Scavenging of reactive oxygen species by astaxanthin inhibits epithelial–mesenchymal transition in high glucose-stimulated mesothelial cells

BACKGROUND: High glucose concentrations influence the functional and structural development of the peritoneal membrane. We previously reported that the oral administration of astaxanthin (AST) suppressed peritoneal fibrosis (PF) as well as inhibited oxidative stress, inflammation, and epithelial–mesenchymal transition (EMT) of peritoneal mesothelial cells (PMCs) in a chlorhexidine-induced PF rat model. This suggests that oxidative stress induction of EMT is a key event during peritoneal damage. The present study evaluated the therapeutic effect of AST in suppressing EMT, in response to glucose-induced oxidative stress. METHODS: Temperature-sensitive mesothelial cells (TSMCs) were cultured in the presence or absence of AST and then treated with 140 mM glucose for 3 or 12 hours. Expression levels of TNF-α, TGF-β, and VEGF were determined at the mRNA and protein levels, and nuclear factor kappa B (NF-κB) activity was evaluated. We measured NO(2)(−)/NO(3)(−) concentrations in cellular supernatants and determined 8-hydroxy-2′-deoxyguanosine (8-OHdG) levels in mitochondrial and nuclear DNA. The expressions of E-cadherin and alpha-smooth muscle actin (α-SMA) were evaluated by double immunofluorescence and protein levels. RESULTS: High glucose concentrations induced overproduction of reactive oxidative species (ROS), increasing 8-OHdG mitochondrial DNA and cytokine levels. The NF-κB pathway was activated in response to high glucose concentrations, whereas de novo α-SMA expression was observed with decreased E-cadherin expression. AST treatment attenuated ROS production, inflammatory cytokine production, NF-κB activation, and EMT. CONCLUSION: The findings of the present study indicate that AST may have an anti-EMT effect due to anti-oxidative and anti-inflammatory activities by scavenging glucose-induced ROS from mitochondria in PMCs. AST may be an efficacious treatment for PF.