Inhibition of SARS-CoV-2 infections of human lungs by functional inhibitors of the acid sphingomyelinase

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Preclinical and clinical evidence: Several pre-clinical and clinical studies demonstrated that certain antidepressants prevent the infection of human cells with SARS-CoV-2 and the development of severe symptoms, ventilation or death. These antidepressants are functional inhibitors of the acid sphingomyelinase (FIASMA). We have shown that infection of human epithelial cells with SARS-CoV-2 results in activation of the acid sphingomyelinase, a release of ceramide and the formation of ceramide-enriched membrane platforms in the outer leaflet of the plasma membrane. Inhibition of the acid sphingomyelinase by antidepressants or genetic knock-down of the acid sphingomyelinase using shRNA prevents these biochemical changes and blocks infection with SARS-CoV-2. In turn, reconstitution of ceramide in cells treated with these antidepressants restores infection proving the important role of the acid sphingomyelinase-ceramide system for SARS-CoV-2 infections. These data were confirmed by three independent studies.A multicenter observational retrospective study with more than 7,000 patients, two small and one large prospective, randomized, placebo-controlled clinical trials confirmed that inhibition of the acid sphingomyelinase by antidepressants greatly reduced the risk of patients to develope severe COVID-19.However, at present it is unknown whether antidepressants also inhibit infection of human cells with newly emerging SARS-CoV-2 variants of concern, which is obviously of great importance. The present proposal aims to clarify this issue.Main research question and aims: Recent studies indicate that several spike mutants are resistant to antibodies against SARS-CoV-2 and potentially resistant to vaccines. We will infect cultured primary and freshly-isolated human nasal epithelial cells and freshly-isolated human lung specimen (bronchi and alveolar tissue) with VSV or lentiviral pseudotypes, presenting wildtype or the B.1.1.7-, B.1.351-, P.1- or B.1.617.2-variants of spike, or authentic SARS-CoV-2 virus (wildtype and the variants B.1.1.7 and B.1.617.2). We will test whether pseudotypes presenting wildtype or variants of spike or authentic SARS-CoV-2 activate the acid sphingomyelinase/ceramide system. Most importantly, we will define whether inhibition of the acid sphingomyelinase/ceramide system, using antidepressants or several genetic systems, prevents infection of human cells and lung tissue with pseudotypes presenting wildtype and variants of spike and authentic wildtype virus and virus variants of concern. We will test a panel of functional inhibitors of the acid sphingomyelinase in the inhibition experiments. Antidepressants could be immediately used in clinical studies to prevent or treat COVID-19.