Rapamycin as a potential repurpose drug candidate for the treatment of COVID-19

Blockade of SARS-CoV-2 infection in vitro by highly potent PI3K-α/mTOR/BRD4 inhibitor

Pathogenic viruses like SARS-CoV-2 and HIV hijack the host molecular machinery to establish infection and survival in infected cells. This has led the scientific community to explore the molecular mechanisms by which SARS-CoV-2 infects host cells, establishes productive infection, and causes life-threatening pathophysiology. Very few targeted therapeutics for COVID-19 currently exist, such as remdesivir. Recently, a proteomic approach explored the interactions of 26 of 29 SARS-CoV-2 proteins with cellular targets in human cells and identified 67 interactions as potential targets for drug development. Two of the critical targets, the bromodomain and extra-terminal domain proteins (BETs): BRD2/BRD4 and mTOR, are inhibited by the dual inhibitory small molecule SF2523 at nanomolar potency. SF2523 is the only known mTOR PI3K-α/(BRD2/BRD4) inhibitor with potential to block two orthogonal pathways necessary for SARS-CoV-2 pathogenesis in human cells. Our results demonstrate that SF2523 effectively blocks SARS-CoV-2 replication in lung bronchial epithelial cells in vitro , showing an IC ₅₀ value of 1.5 µM, comparable to IC ₅₀ value of remdesivir (1.1 µM). Further, we demonstrated that the combination of doses of SF2523 and remdesivir is highly synergistic: it allows for the reduction of doses of SF2523 and remdesivir by 25-fold and 4-fold, respectively, to achieve the same potency observed for a single inhibitor. Because SF2523 inhibits two SARS-CoV-2 driven pathogenesis mechanisms involving BRD2/BRD4 and mTOR signaling, our data suggest that SF2523 alone or in combination with remdesivir could be a novel and efficient therapeutic strategy to block SARS-CoV-2 infection and hence be beneficial in preventing severe COVID-19 disease evolution.

One Sentence Summary

Evidence of in silico designed chemotype (SF2523) targeting PI3K-α/mTOR/BRD4 inhibits SARS-CoV-2 infection and is highly synergistic with remdesivir.

A novel approach to minimize the false negative COVID-19 diagnosis by inclusion of specific cell markers and multiple sample collection

The SARS-CoV-2 pandemic has caused unpredictable mortality and economic losses globally. With no approved drug for the treatment, the accurate diagnosis of COVID-19 becomes essential. RNA based test takes several hours and require extensive human intervention for RNA extraction and RT-PCR, but it is preferred over the antibody-based detection as the latter does not detect the early stage infections. The RT-PCR being a gold standard of COVID-19 diagnosis offers highly standardized detection of the SARS-CoV-2 RNA, still vulnerable for false-negative diagnosis due to absence of infected cells in the sample or inaccurate RNA extraction. Hence there is a need to develop alternative protocols and methods for the accurate COVID-19 diagnosis. Here we propose two additional steps in RT-PCR based COVID-19 diagnosis to minimize false-negative detection. The first step involves collection of four samples from an individual. Each sample should be collected from nasopharyngeal and oropharyngeal regions on day 01, mixed together followed by RNA extraction and then repeating the same exercise on day 03. The RNA extracted on day 01 and day 03 must be pooled together to be used in the RT-PCR. Second, we propose the inclusion of the control marker genes specific to nasal goblet cell, type-II pneumocyte and absorptive enterocytes to ensure the specificity of the RNA source. Overall, these additional steps in the proposed method would increase the chances of SARS-CoV-2 detection in the infected population and would limit the false-negative diagnosis of COVID-19 and hence the spread of this disease.•RT-PCR based COVID-19 diagnosis is vulnerable to the false-negative results due to inaccurate sample isolation or RNA extraction.•RNA pool of multiple samples from an individual improves the chances of detection of SARS-CoV-2 by RT-PCR.•Inclusion of specific marker genes would ensure the right RNA source from the desired cell.

mTOR inhibition: a double-edged sword in patients with COVID-19?

The current COVID-19 is one of the deadliest pandemics in recent decades. In the lack of a specific treatment for this novel infection, knowing the role of cell signaling pathways in the pathogenesis of this infection could be useful in finding effective drugs against this disease. The mammalian or mechanistic target of rapamycin (mTOR) is an important cell signaling pathway that has important role in the regulation of cell growth, protein synthesis, and metabolism in reactance to upstream signals in both pathological and normal physiological conditions. Recently, some researchers have suggested the therapeutic potential of mTOR inhibitors such as rapamycin against COVID-19. However, it is important to consider the role of activation of this pathway in controlling immune system response against viral activity in drug repositioning of rapamycin and other mTOR inhibitors in SARS-CoV-2 infection.

Possible Therapeutic Use of Natural Compounds Against COVID-19

The outbreak of severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) has led to coronavirus disease-19 (COVID-19); a pandemic disease that has resulted in devastating social, economic, morbidity and mortality burdens. SARS-CoV-2 infects cells following receptor-mediated endocytosis and priming by cellular proteases. Following uptake, SARS-CoV-2 replicates in autophagosome-like structures in the cytosol following its escape from endolysosomes. Accordingly, the greater endolysosome pathway including autophagosomes and the mTOR sensor may be targets for therapeutic interventions against SARS-CoV-2 infection and COVID-19 pathogenesis. Naturally existing compounds (phytochemicals) through their actions on endolysosomes and mTOR signaling pathways might provide therapeutic relief against COVID-19. Here, we discuss evidence that some natural compounds through actions on the greater endolysosome system can inhibit SARS-CoV-2 infectivity and thereby might be repurposed for use against COVID-19.