Huangkui capsule in combination with metformin ameliorates diabetic nephropathy via the Klotho/TGF-β1/p38MAPK signaling pathway

• Published in: Journal of ethnopharmacology 2021-12, Vol.281, p.113548-113548, Article 113548
• Main Authors: Gu, Li-yuan, Yun-Sun, Tang, Hai-tao, Xu, Zheng-xin
• Format: Article
• Language: English
• Subjects: Animals; Cell Line; Cell Proliferation - drug effects; Diabetes Mellitus, Experimental; Diabetic Nephropathies - chemically induced; Diabetic Nephropathies - drug therapy; Diabetic nephropathy; Diet, High-Fat - adverse effects; Dose-Response Relationship, Drug; Drugs, Chinese Herbal - administration & dosage; Drugs, Chinese Herbal - pharmacology; Gene Expression Regulation - drug effects; Glucose - administration & dosage; Glucose - adverse effects; Huangkui capsule; Humans; Hypoglycemic Agents - administration & dosage; Hypoglycemic Agents - pharmacology; Klotho; Klotho Proteins - genetics; Klotho Proteins - metabolism; Male; Metformin; Metformin - administration & dosage; Metformin - pharmacology; p38 Mitogen-Activated Protein Kinases - genetics; p38 Mitogen-Activated Protein Kinases - metabolism; Phytotherapy; Rats; Rats, Sprague-Dawley; Renal fibrosis; Transforming Growth Factor beta1 - genetics; Transforming Growth Factor beta1 - metabolism
• ISSN: 0378-8741; 1872-7573
• DOI: 10.1016/j.jep.2020.113548

Huangkui capsule (HKC), extracted from Abelmoschus manihot (L.) medic (AM), as a patent proprietary Chinese medicine on the market for approximately 20 years, has been clinically used to treat chronic glomerulonephritis. Renal fibrosis has been implicated in the onset and development of diabetic nephropathy (DN). However, the potential application of HKC for preventing DN has not been evaluated. This study was designed to investigate the efficacy and underlying mechanisms of HKC combined with metformin (MET), the first-line medication for treating type 2 diabetes, in the treatment of renal interstitial fibrosis. A rat model of diabetes-associated renal fibrosis was established by intraperitoneal injection of streptozotocin (STZ, 65 mg/kg) combined with a high-fat and high-glucose diet. The rats were randomly divided into five groups: normal control, DN, HKC (1.0 g/kg/day), MET (100 mg/kg/d), and HKC plus MET (1.0 g/kg/day + 100 mg/kg/d). Following drug administration for 8 weeks, we collected blood, urine, and kidney tissue for analysis. Biochemical markers and metabolic parameters were detected using commercial kits. Histopathological staining was performed to monitor morphological changes in the rat kidney. High-glucose-induced human kidney HK-2 cells were used to evaluate the renal protective effects of HKC combined with MET (100 μg/mL+10 mmol/L). MTT assay and acridine orange/ethidium bromide were used to examine cell proliferation inhibition rates and apoptosis. Immunofluorescence assay and Western blot analysis were performed to detect renal fibrosis-related proteins including Klotho, TGF-β1, and phosphorylated (p)-p38. Combination therapy (HKC plus MET) significantly improved the weight, reduced blood glucose (BG), blood urea nitrogen (BUN), total cholesterol (T-CHO), triglycerides (TG), low-density lipoprotein (LDL) and increased the level of high-density lipoprotein (HDL) of DN rats. Combination therapy also significantly reduced urine serum creatinine (SCR) and urine protein (UP) levels as well as reduced the degrees of renal tubule damage and glomerulopathy in DN rats. Combination therapy ameliorated renal fibrosis, as evidenced by reduced levels of alpha-smooth muscle actin and fibronectin and increased expression of E-cadherin in the kidneys. Moreover, HKC plus MET alleviated the degree of DN in part via the Klotho/TGF-β1/p38MAPK signaling pathway. In vitro experiments showed that combination therapy significantly inhibited cell proliferation