15-LOX-1 as a druggable target in the acute to chronic pain transition of rheumatoid arthritis

项目摘要 类风湿性关节炎（Rheumatoid arthritis，RA）是最常见的自身免疫性疾病之一，发病率约为0.5-1%。 目前的治疗包括类固醇、生物制剂和非甾体抗炎药（NSAID）靶向 环氧合酶（考克斯）减轻炎症的临床体征;然而，以机械性疼痛为特征的关节疼痛， 超敏反应（异常性疼痛）和功能障碍（握力不足，运动抑制），沿着 精神病合并症（焦虑、抑郁）常常远远超过外周炎症的消退。 因此，迫切需要用于管理持续性关节炎疼痛的新疗法。在 在RA的K/BxN血清转移模型中，通过常规方法减轻早期炎症阶段的异常性疼痛。 治疗剂（NSAID、抗癫痫药加巴喷丁、TNF α受体抗体依那西普、部分μ阿片类药物） 受体激动剂丁丙诺啡），但加巴喷丁仅在晚期炎症后 阶段，表明这些药物靶向的途径可能不会驱动关节炎疼痛的慢性化。 向神经性炎症后异常性疼痛的转变由脊髓Toll样受体4（TLR 4）介导， 鞘内（IT）递送TLR 4激动剂脂多糖（LPS）以模拟该过渡期产生 触觉异常性疼痛和握力缺陷（一种广泛使用的肌肉骨骼功能流变学测量方法） 在两性中。脂氧合酶15-LOX-1已成为疾病模型中的可行靶点，其生物活性 代谢物（12/15-脂氧合酶代谢物; 12/15-LM）在脊髓水平上促成异常性疼痛。我们 已发表的和初步的数据表明脊髓12/15-LM在机械性疼痛超敏反应中的关键作用 在啮齿类动物中：i）12/15-LM激活伤害感受器中表达的多个靶标; ii）鞘内（IT）LPS（TLR 4激动剂） 在啮齿动物中产生异常性疼痛并增加15-LOX-1表达; iii）15-LOX-1的脊髓或全身抑制， 而不是考克斯，消除大鼠和小鼠中TLR 4介导的异常性疼痛，和iv）大鼠中的外周炎症， 小鼠的K/BxN血清转移关节炎通过几种受体诱导12/15-LM的脊髓合成和异常性疼痛。 考虑到这些观察结果，本文提出的研究将检验脊柱15-LOX 在男性和女性K/BxN关节炎期间，激活通过3 目的是通过研究1）脊髓15-LOX-1在K/BxN关节炎疼痛急性向慢性转变中的作用2） 脊髓15-LOX-1的细胞来源和3）脊髓受体介导的15-LOX-1的伤害感受作用 代谢物使用各种行为（触觉，握力，开放领域，炎症的临床体征）， 分子和生物化学分析。总体而言，预期成果将解决以下方面的重大差距： 了解慢性疼痛的感觉和情感成分的机制， 15-LOX-1作为一种新的药物靶点，以阻止多种下游受体的激活， 治疗炎症消退后持续存在的关节炎疼痛状态的治疗策略。

PROJECT SUMMARY Rheumatoid arthritis (RA) is one of the most common autoimmune diseases with a 0.5-1% worldwide incidence. Current therapies including steroids, biologics and nonsteroidal anti-inflammatory drugs (NSAIDs) targeting cyclooxygenases (COX) alleviate clinical signs of inflammation; however, joint pain characterized by mechanical hypersensitivity (allodynia) and functional disabilities (grip strength deficit, locomotor depression) along with psychiatric comorbidities (anxiety, depression) often remain well beyond resolution of peripheral inflammation. Thus, there exists a critical need for new therapeutics for the management of persistent arthritic pain. In the K/BxN serum transfer model of RA, allodynia during the early inflammatory phase is attenuated by conventional therapeutics (NSAIDs, the antiepileptic gabapentin, the TNFa receptor antibody etanercept, the partial mu opioid receptor agonist buprenorphine), but is only modestly reduced by gabapentin in the late post-inflammatory phase, indicating that the pathways targeted by these agents likely do not drive the chronification of arthritic pain. Transition to the neuropathic post-inflammatory allodynia is mediated by spinal Toll-like receptor 4 (TLR4), and intrathecal (IT) delivery of the TLR4 agonist Lipopolysaccharide (LPS) to model this transition phase produces tactile allodynia and grip strength deficits (a widely utilized rheumatological measure of musculoskeletal function) in both sexes. The lipoxygenase 15-LOX-1 has emerged as a viable target in disease models, and its bioactive metabolites (12/15-lipoxygenase metabolites; 12/15-LMs) contribute to allodynia at the spinal level. Our published and preliminary data demonstrate a critical role of spinal 12/15-LMs in mechanical pain hypersensitivity in rodents: i) 12/15-LMs activate multiple targets expressed in nociceptors; ii) intrathecal (IT) LPS (TLR4 agonist) produces allodynia in rodents and increases 15-LOX-1 expression; iii) spinal or systemic inhibition of 15-LOX-1, but not of COX, abrogates TLR4-mediated allodynia in rats and mice and iv) peripheral inflammation in rats or K/BxN serum transfer arthritis in mice induces spinal synthesis of 12/15-LMs and allodynia via several receptors. Given these observations, the proposed studies herein will test the overarching hypothesis that spinal 15-LOX activation mediates the transition from acute to chronic pain during K/BxN arthritis in males and females via 3 aims by investigating 1) the role of spinal 15-LOX-1 in the acute to chronic transition of pain in K/BxN arthritis 2) the cellular source(s) of spinal 15-LOX-1 and 3) the spinal receptor-mediated nociceptive effects of 15-LOX-1 metabolites using a variety of behavioral (tactile, grip strength, open field, clinical signs of inflammation), molecular and biochemical assays. Collectively, the expected results will address significant gaps in understanding of the mechanisms underlying sensory and affective components of chronic pain and interrogate 15-LOX-1 as a novel druggable target to impede activation of multiple downstream receptors in an alternative therapeutic strategy for treating arthritic pain states persisting after resolution of inflammation.