Xuanfei Baidu Decoction protects against macrophages induced inflammation and pulmonary fibrosis via inhibiting IL-6/STAT3 signaling pathway

Ethnopharmacological relevance: Xuanfei Baidu Decoction (XFBD), one of the "three medicines and three pre-scriptions" for the clinically effective treatment of COVID-19 in China, plays an important role in the treatment of mild and/or common patients with dampness-toxin obstructing lung syndrome. Aim of the study: The present work aims to elucidate the protective effects and the possible mechanism of XFBD against the acute inflammation and pulmonary fibrosis. Methods: We use TGF-beta 1 induced fibroblast activation model and LPS/IL-4 induced macrophage inflammation model as in vitro cell models. The mice model of lung fibrosis was induced by BLM via endotracheal drip, and then XFBD (4.6 g/kg, 9.2 g/kg) were administered orally respectively. The efficacy and molecular mechanisms in the presence or absence of XFBD were investigated. Results: The results proved that XFBD can effectively inhibit fibroblast collagen deposition, down-regulate the level of alpha-SMA and inhibit the migration of fibroblasts. IL-4 induced macrophage polarization was also inhibited and the secretions of the inflammatory factors including IL6, iNOS were down-regulated. In vivo experiments, the results proved that XFBD improved the weight loss and survival rate of the mice. The XFBD high-dose administration group had a significant effect in inhibiting collagen deposition and the expression of alpha-SMA in the lungs of mice. XFBD can reduce bleomycin-induced pulmonary fibrosis by inhibiting IL-6/STAT3 activation and related macrophage infiltration. Conclusions: Xuanfei Baidu Decoction protects against macrophages induced inflammation and pulmonary fibrosis via inhibiting IL-6/STAT3 signaling pathway.