A Novel Mechanism of Mast Cell-Nerve Interactions in the Esophagus

食管肥大细胞与神经相互作用的新机制

基本信息

批准号：
10266097
负责人：
Xinzhong Dong
金额：
$ 53.08万
依托单位：
JOHNS HOPKINS UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2020
资助国家：
美国
起止时间：
2020-09-21 至 2023-08-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/10266097
关键词：
Acids Acute Address Allergens Allergic Attenuated Biopsy Specimen C Fiber Cations Chronic Connective Tissue Cytoplasmic Granules Data Defensins Disease Eosinophil Granule Proteins Eosinophil cationic protein Eosinophilic Esophagitis Epithelial Esophageal Diseases Esophagitis Esophagus Functional disorder Funding G-Protein-Coupled Receptors Gastroesophageal reflux disease Genome Heartburn Histology Human IgE Image Immunologics Inflammation Inflammatory Interleukin-5 Intestinal Mucosa Investigation Knowledge Lamina Propria Lead Location Mediating Mediator of activation protein Methodology Modeling Mucous Membrane Mus Nerve Neuroimmune Neurons Neuropeptides Nociception Pain Pathogenesis Peptic Esophagitis Permeability Phenotype Play Proteins Publishing Reaction Reflux Refractory Role Specimen Stratified Squamous Epithelium Substance P Symptoms Techniques Tryptase Wild Type Mouse cytokine eosinophil experimental study extracellular immune activation mRNA Expression mast cell mouse model new therapeutic target novel receptor recruit response tissue injury two-photon

项目摘要

Project Summary Marked increases in esophageal mast cells (MCs) have been identified not only in allergic but also in non-allergic esophageal disorders. At present, their roles in the pathogenesis of those disorders are still less clear. Unlike intestinal mucosal MCs, esophageal MCs are predominantly distributed in the lamina propria of the mucosa, whereas they are matured in non-keratinized stratified squamous epithelium and developed into distinctive phenotype. Recently, the Immunologic Genome (ImmGen) Project Consortium has classified esophageal MC as one of the typical connective tissue MCs. Moreover, our new study has identified that MrgprB2 (the orthologue of human MrgprX2) is a GPCR and exclusively expressed in connective tissue MCs. Many basic secretagogues (substance P, VIP, PAMP, defensins, et al) and eosinophil cationic proteins are now known to activate mast cells exclusively via MrgprB2/X2 mechanisms. Our published and preliminary studies are supporting the novel hypothesis that MrgprB2 (MrgprX2 in human) mediates esophageal inflammation-induced MC activation and directly contributes to esophageal epithelial barrier dysfunction and esophageal afferent nociceptive nerve hyperexcitability. We will address this hypothesis in the mouse and human esophagus with following aims. In Aim 1, we will characterize MrgprB2-positive MCs in healthy and inflamed esophagus with respects to their distribution, phenotype, and activation response (mediators/cytokines release) to basic secrectagogues. We will then address the hypothesis that MrgprB2 mediates non-IgE-dependent MC activation by comparing MC mediator release in inflamed esophagus in wild type and MrgprB2mut mice. Lastly, we will explore, in an eosinophilic esophagitis model, whether eosinophil granule basic proteins (MBP, EPO, END,) directly activate MrgprB2. In Aim 2, we will continue to advance our interesting preliminary data demonstrating that reflux-induced esophageal epithelial barrier dysfunction (increased permeability) is significantly attenuated in MrgprB2 mut mice. To determine if non-MrgprB2 mast cell activation mechanisms also contribute to barrier breakdown we will compare permeability changes in our reflux vs allergic esophagitis models in three groups of mice, wild type mice; mice where the mast cells do not express functional MrgprB2 mut; and thirdly mice that are mast cell deficient. In Aim 3, we will compare the effect of MrgprB2 vs allergen-evoked mast cell activation on esophageal nociceptive C-fiber terminal activities using our well-established extra-cellular recording techniques along with our newly-developed two-photon neuron imaging methodology. In Aim 4, we will compare the expression and function of MrgprX2 in human esophageal biopsy specimens from reflux and eosinophilic esophagitis and then determine their correlations with esophageal histology/symptoms. Translationally, we will briefly characterize MrgprX2 expression and function in mouse esophagus by using our newly-established humanized MrgprX2 mouse line. Clarifying MrgprB2/X2-mediated esophageal mast cell activation may motivate investigation of novel targeted therapeutic strategies for esophageal inflammatory disorders.

项目概要不仅在过敏性食管疾病中，而且在非过敏性食管疾病中，食管肥大细胞（MC）显着增加。目前，它们在这些疾病发病机制中的作用仍不清楚。与肠粘膜MC不同，食管MC主要分布在粘膜固有层，而它们在非角化的复层鳞状上皮中成熟并发育成独特的表型。最近，免疫基因组（ImmGen）计划联盟将食管MC列为典型的结缔组织MC之一。此外，我们的新研究发现 MrgprB2（人类 MrgprX2 的直系同源物）是一种 GPCR，仅在结缔组织 MC 中表达。现在已知许多基本促分泌剂（P 物质、VIP、PAMP、防御素等）和嗜酸性粒细胞阳离子蛋白仅通过 MrgprB2/X2 机制激活肥大细胞。我们发表的初步研究支持了这样的新假设：MrgprB2（人类中的 MrgprX2）介导食管炎症诱导的 MC 激活，并直接导致食管上皮屏障功能障碍和食管传入伤害性神经过度兴奋。我们将在小鼠和人类食道中解决这一假设，目标如下。在目标 1 中，我们将描述健康和发炎食管中 MrgprB2 阳性 MC 的分布、表型和对基本促分泌剂的激活反应（介质/细胞因子释放）。然后，我们将通过比较野生型和 MrgprB2mut 小鼠发炎食管中 MC 介质的释放来解决 MrgprB2 介导非 IgE 依赖性 MC 激活的假设。最后，我们将在嗜酸性粒细胞性食管炎模型中探讨嗜酸性粒细胞碱性蛋白（MBP、EPO、END）是否直接激活MrgprB2。在目标 2 中，我们将继续推进我们有趣的初步数据，证明反流引起的食管上皮屏障功能障碍（通透性增加）在 MrgprB2 mut 小鼠中显着减弱。为了确定非 MrgprB2 肥大细胞激活机制是否也有助于屏障破坏，我们将比较三组小鼠（野生型小鼠）和过敏性食管炎模型中反流性食管炎模型的通透性变化。肥大细胞不表达功能性 MrgprB2 mut 的小鼠；第三是肥大细胞缺陷的小鼠。在目标 3 中，我们将使用我们完善的细胞外记录技术以及我们新开发的双光子神经元成像方法，比较 MrgprB2 与过敏原诱发的肥大细胞激活对食管伤害性 C 纤维末端活动的影响。在目标 4 中，我们将比较 MrgprX2 在反流性食管活检标本和嗜酸性食管炎食管活检标本中的表达和功能，然后确定它们与食管组织学/症状的相关性。在转化方面，我们将通过使用我们新建立的人源化 MrgprX2 小鼠系来简要表征 MrgprX2 在小鼠食道中的表达和功能。阐明 MrgprB2/X2 介导的食管肥大细胞激活可能会激发对食管炎症性疾病新型靶向治疗策略的研究。