NOX4-Derived ROS Promotes Collagen I Deposition in Bronchial Smooth Muscle Cells by Activating Noncanonical p38MAPK/Akt-Mediated TGF- β Signaling

摘要

Background . Airway smooth muscle (ASM) remodeling is a hallmark in chronic obstructive pulmonary disease (COPD). NADPH oxidase 4- (NOX4-) mediated reactive oxygen species (ROS) production plays a crucial role in cell differentiation and extracellular matrix (ECM) synthesis in ASM remodeling. However, the precise mechanisms underpinning its pathogenic roles remain elusive. Methods . The expression of NOX4 and TGF- β 1 in the airway of the lung was measured in COPD patients and the control group. Cigarette smoke- (CS-) induced emphysema mice were generated, and the alteration of α -SMA, NOX4, TGF- β 1 , and collagen I was accessed. The changes of the expression of ECM markers, NOX4, components of TGF- β /Smad, and MAPK/Akt signaling in human bronchial smooth muscle cells (HBSMCs) were ascertained for delineating mechanisms of NOX4-mediated ROS production on cell differentiation and remodeling in human ASM cells. Results . An increased abundance of NOX4 and TGF- β 1 proteins in the epithelial cells and ASM of lung was observed in COPD patients compared with the control group. Additionally, an increased abundance expression of NOX4 and α -SMA was observed in the lungs of the CS-induced emphysema mouse model. TGF- β 1 displayed abilities to increase the oxidative burden and collagen I production, along with enhanced phosphorylation of ERK, p38MAPK, and p-Akt473 in HBSMCs. These effects of TGF- β 1 could be inhibited by the ROS scavenger N-acetylcysteine (NAC), siRNA-mediated knockdown of Smad3 and NOX4, and pharmacological inhibitors SB203580 (p38MAPK inhibitor) and LY294002 (Akt inhibitor). Conclusions . NOX4-mediated ROS production alters TGF- β 1 -induced cell differentiation and collagen I protein synthesis in HBSMCs in part through the p38MAPK/Akt signaling pathway in a Smad-dependent manner.