Modeling human trophoblast-NK cell interactions in term and preterm birth

人类胎盘是一种半同种异体组织，其生长和发育需要母体免疫系统的耐受。胎盘细胞与母体血液和子宫组织密切接触，但在正常妊娠过程中能够逃避免疫识别。母体免疫系统在怀孕期间面临着一个挑战：保持对外来胎儿同种异体抗原的耐受性，同时在母胎界面对潜在病原体做出反应。胎盘细胞逃避母体免疫识别的机制知之甚少，特别是在人类妊娠的背景下。子宫内膜，称为蜕膜，是一个特别未被充分研究和重要的微环境，因为它是胎盘细胞绒毛外滋养层（EVT）与母体免疫细胞密切接触的界面，其中蜕膜自然杀伤（dNK）细胞是最丰富的。EVT是高度侵袭性细胞，其是母体子宫内膜的适当重塑所需的，包括导致建立母体血流至胎盘的血管重塑。已知胎盘EVT和蜕膜白细胞之间的相互作用促进EVT引起的母体血管重塑，并限制EVT侵入子宫壁的程度。事实上，早产问题可能是由dNK细胞的不当反应引起的。不幸的是，dNK和滋养层细胞之间的相互作用很难在正在进行的妊娠中研究，由于缺乏进入蜕膜室，这些重要的相互作用发生。虽然动物模型为这些过程提供了一些见解，但它们并不能准确地模拟人类胎盘形成和妊娠。该提案旨在以系统、详细的方式评估足月和早产中的蜕膜细胞群，然后将这些知识与再生医学的最新技术联合收割机结合，以开发用于研究dNK-EVT相互作用的体外模型。在过去的几年里，我们的合作研究团队已经建立了将多能干细胞分化为NK细胞和EVT的优化方法。我们现在建议产生匹配的母体和胎盘诱导多能干细胞（iPSC），并将这些细胞分别分化为dNK细胞和EVT，以模拟这两种细胞类型之间的相互作用。该提案的成功完成将建立一个可重复和可操作的模型系统，用于研究胎盘和母体免疫系统之间的相互作用，并有可能导致识别这些相互作用中的异常增加特发性自发性早产风险的机制。

The human placenta is a semi-allogeneic tissue whose growth and development requires tolerance by the maternal immune system. Placental cells come in close contact with maternal blood and uterine tissues yet are able to evade immune recognition during the course of a normal pregnancy. The maternal immune system faces a challenge during pregnancy: to maintain tolerance toward foreign fetal alloantigens while simultaneously staging a response to potential pathogens at the maternal-fetal interface. The mechanisms through which placental cells evade maternal immune recognition are poorly understood, particularly in the context of human pregnancy. The uterine lining, called decidua, is a particularly understudied and important microenvironment, because it is the interface where placental cells called extravillous trophoblast (EVT) come in close contact with maternal immune cells, of which decidual natural killer (dNK) cells are the most abundant. EVT are highly invasive cells which are required for proper remodeling of the maternal uterine lining, including vascular remodeling which leads to establishment of maternal blood flow to the placenta. Interactions between placental EVT and decidual leukocytes are known to facilitate maternal vascular remodeling by EVT and limit the extent of EVT invasion into the uterine wall. Indeed, problems in preterm birth could result from inappropriate responses by dNK cells. Unfortunately, interactions between dNK and trophoblasts are difficult to study in an ongoing pregnancy, due to lack of access to the decidual compartment, where these important interactions occur. While animal models have offered some insights into these processes, they do not accurately model human placentation and pregnancy. This proposal aims to evaluate the decidual cell population in both term and preterm birth in a systematic, detailed manner, then to combine this knowledge with the latest technologies in regenerative medicine in order to develop in vitro models for the study of dNK-EVT interactions. Over the past few years, our collaborative team of investigators has established optimized methods for differentiation of pluripotent stem cells into both NK cells and EVT. We now propose to generate matched maternal and placental induced pluripotent stem cells (iPSC), and differentiate these cells into dNK cells and EVT, respectively, in order to model interactions between these two cell types. Successful completion of this proposal will establish a reproducible and manipulatable model system for studying interactions between the placenta and maternal immune system and has the potential to lead to identification of mechanisms through which abnormalities in these interactions increase the risk of idiopathic spontaneous preterm birth.