In Vivo Assessment of T Cell Kinetics in Individuals at Risk for Type 1 Diabetes

描述（由申请人提供）：在动物模型和患有T1 D的人中，T细胞与自身免疫性糖尿病的发病机制有关。CD 4+细胞总数无差异 T细胞已经在患有和没有T1 D的个体之间被鉴定。一些研究发现，在T1 D患者中，CD 4/CD 8 T细胞的相对数量和记忆区室的变化发生了变化;然而，没有一致的模式被描述。虽然Treg的缺乏明确地导致小鼠和人中自身免疫性糖尿病的早期发作，但大多数研究发现，患有和未患有疾病的人的外周血中存在的Treg数量没有差异。与CD 4 + T细胞数量的这些静态测量相反，有迹象表明，对抗原刺激、IL-2和IL-15的应答改变可能影响自身免疫性糖尿病中CD 4 + T细胞的分化、稳定性和增殖。我们和其他人已经发现了通过IL-2 R的信号传导受损的证据，并且T1 D受试者中FOXP 3表达的维持减少，这与小鼠中的研究一致，该研究表明Treg周转可能对免疫耐受的持久性具有重要意义。此外，我们已经表明，在T1 D中对IL-15的反应也是迟钝的。IL-2和IL-15都是影响记忆T细胞稳态的细胞因子。这些和其他因素可能会影响记忆池中的自我平衡增殖。评估 体外T细胞增殖和存活可能与体内测量无关。FoxP 3 + Treg在体外是无反应性的，但有迹象表明Treg是体内增殖性更强的细胞之一。此外，来自NOD小鼠和人类1型糖尿病受试者的Treg在体外扩增并发挥功能，但有迹象表明体内类似细胞具有受损的表型稳定性和功能。这些数据表明，为了充分了解1型糖尿病中的CD 4 + T细胞稳态，需要进行稳健的、纵向的体内分析。稳定同位素方法学的进展（用氧化氘（2 H2O）和氘代葡萄糖（2 H2-葡萄糖）标记）用于测量人体内细胞群的动力学。我们发现，与健康对照组相比，T1 D患者的CD 4+记忆T细胞具有更高的体内周转率（通过替换、增殖和消失率测量）。在这项提案中，我们的目标是评估糖尿病TrialNet和健康对照受试者确定的1型糖尿病风险个体的体内T细胞动力学。具体目的：目的1：确定在诊断1型糖尿病风险个体之前是否存在T细胞动力学改变。 目的2：确定T细胞动力学随时间的变化。

DESCRIPTION (provided by applicant): T cells are implicated in the pathogenesis of autoimmune diabetes in both animal models and in humans with T1D. No difference in the total number of CD4+ T cells has been identified between individuals with and without T1D. Some studies have found alterations in the relative number of CD4/CD8 T cells and alterations in the memory compartment in individuals with T1D; however, no consistent pattern has been described. While lack of Treg unambiguously results in the early onset of autoimmune diabetes in both mouse and man, most studies have found no difference in the number of Treg present in peripheral blood of humans with and without disease. In contrast to these static measurements of CD4+ T cell number, there are indications that altered responses to antigenic stimuli, IL-2, and IL-15 may impact differentiation, stability and proliferation of CD4+ T cells in autoimmune diabetes. We and others have found evidence of impaired signaling through the IL-2R, and diminished maintenance of FOXP3 expression in T1D subjects consistent with studies in mice which suggest Treg turnover may have important implications for the durability of immune tolerance. In addition we have shown that responses to IL-15 in T1D are also blunted. Both IL-2 and IL-15 are among the cytokines that influence memory T-cell homeostasis. These and other factors may influence the homeostatic proliferation in the memory pool. Assessments of T cell proliferation and survival in vitro may not correlate with in vivo measures. FoxP3+ Treg are anergic in vitro but there are indications that Treg are among the more proliferative cells in vivo. Further, Treg from both NOD mice and human type 1 diabetes subjects expand and function in vitro but there are indications that analogous cells in vivo have impaired phenotypic stability and function. These data suggest that robust, longitudinal, in vivo analyses are needed in order to fully understand CD4+ T cell homeostasis in type 1 diabetes. Advances in stable isotope methodologies (labeling with deuterium oxide (2H2O) and deuterated glucose (2H2-glucose) are used to measure the kinetics of cell populations in vivo in humans. We found that CD4+ memory T cells had greater in vivo turnover as measured by replacement, proliferation, and disappearance rates in T1D as compared with healthy control subjects. In this proposal, we aim to evaluate in vivo T cell kinetics in individuals at risk for type 1 diabetes identified by Diabetes TrialNet and healthy control subjects. Specific Aims: Aim 1: To determine whether altered T cell kinetics is present prior to diagnosis in individuals at risk for type 1 diabetes. Aim 2: To determine the changes in T cell kinetics over time.