The trend of changes in expression of Klotho and autophagy in sepsis-induced acute kidney injury mice model

Abstract

Objective To investigate the relationship between Klotho and autophagy in sepsis-induced acute kidney injury mice model. Methods The male healthy Balb/c mice were used to establish the model of sepsis-induced acute kidney injury by using cecal ligation and puncture(CLP). Mice were sacrificed at 3 h, 6 h, 12 h, 1 d, 2 d, 3 d, and 5 d after CLP (n=12 for each interval) and on 1 d 6 mice in sham group as well as 6 mice in normal group were sacrificed at the same time. Scr and BUN in the blood serum were detected. The HE and PAS staining were employed for observation on the histopathological changes in kidney tissues under light microscope. The autophagosomes were observed under transmission electron microscope (TEM). The renal protein of Klotho, LC3 and P62 were detected by using Western blot and Immunohistochemistry. Statistical analyses were performed using Student’s t-test by SPSS 23.0. software. Results Scr and BUN increased significantly after CLP, especially on 1 d, respectively (165.64±20.56) μmol/L and (45.51±4.05) mmol/L. HE and PAS staining showed renal tissue was damaged obviously 1 d after CLP, as indicated by desquamation of the brush border of proximal tubular epithelial cells, appearance of bare basement membrane, and interstitial inflammatory cell infiltration. Under TEM, autophagosomes and phagocytosis were observed. Compared with sham group, the expression of Klotho protein decreased gradually from 3 h to 1 d and dropped to the trough at 1 d (t=51.851, P<0.01), then resumed gradually from 2 d to 5 d. On the contrary, the activation of autophagy increased as indicated by the expression of LC3-II/L3-I and p62. Autophagy was induced gradually from 3 h to 1 d and reached peak at 1 d, then declined gradually from 2 d to 5 d (P<0.01). The protein of Klotho and LC3-Ⅱ mainly distributed in renal tubular cytoplasm, and Klotho was reduced significantly (t=-8.371, P<0.01)and LC3-Ⅱappeared in high density remarkably (t=4.995, P=0.001)on 1 d after CLP. Conclusions Klotho protein reduction and autophagy protein increase were observed in sepsis-induced acute kidney injury, and the expressions of Klotho and autophagy acted out in certain extent of time dependence. Key words: Sepsis; Acute kidney injury; Klotho; Autophagy; CLP; LC3-Ⅱ; P62; Mice