Triptolide markedly attenuates albuminuria and podocyte injury in an animal model of diabetic nephropathy

Abstract

Triptolide is a major active component of Tripterygium wilfordii Hook F, which exerts marked immunosuppressive, anti-inflammatory and podocyte-protective effects. In this study, the ability of triptolide to inhibit inflammation and attenuate podocyte injury was examined in a rat model of diabetic nephropathy (DN). Type II diabetic rats with DN were treated with triptolide at a dose of 100 μg.kg ⁻¹.day ⁻¹. Following 8 weeks of triptolide treatment, the urine albumin level, kidney weight/body weight and the number of cells positive for ED-1 (a marker for rat mononuclear macrophages) in the kidney were assessed. The effects of triptolide on podocyte injury and chronic inflammation were analyzed using quantitative polymerase chain reaction (qPCR), western blotting and immunohistochemistry. Following triptolide treatment, the albuminuria in the type II diabetic rats was significantly reduced. Furthermore, the glomerular hypertrophy and foot process effacement were improved, and there was a recovery of the slit diaphragm associated with nephrin and podocin expression. The inflammation in the kidneys was also attenuated. Furthermore, triptolide significantly reduced the expression of transforming growth factor-β1 and osteopontin, and the infiltration of ED-1-positive cells into the kidney. The results demonstrated that triptolide markedly attenuated albuminuria and podocyte injury in the rat model of DN, which may have been correlated with the inhibition of inflammation and macrophage infiltration in the kidneys.