Immune Deregulation and Chronic Humoral Rejection of Kidney Allografts in Humans

描述（由申请人提供）：美国每年进行的肾脏移植数量正在增加。虽然在过去的十年中，早期移植物的存活率有所提高，但长期存活率在同一时期并没有显著改变，仍然令人不满意。越来越多的证据表明，慢性体液性排斥反应（CHR）是晚期肾移植损失的主要原因。从表面上看，CHR对常规免疫抑制疗法反应不佳。更好地了解这种并发症的病理生理学将导致新的治疗方法的发展，并降低排异率。我们提出的研究的长期目标是了解导致CHR的免疫机制。CHR以供体特异性抗体的产生为特征。这些抗体可能是由CD4+ T细胞依赖的B细胞对同种异体移植物的反应引起的。然而，这种机制的直接证据很少。另一方面，调节性T细胞的缺乏导致人类异常的B细胞激活和自身抗体的产生。自体抗体在移植受者中普遍存在。众所周知，用于预防排斥反应的免疫抑制药物会直接损害Treg的功能。我们认为，CHR是由Treg缺乏导致外周B细胞的失调和伴随的同种异体抗体和自身抗体的发展引起的。在一项综合分析中，我们的研究将确定Treg缺乏以及同种异体抗体和自身抗体的共同发展是否与肾移植受者的CHR相关。我们还将研究Treg缺乏诱导CHR患者B细胞失调的可能机制。验证我们提出的模型的实验将在3个具体目标中进行：Aim-1。目的：探讨CHR是否与自身抗体滴度增高有关。利用蛋白质组学阵列方法，我们将确定CHR抗体反应的自身抗原靶点。然后，我们将评估针对这些靶点的自身抗体以及与CHR发生相关的同种异体抗体的共同发展。Aim-2。为了确定CHR是否与Treg缺乏相关，对患者样本中Treg群体的表型和分子评估将确定CHR是否与这些细胞的数量和频率减少相关。体外细胞检测也将用于评估CHR是否与Treg抑制活性降低相关。Aim-3。明确B细胞在CHR中的失调机制，对B细胞亚群的表型和功能评估将决定CHR患者的失调是由于B细胞发育缺陷还是外周B细胞活化加剧。体外细胞实验将研究Treg控制B细胞活化的细胞机制。最后，我们将研究B细胞在CHR患者的移植物中直接分化的可能性。

DESCRIPTION (provided by applicant): The number of kidney transplants performed every year in the US is increasing. While early graft survival has improved over the past decade, long-term survival has not significantly changed during the same time and remains unsatisfactory. Accumulating evidence suggests that chronic humoral rejection (CHR) is responsible for a large proportion of late kidney graft losses. Seemingly, CHR does not respond well to conventional immunosuppressive therapies. A better understanding of the pathophysiology of this complication will lead to the development of new treatments and reduce the rate of rejection. The long-term goal of our proposed research is to understand the immune mechanisms leading to CHR. CHR is characterized by the development of donor specific antibodies. These antibodies presumably result from a CD4+ T cell dependent B cell response directed to the allograft. Yet, direct evidence of this mechanism is scarce. On the other hand, deficiency in regulatory T cells leads to aberrant B cell activation and autoantibody production in humans. Autoantibodies are prevalent in transplant recipients. It is also known that immunosuppressive drugs used to prevent rejection, directly impair Treg function. We propose that CHR results from Treg deficiency leading to the deregulation of peripheral B cells and concomitant development of allo- and autoantibodies. In a comprehensive analysis, our studies will determine whether Treg deficiency and the co-development of allo- and autoantibodies correlate with CHR in kidney transplant recipients. We will also examine possible mechanisms whereby Treg deficiency induces B cells deregulation in patients with CHR. Experiments to verify our proposed model will be carried out in 3 specific aims: Aim-1. To examine whether CHR is associated with increased autoantibody titers. Utilizing a proteomics array approach, we will identify autoantigenic targets of antibody responses in CHR. We will then assess the co development of autoantibodies to these targets as well as alloantibodies in correlation with the occurrence of CHR. Aim-2. To determine whether CHR correlates with Treg deficiency Phenotypic and molecular assessment of Treg populations in patient samples will determine whether CHR correlates with reduced numbers and frequencies of these cells. In vitro cell based assays will also be used to assess whether CHR correlates with reduced Treg suppressive activity. Aim-3. To define mechanisms of B cell deregulation in CHR Phenotypic and functional assessment of B cell subsets will determine whether deregulation in CHR patients is due to defective B cell development or exacerbated B cell activation in the periphery. In vitro cell based assays will investigate the cellular mechanisms whereby Treg control B cell activation. Lastly, we will examine the possibility that B cells differentiate directly in the graft in patients with CHR.