• Ying Meng, Ting Li, Gao-Su Zhou, Yan Chen, Chang-Hui Yu, Miao-Xia Pang, Wei Li, Yang Li, Wen-Yong Zhang, and Xu Li.
• 1 Department of Respiratory Diseases, Nanfang Hospital, the Southern Medical University , Guangzhou, China .
• Antioxid. Redox Signal. 2015 Jan 20;22(3):241-58.

UnlabelledReactive oxygen species (ROS) generated by NADPH oxidase-4 (NOX4) have been shown to initiate lung fibrosis. The migration of lung fibroblasts to the injured area is a crucial early step in lung fibrosis. The angiotensin-converting enzyme 2 (ACE2)/angiotensin (1-7) [Ang(1-7)]/Mas axis, which counteracts the ACE/angiotensin II (AngII)/angiotensin II type 1 receptor (AT1R) axis, has been shown to attenuate pulmonary fibrosis. Nevertheless, the exact molecular mechanism remains unclear.AimsTo investigate the different effects of the two axes of the renin-angiotensin system (RAS) on lung fibroblast migration and extracellular matrix accumulation by regulating the NOX4-derived ROS-mediated RhoA/Rho kinase (Rock) pathway.ResultsIn vitro, AngII significantly increased the NOX4 level and ROS production in lung fibroblasts, which stimulated cell migration and α-collagen I synthesis through the RhoA/Rock pathway. These effects were attenuated by N-acetylcysteine (NAC), diphenylene iodonium, and NOX4 RNA interference. Moreover, Ang(1-7) and lentivirus-mediated ACE2 (lentiACE2) suppressed AngII-induced migration and α-collagen I synthesis by inhibiting the NOX4-derived ROS-mediated RhoA/Rock pathway. However, Ang(1-7) alone exerted analogous effects on AngII. In vivo, constant infusion with Ang(1-7) or intratracheal instillation with lenti-ACE2 shifted the RAS balance toward the ACE2/Ang(1-7)/Mas axis, alleviated bleomycin-induced lung fibrosis, and inhibited the RhoA/Rock pathway by reducing NOX4-derived ROS.InnovationThis study suggests that the ACE2/Ang(1-7)/Mas axis may be targeted by novel pharmacological antioxidant strategies to treat lung fibrosis induced by AngII-mediated ROS.ConclusionThe ACE2/Ang(1-7)/Mas axis protects against lung fibroblast migration and lung fibrosis by inhibiting the NOX4-derived ROS-mediated RhoA/Rock pathway.

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