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Foxp3DEx2 isoform expression leads to Treg dysfunction and SLE

Foxp3DEx2 同工型表达导致 Treg 功能障碍和 SLE

基本信息

批准号：
10363690
负责人：
Steven F Ziegler
金额：
$ 21.76万
依托单位：
BENAROYA RESEARCH INST AT VIRGINIA MASON
依托单位国家：
美国
项目类别：
财政年份：
2021
资助国家：
美国
起止时间：
2021-03-03 至 2023-08-31
项目状态：
已结题

项目摘要

Project Summary Regulatory T (Treg) cells play a central role in maintaining immune system homeostasis and modulating immune responses. Foxp3 is a master regulator of Treg development and function. FOXP3 mutations in patients with IPEX, which result in a deficiency in Tregs, result in lethal autoimmunity, similar to the disease observed in Foxp3 deficient mice. While highly conserved in both amino acid sequence and gene structure, one difference between humans and mice is that the human FOXP3 gene encodes two major alternatively spliced isoforms: a full length version that uses all 10 exons (FOXP3-FL, the only isoform in mice) and a shorter isoform lacking sequences shown to be important in regulating Th17 differentiation. Recent studies have shown that Tregs from patients with some autoimmune diseases express increased levels of the ∆E2 isoform compared to those from healthy donors. Consistent with this finding, we have found that Tregs from SLE patients have increased expression of the FOXP3∆Ex2 isoform. To study the role of the ∆E2 isoform in Treg function we generated a new mouse strain with Foxp3 exon 2 deletion. Interestingly, we found that Foxp3∆E2 mice develop hallmark features of SLE, including anti- DNA and anti-nuclear autoantibodies, increased number and size of spontaneous germinal centers and kidney deposition of antibody complexes, by 4-5 weeks of age. However, these mice do not develop full-blown disease and have a normal life span. Our central hypothesis is that the region encoded by exon 2 of Foxp3 gene is critical for normal Treg identity and function. To test this hypothesis we will take 2 approaches. First, we will determine the levels of FOXP3-FL and -∆Ex2-expressing Tregs in healthy human subjects and subjects with autoimmune disease. These studies will be complemented with studies using mice containing varying ratios of Tregs expressing each isoform. Second, we test the hypothesis that Tregs expressing FOXP3-∆Ex2 have a reduced ability to regulate effector T cell activation, using both human Treg clones and a mouse transfer colitis model. Together these studies will allow us to gain important information on the expression of FOXP3∆Ex2 and the function of Tregs expressing this isoform.

项目概要调节性 T (Treg) 细胞在维持免疫系统稳态和调节免疫反应。 Foxp3 是 Treg 发育和功能的主要调节因子。 FOXP3 IPEX 患者的突变会导致 Tregs 缺乏，从而导致致命的自身免疫，类似于在 Foxp3 缺陷小鼠中观察到的疾病。氨基酸序列和基因高度保守从结构上看，人类和小鼠之间的一个区别是人类 FOXP3 基因编码两个主要的选择性剪接异构体：使用全部 10 个外显子的全长版本（FOXP3-FL，小鼠中唯一的异构体）以及缺乏序列的较短同工型，该亚型对调节 Th17 分化很重要。最近的研究表明，某些自身免疫性疾病患者的 Tregs 表达水平升高 ΔE2 亚型与健康捐赠者的亚型相比。与这一发现一致的是，我们发现 Tregs SLE 患者的 FOXP3ΔEx2 亚型表达增加。为了研究 ΔE2 同种型在 Treg 功能中的作用，我们用 Foxp3 生成了一个新的小鼠品系外显子 2 缺失。有趣的是，我们发现 Foxp3ΔE2 小鼠出现 SLE 的标志性特征，包括抗 DNA 和抗核自身抗体、自发生发中心和肾脏的数量和大小增加 4-5周龄时抗体复合物沉积。然而，这些小鼠并没有发育成熟疾病并有正常的寿命。我们的中心假设是由外显子 2 编码的区域 Foxp3 基因对于正常的 Treg 身份和功能至关重要。为了检验这个假设，我们将采取 2 接近。首先，我们将确定健康人中表达 FOXP3-FL 和 -ΔEx2 的 Tregs 的水平受试者和患有自身免疫性疾病的受试者。这些研究将与使用小鼠的研究相补充含有不同比例的表达每种亚型的 Tregs。其次，我们检验 Tregs 的假设表达 FOXP3-ΔEx2 的调节效应 T 细胞激活的能力降低，使用人类 Treg 克隆和小鼠转移结肠炎模型。这些研究将使我们能够获得重要的信息 FOXP3ΔEx2 的表达和表达该亚型的 Tregs 的功能。