Btbd8 deficiency exacerbates bleomycin-induced pulmonary fibrosis in mice by enhancing myofibroblast accumulation and inflammatory responses.

BTBD8 contributes to the pathogenesis of inflammatory bowel disease through regulating intestinal barrier integrity and inflammation. However, its role in idiopathic pulmonary fibrosis (IPF) remains unknown. Here we investigated whether BTBD8 plays a role in bleomycin-induced pulmonary fibrosis. Pulmonary fibrosis was induced in wild-type (WT) and Btbd8 knockout (KO) mice by intratracheal instillation of bleomycin. The mice were sacrificed on day 7 or 12. Subsequently, the progression of bleomycin-induced pulmonary fibrosis was assessed. We found that Btbd8 KO mice are more susceptible to bleomycin-induced pulmonary fibrosis, with more severe body weight loss and pulmonary injury, increased collagen deposition and myofibroblast accumulation. We further demonstrated that BTBD8 functions in pulmonary fibroblasts to suppress the conversion of fibroblasts to myofibroblasts. Moreover, Btbd8 deficiency promotes the infiltration of inflammatory cells and the secretion of pro-inflammatory cytokines in IPF mouse model. These results highlight the critical role of BTBD8 in the pathogenesis of bleomycin-induced pulmonary fibrosis in mice, and suggest that BTBD8 may alleviate bleomycin-induced fibrosis by suppressing the differentiation of fibroblasts to myofibroblast, as well as inflammatory responses.