Lanatoside C protects mice against bleomycin‐induced pulmonary fibrosis through suppression of fibroblast proliferation and differentiation

Summary It has been established that lanatoside C, a FDA ‐approved cardiac glycoside, reduces proliferation of cancer cell lines. The proliferation of fibroblasts is critical to the pathogenesis of pulmonary fibrosis ( PF ), a progressive and fatal fibrotic lung disease lacking effective treatment. In this study we have investigated the impact of lanatoside C on a bleomycin ( BLM )‐induced mouse model of PF and through the evaluation of fibroblast proliferation and activation in vitro. We evaluated explanted lung tissue by histological staining, western blot analysis, qRT ‐ PCR and survival analysis, demonstrating that lanatoside C was able to protect mice against BLM ‐induced pulmonary fibrosis. The proliferation of cultured pulmonary fibroblasts isolated from BLM ‐induced PF mice was suppressed by lanatoside C, as hypothesized, through the induction of cell apoptosis and cell cycle arrest at the G2/M phase. The Akt signalling pathway was involved in this process. Interestingly, the production of α‐ SMA , fibronectin, and collagen I and III in response to TGF ‐β1 in healthy mouse fibroblasts was suppressed following lanatoside C administration by inhibition of TGF ‐β1/Smad signalling. In addition, TGF ‐β1‐induced migration in lung fibroblasts was also impeded after lanatoside C treatment. Together, our data revealed that lanatoside C alleviated BLM ‐induced pulmonary fibrosis in mice via attenuation of growth and differentiation of fibroblasts, suggesting that it has potential as a candidate therapy for PF patients.