巨噬细胞向肌成纤维细胞转化促进LPS诱导的急性肺损伤模型小鼠肺纤维化

Macrophage-to-myofibroblast transition promotes pulmonary fibrosis occurred in LPS-induced acute lung injury of mouse models

目的探讨巨噬细胞向肌成纤维细胞转化(MMT)在脂多糖(LPS)诱导的急性肺损伤小鼠肺纤维化过程中的作用。方法将21只小鼠分为7组:对照组、不同时间点LPS诱导小鼠早期肺纤维化(LPS-PF)模型组和不同时间点氯磷酸二钠脂质体(CL-LIP)干预组(n=3)。用HE、Masson染色评估各组肺纤维化程度;用免疫荧光检测MMT过程中CD68和α-平滑肌动蛋白(α-SMA)共标记阳性细胞数量。骨髓来源巨噬细胞(BMDMs)分为对照(Ctrl)组和转化生长因子-β1(TGF-β1)刺激组(n=3);用RT-qPCR检测各组α-SMA、纤连蛋白(FN)、人I型胶原蛋白(Col1)表达水平。用Western blot检测各组间α-SMA以及Smad同源物3(Smad3)、磷酸化的Smad3(p-Smad3)蛋白表达量。结果LPS-PF模型小鼠肺组织第7天Ashcroft评分较对照(Ctrl)组显著增高(P<0.01);但在CL-LIP组中肺纤维化程度较LPS-PF组明显减轻(P<0.05)。肺组织免疫荧光染色发现,CL-LIP组CD68α-SMA共标记阳性细胞数较LPS-PF组对应时间点明显减少(P<0.01)。体外实验中,TGF-β1刺激组48 h、96 h后α-SMA、FN、Col1较对应时间点表达量明显增加(P<0.01)。检测体内、体外实验中Smad3、p-Smad3的蛋白表达量,发现LPS-PF组(第7天、第10天)和TGF-β1刺激组(48 h和96 h)均较各自对照(Ctrl)组明显增加(P<0.01)。结论MMT具有促进LPS诱导模型小鼠肺纤维化的作用,其转化过程可能经Smad3调节。

Objective To explore the impact of macrophage-to-myofibroblast transition(MMT)on pulmonary fibrosis induced by acute lung injury by LPS.Methods Totally 21 male mice were randomly classified into 7 groups:control group,model group(LPS-PF)at different time points and intervention group of clodronate-liposomes(CL-LIP)treatement at different time points(n=3).Pulmonary fibrosis was identified by HE and Masson staining microscopy.The immuno-fluorescence technology was used for the evaluation of numbers of macrophage-to-myofibroblast transition cells(MMT cell which co-expressed CD68 andα-SMA).Bone marrow-derived macrophages(BMDMs)were randomly classified into two group:control(Ctrl)group and TGF-β1-treated group induced by transforming growthfactor-β1.α-SMA,FN and Col1 were detected by RT-qPCR.The expression ofα-SMA,Smad3 and p-Smad3 protein was evaluated by Western blot.Results At day 7,the Ashcroft score of lung tissue in LPS-PF mouse model was significantly increased when compared with the Ctrl group(P<0.01);While the score significantly declined when the model was pretreated with CL-LIP(P<0.05).As detected by immuno-fluorescence staining,in CL-LIP group the number of CD68-positive cells co-labeled withα-SMA was obviously less then that of LPS-PF group of the corresponding time point(P<0.01).When the BMDMs were stimulated by TGF-β1 at 24 h,48 h and 96 h respectively,a higher expression ofα-SMA,FN,Col1,were found in TGF-β1-treated group than that in Ctrl group at the corresponding time point(P<0.01).The expression of Smad3,p-Smad3 significantly higher in LPS-PF group(at both day 7 and day 10)and TGF-β1-treated group(at both 48 h and 96 h)as compared to corresponding control group(P<0.01).Conclusions MMT promotes pulmonary fibrosis induced by ALI via LPS.Smad3 is proved to be involved in the MMT process.