Allograft Inflammatory Factor in Transplant Vasculopathy

移植动脉硬化是移植一年后移植器官衰竭的主要原因。尽管其详细的发病机制尚不清楚，但临床和实验室研究表明，移植动脉硬化源于局部免疫介导的过程，涉及受体单核细胞（巨噬细胞、B淋巴细胞和T淋巴细胞起关键作用）与供体器官血管系统细胞之间的相互作用。同种异体炎症因子（aif-1）是一种携带EF和Ca++结合基元的17 kD蛋白，在大多数正常组织中几乎检测不到。然而，巨噬细胞谱系的表达在同种异体和自身免疫性反应中均显著增加，包括移植心脏血管周围炎症、实验性自身免疫性神经炎和糖尿病前期BB大鼠胰腺炎症。对于aif-1在巨噬细胞活化中的功能及其在移植动脉硬化或其他炎症的发病机制中的具体作用知之甚少。本研究有三个主要目标：描述aif-1离散疾病相关表达模式的分子基础，确定aif-1在巨噬细胞生物学中的作用，并评估其在移植动脉硬化发病机制中的重要性。分子遗传技术，如腺病毒转导和胚胎干细胞的基因靶向，将用于产生具有不同水平的aif-1表达的巨噬细胞。这些细胞的功能将在体外和体内进行测试。aif-1在移植动脉硬化中的重要性将在缺乏aif-1的小鼠同种异体移植研究中进行评估。这项工作可能会改善器官移植的长期预后。控制aif-1表达的遗传元件可能有助于将免疫调节基因产物直接表达到移植器官的炎症部位。aif-1的功能意义可能存在于巨噬细胞中，或存在于它们对其他炎症细胞的调节中；aif-1的表达如何影响免疫反应可能指向参与移植动脉硬化发展的新调控途径。

Transplant arteriosclerosis is the major cause of graft organ failure after the first year of transplantation. Although its detailed pathogenesis remains unclear, clinical and laboratory studies indicate that transplant arteriosclerosis stems from a local, immune-mediated process involving interactions between the recipient's mononuclear cells, with critical roles for macrophages and B and T lymphocytes, and cells of the donor organ's vascular system. Allograft inflammatory factor (aif-1), a 17 kD protein bearing an EF hand Ca++-binding motif, is barely detectable in most normal tissues. However, its expression by cells of macrophage lineage increases markedly in both allo- and autoimmune reactions, including perivascular inflammation in transplanted hearts, experimental autoimmune neuritis, and the inflamed pancreas of prediabetic BB rats. Very little is known about the function of aif-1 in macrophage activation or its specific role in the pathogenesis of transplant arteriosclerosis or other inflammatory conditions. This proposal has three major goals: to delineate the molecular basis for the discrete disease-associated pattern of expression of aif-1, to define the role of aif-1 in macrophage biology, and to assess its importance in the pathogenesis of transplant arteriosclerosis. Molecular genetic techniques such as adenoviral transduction and gene targeting of embryonic stem cells will be used to produce macrophages with substantially different levels of aif-1 expression. Function of these cells will be tested both in vitro and in vivo. The importance of aif-1 in transplant arteriosclerosis will be assessed in allograft transplantation studies with mice lacking aif-1. This work may lead to improved longterm outcomes for organ transplantation. The genetic elements controlling aif-1 expression may be useful to direct expression of immunoregulatory gene products to sites of inflammation in transplanted organs. The functional significance of aif-1 likely resides in macrophages, or in their regulation of other inflammatory cells; how aif-1 expression affects the immune response may point to new regulatory pathways involved in the development of transplant arteriosclerosis.