Treatment of db/db diabetic mice with triptolide: a novel therapy for diabetic nephropathy

Background. Current research on the progression of diabetic nephropathy (DN) suggests many important factors; metabolic disturbance, haemodynamic abnormity, chronic inflammation, oxidative stress, innate immune system activation and podocyte lesion. Triptolide, which is active diterpene purified from the traditional Chinese medicine Tripterygium wilfordii Hook F (TwHF), has anti-inflammatory, anti-oxidative, immunosuppressive and podocyte-protective effects. Herein, we investigated the therapeutic effects of triptolide on DN in db/db diabetic mice and studied the potential mechanisms. Methods. db/db mice with DN were administrated with triptolide or valsartan. After 4, 8 and 12 weeks of treatment, 24-h urine albumin level, blood biochemical parameters and body weight were measured. Glomerulus area, glomerulus volume to Bowman's capsule volume ratio, podocyte changes and inflammatory and oxidative stress markers were quantitatively determined to evaluate renal lesions. Results. The albuminuria in db/db diabetic mice was markedly attenuated after triptolide treatment, accompanied with alleviated glomerular hypertrophy and podocyte injury. In addition, the inflammation and oxidative stress in the kidneys were also attenuated, accompanied with improved hyperlipidaemia and obesity. The efficacy increased with the prolonging of triptolide treatment, and the efficacy in high-dose triptolide group was superior to that in the low-dose group. The effect of triptolide on glomerular hypertrophy was similar to valsartan, but the effects of triptolide on renal inflammation and oxidative stress were more profound than those of valsartan. Conclusions. Triptolide can dramatically attenuate albuminuria and renal lesion accompanied with dyslipidaemia and obesity in db/db diabetic mice. It is a new drug that exerts comprehensive protective effects on preventing DN progression.