敲除S1PR3可缓解小鼠的急性肺损伤：基于抑制MAPK信号通路

目的 探讨敲除S1PR3是否通过抑制丝裂原活化蛋白激酶(MAPKs)途径改善脂多糖(LPS)诱导的小鼠急性肺损伤。方法 用LPS诱导小鼠急性肺损伤模型。雄性C57BL/6J和S1PR3敲除小鼠，随机分为4组：C57 NS组(C57，生理盐水处理)、C57LPS组(C57,LPS诱导)、S1PR3^-/-NS组(S1PR3敲除鼠，生理盐水处理)、S1PR3^-/-LPS组(S1PR3敲除鼠，LPS诱导)，8只/组。RT-qPCR检测S1PR3,IL-β和IL-18表达，HE染色检测肺部组织损伤，流式细胞术检测细胞凋亡水平，Western blot法检测caspase-1,GSDMD,p-JNK,p-ERK p-p38蛋白表达水平。同时，Ⅱ型肺泡上皮细胞(MLE-12细胞)铺板后分为4组：PBS组、LPS组、CYM5541组(仅加入S1PR3激动剂)、CYM5541+LPS组(加入S1PR3激动剂+LPS)，检测各组细胞焦亡水平及MAPK信号通路分子的表达水平。结果 急性肺损伤小鼠肺组织S1PR3表达上调(P<0.001)；血清IL-1β和IL...

Knockout of S1PR3 attenuates acute lung injury in mice by inhibiting the MAPK pathway

Objective To investigate whether knockout of S1PR3 improves lipopolysaccharide (LPS)-induced acute lung injury in mice by inhibiting mitogen activated protein kinases (MAPKs). Methods Male C57BL/6J and S1PR3 knockout (S1PR3-/-) mice were both randomized into two groups (n=8) for intratracheal instillation of normal saline or LPS to induce acute lung injury. The expressions of S1PR3, IL-1β and IL-18 in the lung tissues were detected using RT-qPCR, lung tissue injury was observed with HE staining, and cell apoptosis was detected using flow cytometry. Western blotting was performed to detect the expression levels of caspase-1, GSDMD, p- JNK, p-ERK and p-p38 proteins. In the cell experiment, type II alveolar epithelial cells (MLE-12 cells) were treated with PBS, LPS, CYM5541 (a S1PR3 agonist), or CYM5541 + LPS, and the cell apoptosis and expression levels of MAPK signal pathway molecules were detected. Results The expression of S1PR3 was up-regulated and serum IL-1β and IL-18 levels were elevated significantly in the nontransgenic mice with acute lung injury (P<0.001). By comparison, the elevation of IL-1β and IL-18 levels was obviously reduced in S1PR3 knockout mice with acute lung injury, which also showed significant improvement of pulmonary hemorrhage, inflammation and exudation, lowered wet-to-dry ratio of the lungs, and decreased cell apoptosis and expressions of cleaved caspase-1 and GSDMD (P<0.05). In MLE-12 cells, treatment with the S1PR3 agonist significantly increased the expression of pyroptosis-associated proteins (P<0.05). S1PR3 knockout strongly inhibited the activation of MAPKs family (JNK and ERK p38; P<0.05), but their expressions were significantly increased following treatment with the S1PR3 agonist (P<0.05). Conclusion Inhibition of S1PR3 can improve LPS-induced acute lung injury in mice by inhibiting the activation of MAPK signaling.