miR-184通过下调滋养细胞IL4I1表达调节蜕膜调节性T细胞的机制研究

Maternal-fetal immune tolerance is crucial for the maintainence of successful pregnancy, and trophoblast cells involve in regulating the differentiation of decidual immune cells. Our previous study has demonstrated that miR-184 is highly expressed in villous and decidual tissues as well as in the peripheral blood of patients with recurrent spontaneous abortion (RSA). And miR-184 promotes the apoptosis of HTR8 cells by upregulating the expression of Fas thus leading to abortion. Meanwhile, application of cell co-culture system has shown that high expression of miR-184 in HTR8 cells could suppress the differentiation of decidual regulatory T (Treg) cells notably, but the exact mechanisms are unclear. Result of RNA-Seq has suggested that the expression of IL4I1 was downregulated in HTR8 cells of miR-184 high expression , whereas IL4I1 has been confirmed to promote the differentiation of Treg cells significantly, thus we speculate that miR-184 might inhibit the differentiation of decidual Treg cells by downregulating the expression of IL4I1 in trophoblast cells. Subsequently, taking advantage of in vitro cell co-culture system and in vivo animal experiments, the current study intends to further validate the regulation role of IL4I1 in the differentiation of decidual Treg cells, and to identify the functional target genes of miR-184 in suppressing the expression of IL4I1 in trophoblast cells, thereby illuminating the immunoregulatory effect of miR-184 on the maintainence of normal pregnancy and providing a new diagnostic and therapeutic target for RSA.

母胎免疫耐受对成功妊娠的维持具有重要作用，而滋养细胞可以参与调控蜕膜免疫细胞分化。前期我们研究发现miR-184在反复自然流产患者的绒毛、蜕膜组织及外周血中表达均升高，通过上调滋养细胞表面Fas的表达促进细胞凋亡，导致流产；同时，细胞共培养体系研究发现滋养细胞miR-184高表达能显著抑制蜕膜调节性T(Treg)细胞分化，但具体机制不清。RNA-Seq提示IL4I1在miR-184过表达的滋养细胞中表达下降，而已知IL4I1能显著促进Treg细胞分化，由此推测miR-184或可下调滋养细胞IL4I1表达而抑制蜕膜Treg细胞分化。后续本课题拟通过体外细胞共培养和体内动物实验进一步验证IL4I1对蜕膜Treg细胞分化的调节作用；明确miR-184抑制滋养细胞IL4I1表达的功能性靶基因。以期阐明miR-184对正常妊娠维持的免疫调控作用，为反复自然流产的临床诊治提供新的靶点。

反复自然流产（RSA）指连续两次或两次以上的怀孕在同一妊娠周发生自然流产的现象，严重威胁人类的生殖健康。前期通过microRNA芯片分析发现miR-184在反复自然流产患者绒毛及蜕膜组织中的表达均高于正常妊娠妇女。并且，与正常妊娠妇女相比，反复自然流产患者外周血中miR-184的表达也显著增加。对miR-184过表达HTR8细胞表型分析发现，miR-184能促进滋养细胞凋亡并抑制其增殖。进一步机制研究表明miR-184通过抑制滋养细胞WIG1表达而上调Fas的表达，导致滋养细胞凋亡。最后，通过构建miR-184过表达小鼠模型研究表明miR-184过表达显著增加孕鼠的胚胎吸收率。综上所述，本研究表明miR-184对成功妊娠的维持至关重要，也为临床上反复自然流产提供了新的诊断和治疗靶点。