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Alamandine attenuates hepatic fibrosis by regulating autophagy induced by NOX4-dependent ROS
Yun Huang1,2,3,4, Yang Li1,2,3, Anni Lou1
1Department of Emergency Medicine, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China.
Abstract:
Angiotensin II (Ang II) has been reported to aggravate hepatic fibrosis by inducing NADPH oxidase (NOX)-dependent oxidative stress. Alamandine (ALA) protects against fibrosis by counteracting Ang II via the MAS-related G-protein coupled (MrgD) receptor, though the effects of alamandine on hepatic fibrosis remain unknown. Autophagy activated by reactive oxygen species (ROS) is a novel mechanism of hepatic fibrosis. However, whether autophagy is involved in the regulation of Ang II-induced hepatic fibrosis still requires investigation. We explored the effect of alamandine on hepatic fibrosis via regulation of autophagy by redox balance modulation. In vivo, alamandine reduced CCl4-induced hepatic fibrosis, hydrogen peroxide (H2O2) content, protein levels of NOX4 and autophagy impairment. In vitro, Ang II treatment elevated NOX4 protein expression and ROS production along with up-regulation of the angiotensin converting enzyme (ACE)/Ang II/Ang II type 1 receptor (AT1R) axis. These changes resulted in the accumulation of impaired autophagosomes in hepatic stellate cells (HSCs). Treatment with NOX4 inhibitor VAS2870, ROS scavenger N-acetylcysteine (NAC), and NOX4 small interfering RNA (siRNA) inhibited Ang II-induced autophagy and collagen synthesis. Alamandine shifted the balance of renin-angiotensin system (RAS) toward the angiotensin converting enzyme 2 (ACE2)/alamandine/MrgD axis, and inhibited both Ang II-induced ROS and autophagy activation, leading to attenuation of HSCs migration or collagen synthesis. In summary, alamandine attenuated liver fibrosis by regulating autophagy induced by NOX4-dependent ROS.
Insights
Alamandine reduces liver fibrosis by modulating autophagy and oxidative stress. This study shows alamandine counteracts angiotensin II-induced damage by regulating NADPH oxidase-dependent reactive oxygen species and autophagy in hepatic stellate cells.
Area of Science:
- Hepatology
- Cellular Biology
- Pharmacology
Background:
- Angiotensin II (Ang II) exacerbates hepatic fibrosis through NADPH oxidase (NOX)-dependent oxidative stress.
- Reactive oxygen species (ROS)-activated autophagy is a newly identified mechanism in hepatic fibrosis.
- The role of autophagy in Ang II-induced hepatic fibrosis requires further investigation.
Purpose of the Study:
- To investigate the effect of alamandine on hepatic fibrosis.
- To explore alamandine's regulation of autophagy via redox balance modulation.
- To elucidate the underlying mechanisms involving the renin-angiotensin system (RAS).
Main Methods:
- In vivo studies using carbon tetrachloride (CCl4)-induced liver fibrosis model in mice.
- In vitro experiments using hepatic stellate cells (HSCs) treated with Ang II.
- Assessment of NOX4, ROS, autophagy markers, and collagen synthesis.
- Pharmacological inhibition of NOX4 and ROS scavenging (VAS2870, N-acetylcysteine) and NOX4 siRNA were employed.
Main Results:
- Alamandine treatment reduced CCl4-induced hepatic fibrosis, H2O2 content, NOX4 levels, and autophagy impairment in vivo.
- In vitro, Ang II increased NOX4, ROS, and impaired autophagosome accumulation in HSCs via the ACE/Ang II/AT1R axis.
- Inhibition of NOX4 or ROS attenuated Ang II-induced autophagy and collagen synthesis.
- Alamandine promoted the ACE2/alamandine/MrgD axis, inhibiting Ang II-induced ROS and autophagy, thereby reducing HSC migration and collagen synthesis.
Conclusions:
- Alamandine attenuates liver fibrosis by regulating NOX4-dependent ROS-induced autophagy.
- Alamandine counteracts Ang II effects by modulating the RAS balance towards the ACE2/alamandine/MrgD pathway.
- Targeting NOX4-dependent oxidative stress and autophagy presents a potential therapeutic strategy for hepatic fibrosis.
