J C JHA1,2, M T COUGHLAN1,2, D A. POWER3, A SKENE4, E I. EKINCI5, M E. COOPER1,2, C R. KENNEDY6, K JANDELEIT-DAHM1,2.
1Department of Diabetes, Central Clinical School, Monash University, Melbourne, Australia; 2Baker IDI Heart and Diabetes Institute, Melbourne, Australia; 3Department of Nephrology and Institute of Breathing and Sleep, Austin Health, Heidelberg, Australia, 4Department of Anatomical Pathology, Austin Health, Heidelberg, Australia; 5Endocrine Centre, Austin Health, Repatriation Campus, Heidelberg, Australia and 6Department of Medicine, Ottawa Hospital Research Institute, Ottawa, Canada.
Aim: We examined the role of Nox5 in human diabetic nephropathy (DN), in human renal cell populations and in a high fat fed rabbit model of kidney disease.
Background: Oxidative stress plays an important role in mediating kidney injury in diabetes. Evidences suggest that pro-oxidant enzyme, Nox5 plays a significant role in human DN. Nox5 is present in humans and rabbits but not in mice or rats. Thus, there is a paucity of information about Nox5 in conventional animal models of DN.
Methods: Protein expression of Nox5 was examined by immunostaining in human kidney biopsies obtained from non-diabetic and diabetic individuals. In vitro, Nox5 was silenced in human mesangial cells, podocytes and in proximal tubules and were exposed to high glucose, TGF-β and AngII. Cell morphology, gene and protein expression of markers of fibrosis and inflammation and the level of ROS were assessed. We also examined expression of pro-fibrotic gene in high fat fed rabbits by next generation sequencing (NGS) and renal injury by histochemistry.
Results: Expression of Nox5 was increased in both glomerular and tubular compartments of kidney biopsies obtained from diabetic versus non-diabetic individuals. Silencing of Nox5 resulted in reduced ROS production and decreased expression of pro-fibrotic and pro-inflammatory markers as well as putative elements that are implicated in DN. Moreover, increased expression of Nox5 in high fat fed rabbits versus normal diet fed rabbits was associated with increased expression of fibronectin, CTGF, collagen IV and VCAM-1 and increased mesangial expansion in the kidney.
Conclusions: Collectively, these findings suggest that Nox5 derived ROS accelerates renal injury in diabetes and provide proof of principle for the development of a new renoprotective agent in diabetes.