Sohlh2 promotes pulmonary fibrosis via repression of p62/Keap1/Nrf2 mediated anti-oxidative signaling pathway

Abstract Disturbance in the redox balance of alveolar epithelial cells (AECs) was considered as a causal factor for pulmonary fibrosis. The regulatory mechanisms of redox hemostasis in the development of pulmonary fibrosis remain largely unknown. Using a type II AEC-specific Sohlh2 conditional knock-in (CKI) mouse model, we found that Sohlh2, a basic HLH transcription factor, accelerated age-related pulmonary fibrosis. High-fat diet (HFD) resulted in a tremendous increase in lung inflammation and fibrotic changes in the lung tissues of Sohlh2 CKI mice. Sohlh2 overexpression led to a significant rise of intracellular ROS and apoptosis in the lung, mouse primary AECIIs, and human A549 cells, which was attenuated by ROS inhibitor (NAC). Sohlh2 enhanced oxidative stress via repressing p62/Keap1/Nrf2 mediated anti-oxidative signaling pathway. p62, a direct target of Sohlh2, mediated Sohlh2 effects on ROS generation and apoptosis in A549 cells. Hence, our findings elucidate a pivotal mechanism underlying oxidative stress-induced pulmonary fibrosis, providing a framework for aging-related disorder interventions.