Tp12-dependent IFN-g production: contribution to host defense and autoimmunity

描述(申请人提供)：细胞因子几乎调节免疫的方方面面，包括淋巴发育、动态平衡、分化、耐受和记忆。感染过程中产生的白介素12通过诱导促炎细胞因子干扰素-γ来决定适应性免疫反应的类型和持续时间。通过IL-12/干扰素-γ传递信号的缺陷与感染易感性有关。同样值得关注的是，IL-12/干扰素-γ的失调与自身免疫的发展有关。因此，全面了解IL-12信号通路对于开发新的治疗策略至关重要。目前，我们对IL-12信号中间体的了解还很不完整。为了深入了解IL-12的S作用的分子基础，我们鉴定了丝氨酸激酶Tpl2是IL-12诱导的基因。由于其作为一种激酶的功能，我们假设Tpl2是IL-12信号本身的关键中间体，是产生干扰素-γ、抵抗感染以及在病理环境中发展自身免疫性疾病所必需的。为了扩大我们对Tpl2与IL-12介导的干扰素-γ产生相关的分子生物学的理解，我们建议(1)定义Tpl2与IL-12信号转导的生化途径；(2)研究Tpl2在T和NK细胞产生干扰素-γ中的作用及其在宿主防御和自身免疫发展中的作用。初步数据证实，Tpl2在T细胞和NK细胞中都受IL-12的调节，是T细胞产生干扰素-γ所必需的。我们将使用标准的生化技术，包括免疫印迹和激酶检测来分析Tpl2的信号作用。我们将通过观察Tpl2缺陷小鼠在感染性疾病和自身免疫模型中的免疫反应来进一步验证我们的假设。由于IL-12在自身免疫中的致病作用，阻断IL-12信号通路将是一种有吸引力的干预手段。由于激酶与炎症性疾病的发生发展密切相关，因此，对其活性的调节已成为新药设计中的一个活跃研究领域。如果这项拟议的工作证明了Tpl2通过调节IL-12诱导的干扰素-γ的产生而在自身免疫性疾病的发生发展中起关键作用，那么它将为开发用于治疗人类自身免疫性疾病的Tpl2选择性激酶抑制剂提供理论基础。

DESCRIPTION (provided by applicant): Cytokines mediate virtually every facet of immunity including lymphoid development, homeostasis, differentiation, tolerance and memory. Interleukin (IL)-12 production during infection determines the type and duration of adaptive immune response through the induction of the pro-inflammatory cytokine, interferon(IFN)-gamma. Defects in signaling via IL-12/IFN-gamma are associated with susceptibility to infections. Of equal concern is that dysregulation of IL-12/IFN-gamma is associated with the development of autoimmunity. Therefore, a comprehensive understanding of the IL-12 signaling pathway is crucial for the development of novel treatment strategies. Currently, our knowledge of IL-12 signaling intermediates is quite incomplete. In an attempt to gain insight into the molecular basis of IL-12's action we identified the serinethreonine kinase, Tpl2, as an IL-12-inducible gene. Because of its function as a kinase, we hypothesize that Tpl2 is a critical intermediate in IL-12 signaling per se that is required for IFN-gamma production, resistance to infection, and, in pathologic settings, the development of autoimmune disease. In order to broaden our understanding of the molecular biology of Tpl2 as it relates to IL-12-mediated IFN-gamma production we propose (1) to define the biochemical pathway that links Tpl2 to IL-12 signaling and (2) to characterize the role of Tpl2 in IFN-gamma production by T and NK cells and its contribution to host defense and the development of autoimmunity. Preliminary data confirm that Tpl2 is regulated by IL-12 in both T and NK cells and is required for the production of IFN-gamma by T cells. We will use standard biochemical techniques including immunoblotting and kinase assay to dissect the signaling role of Tpl2. We will further test our hypotheses by observing the immune responses of Tpl2-deficient mice in murine models of infectious disease and autoimmunity. Due to its causative role in autoimmunity, blockade of IL-12 signaling would be an attractive means for intervention. Because kinases have been implicated in the development of inflammatory diseases, the modulation of kinase activity has become an active area of research in new drug design. If the proposed work demonstrates that Tpl2 is critical in the development of autoimmune disease through the regulation of IL-12-induced production of IFN-gamma, then it will provide a rationale for the development of a Tpl2 selective kinase inhibitor for use in the treatment of human autoimmune diseases.