To investigate the effect of microRNA-155 (miR155) agonist on inflammatory response during liver injury in septic mice.

A total of 80 male mice were randomly divided into the sham operation group, sepsis group, microRNA (miRNA) group and miR-155 group, 20 in each group. The model of sepsis was produced by cecal ligation and puncture (CLP), and mice in the sham operation group received the same procedure except for ligation and puncture. Mice in the miRNA group and miR-155 group were given miRNA and miR-155 agonist respectively via the tail vein at 48 h after CLP, and mice in the sham operation group and sepsis group were injected with equal isotonic NaCl solution. Ten mice in each group were used to observe their survival condition on 7 d, and the others in each group were used to collect peripheral blood on 5 d after CLP. The levels of miR-155 and alanine aminotransferase (ALT) were determined and compared. The levels of interleukin-10 (IL-10) and tumor necrosis factor-alpha (TNF-α) were detected by enzyme-linked immunosorbent assay (ELISA).

On 7 d after CLP, 10 mice in the miR-155 group all died, 10 mice in the sham operation group all survived, and 2 mice survived in the sepsis group and miRNA group respectively. The levels of serum miR-155, ALT, IL-10 and TNF-α among four groups on 5 d after CLP were significantly different (F = 46.536, P < 0.001; F = 39.194, P = 0.002; F = 39.228, P = 0.002; F = 83.400, P < 0.001). Moreover, the levels of miR-155, ALT, IL-10 and TNF-α in the sepsis group, miRNA group and miR-155 group were significantly higher than those in the sham operation group (all P < 0.05). Compared with the sepsis group and miRNA group, the levels of miR-155, ALT and IL-10 increased obviously, and the level of TNF-α decreased remarkably in the miR-155 group (all P < 0.05).

The miR-155 agonist can improve the IL-10 level and reduce the TNF-α level, thereby aggravating liver injury in septic mice.