Background: Renal oxidative stress plays an important role in mediating kidney injury in diabetes. There is increasing evidences that recently discovered pro-oxidant enzyme, Nox5 plays a significant role in human diabetic nephropathy (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. We examined the role of Nox5 in human DN, in human renal cell populations and in a high fat fed rabbit model of kidney disease.
Methods: Protein expression of Nox5 and its localization in glomerular and tubular cells were examined 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 cells were exposed to high glucose, TGF-β and AngII. Cell morphology, gene and protein expression of markers of fibrosis and inflammation and putative signalling pathways and the level of ROS were assessed in these human renal cells. We also examined expression of pro-fibrotic gene in high fat fed rabbits by NGS and RT-PCR and renal injury by histochemistry.
Results: Expression of Nox5 was increased in both glomerular and tubular compartments of kidney biopsies obtained from diabetic individuals when compared to non-diabetic individuals. In addition, silencing of Nox5 in human renal cells 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 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 accelerates renal injury in diabetes and provide proof of principle for the development of a new renoprotective agent in diabetes.