Understanding A Molecular Cascade That Drives Neutrophil Mediated Pathology In Arthritis

了解推动中性粒细胞介导的关节炎病理的分子级联反应 类风湿性关节炎(RA)是一种常见的滑膜关节慢性疾病，以痛性关节丧失为特征 由于不受抑制的炎症和进行性骨质侵蚀而导致的行动不便。疾病病因学很差 在许多RA患者中，现有的治疗方法无法控制疾病症状， 强调了确定新的治疗靶点的迫切需要。RA的一个关键事件是 白细胞，如中性粒细胞，进入关节，在那里它们启动和维持炎症并促进 类风湿关节炎早期的骨质侵蚀。虽然健康的滑液是无细胞的，但最丰富的细胞类型 在发炎的滑液中发现了激活的中性粒细胞。 吞噬和细胞运动蛋白-1(ELMO1)是肌动蛋白细胞骨架动力学的调节因子。 死亡细胞的吞噬和淋巴细胞的迁移。我们证明了ELMO1-/-小鼠 在两种炎症性关节炎模型中，疾病显著减轻，这两种模型具有许多与人类RA相同的特征，以及 在确定的疾病期间删除ELMO1可以改善关节炎症状和疾病解决。我们 发现抗病是由于中性粒细胞中特定的ELMO1功能，而ELMO1的丢失 显著减弱中性粒细胞的激活和迁移(由参与关节炎的趋化因子诱导)和 减少了中性粒细胞对关节的动员。循环中的ELMO1-/-中性粒细胞降低了细胞表面的水平 拴系分子CD62L和减少趋化因子诱导的黏附/迁移促进的暴露 整合素CD11b。这些数据表明，ELMO1功能可能是中性粒细胞的多个步骤所必需的 募集级联以增强中性粒细胞向关节的募集。令人惊讶的是，ELMO1的丧失并没有损害 细菌刺激引起的中性粒细胞募集和功能，表明ELMO1的治疗靶点 可以维持正常的病原体清除。最后，与RA相关的SNP rs11984075位于 ELMO1基因与中性粒细胞中ELMO1蛋白和CD62L的升高相关，提示 携带rs11984075 SNP的RA患者可以从针对ELMO1的治疗方法中受益。我们假设 ELMO1在炎症性关节炎的组织/刺激特异性中性粒细胞募集和病理中起作用。 在这项提案中，我们将解决三个具体目标：1.测试刺激或组织是否需要ELMO1 特定的中性粒细胞募集。2.检测ELMO1是否通过CD62L/L-选择素促进中性粒细胞黏附 3.确定ELMO1 SNP rs11984075提高蛋白质水平的机制，并测试一种抑制 ELMO1在关节炎中。这项建议意义重大，因为它将加深我们对ELMO1在 中性粒细胞介导的类风湿性关节炎的病理变化，并可能导致新的诊断工具和 治疗策略。我们的建议是创新的，因为它将推动ELMO1生物学和 将为科学界和研究中性粒细胞功能产生新的工具。

UNDERSTANDING A MOLECULAR CASCADE THAT DRIVES NEUTROPHIL MEDIATED PATHOLOGY IN ARTHRITIS Rheumatoid arthritis (RA) is a frequent chronic disease of the synovial joints characterized by painful loss of mobility due to unrestrained inflammation and progressive bone erosion. Disease etiology is poorly characterized, and the available therapeutic approaches fail to control disease symptoms in many RA patients, highlighting the critical need for identification of new therapeutic targets. A key event in RA is the influx of leukocytes, such as neutrophils, into the joints, where they initiate and sustain inflammation and contribute to bone erosion from the early stages of RA. While healthy synovial fluid is acellular, the most abundant cell type found in the inflamed synovial fluid is the activated neutrophil. Engulfment and cell motility protein-1 (ELMO1) is a regulator of actin cytoskeleton dynamics during phagocytosis of dying cells and migration of lymphocytes. We demonstrated that Elmo1–/– mice develop significantly milder disease in two models of inflammatory arthritis that share many features with human RA, and that deletion of Elmo1 during established disease could improve arthritis symptoms and disease resolution. We found that disease resistance is due to specific ELMO1 function in neutrophils, and that loss of ELMO1 significantly attenuated neutrophil activation and migration (induced by chemokines involved in arthritis) and reduced neutrophil mobilization to the joints. Circulating Elmo1–/– neutrophils had reduced cell surface levels of the tethering molecule CD62L, and reduced chemokine-induced exposure of the adhesion/migration-promoting integrin CD11b. These data suggest that ELMO1 function may be required for multiple steps of the neutrophil recruitment cascade to enhance neutrophil recruitment into joints. Surprisingly, loss of ELMO1 did not impair neutrophil recruitment and function elicited by bacterial stimuli, indicating that therapeutic targeting of ELMO1 could maintain normal pathogen clearance. Finally, the RA-associated SNP rs11984075, located in an intron of the ELMO1 gene, correlates with increased ELMO1 protein and elevated CD62L in neutrophils, suggesting that RA patients with SNP rs11984075 could benefit from therapeutic approaches targeting ELMO1. We hypothesize that ELMO1 contributes to tissue/stimulus-specific neutrophil recruitment and pathology in inflammatory arthritis. In this proposal, we will address three specific aims: 1. Test if ELMO1 is required for stimulus- or tissue- specific neutrophil recruitment. 2. Test if ELMO1 promotes neutrophil adhesion through CD62L/L-selectin, and 3. Identify the mechanism by which ELMO1 SNP rs11984075 elevates protein levels and test an inhibitor of ELMO1 in arthritis. This proposal is significant because it will further our understanding of the role of ELMO1 in neutrophil-mediated pathology in rheumatoid arthritis and could lead to the discovery of new diagnostic tools and therapeutic strategies. Our proposal is innovative because it will advance new concepts in ELMO1 biology and will generate new tools for the scientific community and for studying neutrophil functions.