Structure-function of HLA-DR, peptides, and T cells in autoimmune arthritis

描述(由申请人提供)： 这些研究的总体目标是促进我们对致病T细胞反应在自身免疫中的作用的理解，并确定刺激致病T细胞反应的人类白细胞抗原-DR的结构参数：多肽。为此，我们对RA相关等位基因HLA-DR1和DR4在自身抗原肽呈递过程中的结构和功能进行了一些有意义的观察。利用我们为研究模型自身抗原II型胶原(CII)而建立的人源化小鼠模型，我们鉴定了由DR1和DR4类II分子呈现的CII免疫优势决定簇，定义了在这些DR分子与该多肽结合和T细胞受体识别该复合体的过程中发生的分子相互作用，解决了人类白细胞抗原-DR1与免疫优势CII多肽的络合物的晶体结构，并发展了一种在体外识别CII特异性自身免疫T细胞的方法，用于这些细胞的高度特异性和功能研究。基于这些数据，本建议的重点是研究DR分子与CII多肽的结合亲和力与这种结合亲和力对CII特异性自身免疫T细胞的刺激和功能的影响之间的结构-功能关系。我们在这项提议中检验的中心假设是，自体多肽与MHC II类分子的低亲和力相互作用导致II类多肽复合体的构象发生显著变化，这种变化的结构在自身免疫T细胞的刺激和功能中发挥主要作用。这些研究将对自身免疫产生重大影响，因为它们解决了一个开创性的问题--MHC分子如何调节自身免疫的易感性？此外，这些研究将确定自身免疫T细胞的表型和它们在介导疾病中的作用机制，并将确定MHC：肽低亲和力自身免疫反应与高亲和力外源抗原性反应的不同之处。这些研究的长期前景是，它们将为我们提供新的结构/功能概念，可以有针对性地开发高度特异的自身免疫疗法。 公共卫生相关性： 我们知道，在40多种自身免疫性疾病中，易感性与特定的HLA-DR II类基因的表达有关。在这些研究中，我们将使用人源化的人类白细胞抗原-DR1自身免疫性关节炎小鼠模型来研究自身免疫T细胞反应的致病机制。这种自身免疫性疾病模型是类风湿性关节炎(RA)研究最广泛的模型。通过这项提议中的实验，我们将对自身免疫T细胞反应的进化以及与自身抗原结合的HLADR分子结构如何决定这些致病T细胞的功能有新的认识。我们的长期目标是这些研究导致开发新的高度特异的方法来干预自身免疫反应，消除无电流特定治疗的不良副作用，并提供调节自身免疫反应的直接手段。

DESCRIPTION (provided by applicant): The overall goal of these studies is to advance our understanding of the function of a pathogenic T cell response in autoimmunity and to define the structural parameters of the HLA-DR: peptidelig and that stimulates the pathogenic T cell response. Toward this goal, we have made several significant observations regarding the structure and function of the RA associated alleles HLA-DR1 and DR4 in the presentation of auto antigenic peptides. Using a humanized mouse model we have developed for the study of the model auto antigen type IIcollagen (CII), we have identified the CII immunodominant determinants presented by the DR1and DR4 class II molecules, defined the molecular interactions that occur during both the binding of this peptide by these DR molecules and the recognition of this complex by the T cell receptor, solved the crystal structure of HLA-DR1 complexed with the immunodominant CIIpeptide, and developed a means of identifying CII-specific autoimmune T cells ex vivo for highly specific, functional studies of these cells. Based on these data, the focus of this proposal is to investigate the structure-function relationship between the binding affinity of theCII peptide by the DR molecules and the effect of this binding affinity on the stimulation and function of the CII-specific autoimmune T cells. The central hypothesis that we are testing in this proposal is that the low affinity interaction of self peptides with MHC class II molecules induces significant changes in the conformation of the class II: peptide complex, and that this altered structure plays a major role in the stimulation and function of autoimmune T cells. The impact of these studies will be significant to autoimmunity in general in that they address a seminal question - how do MHC molecules mediate susceptibility to autoimmunity? In addition, these studies will identify the phenotype of the autoimmune T cells and the mechanisms by which they function in mediating disease, and will determine how an MHC: peptide low affinity autoimmune response differs from a high affinity foreign anti genresponse. The long term prospect of these studies is that they will provide us with new structural/functional concepts that can be targeted for the development of highly specific immunotherapies for autoimmunity. PUBLIC HEALTH RELEVANCE: There are more than 40 autoimmune diseases in which we know the susceptibility isassociated with the expression of specific HLA-DR class II genes. In these studies we will usethe humanized HLA-DR1 autoimmune arthritis mouse model to study the a pathogenicautoimmune T cell response. This autoimmune disease model is the most widely studiedmodel of rheumatoid arthritis (RA). Through the experiments in this proposal we will gain newinsight into the evolution of an autoimmune T cell response and how the structure of an HLADRmolecule complexed with an autoantigen dictates the function of these pathogenic T cells.It is our long term goal that these studies lead to the development of new highly specific meansof intervening in autoimmune responses, to eliminate the undesirable side effects of currentless specific treatments, and provide direct means of regulating autoimmune responses.VA Public