子宫CD49a+PBX1+ trNK细胞促进胚胎早期发育

In the first trimester, tissue-resident NK (trNK) cells are the main immune cells at the maternal-fetal interface. We have demonstrated that uterine trNK cells have important physiological functions that can secrete various growth factors to promote fetal development (Immunity, 2017). In this study, we will focus on the transcriptional regulation mechanism of uterine trNK cell function by transcriptome sequencing to screen key transcription factors, ChIP-Seq to prove the regulatory mechanism, and whole exome sequencing to identify pathogenic mutation sites. Pbx1 conditional knockout mouse pregnancy models and Pbx1 point mutant mouse pregnancy model and uterine decidual specimens of patients with unexplained recurrent spontaneous abortion (URSA) were investigated to explore key transcription factors and their correlation with disease. This study will identify PBX1 as a key transcription factor driving the expression of growth factors in uterine trNK cells. It will define uterine CD49a+PBX1+ trNK cells promotes early development of fetal skeletal and nervous system, and reveal that abnormal gene expression of PBX1 in uterine trNK cells is closely related to recurrent spontaneous abortion. Based on uterine CD49a+PBX1+ trNK cells, new ideas for the diagnosis and treatment of female pregnancy disorders such as recurrent spontaneous abortion will be provided.

孕早期，母胎界面子宫组织居留trNK细胞是主体免疫细胞，我们已经阐明子宫trNK细胞分泌多种生长因子促进胚胎早期发育的重要生理功能（Immunity, 2017）。本课题我们将针对调控子宫trNK细胞功能的转录调控机制问题，采用转录组测序筛选关键转录因子，ChIP-Seq证明调控机制，全外显子测序鉴定致病突变位点等方法，结合NK细胞Pbx1条件型敲除小鼠和Pbx1点突变小鼠妊娠模型及不明原因复发性流产患者子宫蜕膜标本进行机制研究，探索关键转录因子及其与疾病的相关性，将鉴定PBX1是驱动子宫trNK细胞生长因子表达的关键转录因子，界定子宫CD49a+PBX1+ trNK细胞促进胚胎骨骼和神经系统早期发育，揭示子宫trNK细胞PBX1基因表达异常与复发性流产密切相关，为基于子宫CD49a+PBX1+ trNK细胞开展复发性流产等女性妊娠障碍疾病的诊断和治疗提供新思路。

妊娠早期，母胎界面蜕膜组织中NK细胞迅速增加，可达约占淋巴细胞总量的70%。我们先前研究已报道蜕膜NK细胞具有产生生长因子促进胚胎发育的重要功能（Immunity,2017）。然而，调控蜕膜NK细胞产生生长因子促进胚胎发育的关键转录因子及分子机制尚不清楚，与不明原因复发性流产病因相关性也有待进一步探讨。依托该项目，本研究通过全基因筛选并结合蜕膜NK细胞亚群分析，鉴定转录因子PBX1在产生生长因子的蜕膜NK细胞亚群中高表达。发现胚胎来源的HLA-G信号可以通过蜕膜NK细胞表面ILT2分子激活蜕膜NK细胞PI3K-AKT信号通路驱动PBX1的表达。证明转录因子PBX1可以直接结合生长因子PTN和OGN的启动子，增强其转录表达。提示不明原因复发性流产患者蜕膜NK细胞中，存在PBX1G21S功能性突变，利用小鼠模型进一步确认蜕膜NK细胞PBX1功能异常与不明原因复发性流产病因存在相关性。此外，我们发现在模式动物小鼠中，转录因子PBX1也具有启动Nfil3转录，促进NK细胞定向发育分化的功能。本项目鉴定了生理状态下调控人蜕膜NK细胞产生生长因子的关键转录因子PBX1，阐释PBX1的上、下游分子调控机制，揭示了CD49a+PBX1+ 蜕膜NK细胞为孕早期产生生长因子促进胚胎发育的蜕膜NK细胞功能亚群；也为临床不明原因复发性流产疾病诊断和治疗提供新靶点、新策略。. 本项目研究成果分别在Science Translational Medicine、The FASEB Journal、Frontiers in Immunology期刊发表，揭示了一种蜕膜NK细胞促进胚胎发育的转录调控新机制，为基于蜕膜NK细胞的生殖相关疾病免疫治疗提供了新思路与新靶标；且已获1项国家发明专利授权：“一种抗人PBX1单克隆抗体，其制备方法及其在复发性流产临床诊断中的用途” （专利号：ZL201910037029.X）。