Possible Immunological Mechanisms in COVID-19 Patients with Immune Thrombocytopenic Purpura

Millions of people around the world were, or are still involved with COVID-19 due to infection with SARS-CoV-2. In addition to hallmark symptoms, thrombotic problems, lymphopenia, and thrombocytopenia have also been reported in COVID-19 patients, of which ITP is the most common and occurs in more than one-third of COVID-19 patients. Hyperinflammation, cytokine storms, and generally immune dysregulation in a percentage of patients develop the main consequences of diseases such as ALI, ARDS and multiple organ failure. Some of the important events in the immunopathogenesis of this disease are disruption of T-cell effector differentiation and the destructive role of Th17 lymphocytes, neutrophil function and inflammatory macrophages. NLRP3-inflammasome hyperactivity causes serious dysfunction of innate immune cells and, consequently, T lymphocytes in many inflammatory disorders, most notably in the COVID-19. A closer look at the immunopathogenesis of ITP and COVID-19 brings us to common ground. The purpose of this study was to review and summarize the findings of various studies on the immunopathogenesis of ITP and its possible causes in COVID-19. Finally, enhanced differentiation of Th17 and Th1, the cell death called as pyroptosis, hyperinflammation and dysfunction of inflammatory neutrophils and macrophages, and NLRP3-inflammasome hyperactivity are important factors in the development of thrombocytopenia in patients with COVID-19. Further studies are needed to better understand immunopathogenesis and effective treatments for ITP, especially in inflammatory disorders. © 2022, Opca Bolnica Zadar. All rights reserved.

[Bromhexine is a potential drug for COVID-19; From hypothesis to clinical trials].

COVID-19 (novel coronavirus disease 2019), caused by the SARS-CoV-2 virus, has various clinical manifestations and several pathogenic pathways. Although several therapeutic options have been used to control COVID-19, none of these medications have been proven to be a definitive cure. Transmembrane serine protease 2 (TMPRSS2) is a protease that has a key role in the entry of SARS-CoV-2 into host cells. Following the binding of the viral spike (S) protein to the angiotensin-converting enzyme 2 (ACE2) receptors of the host cells, TMPRSS2 processes and activates the S protein on the epithelial cells. As a result, the membranes of the virus and host cell fuse. Bromhexine is a specific TMPRSS2 inhibitor that potentially inhibits the infectivity cycle of SARS-CoV-2. Moreover, several clinical trials are evaluating the efficacy of bromhexine in COVID-19 patients. The findings of these studies have shown that bromhexine is effective in improving the clinical outcomes of COVID-19 and has prophylactic effects by inhibiting TMPRSS2 and viral penetration into the host cells. Bromhexine alone cannot cure all of the symptoms of SARS-CoV-2 infection. However, it could be an effective addition to control and prevent the disease progression along with other drugs that are used to treat COVID-19. Further studies are required to investigate the efficacy of bromhexine in COVID-19.

Resveratrol;an inflammasome inhibitor and a potential therapy for severe cases of COVID-19

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has infected more than 126 million people worldwide and deaths exceed two million. Virological features of SARS-CoV-2, including its genomic sequence, have been identified but the mechanisms governing coronavirus disease 2019 (COVID-19) immunopathogenesis have remained uncertain. Severe COVID-19 is associated with a cytokine storm, chronic inflammation, neutrophilia, lymphocyte dysfunction, lymphopenia, reduction in T-Iymphocytes and natural killer (NK) cells, disruption in viral clearance, and neutrophil/macrophage infiltration in the lungs. In many cases, patients develop acute lung injury (ALI), acute respiratory distress syndrome (ARDS), and/or multiple-organ dysfunction syndrome (MODS). Resveratrol reduces the expression of inflammasome activators such as thioredoxin-interacting protein (TXNIP) and nuclear factor erythroid 2 (NrF2) and increases that of the inflammasome inhibitor, i.e., NAD-dependent deacetylase sirtuin-1 (SIRT1). Resveratrol is able to inhibit the production of reactive oxygen species (ROS) and the activation of inducible nitric oxide synthases (NOS). It affects signaling pathways including mitogen-activated protein kinase (MAPK) and nuclear factor kappa B (NF-kappa B) thereby further inhibiting inflammasomes. Because of its anti-inflammasome, anti-inflammatory, and anti-oxidant effects and considering the key role of inflammation and cytokine storm in disease severity and poor patient outcomes, it is concluded that resveratrol can be useful in the treatment of COVID-19. Given the persistence of the COVID-19 pandemic and the challenges of extensive vaccination in all countries, it is important to achieve more effective treatments to decrease the mortality rate and severity of severe injuries following COVID-19. Given all the effects reviewed in this article, resveratrol at a dose of up to 600 mg per day can be exploited as a potential adjunctive therapy for COVID-19 patients.