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The kidney is a typical organ undergoing age and injury. Hyperoside is reported to be useful for preventing aging induced by D-galactose (D-gal). However, therapeutic mechanisms remain unclear. We thereby aimed to verify whether hyperoside, compared to vitamin E (VE), could alleviate renal aging and injury by regulating autophagic activity and its related signaling pathways. In vivo, rats were administered with either hyperoside or VE after renal aging modeling induced by D-gal. Changes in renal aging and injury markers, autophagic activity and AMPK-ULK1 signaling pathway in the kidneys were analysed. In vitro, the NRK-52E cells exposed to D-gal were used to investigate regulative actions of hyperoside and VE on cell viability, renal tubular cellular aging markers, autophagic activity and its related signaling pathways by histomorphometry, immunohistochemistry, immunofluorescence, lentiviral transfection and Western blot. Aging and injury in the kidneys and renal tubular cells induced by D-gal were ameliorated by hyperoside and VE. Hyperoside and VE inhibited autophagic activity through mTOR-independent and AMPK-ULK1 signaling pathways. Hyperoside, as a component of phytomedicine similar to VE, attenuated renal aging and injury induced by D-gal via inhibiting AMPK-ULK1-mediated autophagy. This study provides the first evidence that hyperoside contributes to the prevention of age-associated renal injury.

Huangkui capsule (HKC), a Chinese modern patent medicine extracted from Abelmoschus manihot (L.) medic, has been widely applied to clinical therapy in the early diabetic nephropathy (DN) patients. However, it remains elusive whether HKC can ameliorate the inchoate glomerular injuries in hyperglycemia. Recently the activation of phosphatidylinositol-3-kinase (PI3K)/serine-threonine kinase (Akt)/mammalian target of rapamycin (mTOR) signaling and its downstream regulator, 70-kDa ribosomal protein S6 kinase (p70S6K), play important roles in the early glomerular pathological changes of DN including glomerular hypertrophy, glomerular basement membrane (GBM) thickening and mild mesangial expansion. This study thereby aimed to clarify therapeutic effects of HKC during the initial phase of DN and its underlying mechanisms. Fifteen rats were randomly divided into 3 groups: the normal group, the model group and the HKC group. The early DN model rats were induced by unilateral nephrectomy combined with intraperitoneal injection of streptozotocin, and administered with either HKC suspension or vehicle after modeling and for a period of 4 weeks. Changes in the incipient glomerular lesions-related parameters in urine and blood were analyzed. Kidneys were isolated for histomorphometry, immunohistochemistry, immunofluorescence and Western blotting (WB) at sacrifice. In vitro, murine mesangial cells (MCs) were used to investigate inhibitory actions of hyperoside (HYP), a bioactive component of HKC, on cellular hypertrophy-associated signaling pathway by WB, compared with rapamycin (RAP). For the early DN model rats, HKC ameliorated micro-urinary albumin, body weight and serum albumin, but had no significant effects on renal function and liver enzymes; HKC improved renal shape, kidney weight and kidney hypertrophy index; HKC attenuated glomerular hypertrophy, GBM thickening and mild mesangial expansion; HKC inhibited the phosphorylation of Akt, mTOR and p70S6K, and the protein over-expression of transforming growth factor-β1 in kidneys. In vitro, the phosphorylation of PI3K, Akt, mTOR and p70S6K in MCs induced by high-glucose was abrogated by treatment of HYP or RAP. On the whole, this study further demonstrated HKC safely and efficiently alleviates the early glomerular pathological changes of DN, likely by inhibiting Akt/mTOR/p70S6K signaling activity in vivo and in vitro, and provided the first evidence that HKC directly contributes to the prevention of the early DN.

Rhubarb and its bioactive component rhein are frequently used for the treatment of chronic kidney diseases (CKD) in eastern Asia countries. However, the potential therapeutic mechanism remains unclear. Autophagy plays an important role in CKD. However, there were some important related issues that remained unresolved in the role of autophagy in CKD and treatment by rhubarb and rhein. We designed a number of experiments to examine whether rhubarb may reduce renal fibrosis and autophagy in rats with adenine (Ade)-induced renal tubular injury, and whether rhein could affect autophagic pathways in rat renal tubular cells. We found that, autophagic activation accompanied with renal fibrosis in rats with Ade-induced renal tubular injury, and both autophagy and renal fibrosis were attenuated by rhubarb. In addition, we observed that rhein could inhibit autophagy through regulating the key molecules in the AMPK-dependent mTOR signaling pathways, as well as the Erk and p38 MAPKs signaling pathways. These findings may partly explain the therapeutic mechanisms of rhubarb and rhein in treating CKD patients in clinic, and further suggest that targeting autophagy and related signaling pathways may provide new strategies for the treatment of renal fibrosis in CKD.

Multi-glycoside of Tripterygium wilfordii Hook. f. (GTW) has been proven to be clinically effective in relieving microinflammation in patients with early diabetic nephropathy (DN). However, the therapeutic mechanisms involved in vivo remain unclear. In the process of early DN, microinflammation and activation of p38 mitogen-activated protein kinase (MAPK) and canonical nuclear factor (NF)-κB signaling pathways are the important mechanisms by which hyperglycemia contributes to glomerulosclerosis (GS). Therefore, this study aimed to examine the ameliorative effects of GTW on GS, and then to clarify its anti-microinflammatory mechanisms by inhibiting p38 MAPK and NF-κB signaling activities in the kidney. All rats were divided into 4 groups: the sham group, the sham + GTW group, the vehicle group and the GTW group. The suitable dose of GTW and vehicle were daily administered for 8 weeks after the induction of DN by unilateral nephrectomy combined with intraperitoneal injections of streptozotocin (STZ). The general status of the rats, biochemical parameters, renal histological changes and macrophages in glomeruli, as well as expression of the key proteins in the p38 MAPK and canonical NF-κB signaling pathways and inflammatory cytokines including tumor necrosis factor (TNF)-α, interleukin (IL)-1β and transforming growth factor (TGF)-β1 in the kidney were examined, respectively. The results revealed that, GTW improved the general cond ition and biochemical parameters of the rats, but did not lower blood glucose; GTW attenuated GS and suppressed glomerular microinflammation including the infiltration of ED1+ cells in glomeruli and the protein overexpression of TNF-α, IL-1β and TGF-β1 in the kidney; GTW inhibited the protein overexpression of key signaling molecules of p38 MAPK and canonical NF-κB pathways in the kidney including phosphorylated p38 MAPK, phosphorylated inhibitor protein IκB and NF-κB (p65). On the whole, we expounded that GTW, as a natural regulator in vivo, alleviates GS without affecting hyperglycemia, by exerting anti-microinflammatory effects, including reducing macrophage infiltration in glomeruli, suppressing TNF-α, IL-1β and TGF-β1 overexpression in the kidney and inhibiting p38 MAPK and NF-κB signaling activities.