The immunogenicity and pathogenicity of HLA-DQ in solid organ transplantation

项目摘要 器官移植是终末器官衰竭患者的标准治疗。尽管移植物存活率 近年来，这种疾病的发病率显著增加，许多患者因抗体而失去了挽救生命的移植手术， 介导的排斥最近的研究表明，这些抗体的主要靶点是供体HLA-DQ 分子。这一观察结果令人困惑，因为该领域的主要公约认为HLA-DR，另一个 HLA-II类分子，作为主要的“移植抗原”。现在很明显，频率和 抗HLA-DQ抗体的致病性高于HLA-DR（和HLA-DP，第三种II类HLA）， 分子）。目前还没有对这些现象的机械解释。我们的核心假设是， HLA-DR、HLA-DQ和HLA-DP通过进化压力被专门化，以控制不同的细胞。 免疫激活的途径。这可以比作3种类型的视锥感光细胞类型， 类似的功能性，但是用于不同的波长以最大化对颜色的灵敏度。 重要的是，绝大多数机制研究集中在HLA-DR上，并且假设HLA-DQ 和HLA-DP使用相同的免疫途径。我们的长期目标是了解导致 HLA-DQ错配在同种异体移植中的免疫原性和致病性增加（与对照组相比）， HLA-DR和HLA-DP）。目的是从不允许的HLA-DQ错配中破译允许的，并且 进一步阐明优先受HLA-DQ同种异体识别刺激的免疫活化途径。 具体而言，在目标1中，我们将定义导致发展的HLA-DQ错配的免疫原性。 供者特异性HLA-DQ抗体在移植受者中的作用。我们将使用计算和实验 包括吸附/洗脱和定点诱变研究在内的方法， HLA-DQ表位的特征。在目标2中，我们将比较连接触发的免疫激活途径 不同的HLA II类分子。我们将评估免疫反应的3种不同机制： 由抗体本身的性质介导;那些向内转导的，连接的HLA II类下游 分子;以及通过识别不同II类分子的T细胞受体引发的那些。我们将使用 尖端蛋白质组学技术以及仅表达一个HLA II类等位基因的CRISPR-Cas9编辑细胞 作为一种创新的工具来探究这些特定的途径。总的来说，该项目将支持两个重要的 实体器官移植的进展：关于器官分配和 免疫抑制管理和鉴定用于药物开发的新免疫靶点。 移植器官的短缺，与需要移植相关的医疗和财政后果， 治疗同种异体移植物排斥反应，以及免疫抑制和移植物功能障碍/丧失对患者生活质量的影响 所有这些都突出了对改善器官移植结果的未满足的需求。拟议的工作符合NIAID 开展应用研究以更好地了解、治疗和最终预防移植排斥反应的使命。

PROJECT SUMMARY Organ transplantation is a standard-of-care treatment for patients with end-organ failure. Although graft survival has increased significantly over the years, many patients lose their life-saving transplant due to antibody- mediated rejection. Recent work demonstrated that the main target of these antibodies are donor HLA-DQ molecules. This observation is puzzling since the leading convention in the field considered HLA-DR, another type of HLA-class II molecules, as the leading “transplantation antigens”. It is now clear that the frequency and pathogenicity of antibodies against HLA-DQ is higher than HLA-DR (and HLA-DP, the third class II HLA molecules). Currently, there is no mechanistic explanation to these observations. Our central hypothesis is that HLA-DR, HLA-DQ, and HLA-DP were specialized, through evolutionary pressure, to control somewhat different pathways of immune activation. This can be likened to the 3 types of cone photoreceptor cell types that provide similar functionality but for different wavelengths to maximize sensitivity to color. Importantly, the vast majority of mechanistic studies focused on HLA-DR, and the assumption is that HLA-DQ and HLA-DP use identical immune pathways. Our long-term goal is to understand the mechanism leading to the increased immunogenicity and pathogenicity of HLA-DQ mismatches in allo-transplantation (compared with HLA-DR and HLA-DP). The objective is to decipher permissible from non-permissible HLA-DQ mismatches, and further to elucidate immune activation pathways that are preferentially stimulated by HLA-DQ allo-recognition. Specifically, in Aim 1, we will define the immunogenicity of HLA-DQ mismatches that lead to the development of donor-specific HLA-DQ antibodies in transplant recipients. We will use computational and experimental approaches including adsorption/elution and site directed mutagenesis studies to prognosticate qualitative characteristics of HLA-DQ epitopes. In Aim 2, we will compare immune activation pathways triggered by ligation of different HLA class II molecules. We will evaluate the 3 different mechanisms of the immune response: those mediated by qualities of the antibody itself; those transduced inwards, downstream of the ligated HLA class II molecules; and those elicited via the T cell receptor recognizing the different class II molecules. We will use cutting edge proteomic technology as well as CRISPR-Cas9 edited cells expressing only one HLA class II allele as innovative tools to interrogate these specific pathways. Taken together, this project will support two significant advancements in solid organ transplantation: personalized medicine with respect to organ allocation and immunosuppressive management, and identification of novel immune targets for drug development. The shortage of organs for transplantation, the medical and financial ramifications associated with the need to treat allograft rejection, and the impact of immunosuppression and graft dysfunction/loss on patient quality of life all highlight an unmet need for improving organ transplant outcomes. The proposed work is in line with the NIAID mission of conducting applied research to better understand, treat, and ultimately prevent transplant rejection.