Targeting Mast Cells in Post-Traumatic Joint Rehabilitation and Osteoarthritis

许多退伍军人和平民遭受创伤性关节损伤，这往往导致康复情况不佳。 受伤关节的结果、关节功能障碍和骨关节炎(OA)的发展。现有的治疗方法 关节损伤和骨性关节炎只能缓解症状，对促进愈合或预防骨性关节炎无效。 越来越多的证据表明，关节损伤后的“低级别”炎症与康复效果差有关。 以及创伤后骨性关节炎的最终发展。更好地了解潜在的炎症 靶向异常信号转导通路的机制和药理药物的鉴定 军人、退伍军人和平民创伤性关节损伤的护理和康复。我们的 初步研究提示肥大细胞在关节炎症反应中起关键作用 在促进创伤后骨性关节炎的发展方面也发挥了重要作用。在这项建议中，我们的目的是阐明 肥大细胞在关节损伤后康复效果差和创伤后骨性关节炎的发展中起重要作用。 在骨性关节炎滑膜和创伤后非骨性关节炎关节中检测到肥大细胞，并能够产生 促炎和降解性介质。我们发现包括肥大细胞在内的肥大细胞介质的过度表达 关节损伤或骨性关节炎患者滑膜和滑液中的细胞特异性类胰蛋白酶。来自两个站点的数据 小鼠模型显示，缺乏肥大细胞可减轻与骨性关节炎相关的病理改变，而骨性关节炎的植入 肥大细胞恢复了这种表型。对肥大细胞激活的药物抑制证实了这些结果。 我们的体外研究表明，类胰蛋白酶诱导了几个与OA发病相关的过程：退行性变 关节软骨细胞的凋亡，以及促炎反应和细胞增殖 滑膜成纤维细胞。此外，我们还发现FcεRI、Syk和组胺释放介导的免疫球蛋白E信号转导 HRF参与了创伤后骨性关节炎的发病机制。然而，重要的问题仍然存在。 关于关节创伤后肥大细胞激活的上游机制以及在骨性关节炎中的作用 免疫球蛋白E，以及靶向肥大细胞通路或产物是否可能改善康复和预防OA。我们 假设关节损伤后，Ig E介导的肥大细胞活化涉及FcεRI、Syk和hrf 促进炎症，损害康复，加速骨性关节炎的发展。此外，我们 假设损伤诱导的关节和软骨破坏产物导致IgE反应和/或 激活肥大细胞的HRF的产生，生物标志物可以被识别来指导药理学 以肥大细胞为靶点，促进成功康复，防止创伤后骨性关节炎的发展。 为了验证这些假设，在目标1中，我们建议表征肥大细胞的激活、脱颗粒和 人体关节损伤后、康复和骨关节炎中的生物标记物。在目标2中，我们将描述IgE的特征 关节损伤、康复和骨性关节炎的反应。在目标3中，我们将确定药物靶向的策略 肥大细胞通路在改善关节损伤后康复效果和预防继发性骨关节炎中的作用 内侧半月板(DMM)小鼠模型的失稳。重要的是，Aim 3将专注于FDA批准的 靶向肥大细胞的药物，从而提供了一条快速翻译和评估前景的途径 在促进成功康复结果和预防发展方面有效的候选对象 人类关节损伤后继发性骨性关节炎。如果成功，该提案将阐明肥大细胞的作用 和IgE在关节损伤后骨性关节炎康复结局和发展中的作用(目标1和2)，建立 用于识别可能患有肥大细胞介导的不良康复结果的个体的生物标志物 和创伤后骨性关节炎(目标1和2)，并确定针对肥大的候选药物干预措施 促进成功康复和最佳功能结果的细胞(目标3)。

Many Veterans and civilians sustain traumatic joint injuries, which frequently lead to poor rehabilitation outcomes, joint dysfunction, and development of osteoarthritis (OA) in the injured joint. Existing treatments for joint injury and OA only alleviate symptoms, and are ineffective in promoting healing or preventing OA. Increasing evidence implicates “low-grade” inflammation following joint injury in poor rehabilitation outcomes, and in the eventual development of post-traumatic OA. A better understanding of the underlying inflammatory mechanisms and identification of pharmacologic agents that target the dysregulated pathways could transform the care and rehabilitation for military personnel, Veterans, and civilians with traumatic joint injuries. Our preliminary studies suggest a critical role for mast cells in mediating inflammatory responses following joint injury and in promoting the development of post-traumatic OA. In this proposal, we aim to elucidate the roles of mast cells in poor rehabilitation outcomes following joint injury and in the development of post-traumatic OA. Mast cells are detected in OA synovium as well as in post-trauma non-OA joints, and are capable of producing pro-inflammatory and degradative mediators. We found overexpression of mast cell mediators, including mast cell-specific tryptases, in synovial membranes and fluids from individuals with joint injury or OA. Data from two mouse models indicated that lack of mast cells attenuated OA-related pathologies, whereas engraftment of mast cells restored this phenotype. Pharmacologic inhibition of mast cell activation confirmed these results. Our in vitro studies showed that tryptase induces several processes integral to OA pathogenesis: degeneration of human cartilage, apoptosis of articular chondrocytes, and pro-inflammatory responses and proliferation of synovial fibroblasts. Further, we found that IgE signaling mediated by FcεRI, Syk, and histamine-releasing factor (HRF) is involved in the pathogenesis of post-traumatic OA. Nevertheless, important questions remain about the upstream mechanisms underlying mast cell activation following joint trauma and in OA, the role of IgE, and whether targeting mast cell pathways or products might improve rehabilitation and prevent OA. We hypothesize that following joint injury, IgE-mediated activation of mast cells involving FcεRI, Syk, and HRF promotes inflammation, which impairs rehabilitation and accelerates the development of OA. Further, we hypothesize that injury-induced joint and cartilage breakdown products lead to an IgE response and/or production of HRF that activates mast cells, and that biomarkers can be identified to guide pharmacologic targeting of mast cells to promote successful rehabilitation and prevent the development of post-traumatic OA. To test these hypotheses, in Aim 1, we propose to characterize mast cell activation, degranulation, and biomarkers in human joints post-injury, in rehabilitation, and in OA. In Aim 2, we will characterize the IgE response in joint injury, rehabilitation, and OA. In Aim 3, we will identify strategies that pharmacologically target mast cell pathways to improve rehabilitation outcomes and to prevent secondary OA following joint injury in the destabilization of the medial meniscus (DMM) mouse model. Importantly, Aim 3 will focus on FDA-approved drugs that target mast cells, thereby providing a path for rapid translation and evaluation of promising candidates for efficacy in promoting successful rehabilitation outcomes and preventing development of secondary OA following joint injury in humans. If successful, the proposal will elucidate the roles of mast cells and IgE in rehabilitation outcomes and development of OA following joint injury (Aims 1 and 2), establish biomarkers to identify individuals who are likely to suffer from mast-cell-mediated poor rehabilitation outcomes and post-traumatic OA (Aims 1 and 2), and identify candidate pharmacologic interventions that target mast cells to promote successful rehabilitation and optimal functional outcomes (Aim 3).