Synergistic block of SARS-CoV-2 infection by combined drug inhibition of the host entry factors PIKfyve kinase and TMPRSS2 protease

Abstract

Repurposing FDA-approved inhibitors able to prevent infection by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) could provide a rapid path to establish new therapeutic options to mitigate the effects of coronavirus disease 2019 (COVID-19). Proteolytic cleavages of the spike S protein of SARS-CoV-2, mediated by the host cell proteases cathepsin and TMPRSS2, alone or in combination, are key early activation steps required for efficient infection. The PIKfyve kinase inhibitor apilimod interferes with late endosomal viral traffic, and through an ill-defined mechanism prevents in vitro infection through late endosomes mediated by cathepsin. Similarly, inhibition of TMPRSS2 protease activity by camostat mesylate or nafamostat mesylate prevents infection mediated by the TMPRSS2-dependent and cathepsin-independent pathway. Here, we combined the use of apilimod with camostat mesylate or nafamostat mesylate and found an unexpected ~5-10 fold increase in their effectiveness to prevent SARS-CoV-2 infection in different cell types. Comparable synergism was observed using both, a chimeric vesicular stomatitis virus (VSV) containing S of SARS-CoV-2 (VSV-SARS-CoV-2) and SARS-CoV-2 virus. The substantial ~5 fold or more decrease of half maximal effective concentrations (EC50 values) suggests a plausible treatment strategy based on the combined use of these inhibitors.

The Role of Th17 Response in COVID-19

“…Interaction of SARS-CoV-2 spike protein via the receptor-bind domains (RBDs) with the cell receptor ACE2 induces the endocytosis, and enables entry into many different types of cells, including type II alveolar epithelial cells, monocytes and macrophages. Priming and activation of S protein by the transmembrane serine protease (TMPRSS) 2, TMPRSS4, Factor Xa or by cathepsin is needed in order to facilitate cell surface entry, thus enabling the fusion of SARS-CoV-2 virus with the host cells and viral replication [16,17]. It has been shown that SARS-CoV-2 has 10-20 times higher binding affinity to ACE2 than SARS-CoV, which may result in more effective viral transmission through droplets from individuals with COVID-19.…”

Roles of PIKfyve in multiple cellular pathways

“…Apilimod prevents the infection of cultured cells with Ebola, Marburg and SARS-CoV-2 [ 68 , 69 ]. Based on a large scale screen in mammalian cell lines [ 70 ], as well as several targeted studies [ 71 , 72 , 73 ], apilimod was proposed as a treatment for COVID-19 and is currently undergoing a phase II clinical trial.…”

Cryo-EM structures reveal the activation and substrate recognition mechanism of human enteropeptidase

“…Inhibition of the serine protease becomes a new therapy for the treatment of many diseases, including Alzheimer disease 37 , autoimmunity disease 38 , and even COVID-19 pandemic 39, 40 . The development of specific inhibitor that selectively target EP maybe a strategy to the clinical intervention of pancreatitis 10 .…”