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。这种应答的一个关键成分是辅助性T细胞2型（Th 2）细胞因子， 包括由T细胞和肥大细胞产生的IL-4、IL-5、IL-9和IL-13。Tec家族酪氨酸激酶 和Rlk在活化T细胞受体下游的磷脂酶C-y 1中起重要作用。Itk/Rlk- 缺陷型T细胞显示受损的TCR信号传导，导致细胞因子产生显著减少， 清除病原体感染的缺陷。有趣的是，未免疫的Itk-/-和Itk-/-Rlk-/-小鼠表现出 提示Th 2型细胞因子过度产生的异常，如在 脾脏、嗜酸性粒细胞增多和血清IgE抗体水平升高。这些数据，以及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细胞产生IL-4导致Th 2细胞分化和细胞因子产生，但也可能发挥作用 在肥大细胞细胞因子产生中。为了验证这一假设，我们建议确定是否异常 在未免疫的Itk-/-和Itk-/-Rlk-/-小鼠中观察到的免疫缺陷是由于T细胞内在缺陷、肥大细胞缺陷或 两者第二，我们发现Itk-/-骨髓来源的肥大细胞分泌增强水平的IL-4、IL-6， FceRI刺激后的IL-13。基于这些数据，我们假设Itk是最佳的 SHIP 1/Dok-1通路的激活，已知其减弱肥大细胞反应。为了验证这个想法，我们将 检查Itk-/-肥大细胞对刺激应答的脱粒和细胞因子产生的改变 与单独的IgE、IgE加抗原、SCF以及与FceRI和FcgRII共聚集。生化 这些分析将直接解决Itk在SHIP 1依赖性途径中的作用。这些活动的总体目标 研究是为了进一步了解可能有助于发展的信号通路， 过敏性疾病，并提出操纵和/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.