Analysis of Neuro-Epidermal Interactions

描述（由申请人提供）：角化细胞和表皮神经纤维的相互作用已成为感觉传导和疼痛的重要界面，可能是疼痛性周围神经病变机制的一个因素。角质形成细胞表达受体和通道，使它们能够“感知”机械和热刺激，并通过释放信使分子将信号传递给表皮神经纤维。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，感觉神经元中含有的神经肽具有调节角化细胞的能力，包括它们的细胞因子和生长因子的产生和分泌。部分周围神经损伤导致神经性疼痛与受损神经纤维变性和邻近未受损神经纤维功能改变有关。表皮神经支配改变对动态神经-角化细胞关系的影响尚不清楚。本R21提案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。特异性目标1将解决神经损伤引起的神经支配变化将改变角质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将与角化细胞表达的受体和通道有关，这些受体和通道涉及感觉转导以及已知的使感觉神经元敏感的细胞因子。表皮的功能变化将根据角质细胞ATP释放的测量来评估。特异性目标2将确定感觉神经元对器官型培养中角质形成细胞蛋白表达和功能的影响，其中神经元输入将通过与感觉神经元共培养引入。这些实验将解决一个假设，即选择的感觉神经元子集将对角质形成细胞有不同的影响。生化方法将用于确定候选介质的神经角质细胞信号。神经损伤后动态神经-角化细胞关系的变化可能通过存活的表皮神经纤维的致敏和角化细胞对感觉刺激的转导的改变而促进神经性疼痛机制。因此，神经-角化细胞的相互作用和神经损伤对它们的调节是神经损伤病理生物学后果中一个以前未被探索的组成部分，对它们的理解可能会导致发现神经性疼痛的新的外周治疗靶点。公共卫生相关性：拟议的项目将分析感觉信息传递中两个重要结构：感觉神经和皮肤表皮之间的相互作用。这些研究将确定与神经损伤相关的角化细胞变化模式，为深入分析神经-角化细胞相互作用对疼痛的贡献提供基础。操纵这些相互作用可能能够提供一种外周受限的治疗策略。

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.