Garcia Carlos A, Wang Huizhi, Benakanakere Manjunatha R, Barrett Elyse, Kinane Denis F, Martin Michael
Department of Microbiology and Immunology, University of Louisville School of Medicine, Louisville, KY 40292, USA.
J Immunol. 2009 Oct 1;183(7):4475-82. doi: 10.4049/jimmunol.0901283. Epub 2009 Sep 4.
IL-12p70 is an immunoregulatory cytokine that has been shown to induce IL-10 production from CD4+ T cells, yet the underlying cellular mechanisms controlling this process are poorly understood. In the present study, we demonstrate that IL-12p70 induces IL-10 production from human memory CD4+ T cells via a PI3K-dependent signaling mechanism. Specifically, stimulation of human memory CD4+ T cells in the presence of IL-12p70 lead to increased PI3K activity and the subsequent phosphorylation and inactivation of the downstream constitutively active serine/threonine kinase, glycogen synthase kinase-3beta (GSK3beta). Inhibition of PI3K prevented the inactivation of GSK3beta by IL-12p70, as well as the subsequent ability of IL-12p70 to augment IL-10 levels by memory CD4+ T cells. Moreover, ectopic expression of a constitutively active form of GSK3beta abrogated the ability of IL-12p70 to increase IL-10 production by TCR-stimulated CD4+ T cells. In contrast, direct inhibition of GSK3 mimicked the effect of IL-12p70 on IL-10 production by memory CD4+ T cells. Analysis of downstream transcription factors identified that the ability of IL-12p70 to inactivate GSK3beta lead to increased levels of c-jun. The ability of IL-12p70 to inactivate GSK3beta and induce c-jun levels was required for IL-12 to augment IL-10 production by human memory CD4+ T cells, since small interfering RNA-mediated gene silencing of c-jun abrogated this process. These studies identify the cellular mechanism by which IL-12 induces IL-10 production from human memory CD4+ T cells.
白细胞介素-12p70是一种免疫调节细胞因子，已被证明可诱导CD4+ T细胞产生白细胞介素-10，但控制这一过程的潜在细胞机制尚不清楚。在本研究中，我们证明白细胞介素-12p70通过PI3K依赖性信号传导机制诱导人记忆性CD4+ T细胞产生白细胞介素-10。具体而言，在白细胞介素-12p70存在的情况下刺激人记忆性CD4+ T细胞会导致PI3K活性增加，随后下游组成型活性丝氨酸/苏氨酸激酶糖原合酶激酶-3β（GSK3β）发生磷酸化并失活。抑制PI3K可阻止白细胞介素-12p70使GSK3β失活，以及白细胞介素-12p70随后增强记忆性CD4+ T细胞白细胞介素-10水平的能力。此外，组成型活性形式的GSK3β的异位表达消除了白细胞介素-12p70通过TCR刺激的CD4+ T细胞增加白细胞介素-10产生的能力。相反，直接抑制GSK3模拟了白细胞介素-12p70对记忆性CD4+ T细胞白细胞介素-10产生的影响。对下游转录因子的分析表明，白细胞介素-12p70使GSK3β失活的能力导致c-jun水平升高。白细胞介素-12p70使GSK3β失活并诱导c-jun水平的能力是白细胞介素-12增强人记忆性CD4+ T细胞白细胞介素-10产生所必需的，因为小干扰RNA介导的c-jun基因沉默消除了这一过程。这些研究确定了白细胞介素-12诱导人记忆性CD4+ T细胞产生白细胞介素-10的细胞机制。
