基于HIF-1α/VEGF轴探讨孕前PM2.5暴露对小鼠母胎界面血管重构的影响
Effects of pre-pregnancy PM2.5 exposure on vascular remodeling in mother-fetal interface of mice via HIF-1α/VEGF axis
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摘要:
背景 大气细颗粒物（PM2.5）可引起胚胎早期发育异常，导致胚胎停育、自然流产等不良妊娠结局。低氧诱导因子-1α（HIF-1α）/血管内皮生长因子（VEGF）轴调控的母胎界面血管重构是胚胎早期发育的关键环节。
目的 观察孕前PM2.5暴露对小鼠受孕前子宫状态和受孕后母胎界面血管重构的影响，并探讨HIF-1α/VEGF轴在其中的调控作用。
方法 选取8周龄性成熟C57BL/6J小鼠雌性40只，雄性若干（交配使用，不做任何处理），适应性饲养1周。将雌鼠分为PM2.5暴露组和对照组，每组20只。PM2.5暴露组小鼠给予鼻腔滴注3 mg·kg−1的PM2.5悬液，隔天1次，持续4周；对照组给予同等剂量经空白采样膜处理的悬液。染毒期间每周记录雌鼠体重。染毒结束后每组各取6只雌鼠断头处死，取子宫称重并计算其脏器系数，利用HE染色观察子宫组织病理学形态，同时检测HIF-1α、VEGF及其受体Flt-1和Flk-1的mRNA表达。将各组剩余14只雌鼠按照雌雄2∶1合笼过夜，统计受孕比例。妊娠第10天（GD10）断头处死，解剖子宫，利用HE染色观察胚胎和胎盘组织病理学形态，同时检测母胎界面血管生成分子标志物HIF-1α、VEGF及其受体Flt-1和Flk-1的mRNA表达。
结果 与对照组相比，孕前PM2.5暴露对雌鼠体重增长无明显影响，但可引起子宫脏器系数降低，同时伴随有子宫内膜变薄等病理学损伤，以及HIF-1α、VEGF及其受体Flt-1和Flk-1的mRNA表达下降（均P＜0.05）。孕前PM2.5的暴露进一步引起雌鼠出现受孕比例降低（对照组：9/14；暴露组：5/14），胚胎排列不齐，发育异常，胎盘变小，螺旋动脉血管管壁变薄（对照组：1.00±0.06；暴露组：0.86±0.08；P=0.01）等病理学变化，HIF-1α、VEGF及其受体Flk-1的mRNA表达明显下降（均P<0.05）。
结论 孕前PM2.5暴露可引起雌鼠子宫病理学损伤和血管生成异常，进一步影响受孕后母胎界面的血管重构，HIF-1α/VEGF轴可能发挥调控作用。
Abstract:Background Atmospheric fine particulate matter (PM2.5) can induce abnormal early embryo development, resulting in adverse pregnancy outcomes such as embryo damage and spontaneous abortion. The vascular remodeling of maternal-fetal interface regulated by hypoxia inducible factor-1α (HIF-1α)/vascular endothelial growth factor (VEGF) axis is a key link in early embryo development.
Objective To investigate the effects of pre-pregnancy PM2.5 exposure on the uterine state of mice before conception and the vascular remodeling of maternal-fetal interface after conception, and to further explore the regulatory role of the HIF-1α/VEGF axis.
Methods Forty eight-week-old C57BL/6J sexually mature female mice and several males (for mating, without any treatment) were adaptive fed for 1 week. The female mice were divided into a PM2.5 exposure group and a control group, 20 mice per group. The PM2.5 exposure group was given 3 mg·kg−1 PM2.5 suspension by nasal instillation, once every other day for four weeks; the control group were treated with the same dose of blank sampling membrane suspension. Body weight of the mice was recorded every week during the experimental period. At the end of the exposure, six mice from each group were sacrificed. Then the uterus was weighted and its organ coefficients were calculated, a histopathological morphology evaluation was conducted by HE staining, and the mRNA expressions of HIF-1α, VEGF and its receptors Flt-1 and Flk-1 in the uterus samples were further examined. The remaining 14 female mice in each group were caged with male mice overnight with a sex ratio of 2:1, then we calculated the pregnancy rate. On gestation day 10 (GD10), the female mice were decapitated and the uterus was dissected, the histopathological morphology of embryo and placenta were observed by HE staining, and the mRNA expressions of HIF-1α, VEGF and its receptors Flt-1 and Flk-1 were detected as well in the uterus samples.
Results Compared with the control group, the pre-pregnancy PM2.5 exposure had no significant effect on body weight gain of the female mice, but decreased uterine organ coefficient, accompanied by pathological damage such as endometrium thinning as well as decreased mRNA expressions of HIF-1α, VEGF and its receptors Flt-1 and Flk-1 (all Ps<0.05). After mating, the pre-pregnancy PM2.5 exposure induced a decrease of the pregnancy rate (control group: 9/14; exposure group: 5/14) and abnormal embryo arrangement, small placenta, narrowing of spiral arteries (control group: 1.00±0.06; exposure group: 0.86±0.08; P=0.01), as well as significant decreases in HIF-1α, VEGF and its receptor Flk-1 mRNA expressions. (all Ps <0.05).
Conclusion Pre-pregnancy PM2.5 exposure has adverse effects on the pathological structure and angiogenesis in female mice uterus, leading to abnormal vascular network remodeling at the mother-fetal interface after conception, and the HIF-1α/VEGF axis may play a regulatory role.
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