Anti-COVID-19 Activity of FDA Approved Drugs through RNA G-quadruplex Binding

The COVID-19 pandemic caused by SARS-CoV-2 has caused millions of infections and deaths worldwide. Limited treatment options and the threat from emerging variants underline the need for novel and widely accessible therapeutics. G-quadruplexes (G4s) are nucleic acid secondary structures known to affect many cellular processes including viral replication and transcription. We identified heretofore not reported G4s with remarkably low mutation frequency across >5 million SARS-CoV-2 genomes. The G4 structure was targeted using FDA-approved drugs that can bind G4s - Chlorpromazine (CPZ) and Prochlorperazine (PCZ). We found significant inhibition in lung pathology and lung viral load of SARS-CoV-2 challenged hamsters when treated with CPZ, PCZ that was comparable to the widely used antiviral drug Remdesivir. In support, in vitro G4 binding, inhibition of reverse transcription from RNA isolated from COVID-infected humans, and attenuated viral replication and infectivity in Vero cell cultures were clear in case of both CPZ/PCZ. Apart from the wide accessibility of CPZ/PCZ, targeting relatively invariant nucleic acid structures poses an attractive strategy against fast mutating viruses like SARS-CoV-2.

Prophylactic treatment of Glycyrrhiza glabra mitigates COVID-19 pathology through inhibition of pro-inflammatory cytokines in the hamster model and NETosis.

Severe coronavirus disease (COVID-19) is accompanied with acute respiratory distress syndrome & pulmonary pathology, and is presented mostly with inflammatory cytokine release, dysregulated immune response, skewed neutrophil/ lymphocyte ratio, and hypercoagulable state. Though vaccinations have proved effective in reducing the COVID-19 related mortality, the limitation of use of vaccine against immunocompromised, comorbidity, and emerging variants remains a concern. In the current study we investigate for the first-time the efficacy of Glycyrrhiza glabra (GG) extract, a potent immunomodulator, against SARS-CoV-2 infection in hamsters. Prophylactic treatment with GG showed protection against loss in body weight and 35-40% decrease in lung viral load along with reduced lung pathology in the hamster model. Remarkably, GG reduced the mRNA expression of pro-inflammatory cytokines and Plasminogen activator inhibito-1 (PAI-1). In-vitro, GG acted as potent immunomodulator by reducing Th2 and Th17 differentiation and IL-4 and IL-17A cytokine production. In addition, GG also showed robust potential to suppress ROS, mtROS and NETs generation in a concentration dependent manner in both human polymorphonuclear neutrophils (PMNs) and murine bone marrow derived neutrophils (BMDNs). Taken together, we provide evidence for the protective efficacy of GG against COVID-19 and its putative mechanistic insight, which might be developed as a future immunomodulatory approach against various pathologies with high cytokine production, aberrant neutrophil activation including coronavirus infection.

Innate immune response and distinct metabolomic signatures together drive and shape the SARS-CoV-2-specific T cell response during COVID-19

The underlying factors contributing to the evolution of SARS-CoV-2-specific T cell responses during COVID-19 infection remain unidentified. To address this, we characterized innate and adaptive immune responses with metabolomic profiling longitudinally at three different time points (0-3, 7-9, and 14-16 days post-COVID-19 positivity) from young mildly symptomatic active COVID-19 patients infected during the first wave in mid-2020. We observed that anti-RBD IgG and viral neutralization are significantly reduced against the Delta variant compared to the ancestral strain. In contrast, compared to the ancestral strain, T cell responses remain preserved against the delta and omicron variants. We determined innate immune responses during the early stage of active infection in response to TLR 3/7/8 mediated activation in PBMCs and serum metabolomic profiling. Correlation analysis indicated PBMCs-derived proinflammatory cytokines, IL-18, IL-1{beta}, and IL-23, and the abundance of plasma metabolites involved in arginine biosynthesis were predictive of a robust SARS-CoV-2-specific Th1 response at a later stage (two weeks after PCR positivity). These observations may contribute to designing effective vaccines and adjuvants that promote innate immune responses and metabolites to induce long-lasting anti-SARS-CoV-2 specific T cells response.

Effect of prophylactic use of intra-nasal oil formulations in the hamster model of Covid-19

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV2) infection initiates with viral entry in upper respiratory tract leading to coronavirus disease 2019 (Covid-19). Severe Covid-19 is characterized by pulmonary pathologies associated with respiratory failure. Thus, therapeutics aimed at inhibiting entry of the virus or its internalization in the upper respiratory tract, are of interest. Herein, we report the prophylactic application of two intra-nasal formulations provided by the National Medicinal Plant Board (NMPB), Anu oil and Til tailya in SARS-CoV2 infection hamster model. Prophylactic nasal instillation of these oil formulations exhibited reduced viral load in lungs, and resulted in reduced body weight loss and pneumonitis. In line with reduced viral load, histopathlogical analysis revealed a reduction in lung pathology in Anu oil group as compared to the control infected group. However, Til tailya group did not show a significant reduction in lung pathology. Furthermore, molecular analysis using mRNA expression profiling indicated reduced expression of pro-inflammatory cytokines genes, including Th1 and Th17 cytokines for both the intra-nasal formulations as a result of decreased viral load. Together, the prophylactic intra-nasal application of Annu oil seems to be useful in limiting both the viral load and disease severity disease in SARS-CoV2 infection in hamster model.

Immunological and cardio-vascular pathologies associated with SARS-CoV-2 infection in golden syrian hamster

Severe acute respiratory syndrome coronavirus (SARS-CoV)-2 infection in golden Syrian hamster (GSH) causes lung pathology and resembles human coronavirus disease (Covid-19). However, extra-pulmonary pathologies of SARS-CoV-2 infection that result in long Covid remains undefined in GSH. Here, using in silico modelling we show that hamster angiotensin-converting enzyme-2 (ACE-2) and neuropilin-1 (NRP-1) interaction with SARS-CoV-2 is similar to human. Intranasal SARS-CoV-2 infection in GSH resulted in early onset of lung pathologies marked by aggressive inflammatory response. Remarkably, late phase of SARS-CoV2 infection in GSH showed cardiovascular complications (CVC) characterized by ventricular hypertrophy, ventricular wall thickening, interstitial coronary fibrosis and altered lipidomics with elevated cholesterol, low-density lipoprotein and long chain fatty acid triglycerides. Moreover, serum metabolomics profile of infected GSH correlated with Covid19 patients. Together, we propose GSH as a suitable animal model to study immediate and long Covid19 pathologies that could be extended to therapeutics against Covid19 related CVC.