Amelioration of Early Markers of Diabetic Nephropathy by Linagliptin in Fructose-Streptozotocin-Induced Type 2 Diabetic Rats

Abstract

Background: Early prediction and clinical intervention are extremely important in order to delay or hinder diabetic nephropathy (DN) progression.

Objectives: This study aimed to detect early signs of DN and study the potential ameliorating effect of the dipeptidyl peptidase-4 inhibitor, linagliptin, on some early markers for DN in fructose-streptozotocin (Fr-STZ)-induced diabetic rats.

Method: Fr-STZ rats were treated with either linagliptin (3 mg/kg p.o. daily), metformin (350 mg/kg p.o. daily), or their combination for 6 weeks.

Results: Fr-STZ DN rats exhibited obvious tubular renal damage and glomerular podocyte injury as confirmed by renal kidney -injury molecule-1 (KIM-1), neutrophil gelatinase-associated lipocalin (NGAL), and vanin-1 mRNA, as well as urinary N-acetyl-β-D-glucosaminidase elevation and nephrin mRNA suppression, associated with the appearance of marked renal interstitial fibrosis and glomerulosclerosis despite the absence of microalbuminuria. Initiation of oxidative, inflammatory, fibrotic, and apoptotic reactions was evident in the settings of renal hyperglycemia. Linagliptin significantly modulated the aforementioned renal tubular injury makers and restored glomerular nephrin expression as well as reversed renal histopathological alterations. Oxidative, inflammatory, fibrotic and apoptotic processes were also alleviated.

Conclusions: This study suggests that linagliptin exerts renoprotection against early features of DN in rats probably by inhibition of high glucose-induced renal tubular and glomerular injury thereby hampering KIM-1 and NGAL as well as vanin-1 associated with renal inflammation, fibrosis and oxidative stress.

Keywords: Diabetic nephropathy; Fructose-streptozotocin; Kidney injury molecule-1; Linagliptin; Neutrophil gelatinase-associated lipocalin; Vanin-1.