Tec Kinases ltk and RlK in Mast Cell Signaling

过敏性哮喘是一种复杂的疾病，涉及淋巴细胞介导的局部炎症反应， 嗜酸性粒细胞和肥大细胞。这种反应的一个关键成分是辅助性T细胞2型(Th2)细胞因子， 包括IL-4、IL-5、IL-9和IL-13，由T细胞和肥大细胞产生。TEC家族酪氨酸激酶 和RLK，在激活T细胞受体下游的磷脂酶C-y1中起重要作用。ITK/RLK- 缺陷的T细胞表现为TCR信号受损，导致细胞因子产生显著减少和 在清除病原性感染方面存在缺陷。有趣的是，未免疫的ITK-/-和ITK-/-RLK-/-小鼠 提示Th2型细胞因子产生过多的异常，如生发中心增生 脾、嗜酸性粒细胞增多和血清IgE抗体水平升高。这些数据，再加上ITK 和RLK也在肥大细胞中表达，提示以下假设：ITK和/或RLK可能在肥大细胞中起关键作用 T细胞对IL-4的产生导致Th2细胞分化和细胞因子的产生，但也可能起到一定作用 肥大细胞细胞因子的产生。为了检验这一假设，我们建议确定异常是否 在未免疫的ITK-/-和ITK-/-RLK-/-小鼠中可见是由于T细胞固有缺陷、肥大细胞缺陷或 两者都有。第二，我们发现ITK-/-骨髓来源的肥大细胞分泌增强的IL-4、IL-6和 刺激FceRI后产生IL-13。基于这些数据，我们假设ITK是最优的 激活SHIP1/DOK-1通路，已知可以减弱肥大细胞的反应。为了测试这一想法，我们将 检测ITK-/-肥大细胞在刺激反应中脱颗粒和细胞因子产生的变化 单独使用IgE，IgE+抗原，SCF，以及FceRI和FcgRII共同聚集。生化 分析将直接解决ITK在SHIP1依赖的途径中的作用。这些项目的总体目标是 研究是为了加深我们对信号通路的理解，这些信号通路可能有助于 研究过敏疾病，并提出处理和/或预防过敏反应的机制。

Allergic asthma is a complex disease involving a localized inflammatory response mediated by lymphocytes, eosinophils and mast cells. One critical component of this response is the T helper type 2 (Th2) cytokines, including IL-4, IL-5, IL-9, and IL-13, produced by T cells and mast cells. The Tec family tyrosine kinases, Itk and Rlk, play important roles in activating phospholipase C-y1 downstream of the T cell receptor. Itk/Rlk- deficient T cells show impaired TCR signaling, leading to substantially reduced cytokine production and defects in clearing pathogenic infections. Interestingly, unimmunized Itk-/- and Itk-/-Rlk-/- mice exhibit abnormalities suggestive of excess Th2-type cytokine production, such as germinal center hyperplasia in the spleen, eosinophilia, and elevated levels of serum IgE antibodies. These data, together with the fact that Itk and Rlk are also expressed in mast cells, suggest the following hypothesis: Itk and/or Rlk may be critical in T cells for IL-4 production leading to Th2 cell differentiation and cytokine production, but may also play a role in mast cell cytokine production. To test this hypothesis, we propose to determine whether the abnormalities seen in unimmunized Itk-/- and Itk-/-Rlk-/- mice are due to a T cell-intrinsic defect, a defect in mast cells, or both. Second, we find that Itk-/- bone marrow-derived mast cells secrete enhanced levels of IL-4, IL-6, and IL-13 following FceRI stimulation. Based on these data, we hypothesize that Itk is required for optimal activation of the SHIP1/Dok-1 pathway, known to attenuate mast cell responses. To test this idea, we will examine Itk-/- mast cells for alterations in degranulation and cytokine production in response to stimulation with IgE alone, IgE plus antigen, SCF, as well as to FceRI and FcgRII co-aggregation. Biochemical analyses will directly address the role of Itk in the SHIP1-dependent pathway. The overall goal of these studies is to further our understanding of signaling pathways that may contribute to the development of allergic diseases, and to suggest mechanisms for the manipulation and/or prevention of allergic responses.