Yishen Jiangzhuo Granules(益肾降浊冲剂) Affect Tubulointerstitial Fibrosis via A Mitochondrion-Mediated Apoptotic Pathway

Objective： To investigate the effect of Yishen Jiangzhuo Granules （益肾降浊冲剂 , YSJZG） on mitochondrial injury and regeneration and renal tubular epithelial cell apoptosis in chronic renal failure （CRF） rats and explore its mechanism from molecular pathology, gene, protein levels, and relative pathway. Methods： The CRF rat model was established using 5/6 nephrectomy. Sixty rats were randomly divided into six groups： sham-operation group, model （CRF） group, Niaoduqing Granules （尿毒清颗粒）-treated group [5 g/（kg.day）], low-, moderate-, and high-dose [L-YSJZG, M-YSJZG, H-YSJZG at 3, 6, and 9 g/（kg-day）] YSJZG-treated group （n=10 each）. The levels of serum creatinine （Scr）, blood urea nitrogen （BUN）, and 24-h urine protein were assessed after 10 weeks of treatment. The tubulointerstitial injury and collagen deposition were evaluated using periodic acid-schiff stain and Masson staining. Renal tubular epithelial cell apoptosis was assessed using the terminal deoxynucleotidyl transferase dUTP nick end labeling assay, mitochondrial injury was observed using an electron microscope, and superoxide dismutase （SOD）, glutathione （GSH） and malondialdehyde （MDA） levels were assessed using chromometry. Transforming growth factor- 1 β（TGF-β 1） expression was assessed using immunohistochemistry. The expressions of Bax, Bcl-2, peroxisome proliferator-activated receptor γ coactivator-1 α （PGC-1α）, mitochondrial transcription factor A （Tfam）, mitogen-activated protein kinases （MAPK） phosphorylation were evaluated by Western blot. Results： YSJZG decreased the 24-h urine protein, BUN, Scr, remnant kidney weight-to-body weight ratio, renal tubular injury, deposition of collagen, and the apoptosis of renal tubular epithelial cells in a dose-dependent manner. YSJZG dose-dependently restored the number and structure of mitochondria and the expression of Tfam and PCG-1 α, up-regulated the expression of Bcl-2, and inhibited the expression of Bax. YSJZG also dose-dependently inhibited TGF- 13 1 expression, increased SOD and GSH activity, decreased the MDA level, and inhibited p38MAPK and pERK1/2 phosphorylation （all P〈0.01）. Conclusion： YSJZG improved the renal function in rats with CRF and inhibited the progression of tubulointerstitial fibrosis by dose-dependently alleviating mitochondrial injury, restoring the expression of Tfam and PCG-1α , and inhibiting renal tubular epithelial cell apoptosis through inhibiting activation of reactive oxygen species-MAPK signaling.