Rapamycin inhibits HMGB1 expression and releases in RAW264.7 cells induced by lipopolysaccharides in vitro

AIM:To observe the mechanism that rapamycin(RPM)affects HMGB1 expression and release in RAW264.7 cells induced by lipopolysaccharides(LPS).METHODS:RAW264.7 cells were cultured in six wells plate and divided into five groups:control group,250 μg/L LPS treatment group,100 μg/L RPM treatment group,50 μg/L rTNF-α treatment group and 100 μg/L TNF-α antibody treatment group.After 4 h treatment,the TNF-α level in the culture media was evaluated by ELISA assay.After 24 h,the expression of HMGB1 mRNA was measured by RT-PCR,and HMGB1 protein level in the culture media was determined by Western blotting analysis.RESULTS:TNF-α level in the culture media of RAW264.7 cells has no significant difference between RPM treatment group and control group(P0.05).Both HMGB1 mRNA expression and HMGB1 protein level were remarkably higher in LPS treatment group than that in control group(P0.05).RPM attenuated LPS-induced HMGB1 mRNA and HMGB1 accumulation.Compared with that in RPM treatment group,HMGB1 accumulation was increased in rTNF-α treatment group,and had no significant difference in TNF-α antibody treatment group(P0.05).CONCLUSION:RPM inhibits HMGB1 expression not only by directly suppressing STAT3 activation,but also by indirectly reducing TNF-α level.