Molecular mechanisms of cytokine-induced modulation of T cell antigen receptor responsiveness

本研究计划的总体目标是了解在先天免疫反应中产生的炎症细胞因子如何影响细胞毒性T淋巴细胞的适应性免疫反应。细胞因子反应由“细胞因子信号抑制因子”（SOCS）家族蛋白调控。在研究缺乏SOCS1的小鼠中T细胞腔室的不受调节的稳态时，我们偶然发现：缺乏SOCS1的CD8 T细胞在调节T细胞稳态的细胞因子的作用下强劲增殖，这种增殖被炎症细胞因子放大；虽然这并不意外，但对照小鼠的CD8 T细胞也在炎症和稳态细胞因子的协同刺激下增殖。后者是出乎意料的，因为正常的T细胞需要两种信号——一种通过抗原受体，另一种通过共刺激受体。由于炎症和稳态细胞因子在炎症条件下（对感染或无菌炎症的反应）都可以获得，我们开始研究这种抗原和共刺激独立的naïve T细胞活化的生理意义和病理后果。在过去的十年中，我们已经证明(i)细胞因子刺激的T细胞对抗原的敏感性增加，因为它们对有限数量的抗原和弱激动性抗原肽作出反应，（ii）这种抗原非特异性刺激可以激活体内的自身反应性T细胞，（iii）这一过程由SOCS1调节。我们还发现，“细胞因子引发”的T细胞显示出更高的代谢适应性，其质膜发生显著变化，这可能影响T细胞抗原受体（TCR）信号传导。在本研究中，我们旨在了解细胞因子引发的T细胞抗原反应性增强的机制和分子基础。由于我们的候选方法显示出非常有限的范围，我们建议使用无偏倚基因组（ATACseq, RNAseq）和蛋白质组学（iTRAQ差异蛋白质组学）方法来全面了解细胞因子启动过程中发生的分子变化。选择的候选基因/蛋白质/途径将通过体外和体内模型测试其对细胞因子启动的贡献。该研究计划的重点是培养学生掌握基因组学和蛋白质组学、生物信息学分析等尖端技术。此外，他们还将接受与动物处理、T细胞生物学、流式细胞术、共聚焦显微镜、分子生物学技术和生物信息学分析相关的免疫学技术的培训。学员将获得适合学术生涯和行业工作的知识和技能。这项研究的结果将影响细胞因子如何被利用来促进免疫反应，以及它们的信号通路如何被靶向来控制异常的免疫反应。

The overall objective of this research program is to understand how inflammatory cytokines produced during innate immune responses impact on the adaptive immune responses of cytotoxic T lymphocytes. Cytokine responses are regulated by `suppressors of cytokine signaling' (SOCS) family proteins. While studying the deregulated homeostasis of the T cell compartment in mice lacking SOCS1, we made a fortuitous observation: SOCS1-deficient CD8 T cells proliferate robustly in response to cytokines that regulate T cell homeostasis and this is amplified by inflammatory cytokines; while this was not unexpected, CD8 T cells from control mice also proliferated in response to synergistic stimulation by inflammatory and homeostatic cytokines. The latter was unexpected because normal T cells require two signals - one via the antigen receptor and the other via a costimulatory receptor. As both inflammatory and homeostatic cytokines can become available during inflammatory conditions (in response to infections or sterile inflammation), we started investigating the physiological significance and pathological consequences of such antigen- and co-stimulation- independent activation of naïve T cells. Over the past decade, we have shown that (i) the cytokine-stimulated T cells acquire increased sensitivity to antigens as they respond to limiting amounts of antigens and weakly agonistic antigenic peptides, (ii) such antigen non-specific stimulation can activate autoreactive T cells in vivo, and (iii) this process is regulated by SOCS1. We have also found that the `cytokine-primed' T cells display increased metabolic fitness and marked changes in their plasma membrane that could impact T cell antigen receptor (TCR) signaling. In the proposed research, we aim to understand the mechanistic and molecular basis of the increased antigen responsiveness of cytokine-primed T cells. As our candidate approaches have shown very limited scope, we propose to use unbiased genomic (ATACseq, RNAseq) and proteomic (iTRAQ differential proteomics) approaches to gain a comprehensive view of the molecular changes that occur during cytokine priming. The selected candidate genes/proteins/pathways will be tested for their contribution to cytokine priming using in vitro assays and in vivo models. The proposed research program will put emphasis on training students in cutting-edge technologies of genomics and proteomics, and bioinformatics analyses. In addition they will be trained in several immunology techniques related to animal handling, T cell biology, flow cytometry, confocal microscopy, molecular biology techniques and bioinformatics analyses. The trainees will gain knowledge and skill set suitable for both academic career and industry jobs. The outcome of this research will impact on how cytokines could be exploited for boosting immune responses, and how their signaling pathways could be targeted to control aberrant immune responses.