Role of HLA Class II Genes in Demyelination

描述（由申请人提供）：多发性硬化症（MS）是一种炎症性脱髓鞘自身免疫性疾病，具有遗传和环境倾向。在所有与MS易感性相关的遗传因素中，HLA-II类单倍型如DR 2/DQ 6、DR 3/DQ 2、DR 4/DQ 8显示出最强的关联。虽然HLA-DR等位基因在MS中的直接作用已被证实，但由于强烈的连锁不平衡，HLA-DQ等位基因在疾病发病机制中的作用一直难以理解。人口研究表明，DQ等位基因可能发挥调节作用，MS的进展。为了更好地了解HLA-DR和DQ基因的机制，有助于MS的易感性和抗性，我们产生了单和双转基因小鼠表达HLA II类基因，缺乏内源性小鼠II类基因。先前，我们已经证明HLA-DR 3转基因小鼠对PLP 91 -110诱导的EAE易感，而DQ 6（DQB 1 *0601）和DQ 8（DQB 1 *0302）转基因小鼠具有抗性。令人惊讶的是，DQ 6/DR 3双转基因小鼠具有抗性，而DQ 8/DR 3小鼠显示出更高的疾病发病率和严重程度。DQ 6在DQ 6/DR 3小鼠中的保护作用由抗炎IFN 3介导，而DQ 8分子的疾病加重作用由IL 17介导。基于这些观察结果，我们假设，HLA-DR和DQ基因之间的上位相互作用在MS的易感性中起着重要的作用。该建议的目的是提高对HLA-DQ和-DR分子之间的上位相互作用决定疾病的易感性与抵抗力的机制的理解。我们提出了两个目标，以了解HLA-DQ分子调节HLA-DR/DQ双转基因小鼠的疾病结果的机制。在第一个目标中，我们将通过分析以下来检查HLA-DQ 8分子如何增加DQ 8/DR 3双转基因小鼠中的疾病发病率和严重程度：i）HLA多态性和肽-MHC亲和力/亲合力在从DQ 8限制性CD 4 T细胞产生促炎性IL 17中的作用; ii）IL 17引起DR 3DQ 8小鼠中致脑炎性增加的机制;和iii）由DQ 8限制性CD 4 T细胞产生的GM-CSF在DR 3DQ 8双转基因小鼠中EAE恶化中的作用。在第二个目标中，我们将研究HLA-DQ 6限制性免疫应答如何导致产生高IFN 3产生的调节性CD 4 + T细胞，特别是MHC-肽亲和力/功能亲合力的作用。接下来，我们将分析DQ 6限制性CD 4 + T细胞抑制HLA-DR 3/DQ 6双转基因小鼠中EAE的机制。我们还将产生表达疾病易感性HLA-DR 3、疾病保护性-DQ 6和疾病增强性-DQ 8基因的三重转基因小鼠以模拟人类杂合条件。在这项建议中概述的综合研究应该产生一个深入了解的机制，HLA II类分子的形状T细胞库和调节促炎和抗炎细胞因子的配置文件。这将促进新型治疗剂的转化研究开发，以治疗炎症性疾病，如MS。

DESCRIPTION (provided by applicant): Multiple sclerosis (MS), an inflammatory and demyelinating autoimmune disease has both a genetic and an environmental predisposition. Among all the genetic factors associated with MS susceptibility, HLA-class II haplotypes such as DR2/DQ6, DR3/DQ2, DR4/DQ8, show the strongest association. Although a direct role of HLA-DR alleles in MS have been confirmed, it has been difficult to understand the contribution of HLA-DQ alleles in disease pathogenesis, due to strong linkage disequilibrium. Population studies have indicated that DQ alleles may play a modulatory role in progression of MS. To better understand the mechanism by which HLA-DR and -DQ genes contribute to susceptibility and resistance to MS, we generated single and double transgenic mice expressing HLA class II genes and lacking endogenous mouse class II genes. Previously, we have shown that HLA-DR3 transgenic mice were susceptible to PLP91-110 induced EAE, while DQ6 (DQB1*0601) and DQ8 (DQB1*0302) transgenic mice were resistant. Surprisingly DQ6/DR3 double transgenic mice were resistant while DQ8/DR3 mice showed higher disease incidence and severity. Protective effect of DQ6 in DQ6/DR3 mice was mediated by anti-inflammatory IFN3, while disease exacerbating effect of DQ8 molecule was mediated by IL17. Based on these observations, we hypothesize that epistatic interaction between HLA-DR and -DQ genes play an important role in predisposition to MS. This proposal is aimed to enhance understanding of the mechanism by which epistatic interactions between HLA-DQ and -DR molecules determine the susceptibility vs. resistance to disease. We are proposing two aims to understand the mechanism by which HLA-DQ molecule modulate the disease outcome in HLA-DR/DQ double transgenic mice. In the first aim, we will examine how HLA-DQ8 molecule increases disease incidence and severity in DQ8/DR3 double transgenic mice by analyzing- i) role of HLA polymorphism and peptide-MHC affinity/avidity in generation of pro-inflammatory IL17 production from DQ8 restricted CD4 T cells; ii) mechanism by which IL17 cause increased encephalitogenicity in DR3DQ8 mice; and iii) role of GM-CSF produced by DQ8 restricted CD4 T cells in exacerbation of EAE in DR3DQ8 double transgenic mice. In the second aim, we will investigate how HLA-DQ6 restricted immune response leads to generation of high IFN3 producing regulatory CD4+ T cells, especially the role of MHC-peptide affinity/functional avidity. Next we will analyze mechanisms by which DQ6 restricted CD4+ T cells suppress EAE in HLA-DR3/DQ6 double transgenic mice. We will also generate a triple transgenic mice expressing disease susceptible HLA-DR3, disease protective -DQ6, and disease enhancing -DQ8 gene to simulate human heterozygous condition. The comprehensive studies outlined in this proposal should yield an insight into mechanism by which HLA class II molecules shape the T cell repertoire and regulate the pro-inflammatory and anti-inflammatory cytokine profile. This will facilitate the translational research development of novel therapeutic to treat inflammatory disease such as MS.