Lipopolysaccharide-induced podocyte injury is mediated by suppression of autophagy.

Abstract

High-level autophagy has an important role in maintaining the stable state of podocytes. The present study explored the influence of lipopolysaccharide (LPS) on autophagic activity in podocytes and demonstrated its mechanistic involvement in LPS-induced injury. Conditionally immortalized podocytes were cultured invitro and were treated with chloroquine (CQ), LPS, LPS+rapamycin or LPS+3‑methyladenine (3‑MA). The autophagic vesicles and endoplasmic reticulum were observed using transmission electron microscopy. The tandem mRFP‑GFP‑LC3 adenovirus was used to detect autophagosomes and autolysosomes. The expression levels of light chain3‑II (LC3II), beclin‑1, P62, CCAAT‑enhancer‑binding protein homologous protein (CHOP) and podocin were determined by western blot analysis. Autophagic vesicles were detected in podocytes under basic conditions. CQ was found to increase the protein levels of LC3II in a time‑dependent manner (2, 4 or 6h), confirming the high activity of autophagy in podocytes. Compared with the control group, LPS induced the expansion of the endoplasmic reticulum and high expression levels of CHOP, while decreasing the protein expression of podocin. Notably, podocytes treated with LPS showed decreases in LC3II and beclin‑1 levels and autophagosome/autolysosome numbers, which was accompanied by high P62 levels. Furthermore, the autophagy enhancer rapamycin reversed the downregulation of LC3II and podocin, and the upregulation of CHOP induced by LPS, while the autophagy inhibitor 3‑MA aggravated the effects of LPS. In conclusion, the present study demonstrated that LPS inhibited podocyte autophagy, which contributed to LPS-induced injury of podocytes.