Inhibiting autophagy affects collagen degradation by TGF-β1 in the bronchial fibroblasts of rats

Abstract

Chronic obstructive pulmonary disease (COPD) is a major global health issue and its prevalence is growing. Importantly, autophagy plays a crucial role in the pathophysiology of airway remodeling. However, further research is required to determine the precise mechanism of autophagy in rat bronchial fibroblasts (RBFs). In this study, we selected transforming growth factor-β1 (TGF-β1) as a proliferation stimulating agent and explored its impact on RBFs-related collagen degradation following autophagy. We used enzyme digestion combined with tissue block adhesion to quickly and efficiently isolate and extract RBFs. We then established autophagy models of RBFs using rapamycin and starvation. Subsequently, we used western blotting (WB) to detect the expression of autophagy-related proteins (LC3-II, Beclin-1, and P62) in RBFs treated with TGF-β1. Further, we used an enzyme-linked immunosorbent assay (ELISA) to measure the level of matrix metalloproteinase-1 (MMP-1) and its inhibitor, matrix metalloproteinase inhibitor-1 (TIMP-1) in the RBF supernatant. Different concentrations of TGF-β1 promoted RBF growth, while rapamycin lowered RBF survival rates. TGF-β1 downregulated LC3-II and Beclin1 expression but increased P62 expression levels after rapamycin and starvation-induced autophagy in RBFs. Adding TGF-β1 elevated TIMP-1 protein levels and reduced MMP-1 protein levels. The present study provides novel insights that TGF-β1 reduces airway emodeling in RBFs by inhibiting autophagy and collagen degradation, suggesting that targeting TGF-β1 might have potential therapeutic value for the prevention and treatment of COPD.