Rhoifolin improves bleomycin-induced fibrosis in vivo and cell damage in vitro both related to NRF2/HO-1 pathway

Pulmonary fibrosis (PF) is a chronic interstitial lung illness characterized by its high worldwide prevalence, unknown etiology, and dismal prognosis. Lonicerae Japonicae Flos, a commonly used traditional Chinese medicine for treating PF, is rich in Rhoifolin (ROF). Although numerous studies have demonstrated the anti-inflammatory properties of ROF, its potential anti-fibrotic effects remain uncertain. In this study, we established a PF model in Sprague-Dawley (SD) rats utilizing Bleomycin (BLM). We then assessed the impact of ROF on lung histology and appearance, measured the content level of Superoxide dismutase (SOD) in rat serum, and analyzed changes in α-SMA, TGF-β relative mRNA expression using PCR, measured SMAD Family Member 7 (Smad7), and Heme Oxygenase-1 (HO-1) protein expression in rat lung tissue by Western Blot. Additionally, we induced a cell injury model in A549 cells with BLM. Then after ROF administration, we detected the cell viability by MTT assay, measured N-cadherin, α-SMA, and Vimentin mRNA levels via real-time PCR, and analyzed the expression changes of N-cadherin, Nuclear factor erythroid 2-related factor 2(Nrf2), HO-1, Smad7 proteins by Western Blot. The results indicated that ROF mitigated lung tissue damage and reduced the degree of PF in the lung tissue of rats with PF. Furthermore, In vivo, ROF reduced the expression of N-cadherin protein while increasing the expression of Smad7, and HO-1 proteins and decreasing the relative mRNA expression of α-SMA and TGF-β, and increased the expresson of SOD in rat serum In vitro, cell injury was induced in A549 cells using BLM. After ROF administration, the relative mRNA expression of α-SMA, N-cadherin, and Vimentin decreased significantly, and the protein expression of N-cadherin decreased, while the protein expression of Nrf2, HO-1, and Smad7 increased significantly. This study demonstrates that ROF can mitigate the symptoms of PF to a certain degree, and its mechanism of action is intimately linked to the Nrf2/HO-1 signaling pathway. Therefore, this study indicates that ROF may serve as a potential therapeutic agent for treating PF. Not applicable.