Inhibition of Autophagy Attenuated Ethylene Glycol Induced Crystals Deposition and Renal Injury in a Rat Model of Nephrolithiasis

Background/Aims: Nephrolithiasis is a common and frequently occurring disease, its exact pathogenesis is remains unclear. Emerging data suggest that autophagy plays a vital role in the pathophysiological processes of kidney diseases. Therefore, this study was designed to investigate the potential role of autophagy in the formation of calcium oxalate (CaOx) kidney stones in rat model. Methods: Thirty-two rats were randomly divided into four groups (eight rats/group): untreated control group, stone model group, rapamycin-treated group, chloroquine-treated group. Rat models of CaOx nephrolithiasis was administration of 0.75% ethylene glycol (EG) in their drinking water for 4 weeks. Western blot and transmission electron microscope (TEM) were used to detect the expression of autophagy related protein LC3-II, BECN1 and p62 and autophagic vacuoles respectively. Renal function was evaluated by measuring the levels of serum CRE and BUN. Renal tubular injury markers NGAL and Kim-1 was determined by ELISA kits. Von Kossa staining was used to assess crystal deposits and histological tissue injury. TUNEL staining was employed to assess apoptosis of the renal tubular cell. Results: Compare with the controls, the expression of autophagy related protein LC3-II, BECN1 and number of autophagic vacuoles were increased significantly, whereas the p62 protein level was decreased in the stone model group. The levels of apoptosis, serum CRE and BUN, NGAL and Kim-1 in the stone model group were increased compared with the control group and crystals deposition and renal injury were increased significantly. However, the levels of autophagy, kidney injury and crystal deposition were decreased by chloroquine but increased by rapamycin. Conclusion: These findings suggested that rats were administration of ethylene glycol could lead to the formation of CaOx nephrolithiasis and autophagy activation. Inhibiting autophagy could be an effective therapeutic approach for decreasing the formation of nephrolithiasis.