Anti-SARS-CoV-2 and anti-cytokine storm neutralizing antibody therapies against COVID-19: Update, challenges, and perspectives

Enterococcus faecium C171: Modulating the Immune Response to Acute Lethal Viral Challenge

Commensal bacteria modulate acute immune responses to infection in hosts. In this study, Enterococcus faecium C171 was screened and isolated. This strain has similar basic characteristics to the reference probiotic, including strong anti-inflammatory and anti-infective effects. E. faecium C171 inhibits the production of pro-Caspase-1 and significantly reduces the production of interleukin-1β (IL-1β) in vitro. These reactions were confirmed using the Transwell system. Live E. faecium C171 mainly exerted an inhibitory effect on acute inflammation, whereas the anti-infective and immune-activating effects were primarily mediated by the E. faecium C171-produced bacterial extracellular vesicles (Efm-C171-BEVs). Furthermore, in the specific pathogen-free (SPF) chicken model, oral administration of E. faecium C171 increased the relative abundance of beneficial microbiota (Enterococcus and Lactobacillus), particularly Enterococcus, the most important functional bacteria of the gut microbiota. E. faecium C171 significantly inhibited the acute inflammatory response induced by a highly virulent infectious disease, and reduced mortality in SPF chickens by 75%. In addition, E. faecium C171 induced high levels of CD3+, CD4-, and CD8- immunoregulatory cells and CD8+ killer T cells, and significantly improved the proliferative activity of T cells in peripheral blood mononuclear cells, and the secretion of interferon-γ. These findings indicate that E. faecium C171 and Efm-C171-BEVs are promising candidates for adjuvant treatment of acute inflammatory diseases and acute viral infections.

New Insights into the Identification of Metabolites and Cytokines Predictive of Outcome for Patients with Severe SARS-CoV-2 Infection Showed Similarity with Cancer

SARS-CoV-2 infection is characterized by several clinical manifestations, ranging from the absence of symptoms to severe forms that necessitate intensive care treatment. It is known that the patients with the highest rate of mortality develop increased levels of proinflammatory cytokines, called the "cytokine storm", which is similar to inflammatory processes that occur in cancer. Additionally, SARS-CoV-2 infection induces modifications in host metabolism leading to metabolic reprogramming, which is closely linked to metabolic changes in cancer. A better understanding of the correlation between perturbed metabolism and inflammatory responses is necessary. We evaluated untargeted plasma metabolomics and cytokine profiling via ¹H-NMR (proton nuclear magnetic resonance) and multiplex Luminex assay, respectively, in a training set of a limited number of patients with severe SARS-CoV-2 infection classified on the basis of their outcome. Univariate analysis and Kaplan-Meier curves related to hospitalization time showed that lower levels of several metabolites and cytokines/growth factors, correlated with a good outcome in these patients and these data were confirmed in a validation set of patients with similar characteristics. However, after the multivariate analysis, only the growth factor HGF, lactate and phenylalanine retained a significant prediction of survival. Finally, the combined analysis of lactate and phenylalanine levels correctly predicted the outcome of 83.3% of patients in both the training and the validation set. We highlighted that the cytokines and metabolites involved in COVID-19 patients' poor outcomes are similar to those responsible for cancer development and progression, suggesting the possibility of targeting them by repurposing anticancer drugs as a therapeutic strategy against severe SARS-CoV-2 infection.

Phase III randomized clinical trial of BV ‐4051, an Ayurvedic polyherbal formulation in moderate SARS‐CoV ‐2 infections and its impact on inflammatory biomarkers

SARS-CoV-2 virus and its variants continue to be a challenge inspite of widespread vaccination and preventive measures. We hypothesized an oral, safe polyherbal formulation with antiinflammatory properties may improve the clinical outcome of this disease. BV-4051, a formulation from four Ayurvedic plants namely Ashwagandha, Boswellia, Ginger and Turmeric was used for the treatment of hospitalized moderate COVID-19 patients along with standard of care (SOC). Patients were randomly assigned to receive BV-4051 or placebo tablets for 14 days, at four sites in India during late 2020 to early 2021. Among 208 randomized subjects, 175 completed the study. In BV-4051 group the mean reduction in duration of illness (p = 0.036), alleviation and severity scores of several symptoms like fever, cough, smell, and taste disorders were statistically significant (p ≤ 0.05). A sub-set analysis of subjects treated with or without Remdesivir as SOC showed mean reduction in duration of illness in BV-4051 (p = 0.030), and severity scores (p ≤ 0.05). Mean difference in Interleukin-6 was statistically significant (p = 0.042) on BV-4051 without Remdesivir. BV-4051 may reduce duration of illness, symptoms severity, Interleukin-6, and prevent the incidence of COVID-19 complications. It may have an adjunctive effect with other SOC. Larger extensive clinical testing may give a better understanding of its effect.

A Review of Potential Therapeutic Strategies for COVID-19

Coronavirus disease 2019 is a rather heterogeneous disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The ongoing pandemic is a global threat with increasing death tolls worldwide. SARS-CoV-2 belongs to lineage B β-CoV, a subgroup of Sarbecovirus. These enveloped, large, positive-sense single-stranded RNA viruses are easily spread among individuals, mainly via the respiratory system and droplets. Although the disease has been gradually controlled in many countries, once social restrictions are relaxed the virus may rebound, leading to a more severe and uncontrollable situation again, as occurred in Shanghai, China, in 2022. The current global health threat calls for the urgent development of effective therapeutic options for the treatment and prevention of SARS-CoV-2 infection. This systematic overview of possible SARS-CoV-2 therapeutic strategies from 2019 to 2022 indicates three potential targets: virus entry, virus replication, and the immune system. The information provided in this review will aid the development of more potent and specific antiviral compounds.

Structural insights revealed by crystal structure of B38-CAP, an isoenzyme of carboxypeptidase ACE2, the receptor of SARS-CoV-2

The worldwide pandemic of Coronavirus disease 2019 (COVID-19) is triggered by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and further worsened by the emergence of a variety of SARS-CoV-2 variants. Angiotensin-converting enzyme 2 (ACE2), a carboxypeptidase of M32 family, serves as the receptor of SARS-CoV-2 and key regulator of host renin-angiotensin system (RAS), both of which are mainly mediated via the carboxypeptidase domain of ACE2 (sACE2) or its activity. sACE2 is thus promising in the treatment of COVID-19 but unfortunately weakened by its unstrigent substrate preference and complex interplay with host RAS. B38-CAP, an isoenzyme of ACE2, partically compensates these defects but still encounters the problem related to carboxypeptidase activity and specificity. In this study, we firstly determined the crystal structure of B38-CAP at a resolution of 2.44 Å which exists in dimeric form with the non-crystallographic two-fold axis being in coincidence with the crystallographic two-fold axis. Further structural analysis revealed the structural conservatism feature among M32 family, particularly the catalytic core and moreover lead us to hypothesize that conformational flexibility might play an pivotal role in the catalysis of B38-CAP and ACE2. The work provided here presents key features of the M32 family carboxypeptidase and provides structural basis for further development of B38-CAP-based anti-SARS-CoV-2 drugs.

Mesenchymal stem/stromal cell therapy for COVID-19 pneumonia: potential mechanisms, current clinical evidence, and future perspectives

The coronavirus disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has spread into more than 200 countries and infected approximately 203 million people globally. COVID-19 is associated with high mortality and morbidity in some patients, and this disease still does not have effective treatments with reproducibly appreciable outcomes. One of the leading complications associated with COVID-19 is acute respiratory distress syndrome (ARDS); this is an anti-viral host inflammatory response, and it is usually caused by a cytokine storm syndrome which may lead to multi-organ failure and death. Currently, COVID-19 patients are treated with approaches that mostly fall into two major categories: immunomodulators, which promote the body's fight against viruses efficiently, and antivirals, which slow or stop viruses from multiplying. These treatments include a variety of novel therapies that are currently being tested in clinical trials, including serum, IL-6 antibody, and remdesivir; however, the outcomes of these therapies are not consistently appreciable and remain a subject of debate. Mesenchymal stem/stromal cells (MSCs), the multipotent stem cells that have previously been used to treat viral infections and various respiratory diseases such as ARDS exhibit immunomodulatory properties and can ameliorate tissue damage. Given that SARS-CoV-2 targets the immune system and causes tissue damage, it is presumable that MSCs are being explored to treat COVID-19 patients. This review summarizes the potential mechanisms of action of MSC therapy, progress of MSC, and its related products in clinical trials for COVID-19 therapy based on the outcomes of these clinical studies.

Enzyme-Linked Immunosorbent Assay: An Adaptable Methodology to Study SARS-CoV-2 Humoral and Cellular Immune Responses

The Enzyme-Linked Immunosorbent Assay is a versatile technique, which can be used for several applications. It has enormously contributed to the study of infectious diseases. This review highlights how this methodology supported the science conducted in COVID-19 pandemics, allowing scientists to better understand the immune response against SARS-CoV-2. ELISA can be modified to assess the functionality of antibodies, as avidity and neutralization, respectively by the standardization of avidity-ELISA and surrogate-neutralization methods. Cellular immunity can also be studied using this assay. Products secreted by cells, like proteins and cytokines, can be studied by ELISA or its derivative Enzyme-linked immunospot (ELISpot) assay. ELISA and ELISA-based methods aided the area of immunology against infectious diseases and is still relevant, for example, as a promising approach to study the differences between natural and vaccine-induced immune responses against SARS-CoV-2.

Indirect-Acting Pan-Antivirals vs. Respiratory Viruses: A Fresh Perspective on Computational Multi-Target Drug Discovery

Respiratory viruses continue to afflict mankind. Among them, pathogens such as coronaviruses [including the current pandemic agent known as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)] and the one causing influenza A (IAV) are highly contagious and deadly. These can evade the immune system defenses while causing a hyperinflammatory response that can damage different tissues/organs. Simultaneously targeting immunomodulatory proteins is a plausible antiviral strategy since it could lead to the discovery of indirect-acting pan-antiviral (IAPA) agents for the treatment of diseases caused by respiratory viruses. In this context, computational approaches, which are an essential part of the modern drug discovery campaigns, could accelerate the identification of multi-target immunomodulators. This perspective discusses the usefulness of computational multi-target drug discovery for the virtual screening (drug repurposing) of IAPA agents capable of boosting the immune system through the activation of the toll-like receptor 7 (TLR7) and/or the stimulator of interferon genes (STING) while inhibiting key pro-inflammatory proteins, such as caspase-1 and tumor necrosis factor-alpha (TNF-α).