RESUMO
The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes Coronavirus Disease 2019 (COVID-19), one of the deadliest medical difficulties to affect people in more than a century. The virus has now spread to many countries worldwide, posing a big challenge to the health status of people in affected populations. Gaining more knowledge about the different aspects of this virus will lead us to better control and treatment methods. In this paper, we discuss the SARS-CoV-2 structure and the mechanism of this virus's entry into host cells through angiotensin-converting enzyme 2 (ACE2), the main receptor for the SARS-CoV-2 virus. The main connection between SARS-CoV-2 and ACE2 is Spike protein. Other topics are also included, like ACE2 structure, functions, and physiology. For instance, ACE2 is involved in the renin-angiotensin-aldosterone system, Angiotensin A/ACE2/Alamandine/MAS-Related GPCR D (MrgD) Axis, the Kinin-Kallikrein System. It also acts as Chaperone Protein for the Amino Acid Transporter, B0AT1, and has a connection with Apelin Peptides. Since ACE2 plays a primary role in COVID-19 pathogenesis, scientists have discovered some SARS-CoV-2 therapy methods based on ACE2 targeting. Tissue expression in different genders and ages, polymorphisms, and host epigenetics, the role of ACE2 in hypertension, and cytokine storm are explained separately.
RESUMO
Cytokine storm refers to the overproduction of immune and inflammatory cells and their proteins (cytokines) [interleukin (IL)-1 and IL-6] causing acute respiratory distress syndrome in COVID-19. COVID-19 causes inflammatory reactions, and patients with COVID-19 had categorized as mild, severe, and critical after reviewing previous studies. Then, it is crucial to find immune-inflammatory indicators that might predict the disorder severity and the prognosis primarily for guiding medical therapy in the face of this unexpectedly developing unique infectious disease. Higher levels of IL-6 and IL-1 levels might be seen in patients with COVID-19 at each stage. In addition, IL-1-induced IL-6 assists in the synthesis of liver C-reactive protein (CRP) in acute phase responses. Recent studies suggested that IL-6 levels are an independent predictor of COVID-19 illness because they were significantly higher in patients with severe than with mild COVID-19 symptoms. Anakinra and tocilizumab (TCZ) are beneficial in lowing mortality in COVID-19 patients; however, information on their safety and efficacy is scarce. The aim of this study was to investigate the role of inflammatory cytokines (IL-1 and IL-6) as potential biomarkers in the different stages (mild, severe, and critical) of COVID-19. A systematic search during the years 2021-2022 using the keywords SARS-CoV-2, COVID-19, IL-6, IL-1, CRP, mild stage, severe stage, critical stage, cytokine storm, tocilizumab, and anakinra was performed in PubMed and Google Scholar databases. This study reviews studies that have investigated the role of high levels of these cytokines in the severity of the disease in patients with COVID-19 and the inhibitory function of TCZ and anakinra in preventing mechanical ventilation and patient mortality. According to the result, studies suggest that decreased innate immune response against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in association with the production of inflammatory cytokines is the determining and driving function of COVID-19.
