Cytokine-induced modulation of T lymphocyte responses to antigens

背景：“幼稚”（无抗原经验）CD 8 T细胞的激活需要两个信号。信号1通过T细胞抗原（Ag）受体（TCR）递送，信号2通过共刺激受体递送。与这两个信号范例相反，我们已经表明，在先天免疫应答期间产生的某些炎性细胞因子（IL-6、IL-21）可以与稳态细胞因子（IL-7、IL-15）协同作用以诱导幼稚CD 8 T细胞的Ag非特异性增殖（Cell.信号了2007，19：806）。我们还表明，在IL-7或IL-15存在下，将初始CD 8 T细胞短暂暴露于IL-21或IL-6显著降低活化所需的TCR信号传导阈值（J.Immunol.2008，180：7958）。我们将这种烟碱介导的TCR应答性增加称为“细胞因子引发”，并提出该途径可以桥接先天性和适应性免疫应答（Crit.Rev.Immunol.2009，29：219）。 进度：在当前的授权期间，我们已经表明细胞因子引发降低了CD 5的表达，CD 5是TCR信号传导的负调节剂（Immunol. Cell. 2010，88：451）。我们还表明，经精氨酸引发的细胞获得了响应弱TCR配体的能力，并且使用自身免疫小鼠模型，细胞因子引发可在体内发生（J.Immunol.2010，185：357;同上，2011，186：5131）。我们最近的研究结果表明，（i）细胞因子引发增加脂筏含量和CD 45，TCR信号传导机制的两个关键组分，（ii）细胞因子引发诱导记忆细胞表型和减弱Ag诱导的耗竭，（iii）甘氨酸引发的细胞显示出升高的备用线粒体呼吸能力。 假设：我们假设，细胞因子引发的功能后果产生的空间和时间的变化，TCR信号沿着与分化途径和细胞能量代谢的调制，基因/蛋白质表达的具体变化是这些变化的基础。 目的：本研究计划的长期目标是了解细胞因子引发在生理和病理免疫反应中的机制和意义。 我们未来五年的短期目标是： 1.表征在马槟榔碱致敏的初始CD 8 T细胞中的TCR信号传导动力学。 2.阐明细胞因子启动如何调节它们的能量代谢。 3.定义由引发细胞因子诱导的基因/蛋白质表达的变化。 4.确定引发细胞因子在体内对弱TCR配体的CD 8 T细胞应答中的作用。 方法：作为实验系统，我们将使用TCR转基因小鼠来获得均匀的初始CD 8 T细胞群体。 1)我们将使用共聚焦显微镜来可视化的空间和时间分布的脂筏，CD 45和关键的TCR信号事件在T细胞和Ag负载的树突状细胞之间形成的免疫突触。 2)我们将使用Seahorse®细胞代谢分析仪来测量耗氧率（通过线粒体电子传递链测量ATP合成）和细胞外酸化率（测量产生细胞增殖所需的构建块的糖酵解）。 3)我们将使用微阵列进行基因表达分析，并使用质谱法进行蛋白质组学分析。 4)我们将使用表达转基因TCR识别的同源Ag或弱激动剂的病毒感染野生型或特异性细胞因子缺陷小鼠，并评估体内Ag特异性CD 8 T细胞的活化和功能分化。 重要性：这项研究计划将提供深入了解炎症细胞因子'总理'幼稚的CD 8 T细胞随后遇到入侵病原体的抗原的机制。

Background: Activation of ‘naïve’ (antigen-inexperienced) CD8 T cells requires two signals. Signal 1 is delivered via the T cell antigen (Ag) receptor (TCR), and signal 2 is delivered via co-stimulatory receptors. Contrary to this two signal paradigm, we have shown that certain inflammatory cytokines produced during innate immune response (IL-6, IL-21) can synergize with homeostatic cytokines (IL-7, IL-15) to induce Ag non-specific proliferation of naïve CD8 T cells (Cell. Signal. 2007,19:806). We have also shown that a brief exposure of naïve CD8 T cells to IL-21 or IL-6 in the presence of IL-7 or IL-15 markedly decreases the TCR signaling threshold required for activation (J. Immunol. 2008,180: 7958). We refer to this cytokine-mediated increase in TCR responsiveness as ‘cytokine priming’, and have proposed that this pathway may bridge innate and adaptive immune responses (Crit. Rev. Immunol. 2009,29: 219). Progress: During the current grant period, we have shown that cytokine priming reduces the expression of CD5, a negative regulator of TCR signaling (Immunol. Cell. Biol. 2010,88: 451). We have also shown that cytokine-primed cells acquire the capacity to respond to weak TCR ligands, and that cytokine priming could occur in vivo using mouse models of autoimmunity (J. Immunol. 2010, 185:357; ibid. 2011,186:5131). Our recent findings indicate that (i) cytokine priming increases the lipid raft content and CD45, two key components of the TCR signaling machinery, (ii) cytokine priming induces a memory cell phenotype and attenuates Ag-induced exhaustion, (iii) cytokine-primed cells display show elevated spare mitochondrial respiratory capacity. Hypothesis: We hypothesize that the functional consequences of cytokine priming arise from spatial and temporal changes in TCR signaling along with modulation of differentiation pathways and cellular energy metabolism, and that specific changes in gene/protein expression underlie these alterations. Objectives: The long-term objective of this research program is to understand the mechanisms and the significance of cytokine priming in physiological and pathological immune responses. Our short-term goals for the next 5 years are: 1. Characterize the TCR signaling dynamics in cytokine-primed naive CD8 T cells. 2. Elucidate how cytokine priming modulates their energy metabolism. 3. Define the changes in gene/protein expression induced by the priming cytokines. 4. Determine the role of priming cytokines in CD8 T cell responses to weak TCR ligands in vivo. Methodology: As experimental system, we will use TCR transgenic mice to obtain a uniform population of naïve CD8 T cells. 1) We will use confocal microscopy to visualize the spatial and temporal distribution of lipid rafts, CD45 and key TCR signaling events at the immune synapse formed between T cells and Ag-loaded dendritic cells. 2) We will use the Seahorse® cell metabolism analyzer to measure oxygen consumption rate (a measure of ATP synthesis via mitochondrial electron transport chain) and extracellular acidification rate (a measure of glycolysis that generates building blocks needed for cell proliferation). 3) We will carry out gene expression analysis using microarrays, and proteomic analysis by mass spectrometry. 4) We will use a virus expressing either the cognate Ag recognized by the transgenic TCR, or a weak agonist, to infect wild type or specific cytokine deficient mice, and evaluate activation and functional differentiation of Ag-specific CD8 T cells in vivo. Significance: This research program will provide insight into the mechanisms by which inflammatory cytokines ‘prime’ naïve CD8 T cells for the ensuing encounter with Ags of invading pathogens.