Dual Oxidase in Airway Epithelial Injury and Inflammation

描述（由申请人提供）：NADPH氧化酶DUOX1在呼吸道上皮中显著表达，并通过促进h2o2依赖性信号通路介导伤口反应和各种炎症介质或粘蛋白基因的产生，在先天气道上皮对损伤或感染刺激的反应中被调用。在上一个资助周期的研究中，我们已经确定了DUOX1激活促进表皮生长因子受体（EGFR）激活的氧化机制，作为伤口反应和炎症介质产生的关键事件，并观察到过敏性哮喘模型中DUOX1表达增加与EGFR激活增加和粘液化生有关。呼吸道上皮通过产生白细胞介素-33 （IL-33）等上皮细胞因子，在协调对空气中过敏原的先天和适应性免疫应答中起着关键作用。IL-33最近被确定为过敏性炎症动物模型的关键介质，也是哮喘的主要易感基因。IL-33通常存在于肺上皮细胞的细胞核内，在各种刺激和过敏原的作用下迅速分泌，作为一种警报蛋白，刺激靶细胞上的ST2受体，诱导先天TH2细胞优势免疫应答。然而，参与调节IL-33分泌的细胞机制仍然知之甚少，我们现在提供的初步证据表明，duox1依赖性H2O2的产生是对两种常见过敏原（交替孢螨和房尘螨）的上皮IL-33分泌的关键介质。我们的研究进一步表明，蛋白酶激活受体（PAR）和瞬时受体电位（TRP）通道在近端对这些过敏原的反应中，导致DUOX1激活和IL-33分泌的重要性。此外，我们有初步证据表明h2o2介导的EGFR激活是DUOX1激活促进核输出和/或IL-33分泌的关键机制。本更新申请的主要目的是建立DUOX1激活在介导各种蛋白酶过敏原IL-33分泌和随后的过敏性炎症中的共同作用（Aim 1），阐明DUOX1激活促进IL-33核输出和分泌的下游氧化还原机制，重点研究EGFR激活的作用（Aim 2）。并通过确定这些患者鼻上皮过敏原反应中DUOX1表达与激活之间的关系，在过敏性哮喘患者的研究中扩展我们的发现（目的3）。这些研究的成功完成将确定DUOX1作为治疗哮喘和/或其恶化的一个新的和有吸引力的治疗靶点。

DESCRIPTION (provided by applicant): The NADPH oxidase DUOX1 is prominently expressed within the respiratory epithelium and has been invoked in innate airway epithelial responses to injury or infectious stimuli, by promoting H2O2-dependent signaling pathways that mediate wound responses and production of various inflammatory mediators or mucin genes. In studies during the previous funding cycle, we have identified oxidative mechanisms by which DUOX1 activation promotes the activation of epidermal growth factor receptor (EGFR) as a critical event in wound responses and inflammatory mediator production, and observed increased DUOX1 expression in models of allergic asthma in association with increased EGFR activation and mucus metaplasia. The respiratory epithelium is critical in coordinating innate and adaptive immune responses to airborne allergens, by production of epithelial cytokines such as interleukin-33 (IL-33). IL-33 was recently identified as a critical mediator in animal models of allergic inflammation, and a major susceptibility gene for asthma. IL-33 is normally present within the nuclei of pulmonary epithelial cells, and is rapidly secreted in response to various stimuli and allergens to function as an alarmin that stimulates ST2 receptors on target cells to induce innate TH2 cell-dominant immune responses. The cellular mechanisms involved in regulating IL-33 secretion are still poorly understood, however, and we now present preliminary evidence demonstrating the importance of DUOX1-dependent production of H2O2 as a critical mediator in epithelial IL-33 secretion in response to two common allergens, Alternaria alternata and Dermatophagoides pteronyssinus (house dust mite). Our studies further indicate the importance of protease-activated receptors (PAR) and transient receptor potential (TRP) channels in proximal responses to these allergens leading to DUOX1 activation and IL-33 secretion. In addition, we have preliminary evidence demonstrating H2O2-mediated EGFR activation as a critical mechanism by which DUOX1 activation promotes nuclear export and/or secretion of IL-33. The main objectives of this renewal application are to establish the common role of DUOX1 activation in mediating IL-33 secretion and subsequent allergic inflammation by various protease allergens (Aim 1), to clarify the downstream redox mechanisms by which DUOX1 activation promotes IL-33 nuclear export and secretion, focusing on the role of EGFR activation (Aim 2), and to expand our findings in studies with human subjects with allergic asthma by determining associations between DUOX1 expression and activation in nasal epithelial allergen responses in these patients (Aim 3). Successful accomplishment of these studies would identify DUOX1 as a novel and attractive therapeutic target in the management of asthma and/or its exacerbations.