Obaculactone protects against bleomycin-induced pulmonary fibrosis in mice

• Obaculactone ameliorates bleomycin-induced pulmonary fibrosis in mice.
• Obaculactone mitigates bleomycin-induced inflammatory response in lungs.
• Obaculactone exerts inhibitory effects on TGF-β1 signaling and TGF-β1-induced EMT progress.

Idiopathic pulmonary fibrosis is a progressive, degenerative and almost irreversible disease. There is hardly an effective cure for lung damage due to pulmonary fibrosis. The purpose of this study was to evaluate the role of obaculactone in an already-assessed model of idiopathic pulmonary fibrosis induced by bleomycin administration. Mice were subjected to intratracheal instillation of bleomycin, and obaculactone was given orally after bleomycin instillation daily for 23 days. Treatment with obaculactone ameliorated body weight loss, lung histopathology abnormalities and pulmonary collagen deposition, with a decrease of the inflammatory cell number and the cytokine level in bronchoalveolar lavage fluid. Moreover, obaculactone inhibited the expression of icam1, vcam1, inos and cox2, and attenuated oxidative stress in bleomycin-treated lungs. Importantly, the production of collagen I and α-SMA in lung tissues as well as the levels of TGF-β1, ALK5, p-Smad2 and p-Smad3 in lung homogenates was also reduced after obaculactone treatment. Finally, the TGF-β1-induced epithelial-mesenchymal transition via Smad-dependent and Smad-independent pathways was reversed by obaculactone. Collectively, these data suggest that obaculactone may be a promising drug candidate for the treatment of idiopathic pulmonary fibrosis.