脂氧素对滋养细胞氧化损伤的保护作用及其机制

目的研究脂氧素(lipoxinA4,LXA4)在孕妇血清中的表达及其对滋养细胞氧化损伤的保护作用和作用机制.方法 细胞实验分为6组,对照组;脂多糖(lipopolysaccharides,LPS)组:10 μg/ml LPS作用24 h;干预组:10 μg/ml LPS+100 nmol/L LXA4作用24 h;LXA4组:100 nmol/L LXA4作用24 h;拮抗组:10 μg/ml LPS+100 nmol/L LXA4+100 μmol/L N-叔丁氧羰基吡咯烷(N-tert-butoxycarbonyl-2-pyrrolidine,BOC-2)作用24 h;BOC-2组:10μg/ml LPS+100 μmol/L BOC-2 作用24 h.采用酶联免疫吸附试验检测正常孕妇与子痫前期患者血清LXA4含量;以2,7-二氢二氯荧光素二乙酸酯为荧光探针检测滋养细胞内活性氧(reactive oxygen species,ROS)水平;逆转录-聚合酶链反应检测超氧化物歧化酶(superoxide dismutase,SOD) mRNA的表达;Western印迹分析SOD、转录因子NF-E2相关因子2(NF-E2-related factor,Nrf2)的蛋白表达水平;黄嘌呤氧化酶法测定滋养细胞中SOD活性.结果 (1)子痫前期患者血清LXA4水平为(165.53±18.89) pg/L,与正常孕妇(545.67±30.91) pg/L]相比明显下降(t=40.64,P<0.01).(2)LPS组与对照组相比,滋养细胞内二氯荧光素(dichlorofluorescein,DCF)密度值明显升高(P<0.01),DCF密度值从53.00±3.08 上升至77.00±5.83( t=8.14,P<0.01);胞核中Nrf2蛋白、SOD mRNA和蛋白表达均显著下降(t分别为34.11、25.61和17.93,P均<0.01);滋养细胞上清中的SOD含量明显下调(t=12.16,P<0.01).(3)干预组与LPS组相比,滋养细胞内DCF密度值明显下降,DCF密度值从77.00±5.83降至62.00±3.39(t=4.97,P<0.01),胞核中Nrf2蛋白、SOD mRNA表达显著上升(t分别为11.74和13.17,P均<0.01),SOD蛋白表达也有所升高(t=4.67,P<0.05),滋养细胞上清中的SOD含量明显增加,酶活力上升至(8.93±0.53) U/ml(t=14.76,P<0.01).(4)拮抗组与干预组相比,滋养细胞上清中SOD含量下降至(6.23±0.41) U/ml(t=9.03,P<0.01),但仍高于LPS组(t=6.10,P<0.01);BOC-2组SOD含量为(4.90±0.32) U/ml,与LPS组相比差异无统计学意义(t=0.79,P>0.05).结论 LXA4可明显减轻LPS引起的胎盘滋养细胞氧化损伤,且LXA4可通过脂氧素受体(lipoxinA4 receptor,ALX-R)激活Nrf2/抗氧化反应元件(antioxidant response element,ARE)信号通路来发挥抗氧化损伤的作用.

Abstract：

Objective To explore lipoxinA4 (LXA4) expression in maternal serum of pregnant women and the protective effect and mechanism of LXA4 on trophoblastic cells from oxidative injury. Methods Trophoblastic cells were randomized into six groups: Control group; Lipopolysaccharides (LPS) group, cells were stimulated by 10 μg/ml LPS for 24 h; Intervention group, cells stimulated by LPS were treated with 100 nmol/L LXA4 for 24 h; LXA4 group, cells were treated with 100 nmol/L LXA4 for 24 h; Antagonistic group, cells stimulated by LPS were treated with 100 nmol/L LXA4 plus 100 μmol/L N-tert-butoxycarbonyl-2-pyrrolidine (BOC-2) for 24 h; BOC-2 group, trophoblastic cells stimulated by LPS were treated with 100 μmol/L BOC-2 for 24 h. The serum concentration of LXA4 in normal group and preeclampsia group was detected by ELISA. The intracellular formation of reactive oxygen species (ROS) was detected by 2,7-dichlorofluorescein diacetate (DCFH-DA) as a fluorescent probe. SOD mRNA was analyzed by RT-PCR. SOD and Nrf2 protein expressions were analyzed by Western blot. The levels of SOD in trophoblastic cells were detected by using detection kit. Results (1) The serum concentration of LXA4 was significantly lower in preeclampsia group (165.53±18.89) pg/L than in the control (545.67±30.91) pg/L, P<0.01]. (2) Compared with control group, the levels of ROS in LPS group were significantly higher, DCF density of trophoblastic cells increased from 53.00±3.08 to 77.00±5.83 (P<0.01). The expression of nuclear Nrf2 protein, SOD mRNA and protein in LPS group were obviously decreased (P<0.01). The levels of SOD in LPS group were also significantly lower (P<0.01). (3) Compared with LPS group, the levels of ROS in intervention group were significantly lower, DCF density of trophoblastic cells decreased from 77.00±5.83 to 62.00±3.39 (P<0.01). The expression of nuclear Nrf2 protein, SOD mRNA in intervention group were obviously increased (P<0.01), so did the SOD protein expression (P<0.05). The levels of SOD were significantly increased from (4.77±0.34) U/ml to (8.93±0.53) U/ml (P<0.01). (4) The levels of SOD in antagonistic group were lower than in intervention group, but still higher than LPS group. (6.23±0.41) U/ml vs (8.93±0.53) U/ml (P<0.01) or (4.77±0.34) U/ml (P<0.01)]. No significant difference was found in the levels of SOD between BOC-2 and LPS group (P>0.05). Conclusions LXA4 can significantly reduce the oxidative stress of placental trophoblastic cells stimulated by LPS. LXA4 can bind to lipoxin receptors and activate Nrf2-ARE signaling pathway playing a protective effect. So LXA4 in pregnant women can affect the oxidative stress of placenta.

Protective effect and mechanism of lipoxinA4 on oxidative injury in trophoblastic cells

Objective To explore lipoxinA4 (LXA4) expression in maternal serum of pregnant women and the protective effect and mechanism of LXA4 on trophoblastic cells from oxidative injury. Methods Trophoblastic cells were randomized into six groups: Control group; Lipopolysaccharides (LPS) group, cells were stimulated by 10 μg/ml LPS for 24 h; Intervention group, cells stimulated by LPS were treated with 100 nmol/L LXA4 for 24 h; LXA4 group, cells were treated with 100 nmol/L LXA4 for 24 h; Antagonistic group, cells stimulated by LPS were treated with 100 nmol/L LXA4 plus 100 μmol/L N-tert-butoxycarbonyl-2-pyrrolidine (BOC-2) for 24 h; BOC-2 group, trophoblastic cells stimulated by LPS were treated with 100 μmol/L BOC-2 for 24 h. The serum concentration of LXA4 in normal group and preeclampsia group was detected by ELISA. The intracellular formation of reactive oxygen species (ROS) was detected by 2,7-dichlorofluorescein diacetate (DCFH-DA) as a fluorescent probe. SOD mRNA was analyzed by RT-PCR. SOD and Nrf2 protein expressions were analyzed by Western blot. The levels of SOD in trophoblastic cells were detected by using detection kit. Results (1) The serum concentration of LXA4 was significantly lower in preeclampsia group (165.53±18.89) pg/L than in the control (545.67±30.91) pg/L, P<0.01]. (2) Compared with control group, the levels of ROS in LPS group were significantly higher, DCF density of trophoblastic cells increased from 53.00±3.08 to 77.00±5.83 (P<0.01). The expression of nuclear Nrf2 protein, SOD mRNA and protein in LPS group were obviously decreased (P<0.01). The levels of SOD in LPS group were also significantly lower (P<0.01). (3) Compared with LPS group, the levels of ROS in intervention group were significantly lower, DCF density of trophoblastic cells decreased from 77.00±5.83 to 62.00±3.39 (P<0.01). The expression of nuclear Nrf2 protein, SOD mRNA in intervention group were obviously increased (P<0.01), so did the SOD protein expression (P<0.05). The levels of SOD were significantly increased from (4.77±0.34) U/ml to (8.93±0.53) U/ml (P<0.01). (4) The levels of SOD in antagonistic group were lower than in intervention group, but still higher than LPS group. (6.23±0.41) U/ml vs (8.93±0.53) U/ml (P<0.01) or (4.77±0.34) U/ml (P<0.01)]. No significant difference was found in the levels of SOD between BOC-2 and LPS group (P>0.05). Conclusions LXA4 can significantly reduce the oxidative stress of placental trophoblastic cells stimulated by LPS. LXA4 can bind to lipoxin receptors and activate Nrf2-ARE signaling pathway playing a protective effect. So LXA4 in pregnant women can affect the oxidative stress of placenta.