抑制胞浆型磷脂酶A2活性对内毒素诱导人脐静脉内皮细胞分泌瘦素的影响

Effect of inhibition of cytosolic phospholipase A2 on Leptin release from human umbilical vein endothelial cells induced by lipopolysaccharide

目的 通过改变胞浆型磷脂酶A2（cPLA2）的活性,检测细菌脂多糖（LPS）及Ca2＋载体A23187诱导的人脐静脉内皮细胞株（ECV-304）上清液中瘦素（Leptin）水平的变化,探讨在体外炎症状态下cPLA2活性与细胞分泌Leptin的关系.方法 体外培养ECV-304细胞.实验1：将细胞分为空白对照组,LPS 3个浓度5、10、20 μg/ml刺激组,Ca2＋载体A23187 3个浓度0.1、 1.0、10.0 μmol/L刺激组共7个组,分别作用6、12、24 h后收集上清液.实验2：根据实验1结果将细胞分为空白对照组,LPS 20 μg/ml刺激组,cPLA2特异性抑制剂AACOCF3 3个浓度0.1、1.0、10.0 μmol/L与LPS合用刺激组,丝裂素活化蛋白激酶上游激酶1/2（MEK1/2）抑制剂 U0126 3个浓度0.1、1.0、5.0 μmol/L与LPS合用刺激组共8个组,在LPS刺激前1 h加入AACOCF3或U0126,LPS刺激24 h后收集上清液.采用放射免疫分析法检测Leptin水平.结果 实验1：随LPS刺激浓度增加和时间延长,细胞释放Leptin浓度逐渐减少,LPS 20 μg/ml组作用24 h后Leptin浓度（ng/ml）较空白对照组显著下降（0.540±0.109比0.823±0.048,P〈0.05）.但A23187对细胞分泌Leptin并无显著影响.实验2：LPS刺激能使细胞分泌Leptin浓度（ng/ml）明显下降（0.558±0.069比0.825±0.067,P〈0.05）;而用不同浓度AACOCF3或U0126干预后,细胞分泌Leptin的浓度（ng/ml）有所回升,且呈浓度依赖性（AACOCF3 0.1、1.0、10.0 μmol/L组分别为0.673±0.135、 0.723±0.055、 0.797±0.062;U0126 0.1、 1.0、5.0 μmol/L组分别为0.698±0.112、 0.862±0.184、0.935±0.145）,AACOCF3 1.0 μmol/L、10.0 μmol/L组和U0126 1.0 μmol/L、5.0 μmol/L组Leptin浓度均显著高于LPS 20 μg/ml刺激组（均P〈0.05）.结论 在由LPS诱导的体外炎症状态下,Leptin的分泌与cPLA2的活性具有一定的关系.

Objective To determine Leptin levels in supernatant fluid of culture of human umbilical vein endothelial cells （ECV-304） after being challenged by lipopolysaccharide （LPS） and calcium ion vector A23187, and to explore the possible relation between Leptin release and cytosolic phospholipase A2 （cPLA2） activity in an inflammatory cell model. Methods ECV-304 cells were cultured in vitro. Experiment 1： the cells were divided into seven groups： blank control group, LPS 5, 10, 20 μg/ml stimulation groups, A23187 0.1, 1.0, 10.0 μmol/L stimulation groups. The supernatants were collected at 6, 12 and 24 hours. Experiment 2： according to the results of experiment 1, the cells were divided into eight groups： blank control group, LPS 20 μg/ml stimulation group, the inhibitor of cPLA2 AACOCF3 0.1, 1.0, 10.0 μmol/L plus LPS stimulation groups, the inhibitor of mitogen-activated protein/extracellular signal-regulated protein kinase kinase 1/2 （MEK1/2） U0126 0.1, 1.0, 5.0 μmol/L plus LPS stimulation groups, with AACOCF3 or U0126 added 1 hour before the addition of LPS, and the supernatants were collected 24 hours after the addition of LPS. Leptin level was determined by radioimmunoassay. Results Experiment 1： with increase in LPS concentration and prolongation of time, Leptin release was decreased gradually. After 24 hours of interaction the concentration of Leptin （ng/ml） in LPS 20 μg/ml group was decreased significantly compared with the blank control group （0.540±0.109 vs. 0.823±0.048, P〈0.05）. However, A23187 had no significant effect on Leptin release. Experiment 2： LPS rendered cells to release less Leptin （ng/ml： 0.558±0.069 vs. 0.825±0.067, P〈0.05）; by adding AACOCF3 or U0126 in different concentration before adding LPS rendered the cells to release more Leptin （ng/ml）, and it showed concentration-dependent （the AACOCF3 0.1, 1.0, 10.0 μmol/L groups were 0.673±0.135, 0.723±0.055, 0.797±0.062, respectively; the U0126 0.1, 1.0, 5.0 μmol/L groups were 0.698±0.112, 0.862±0.184, 0.935±0.145, respectively）. The release of Leptin in AACOCF3 1.0 μmol/L, 10.0 μmol/L and U0126 1.0 μmol/L, 5.0 μmol/L groups was significantly higher than LPS 20 μg/ml stimulation group （all P〈0.05）. Conclusion There is a possible relation between Leptin release and cPLA2 activity in inflammatory cells induced by LPS.