ATP与胚胎着床及蜕膜化的关系

Embryo implantation is a key step for establishing pregnancy. Among the pregnancy loss, 75% is caused by implantation failure. It is known that decidual reaction can be induced by oil injection or mechanical stretch of uterine lumen. For assisted reproduction, local endometrial injury during the previous cycle is beneficial for increasing pregnancy rate. However, the underlying mechanism is still not clear. Recent data suggest that human corneal or tracheal epithelium can release a large amount of ATP under the stimulation of mechanical damage, stretch or inflammation. The released ATP can activate many implantation-related genes, including COX-2, Egr1, p-Stat3 and cPLA2. Our preliminary data also showed that there is a high level of ATP in preimplantation blastocysts and uterine fluid. We assume that ATP released from blastocyst or damaged uterine epithelium may play a key role during embryo implantation and decidualization. We will use mouse models in vivo and in vitro, and human endometrial cell lines to analyze the effects of ATP on uterine receptivity, decidualization, muscular contraction and epithelium-stromal interaction. This study will characterize the regulation and function of released ATP from embryos and damaged uterine epithelium during embryo implantation and decidualization. Data from this study will shed lights on understanding the mechanism of embryo implantation and decidualization.

胚胎着床是妊娠建立的关键步骤。在妊娠损失中，75%是由着床失败导致的。已知在小鼠子宫腔中注射油滴或者搔刮等机械刺激可引起蜕膜化反应。在卵巢刺激的前一个周期，对人子宫内膜进行局部损伤，有助于提高妊娠率，但其机理一直不清楚。最近研究表明，人角膜及支气管上皮等受到机械损伤等刺激后可释放大量的ATP，这些ATP可激活COX-2、Egr1、p-Stat3及cPLA2等胚胎着床相关分子。我们的前期结果证实着床期胚胎及子宫腔中含有高水平的ATP，推测胚胎或受损子宫上皮释放的ATP可能在胚胎着床及蜕膜化中起重要作用。我们拟以小鼠体内及体外模型以及人子宫内膜细胞系为材料，通过机械损伤、升高或降低ATP浓度及ATP受体抑制剂处理等手段，分析ATP与子宫接受性、蜕膜化、肌肉收缩以及上皮-基质对话等关系，明确胚胎或受损子宫上皮释放的ATP在胚胎着床及蜕膜化中的调节与功能。本项目将有助于了解胚胎着床和蜕膜化的机理。

胚胎着床是哺乳动物妊娠建立过程中一个十分重要的环节，是发育到胚泡期的胚胎和处于接受状态的子宫之间建立通讯联系的过程。虽然，已证实应激及损伤等引起的无菌炎症参与很多生理及病理过程，但这些无菌炎症与胚胎着床及蜕膜化的关系仍不清楚。本课题利用小鼠和体外培养的人子宫上皮细胞和基质细胞对于无菌炎症相关分子ATP在小鼠及人胚胎着床及蜕膜化过程中的调节及功能进行了详细研究。我们证实：（1）胚泡来源的乳酸刺激子宫上皮释放ATP进而诱导基质细胞的蜕膜化过程。人子宫内膜上皮细胞损伤后可迅速释放ATP到细胞外环境中。胚泡来源的乳酸可诱导非损伤性的子宫内膜上皮细胞通过间隙链接蛋白释放ATP。释放到细胞外的ATP可刺激上皮细胞释放细胞因子IL-8去诱导基质细胞的蜕膜化过程。细胞外的ATP也可直接与基质细胞上的P2Y受体结合后诱导蜕膜化过程。我们也证实，体外培养的子宫上皮细胞损伤后的上清液可显著促进体外蜕膜化过程。（2）ATP介导小鼠的胚胎着床及蜕膜化过程。小鼠子宫腔液中ATP的浓度增加依赖于胚胎的存在。胚泡来源的乳酸可刺激接受态上皮释放ATP。着床前期子宫上皮中表达ATP的受体P2Y2，并在妊娠第5天胚胎周围的基质细胞中显著上调。抑制P2Y2可显著阻止胚胎着床和蜕膜化过程。细胞外的ATP与受体P2Y2结合后，可能通过磷酸化上皮中的Stat3及上调基质细胞中的EGR1和COX-2来调节胚胎着床及蜕膜化过程。高浓度的ATP可在短时间内促进蜕膜化过程。蜕膜细胞中高表达的外核苷酸酶可很快水解ATP，以免细胞长时间暴露于高浓度的ATP中。本课题共发表SCI论文8篇，培养5名博士生和5名硕士生。已经完成计划任务书中所要求的各项研究任务。