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OBJECTIVE: Diabetic nephropathy (DN) is the leading cause of end-stage renal disease in diabetic patients. Astragalus polysaccharide (APS) is a natural active ingredient in Astragalus membranaceus with anti-hypertensive and anti-oxidative properties. This study aimed to explore the protective roles of APS and its underlying mechanisms in DN. METHODS: After the establishment of a rat model of DN by a high-fat diet and treatment with 30 mg/kg streptozotocin (STZ), the effects of 100 mg/kg APS on the levels of serum creatinine, blood urea nitrogen, blood glucose, and urinary albumin-to-creatinine ratio were measured. Histopathological alterations in renal tissues, renal cell apoptosis, renal inflammation, and oxidative stress were examined. The impacts of 0-200 µg/mL APS on the viability and apoptosis in high glucose (HG)-stimulated podocytes were measured by Cell Counting Kit-8 assays and flow cytometry, respectively. The expression of genes was tested by immunoblotting, quantitative real-time PCR, and immunofluorescence staining. RESULTS: APS enhanced the expression of podocin and nephrin, increased viability, and reduced apoptosis in HG-induced podocytes. APS treatment abrogated high glucose-mediate suppression of autophagy in podocytes by activating the Sirt1/FoxO1 pathway. The Sirt1 inhibitor EX-527 eliminated the ameliorative effects of APS on renal dysfunction and renal tissue damage, as well as the inhibitory effects of APS on oxidative stress, inflammation, and apoptosis in DN rats. Moreover, EX-527 inhibited APS-induced autophagy activation in DN rats. CONCLUSION: APS mitigated DN under hyperglycemic conditions by activating the Sirt1/FoxO1 autophagy pathway, suggesting that APS is a promising agent for DN treatment.
RESUMEN
AIM: This study was designed to use in vivo and in vitro approaches to evaluate puerarin in diabetes-induced renal injury. MATERIALS AND METHODS: SD rats were divided into NC (normal control), Model (diabetic induced renal injury model), SP-L (model rats treated with low-dose standard puerarin), SP-M (model rats treated with middle-dose standard puerarin), and SP-H (model rats treated with high-dose standard puerarin) groups. We evaluated fasting blood-glucose (FBG), urinary albumin/creatinine ratio (UACR), body weight, and kidney index (KI) in the different groups. TNF-α, IL-1ß, and IL-6 concentrations were measured using Elisa assays. HE staining and TUNEL assays were used to evaluate pathology and apoptosis in kidney tissues, respectively. Relative gene and protein expression was measured using RT-qPCR and Western blot assays. Apoptosis was measured using flow cytometry. The correlation between miRNA-145-5p and TLR4 was assessed using dual-luciferase reporter gene assays. RESULTS: The pathology and apoptosis cell number were deteriorate in Model group; TNF-α, IL-1ß and IL-6 concentrations, FGB, UACR and KI were increased and body weight was depressed; meanwhile, relative gene and proteins expressions (miRNA-145-5p, TLR4, MyD88 and NF-κB p65) were significantly different in Model group in vivo and vitro study compared with NC group. SP treatment significantly improved the pathology and apoptosis levels in the tissues, as well as TNF-α, IL-1ß and IL-6 concentrations, FGB, UACR, body weight, and KI. In vitro cell studies revealed that SP could prevent renal injury induced by diabetes through the miRNA-145-5p/TLR4 axis. CONCLUSION: SP prevents diabetes-induced renal damage via miRNA-145-5p overexpression and reduces TLR4/MyD88/NF-κB (p65) pathway activation in vitro and in vivo.
