脊髓Fc-gamma RⅠ 在神经病理性疼痛大鼠中的作用及机制研究

Neuropathic pain is a devastating neurological disease that seriously affects the quality of life in patients. Despite a high level of incidence, the underlying mechanisms of neuropathic pain are still poorly understood. The nervous system has long been regarded as "immunological privileged site". But this concept has being challenged by increasing experimental evidences with progresses in neuroscience. Recently, accumulating evidence has shown that several immunological molecules previously thought to be exclusively expressed by immune cells are also produced by nervous cells. Such molecules are thought to participate in the cross-talk between the immune and the nervous systems. Immunoglobulin G, an important immunological molecule, was traditionally thought to be produced by B lymphocytes only. Recent studies have demonstrated that immunoglobulin G and its receptors (Fc-gamma receptors) expressed in the hippocampus, spinal cord and dorsal root ganglion. However, the functions are still unknown. The clinical data suggest that treatment with intravenous immunoglobulin reduce pain in the chronic pain patients. Therefore, the distribution of immunoglobulin G and Fc-gamma receptors in the spinal cord may be involved in the mechanism of neuropathic pain. The present thesis is to examine the role of Fc-gamma receptor Ⅰin the nervous system on the model of neuropathic pain. The project is planned to observe the expression of immunoglobulin G and Fc-gamma receptorⅠ involved in the occurrence of neuropathic pain in the central nervous systems, using immunofluorescence histochemistry, western blot and real time PCR methods; and to examine the underlying mechanism using behavioral tests, the primary cell culture, PI，TUNEL and so on. And the mechanism may be related with the cell apoptosis. These studies will supplement the mechanisms of neuropathic pain, and provide more experimental and theoretical data for the clinical application of immunoglobulin.

神经病理性疼痛是疼痛发生和治疗研究的重要领域。神经免疫是最近研究的热点，课题组前期发现原本属于免疫隔离区的脊髓组织中有免疫球蛋白G（IgG）受体（FcγRⅠ）的分布和表达，但其功能尚不清楚。近期临床研究报道静脉注射免疫球蛋白对慢性疼痛的病人具有良好的治疗效果。因此推测与疼痛密切相关的脊髓中分布的FcγRⅠ可能参与神经病理性疼痛的发生。本项目拟采用行为学，免疫荧光组织化学，Western blot以及Real time PCR等方法，观察分布于脊髓的FcγRⅠ是否参与神经病理性疼痛的发生，影响疼痛相关物质TNF-α，P物质，CGRP和TRVP的表达；运用原代细胞培养，PI，TUNEL等方法观察其机制是否与细胞凋亡有关，补充神经病理性疼痛的发生机制，为免疫球蛋白的临床应用提供更有利的实验基础。

神经病理性疼痛是指原发或继发与神经系统损害或功能障碍所导致的疼痛，表现为痛阈下降，痛反应增强、痛觉过敏和自发性疼痛，给患者带来极大的痛苦，缺乏有效的治疗手段，因此探索神经病理性疼痛的发病机制以及寻找安全有效的治疗方法成为最重要的研究方向。课题组发现原本属于免疫隔离区的脊髓组织中有了免疫球蛋白G（IgG）受体（FcγRⅠ）的分布和表达，免疫受体FcγRⅠ是否参与疼痛的发生及机制如何尚不清楚。本课题通过建立神经病理性疼痛模型，模型给予FcγRⅠ抗体，正常大鼠给予IgG免疫复合物，以及神经病理性疼痛大鼠注射免疫球蛋白四种不同模式进行实验研究，结果发现神经慢性压迫性损伤引起大鼠机械性和热辐射痛觉过敏，给予FcγRⅠ抗体能够缓解两种痛觉过敏；正常大鼠注射IgG免疫复合物也能引起大鼠两种痛觉过敏；静脉注射免疫球蛋白能够缓解神经病理性疼痛大鼠痛觉过敏。同时，分别检测了FcγRⅠ的蛋白质和mRNA水平的表达情况，其水平的高低与疼痛程度有一定的相关性，综合以上结果提出FcγRⅠ参与大鼠神经病理性疼痛的发生。其作用机制如何？通过在体实验和离体细胞实验，研究发现FcγRⅠ通过调控C3,CGRP，TNF-α,IL-1β以及P物质等疼痛相关物质的表达来参与疼痛发生，以及大鼠脊髓中FcγRⅠ介导的疼痛与诱导细胞凋亡相关。因此本课题提出大鼠脊髓中FcγRⅠ参与神经病理性疼痛的发生，其机制与细胞凋亡相关，通过调控C3,CGRP，TNF-α,IL-1β以及P物质等疼痛相关物质的表达参与神经病理性疼痛的发生和发展。.在本课题中脊髓组织中神经元表达的免疫受体FcγRⅠ参与了神经病理性疼痛的发生，提出了神经病理性疼痛发生的神经免疫机制，发现了在神经病理性疼痛机制中神经系统与免疫系统之间的相互作用，提出了一种较新颖的神经病理性疼痛的发病机制，同时提出了治疗神经病理性疼痛的新靶点，为新药的开发提供了新的思路，也为免疫球蛋白的临床推广应用提供更有利的实验基础。