Deletion of p47 phox attenuates the progression of diabetic nephropathy and reduces the severity of diabetes in the Akita mouse

Abstract

Aims/hypothesis: Reactive oxygen species (ROS) contribute to diabetes-induced glomerular injury and endoplasmic reticulum (ER) stress-induced beta cell dysfunction, but the source of ROS has not been fully elucidated. Our aim was to determine whether p47 phox -dependent activation of NADPH oxidase is responsible for hyperglycaemia-induced glomerular injury in the Akita mouse, a model of type 1 diabetes mellitus resulting from ER stress-induced beta cell dysfunction. Methods: We examined the effect of deleting p47 phox (also known as Ncf1), the gene for the NADPH oxidase subunit, on diabetic nephropathy in the Akita mouse (Ins2 WT/C96Y) by studying four groups of mice: (1) non-diabetic mice (Ins2 WT/WT /p47 phox+/+ ); (2) non-diabetic p47 phox -null mice (Ins2 WT/WT /p47 phox-/- ); (3) diabetic mice: (Ins2 WT/C96Y /p47 phox+/+ ); and (4) diabetic p47 phox -null mice (Ins2 WT/C96Y /p47 phox-/- ). We measured the urinary albumin excretion rate, oxidative stress, mesangial matrix expansion, and plasma and pancreatic insulin concentrations in 16-week-old mice; we also measured glucose tolerance and insulin sensitivity, islet and glomerular NADPH oxidase activity and subunit expression, and pro-fibrotic gene expression in 8-week-old mice. In addition, we measured NADPH oxidase activity, subunit expression and pro-fibrotic gene expression in high glucose-treated murine mesangial cells. Results: Deletion of p47 phox reduced kidney hypertrophy, oxidative stress and mesangial matrix expansion, and also reduced hyperglycaemia by increasing pancreatic and circulating insulin concentrations. p47 phox-/- mice exhibited improved glucose tolerance, but modestly decreased insulin sensitivity. Deletion of p47 phox attenuated high glucose-induced activation of NADPH oxidase and pro-fibrotic gene expression in glomeruli and mesangial cells. Conclusions/interpretation: Deletion of p47 phox attenuates diabetes-induced glomerular injury and beta cell dysfunction in the Akita mouse. © 2012 Springer-Verlag.