Analysis of Neuro-Epidermal Interactions

描述(申请人提供)：角质形成细胞和表皮神经纤维的相互作用已成为感觉转导和疼痛的重要界面，并可能是导致痛性周围神经病的机制的一个因素。角质形成细胞表达受体和通道，使它们能够“感觉”机械和热刺激，并通过信使分子的释放将信号传递到表皮神经纤维。角质形成细胞分泌的生长因子和细胞因子也可能影响支配表皮的感觉神经元的长期变化。相反，感觉神经元中包含的神经肽具有调节角质形成细胞的能力，包括它们产生和分泌细胞因子和生长因子。导致神经病理性疼痛的周围神经部分损伤与受损神经纤维的变性和邻近未损伤神经纤维的功能改变有关。改变的表皮神经支配对动态的神经-角质形成细胞关系的影响尚不清楚。R21建议的目的是确定表皮神经支配对角质形成细胞蛋白表达和功能的影响。具体目标1将阐述神经损伤引起的神经支配变化将改变角质形成细胞蛋白表达和功能的假设。表皮神经支配和神经损伤诱导的超敏反应与角质形成细胞表达与感觉转导有关的受体和通道，以及已知的使感觉神经元敏感的细胞因子有关。表皮的功能变化将基于角质形成细胞三磷酸腺苷释放的测量来评估。具体目标2将确定感觉神经元在器官培养中对角质形成细胞蛋白表达和功能的影响，在器官培养中，将通过与感觉神经元的共同培养引入神经元输入。这些实验将解决这样的假设，即选定的感觉神经元亚群将对角质形成细胞产生不同的影响。生化方法将用于确定神经角质形成细胞信号的候选介体。神经损伤后神经-角质形成细胞动态关系的改变可能通过对存活的表皮神经纤维的敏化和角质形成细胞对感觉刺激转导的改变而参与神经病理性疼痛机制。因此，神经-角质形成细胞的相互作用及其在神经损伤中的调节作用代表了神经损伤的病理生物学后果中一个以前未被探索的组成部分，它们的理解可能导致识别神经病理性疼痛的新的外周治疗靶点。与公共健康相关：拟议的项目将分析感官信息传递中的两个重要结构之间的相互作用：感觉神经和皮肤的表皮。这些研究将确定与神经损伤相关的角质形成细胞的变化模式，这将为深入分析神经-角质形成细胞相互作用对疼痛的贡献提供基础。对这些相互作用的操纵可能能够提供一种外围受限的治疗策略。

Description (provided by applicant): The interaction of keratinocytes and epidermal nerve fibers has emerged as an important interface in sensory transduction and pain and may be a factor in the mechanisms underlying painful peripheral neuropathies. Keratinocytes express receptors and channels that enable them to "sense" mechanical and thermal stimuli and transmit signals to epidermal nerve fibers through the release of messenger molecules. Growth factors and cytokines secreted from keratinocytes are also likely to impact long-term changes within the sensory neurons that innervate epidermis. Conversely, neuropeptides contained within sensory neurons have the ability to modulate keratinocytes, including their production and secretion of cytokines and growth factors. Partial peripheral nerve injury that leads to neuropathic pain is associated with degeneration of injured nerve fibers and altered function of adjacent uninjured fibers. The impact of altered epidermal innervation on the dynamic neuro-keratinocyte relationship is unknown. The objective of this R21 proposal is to determine the effects of epidermal innervation on keratinocyte protein expression and function. Specific Aim 1 will address the hypothesis that nerve injury-induced changes in innervation will alter keratinocyte protein expression and function. Epidermal innervation and nerve injury- induced hypersensitivity will be correlated with keratinocyte expression of receptors and channels implicated in sensory transduction as well as cytokines known to sensitize sensory neurons. Functional changes in epidermis will be evaluated based on measurement of keratinocyte ATP release. Specific Aim 2 will determine the effects of sensory neurons on protein expression and function of keratinocytes in organotypic culture where neuronal input will be introduced by co-culture with sensory neurons. These experiments will address the hypothesis that selected subsets of sensory neurons will have differential effects on keratinocytes. Biochemical approaches will be used to identify candidate mediators of neuro-keratinocyte signaling. Changes in the dynamic neuro-keratinocyte relationship following nerve injury may contribute to neuropathic pain mechanisms through sensitization of surviving epidermal nerve fibers and changes in keratinocyte transduction of sensory stimuli. Therefore, neuro-keratinocyte interactions and their modulation by nerve injury represent a previously unexplored component of the pathobiological consequences of nerve injury, and their understanding may lead to identification of novel peripheral therapeutic targets for neuropathic pain. PUBLIC HEALTH RELEVANCE: The proposed project will analyze the interaction between two important structures in the transmission of sensory information: sensory nerves and the epidermis of the skin. These studies will identify a pattern of keratinocyte changes associated with nerve injury that will provide a foundation for in-depth analysis of the contribution of neuro-keratinocyte interactions to pain. Manipulation of these interactions may be able to provide a peripherally restricted therapeutic strategy.