T cell immunity to CMV in utero and in early childhood

摘要： 宫内巨细胞病毒感染导致长期的病毒血症，往往是毁灭性的临床后遗症。在成年人中， 确定了对CMV的T细胞应答是遏制病毒血症所必需的。然而，免疫学 先天性CMV感染后病毒控制和临床后遗症的决定因素尚不清楚。在这 项目，我们将研究CMV的免疫反应，作为了解免疫个体发育和年龄相关性的窗口。 抗病毒T细胞功能的成熟。我们将利用大量的母婴配对样本， 纵向储存用于免疫学研究。这个队列，其中包括大量的婴儿感染 子宫内巨细胞病毒和儿童早期感染的其他病毒，提供了一个独特的机会来检查 年龄相关的免疫系统成熟与CMV病毒血症控制之间的关系。之前 研究表明，细胞毒性T淋巴细胞的两个群体，CD 8 T和gd T细胞，扩增， 在子宫内CMV感染时进行区分。我们假设T细胞在胎儿发育过程中产生 （包括CD 8和gd T细胞两者）本质上偏向于快速分化成终末效应细胞。 细胞我们进一步假设，这种效应器偏向的编程限制了婴儿CD 8 T细胞的能力， 产生持久控制慢性病毒所需的长寿记忆亚群， 感染这一假设得到了来自实验鼠模型的数据的支持，但尚未完全证实。 在自然病原体的背景下在人类婴儿中进行检查。虽然CD 8反应继续成熟， 出生后，gd T细胞在妊娠早期发育，并表现出许多类似先天的特性， 在子宫内作为重要的抗病毒效应器。值得注意的是，表达CMV-反应性gd TCR的gd T细胞， 预编程效应器功能在妊娠中期已经存在于胎儿胸腺中。这些胎儿生长激素 细胞在刺激时可被快速激活以产生IFNg和颗粒酶。因此，我们假设， 胎儿gd T细胞在子宫内介导抗CMV效应功能中起重要作用，而适应性ab T细胞在子宫内介导抗CMV效应功能中起重要作用。 细胞反应成熟。在前两个目标中，我们将比较先天性CMV患者中gd和CD 8 T细胞反应， 感染的新生儿到那些在生命的第二年获得原发性CMV感染的儿童， 以确定免疫成熟的关键途径。CD 8和gd T细胞将通过高- 参数细胞术，功能测定，以及配对的转录和TCRseq分析中的单个细胞。 为了根据发育窗口确定对CMV反应的差异， 感染发生了。在目标3中，我们将这些免疫学参数与临床后遗症和 解决婴儿期的病毒血症，以确定病毒遏制的免疫相关性。理解 婴儿对CMV免疫应答的变异性如何与临床和病毒学结局相关，以及年龄- 这种免疫反应的相关差异使得出生后病毒血症逐渐消退， 对早期生命中抗病毒T细胞功能的深刻见解。

Abstract: CMV infection in utero leads to prolonged viremia and often devastating clinical sequelae. In adults, it is established that the T cell response to CMV is required for containment of viremia. However, the immunologic determinants of viral control and clinical sequelae following congenital CMV infection are not known. In this project, we will study the immune response to CMV as a window into immune ontogeny and the age-related maturation of antiviral T cell function. We will leverage a large cohort of mother-infant pairs with samples banked longitudinally for immunologic studies. This cohort, which includes a large number of infants infected with CMV in utero and others infected during early childhood, affords a unique opportunity to examine the relationship between the age-related maturation of the immune system and control of CMV viremia. Prior studies have shown that two populations of cytotoxic T lymphocytes, CD8 T and gd T cells, expand and differentiate upon CMV infection in utero. We hypothesize that T cells generated during fetal development (including both CD8 and gd T cells) are intrinsically biased toward rapid differentiation into terminal effector cells. We further hypothesize that this effector-biased programming limits the ability of infant CD8 T cells to generate the long-lived memory sub-populations that are required for sustained control of a chronic viral infection. This hypothesis is supported by data from experimental murine models but has not been fully examined in human infants in the context of a natural pathogen. While the CD8 response continues to mature postnatally, gd T cells develop earlier in gestation and exhibit many innate-like qualities that could enable them to act as important antiviral effectors in utero. Remarkably, gd T cells that express CMV-reactive gd TCRs and pre-programmed effector functions are already present in the fetal thymus at mid-gestation. These fetal gd T cells can be rapidly activated to produce IFNg and granzymes upon stimulation. Hence, we hypothesize that fetal gd T cells play an important role in mediating anti-CMV effector functions in utero, while the adaptive ab T cell response matures. In the first two aims, we will compare gd and CD8 T cell responses in congenitally CMV- infected newborns to those of children who acquire primary CMV infection during the second year of life, in order to identify critical pathways of immune maturation. CD8 and gd T cells will be assessed by high- parameter cytometry, functional assays, and paired transcriptional and TCRseq profiling of individual cells in order to identify differences in the response to CMV based on the developmental window during which infection occurred. In Aim 3, we will relate these immunologic parameters to clinical sequelae and the resolution of viremia during infancy in order to identify immune correlates of viral containment. Understanding how variability in the infant immune response to CMV relates to clinical and virologic outcomes, and how age- related differences in this immune response enable the gradual resolution of viremia postnatally, could lend great insight into antiviral T cell function in early life.