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

细菌内毒素对人单核细胞的刺激作用 脂多糖，诱导多种细胞因子的表达， 包括肿瘤坏死因子-a、白介素1b、白介素6和白介素10。IL-10表达延迟 相对于TNF-a、IL-1b和IL-6的水平。此外，IL-10的反馈 抑制肿瘤坏死因子-a、白介素1b和白介素6的表达，从而提供一种有效的 控制促炎细胞因子产生的自分泌机制 在单核细胞中。Th1型淋巴因子--干扰素-g显著上调肿瘤坏死因子-a 在单核细胞中产生。然而，干扰素-g的确切机制 调节这一效应的机制尚不清楚。我们检测了干扰素-g对小鼠血管内皮细胞生长的影响。 内毒素刺激单核细胞IL-10的表达及其相互关系 IL-10和肿瘤坏死因子-a在这些细胞中的产生之间。内毒素刺激 诱导多种细胞因子的快速、有序表达。稳态 肿瘤坏死因子-α的mRNA水平迅速升高，在2-3天达到最高水平 心率在刺激后急剧下降。IL-1b和IL-6mRNA 在内毒素刺激后，水平也显著上升，但 下降速度慢于肿瘤坏死因子-α。下调肿瘤坏死因子-α的基因表达， IL-1b和IL-6与血浆中IL-1b和IL-6呈延迟性和渐进性升高相吻合 IL-10基因表达水平。此外，IL-10与抗IL-10的中和 抗体可延长肿瘤坏死因子-αmRNA的表达，并显著增加 净肿瘤坏死因子-α产量。干扰素-g抑制IL-10mRNA和IL-10mRNA的表达 蛋白质以剂量依赖的方式。此外，对IL-10的抑制 产量与震级和地震强度的显著增长相关 肿瘤坏死因子-α表达持续时间。因此，通过增强肿瘤坏死因子-α的产生 单核细胞中干扰素-g与内源性IL-10的抑制有关 表情。这些发现最近被记录在一篇发表在 免疫学杂志(唐纳利等人)1995年。J.免疫。 155：1420-1427)。在未来的实验中，我们将尝试定义 IL-10下调细胞因子产生的机制，特别是 活化的单核细胞中的肿瘤坏死因子-α。在这方面，我们还将研究 这种IL-10诱导效应的组织特异性。在预赛中 实验发现，尽管IL-10明显抑制 单核细胞产生肿瘤坏死因子-α，但不抑制肿瘤坏死因子-α的表达 在激活的CD3+T细胞中。因此，IL-10的抑制作用可能是 可在单核细胞中诱导，但不能在淋巴细胞中诱导。这些研究的结果 相关的研究将提高我们对生物行为的认识 从而提高我们调节这种细胞因子的能力 治疗某些炎症性疾病的潜在治疗剂 疾病。

Stimulation of human monocytes with bacterial endotoxin, lipopolysaccharide (LPS), induces expression of multiple cytokines, including TNF-a, IL-1b, IL-6 and IL-10. IL-10 expression is delayed relative to that of TNF-a, IL-1b and IL-6. Furthermore, IL-10 feedback inhibits expression of TNF-a, IL-1b and IL-6, thus providing an efficient autocrine mechanism for controlling proinflammatory cytokine production in monocytes. The Th1-type lymphokine, IFN-g, markedly upregulates TNF-a production in monocytes. However, the precise mechanism by which IFN-g mediates this effect is unknown. We examined the effects of IFN-g on IL-10 expression in LPS-stimulated monocytes, and the relationship between IL-10 and TNF-a production in these cells. LPS stimulation induced rapid, ordered expression of multiple cytokines. Steady-state mRNA levels for TNF-a increased rapidly, reached maximal levels by 2-3 hr post stimulation, and then declined sharply. IL-1b and IL-6 mRNA levels also increased markedly following stimulation with LPS, but decreased more slowly than TNF-a. Downregulation of mRNA for TNF-a, IL-1b and IL-6 coincided with a delayed and more gradual increase in IL-10 mRNA levels. Furthermore, neutralization of IL-10 with anti-IL-10 antibodies prolonged TNF-a mRNA expression, and significantly increased net TNF-a production. IFN-g suppressed expression of IL-10 mRNA and protein in a dose-dependent manner. Moreover, inhibition of IL-10 production correlated with a marked increase in both the magnitude and duration of TNF-a expression. Thus, potentiation of TNF-a production by IFN-g in monocytes is coupled to inhibition of endogenous IL-10 expression. These findings were recently documented in a paper in the Journal of Immunology (Donnelly et al. 1995. J. Immunol. 155:1420-1427). In future experiments, we will attempt to define the mechanism by which IL-10 downregulates cytokine production, particularly TNF-a, in activated monocytes. In this context, we will also examine the tissue specificity of this IL-10-induced effect. In preliminary experiments, we have found that although IL-10 markedly inhibits production of TNF-a in monocytes, it does not inhibit expression of TNF-a in activated CD3+ T cells. Thus, the inhibitory action of IL-10 may be inducible in monocytic but not lymphocytic cells. The results of these and related studies will enhance our knowledge of the biological actions of IL-10, and thereby improve our ability to regulate this cytokine as a potential therapeutic agent for the treatment of certain inflammatory diseases.