REGULATION OF CYTOKINE GENE EXPRESSION IN HUMAN T CELLS BY IL-4 AND IL12

IL-4和IL12对人T细胞中细胞因子基因表达的调节

• 批准号: 6293751
• 负责人: R. P DONNELLY
• 金额: --
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/6293751
• 关键词: CD3 molecule; T lymphocyte; gene expression; human tissue; immunoregulation; interferon gamma; interleukin 1; interleukin 10; interleukin 12; interleukin 2; leukocyte activation /transformation; protein biosynthesis; tumor necrosis factor alpha

IL-12 is known to up-regulate synthesis of interferon-gamma (IFN-g) in activated T cells; however, the effects of IL-12 on expression of other cytokines are less well defined. In this project, we are examining the effects of IL-12 on production of multiple cytokines, including IFN-g, IL-2, IL-4, IL-10 and IL-13, by purified, normal, human CD3+ T cells. Although resting T cells are largely IL-12-nonresponsive, anti-CD3-activated T cell blasts are highly IL-12-responsive as demonstrated by the ability of IL-12 to induce STAT4-mediated DNA-binding activity. We have found that activation of purified human T lymphocytes on immobilized anti-CD3 mAb induces rapid expression of TNF-a and IL-2 mRNA, and more gradual increases in mRNA levels for IFN-g, IL-10 and IL-13. Changes in mRNA expression levels were measured by RNase protection assay using primer template sets that facilitate analysis of multiple cytokine genes simultaneously. We have found that IL-12 markedly up-regulates expression of IFN-g and IL-10, and down-regulates production of IL-2. Inhibition of IL-2 production by IL-12 correlates directly with increased production of IL-10. Moreover, neutralization of IL-10 activity with anti-IL-10 antibodies normalizes IL-2 production in IL-12-treated T cells demonstrating that the inhibitory effects of IL-12 are IL-10-mediated. Thus, we have found that IL-12 simultaneously up-regulates production of IFN-g and IL-10, and, by a direct IL-10-dependent pathway, feedback inhibits production of IL-2. The fact that IL-12 differentially regulates synthesis of IFN-g and IL-2 in T cells demonstrates that IL-12 does not globally enhance expression of all Th1-type lymphokines. Furthermore, the ability of IL-12 to up-regulate production of IL-10 provides a mechanism for limiting the IL-2-dependent clonal expansion of activated T cells, and defines a novel cytokine regulatory pathway that is inducible by IL-12. In future studies, we plan to further define the effects of IL-12 on production of other cytokines, particularly the Th2-type cytokines IL-4 and IL-13 by activated T cells, and to compare the effects of IL-12 with that of other macrophage-derived immunoregulatory cytokines, most notably IL-1 beta and TNF-alpha. We will also further explore the functional consequences of increased IL-10 production in IL-12-treated T cells. The results of these studies will broaden our current understanding of the actions of IL-12 on immune effector cells. This information may be useful in interpreting any therapeutic activity induced by IL-12 in clinical trials that are now underway. It may also provide insight to the physiological basis for certain toxicities associated with high dose IL-12 therapy. Furthermore, analysis of the effects of IL-12 on cytokine expression in vitro may facilitate identification of surrogate markers of IL-12 bioactivity that could be useful in monitoring the potency of recombinant IL-12 in human recipients.

已知IL-12在活化的T细胞中上调干扰素-γ（IFN-g）的合成;然而，IL-12对其他细胞因子表达的影响不太明确。 在这个项目中，我们正在研究IL-12对纯化的正常人CD 3 + T细胞产生多种细胞因子，包括IFN-γ，IL-2，IL-4，IL-10和IL-13的影响。 尽管静息T细胞在很大程度上是IL-12非应答性的，但抗CD 3活化的T细胞母细胞是高度IL-12应答性的，如IL-12诱导STAT 4介导的DNA结合活性的能力所证明的。 我们已经发现，纯化的人T淋巴细胞在固定的抗CD 3 mAb上的活化诱导TNF-α和IL-2 mRNA的快速表达，以及IFN-γ、IL-10和IL-13的mRNA水平的更渐进的增加。 mRNA表达水平的变化通过使用引物模板组的RNA酶保护测定来测量，所述引物模板组有助于同时分析多个细胞因子基因。 我们已经发现IL-12显著上调IFN-γ和IL-10的表达，并下调IL-2的产生。 IL-12对IL-2产生的抑制与IL-10产生的增加直接相关。 此外，用抗IL-10抗体中和IL-10活性使IL-12处理的T细胞中的IL-2产生正常化，表明IL-12的抑制作用是IL-10介导的。 因此，我们发现IL-12同时上调IFN-γ和IL-10的产生，并且通过直接的IL-10依赖性途径，反馈抑制IL-2的产生。 IL-12差异调节T细胞中IFN-γ和IL-2的合成的事实证明IL-12并不全面增强所有Th 1型淋巴因子的表达。 此外，IL-12上调IL-10产生的能力提供了限制活化T细胞的IL-2依赖性克隆扩增的机制，并定义了可由IL-12诱导的新的细胞因子调节途径。 在未来的研究中，我们计划进一步确定IL-12对其他细胞因子，特别是活化T细胞产生的Th 2型细胞因子IL-4和IL-13的影响，并将IL-12的作用与其他巨噬细胞衍生的免疫调节细胞因子，特别是IL-1 β和TNF-α的作用进行比较。 我们还将进一步探索IL-12处理的T细胞中IL-10产生增加的功能后果。 这些研究的结果将拓宽我们目前对IL-12对免疫效应细胞作用的理解。 这些信息可能有助于解释目前正在进行的临床试验中IL-12诱导的任何治疗活性。 它还可以提供与高剂量IL-12治疗相关的某些毒性的生理基础的见解。 此外，IL-12对细胞因子表达的影响的体外分析可能有助于鉴定IL-12生物活性的替代标记物，其可能用于监测重组IL-12在人受体中的效力。