Inflammatory metabolite 7α,25-OHC promotes TIMP1 expression in COVID-19 monocytes through synergy effect of SMARCC1/JUND/H3K27ac.

Chromatin remodeling factors are involved in the inflammatory responses, contributing to tissue damage and multi-organ dysfunction in COVID-19 patients. However, the underlying mechanisms remain unclear. In this study, high-dimensional analyses of single-cell RNA sequencing and single-cell ATAC sequencing data revealed increased chromatin accessibility at the promoters or enhancers of the pro-inflammatory cytokine tissue inhibitor of metalloproteinase-1 (TIMP1), as well as altered gene transcription profiles in monocytes from COVID-19 patients. Motif enrichment and positive regulators analyses identified SMARCC1, the core subunit of the chromatin remodeling complex, and the transcription factor JUND as positive regulators to co-modulate TIMP1 expression. In-vitro experiments, co-immunoprecipitation and chromatin immunoprecipitation (ChIP)-qPCR, and others, demonstrated the collaboration of SMARCC1 and JUND. Increased 7α,25-dihydroxycholesterol (7α,25-OHC) enhanced SMARCC1-JUND interactions to co-regulate TIMP1 expression. Further investigation indicated that 7α,25-OHC promoted the expression of SMARCC1 and its co-localization with H3K27ac, which involved in the expression of TIMP1 and inflammatory responses. Our study highlights the critical roles of SMARCC1 and JUND in COVID-19 inflammation, and offers the potential targets for the prevention and treatment of COVID-19.