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

项目总结 器官移植是终末性器官衰竭患者的标准治疗方法。虽然移植物存活率 多年来显著增加，许多患者失去了挽救生命的移植由于抗体- 中介性排斥。最近的研究表明，这些抗体的主要靶点是供体的人类白细胞抗原-DQ 分子。这一观察结果令人费解，因为该领域的领先公约认为人类白细胞抗原-DR是另一种 人类白细胞抗原II类分子，作为主要的“移植抗原”。现在很明显，频率和 抗HLADQ抗体的致病性高于HLADR(和HLADP，第三类HLAII) 分子)。目前，还没有对这些观察到的机械解释。我们的中心假设是 在进化压力下，人类白细胞抗原DR、人类白细胞抗原DQ和人类白细胞抗原DP被特化，以控制略有不同的 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，它们提供 类似的功能，但针对不同的波长，以最大限度地提高对颜色的敏感度。 重要的是，绝大多数的机制研究都集中在人类白细胞抗原-DR上，并且假设人类白细胞抗原-DQ 和人类白细胞抗原-DP使用相同的免疫途径。我们的长期目标是了解导致 同种异体移植中人类白细胞抗原-DQ错配的免疫原性和致病性增加(与 人类白细胞抗原-DR和人类白细胞抗原-DP)。其目的是从不允许的HLA-DQ错配中破译允许的，以及 进一步阐明人类白细胞抗原-DQ同种异体识别优先刺激的免疫激活途径。 具体地说，在目标1中，我们将定义导致发展的人类白细胞抗原-DQ错配的免疫原性 移植受者中供者特异性的人类白细胞抗原-DQ抗体。我们将使用计算和实验 包括吸附/洗脱和定点突变研究在内的预测定性的方法 人类白细胞抗原DQ表位的特征。在目标2中，我们将比较结扎所触发的免疫激活途径 不同的人类白细胞抗原II类分子。我们将评估三种不同的免疫反应机制： 由抗体本身的性质介导；那些被转导到连接的HLAII类下游的抗体 分子；以及那些通过识别不同II类分子的T细胞受体而激发的分子。我们将使用 尖端蛋白质组技术以及CRISPR-Cas9编辑的细胞只表达一个人类白细胞抗原II类等位基因 作为询问这些特定途径的创新工具。总而言之，该项目将支持两个重要的 实体器官移植的进展：器官分配和个人化医学 免疫抑制管理，以及为药物开发确定新的免疫靶点。 供移植的器官短缺，与需要移植器官相关的医疗和财政影响 治疗同种异体移植排斥反应以及免疫抑制和移植物功能障碍/缺失对患者生活质量的影响 所有这些都突显了改善器官移植结果的未得到满足的需求。拟议的工作与NIAID是一致的 开展应用研究以更好地了解、治疗并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.