The role of TRAF4 E3 ligase in IL-25-mediated allergic asthma

项目摘要/摘要： 大约一半的过敏性哮喘患者由于2型增多而被归类为Th2高(与Th2低)内型 炎症反应与健康对照组比较。气道2型炎症，以Th2升高为特征 (类型2)细胞因子(IL-4、IL-5、IL-9、IL-13)，由多种类型的肺细胞之间的相互作用介导， 包括结构细胞(如上皮细胞)和浸润性细胞(如Th2细胞、第2组固有淋巴样细胞 (ILC2))。尽管大多数Th2型高哮喘患者对目前基于类固醇的治疗有反应，但值得注意的是 这种内型的患者亚群表现出类固醇耐药，需要大剂量的类固醇来控制他们的 持续的症状。因此，开发新的节省类固醇的治疗方法以减少 与大剂量使用类固醇相关的副作用。白介素25(又称白介素17E) 被认为是经典Th2反应的重要上游调节因子。单核苷酸多态 IL-25受体(IL-25R)亚单位IL-17RB的单核苷酸多态(SNP)与哮喘的风险有关，这意味着靶向IL-17RB。 25在部分哮喘患者中可能具有临床意义。我们之前将Act1(TRAF3IP2)标识为 IL-25信号转导中的关键接头分子及其在IL-25介导的变态反应性肺损伤中的关键作用 发炎。令人兴奋的是，我们最近发现肿瘤坏死因子受体相关因子4(TRAF4)是一种新的 调节Act1向IL-25R募集的信号分子在IL-25-R中发挥关键作用 介导的呼吸道炎症。TRAF4蛋白的环状结构域是一种赋予蛋白质 具有E3连接酶活性。我们和其他人已经证明TRAF4是一种真正的E3连接酶，它可以诱导 多泛素化和其结合伙伴通过其环指结构域的泛素化。因此，我们 假设TRAF4在IL-25信号转导中作为E3连接酶发挥作用，影响Act1依赖和- 以细胞特异性方式促进2型过敏性哮喘的独立途径。为了检验这一假设，我们 提出以下具体目标：1)研究TRAF4在不同细胞中的内在作用 2)阐明TRAF4介导的IL-4的分子机制 25信令。TRAF4 E3连接酶在IL-25信号转导中的细胞和分子深入研究 将为启动和维持哮喘表型的事件提供重要的洞察力。此外， 我们建议的研究结果可能会提高识别新药靶点和开发新药物的潜力 用于治疗哮喘的非类固醇药物(例如，针对IL-25信号的通路特异性诱骗多肽)。

Project Summary/Abstract: Around half of allergic asthmatics are classified as Th2-high (vs. Th2-low) endotype due to increased type 2 inflammation as compared with healthy controls. Airway type 2 inflammation, characterized by increased Th2 (type 2) cytokines (IL-4, IL-5, IL-9, IL-13), is mediated by interplays between multiple cell types of the lung, including structural cells (e.g. epithelial cells), and infiltrating cells (e.g. Th2 cells, group 2 innate lymphoid cells (ILC2s)). Although most of Th2-high asthmatics are responsive to current steroid-based therapy, a notable subgroup of patients with this endotype show steroid-resistance and require high-dose steroids to control their persistent symptoms. Therefore, there is an unmet need for developing novel steroid-sparing therapy to reduce the side effects associated with high-dose use of steroids. Interleukin (IL)-25 (also called IL-17E) has been known as an important upstream regulator of the classic Th2 response. The single-nucleotide polymorphism (SNP) of IL-25 receptor (IL-25R) subunit IL-17RB has been linked to risk of asthma, implicating that targeting IL- 25 may be of clinical significance in a subset of asthmatics. We previously identified Act1 (TRAF3IP2) as an essential adaptor molecule in IL-25 signaling and established its critical role in IL-25-mediated allergic pulmonary inflammation. Excitingly, we recently found that TNF receptor associated factor 4 (TRAF4) was a novel signaling molecule meditating Act1 recruitment to IL-25R, exerting a critical functional role for IL-25- mediated airway inflammation. The RING domain of TRAF4 protein is a structural feature that confers protein with E3 ligase activity. We and others have shown that TRAF4 is a genuine E3 ligase which induces polyubiquitination and the ubiquitination of its binding partners through its RING finger domain. We thus hypothesize that TRAF4 functions as an E3 ligase in IL-25 signaling impacting both Act1-dependent and - independent pathways in a cell-specific manner to promote type 2 allergic asthma. To test this hypothesis, we propose the following Specific Aims: 1) Investigate the intrinsic role of TRAF4 in different cell compartments in type 2 allergic asthma; 2) Delineate the molecular mechanism of TRAF4-mediated IL- 25 signaling. The proposed in-depth cellular and molecular studies on the TRAF4 E3 ligase in IL-25 signaling will provide significant insight into the events that initiate and maintain the asthmatic phenotype. Moreover, the results from our proposed studies may improve the potential to identify new drug targets and develop novel steroid-sparing drugs (e.g pathway-specific decoy peptides targeting IL-25 signaling) for treatment of asthma.