Role of Daf in Systemic Autoimmunity

描述(申请人提供)：衰变加速因子(DAF，CD55)是补体调节蛋白家族的成员，保护细胞免受自体补体蛋白的攻击。最近，DAF被认为是获得性免疫反应的负调节因子。此外，在动物模型中，Daf1缺乏被证明会加重狼疮、重症肌无力和实验性自身免疫性脑脊髓炎(EAE)。我们发现，抵抗系统自身免疫诱导的DBA/2小鼠比易患狼疮的品系(NZB、NZW、MRL)有更高的DAF1表达。诱导B10.S小鼠汞诱导自身免疫(HgIA)可降低CD4T细胞表面Daf1mRNA水平和细胞表面表达。细胞分类发现来自HgIA小鼠的CD4 CD44hi T细胞具有最低水平的Daf1，这与升高的IL-4有关，在该模型中IL-4是活动性疾病的标志。虽然Daf1蛋白表达的主要调控似乎是在转录水平上，但我们发现NZB和DBA/2小鼠之间的差异表达不是来自Daf1基因和启动子的多态性。对Daf1启动子的进一步鉴定显示了正性和负性调节区，以及基础转录活性，这需要Sp1结合位点的功能协作。我们假设Daf1在获得性免疫反应中起关键作用，尤其是在CD4T细胞中，并且Daf1的低内源性表达易于发生自身免疫。本应用的具体目的如下：-1)我们将使用系统自身免疫的自发模型来定义Daf1表达减少与系统自身免疫发展之间的关系，2)我们将使用病毒和非病毒基因传递系统来研究Daf1水平的调节是否影响系统自身免疫的表达，3)我们将检查Daf1表达的调节因素，并验证Daf1表达的调节是由于调节Sp1转录活性的机制所致的假说。实验证实DAF1在调节淋巴细胞活性和发展全身自身免疫中的作用，将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。项目说明： 补体调节蛋白衰变加速因子(DAF)被认为在调节淋巴细胞活性和系统自身免疫的发展中起保护作用。该项目将使用基因疗法来确定增加自身免疫倾向小鼠中Daf1的表达水平是否能够防御自身免疫。

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.