Adipolin/CTRP12对LPS致ARDS小鼠的保护作用及肺泡上皮钠离子通道的调节

目的:探讨adipolin/CTRP12对LPS致ARDS小鼠的作用及肺泡上皮钠离子通道(ENaC)的调节。方法:40只C57BL/6J小鼠按随机数字表分为对照组、LPS组、adipolin组和wortmannin(PI3K抑制剂)组,每组10只。苏木精-伊红(HE)染色观察肺组织病理改变;伊文氏蓝标记蛋白检测肺水清除率(AFC),BCA法测支气管肺泡灌洗液(BALF)中蛋白含量,评估肺组织通透性改变;ELISA检测BALF中白细胞介素(IL)-1β和肿瘤坏死因子(TNF)-α含量,髓过氧化物酶(MPO)试剂盒检测MPO活性,吉姆萨染色计数BALF总细胞数和多形核白细胞数,Western blot法检测肺组织α-ENaC蛋白表达和Akt磷酸化水平,实时荧光定量PCR检测肺组织α-ENaC的mRNA转录水平。结果:与control组相比,LPS组表现出典型的ARDS病理改变,肺损伤明显(P0.05),湿干重比(W/D)和BALF蛋白含量明显增高而AFC明显减弱(P0.05),BALF细胞计数、MPO活性、IL-1β含量和TNF-α含量明显升高(P0.05),而肺α-ENaC表达和Akt磷酸化水平显著下调(P0.05)。与LPS组相比,adipolin组肺损伤明显减轻(P0.05),W/D和BALF蛋白含量明显降低而AFC明显增强(P0.05),且BALF细胞计数、MPO活性、IL-1β含量和TNF-α含量均较LPS组显著降低(P0.05),伴α-ENaC表达和Akt磷酸化水平显著上调(P0.05)。而PI3K抑制剂wortmannin组与adipolin组相比,其肺损伤明显加重(P0.05),W/D和BALF蛋白含量明显增高,AFC明显减弱(P0.05),BALF细胞计数、MPO活性、IL-1β含量和TNF-α含量明显升高(P0.05),同时伴α-ENaC表达和Akt磷酸化水平显著下调(P0.05)。结论:Adipolin/CTRP12可通过PI3K/Akt信号通路介导的α-ENaC上调机制,增强肺水肿液清除能力,从而对LPS所致ARDS小鼠发挥保护性调控作用。

Adipolin/CTRP12 protects against LPS-induced ARDS by up-regulating alveolar epithelial sodium channel in mice

AIM: To investigate the effect of adipolin/CTRP12 in LPS-induced acute respiratory distress syndrome(ARDS) and its potential regulation on alveolar epithelial sodium channel(ENaC) in mice. METHODS: C57BL/6J mice(n=40) were randomly divided into control group, LPS group, adipolin group and wortmannin(PI3K inhibitor) group with 10 mice in each group using random number table. The pathological changes of the lung tissues were evaluated by HE staining. The alveolar fluid clearance(AFC) was measured by Evans blue-marked albumin, and the concentrations of total protein in bronchoalveolar lavage fluid(BALF) were assessed by bicinchoninic acid(BCA) method. In BALF, the levels of IL-1β and TNF-α were determined by ELISA, and the activity of myeloperoxidase(MPO) was detected by an MPO assay kit. The total cell counts and polymorphonuclear neutrophil(PMN) counts in the BALF were analyzed by Giemsa staining. The mRNA levels of α-ENaC were assessed by qPCR, while the protein levels of α-ENaC and p-Akt were determined by Western blot. RESULTS: Compared with control group, the classic ARDS pathological changes were observed in the mice in LPS group, manifesting by severe pathological lung injury(P<0.05), increases in W/D weight ratio, total protein levels, cell counts, MPO activitiy, and IL-1β and TNF-α levels in the BALF, and decrease in AFC(P<0.05), accompanied by down-regulated levels of α-ENaC and p-Akt in the lung tissues(P<0.05). The deteriorating effects triggered by LPS were significantly reversed by administration of adipolin. However, PI3K inhibitor wortmannin canceled the beneficial effects of adipolin on LPS-induced ARDS, as evidenced by aggravated lung injury, increased levels of W/D weight ratio, protein levels, cell counts, MPO activity, and IL-1β and TNF-α levels in the BALF(P<0.05), and decreased levels of AFC, α-ENaC and p-Akt in the lung tissues. CONCLUSION: Adipolin protects against LPS-induced ARDS in the mice by up-regulating α-ENaC and enhancing AFC via PI3K/Akt signal pathway.