Donor-specific B cells in Transplantation

摘要 肾移植引发强大的B细胞反应，产生针对移植的抗体 捐赠者。B细胞对同种异体人类白细胞抗原的反应(群体反应性抗体，PRA)和对移植供者(供者- 特异性抗体(DSA)与排斥反应和移植物丢失的风险相关，因此可作为诊断 你好--豁免权。产生DSA的B细胞反应会引发最令人烦恼的排斥反应类型(抗体- 介导性排斥反应)和慢性排斥反应，因此对治疗方法的发展很感兴趣 它们专门针对B细胞。然而，一些B细胞反应可能与移植相关，甚至可能促进移植 生存(免疫调节、适应、手术耐受性)。尽管已经有了广泛的 对血液DSA的特异性和功能的研究几乎对血液DSA的性质一无所知 供者特异性B细胞。我们提出的研究将首次确定 肾移植受者的供者特异性B细胞反应以确定哪些特性相关 并可能有助于稳定的移植物功能，而不是排斥反应。作为第一个目标， 将通过测定供体的重链和轻链Ig序列来研究供体特异性的B细胞反应。 单细胞测序和核糖核酸序列分析B细胞表型。我们将决定关键 免疫球蛋白的特性，如克隆多样性、体细胞超突变程度或独立于免疫球蛋白的特性，如 功能稳定或排斥的受者产生细胞因子。作为第二个目标，供体特异性免疫球蛋白 NGS获得的序列将在一年(最多两年)的时间内进行前瞻性研究。我们会 确定克隆型是否会像T细胞预期的那样，在排斥反应的预期中扩大和多样化 依赖反应；以及排斥治疗后供体特异性序列的变化。我们还将 确定在移植物稳定的受者中，供者特异性B细胞是否编码具有不同特性的免疫球蛋白。作为第三人 目标，我们将进行关键属性的第一次调查(例如最大结合、亲和力、直接 供体细胞的激活和抗原特异性，在可能的情况下，使用移植组织证实)重组 在供体细胞上进行单克隆性DSA以确定这些特性是否可以解释 致病性。这项研究可能会揭示评估风险的新方法和生物学的新目标 干预。这项研究还可能启发合理的方法来改变移植过程中的B细胞反应 以个性化的方式接受治疗，目的是促进保护性反应和对抗 致病的。

Abstract Kidney transplantation elicits powerful B cell responses that generate antibodies specific for the transplant donor. B cell responses to allogeneic HLA (panel reactive antibodies, PRA) and to the transplant donor (donor- specific antibodies, DSA) correlate with risk of rejection and graft loss and thus serve as diagnostic indices of allo-immunity. B cell responses that generate DSA initiate the most vexing types of rejection (antibody- mediated rejection, ABMR) and chronic ABMR and hence much interest exists in development of therapeutics that specifically target B cells. Some B cell responses however may correlate with or even promote graft survival (immune regulation, accommodation, operational tolerance). Although there has been extensive investigation of the specificity and function of the blood DSA hardly anything is known about the properties of donor-specific B cells. The research we propose will identify for the first time key characteristics of donor-specific B cell responses in kidney transplant recipients to determine what properties associate with and potentially contribute to stable graft function, as opposed to rejection. As a first objective, donor-specific B cell responses will be studied by determining Heavy and Light chain Ig sequences of donor- specific B cells by single cell sequencing and their phenotypic signature by RNA-seq . We will determine key properties of Ig, such as clonal diversity, extent of somatic hypermutation or Ig independent properties such as production of cytokines in recipients with stable function or rejection. As a second objective, donor-specific Ig sequences obtained by NGS will be studied prospectively over periods > a year (up to two years). We will determine whether clonotypes expand and diversify in anticipation of rejection as would be expected of T cell dependent responses; and how donor-specific sequences change following rejection treatment. We will also determine if in recipients with stable grafts, donor-specific B cells encode Igs with distinct properties. As a third objective, we will conduct the first investigation of key properties (e.g. maximum binding, avidity, direct activation of donor cells and antigen specificity, where possible, confirmed using graft tissues) of recombinant monoclonal DSA on donor cells to determine whether these properties could explain differences in pathogenicity. The research might reveal novel approaches to assessing risk and new targets for biological intervention. The research might also inspire rational approaches to modifying B cell responses in transplant recipients in a personalized manner with the goal of promoting protective responses and antagonizing pathogenic ones.