Modulation of Inflammation in Osteoarthritis via CD14-mediated pattern recognition

摘要 骨性关节炎(OA)是导致成年人残疾的主要原因，导致慢性进行性关节疼痛和组织 整个关节都受损了。目前还没有有效的药物治疗来预防进行性关节 骨性关节炎的恶化、疼痛和残疾特征。尽管我们知道发炎和骨骼- 重塑是骨性关节炎疼痛和病理的主要驱动因素，目前还不清楚直接通过哪些分子途径 推动慢性骨性关节炎疼痛和疾病进展，或者是治疗发展的关键目标。我们的实验室有 研究表明，巨噬细胞表达的炎性模式识别受体CD14的缺乏与 其他类型的髓系细胞对骨性关节炎相关的骨重建和疼痛相关的关节功能障碍具有保护作用 小鼠膝关节损伤后。在患者中，CD14在关节液中升高，并与关节内相关 巨噬细胞浸润以及疼痛严重程度。该受体促进Toll样受体(TLR)信号转导。 TLRs是先天免疫感受器，是慢性炎症反应的重要初始触发因素 非感染性组织损伤。此外，我们的团队最近证明了TLR信令对于 通过直接刺激膝部疼痛传递(伤害性)神经元，发展小鼠膝骨性关节炎疼痛 支配膝关节的背根节(DRG)。在这个提议中，我们将检验CD14在 包括巨噬细胞在内的髓系细胞促进骨性关节炎疼痛相关病理(骨重塑和 炎症)，而CD14也通过直接敏化支配骨性关节炎的神经元而增加骨性关节炎的疼痛 关节炎关节。我们将利用体外技术和小鼠内侧半月板失稳(DMM) 目的：了解CD14在骨性关节炎发病机制中的作用。 关节组织中的炎症。具体地说，在目标1中，我们将使用多学科方法来确定如何 CD14的遗传缺陷改善了骨关节炎进展过程中的炎症和骨重塑，使用 数字万用表型号。我们将确定髓系细胞在炎症和骨重建中的作用。 用骨髓(BM)嵌合小鼠建立模型。最后，我们将检测CD14在细胞分化中的作用。 驱动骨重建的细胞(破骨细胞)和来自髓系的炎性疼痛介质的产生 单元类型。在目标2中，我们将描述CD14在TLR介导的DRG神经元激活和关节中的作用 疼痛。我们将使用与OA相关的TLR刺激来评估体外DRG反应，比较WT和 CD14缺陷细胞。此外，我们还将比较关节内注射TLR刺激后的疼痛反应，以及 预计在CD14缺陷株中，DRG反应和疼痛都将被钝化。最后，在目标3中，我们将 测试CD14的药理学靶向是否可以减轻DMM诱导的损伤后的OA进展和疼痛。 这项研究将确定分子和细胞框架，以设计未来的抗炎药物 针对骨性关节炎的治疗针对CD14和TLR介导的机制。

ABSTRACT Osteoarthritis (OA) is a leading cause of disability in adults, causing chronic progressive joint pain and tissue damage throughout the joint. No current medical treatments are effective at preventing the progressive joint deterioration, pain and disability characteristic of OA. Although it is known that inflammation and bone- remodeling are major drivers of OA pain and pathology, it is not yet clear which molecular pathways directly drive chronic OA pain and disease progression or are key targets for therapeutic development. Our lab has shown that deficiency of CD14, an inflammatory pattern-recognition receptor expressed by macrophages and other myeloid cell types, protects against OA-associated bone-remodeling and pain-related joint dysfunction after knee injury in mice. In patients, CD14 is increased in joint fluid and associated with intra-articular macrophage infiltration as well as pain severity. This receptor facilitates Toll-like receptor (TLR) signaling. TLRs are innate immune sensors which are important initial triggers of chronic inflammation in response to non-infectious tissue damage. In addition, our team has recently demonstrated that TLR-signaling is critical to development of knee OA pain in mice, via direct stimulation of pain-transmitting (nociceptive) neurons in the dorsal root ganglia (DRG) that innervate the knee. In this proposal, we will test the hypothesis that CD14 on myeloid cells including macrophages promotes OA pain-related pathology (bone remodelling and inflammation), while CD14 also augments OA pain by directly sensitizing neurons innervating the arthritic joint. We will utilize in vitro techniques and the murine destabilization of the medial meniscus (DMM) model of OA, to understand the cellular and molecular mechanisms by which CD14 drives OA pathology and inflammation in joint tissues. Specifically, in Aim 1 we will use a multi-disciplinary approach to determine how genetic deficiency of CD14 modifies inflammation and bone-remodeling during progression of OA, using the DMM model. We will determine the contribution of myeloid cells to inflammation and bone-remodeling in the model by using bone marrow (BM) chimeric mice. Lastly, we will test the effects of CD14 on differentiation of cells that drive bone-remodeling (osteoclasts) and production of inflammatory mediators of pain from myeloid cell types. In Aim 2 we will characterize effects of CD14 on TLR-mediated DRG neuronal activation and joint pain. We will use TLR stimuli with relevance to OA to evaluate DRG responses in vitro, comparing WT and CD14-deficient cells. We will additionally compare pain responses to injection of TLR-stimuli into the joint, and expect that both DRG responses and pain will be blunted in the CD14 deficient strain. Finally, in Aim 3 we will test whether pharmacological targeting of CD14 reduces OA progression and pain after DMM-induced injury. This study will then specify the molecular and cellular framework to design future anti-inflammatory therapeutics for OA aimed at CD14- and TLR-mediated mechanisms.