Calpain-1 Up-Regulation Promotes Bleomycin-Induced Pulmonary Fibrosis by Activating Ferroptosis

Abstract

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive and fatal disease. Calpain-1 was shown to be an effective therapeutic target for vascular endothelial dysfunction and pulmonary hypertension. However, the role of calpain-1 in bleomycin (BLM)-induced IPF has not been defined. The aim of this study was to assess the targeting of calpain-1 by activating ferroptosis in BLM-treated knockout mice and MLE-12 cells. In this study, the role of calpain-1 in the regulation of IPF was investigated using a BLM-induced IPF mouse model. The results of our study showed that increased expression of calpain-1 was accompanied by increased fibrosis, lipid peroxidation, iron ion accumulation, and YAP levels and decreased levels of p-AMPK in BLM-induced IPF. MDL-28170 (Calpain-1 inhibition) treatment and calpain-1 knockdown alleviated ferroptosis and IPF induced by BLM. Overexpression of calpain-1 in MLE-12 cells further exacerbated iron accumulation and IPF. Mechanistically, lentivirus-mediated upregulation of calpain-1 inhibited AMPK activity and promoted the nuclear translocation of YAP, leading to high levels of ACSL4 and TFRC and triggering a ferroptosis response that ultimately exacerbated BLM-induced lung fibrosis. Calpain-1 inhibition reversed these results and to ameliorate BLM-induced IPF. In conclusion, these findings suggest that the calpain-1-ACSL4-TFRC-ferroptosis positive regulatory axis contributes to BLM-induced IPF, which indicates that calpain-1 has potential therapeutic value for the treatment of IPF.