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

描述(申请人提供)：在两种动物模型和患有T1D的人类中，T细胞都与自身免疫性糖尿病的发病机制有关。CD4+细胞总数无差异 已经在患有和不患有T1D的个体之间发现了T细胞。一些研究发现，在患有T1D的个体中，CD4/CD8 T细胞的相对数量发生了变化，记忆室也发生了变化；然而，还没有描述一致的模式。虽然缺乏Treg无疑会导致小鼠和人类早期发生自身免疫性糖尿病，但大多数研究发现，患有疾病和没有疾病的人外周血中Treg的数量没有差异。与这些对CD4+T细胞数量的静态测量相反，有迹象表明，自身免疫性糖尿病患者对抗原刺激、IL-2和IL-15的反应改变可能会影响CD4+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-2R的信号转导受损的证据，并且在T1D受试者中FOXP3表达的维持减少与在小鼠中的研究一致，该研究表明Treg的转换可能对免疫耐受的持久性有重要的影响。此外，我们已经证明，T1D对IL-15的反应也是迟钝的。IL-2和IL-15都是影响记忆T细胞动态平衡的细胞因子。这些因素和其他因素可能会影响内存池中的动态平衡增殖。对以下方面的评估 T细胞在体外的增殖和存活可能与体内的措施无关。Foxp3+Treg在体外是无能的，但有迹象表明Treg是体内增殖较多的细胞之一。此外，来自NOD小鼠和人类1型糖尿病受试者的Treg在体外扩张和功能，但有迹象表明，体内类似的细胞损害了表型稳定性和功能。这些数据表明，为了充分了解1型糖尿病患者的CD4+T细胞稳态，需要进行可靠的、纵向的体内分析。稳定同位素方法的进展(用重水(2H2O)和重氢葡萄糖(2H2-葡萄糖)标记)被用来测量人体内细胞群体的动力学。我们发现，与健康对照组相比，通过T1D的替换、增殖和消失率来衡量，CD4+记忆T细胞在体内的周转率更高。在这项建议中，我们旨在评估糖尿病试验网络和健康对照受试者中1型糖尿病高危个体的体内T细胞动力学。具体目的：目的1：确定1型糖尿病高危人群在确诊前是否存在T细胞动力学改变。 目的2：测定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.