Pathogenesis of lung injury mediated by lung-restricted antibodies

项目总结 肺限制性抗体(LRA)抗非多形性肺自身抗原、V型胶原(COLV)和K- α1微管蛋白(KAT)存在于超过三分之一的接受肺移植的患者中。因为这些自我- 抗原在所有人类中都有表达，受体中先前存在的LRA可以与暴露的同源抗原结合 在新移植的肺里。事实上，上帝抵抗军已成为 原发移植物功能障碍是肺移植术后早期死亡的主要原因。 在小鼠模型中，LRA与严重的同种异体肺移植损伤有因果关系，而在患者中，它们是相关的 随着供者特异性同种异体免疫反应的发展。然而，其背后的机制 致病性尚未阐明。鉴于上帝抵抗军的高患病率及其与 同种异体移植损伤，阐明这些机制应导致相关策略，以改善肺移植 生死存亡。我们已报道LRA介导的同种异体移植物损伤与补体沉积有关。 中性粒细胞渗入。然而，我们不了解上帝抵抗军驱动补体的机制 无论是中性粒细胞沉积还是中性粒细胞募集，都不是LRA介导的损伤所必需的。因为这些肺 自身抗原位于间质间隙，也不清楚循环中的LRA如何获得这些 抗原。我们最近报道了脾来源的Ly6ChighCCR2+经典单核细胞(CM)是 在缺血-再灌注损伤后被重新招募到肺，在那里它们需要打开内皮紧密 通过激活白介素1β受体(IL1R)进行连接。与这些发现一致的是，我们的初步数据显示 来自IL1R-/-供者的同基因或同种异体肺移植可免受LRA介导的肺移植损伤。我们 也有报道称Ly6ClowCCR2-肺血管内非经典单核细胞(NCM)是必需的 中性粒细胞重新聚集到供体肺。我们新的初步数据显示，上帝抵抗军与他们的 同种抗原可促进中性粒细胞趋化因子CXCL2从人和小鼠NCM中释放。 因此，我们假设lra的外渗到肺间质需要依赖于IL1β。 脾来源的经典单核细胞开放内皮细胞紧密连接，并与同源细胞结合 间质中的抗原，交联型LRA激活补体以及供体来源的NCM促进 急性同种异体肺损伤。因此，我们将确定1)脾CM是否允许LRA进入 经脾教育后打开内皮紧密连接的肺，2)补充途径 负责LRA介导的损伤以及补体激活的机制，以及3)是否 LRA对供体NCM的Toll受体非依赖性激活可导致中性粒细胞募集和肺损伤。 这些实验的总体目标是为LRA的生物学提供新的见解，并在临床上介绍 通过药理抑制CM-1抑制移植后肺损伤的适用策略 衍生的IL1β(目标1)、补体(目标2)或供体NCM的缺失(目标3)。

PROJECT SUMMARY Lung-restricted antibodies (LRA) against non-polymorphic lung self-antigens, collagen type V (COLV) and K- alpha1 tubulin (KAT), are present in over a third of patients undergoing lung transplantation. Since these self- antigens are expressed in all humans, pre-existing LRA in the recipient can bind to cognate antigens exposed in the freshly transplanted lungs. Indeed, LRA have emerged as the predominant risk factor for the development of primary graft dysfunction, the principal cause of early mortality following lung transplantation. In murine models, LRA are causally linked to severe lung allograft injury, and in patients they are associated with development of donor specific alloimmune responses. However, the mechanisms underlying their pathogenicity have not been elucidated. Given the high prevalence of LRA and their causal association with allograft injury, delineating these mechanisms should lead to relevant strategies to improve lung transplant survival. We have reported that LRA mediated allograft injury is associated with the deposition of complement and neutrophil infiltration. However, we do not understand the mechanisms by which LRA drive complement deposition or neutrophil recruitment, nor whether either is necessary for LRA-mediated injury. Since these lung self-antigens are located in the interstitial spaces, it is also unclear how circulating LRA gain access to these antigens. We have recently reported that spleen-derived Ly6ChighCCR2+ classical monocytes (CM) are recruited to the lungs following ischemia-reperfusion injury where they are necessary to open endothelial tight junctions by activating IL1β receptors (IL1R). Consistent with these findings, our preliminary data shows that syngeneic or allogeneic lung grafts from Il1r-/- donors are protected from LRA-mediated lung graft injury. We have also reported that Ly6ClowCCR2- pulmonary intravascular non-classical monocytes (NCM) are necessary for neutrophil recruitment into the donor lung. Our new preliminary data suggest that LRA cross-linked to their cognate antigens can enhance release of the neutrophil chemoattractant CXCL2 from human and murine NCM. Therefore, we hypothesize that extravasation of LRA into the lung interstitium requires IL1β-dependent opening of endothelial tight junctions by spleen-derived classical monocytes and, upon binding to cognate antigens in the interstitium, cross-linked LRA activate complement as well as donor-derived NCM to promote acute lung allograft injury. Accordingly, we will determine 1) whether splenic CM allow passage of LRA into the lungs by opening endothelial tight junctions after being educated in the spleen, 2) which complement pathway is responsible for LRA-mediated injury as well as the mechanisms of complement activation, and 3) whether toll-receptor independent activation of donor NCM by LRA leads to neutrophil recruitment and lung injury. Overall goal of these experiments is to provide novel insights into the biology of LRA and introduce clinically applicable strategies to inhibit lung injury following transplantation through pharmacological inhibition of CM- derived IL1β (Aim 1), complement (Aim 2), or deletion of donor NCM (Aim 3).