Managing diabetic nephropathy: recent studies

Dihydromyricetin promotes autophagy and attenuates renal interstitial fibrosis by regulating miR-155-5p/PTEN signaling in diabetic nephropathy

Diabetic nephropathy (DN) is the most common complication of diabetes and is prone to kidney failure. Dihydromyricetin (DHM) has been reported to have a variety of pharmacological activities. This study aims to explore the effect of DHM on DN and the underlying molecular mechanism. An in vivo DN rat model was established. The degree of renal interstitial fibrosis (RIF) was detected by hematoxylin-eosin (HE) staining, Masson's trichrome staining, and immunohistochemistry (IHC). In vitro, NRK-52E cells were divided into four groups: normal glucose (NG), high glucose (HG), HG+DHM, and HG+rapamycin (autophagy inhibitor). The levels of autophagy- and fibrosis-related proteins were analyzed by western blotting. The expression of miR-155-5p and phosphatase and tensin homolog deleted on chromosome ten (PTEN) and their relationship were assessed by quantitative reverse transcription (qRT)-PCR and dual luciferase reporter gene assay. Our results showed that RIF was increased in DN rat model and in HG-induced NRK-52E cells. DHM treatment attenuated the increased RIF and also increased autophagy. MiR-155-5p expression was increased, while PTEN expression was decreased in DN rat and cell model, and DHM reversed both effects. Dual luciferase assay showed that PTEN was the target gene of miR-155-5p. DHM inhibited HG-induced fibrosis and promoted autophagy by inhibiting miR-155-5p expression in NRK-52E cells. In addition, DHM promoted autophagy by inhibiting the PI3K/AKT/mTOR signaling pathway. In conclusion, DHM promotes autophagy and attenuates RIF by regulating the miR-155-5p/PTEN signaling and PI3K/AKT/mTOR signaling pathway in DN.

Oleanolic acid attenuated diabetic mesangial cell injury by activation of autophagy via miRNA-142-5p/PTEN signaling

Oleanolic acid (OA), a potential drug for diabetic nephropathy (DN) treatment was found to downregulate the expression of microRNA (miR). The research aimed to investigate the effect of OA on autophagy mediated through miR-142-5p targeted PTEN signal. NRK-52E cells were cultured under normal or high glucose condition. DN model were induced by intravenous injection with streptozotocin (55 mg/kg). Renal fibrosis mice were detected by hematoxylin and eosin (HE) staining, Masson staining and immunohistochemistry assay. TargetScan and dual-luciferase reporter assay system was used to detect the target of miR-142-5p. Expression levels of microRNA and proteins were analyzed by real-time PCR and western blotting. Autophagy was decreased in the progression of renal fibrosis in diabetic nephropathy mice (in vivo) and in high glucose-induced NRK-52E cells (rat kidney epithelial cells) (in vitro) as the expression ofLC-3I and LC-3II (indicators of autophagy) were decreased mice MiR-142-5p was unregulated and PTEN was down-regulated in kidney mice and high glucose-induced NRK-52E cells. Targetscan prediction revealed that PTEN was a target of miR-142-5p. OA restricted HG-induced NRK-52E cell fibrosis through inhibition of miR-142-5p to promote PTEN expression and autophagy levels. To sum up, the research indicated that OA promoted autophagy through inhibition of PI3K/AKT/mTOR pathway. OA alleviated diabetic renal fibrosis by increasing autophagy through regulation of miR-142-5p/PTEN via PI3K/AKT/mTOR pathway in NRK-52E cells.