Caspases in COVID-19 Disease and Sequela and the Therapeutic Potential of Caspase Inhibitors

At present, there are is no effective vaccine and only one FDA approved early-stage therapy against infection with the SARS-CoV-2 virus to prevent disease progression. The excessive inflammation and tissue damage associated with COVID-19 can lead to immediate (i.e. respiratory failure, sepsis, and ultimately, death) or long-term health problems (i.e. fatigue, dyspnea, cough, joint pain, anosmia) and the risk for these complications are higher in the elderly population, certain ethnic groups, as well as those with various co-morbid conditions. Cellular caspases play a role in the pathophysiology of a number of disorders that overlap with the list of co-morbid conditions seen in severe COVID-19. In this study, we assessed transcriptional states of caspases in immune cells from COVID-19 patients and profiled intra-cellular caspases in immune cells and red blood cells derived from a spectrum of COVID-19 patients hospitalized with acute disease or convalescent. Gene expression levels of select caspases were increased in in vitro SARS-CoV-2 infection models and single cell RNA-Seq data of peripheral blood from COVID-19 patients showed a distinct pattern of caspase expression in T cell, neutrophils, and dendritic cells. Flow cytometric evaluation of CD4 T cells showed up-regulation of caspase-1 in hospitalized COVID-19 patients compared to unexposed controls, with the exception of a subset of patients with asthma and chronic rhinosinusitis (CRS). Convalescent COVID-19 patients with lingering symptoms (long haulers) showed persistent up-regulation of caspase-1 in CD4 T cells that was attenuated ex vivo following co-culture with a select pan-caspase inhibitor. Further, we observed elevated caspase 3 levels in red blood cells from COVID-19 patients compared to controls that were responsive to caspase inhibition. Taken together, our results expose an exuberant caspase response in COVID-19 that may facilitate immune-related pathological processes leading to severe outcomes. Pan-caspase inhibition could emerge as a therapeutic strategy to ameliorate, reduce, or prevent severe COVID-19 outcomes.