS-CoV we propose the hypothesis that the immune system facilitates SARS-CoV-2 replication which disrupts immune regulatory mechanisms. The proposed mechanism by which SARS-CoV-2 causes disease immediately suggests a possible treatment, since the AT1R is a key player in this whole process. AT1R antagonists appear to be the ideal candidate for the treatment of SARS-CoV-2 infection. AT1R antagonists counterbalance the negative consequences of angiotesnin II and, in addition, they might even be involved in preventing the cellular uptake of the virus without interfering with ACE2 function. AT1R antagonists are widely available, cheap, and safe. Therefore, we propose to consider using AT1R antagonists in the treatment of SARS-CoV-2.