Role of S1P1 in the function of Regulatory T cells in Autoimmune Encephalomyeliti

描述(申请人提供)：最近，S1P和S1P受体被专门用于治疗免疫介导性疾病，特别是免疫抑制剂FTY720(Fingolimod Gilenya)，这是一种S1P类似物，最近成为第一个治疗复发性多发性硬化症的口服疗法。FTY720有效降低复发率 比干扰素β疗法更好；然而，使用FTY720治疗的患者中的一部分会出现非常严重的复发，甚至肿瘤病变。这一发现表明，S1P1介导的信号可能参与了一些未知的免疫调节，除了它在T和B细胞运输中的作用。尽管FTY720在体内被磷酸化为FTY720-P后是作为激动剂还是功能拮抗剂仍存在争议，但了解FTY720如何影响T调节细胞(Tregs)的功能对于限制该药物长期治疗的不良反应至关重要。为了解决S1P对Tregs的特定作用，我们培育了只在Tregs中缺乏S1P1的小鼠。我们在S1P1 Treg缺陷小鼠的胸腺中发现了比WT小鼠多10倍的Tregs，然而，我们发现S1P1并不是Tregs从淋巴结或组织转运出去所必需的。缺乏S1P1的Treg细胞在体外仍能抑制IL-10、转化生长因子β、CD25和CTL4的表达，但这些Treg细胞在体内失去了控制免疫反应的能力。事实上，S1P1 Treg缺陷小鼠发展迅速而严重的系统性自身免疫，揭示了S1P对Treg功能的关键作用。因此，从我们的初步情况来看 我们假设S1P1介导的信号是：1)对Tregs从胸腺排出至关重要，2)对Tregs在淋巴器官内的精细定位至关重要，3)对Tregs在中枢神经系统等组织中的抑制功能至关重要。虽然S1P1介导的信号是T细胞输出和运输所必需的，但S1P1可能以不同的方式控制Treg的功能。至 针对这些假说，我们建议实现以下特定目标：目的1.S1P1在胸腺Treg细胞生成中的作用目的2.研究S1P1表达受损是否影响Treg在次级淋巴组织中的定位目的3.确定选择性S1P1对Treg细胞在中枢神经系统的迁移和EAE发生发展的需求。这一新的小鼠品系和新发现将帮助我们了解S1P和Fingolimod在多发性硬化症过程中如何影响Treg的功能。

DESCRIPTION (provided by applicant): Recently, S1P and S1P receptors have been specifically targeted as treatments for immune-mediated diseases, particularly the immunosuppressant FTY720 (Fingolimod Gilenya), an S1P analogue that has recently become the first oral therapy for relapsing Multiple Sclerosis. FTY720 effectively decreases relapse rates better than interferon β therapy; however, a subset of patients treated with FTY720 develop very severe relapses and even tumorfactive lesions. This finding suggests that S1P1-mediated signaling may be involved in some unknown immune regulation, in addition to its role in T and B cell trafficking. Although it remains controversial whether FTY720, after being phosphorylated to FTY720-P in vivo, acts as an agonist or a functional antagonist, understanding how FTY720 affects the function of T regulatory cells (Tregs) is crucial for limiting the adverse effects of lng term therapy with this drug. In order to address the specific role of S1P on Tregs, we have generated mice that lack S1P1 only in Tregs. We have found 10 times more Tregs in the thymus of S1P1 Treg-deficient mice compared to WT mice In the periphery however, we have found that S1P1 is not required for the egress of Tregs from lymph nodes or their tissue trafficking. Tregs that lack S1P1 could still suppress in vitro and expressed normal levels of IL-10, TGF beta, CD25 and CTL4; however, these Tregs lost their ability to control immune responses in vivo. Indeed, S1P1 Treg-deficient mice developed rapid and severe systemic autoimmunity, revealing a critical role of S1P for the function of Treg. Thus, from our preliminary data we hypothesize that S1P1-mediated signaling is: 1) crucial for the egress of Tregs from the thymus, 2) crucial for the fine positioning of Tregs within lymphoid organs and 3) crucial for the suppression function of Tregs in tissues such as the CNS. Whereas S1P1-mediated signaling is required for T cell egress and trafficking, S1P1 may control the functions of Tregs differently. To address these hypotheses, we propose to carry out the following specific aims: Aim 1. Role of S1P1 in the generation of Tregs in the Thymus Aim 2. Investigate whether compromised S1P1 expression affects Treg positioning in secondary lymphoid tissues Aim 3. Determine the requirement of selective S1P1 for the migration of Treg cells in the CNS and the development of EAE. This novel mouse strain and new findings will help us understand how S1P and Fingolimod affect the function of Tregs during the course of Multiple Sclerosis.