Pathogenesis of lung injury mediated by lung-restricted antibodies

原发移植物功能障碍(PGD)影响超过50%的受者在肺后24-72小时内 移植。PGD是肺移植后死亡的主要风险，与移植相关的多器官 功能障碍和慢性肺移植排斥反应。由于肺移植越来越多地被用作挽救生命的 治疗慢性肺部疾病和急性呼吸窘迫综合征，缓解PGD 是改善移植结果的多管齐下战略的关键组成部分。 在一项前瞻性的临床研究中，我们发现超过30%的接受肺移植的患者有肺- 针对自身抗原、V型胶原和k-α1微管蛋白的限制性自身抗体(LRA) 与PGD的发生发展有关。既往存在的LRA与补体激活、中性粒细胞 复张、PaO2/FiO2降低和肺损伤加重，这些都是PGD的临床特征。在并行工作中，我们 确认供者来源的非经典单核细胞(NCM)在肺移植中的重要作用 在PGD的发生发展过程中进行灌流。供体来源的NCM正义损伤相关分子模式 (DAMPS)通过TLR2/4的冗余信号释放CXCL2和其他直接招募 中性粒细胞向同种异体肺移植及激活供者肺泡巨噬细胞募集受者经典单核细胞 储存在脾里。在迁移到肺移植后，受体经典单核细胞(CM)通透 肺内皮细胞和放大中性粒细胞外溢到肺泡腔。我们出版的和 初步数据提示LRA、供体来源的NCM和受者来源的CM之间存在重要的相互作用 确定肺移植后肺损伤的严重程度。具体地说，我们发现LRA绑定FC 供体来源的NCM上的受体促进其在同种异体移植物中的保留和激活。这增强了 CM在同种异体移植物中的募集，从而释放IL-1。IL-1对血管内皮细胞通透性的影响 允许LRA进入肺间质，并促进中性粒细胞迁移到肺泡腔。此外, CM释放基质金属蛋白酶-8(MMP8)，裂解细胞外基质蛋白释放 隔离的自身抗原并暴露其免疫原性表位，使渗出的LRA形成 免疫复合体。由此产生的免疫复合体激活补体，加剧了第一次肺损伤 肺移植后24小时。进一步的初步数据表明，LRA免疫复合物激活了供体 衍生的NCM释放CXCL2并促进中性粒细胞募集，途径需要Src，PI3K和 BTK但不依赖于由DAMPS激活的TLR2/4/MyD88通路，导致迟发性肺损伤。 移植后48~72小时。我们将测试LRA与供体来源的NCM相互作用的假设 受体CM通过补体依赖和非依赖途径加重PGD。目标1.确定 LRA激活NCM的机制。目的2.确定IL-1和MMP8释放的作用 从受体CM分离的自身抗原的裂解及其与LRA的结合。

Primary graft dysfunction (PGD) affects over 50% of recipients within the first 24-72 hours after lung transplantation. PGD is the dominant risk for post-lung transplant mortality, transplant-associated multi-organ dysfunction, and chronic lung allograft rejection. Since lung transplantation is increasingly utilized as a life-saving treatment for both chronic lung diseases as well as acute respiratory distress syndrome, mitigation of PGD represents a critical component of a multi-pronged strategy to improve transplant outcomes. In a prospective clinical study, we found that over 30% of patients undergoing lung transplantation have lung- restricted autoantibodies (LRA) against self-antigens, collagen type V and k-alpha 1 tubulin, which was strongly associated with the development of PGD. Pre-existing LRA is associated with complement activation, neutrophil recruitment, a lower PaO2/FIO2 and worsened lung injury, all clinical hallmarks of PGD. In parallel work, we identified an important role for donor derived non-classical monocytes (NCM) that are retained in the lung grafts after perfusion in the development of PGD. Donor derived NCM sense damage associated molecular patterns (DAMPs) via redundant signaling through TLR2/4 to release CXCL2 and other cytokines that directly recruit neutrophils to the allograft and activate donor alveolar macrophages to recruit recipient classical monocytes stored in the spleen. Upon migration to the lung graft, the recipient classical monocytes (CM) permeabilize the pulmonary endothelium and amplify the extravasation of neutrophils to the alveolar space. Our published and preliminary data suggest important interactions between LRA, donor derived NCM and recipient derived CM in determining the severity of lung injury after lung transplantation. Specifically, we found that LRA bind Fc receptors on donor derived NCM to promote their retention in the allograft and activation. This enhances the recruitment of CM to the allograft which release IL-1. Permeabilization of the endothelium in response to IL-1 allows LRA access to the lung interstitium and promotes neutrophil migration into the alveolar space. In addition, CM release matrix metalloproteinase-8 (MMP8), which cleaves extracellular matrix proteins to release sequestered self-antigens and expose their immunogenic epitopes, enabling the extravasated LRA to form immune complexes. The resulting immune complexes activate complement to exacerbate lung injury in the first 24 hours after lung transplantation. Further preliminary data suggest LRA immune complexes activate donor derived NCM to release CXCL2 and promote neutrophil recruitment via a pathway that requires Src, PI3K and BTK but is independent of the TLR2/4/MyD88 pathway activated by DAMPs, resulting in delayed lung injury in the 48 to 72 hours after transplant. We will test the hypothesis that LRA interact with donor derived NCM and recipient CM to worsen PGD via complement dependent and independent pathways. Aim 1. To determine the mechanisms through which LRA activate NCM. Aim 2. To determine the role of IL-1 and MMP-8 released from recipient CM in the cleavage of sequestered self-antigens and their binding to LRA.