[Notoginsenoside R_1 interferes with renal oxidative stress and Nrf2/HO-1 signaling pathway to alleviate kidney injury in mice with IgA nephropathy and its mechanism].

The purpose of this study was to investigate the effect of notoginsenoside R_1(NGR_1) on alleviating kidney injury by regulating renal oxidative stress and the Nrf2/HO-1 signaling pathway in mice with IgA nephropathy(IgAN) and its mechanism. The mouse model of IgAN was established using a variety of techniques, including continuous bovine serum albumin(BSA) gavage, subcutaneous injections of carbon tetrachloride(CCl_4) castor oil, and tail vein injections of lipopolysaccharide(LPS). After successful modeling, mice with IgAN were randomly separated into a model group, low, medium, and high-dose NGR_1 groups, and a losartan group, and C57BL6 mice were utilized as normal controls. The model and normal groups were given phosphate buffered saline(PBS) by gavage, the NGR_1 groups were given varying dosages of NGR_1 by gavage, and the losartan group was given losartan by gavage for 4 weeks. The 24-hour urine of mice was collected after the last administration, and serum and kidney tissues of mice were taken at the end of the animal experiment. Then urine red blood cell count(URBCC), 24-hour urine protein(24 h protein), serum creatinine(Scr), and blood urea nitrogen(BUN) levels were measured. The enzyme-linked immunosorbent assay(ELISA) was used to detect the levels of galactose-deficient IgA1(Gd-IgA1), kidney injury molecule 1(Kim-1), and neutropil gelatinase-associated lipocalin(NGAL) in the mouse serum. The assay kits were used to detect the levels of malondialdehyde(MDA) and superoxide dismutase(SOD), and immunofluorescence(IF) was used to detect the expression level of glutathione peroxidase 4(GPX4) in the mesangial region. Western blot was used to detect the protein expression of nuclear transcription factor E2 related factor 2(Nrf2)/heme oxygenase 1(HO-1) signaling pathway in the renal tissue. Hematoxylin-eosin(HE) staining was used to observe pathological alterations in the glomerulus of mice. The results revealed that, as compared with the model group, the serum Gd-IgA1 level, URBCC, 24 h protein level, renal damage markers(Kim-1 and NGAL) in the high-dose NGR_1 group decreased obviously and renal function indicators(BUN, Scr) improved significantly. The activity of SOD activity and expression level of GPX4 increased significantly in the high-dose NGR_1 group, whereas the expression level of MDA reduced and protein expression levels of Nrf2 and HO-1 increased. Simultaneously, HE staining of the renal tissue indicated that glomerular damage was greatly decreased in the high-dose NGR_1 group. In conclusion, this study has clarified that NGR_1 may alleviate the kidney injury of mice with IgAN by activating the Nrf2/HO-1 signaling pathway, improving antioxidant capacity, and reducing the level of renal oxidative stress.

[Icariin improves renal interstitial fibrosis in a rat model of chronic renal failure by regulating mitochondrial dynamics].

This study aims to explore the effect of icariin(ICA) on mitochondrial dynamics in a rat model of chronic renal failure(CRF) and to investigate the molecular mechanism of ICA against renal interstitial fibrosis(RIF). CRF was induced in male Sprague-Dawley(SD) rats with 5/6(ablation and infarction, A/I) surgery(right kidney ablation and 2/3 infarction of the left kidney). Four weeks after surgery, the model rats were randomized into the following groups: 5/6(A/I) group, 5/6(A/I)+low-dose ICA group, and 5/6(A/I)+high-dose ICA group. Another 12 rats that received sham operation were randomly classified into 2 groups: sham group and sham+ICAH group. Eight weeks after treatment, the expression of collagen-Ⅰ(Col-Ⅰ), collagen-Ⅲ(Col-Ⅲ), mitochondrial dynamics-related proteins(p-Drp1 S616, p-Drp1 S637, Mfn1, Mfn2), and mitochondrial function-related proteins(TFAM, ATP6) in the remnant kidney tissues was detected by Western blot. The expression of α-smooth muscle actin(α-SMA) was examined by immunohistochemical(IHC) staining. The NRK-52 E cells, a rat proximal renal tubular epithelial cell line, were cultured in vitro and treated with ICA of different concentration. Cell viability was detected by CCK-8 assay. In NRK-52 E cells stimulated with 20 ng·mL~(-1) TGF-ß1 for 24 h, the effect of ICA on fibronectin(Fn), connective tissue growth factor(CTGF), p-Drp1 S616, p-Drp1 S637, Mfn1, Mfn2, TFAM, and ATP6 was detected by Western blot, and the ATP content and the mitochondrial morphology were determined. The 20 ng·mL~(-1) TGF-ß1-stimulated NRK-52 E cells were treated with or without 5 µmol·L~(-1) ICA+10 µmol·L~(-1) mitochondrial fusion promoter M1(MFP-M1) for 24 h and the expression of fibrosis markers Fn and CTGF was detected by Western blot. Western blot result showed that the levels of Col-Ⅰ, Col-Ⅲ, and p-Drp1 S616 were increased and the levels of p-Drp1 S637, Mfn1, Mfn2, TFAM, and ATP6 were decreased in 5/6(A/I) group compared with those in the sham group. The levels of Col-Ⅰ, Col-Ⅲ, and p-Drp1 S616 were significantly lower and the levels of p-Drp1 S637, Mfn1, Mfn2, TFAM, and ATP6 were significantly higher in ICA groups than that in 5/6(A/I) group. IHC staining demonstrated that for the expression of α-SMA in the renal interstitium was higher in the 5/6(A/I) group than in the sham group and that the expression in the ICA groups was significantly lower than that in the 5/6(A/I) group. Furthermore, the improvement in the fibrosis, mitochondrial dynamics, and mitochondrial function were particularly prominent in rats receiving the high dose of ICA. The in vitro experiment revealed that ICA dose-dependently inhibited the increase of Fn, CTGF, and p-Drp1 S616, increased p-Drp1 S637, Mfn1, Mfn2, TFAM, and ATP6, elevated ATP content, and improved mitochondrial morphology of NRK-52 E cells stimulated by TGF-ß1. ICA combined with MFP-M1 further down-regulated the expression of Fn and CTGF in NRK-52 E cells stimulated by TGF-ß1 compared with ICA alone. In conclusion, ICA attenuated RIF of CRF by improving mitochondrial dynamics.