JAY JHA1, AOZHI DAI1, MARK COOPER1, CHRIS R. KENNEDY2, KARIN JANDELEIT-DAHM1
1Department Of Diabetes, Monash University, Melbourne, Australia, 2Department of Medicine, Ottawa Hospital Research Institute, Ottawa, Ottawa, Canada
Background: Reactive oxygen species (ROS) plays a critical role in the pathogenesis of DKD. Pro-oxidant enzymes Nox4 and Nox5 are shown to be involved in the pathogenesis of DKD. We examined the role of Nox5 independent of Nox4 expression in DKD using Nox5 transgenic mouse model.
Methods: In vivo, we examined the effect of Nox5 expression in Nox4KO mice as well as in GKT137831 (a renal Nox4 inhibitor) treated mice in the presence or absence of streptozotocin induced diabetes. In vitro, human renal cells including mesangial cell and podocytes were knockdown for Nox4 and Nox5 and were exposed to high glucose. Markers of fibrosis and inflammation as well as the level of ROS were assessed in vitro. We also developed high fat feeding and alloxan induced diabetic rabbit models of DKD as well as generated a Nox5KO rabbit to elucidate the role of Nox5 in DKD.
Results: Silencing of Nox5 attenuated high glucose induced gene expression of markers of fibrosis and inflammation as well as putative elements via reduction in ROS formation. Our data also suggest that Nox5 is upstream of Nox4 and that Nox5 inhibition also downregulates Nox4, but not vice versa. In vivo, overexpression of Nox5 in both Nox4 KO and GKT137831 treated mice demonstrated a 30-40% increase in albuminuria, renal fibrosis and inflammation in association with 2-fold increase expression of renal early growth response 1 (Egr1) and enhanced ROS production in comparison to diabetic mice not expressing Nox5.
Conclusions: These findings provide evidence that Nox5 plays a superior pathogenic role in DKD in comparison to Nox4. Therefore, targeting Nox5 may represent a better approach to treat and prevent DKD in human.
Dr Jha is an early career NHMRC research fellow, who is already highly recognised in the field of diabetes and kidney disease particularly as it relates to oxidative stress (Expertscape). Dr Jha has the skills and knowledge base with a strong track record in experimental diabetic complications protocols as well as expertise in molecular biology, renal phenotyping, data analysis and supervision of complex preclinical studies.