Role of CCR7 in Clinical Response in Inflammatory Arthritis

描述（由申请人提供）：类风湿性关节炎（RA）是一种慢性炎症性疾病，可导致多种细胞（包括巨噬细胞）介导的关节破坏。虽然在治疗方面取得了很大进展，但对有效治疗的作用机制知之甚少。然而，已发表的研究证明，滑膜组织中巨噬细胞浸润的程度是临床结果的强有力预测因素。此外，治疗前后的滑膜组织活检检查表明，无论治疗如何，下层CD 68+巨噬细胞的减少与DAS 28的减少密切相关。有效治疗后滑膜组织巨噬细胞减少的机制尚不清楚。潜在的机制包括单核细胞向组织中的募集减少，细胞死亡增加，如凋亡，或通过淋巴管向淋巴结的运输增加。了解负责任的机制是至关重要的，以确定更安全，合理设计，更有效的治疗，特别是对那些没有充分响应目前可用的治疗。在开始英夫利西单抗治疗后1、24和48小时检查滑膜组织凋亡的研究， 导致滑膜组织巨噬细胞的显著减少，未能使用金标准电子显微镜证实细胞凋亡。此外，采用直接追踪循环单核细胞迁移至RA滑膜组织的技术，在阿达木单抗治疗患者中未观察到单核细胞迁移减少，阿达木单抗治疗导致滑膜组织巨噬细胞快速减少。总之，这些观察结果表明，巨噬细胞凋亡或单核细胞迁移到RA关节的减少都不是对TNF抑制剂的临床反应的原因，这表明巨噬细胞和可能的其他细胞类型从RA关节中流出增加作为重要作用机制的潜在作用。 我们的初步数据表明，CCR 7是由RA滑膜组织巨噬细胞表达。我们最近还发现，CCR 7配体CCL 19和CCL 21在RA滑膜组织中表达。此外，CCR 7、CCL 19和CCL 21由包括TNF α的炎症介质诱导。在患有动脉粥样硬化的小鼠中的研究表明，巨噬细胞从患病动脉的排出是由CCR 7介导的。此外，CCR 7缺陷型小鼠表现出更多的慢性免疫复合物介导的关节炎，并且滑膜炎高度富集于巨噬细胞。因此，我们建议采用小鼠关节炎模型来检验有效治疗的机制是由CCR 7介导的增加巨噬细胞从组织中排出的假设。将采用两个特定目的来检验该假设：（1）使用人TNF转基因小鼠，确定对TNF抑制剂或TNF加IL-1的治疗的应答是否将通过CCL 19和CCL 21的中和而被阻止。(2)使用人TNF转基因小鼠，确定对TNF或TNF加IL-1的抑制的应答是否由CCR 7介导。

DESCRIPTION (provided by applicant): Rheumatoid arthritis (RA) is a chronic inflammatory disease that may result in joint destruction mediated by a variety of cells including macrophages. While great advances in therapy have been made, the mechanism of action of effective therapy is poorly understood. However, published studies document that the extent of macrophage infiltration in the synovial tissue is a strong predictor of clinical outcome. Further, examination of synovial tissue biopsies before and after therapy, demonstrate that the reduction of sublining CD68+ macrophages strongly correlates with the reduction of the DAS28, regardless of the therapy. The mechanism by which synovial tissue macrophages are reduced following effective therapy is not known. Potential mechanisms include reduced recruitment of monocytes into the tissue, increased cell death, such as apoptosis, or increased trafficking out of the tissue via the lymphatics to the lymph nodes. An understanding of the responsible mechanism is critical to identify safer, rationally designed, more effective therapy, especially fo those who do not respond adequately to currently available therapy. Studies that examined synovial tissue apoptosis 1, 24 and 48 hours after the initiation of therapy with infliximab, which resulted in significant reduction of synovial tissue macrophages, failed to demonstrate apoptosis employing the gold standard, electron microscopy. Further, employing a technique to directly track the migration of circulating monocytes into RA synovial tissue, no reduction of monocyte migration was observed in patients treated with adalimumab, a therapy that results in rapid reduction of synovial tissue macrophages. Together these observations suggest than neither macrophage apoptosis nor reduction of migration of monocytes into the RA joint is responsible for the clinical response to TNF inhibitors, suggesting a potential role for increased egress of macrophages, and possibly other cell types, from the RA joint as an important mechanism of action. Our preliminary data demonstrate that CCR7 is expressed by RA synovial tissue macrophages. Also we have shown recently that the CCR7 ligands CCL19 and CCL21 are expressed in RA synovial tissue. Further, CCR7, CCL19 and 21 are induced by inflammatory mediators including TNFalpha. Studies in mice with atherosclerosis demonstrate that egress of macrophages from diseased aortas is mediated by CCR7. Additionally, CCR7 deficient mice demonstrate more chronic immune complex mediated arthritis, and the synovitis is highly enriched in macrophages. Therefore, we propose to employ a murine model of arthritis to examine the hypothesis that the mechanism of effective therapy is increased macrophage egress from tissue which is mediated by CCR7. This hypothesis will be tested employing two specific aims: (1) Employing human TNF transgenic mice, determine if the response to treatment with inhibitors of TNF or TNF plus IL-1 will be prevented by the neutralization of CCL19 and CCL21. (2) Employing human TNF transgenic mice, determine if the response to inhibition of TNF or TNF plus IL-1 is mediated by CCR7.