Rapamycin Inhibites TLR4/Myd88/NF-κB Signaling Pathway And Improves Renal Injury In MRL/lpr Mice

Objective:To investigate the effect of rapamycin(RAPA)on renal injury in MRL/lpr mice and its molecular mechanism.Methods:Forty 20-week-old C57BL/6 and MRL/lpr mice were divided into normal group,treatment group,lupus group and lupus treatment group.Normal group and lupus group,daily intraperitoneal injection of dimethyl sulfoxide(Dimethyl sulfoxide,DMSO).Treatment group,lupus treatment group,daily intraperitoneal injection of RAPA 2.0 mg/kg dissolved by DMSO,the injection lasted for 28 consecutive days.24-hour urinary protein,the blood urea nitrogen(BUN)and serum creatinine(Scr)in peripheral blood were detected.The level of ANA,Anti-ds DNA,Anti-Sm in each group were detected by enzyme linked immunosorbent assay(ELISA).The pathological changes of renal tissue were observed by HE,PAS,Masson and PASM staining.The location of TLR4,Myd88 and p-NF-κB-p65 and Nephrin in renal cortex were detected by immunofluorescence(immunofluorescence,IF).The protein contents of TLR4,Myd88,NF-ΚB-p65,nephrin,podocin,TNF-αand IL-6 were detected by Western Blot,and the relative expression of TLR4,Myd88 and NF-ΚB-p65 were detected by real-time fluorescence quantitative PCR(q PCR).Apoptosis was detected by TUNEL staining.Results:Compared with the normal control group,the levels of 24-hour proteinuria,Blood urea nitrogen,serum creatinine and serum ANA,Anti-ds DNA,Anti-Sm in lupus group were improved than those in normal group(*p<0.05).renal pathological injury were significantly increased(*p<0.05).The protein levels of TLR4,Myd88,NF-ΚB-p65,NF-αand IL-6 and the m RNA levels of TLR4,Myd88,NF-κB-p65 were significantly increased,but the nephrin and podocin were decreased.(~*p<0.05).the apoptotic rate of renal tissue cells also increased(~*P<0.05).Compared with lupus group,the above changes were reversed in lupus treatment group(~#P<0.05).Conclusion:Rapamycin improves renal injury in MRL/lpr mice by inhibiting TLR4/Myd88/NF-κB signaling pathway,and the possible mechanism may be reduced apoptosis in renal tissue in lupus nephritis and improved LN podocyte injury.