The Study Of Renal Protective Effects And Mechanisms Of Dihydroquercetin On Diabetic Nephropathy

【Background】Diabetic nephropathy(DN),one of the leading causes of end-stage renal disease,is acknowledged as an independent risk factor for cardiovascular disease,and is lack of positive and effective medications.Dihydroquercetin(DHQ),an important dihydroflavone botanical compound,exerts significant anti-oxidation,anti-inflammatory,and antifibrotic properties,and its effects on DN are not investigated yet.【Objective】We aimed to explore the renal-protective effects and mechanisms of DHQ on DN in vivo and in vitro.【Methods】DN rats were induced by high-fat diet/ streptozotocin.The levels of urine microalbumin of 24 h and fasting serum insulin were measured by ELISA kits.Major biochemical indexes were measured including serum levels of creatinine,fasting serum glucose,low-density lipoprotein cholesterol and total cholesterol.Renal histologic sections were stained with hematoxylin-eosin and periodic acid-Schiff.Immunohistochemical staining was conducted to evaluate the expression of IL-1β in kidney.The rat mesangial cells HBZY-1 and human proximal tubular epithelial cells HK2 were exposed to high glucose to establish the cell model of DN.The cell proliferation was assessed by MTT assay.Reactive oxygen species(ROS)generation was detected by DCFH-DA assay and laser scanning confocal microscope.Proteins examined by Western-blot included NLRP3,Cleaved Caspase-1,IL-1β,Fibronectin and Collagen Ⅳ.【Results】1.High-fat diet/streptozotocin-induced DN rats showed significantly elevated levels of 24-hour urine microalbumin,serum creatinine,fasting serum glucose,fasting insulin,low-density lipoprotein cholesterol and total cholesterol levels,and decreased Insulin sensitivity index,renal histopathological impair including glomerular mesangial cell proliferation and mesangial matrix expansion,and overexpressed glomerular IL-1β.After treatment of 12 weeks with high dose of DHQ(100 mg/kg/day),levels of 24 h urine microalbumin,serum creatinine,low-density lipoprotein cholesterol and total cholesterolwere significantly decreased in DN rats,and renal histopathological lesions were alleviated including decreased mesangial cell proliferation and mesangial matrix expansion,and decreased expression of glomerular IL-1β.Besides,fasting serum insulin levels and insulin sensitivity index were not significantly changed.2.After exposure to high concentration of glucose,HBZY-1 cells and HK2 cells manifested cell proliferation,increasing intracellular and mitochondrial ROS production,activated NLRP3 inflammasome-related proteins including NLRP3,Cleaved Caspase-1and IL-1β,and overexpressed renal fibrosis-related proteins of extracellular matrix including Fibronectin and Collagen Ⅳ.After DHQ treatment,cell proliferation was suppressed significantly,and the intracellular and mitochondrial ROS production was decreased.The overexpression of proteins including NLRP3,Cleaved Caspase-1,IL-1β,Fibronectin and Collagen Ⅳ were down-regulated significantly.【Conclusion】The results revealed that DHQ possesses renal protective effects including attenuating urine microalbumin excretion,and lipid metabolism disorders,and mitigating renal histopathological lesions on DN,and the possible renal protective mechanisms were suppressing cell proliferation,ROS production,NLRP3 inflammasome and renal fibrosis.