不同时期骨髓间充质干细胞移植对矽肺大鼠CD4^+CD25^+调节性T细胞的影响

Effects of bone mesenchymal cells transplantation in different periods on expression of CD4^+CD25^+ regulatory T cells in rats with silicosis

目的探讨在不同时间窗进行骨髓间充质干细胞(bone mesenchymal stem cells,BMSCs)移植对矽肺大鼠外周血CD4^+CD25^+调节性T细胞(regulatory T cells,Tregs)水平的影响。方法将42只SD雌性大鼠随机分为4组:对照组、矽肺模型组、早期治疗组(n=12)和晚期治疗组(n=6)。采用暴露式气管内一次性缓慢注入SiO_2混悬液建立矽肺大鼠模型,早期治疗组和晚期治疗组并分别于造模后第6 h和第42天经尾静脉注射BMSCs。造模后第14天对照组、矽肺模型组,早期治疗组分别处死大鼠各6只,造模后第56天各组分别处死6只。HE染色观察肺组织形态学变化,流式细胞仪检测外周血Tregs/CD4+比率。结果矽肺模型组在造模后第14天,肺组织病理改变以急性炎症反应为主,在造模后第56天以纤维化为主;早期治疗组和和晚期治疗组病理改变均较同时期矽肺模型组轻。外周血Tregs/CD4+比率,矽肺模型组大鼠明显下降(P<0.01),早期治疗组和晚期治疗组在BMSCs治疗后第14天均有明显升高(P<0.01),但早期治疗组到治疗后第56天升高效果已不明显(P>0.05)。结论 BMSCs移植可能通过上调Tregs水平,延缓矽肺的纤维化进程。

[Objective]To investigate the effects of bone mesenchymal stem cells（BMSCs）transplantation at different time points on expression of CD4^＋CD25^＋regulatory T cells（Tregs）in rats with silicosis.[Methods]Forty-two healthy female SD rats were randomly divided into 4 groups：control group,silicosis model group,early treatment group（n =12）,and late treatment group（n=6）.The silicosis model was made by one-time infusion of SiO_2 suspension liquid using the exposed tracheal intubation,and the vein injection of BMSCs was given at the first 6 hours and 42 days of silicosis modeling to establish early treatment group and late treatment group respectively.6 rats in each of control group,silicosis model group and early treatment group were sacrificed on the14 th day,and 6 rats in each group were sacrificed on the 56 th day after the model was established.The morphological changes of the lung tissues were observed by HE staining,and the percents of Tregs in CD4~＋（Tregs/CD4~＋）were detected by flow cytometry.[Results]Silicosis model group was dominated by acute inflammatory response on the 14 th day,and fibrosis reaction on the 56 th day after the model was established.Compared with silicosis model group,the pathological changes in early treatment group and late treatment group were improved.Tregs/CD4＋in peripheral blood in silicosis model group were lower than that in control group（P〈0.01）.Tregs/CD4^＋ in early treatment group and late treatment group were significantly elevated on the 14 th day,while elevated value in early treatment group was not significant on the 56 th day after BMSCs treatment（P〉0.05）.[Conclusion] BMSCs transplantation may attenuate the progress of silica-induced lung fibrosis through increasing generation of Tregs.