MAP3K8 in immunoregluation, host defense and autoimmunity

MAP3K8 在免疫调节、宿主防御和自身免疫中的作用

• 批准号: 8157152
• 负责人: John O'Shea
• 金额: $ 26.81万
• 依托单位: NATIONAL INSTITUTE OF ARTHRITIS AND MUSCULOSKELETAL AND SKIN DISEASES
• 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/8157152
• 关键词: Autoimmunity; Host Defense; MAP3K8 gene

Cytokines are secreted proteins that regulate cell growth and differentiation. These factors are especially important in regulating immune and inflammatory responses, regulating lymphoid development and differentiation. Cytokines also regulate immune homeostasis, tolerance, and memory. Not surprisingly, cytokines are critical in the pathogenesis of autoimmune diseases such as rheumatoid arthritis, systemic lupus erythematosus, inflammatory bowel disease and psoriasis. Understanding the molecular basis of cytokine action provides important insights into the pathogenesis of immune-mediated disease and offers new therapeutic targets. Cytokine receptors are associated with Janus family kinases (Jaks), which initiate signaling (see project AR041106-14). Following activation of Jaks, the next step in signaling is the activation of a family of transcription factors called Stats (signal transducers and activators of transcription) (see project AR041159-01). To better understand the molecular actions of cytokines, we performed transcriptional profiling of mouse and human T cells activated by interleukin (IL)-12. We identified a large number of inducible genes, some of which had been previously recognized as being IL-12-inducible. One such gene was the gene encoding the serine/threonine kinase Cot/Tpl2. This kinase was directly inducible by IL-12 and inhibited by IL-4. As IL-12 activates the transcription factor Stat4, we also assessed the dependence of inducible MAP3K8 expression in Stat4-deficient mice. Furthermore, using chromatin immunoprecipitation, we found that MAP3K8 was a direct Stat4 target. To define the role of MAP3K8, we studied MAP3K8 knockout mice. We found that Thelper1 differentiation of MAP3K8-/- mice was markedly deficient. We further found that this was associated with failure to upregulate the transcription factors Stat4 and Tbox21 (T-bet), thus explaining the failure to properly generate IFNg. Challenge of MAP3K8-deficient mice with Toxoplasma gondii showed that these mice had increased susceptibility to this model pathogen, consistent with the impaired ability to generate IFNg. Conversely, in the model of autoimmune disease that mimics multiple sclerosis, experimental autoimmune encephalomyelitis or EAE, MAP3K8-knockout mice had reduced severity of disease. We further established that OVA-immunized Tpl2(-/-) mice express high levels of IgE and develop more severe bronchoalveolar eosinophilic inflammation than Tpl2(+/+) controls, when challenged with OVA intranasally. Bronchoalveolar exudates and supernatants of OVA-stimulated splenocytes from immunized Tpl2(-/-) mice express elevated levels of IL-4 and IL-5, suggesting that Tpl2 ablation promotes the Th2 polarization of the T cell response. Anti-CD3 stimulation of CD4(+) T cells of wild-type and Tpl2 knockout mice revealed that Tpl2 ablation gives rise to a cell autonomous T cell defect that is primarily responsible for the Th2 polarization of the T cell response to Ag. This observation was further supported by experiments addressing the expression of Th1 and Th2 cytokines in OVA-stimulated mixed cultures of CD4(+) T cells from Tpl2(+/+)/OT2 or Tpl2(-/-)/OT2 mice and dendritic cells from Tpl2(+/+) or Tpl2(-/-) mice. Further studies revealed that Th1 cells express significantly higher levels of Tpl2 than Th2 cells. As a result, Tpl2(-/-) Th1 cells exhibit a stronger defect in ERK activation by anti-CD3 than Th2 cells and express low levels of T-bet. Given that the development of Th1 and Th2 cells depends on positive feedback signals from the T cells, themselves, the functional defect of the Tpl2(-/-) Th1 cells provides a mechanistic explanation for the T cell autonomous Th2 polarization in Tpl2(-/-) mice. We also investigated the role of MAP3K8 in innate immune cells. To address this issue, we infected Tpl2(-/-) mice with the model pathogen Listeria monocytogenes. We found that Tpl2(-/-) mice infected i.v. with L. monocytogenes had increased pathogen burdens compared with wild-type mice and rapidly succumbed to infection. Enhanced susceptibility correlated with impaired signaling through TLR2 and nucleotide-binding oligomerization domain 2, two receptors previously shown to mediate Listeria recognition. Surprisingly, TNF production in response to infection was not significantly impaired, even though Tpl2 has been implicated in the regulation of TNF. We found that the role of Tpl2 has cell-type specific effects in regulating TNF and transduces signals from some, but not all, pattern recognition receptors (PRR). In contrast to the cell-type- and receptor-specific regulation of TNF, we found that Tpl2 is essential for IL-1beta production from both macrophages and dendritic cells. These studies implicate Tpl2 as an important mediator for collaboration of pattern recognition receptors with danger-associated molecular patterns to induce TNF and IL-1beta production and optimal host defense.

细胞因子是调节细胞生长和分化的分泌蛋白质。这些因素对于调节免疫和炎症反应，调节淋巴发育和分化尤为重要。 细胞因子还调节免疫稳态，耐受性和记忆力。毫不奇怪，细胞因子在自身免疫性疾病（例如类风湿关节炎，全身性红斑狼疮，炎症性肠病和牛皮癣）的发病机理中至关重要。 了解细胞因子作用的分子基础为免疫介导疾病的发病机理提供了重要的见解，并提供了新的治疗靶标。 细胞因子受体与Janus家族激酶（JAKS）有关，该激酶启动信号（请参阅Project AR041106-14）。 激活JAKS后，信号传导的下一步是激活称为统计数据的转录因子（信号换能器和转录激活因子）（请参阅Project AR041159-01）。 为了更好地了解细胞因子的分子作用，我们对白介素（IL）-12激活的小鼠和人T细胞进行了转录分析。 我们确定了大量诱导基因，其中一些基因以前被认为是IL-12诱导的。这样的基因是编码丝氨酸/苏氨酸激酶COT/TPL2的基因。该激酶被IL-12直接诱导，并被IL-4抑制。 随着IL-12激活转录因子STAT4，我们还评估了STAT4缺陷小鼠中诱导型MAP3K8表达的依赖性。 此外，使用染色质免疫沉淀，我们发现MAP3K8是直接的STAT4靶标。为了定义MAP3K8的作用，我们研究了MAP3K8敲除小鼠。 我们发现MAP3K8 - / - 小鼠的thelper1分化显着缺陷。 我们进一步发现，这与未能上调转录因子STAT4和TBOX21（T-BET）有关，从而解释了无法正确生成IFNG的失败。 用弓形虫弓形虫对MAP3K8缺陷小鼠的挑战表明，这些小鼠对该模型病原体的敏感性增加，这与产生IFNG的能力受损一致。 相反，在模仿多发性硬化症，实验性自身免疫性脑脊髓炎或EAE的自身免疫性疾病模型中，MAP3K8-敲除小鼠的严重程度降低了。 我们进一步确定，与TPL2（+/+）对照组相比，OVA免疫的TPL2（ - / - ）小鼠表达高水平的IgE，并产生更严重的支气管肺泡炎症。来自免疫TPL2（ - / - ）小鼠的OVA刺激的脾细胞的支气管肺泡和上清液表达IL-4和IL-5的水平升高，这表明TPL2消融促进了T细胞反应的TH2极化。抗CD3刺激野生型和TPL2基因敲除小鼠的CD4（+）T细胞表明，TPL2消融会导致细胞自主T细胞缺陷，这主要是造成T细胞对Ag的Th2极化的造成的。通过解决TPL2（+/+）/OT2或TPL2（ - / - ）/OT2小鼠和Dendritic细胞中CD4（+）T细胞的Th1和Th2细胞因子的表达的实验，进一步支持了这一观察结果。来自TPL2（+/+）或TPL2（ - / - ）小鼠。进一步的研究表明，Th1细胞表达的TPL2水平明显高于Th2细胞。结果，TPL2（ - / - ）Th1细胞比Th2细胞表现出ERK激活的缺陷，并且表达低水平的T-bet。鉴于Th1和Th2细胞的发展取决于来自T细胞的正反馈信号本身，TPL2（ - / - ）Th1细胞的功能缺陷为TPL2中T细胞自主TH2极化提供了机械解释（ - / - ）老鼠。 我们还研究了MAP3K8在先天免疫细胞中的作用。 为了解决这个问题，我们用模型病原体单核细胞增生剂感染了TPL2（ - / - ）小鼠。我们发现TPL2（ - / - ）小鼠感染了I.V.与野生型小鼠相比，单核细胞增生李斯特氏菌具有增加的病原体负担，并迅速屈服于感染。增强的易感性与通过TLR2和核苷酸结合寡聚结构域2的信号传导相关，这是先前显示的两个受体介导李斯特菌识别的受体。令人惊讶的是，即使TPL2与TNF的调节有关，TNF的产生也没有显着损害。我们发现，TPL2的作用在调节TNF中具有细胞类型的特异性效应，并从某些但不是全部的模式识别受体（PRR）传递信号。与TNF的细胞类型和受体特异性调节相反，我们发现TPL2对于巨噬细胞和树突状细胞的IL-1Beta产生至关重要。这些研究暗示TPL2是与危险相关的分子模式的模式识别受体的协作，以诱导TNF和IL-1BETA产生和最佳宿主防御。