FETAL CMV INFECTION: ROLE OF THE HUMAN PLACENTA

胎儿 CMV 感染：人胎盘的作用

• 批准号: 6497306
• 负责人: LENORE PALMA PEREIRA
• 金额: $ 27.31万
• 依托单位: UNIVERSITY OF CALIFORNIA, SAN FRANCISCO
• 依托单位国家: 美国
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-02-01 至 2005-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6497306
• 关键词: Herpesviridae disease; cell differentiation; cell migration; clinical research; cytomegalovirus; female; human pregnant subject; human tissue; placenta; placental transfer; pregnancy infection; trophoblast; vertical transmission; virus genetics; virus infection mechanism

Human cytomegalovirus (CMV) infection of the embryo/fetus is the leading cause of congenital viral infection. It occurs in 1 percent of live births in the United States. The consequences include poor neurologic development, visual impairment, and sensorineural hearing loss. Placentas from women with congenital CMV who abort spontaneously (15 percent) show evidence of infection without fetal involvement, indicating that placental infection precedes virus transmission to the fetus. Successful pregnancy depends on normal placental development, a stepwise process that involves differentiation of the organ's epithelial stem cells, termed cytotrophoblasts (CTBs). CTBs differentiate via two pathways into villi that either anchor the placenta to the uterine wall or float in maternal blood. In the first pathway, CTBs in anchoring villi switch on expression of adhesion receptors and proteinases that are needed for invasion of maternal arteries, as well as immune molecules that elicit maternal tolerance. Our studies showed that CMV infection of first trimester differentiating/invading CTBs in vitro downregulates expression of two functionally important stage-specific antigens nonclassical MHC class Ib HLA-G and integrin alpha1beta1. Moreover, the invasion competence of infected CTBs in vitro was dramatically impaired as was the 2invasiveness of CTBs isolated from a placenta infected with CMV in vivo. This correlation between impaired invasion and disregulation of alpha1beta1 suggests that faulty invasion of maternal arteries may be a hallmark of CMV-infected placentas. In the second pathway, CTBs fuse to form syncytiotrophoblasts (STBs) that cover floating villi. When floating villi were exposed to CMV in vitro, STBs were uninfected and the underlying CTB stem cells were infected. This unexpected result suggested that STBs transmit virus from maternal blood, bathing their surface, to the CTB stem cells adjacent to the villus core. Non-neutralizing anti-viral IgG in primary infection may enhance transcytosis of IgG-coated virions. It is hypothesized that CMV is transmitted from the mother to the placenta and the embryo/fetus by infection of CTB stem cells in floating villi, following transcytosis across the STB barrier, and by infection of invasive CTBs within the uterine wall. The specific aims are: (1) Determine the effects of CMV infection on CTB invasiveness and immune function in vitro and then establish relevance in vivo. 2) Identify/map CMV genes involved in disregulating CTB differentiation/invasion and immune function. (3) Determine whether infection of underlying CTB stem cells near the villus stromal core occurs by transcytosis of IgG-coated CMV virions across the surface layer of STBs in vitro and then establish relevance in vivo. These experiments will advance our knowledge of the role of the placenta in pregnancy complications due to CMV infection, a critical issue in prenatal development. The results could offer the first molecular evidence regarding the route of transmission and lead to strategies to prevent infection of the fetus.

胚胎/胎儿的人类巨细胞病毒（CMV）感染是先天性病毒感染的主要原因。 它发生在美国的1％的活产。 后果包括神经系统发育不良，视觉障碍和感觉性听力损失。 先天性CMV女性的胎盘自发流产（15％）显示出没有胎儿参与的感染的证据，这表明胎盘感染先于病毒传播到胎儿。 成功的妊娠取决于正常的胎盘发育，这是一个涉及器官上皮干细胞的分化的逐步过程，称为细胞增生细胞（CTBS）。 CTBS通过两种途径分化为将胎盘固定在子宫壁上的绒毛，或者在母血中浮动。 在第一个途径中，锚定绒毛的CTB在锚定的粘附受体和蛋白酶的表达中，这是侵袭母体动脉所需的，以及引起母体耐受性的免疫分子。 我们的研究表明，在体外，CMV感染了头三生/入侵CTB的CMV感染可下调两个功能上重要的阶段特异性抗原非经典MHC类IB HLA-G和整合素α1Beta1的表达。 此外，受感染的CTB在体外的侵袭能力受到了巨大的损害，而从体内感染CMV的胎盘中分离出的CTB的2个侵蚀性也受到了损害。 侵袭与α1BETA1的侵袭受损之间的这种相关性表明，孕产妇动脉的侵袭可能是CMV感染的胎盘的标志。在第二个途径中，CTBS融合形成覆盖浮动绒毛的合成素细胞（STB）。 当漂浮的绒毛在体外暴露于CMV时，未感染STB，并感染下面的CTB干细胞。 这种意外的结果表明，STB将病毒从母体血液（将其表面沐浴）传播到与绒毛核心相邻的CTB干细胞。原发性感染中的非中和抗病毒IgG可能会增强IgG涂层病毒体的转换。 假设CMV是通过浮动绒毛中CTB干细胞感染的CMV向胎盘和胚胎/胎儿传播的，在跨STB屏障的转胞膜后以及子宫壁中的侵入性CTB感染后。 具体目的是：（1）确定CMV感染对CTB侵袭性和体外免疫功能的影响，然后在体内建立相关性。 2）识别/MAP CMV基因无视CTB分化/侵袭和免疫功能。 （3）确定是否通过在体外整个STB的表面跨膜片上胞胞菌的脑膜胞膜来发生感染绒毛基质芯附近的基础CTB干细胞的感染，然后在体内建立相关性。 这些实验将促进我们对胎盘在CMV感染引起的妊娠并发症中的作用的了解，这是产前发育中的关键问题。 结果可以提供有关传播途径的第一个分子证据，并导致防止胎儿感染的策略。