HMGB1 RNA干扰对博莱霉素诱导肺纤维化小鼠α平滑肌肌动蛋白的抑制作用

HMGB1 RNAi inhibits α-smooth muscle actin expression in mice with bleomycin-induced lung fibrosis

目的观察RNA干扰降低高迁移率族蛋白B1(HMGB1)在肺内的表达对博莱霉素致肺纤维化小鼠α平滑肌肌动蛋白(α-SMA)表达的影响,探讨HMGB1在肺纤维化上皮间质转分化中的作用。方法将40只4～6周龄C57BLB/c雄性小鼠随机分为PBS对照组(气管滴入PBS),纤维化组(气管滴入博莱霉素3 mg/kg),HMGB1 RNAi组(气管滴入博莱霉素3 mg/kg+气管滴入siRNA 20μl)和RNAi阴性对照组(气管滴入博莱霉素3 mg/kg+气管滴入siRNA阴性对照20μl)。实验第10天处死小鼠,肺组织切片行HE和Masson染色观察肺组织病理改变,RT-PCR法检测HMGB1和α-SMA的表达。免疫组化检测HMGB1和α-SMA蛋白表达。结果 RNAi组肺病理损伤较纤维化组减轻,气道上皮下胶原沉积减少,肺组织HMGB1 mRNA表达和蛋白表达均显著下降(P<0.01);同时,RNAi组肺α-SMA的mRNA表达和蛋白表达亦较纤维化组明显减少(P<0.01)。结论 HMGB1 RNAi抑制了HMGB1表达,减轻了博莱霉素诱导的肺纤维化改变,可能与其抑制α-SMA的活化和表达有关。

The high mobility group B1 （HMGB1） is a nuclear protein that is present in almost all eukaryotic cells and is highly conserved between species. In this study, we aimed to investigate the effect of down-regulating HMGB1 expression by RNAi on the expression of a-smooth muscle actin （a-SMA） in mice with lung fibrosis induced by bleomycin. Forty C57BL/c male mice aged from 4 to 6 weeks were randomly divided into control group, bleomyein group, bleomycin plus HMGB1 RNAi group, and RNAi negative control group. Bleomycin group were treated with bleomycin （3 mg/kg） via endotracheally injection on day 0, while control group were treated with PBS. And bleomycin plus HMGB 1 RNAi group were received HMGB 1 siRNA plus bleomycin intratracheal administration. RNAi negative control group were received negative siRNA plus bleomyein intratracheal administration. Mice were sacrificed at day 10 after the treatments. The lung tissue was examined with HE staining and Masson staining for pathological changes, and also detected by immunohistochemistry for HMGB 1 and a-SMA expresion. The mRNA expression of HMGB 1 and a-SMA was detected by reverse transeriptase-polymerase chain reaction （RT-PCR）. Histological examination of lung specimens demonstrated that HMGB1 siRNA administration lessened bleomycin-induced lung fibrosis and significantly reduced collagen accumulation. HMGB 1 mRNA and protein expression in HMGB 1 siRNA-treated mice was significantly decreased （P〈 0.01）. The expression levels of a-SMA mRNA and protein were also inhibited by HMGB1 RNAi treatment in mice with intratracheal administration of bleomycin （P 〈 0.01）. In conclusion, HMGB1 RNAi alleviate the bleomycin-induced lung fibrosis by downregulating the expression of a-SMA.