琥珀酸通过IL-1β通路调节滋养细胞侵袭的功能及机制研究

The moderate invasiveness of trophoblasts is critical for maintaining the normal pregnancy. Nevertheless, the molecular mechanisms of the maintenance of trophoblast invasion homeostasis in early pregnancy, especially roles of metabolic pathways in this process, are largely unknown. Our preliminary study showed the amount of succinate dehydrogenase B (SDHB) was low and succinate was accumulated in human trophoblasts from normal early pregnancy. In vitro experiments demonstrated that the expression of IL-1β was up-regulated by SDHB-succinate metabolic pathway, thus, trophoblast invasion was promoted. Based on these, we intent to further explore the regulation mechanism of SDHB and succinate at maternal-fetal interface; to investigate the molecular mechanism of increased trophoblast invasion by modulating IL-1β through the SDHB-succinate metabolic pathway; and to analyze the pathogenesis of trophoblast-dysfunction-induced abortion caused by SDHB-succinate metabolic abnormalities by in vivo and in vitro experiments. This will not only contribute to the understanding of the establishment of trophoblast invasion homeostasis in the first trimester in terms of metabolism, but also potentially provide theoretical basis for clinical prevention and treatment for recurrent spontaneous abortion (RSA).

滋养细胞适度侵润是正常妊娠得以维持的关键，然而维持早孕期滋养细胞侵袭行为稳态的分子机制，尤其代谢通路在该调节过程的作用和机制亟待阐明。我们新近研究发现，正常早孕滋养细胞中存在低水平琥珀酸脱氢酶B（SDHB）及琥珀酸累积。体外实验显示SDHB-琥珀酸代谢通路促进滋养细胞分泌IL-1β，并增强其侵袭力。然而确切的分子机制尚不清楚。本项目通过构建体外细胞共培养体系以及借助基因敲除小鼠和自然流产小鼠模型等体内实验，首先阐明早孕期母-胎界面独特生殖内分泌免疫微环境对SDHB和琥珀酸的调控机制；其次深入分析SDHB-琥珀酸代谢通路通过调节IL-1β产生促进滋养细胞侵袭的分子机制；最后解析SDHB-琥珀酸代谢异常引发的滋养细胞功能异常致自然流产的病理机制。这项研究不但有助于从代谢角度解析早孕期母-胎界面滋养细胞侵袭行为稳态的形成机制，并有望为滋养细胞功能异常相关性疾病如自然流产的临床防治提供科学依据。

绒毛外滋养层细胞侵袭和增殖的失调增加了复发性自然流产（RSA）的风险，但其机制尚不清楚。在此，我们发现RSA患者的绒毛样本中琥珀酸脱氢酶复合物铁硫亚基（SDHB）的DNA甲基化水平降低，SDHB的表达升高，琥珀酸水平降低，表明低琥珀酸水平与RSA相关。在正常绒毛中，SDHB DNA甲基化从妊娠的早期至晚期持续降低，SDHB表达增加，琥珀酸水平下降。该结果表明妊娠早期高水平的SDHB DNA甲基化，SDHB表达的降低，以及高琥珀酸水平与胚胎着床成功相关。进一步研究发现，SDHB启动子甲基化招募MBD1并排除c-Fos，使SDHB表达失活并引起细胞内琥珀酸积累，通过PHD2-VHL-Hif-1α途径模拟绒毛外滋养层缺氧；然而，低琥珀酸水平逆转了这种效应并增加了RSA的风险。这项研究揭示了表观遗传失调引起的异常代谢物水平抑制了绒毛外滋养层功能，并强调了RSA干预的方法。