支气管肺发育不良小鼠肺组织FOXP3^(+)调节性T细胞(Treg)数量减少且向RORγt^(+)FOXP3^(+)Treg转换

The number of FOXP3^(+)regulatory T cells(Tregs)decreased and transformed into RORγt^(+)FOXP3^(+)Tregs in lung tissues of mice with bronchopulmonary dysplasia

目的 探讨调节性T淋巴细胞(Treg)表型转换在支气管肺发育不良(BPD)小鼠肺组织中的作用。方法 C57BL/6新生小鼠随机分成空气组及高氧组,每组10只,高氧组建立新生小鼠高氧暴露的BPD动物模型。在小鼠生后7 d和14 d,每组各处死5只小鼠,取出新鲜肺组织。HE染色观察肺组织病理变化,Western blot法检测肺表面活性蛋白C(SP-C)表达水平;流式细胞术检测肺组织中叉头盒P3(FOXP3)^(+)Treg及维甲酸相关孤核受体γt(RORγt)^(+)FOXP3^(+)Treg占CD4^(+)淋巴细胞百分比,ELISA检测肺组织中白细胞介素17A(IL-17A)、 IL-6的含量。采用Spearman相关分析法分析FOXP3^(+)Treg与SP-C相对表达量的相关性以及RORγt^(+)FOXP3^(+)Treg与IL-17A、 IL-6含量的相关性。结果 与同时间点空气组相比,高氧组肺泡结构简单化,放射状肺泡计数与SP-C相对表达水平均明显下降,高氧组FOXP3^(+)Treg占比减少,RORγt^(+)FOXP3^(+)Treg占比增多,肺组织IL-17A、 IL-6含量明显升高。FOXP3^(+)Treg与SP-C相对表达水平呈正相关,RORγt^(+)FOXP3^(+)Treg与IL-17A、 IL-6含量呈正相关。结论 BPD小鼠肺组织FOXP3^(+)Treg数量减少并向RORγt^(+)FOXP3^(+)Treg转换,可能参与高氧所致肺损伤。

Objective To explore the phenotypic conversion of regulatory T cells(Tregs)in the lungs of mice with bronchopulmonary dysplasia(BPD)-affected mice.Methods A total of 20 newborn C57BL/6 mice were divided into air group and hyperoxia group,with 10 mice in each group.The BPD model was established by exposing the newborn mice to hyperoxia.Lung tissues from five mice in each group were collected on postnatal days 7 and 14,respectively.Histopathological changes of the lung tissues was detected by HE staining.The expression level of surfactant protein C(SP-C)in the lung tissues was examined by Western blot analysis.Flow cytometry was performed to assess the proportion of FOXP3^(+)Tregs and RORγt^(+)FOXP3^(+)Tregs in CD4^(+)lymphocytes.The concentrations of interleukin-17A(IL-17A)and IL-6 in lung homogenate were measured by using ELISA.Spearman correlation analysis was used to analyze the correlation between FOXP3^(+)Treg and the expression of SP-C and the correlation between RORγt^(+)FOXP3^(+)Tregs and the content of IL-17A and IL-6.Results The hyperoxia group exhibited significantly decreased levels of SP-C and radical alveolar counts in comparison to the control group.The proportion of FOXP3^(+)Tregs was reduced and that of RORγt^(+)FOXP3^(+)Tregs was increased.IL-17A and IL-6 concentrations were significantly increased.SP-C was positively correlated with the expression level of RORγt^(+)FOXP3^(+)Tregs.RORγt^(+)FOXP3^(+)Tregs and IL-17A and IL-6 concentrations were also positively correlated.Conclusion The number of FOXP3^(+)Tregs in lung tissue of BPD mice is decreased and converted to RORγt^(+)FOXP3^(+)Tregs,which may be involved in hyperoxy-induced lung injury.