地塞米松通过抑制GITR/GITRL信号减轻脂多糖诱导的血管内皮细胞凋亡

Dexamethasone protects vascular endothelial cells from LPS-induced apoptosis via inhibiting GITR/GITRL signaling pathway

目的本研究通过观察地塞米松对急性呼吸窘迫综合征(ARDS)小鼠模型肺部炎症反应及GITR/GITRL信号通路的影响,同时初步探讨地塞米松对LPS诱导人血管内皮细胞GITRL表达以及细胞凋亡的作用。方法制作ARDS动物模型后,取小鼠肺组织行常规HE染色,同时行免疫组化染色检测GITR/GITRL信号蛋白,另外行肺泡灌洗并收集灌洗液(bronchoalveolar lavage fluid,BALF)分类计数炎症细胞,ELISA检测BALF中的炎症因子。利用免疫荧光检测人血管内皮细胞GITRL的表达,另外用流式细胞学分析检测凋亡细胞比例。结果地塞米松明显减少模型小鼠BALF中的炎症细胞以及炎症因子,利用免疫组织化学方法检测实验小鼠肺组织中的GITR/GTIRL信号蛋白发现:对照组小鼠肺组织中有少许的炎性细胞表达GITR;ARDS模型模型组小鼠肺组织中可见明显GITR蛋白表达,主要表达于浸润的炎性细胞;地塞米松干预ARDS模型小鼠后肺组织中GITR表达明显减少;对照组小鼠肺组织中GITRL主要表达于血管内皮细胞,其他组织细胞有少量表达;ARDS模型组小鼠肺组织中可见明显GITRL蛋白表达;地塞米松干预ARDS模型小鼠后肺组织中GITRL表达明显减少。利用流式细胞学分析凋亡比例结果显示:IFN-α组血管内皮细胞凋亡细胞比例明显高于正常对照组,地塞米松干预IFN-α诱导的血管内皮细胞凋亡比例较单独IFN-α干预组明显减少。结论地塞米松减轻ARDS肺部炎症可能通过抑制GITR/GITRL信号减轻IFN-α诱导的血管内皮细胞凋亡来实现。

This study was designed to investigate the effects of dexamethasone on pulmonary inflammation and GITR/GITRL signaling pathway in acute respiratory distressyndrome(ARDS) mouse models, and investigate the effects of dexamethasone on LPS-induced GITRL expression and apoptosis in human vascular endothelial cells.Dexamethasone significantly reduced inflammatory cells and inflammatory factors in BALF of model mice. Moreover,the expression of GITR and GITRL proteins were significantly increased in the lung tissue of the ARDS model group,and the expression of proteins was significantly decreased after intervention by dexamethasone. Flow cytometry analysis showed that dexamethasone significantly reduced the proportion of vascular endothelial cell apoptosis induced by IFN-α;while ZVAD-fmk also reduced the proportion of vascular endothelial cell apoptosis induced by IFN-α. The results show that dexamethasone may reduce lung inflammation in ARDS by inhibiting GITR/GITRL signaling and inhibiting IFN-α-induced apoptosis of vascular endothelial cells.