Role of CCR2 in osteoarthritis

项目摘要 尽管有证据表明趋化因子在OA关节中增加，但很少有研究检查它们在OA中的作用， 它们促进共同破坏的机制。该提案的目的是确定CC是否- 趋化因子受体2（CCR 2）是OA中关节损伤和疼痛的关键介质。我们的初步研究和 其他人最近的研究表明，CCR 2抑制可以减少OA的结构损伤和疼痛。如果这是真的， 这将是OA管理的重大突破。然而，需要更多的工作来确认这些 研究结果，并确定在OA过程中抑制CCR 2的最佳时间。我们的数据来自一个社区- 基于人OA的队列研究显示，较高的人CCL 2（其结合CCR 2 受体）与5年随访时放射学OA进展相关。利用不稳定的中间层 半月板（DMM）损伤诱导的OA小鼠模型中，我们发现CCL 12的表达（功能性 hCCL 2的同源物），我们以前发现在关节发育中至关重要的CCR 2配体， 关节软骨和骨。关节软骨中的OA变化（软骨损失，MMP 13增加 水平）和骨（骨硬化，骨赘）和疼痛行为得到改善， CCR 2，如果在DMM后的前8周内总共给药4周。然而，如果治疗持续8周或 更多的是，它对随后的结构进展的效果较低，同时仍然抑制疼痛，这表明了一种脱节 结构和疼痛之间的联系。这些数据表明，CCR 2信号传导具有 在OA中的细胞和阶段特异性作用，在针对早期阶段时具有有益效果。我们假设 损伤诱导的关节力学改变在一定时间内上调软骨和骨中的CCR 2通路， 依赖性方式改变两种组织的结构组织，最终导致OA和疼痛。我们 建议确定CCR 2信号在软骨损伤过程中连续时间失调的作用， 年龄诱导的OA，以确定该组织对整个关节退行性变和OA疼痛的贡献 (Aim 1）。我们还将评估成骨细胞表达CCR 2是否有助于关节损伤和疼痛 在损伤诱导的OA期间（目的2）。为了实现这一点，我们将获得一个可诱导的组织特异性CCR 2缺失， 在软骨细胞（目标1）和成骨细胞（目标2）中，通过结合软骨细胞或成骨细胞特异性表达 在分别与聚集蛋白聚糖-CreERT 2或Col 1 α1CreER杂交的CCR 2flox/flox小鼠中，Tam注射CreER。 由于由巨噬细胞和破骨细胞组成的髓样浸润可能导致OA骨的加速形成 重塑可能反映骨损伤，间接地，对软骨稳态，我们也将有条件地 通过使CCR 2flox/flox小鼠与LysMERCre杂交，在巨噬细胞/破骨细胞中抑制CCR 2（Aim 3）。我们将 还评估了每种组织选择性CCR 2缺失所改变的潜在途径。此外，通过使用体外 人原代软骨细胞培养物，我们将研究CCR 2的激活及其 多配体刺激MMP产生。

PROJECT ABSTRACT Despite evidence that chemokines are increased in OA joints, few studies have examined their role in OA and the mechanism by which they promote joint destruction. The goal of this proposal is to determine if the CC- chemokine receptor 2 (CCR2) is a critical mediator of joint damage and pain in OA. Our preliminary studies and recent work by others suggest CCR2 inhibition may reduce both structural damage and pain in OA. If this is true, it would be a major breakthrough in the management of OA. However, more work is needed to confirm these findings and determine the optimal time to inhibit CCR2 during the OA process. Our data from a community- based cohort study of human OA shows that higher baseline serum levels of human CCL2 (which binds CCR2 receptor) correlates with progression of radiographic OA at 5-years follow up. Using the destabilized medial meniscus (DMM) murine model of injury-induced OA, we found that expression of CCL12 (the functional homologue of hCCL2), a CCR2 ligand we have previously found to be critical in joint development, increases in articular cartilage and bone during early OA. OA changes in articular cartilage (cartilage loss, increased MMP13 levels) and bone (bone sclerosis, osteophytes) and pain behavior were ameliorated by systemic blockade of the CCR2, if given for 4wks total within the first 8wks after DMM. However, if treatment was maintained for 8wks or more it was less effective on subsequent structural progression while still inhibiting pain, suggesting a disconnect between structure and pain that has been noted in human OA. These data suggest that CCR2 signaling has cellular and stage specific roles in OA, with beneficial effects when targeted at early stages. We hypothesize that injury-induced alterations in joint mechanics upregulate the CCR2 pathway in cartilage and bone in a time- dependent manner altering the structural organization of both tissues, ultimately leading to OA and pain. We propose to determine the role of dysregulated CCR2 signaling in cartilage at sequential times during injury- and age-induced OA, in order to establish the contribution of this tissue to the whole joint degeneration and OA pain (Aim 1). We will also evaluate whether osteoblast expression of CCR2 contributes to joint damage and pain during injury-induced OA (Aim 2). To accomplish this, we will obtain an inducible tissue-specific CCR2 deletion in chondrocytes (Aim 1) and osteoblasts (Aim 2) by combining chondrocyte- or osteoblast-specific expression of CreER with Tam injections in CCR2flox/flox mice crossed with Aggrecan-CreERT2 or Col1α1CreER, respectively. Because the myeloid infiltration consisting of macrophages and osteoclasts may cause accelerated OA bone remodeling that may reflect on bone damage and, indirectly, on cartilage homeostasis, we will also conditionally inactivate CCR2 in macropahges/osteoclasts (Aim 3) by crossing CCR2flox/flox mice with LysMERCre. We will also evaluate potential pathways altered by each tissue-selective CCR2 deletions. In addition, by using in-vitro human primary chondrocyte cultures, we will study the signaling pathways by which activation of CCR2 with its multiple ligands stimulates MMP production.