Mechanisms of GalTKO Lung Xenograft Injury

GalTKO 肺异种移植损伤的机制

• 批准号: 6987448
• 负责人: Richard N Pierson
• 金额: $ 22.37万
• 依托单位: UNIVERSITY OF MARYLAND BALTIMORE
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-09-30 至 2010-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6987448
• 关键词: baboons; cell surface receptors; clinical research; complement inhibitors; cooperative study; decay accelerating factor; genetically modified animals; human subject; lung transplantation; platelets; swine; thrombin; thromboplastin; transplant rejection; transplantation immunology; xenotransplantation

DESCRIPTION: Antibodies directed at various targets (especially Gal al,3Gal) and complement are pivotal mediators of hyperacute rejection of the heart, lung, and other organs. However in pig-to-human and pig-to-non-human primate models, we have consistently found that potent complement regulation coupled with efficient removal of anti-pig antibody is associated with rapid dysfunction of lung xenografts. Thus hyperacute lung rejection (HALR) is mediated by mechanisms in addition to those that cause hyperacute rejection of other organs. This paradigm is reinforced by the preliminary studies, where three GalT-KO swine lungs perfused ex vivo retained their function for an average of 2 hours (60, 134, and 170 minutes), far longer than controls (<10 minutes). Failure was due to sudden, rapid increase in pulmonary vascular resistance. Although biopsies obtained at 10 and 30 minutes of perfusion were histologically unremarkable, intravascular thrombi and capillary congestion were observed at graft failure, despite anticoagulation with high-dose heparin. Coagulation pathway activation (Fl+2) was delayed but not prevented, platelet activation (thrombospondin release) was not attenuated, and over 70% of platelets in the perfusate were sequestered in the lung within minutes of initiating perfusion. Complement activation and deposition in the lung, while reduced, were not prevented. Based on these observations and our previous work demonstrating pivotal roles for thrombin, platelets, complement, and pulmonary intravascular macrophages in hyperacute rejection of Gal+ lungs, we hypothesize that dysregulated intravascular coagulation and residual complement activation are the principle cause of acute injury of GalT KO pig lung xenograft. To test this hypothesis, a combination of genetic (GalTKO lungs expressing human tissue factor pathway inhibitor or decay accelerating factor) and pharmacologic approaches (specific platelet receptor, thrombin, or complement inhibitors) will be used in an established ex vivo perfusion model. Approaches that yield optimal lung function ex vivo will then be validated in vivo in a life-supporting pig-to-baboon lung xenograft model. As a result of the studies proposed, we anticipate that hyperacute lung rejection will be successfully prevented for the first time using primarily donor-directed, mechanism-based strategies to consistently achieve life-supporting function of a pig lung in a baboon, allowing subsequent immunologic barriers to be addressed in this organ system.

描述：针对各种靶标（尤其是 Gal al、3Gal）和补体的抗体是心脏、肺和其他器官超急性排斥反应的关键介质。然而，在猪对人和猪对非人灵长类动物模型中，我们一致发现，有效的补体调节加上抗猪抗体的有效去除与肺异种移植物的快速功能障碍有关。因此，除了引起其他器官超急性排斥反应的机制之外，超急性肺排斥反应（HALR）还受到其他机制的介导。 初步研究强化了这一范式，其中三个离体灌注的 GalT-KO 猪肺平均保留其功能 2 小时（60、134 和 170 分钟），远长于对照（<10 分钟）。失败是由于肺血管阻力突然快速增加所致。尽管在灌注10分钟和30分钟时获得的活检在组织学上没有异常，但尽管使用高剂量肝素抗凝，但在移植失败时仍观察到血管内血栓和毛细血管充血。凝血途径激活（F1+2）被延迟但未被阻止，血小板激活（血小板反应素释放）未被减弱，并且灌注液中超过70%的血小板在开始灌注后几分钟内被隔离在肺中。肺中补体的激活和沉积虽然减少，但并未被阻止。基于这些观察结果以及我们之前证明凝血酶、血小板、补体和肺血管内巨噬细胞在 Gal+ 肺超急性排斥反应中的关键作用的工作，我们假设血管内凝血失调和残余补体激活是 GalT KO 猪急性损伤的主要原因肺异种移植物。 为了检验这一假设，将在已建立的离体灌注模型中结合使用遗传（表达人组织因子途径抑制剂或腐烂加速因子的 GalTKO 肺）和药理学方法（特定血小板受体、凝血酶或补体抑制剂）。然后，将在支持生命的猪到狒狒肺异种移植模型中对离体产生最佳肺功能的方法进行体内验证。根据所提出的研究结果，我们预计将首次使用主要以供体为导向、基于机制的策略成功预防超急性肺排斥反应，以持续实现狒狒猪肺的生命支持功能，从而允许随后的免疫学治疗。该器官系统中需要解决的障碍。