Recent Thymic Emigrants of the CD4 T-cell Lineage

描述（由申请人提供）：表达a - t细胞受体的抗原性初始CD4对于产生对新抗原的免疫反应至关重要，并且在胸腺内作为成熟的CD4+CD8-胸腺细胞从头产生。这些细胞进入外周成为新生CD4 t细胞室的新近胸腺移植物（rte）。尽管监测CD4 rte具有重大的临床意义，特别是在CD4 t细胞淋巴细胞减少症中，但由于缺乏特异性表面标记物，对人类CD4 rte的直接评估受到限制。该项目将利用最近发现的一种新的人类CD4 RTE表面标记蛋白酪氨酸激酶7 （PTK7）来定义CD4 RTE频率、表型和功能。初步结果证实PTK7是CD4 RTE标志物，并表明与PTK7- naive CD4 T细胞相比，PTK7+ CD4 RTE的效应功能能力降低。目的1将通过对未受刺激和受刺激的PTK7+ CD4 RTE以及其他CD4 t谱系细胞进行深度mRNA测序来使用基因表达谱：1)确定PTK7+ CD4 RTE在个体发育过程中的残留胸腺细胞基因表达程度；2)鉴定与CD4 RTE免疫功能降低有关的基因产物，特别是Th1生成和/或将PTK7+ CD4 RTE细分为更近期或更近期的胸腺迁移。Aim 2将使用体内标记来验证PTK7+ CD4 rte是PTK7-初始CD4 T细胞的直接前体的假设，并将确定PTK7+ CD4 rte在维持HIV-1感染中初始CD4 T细胞数量和12-TCR库多样性中的作用。Aim 3将使用类似的方法来测试PTK7+ CD4 rte在同种异体造血干细胞移植后幼稚CD4 T细胞免疫重建中的重要性。目的4将定义儿童和成人完全胸腺切除术后PTK7+ CD4 rte丢失的动力学，以及这种丢失对初始CD4 t细胞数量和12- TCR库多样性的影响。总之，这些研究将大大增强我们对胸腺RTE产生在维持健康和疾病中外周初始CD4 t细胞区室中的作用的理解。

DESCRIPTION (provided by applicant): Antigenically naive CD4 expressing a¿-T cell receptors are critical for generating immune responses to neoantigens, and are produced de novo within the thymus as mature CD4+CD8- thymocytes. These enter the periphery to become recent thymic emigrants (RTEs) of the naive CD4 T-cell compartment. Although monitoring of CD4 RTEs is of great clinical interest, particularly in CD4 T-cell lymphopenia, direct evaluation of human CD4 RTEs has been limited by a lack of specific surface markers. This project will utilize a novel and recently identified surface marker for human CD4 RTEs, protein tyrosine kinase 7 (PTK7), to define CD4 RTE frequency, phenotype, and function. Preliminary results validate PTK7 as a CD4 RTE marker, and show that PTK7+ CD4 RTEs have a reduced capacity for effector function compared to PTK7- naive CD4 T cells. Aim 1 will use gene expression profiling by deep mRNA sequencing of unstimulated and stimulated PTK7+ CD4 RTEs and other CD4 T-lineage cells to: 1) define the extent of residual thymocyte gene expression in PTK7+ CD4 RTEs during ontogeny, and 2) identify gene products involved in reduced CD4 RTE immune function, particularly for Th1 generation and/or that subdivide PTK7+ CD4 RTEs into more versus less recent thymic emigrants. Aim 2 will use in vivo labeling to test the hypothesis that PTK7+ CD4 RTEs are the direct precursors of PTK7- naive CD4 T cells, and will determine the role of PTK7+ CD4 RTEs in maintaining naive CD4 T-cell numbers and 12-TCR repertoire diversity in HIV-1 infection. Aim 3 will use a similar approach to test the importance of PTK7+ CD4 RTEs in immune reconstitution of naive CD4 T cells after allogeneic hematopoietic stem cell transplantation. Aim 4 will define the kinetics of loss of PTK7+ CD4 RTEs in children and adults following complete thymectomy and the impact of this loss on naive CD4 T-cell numbers and 12- TCR repertoire diversity. Together, these studies will substantially enhance our understanding of the role of thymic RTE production in maintaining the peripheral naive CD4 T-cell compartment in health and disease.