Pulmonary fibrosis (PF) can arise from unknown causes, as in idiopathic PF, or as a consequence of infections, including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Current treatments for PF slow, but do not stop, disease progression. We report that treatment with a runt-related transcription factor 1 (RUNX1) inhibitor (Ro24-7429), previously found to be safe, although ineffective, as a Tat inhibitor in patients with HIV, robustly ameliorates lung fibrosis and inflammation in the bleomycin-induced PF mouse model. RUNX1 inhibition blunted fundamental mechanisms downstream pathologic mediators of fibrosis and inflammation, including transforming growth factor-β1 and tumor necrosis factor-α, in cultured lung epithelial cells, fibroblasts, and vascular endothelial cells, indicating pleiotropic effects. RUNX1 inhibition also reduced the expression of angiotensin-converting enzyme 2 and FES Upstream Region (FURIN), host proteins critical for SARS-CoV-2 infection, in mice and in vitro. A subset of human lungs with SARS-CoV-2 infection overexpress RUNX1. These data suggest that RUNX1 inhibition via repurposing of Ro24-7429 may be beneficial for PF and to battle SARS-CoV-2, by reducing expression of viral mediators and by preventing respiratory complications.
