The severity of SARS-CoV-2 infection in K18-hACE2 mice is attenuated by a novel steroid-derivative in a gender-specific manner

Background and Purpose: COVID-19 infections caused by SARS-CoV-2 disseminated through human-to-human transmission can evoke severe inflammation. Treatments to reduce the SARS-CoV-2-associated inflammation are needed and are the focus of much research. In this study, we investigated the effect of N-ethyl-N′-[(3β,5α)-17-oxoandrostan-3-yl] urea (NEOU), a novel 17α-ketosteroid derivative, on the severity of COVID-19 infections. Experimental Approach: Studies were conducted in SARS-CoV-2-infected K18-hACE2 mice. Key Results: SARS-CoV-2-infected K18-hACE2 mice developed severe inflammatory crises and immune responses along with up-regulation of genes in associated signalling pathways in male more than female mice. Notably, SARS-CoV-2 infection down-regulated genes encoding drug metabolizing cytochrome P450 enzymes in male but not female mice. Treatment with NEOU (1 mg·kg⁻¹·day⁻¹) 24 or 72 h post-viral infection alleviated lung injury by decreasing expression of genes encoding inflammatory cytokines and chemokines while increasing expression of genes encoding immunoglobins. In situ hybridization using RNA scope™ probes and immunohistochemical assays revealed that NEOU increased resident CD169⁺ immunoregulatory macrophages and IBA-1 immunoreactive macrophage-dendritic cells within alveolar spaces in the lungs of infected mice. Consequentially, NEOU reduced morbidity more prominently in male than female mice. However, NEOU increased median survival time and accelerated recovery from infection by 6 days in both males and females. Conclusions and Implications: These findings demonstrate that SARS-CoV-2 exhibits gender bias by differentially regulating genes encoding inflammatory cytokines, immunogenic factors and drug-metabolizing enzymes, in male versus female mice. Most importantly, we identified a novel 17α-ketosteroid that reduces the severity of COVID-19 infection and could be beneficial for reducing impact of COVID-19.