Complement driven innate and adaptive autoreactivity in lung transplantation

摘要：闭塞性细支气管炎（OB）是肺移植（LTx）后晚期死亡的主要原因， 改善长期成果的主要障碍。越来越多的证据表明， 自身免疫在移植排斥发病机制中的作用。肺气肿是LTx的主要适应症， 显示出表达广谱的细胞外基质自身反应性抗体和T细胞， 胶原蛋白、弹性蛋白和核心蛋白聚糖，其对Tx后结果的影响尚不清楚。在这里，我们将使用鼠标 肺气肿和原位LTx模型，以研究临床相关场景中的LTx结局。的 这些研究的科学前提是确定移植前自身反应性免疫是否由 肺气肿，促进Tx后损伤，导致加重的缺血再灌注损伤（IRI）和OB。 LTx的最早损伤是IRI的结果，其严重程度被认为会导致 加速发作OB。缺血损伤后再灌注导致表达的新表位暴露 对应激/损伤细胞的天然自身反应性IgM抗体识别，其结合并激活C系统， 导致炎症和损伤。我们已经确定膜联蛋白IV是一种损伤特异性新表位， 在缺血性移植物中，并且已经表明这种新表位结合天然IgM，激活C并促进 IRI。通过抗膜联蛋白IV单链抗体（B4 scFv），我们已经验证了膜联蛋白IV作为靶点， C抑制向鼠同种异体移植物的治疗性递送。这有很多治疗上的好处 用于在LTx接受者中保护免受IRI的新表位靶向方法：1.它将瞄准近端事件， 补体激活，2.靶向载体本身通过阻断结合而有助于治疗活性。 补体激活抗体，和3.会抑制局部的C活化，这会损害T细胞活化。 我们的工作假设是，移植前对细胞外基质靶点的自身反应性在早期恶化， 移植物损伤，从而促进早发性OB。我们提出，新表位IgM移植物靶向C抑制剂将 协同抑制适应性自身抗体效应子功能，并降低移植物内自身反应性T细胞活性。 我们提出以下具体、独立但相互关联的目标。1.确定补体介导的 影响细胞外基质自身反应性免疫诱导的急性肺移植物损伤的效应子功能。 在这里，我们将确定同种型和表型的自身反应性抗体和T细胞，促进损伤 移植后并进一步剖析诱导移植物损伤的补体效应子功能，和2.在 小鼠OB模型，确定香烟烟雾诱导的自身免疫是否加重IRI和慢性炎症。 以补体依赖性方式移植后的排斥反应。我们将把肺移植到 肺气肿小鼠（由香烟烟雾暴露诱导）使用同种异体OB模型，并确定 长期暴露于CS是否会导致不良结局，并进一步研究C介导的 在Tx过程早期发生的炎症和损伤影响IRI和OB。 !

Abstract: Obliterative bronchiolitis (OB) is the leading cause of late death after lung transplantation (LTx) and the principle unmet obstacle to improved long-term outcomes. Increasing evidence indicates a role for recipient autoimmunity in the pathogenesis of graft rejection. Emphysema, a principle indication for LTx, has been shown to express a wide-spectrum of extracellular matrix autoreactive antibodies and T cells directed towards collagen, elastin, and decorin, the impact of which on post-Tx outcomes is unknown. Here we will utilize mouse models of emphysema, and orthopic LTx, to investigate LTx outcomes in a clinically relevant scenario. The scientific premise of these studies is to determine if pre-transplant autoreactive immunity induced by emphysema, promotes post-Tx injury that leads to exacerbated ischemia reperfusion injury (IRI) and OB. The earliest injury to the LTx occurs as a consequence of IRI, the severity of which is thought to lead to accelerated onset OB. Ischemic insult followed by reperfusion leads to the exposure of neoepitopes expressed on stressed/injured cells recognized by natural self-reactive IgM Abs, which bind and activate the C system, resulting in inflammation and injury. We have identified annexin IV as an injury-specific neoepitope expressed in ischemic transplant grafts, and have shown that this neoepitope binds natural IgM, activates C and promotes IRI. By means of an anti-annexin IV single chain Ab (B4scFv), we have validated annexin IV as a target for the therapeutic delivery of C inhibition to murine allografts. There are a number of therapeutic benefits of this neoepitope targeting approach for protection against IRI in a LTx recipient: 1. It will target the proximal event in complement activation, 2. The targeting vehicle itself contributes to therapeutic activity by blocking the binding of complement activating antibodies, and 3. Will inhibit C activation locally, which will impair T cell activation. Our working hypothesis is that pre-transplant autoreactivity to extracellular matrix targets exacerbates early graft injury, thus promoting early onset OB. We propose that neoepitope IgM graft-targeted C inhibitors will synergize to inhibit adaptive autoantibody effector functions, and reduce intragraft autoreactive T cell activity. We propose the following specific, independent, but interrelated aims. 1. Determine the complement-mediated effector functions that contribute to extracellular matrix autoreactive immunity induced acute lung graft injury. Here we will determine the isotype and phenotype of autoreactive antibodies and T cells that promote injury post transplantation and further dissect the complement effector functions that induce graft damage, and 2. In a murine model of OB, determine whether cigarette smoke-induced autoimmunity exacerbates IRI and chronic rejection following transplantation in a complement-dependent manner. We will transplant lungs into emphysematous mice (induced by cigarette smoke exposure) using allogeneic models of OB and determine whether prolonged CS exposure results in poorer outcomes, and further investigate how C-mediated inflammation and injury occurring early in the Tx process influences IRI and OB. !