Qi Di, He Jing, Wang Daoxin, Deng Wang, Zhao Yan, Ye Yuan, Feng Longhua
Respir Res. 2014 Dec 31;15(1):159. doi: 10.1186/s12931-014-0159-1.
17β-estradiol can suppress acute lung injury (ALI) and regulate alveolar epithelial sodium channel (ENaC). However the relationship between these two functions remains unclear. This study is conducted to assess the role of ENaC and the PI3K/Akt/SGK1 signaling pathway in 17β-estradiol therapy in attenuating LPS-induced ALI.
ALI was induced in C57BL/J male mice by intratracheal administration of lipopolysaccharide (LPS). Concurrent with LPS administration, 17β-estradiol or sterile saline was administered to ALI model with or without the phosphoinositide 3-kinase (PI3K) inhibitor wortmannin. The lung histological changes, inflammatory mediators in bronchoalveolar lavage fluid (BALF), wet/dry weight ratio (W/D) and alveolar fluid clearance (AFC) were measured 4 hours after LPS challenge in vivo. For in vitro studies, LPS-challenged MLE-12 cells were pre-incubated with or without wortmannin for 30 minutes prior to 17β-estradiol treatment. Expression of ENaC subunits was assessed by reverse transcriptase PCR, western blot, cell surface biotinylation, and immunohistochemistry. The levels of phosphorylated Akt and SGK1 in lung tissue and lung cell lines were investigated by western blot.
17β-estradiol suppressed LPS-mediated ALI in mice by diminishing inflammatory mediators and enhancing AFC. 17β-estradiol promoted the expression and surface abundance of α-ENaC, and increased the levels of phosphorylated-Akt and phosphorylated-SGK1 following LPS challenge. This induction was abolished by the PI3K inhibitor wortmannin in vivo and in vitro.
17β-estradiol attenuates LPS-induced ALI not only by repressing inflammation, but also by reducing pulmonary edema via elevation of α-ENaC expression and membrane abundance. These effects were mediated, at least partially, via activation of the PI3K/Akt/SGK1 signaling pathway.
17β-雌二醇可抑制急性肺损伤（ALI）并调节肺泡上皮钠通道（ENaC）。然而，这两种功能之间的关系仍不清楚。本研究旨在评估ENaC及PI3K/Akt/SGK1信号通路在17β-雌二醇减轻脂多糖（LPS）诱导的ALI治疗中的作用。
通过气管内给予脂多糖（LPS）诱导C57BL/J雄性小鼠发生ALI。在给予LPS的同时，对ALI模型给予17β-雌二醇或无菌生理盐水，其中部分模型同时给予或不给予磷酸肌醇3-激酶（PI3K）抑制剂渥曼青霉素。在体内LPS攻击4小时后，测量肺组织学变化、支气管肺泡灌洗液（BALF）中的炎症介质、湿/干重比（W/D）和肺泡液体清除率（AFC）。对于体外研究，在17β-雌二醇处理前30分钟，将LPS刺激的MLE-12细胞与或不与渥曼青霉素预孵育。通过逆转录聚合酶链反应（RT-PCR）、蛋白质印迹法、细胞表面生物素化和免疫组织化学评估ENaC亚基的表达。通过蛋白质印迹法研究肺组织和肺细胞系中磷酸化Akt和SGK1的水平。
17β-雌二醇通过减少炎症介质和增强AFC抑制LPS介导的小鼠ALI。17β-雌二醇促进α-ENaC的表达和表面丰度，并在LPS攻击后增加磷酸化-Akt和磷酸化-SGK1的水平。PI3K抑制剂渥曼青霉素在体内和体外均消除了这种诱导作用。
17β-雌二醇减轻LPS诱导的ALI不仅通过抑制炎症，还通过提高α-ENaC表达和膜丰度来减轻肺水肿。这些作用至少部分是通过激活PI3K/Akt/SGK1信号通路介导的。
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