Role of Daf in Systemic Autoimmunity

描述（由申请人提供）：衰变加速因子（CD 55）是补体调节蛋白家族的一员，可保护细胞免受自体补体蛋白的攻击。近年来，研究人员发现，免疫球蛋白是适应性免疫反应的负调节因子。此外，在动物模型中，Daf 1缺陷显示出加重狼疮、重症肌无力和实验性自身免疫性脑脊髓炎（EAE）。我们发现，DBA/2小鼠，这是抵抗诱导系统性自身免疫，具有较高的表达Daf 1相比，狼疮易感株（NZB，NZW，MRL）。在B10.S小鼠中诱导汞诱导的自身免疫（HgIA）降低Daf 1 mRNA水平和CD 4 T细胞上的细胞表面表达。细胞分选鉴定HgIA小鼠的CD 4 CD 44 hi T细胞具有最低水平的Daf 1，这与升高的IL- 4相关; IL- 4是该模型中活动性疾病的标志物。虽然Daf 1蛋白表达的主要控制似乎是在转录水平上，我们发现NZB和DBA/2小鼠之间的差异表达不是来自Daf 1基因和启动子多态性。Daf 1启动子的进一步表征揭示了正调控区和负调控区，以及需要Sp1结合位点的功能合作的基础转录活性。我们假设Daf 1在获得性免疫应答中起关键作用，特别是CD 4 T细胞，并且Daf 1的低内源性表达易患自身免疫。本申请的具体目的将解决以下问题：1）我们将使用系统性自身免疫的自发模型来定义Daf 1表达降低与系统性自身免疫的发展之间的关系，2）我们将使用病毒和非病毒基因递送系统来询问Daf 1水平的操纵是否影响系统性自身免疫的表达，3）我们将检查是什么调节Daf 1的表达，并测试在自身免疫中Daf 1表达的调节是由于调节Sp1的转录活性的机制的假设。实验证实Daf 1在调节淋巴细胞活性和全身性自身免疫发展中的作用，将大大有助于我们理解自身免疫性疾病的过程，并有助于开发新的治疗干预措施。项目叙述： 补体调节蛋白衰变加速因子（decay accelerating factor，CRFF）被认为在调节淋巴细胞活性和系统性自身免疫的发展中起保护作用。该项目将使用基因治疗来确定增加自身免疫易感小鼠中Daf 1的表达水平是否可以防御自身免疫。

DESCRIPTION (provided by applicant): Decay accelerating factor (DAF, CD55) is a member of the complement-regulatory protein family that protects cells from attack by autologous complement proteins. Recently DAF was identified as a negative regulator of adaptive immune responses. Furthermore, Daf1 deficiency was shown to exacerbate lupus, myasthenia gravis and experimental autoimmune encephalomyelitis (EAE) in animal models. We found that DBA/2 mice, which are resistant to induction of systemic autoimmunity, have higher expression of Daf1 compared with lupus-prone strains (NZB, NZW, MRL). Induction of mercury-induced autoimmunity (HgIA) in B10.S mice decreases Daf1 mRNA levels and cell surface expression on CD4 T cells. Cell sorting identified CD4 CD44hi T cells from HgIA mice as having the lowest level of Daf1, and this was associated with elevated IL- 4; a marker of active disease in this model. Although primary control of Daf1 protein expression appears to be at the level of transcription, we found that the differential expression between NZB and DBA/2 mice was not from Daf1 gene and promoter polymorphisms. Further characterization of the Daf1 promoter revealed positive and negative regulatory regions, and basal transcriptional activity that requires functional cooperation of Sp1-binding sites. We hypothesize that Daf1 plays a critical role in the adaptive immune response, particularly of CD4 T cells, and that low endogenous expression of Daf1 predisposes to autoimmunity. The specific aims of this application will address the following:- 1) We will use spontaneous models of systemic autoimmunity to define the relationship between reduced Daf1 expression and the development of systemic autoimmunity, 2) We will use viral and non-viral gene delivery systems to ask if manipulation of the level of Daf1 influences expression of systemic autoimmunity, 3) We will examine what regulates expression of Daf1, and test the hypothesis that regulation of Daf1 expression in autoimmunity is due to mechanisms regulating the transcriptional activity of Sp1. Experimental confirmation of a role for Daf1 in regulating lymphoid cell activity, and development of systemic autoimmunity, will contribute significantly to our understanding of the autoimmune disease process and aid in the development of novel therapeutic interventions. Project Narrative: The complement regulatory protein decay accelerating factor (DAF) is hypothesized to play a protective role in regulating lymphoid cell activity and development of systemic autoimmunity. This project will use gene therapy to determine if increasing the level of expression of Daf1 in autoimmune prone mice offers a defense against autoimmunity.