Role of Infiltrating CD4+ T Lympoocytes in Neuropathic Pain

描述（由申请人提供）：描述：尽管有许多研究描述了神经免疫应答在神经性疼痛中的作用，但适应性免疫在神经性疼痛中的作用仍是一个研究不足的领域。无胸腺大鼠（缺乏成熟的T淋巴细胞）和MHC II基因敲除（KO）小鼠（CD 4 + T淋巴细胞数量减少）在神经损伤后出现显著降低的机械性异常性疼痛，这一事实突出了T淋巴细胞在神经性疼痛中的重要作用。本研究将描述神经损伤后中枢神经系统（CNS）浸润T淋巴细胞的特征，并提供它们在CNS中双向相互作用的机制，从而建立一个研究神经病理性疼痛中可能的适应性免疫反应相关治疗靶点（如CD 40-CD 40 L阻断）的模型系统。将使用成熟的神经性疼痛啮齿动物模型，L5脊神经横断（L5 Tx），并通过触觉敏感性反应（人类机械超敏反应的代表）测量小鼠的疼痛行为。我们假设神经损伤激活的CD 4 + T淋巴细胞浸润到脊髓的受影响区域，并通过细胞表面CD 40-CD 40 L接合与小胶质细胞（单核细胞来源的CNS驻留细胞）相互作用，进一步促进小胶质细胞产生促炎细胞因子，这些因子在维持长期疼痛行为中很重要。本研究将按照3个具体目标开展：确定1）L5 Tx后腰椎脊髓中小胶质细胞CD 40表达和浸润性CD 4 + T淋巴细胞CD 40 L表达之间的时间和空间关系，2）通过使用CD 4KO小鼠，小胶质细胞CD 40-CD 4 + T淋巴细胞CD 40 L连接在L5 Tx诱导的机械超敏反应中的参与，涉及CD 40 KO小鼠的骨髓嵌合体和CD 40阻断抗体，和3）L5 Tx后CNS CD 40-CD 40 L相互作用诱导的小胶质细胞促炎细胞因子产生。公共卫生相关性：神经性疼痛，定义为由神经系统中的原发性病变或功能障碍引发或引起的疼痛，是最具破坏性的慢性疼痛之一，也是与HIV感染相关的常见神经系统并发症，在美国每年影响3-5百万人。然而，它在很大程度上仍然没有得到最佳处理。这项研究将进一步探讨适应性免疫在神经病理性疼痛的病理生理学中的作用，并可能为新的非成瘾性治疗提供思路。

DESCRIPTION (provided by applicant): Description: Despite there being numerous studies delineating the role of neuroimmue responses in neuropathic pain, the role of adaptive immunity in neuropathic pain is yet an under-studied area. The fact that athymic rats (that lack mature T lymphocytes) and MHC II knockout (KO) mice (who have decreased numbers of CD4+ T lymphocytes) developed significantly reduced mechanical allodynia following nerve injury highlight the significant role of T lymphocytes in neuropathic pain. This proposal will characterize the central nervous system (CNS) infiltrating T lymphocytes after nerve injury and provide a mechanism for their bi-directional interactions in the CNS, thus establishing a model system for investigating possible adaptive immune response-related therapeutic targets (such as CD40-CD40L blockade) in neuropathic pain. A well-established rodent model of neuropathic pain, L5 spinal nerve transection (L5Tx), will be used and pain behavior in mice will be measured by the tactile sensitivity response, a representation of mechanical hypersensitivity in humans. We hypothesize that nerve injury activated CD4+ T lymphocytes infiltrate into the affected region of the spinal cord and interact with microglia (the CNS resident cells of monocyte origin) via cell surface CD40-CD40L engagement, further promoting microglial production of proinflammatory cytokines, factors important in maintaining long-lasting pain behavior. This study will be carried out following 3 specific aims: Determine 1) the temporal and spatial relationships between microglial expression of CD40 and infiltrating CD4+ T lymphocyte expression of CD40L in the lumbar spinal cord post-L5Tx, 2) the involvement of the microglial CD40-CD4+ T lymphocyte CD40L ligation in L5Tx-induced mechanical hypersensitivity by using CD4KO mice, bone marrow chimeras involving CD40KO mice, and a CD40 blocking antibody, and 3) the microglial proinflammatory cytokine production induced by the CNS CD40-CD40L interaction post-L5Tx. Public Health Relevance: Neuropathic pain, defined as pain initiated or caused by a primary lesion or dysfunction in the nervous system, is one of the most devastating kinds of chronic pain, and a common neurological complication associated with HIV infection, affecting 3-5 million people every year in the US. However, it is still largely treated sub-optimally. This study will further investigate the role of adaptive immunity in the pathophysiology of neuropathic pain and may yield ideas for new non-addictive treatments.