Involvement of miR-155 as ascertained in the mouse gout peritonitis model. Male C57BL/6 J mice (n = 3 per group) used for the experiments were aged 8 to 10 weeks. Peritonitis was induced by intraperitoneal injection of 3 mg monosodium urate crystals in 250 μl PBS. After 24 h, mice were killed and 4 ml PBS containing 25 units/ml heparin was injected into each peritoneal cavity. The peritoneal lavage fluid was aspirated and infiltrated cells were harvested. (A) Inflammatory cytokines were up-regulated. Real-time PCR was performed to determine the mRNA expression of TNF-α and IL-1β. (B) miR-155 is up-regulated in the gout mouse model. (C) Src homology 2-containing inositol phosphatase-1 (SHIP-1) protein level was suppressed on western blot analysis. Values are shown as the mean ± standard error of the mean. *P <0.05, Mann–Whitney U-test.