Abstract： Objective To evaluate the effects of microRNA-155(miR-155)on liver injury in mice with sepsis.Methods One hundred and twenty BALB/c mice were randomly divided into two groups of equal number according to random number table.Sepsis was induced by intraperitoneal injection of lipopolysaccharide(LPS,20 mg/kg).The mice were sacrificed at the time-points of 0,2,6,12,24,48 hours.Blood and liver tissue were collected,and the levels of tumor necrosis factor-α(TNF-α),interleukin(IL-6,IL-10)in serum and liver homogenate and alanine transaminase(ALT)in serum were determined by enzyme linked immunosorbent assay (ELISA).The injury of liver tissue was evaluated by histopathology.The expression of miR-155 in liver tissue was assessed by fluorescent quantitation reverse transcription-polymerase chain reaction(RT-PCR).Results The levels of TNF-α,IL-6 and IL-10 in serum and liver homogenate of septic mice increased with passage of time,and then the levels of TNF-α and IL-6 lowered after reaching the peak value,but remained higher than that of control group.TNF-α(ng/L)reached the peak value at 2 hours post-LPS-injection(serum:1538.46 ± 102.12 vs.64.52 ± 18.44,liver homogenate:255.26 ± 41.23 vs.60.21 ± 13.55,both P＜0.05).The level of IL-6(μg/L)reached the peak value at 6 hours post-LPS-injection(serum:875.33 ± 102.37 vs.153.72 ± 20.67,liver homogenate:9.22 ± 0.82 vs.3.35 ±0.36,both P＜0.05),and that of IL-10(ng/L)reached the peak value at 48 hours post-LPS-injection(serum:520.13 ± 88.52 vs.23.43 ±3.01,liver homogenate:260.12 ±50.38 vs.16.37 ±3.71,both P＜0.05).There were significant differences in above indexes between septic and control group(all P＜0.05).The serum level of ALT(U/L)rose with passage of time,reaching the peak value at 48 hours post-LPS-injection(603.26 ± 70.21 vs.45.84 ± 5.64,P＜0.05).The values showed significant differences between septic and control group(P＜0.05).A large number of leucocytic infiltration was found in liver.Hepatic tissue showed architectural distortion.Hepatocyte vacuolation and nodular necrosis were obvious at 12 hours post-LPS-injection.Relative expression of miR-155 was found to be increased at 2 hours post-LPS-injection,reaching its peak value at 12 hours post-LPS-injection[(72.96 ± 9.34)-fold of control group,P＜0.05].Conclusion The increase in miR-155 expression might play an important role in the mechanism of liver injury during sepsis.