Klotho, an aging-suppression protein, inhib its TLR4/NF-kB p65/NGAL pathways in rat mesangial cells cultured with high glucose and its mechanism / 中华内分泌代谢杂志

ABSTRACT

Objective To explore the changes in expression of Klotho, an aging-suppression protein, and neutrophil gelatinase associated lipocalin ( NGAL) and their relationship with rat mesangial cells ( RMCs) cultured with high glucose in vitro, and to explore the role played by Toll-like receptor-4 (TLR4) / nuclear factor-kB(NF-kB) p65 pathways in this process. Methods Three NGAL-siRNA sequences were designed and synthesized. The effective sequence in subsequent experiments was chosen. RMCs were preincubated with pyrrolidinedithiocarbamate (PDTC)or exogenously added Klotho prior to high glucose treatment. Realtime PCR was used to analyze Klotho, TLR4, NGAL mRNA expressions. Western blot was used to observe Klotho, TLR4,NF-kB p65, NGAL,fibronectin (FN), and connective tissue growth factor ( CTGF) protein expression. ELISA assay was used to detect monocyte chemoattractant protein-1 ( MCP-1) and CXCL5 secretions. Results High glucose suppressed Klotho expression significantly(P<0. 05) and activated TLR4 / NF-kB p65 pathway. Meanwhile,the levels of NGAL,FN,CTGF, MCP-1, and CXCL5 were highly expressed ( P < 0. 01). NGAL gene silencing obviously down-regulated the increased expressions of FN, CTGF, MCP-1, and CXCL5 ( P < 0. 01). After PDTC treatment the overexpression of NGAL protein was markedly lowered(P<0. 01). In addition, Klotho treatment significantly inhibited the activity of TLR4 /NF-kB p65 pathways and down-regulated the expressions of NGAL, FN, CTGF, MCP-1 and CXCL5 stimulated by high glucose(P<0. 01). Conclusion Klotho inhibits the activity of TLR4 / NF-kB p65 pathways and thus inhibits NGAL expression in RMCs cultured with high glucose in vitro. And then it suppresses the expressions of FN, CTGF, MCP-1, and CXCL5. This provides a new basis to illustrate the protection mechanism of the anti-aging protein Klotho in diabetic nephropathy, and may provide new ideas and therapeutic targets for prevention and treatment.