Autoimmune Regulator gene (Aire)-mediated tolerance to pregnancy-associated self-antigens

项目总结 胎儿和胎盘如何避免母体免疫系统的排斥反应的问题一直令人困惑。 几代免疫学家和生殖生物学家。关于这一免疫学悖论的大量工作 专注于母体免疫系统如何耐受胎儿同种异体抗原的问题。然而，另一个 怀孕期间的问题导致母亲暴露在许多新诱导的或强烈的 由母亲自己的基因组编码的上调的自身抗原。其中许多“与怀孕有关” 抗原“(Paas)自从母亲自己是一个有胎盘的胎儿以来就没有产生过，并且只有 在出生后的生活中遇到的当她怀孕时。将宽容强加给自我的一个重要组成部分 抗原是自身免疫调节基因(Aire)，它促进组织限制性抗原的表达 在髓质胸腺上皮细胞(MTECs)和胸腺外细胞(ETACs)中，Aire表达细胞(ETACs)导致 自身反应性T细胞的克隆性缺失或Treg转化。Aire在支持健康怀孕方面的作用有 还没有被探索过。令人惊讶的是，我们发现选择性地耗尽小鼠体内表达Aire的母体细胞 在怀孕早期导致显著的妊娠丢失表型(两者均未受孕 在堵塞和早期胚胎吸收后)，伴随着常规T细胞向Treg的显著增加 胸腺中的细胞比率和母体T细胞流入吸收子宫。这些数据是一致的 与文献中的其他提示，如抗胎盘抗体的存在和妊娠并发症 (如胎盘功能不全)Aire缺乏症患者。根据这些数据，我们假设 AIRE介导的PaaS在mTECs和eTACs中的表达通过促进基因缺失来支持健康妊娠 PAA反应性T细胞和PAA特异性Tregs的诱导。进一步说，对这些抗原的免疫反应 在缺乏Aire的情况下，可能在妊娠并发症中发挥作用。这一假设改变了当前的范式 关于母胎耐受从关注同种异体抗原的潜在威胁到未知的潜在威胁 对母体基因组编码的一组独特的PaaS施加耐受性的价值。在这项提案中，我们将 首先评估Aire在妊娠早期和晚期的时间作用，以及mTECs和mTECs的相对贡献 ETAC在支持健康妊娠方面的作用(目标1)。我们将使用无偏见的生化和 转录分析鉴定Aire调控的PaaS并验证其在小鼠和 不孕症患者(目标2)。最后，我们将研究Aire在生成PAA特定树中的功能 利用新型转基因小鼠在母体mTECs中表达Aire调控的模型抗原 ETAC(目标3)。我们的短期目标是了解Aire支持健康的机制 怀孕了。我们的长期目标是确定不孕症患者中特定的PaaS和免疫紊乱。 对这些问题的回答可以提供关键的见解，从而为这一重要的疾病提供有针对性的治疗 健康问题。

PROJECT SUMMARY The question of how the fetus and placenta avoid rejection by the maternal immune system has puzzled generations of immunologists and reproductive biologists. A great deal of work on this immunological paradox has focused on the problem of how the maternal immune system tolerates fetal alloantigens. However, another problem during pregnancy entails the exposure of the mother to numerous newly-induced or strongly upregulated self-antigens encoded by the mother’s own genome. Many of these “pregnancy associated antigens” (PAAs) have not been produced since the mother herself was a fetus with a placenta and are only encountered in postnatal life when she becomes pregnant. A crucial component in imposing tolerance to self- antigens is the autoimmune regulator gene (Aire), which promotes the expression of tissue-restricted antigens in medullary thymic epithelial cells (mTECs) and extrathymic cells Aire expressing cells (eTACs), leading to clonal deletion or Treg conversion of self-reactive T cells. The role of Aire in supporting healthy pregnancy has not yet been explored. Surprisingly, we found that selective depletion of maternal Aire-expressing cells in mice during early in pregnancy results in a dramatic phenotype of pregnancy loss (both failure to become pregnant after plugging and early embryo resorption), along with a significant increase in the conventional T cell to Treg cell ratio in the thymus and an influx of maternal T cells into the resorbing uterus. These data are consistent with other hints in the literature such as the presence of anti-placental antibodies and pregnancy complications (such as fetoplacental insufficiency) in patients with Aire deficiency. Based on these data, we hypothesize that Aire-mediated expression of PAAs in mTECs and eTACs supports healthy pregnancy by promoting deletion of PAA-reactive T cells and induction of PAA-specific Tregs. By extension, immune responses to these antigens in the absence of Aire may play a role in pregnancy complications. This hypothesis shifts the current paradigm regarding maternal-fetal tolerance from focusing on the potential threat of alloantigens to the unknown potential value of imposing tolerance to a unique set of PAAs encoded by the maternal genome. In this proposal, we will first assess the temporal role of Aire during early vs late pregnancy and the relative contributions of mTECs vs eTACs in supporting healthy pregnancy (Aim 1). We will use a combination of unbiased biochemical and transcriptomic analyses to identify putative Aire-regulated PAAs and validate their expression in mice and in patients with infertility (Aim 2). Lastly, we will investigate the function of Aire in generating PAA-specific Tregs using a novel transgenic mouse to express a model antigen under the control of Aire in maternal mTECs and eTACs (Aim 3). Our short-term goal is to understand the mechanisms by which Aire supports healthy pregnancy. Our long-term goal is to identify specific PAAs and immune derangements in patients with infertility. Responses to these questions could provide key insights that will lead to targeted therapies for this important health problem.