胰岛素通过激活SGK1对LPS诱导的急性肺损伤状态下钠离子通道的调节作用

Insulin Promotes Epithelial Sodium Channel in LPS induced Acute Lung Injury via SGK1 Signaling Pathway

目的探讨胰岛素通过SGK1对LPS诱导的急性肺损伤状态下的钠离子通道的调节作用。方法 30只雄性Wistar大鼠随机平均分为对照组(Control组)、治疗组(LPS+Insulin组)和模型组(LPS组)每组10只。记录5个时间点(0、0.5、1、3、6h)大鼠的血糖水平,并使用胰岛素使LPS+Insulin组大鼠血糖控制在1.5到4.5mmol/L。通过HE染色观察肺组织病理学改变;使用湿/干比(W/D)分析肺水肿程度;使用RT-PCR、Western blot和免疫组织化学对α-ENaC的表达进行测量;SGK1和磷酸-SGK1(phospho-SGK1)蛋白表达使用Western blot进行定量分析。结果大鼠注射LPS后血糖明显上升并于3h达到最大值。LPS干预6h后大鼠肺损伤评分和W/D比值明显增加,α-ENaC表达量和磷酸化-SGK1水平明显下降,差异有显著统计学意义。同时发现,LPS+Insulin组大鼠肺损伤评分和W/D比值较LPS组大鼠稍低,而α-ENaC表达量和磷酸化-SGK1水平较之升高,差异均有统计学意义(P<0.05)。结论胰岛素可以有效减轻LPS诱导的大鼠ARDS导致的肺水肿,其机制可能与促进SGK1的活化后上调了ENaC的表达相关。该结果为应用胰岛素治疗肺水肿奠定了理论基础。

Objective To investigate the role of insulin on the regulation of ENaC via SGK1 in LPS-induced acute lung injury in rats. Methods Thirty male Wistar rats were randomly divided into three groups--Control group, LPS-I-In- sulin group and LPS group （n=10）. Blood glucose level of rats in five point-in-time（0,0.5h, 1h, 3h and 6 h）, was recorded with blood glucose level of LPS＋Insulin group rats on 1.5 to 4. 5mmol/L. HE staining was used to evaluate the pathological changes in lung. Wet to dry ratio （W/D） was included to measure the degree of lung edema. RT-PCR, Western blot and immunohistochemistry were used to measure expression of α-ENaC. Then, SGK1 and phosphorylated SGK1 were evaluated by Western blot as well. Results After 6h LPS injection, severe pathological changes, increased W/D, down-regulated α-ENaC expression and reduced phosphorylated SGK1/total SGK1 were found. However, compared with LPS group, pathological changes and W/D were significantly ameliorated, meanwhile, α-ENaC expression and phosphorylated SGK1/total SGK1 were notably increased in LPS＋Insulin group. Conclusion Our findings demonstrated that insulin up-regulates ENaC in vivo possibly resulting from activation of SGK1.