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

描述（由申请人提供）：细胞因子介导免疫的几乎所有方面，包括淋巴发育、稳态、分化、耐受和记忆。感染期间白细胞介素（IL）-12的产生通过诱导促炎细胞因子干扰素（IFN）-γ来决定适应性免疫应答的类型和持续时间。通过IL-12/IFN-γ的信号传导缺陷与感染易感性相关。同样值得关注的是，IL-12/IFN-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信号传导中间体的了解还相当不完整。为了深入了解IL-12作用的分子基础，我们鉴定了丝氨酸苏氨酸激酶Tp 12作为IL-12诱导基因。由于其作为激酶的功能，我们假设Tp 12是IL-12信号传导本身的关键中间体，其是IFN-γ产生、抗感染和在病理环境中自身免疫性疾病发展所需的。为了拓宽我们对Tp 12的分子生物学的理解，因为它涉及IL-12介导的IFN-γ产生，我们提出（1）定义将Tp 12与IL-12信号传导联系起来的生物化学途径和（2）表征Tp 12在T和NK细胞产生IFN-γ中的作用及其对宿主防御和自身免疫发展的贡献。初步数据证实，Tpl 2在T细胞和NK细胞中均受IL-12调节，并且是T细胞产生IFN-γ所需的。我们将使用标准生物化学技术，包括免疫印迹和激酶测定来剖析Tp 12的信号传导作用。我们将通过观察感染性疾病和自身免疫的鼠模型中Tp 12缺陷型小鼠的免疫应答来进一步测试我们的假设。由于其在自身免疫中的致病作用，IL-12信号传导的阻断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展有关，因此激酶活性的调节已成为新药设计中的一个活跃的研究领域。如果所提出的工作证明Tpl 2通过调节IL-12诱导的IFN-γ的产生在自身免疫性疾病的发展中是关键的，那么它将为开发用于治疗人类自身免疫性疾病的Tpl 2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.