REGULATION OF CYTOKINE PRODUCTION BY IL-10 IN ENDOTOXIN-STIMULATED MONOCYTES

用细菌内毒素刺激人单核细胞， 脂多糖（LPS），诱导多种细胞因子的表达， 包括肿瘤坏死因子-α（TNF-α）、白细胞介素-1（IL-1）、IL-6 和IL-10 IL-10的表达相对于TNF、IL-1和IL-10的表达是延迟的。 IL-6。 此外，IL-10反馈抑制TNF、IL-1和TNF-α的表达。 IL-6，从而提供了一种有效的自分泌机制， 单核细胞中的促炎细胞因子产生。 我们正在研究 IL-10下调细胞因子产生的机制 内毒素刺激的单核细胞中的TNF和IL-1。 我们也在评估 IL-10对细胞信号传导事件的影响， 单核细胞中的特异性细胞因子。 我们已经发现IL-10可以拮抗 通过多种细胞因子，包括IL-4的激活和基因表达 和IFN-γ（Dickensheets和Donnelly. 1997. 159：6226）。 我们还确定了IL-10抑制IL-4诱导的IL-10表达的能力。 基因表达是酪氨酸磷酸化减少的结果 以及IL-4诱导型转录因子的核转位， STAT6。 在未来的研究中，我们将研究细胞类型特异性， 通过评估IL-10对基因表达的影响， 在多种造血和非造血细胞中表达 类型 为了进一步确定IL-10对单核细胞功能的作用， 活性，我们正在评估这种细胞因子对合成的影响， 和可溶性细胞因子受体的释放，包括I型和 II型IL-1受体（IL-1 RI和IL-1 RII）和1型和2型TNF 单核细胞的受体。 TNF-受体在刺激后从单核细胞脱落 通过LPS，并可以作为TNF拮抗剂，通过竞争与 膜相关的TNF-R用于可用的TNF。 我们发现 IFN-γ（IFN-g）下调膜TNF-R2和TNF-R3的表达。 LPS刺激的单核细胞的可溶性TNF-R2（sTNF-R2）（Dickensheets et al. 1997. Blood 90：4162）。 培养物中sTNF-R2的产生减少 IFN-γ处理的单核细胞的水平与IFN-γ处理的单核细胞的水平降低直接相关。 TNF-α mRNA的表达与TNF-α mRNA的表达呈负相关。 与此相反， IL-10上调sTNF-R2的产生并显著抑制其产生 TNF-a。 IL-10还逆转IFN-g抑制IL-10表达的能力。 sTNF-R2的产生和增强TNF-α的产生。 这些 研究结果表明，IL-10协同下调 TNF-α（一种TNF-受体激动剂），并上调sTNF-R2（a TNF-R拮抗剂）。 他们还提供了另一个例子， IL-10可以拮抗单核细胞中的马槟榔诱导的反应。 IL-10是 目前正在测试作为一种潜在的治疗剂， 一些炎症性疾病，包括类风湿性关节炎和 克罗恩病 我们的研究成果将增加我们的知识 IL-10的生物学作用，从而提高我们的能力， 规范这种生物制剂的临床使用。

Stimulation of human monocytes with bacterial endotoxin, lipopolysaccharide (LPS), induces expression of multiple cytokines, including tumor necrosis factor-alpha (TNF-a), interleukin-1 (IL-1), IL-6 and IL-10. IL-10 expression is delayed relative to that of TNF, IL-1 and IL-6. Furthermore, IL-10 feedback inhibits expression of TNF, IL-1 and IL-6, thus providing an efficient autocrine mechanism for controlling proinflammatory cytokine production in monocytes. We are examining the mechanism by which IL-10 down-regulates production of cytokines such as TNF and IL-1 in endotoxin-stimulated monocytes. We are also evaluating the effects of IL-10 on cell signaling events that are activated by specific cytokines in monocytes. We have found that IL-10 can antagonize activation and gene expression by a variety of cytokines, including IL-4 and IFN-gamma (Dickensheets and Donnelly. 1997. J. Immunol. 159:6226). We have also determined that the ability of IL-10 to inhibit IL-4-induced gene expression is a consequence of decreased tyrosine phosphorylation and nuclear translocation of the IL-4-inducible transcription factor, STAT6. In future studies, we will examine the cell type specificity of these IL-10-induced effects by evaluating the effects of IL-10 on gene expression in a variety of hematopoietic and non-hematopoietic cell types. To further define the actions of IL-10 on monocyte functional activities, we are evaluating the effects of this cytokine on synthesis and release of soluble cytokine receptors, including the type-I and type-II IL-1 receptors (IL-1RI and IL-1RII) and the type-1 and type-2 TNF receptors by monocytes. TNF-R are shed from monocytes after stimulation by LPS, and can function as TNF antagonists by competing with membrane-associated TNF-R for available TNF. We have found that IFN-gamma (IFN-g) down-regulates expression of both membrane TNF-R2 and solubleTNF-R2 (sTNF-R2) by LPS-stimulated monocytes (Dickensheets et al. 1997. Blood 90:4162). The decreased production of sTNF-R2 in cultures of IFN-g-treated monocytes correlates directly with decreased levels of TNF-R2 mRNA and inversely with the levels of TNF-a mRNA. In contrast, IL-10 up-regulates production of sTNF-R2 and markedly inhibits production of TNF-a. IL-10 also reverses the ability of IFN-g to suppress production of sTNF-R2 and to potentiate production of TNF-a. These findings demonstrate that IL-10 coordinately down-regulates production of TNF-a (a TNF-R agonist), and up-regulates production of sTNF-R2 (a TNF-R antagonist) in monocytes. They also provide another example of how IL-10 can antagonize cytokine-induced responses in monocytes. IL-10 is currently being tested as a potential therapeutic agent for the treatment of a number of inflammatory diseases, including rheumatoid arthritis and Crohn~s disease. The results of our studies will increase our knowledge of the biological actions of IL-10, and thereby improve our ability to regulate the clinical use of this biologic agent.