miR-155-5P在脓毒症急性肺损伤时调控肺泡巨噬细胞IL-6、MIP-2的表达对中性粒细胞迁移的影响

目的探讨脓毒症急性肺损伤（ALI）时miR-155-5P对肺泡巨噬（MH-S）细胞白介素6、巨噬细胞炎性蛋白2（MIP-2）表达的调控作用及中性粒细胞迁移的影响。 方法培养小鼠MH-S细胞并将其分为对照组、脓毒症组和miR-155-5P抑制物组，miR-155-5P抑制物组预先通过miR-155-5P antagomir完成转染，采用脂多糖干预脓毒症组和miR-155-5P抑制物组12 h，应用RT-PCR检测3组MH-S细胞miR-155-5P、白介素6 mRNA和MIP-2 mRNA的表达，酶联免疫吸附实验检测细胞悬液中白介素6和MIP-2的浓度；再次将MH-S分为上述3组培养在transwell板的下室，CFSE荧光染料标记的中性粒细胞培养在上室，脂多糖干预后应用流式细胞术分别检测上室与下室细胞的荧光值，计算中性粒细胞的迁移率。 结果脓毒症组MH-S细胞的miR-155-5P（8.04±0.65）、白介素6 mRNA（57.05±6.88）和MIP-2 mRNA（52.98±2.58）较对照组（1.00±0.00、1.00±0.00、1.00±0.00）表达明显上调（P<0.05）；白介素6［（50.85±0.12）pg/ml］、MIP-2［（69.96±1.40）pg/ml］的浓度和中性粒细胞迁移率（64.36%）较对照组［（38.58±0.13）pg/ml、（56.00±0.29）pg/ml、30.98%］均显著增加（P<0.05）。而miR-155-5P抑制物组细胞的miR-155-5P表达（0.19±0.35）低于对照组（P<0.05），白介素6 mRNA（39.66±3.65）、MIP-2 mRNA（31.01±2.88）的表达及白介素6［（42.45±1.08）pg/ml］、MIP-2［（59.01±1.63）pg/ml］的浓度也高于对照组（P<0.05），而低于脓毒症组（P<0.05）。 结论脓毒症ALI时，肺泡巨噬细胞miR-155-5P基因高度表达，促炎因子白介素6 mRNA、MIP-2mRNA的表达均明显上调，其促进白介素6、MIP-2的产生，使中性粒细胞大量趋化迁移至肺内，造成肺损伤；而抑制miR-155-5P的表达，可以抑制白介素6、MIP-2的产生，从而减少中性粒细胞的趋化迁移，起到肺保护作用。

miR-155-5P regulates interleukin-6 and macrophage inflammatory protein-2 expression in alveolar macrophages to influence neutrophil migration during acute lung injury in sepsis

ObjectiveTo determine the regulatory effect of miR-155-5P on the expression of interleukin-6 (IL-6) and macrophage inflammatory protein-2 (MIP-2) in alveolar macrophages and the influence on neutrophil migration during acute lung injury (ALI) in sepsis. MethodsMouse alveolar macrophages (MH-S) were cultured and divided into a control group, sepsis group, and miR-155-5P inhibitor group. The miR-155-5P inhibitor group was transfected with miR-155-5P antagomir in advance. Lipopolysaccharide (LPS) was used to intervene the sepsis group and miR-155-5P inhibitor group for 12 h. RT-PCR was used to detect the expression of miR-155-5P, IL-6 mRNA, and MIP-2 mRNA in alveolar macrophages of the three groups, and ELISA was used to detect the concentrations of IL-6 and MIP-2 in cell suspension. Again, MH-S was divided into three groups and cultured in the lower compartment of transwell plate. Neutrophils labeled with CFSE were cultured in the upper compartment. After LPS intervention, fluorescence values of cells in the upper compartment and lower compartment were detected by flow cytometry, respectively, to calculate the migration rate of neutrophils. ResultsThe expression of miR-155-5P (8.04±0.65), IL-6 mRNA (57.05±6.88), and MIP-2 mRNA (52.98±2.58) in MH-S cells in the sepsis group were significantly up-regulated compared with the control group (1.00±0.00, 1.00±0.00, and 1.00±0.00, respectively; P<0.05). The concentrations of IL-6 [(50.85±0.12) pg/ml] and MIP-2 [(69.96±1.40) pg/ml] and neutrophil migration rate (64.36%) were significantly higher sepsis group than in the control group [(38.58±0.13) pg/ml, (56.00±0.29) pg/ml, and 30.98%, respectively; P<0.05]. The expression of miR-155-5P in the miR-155-5P inhibitor group (0.19±0.35) was lower than that in the control group (P<0.05). The expression of IL-6 mRNA (39.66±3.65) and MIP-2 mRNA (31.01±2.88), and the concentrations of IL-6 [(42.45±1.08) pg/ml] and MIP-2 [(59.01±1.63) pg/ml] in the miR-155-5P inhibitor group were significantly higher than those of the control group (P<0.05), but lower than those of the sepsis group (P<0.05). ConclusionIn ALI secondary to sepsis, miR-155-5P is highly expressed in alveolar macrophages, which is positively correlated with the expression of pro-inflammatory factors IL-6 and MIP-2. miR-155-5P promotes the production of IL-6 and MIP-2, and causes a large number of neutrophils to migrate into the lung, thus causing lung injury. Inhibiting the expression of miR-155-5P can inhibit the production of IL-6 and MIP-2, thus reducing the chemotactic migration of neutrophils and protecting the lung.