绒毛外滋养细胞mHLA-G唾液酸修饰影响dNK调节妊娠免疫耐受的分子机制

The recognition of mHLA-G (membrane-human leucocyte antigen-G) on the extravillous trophoblast (EVT) and the specific receptor on uterine decidual natural killer cells (dNK) is a key event in the establishment and maintenance of early pregnancy, however, the mechanism still remains unknown. Sialic acid is the terminal sugar molecule of the modified sugar chain, which recognise and bind Siglecs (sialic acid binding immunoglobulin like lectin) on the immunocyte. In our recent findings, we confirmed that sialic acid modification of trophoblast cells regulated the mouse embryo implantation by binding Siglec-E, moreover, rich sialic acid on human mHLA-G and Siglec-7 expression on human dNK were found in the early pregnancy. Accordingly, we proposed our hypothesis: the combination of mHLA-G and Siglecs can affect the invasion of EVT and the cytotoxicity of dNK by mHLA-G sialylation, and then attribute to the embryo implantation failure.In this study, we plan to explore the signal transduction mechanism of the EVT invasion ability (MAPK) and dNK cytotoxicity (SHP1/2) mediating by mHLA-G sialylation using glycan analysis and reproductive research technique, focusing on recognition effect of mHLA-G and Siglecs. And try to investigate the potential role of mHLA-G sialylation in human unexplained spontaneous abortion. Based on our study, hope it might benefit to learn more about the “cross-talk” between EVT and dNK contributing to embryo implantation and understand the effect and mechanism of glycan involved in maternal-fetal immunotolerance.

绒毛外滋养细胞（EVT）的mHLA-G与dNK受体的识别效应是妊娠建立和维持的关键事件，但机理尚不明了。唾液酸是糖基化修饰的最末端糖分子，通过特异性识别Siglecs发挥免疫效应。我们新近的发现证实：滋养细胞唾液酸修饰通过与Siglec-E的结合调控小鼠的胚胎植入，人mHLA-G唾液酸丰富及Siglec-7表达于早孕期dNK。基于此，提出实验假说：唾液酸化mHLA-G与Siglecs的结合影响其自身浸润能力和dNK细胞毒性导致胚胎植入失败而引起自然流产。本课题拟聚焦于mHLA-G唾液酸修饰的模式与调控，以EVT的浸润能力和dNK细胞毒性信号转导调节机理为主线，探讨mHLA-G与Siglecs识别影响EVT和dNK功能效应，进而初探与不明原因性自然流产的相关性。旨在为mHLA-G参与滋养细胞和dNK的“交互对话”机理展示新的研究视角，丰富糖分子参与母胎免疫耐受生理与疾病的效应与机制。

滋养层细胞功能及其膜蛋白表达与妊娠丢失密切相关。细胞及膜蛋白异常唾液酸化修饰被认为是疾病的常见标志。唾液酸化修饰在母胎界面如何参与胚胎植入及母胎免疫逃逸的机制尚未明确。本研究首先验证了绒毛外滋养层细胞（EVT）及其膜蛋白HLA-G存在丰富的唾液酸化修饰。EVT去唾液酸化修饰显著抑制细胞增殖、黏附、迁移和侵袭能力。蜕膜自然杀伤细胞(dNK)细胞表达唾液酸结合免疫球蛋白样凝集素Siglec7，及其表达升高与妊娠丢失明显相关。dNK细胞Siglec7能通过识别唾液酸，调控滋养层细胞的功能.同时dNK细胞Siglec7能也通过EVT唾液酸识别参与母胎界面免疫逃逸的建立。通过生物信息学分析我们进一步分析参与唾液酸识别相关的差异基因，结果提示Siglec1和Siglec3等分子唾液酸识别相关差异蛋白可能也参与EVT-dNK间唾液酸识别介导的母胎对话及免疫逃逸。课题的研究阐述了唾液酸化修饰参与母胎界面对话的分子机制，为不明原因性自然流产拓展新的病因学探寻了新视角。