Sensory Cross-Activation in Bowel Dysfunction

项目摘要 在人类中，疼痛在远离患者的位置被感知是常见的 器官.肠功能障碍也是如此。炎症性肠病（IBD）和/或易激惹患者 肠综合征（IBS）经常经历膀胱过度活动和躯体疼痛。了解外围设备 疼痛产生和感觉交叉敏感的机制有助于治疗方法的发展 以最小的中枢副作用治疗疼痛合并症。周围神经胶质细胞正在增加 认识到它们在调节感觉神经元活动中的作用。背根卫星胶质细胞 神经节（DRG）位于感觉神经元周围，并通过SGC网络连接感觉神经元。使用 我们通过clozapine-N-oxide（CNO）激活神经胶质细胞，发现cro激活hM 3Dq， 神经胶质细胞导致降钙素基因相关肽（CGRP）向脊髓的释放增强，这是一种必需的免疫调节因子。 脊髓中枢敏感化过程。神经胶质细胞的活化也促进结肠的超敏反应， 膀胱和后爪。在DRG中，TrkB. T1由SGCs而不是神经元表达。钙（Ca 2+） 活性是SGCs中由hM 3Dq和TrkB.T1介导的共同途径。重要的是，使用独特的SGC- 感觉神经元共培养系统中，我们发现TrkB.T1介导的SGCs的激活导致 参与疼痛处理的相邻感觉神经元。因此，我们假设TrkB.T1介导 神经胶质-神经元相互作用，并参与感觉神经元交叉激活和跨器官敏化。到 为了验证这一假设，我们将使用外周血中具有可诱导条件性TrkB.T1缺失（TrkB.T1cKO）的小鼠， 胶质细胞主要来源于SGCs，小鼠外周胶质细胞表达hM 3Dq或hM 4Di。我们将执行分子 和功能分析结肠膀胱感觉神经元交叉激活和跨器官敏化在这些 独特的鼠标线（目标1）。TrkB.T1在SGCs中的功能作用是增加Ca 2+水平， 促进胶质递质释放。我们已经鉴定了许多受TrkB.T1调节的神经胶质介质 通过蛋白质组学筛选和转录分析，我们将表征TrkB.T1介导的 神经胶质传递和神经胶质传递素促进的跨器官感觉神经元激活 致敏（目标2）。中枢致敏不仅有助于结肠-膀胱交叉致敏， 是内脏-躯体交叉致敏的基础因此，我们将研究TrkB.T1介导的SGC-790是否是一种新的细胞因子。 感觉神经元串扰有助于CGRP中枢释放并导致内脏-躯体交叉致敏 (Aim 3）。在这三个目标中，我们将使用多种动物模型，并在体内和体外应用 功能和机制研究的方法。有趣的是，我们的初步数据显示TrkB.T1是 两性异形因此，我们将在两种性别中进行实验。我们预计将揭示 TrkB.T1在神经胶质细胞-神经元相互作用中的作用，为理解跨器官的发展提供见解。 致敏并提出治疗靶点。

PROJECT SUMMARY It is a common occurrence in human that pain is perceived at a remote location away from the diseased organ. This is also true with bowel dysfunction. Patients with inflammatory bowel diseases (IBD) and/or irritable bowel syndrome (IBS) often experience bladder hyperactivity and somatic pain. Understanding the peripheral mechanisms of pain generation and sensory cross-sensitization helps development of therapeutic approaches with minimum central adverse effects to treat pain comorbidity. Peripheral glial cells are gaining increased recognition for their roles in modulating sensory neuron activity. Satellite glial cells (SGCs) of dorsal root ganglia (DRG) reside around sensory neurons and connect sensory neurons through SGC networks. Using Cre-based expression of hM3Dq to activate glial cells by clozapine-N-oxide (CNO), we show that activation of glial cells leads to an enhanced calcitonin gene-related peptide (CGRP) release to the spinal cord, an essential process in spinal central sensitization. Activation of glial cells also facilitates hypersensitivity of the colon, urinary bladder and hind paw in mice. In DRG, TrkB.T1 is expressed by SGCs but not neurons. Calcium (Ca2+) activity is a common pathway mediated by hM3Dq and TrkB.T1 in SGCs. Importantly, using a unique SGC- sensory neuron co-culture system we show that activation of SGCs mediated by TrkB.T1 leads to activation of adjacent sensory neurons that participate in pain processing. We therefore hypothesize that TrkB.T1 mediates glia-neuron interaction and participates in sensory neuron cross-activation and cross-organ sensitization. To test this hypothesis, we will use mice with inducible conditional TrkB.T1 deletion (TrkB.T1cKO) from peripheral glia mainly from SGCs and mice with hM3Dq or hM4Di expression in peripheral glia. We will perform molecular and functional analysis of colon-bladder sensory neuron cross-activation and cross-organ sensitization in these unique mouse lines (Aim 1). The functional roles of TrkB.T1 in SGCs are to increase the levels of Ca2+ to promote gliotransmitter release. We have identified a number of glial mediators that are regulated by TrkB.T1 in SGCs through proteomic screening and transcriptional analysis. We will characterize TrkB.T1-mediated gliotransmission and gliotransmitter-facilitated sensory neuron activation in the context of cross-organ sensitization (Aim 2). Central sensitization not only contributes to colon-bladder cross-sensitization but also underlies viscero-somatic cross-sensitization. We therefore will examine whether TrkB.T1-mediated SGC- sensory neuron crosstalk contributes to CGRP central release and leads to viscero-somatic cross-sensitization (Aim 3). Throughout the three aims, we will use more than one animal models and apply in vivo and in vitro approaches for functional and mechanistic studies. Interestingly, our preliminary data show that TrkB.T1 is sexually dimorphic. We therefore will perform our experiments in both genders. We anticipate revealing the role of TrkB.T1 in glia-neuron interaction to provide insights in understanding the development of cross-organ sensitization and suggest therapeutic targets.