The Immune Response and Effectiveness of COVID-19 Therapies

The COVID-19 Pandemic: SARS-CoV-2 Structure, Infection, Transmission, Symptomology, and Variants of Concern

Since it was first detected in December 2019, the COVID-19 pandemic has spread across the world and affected virtually every country and territory. The pathogen driving this pandemic is SARS-CoV-2, a positive-sense single-stranded RNA virus which is primarily transmissible though the air and can cause mild to severe respiratory infections in humans. Within the first year of the pandemic, the situation worsened with the emergence of several SARS-CoV-2 variants. Some of these were observed to be more virulent with varying capacities to escape the existing vaccines and were, therefore, denoted as variants of concern. This chapter provides a general overview of the course of the COVID-19 pandemic up to April 2022 with a focus on the structure, infection, transmission, and symptomology of the SARS-CoV-2 virus. The main objectives were to investigate the effects of the variants of concern on the trajectory of the virus and to highlight a potential pathway for coping with the current and future pandemics.

The therapeutic potential of regulatory T cells in reducing cardiovascular complications in patients with severe COVID-19

The SARS coronavirus 2 (SARS CoV-2) causes Coronavirus Disease (COVID-19), is an emerging viral infection. SARS CoV-2 infects target cells by attaching to Angiotensin-Converting Enzyme (ACE2). SARS CoV-2 could cause cardiac damage in patients with severe COVID-19, as ACE2 is expressed in cardiac cells, including cardiomyocytes, pericytes, and fibroblasts, and coronavirus could directly infect these cells. Cardiovascular disorders are the most frequent comorbidity found in COVID-19 patients. Immune cells such as monocytes, macrophages, and T cells may produce inflammatory cytokines and chemokines that contribute to COVID-19 pathogenesis if their functions are uncontrolled. This causes a cytokine storm in COVID-19 patients, which has been associated with cardiac damage. Tregs are a subset of immune cells that regulate immune and inflammatory responses. Tregs suppress inflammation and improve cardiovascular function through a variety of mechanisms. This is an exciting research area to explore the cellular, molecular, and immunological mechanisms related to reducing risks of cardiovascular complications in severe COVID-19. This review evaluated whether Tregs can affect COVID-19-related cardiovascular complications, as well as the mechanisms through which Tregs act.

Multiplex Technologies in COVID-19 Research, Diagnostics, and Prognostics: Battling the Pandemic

Due to continuous technical developments and new insights into the high complexity of infectious diseases such as COVID-19, there is an increasing need for multiplex biomarkers to aid clinical management and support the development of new drugs and vaccines. COVID-19 disease requires rapid diagnosis and stratification to enable the most appropriate treatment course for the best possible outcomes for patients. In addition, these tests should be rapid, specific, and sensitive. They should rule out other potential causes of illness with simultaneous testing for other diseases. Elevated levels of specific biomarkers can be used to establish severity risks of chronic diseases so that patients can be provided the proper medication at the right time. This review describes the state-of-the-art technologies in proteomics, transcriptomics, and metabolomics, for multiplex biomarker approaches in COVID-19 research.

Research Status of the Safety and Efficacy of Mesenchymal Stem Cells in the Treatment of COVID-19-Related Pneumonia: A Systematic Review and Meta-Analysis

Mesenchymal stem cell (MSC) therapy is considered one of the most promising treatments in the context of the coronavirus disease 2019 (COVID-19) pandemic. However, the safety and effectiveness of MSCs in the treatment of COVID-19-associated pneumonia patients need to be systematically reviewed and analyzed. Two independent researchers searched for relevant studies published between October 2019 and April 2021 in the PubMed, Embase, Cochrane Library, WAN FANG, and CNKI databases. All relevant randomized controlled trials, clinically controlled studies, retrospective studies, case reports, letters (with valid data), and case series were included in this meta-analysis. A fixed-effects model and 95% confidence interval (CI) were used to analyze the results. A total of 22 studies involving 371 patients were included in the present study. Allogeneic MSCs from umbilical cord, adipose tissue, menstrual blood, placental tissue, Wharton's jelly, or unreported sources were administered in 247 participants. Combined results revealed that MSC therapy significantly reduced the incidence of adverse events [AEs; odds ratio (OR) = 0.43, 95% CI = 0.22-0.84, P = 0.01] and mortality (OR = 0.17, 95% CI = 0.06-0.49, P < 0.01), and the difference compared with control group was statistically significant. No serious MSC treatment-related AEs were reported. Lung function, radiographic outcomes, and inflammation- and immunity-related biomarker levels all showed improving trends. Therefore, MSC therapy is an effective and safe method for the treatment of COVID-19-associated pneumonia and shows advantages in reducing AEs and mortality. However, a standard and effective MSC treatment program must be developed.

The Role of Alveolar Edema in COVID-19

The coronavirus disease 2019 (COVID-19) has spread over the world for more than one year. COVID-19 often develops life-threatening hypoxemia. Endothelial injury caused by the viral infection leads to intravascular coagulation and ventilation-perfusion mismatch. However, besides above pathogenic mechanisms, the role of alveolar edema in the disease progression has not been discussed comprehensively. Since the exudation of pulmonary edema fluid was extremely serious in COVID-19 patients, we bring out a hypothesis that severity of alveolar edema may determine the size of poorly-ventilated area and the blood oxygen content. Treatments to pulmonary edema (conservative fluid management, exogenous surfactant replacements and ethanol–oxygen vapor therapy hypothetically) may be greatly helpful for reducing the occurrences of severe cases. Given that late mechanical ventilation may cause mucus (edema fluid) to be blown deep into the small airways, oxygen therapy should be given at the early stages. The optimal time and blood oxygen saturation (SpO₂) threshold for oxygen therapy are also discussed.