Bastos Karina R B, Barboza Renato, Sardinha Luiz, Russo Momtchilo, Alvarez José M, Lima Maria Regina D'Império
Department of Immunology, Institute of Biomedical Sciences, University of São Paulo, Av. Prof. Lineu Prestes 1730, São Paulo, SP, Brazil, CEP 05508-000.
J Interferon Cytokine Res. 2007 May;27(5):399-410. doi: 10.1089/jir.2007.0128.
Besides the established role of interleukin-12 (IL-12) and IL-18 on interferon-gamma (IFN-gamma) production by natural killer (NK), T, and B cells, the effects of these cytokines on macrophages are largely unknown. Here, we investigated the role of IL-12/IL-18 on nitric oxide (NO) and tumor necrosis factor-alpha (TNF-alpha) production by CD11b(+) adherent peritoneal cells, focusing on the involvement of endogenously produced IFN-gamma. C57BL/6 cells released substantial amounts of NO when stimulated with IFN-gamma or lipopolysaccharide (LPS), but failed to respond to IL-12 or IL-18 or both. However, IL-12/IL-18 pretreatment was able to program these cells to release 6-8-fold more NO and TNF-alpha in response to LPS or Trypanosoma cruzi stimulation, with NO levels directly correlating with macrophage resistance to intracellular parasite growth. Analysis of IL-12/IL-18-primed cells from mice deficient in IFN-gamma, IFNGR, and IFN regulatory factor-1 (IRF-1) revealed that these molecules were essential for LPS-induced NO release, but TNF-alpha production was IFN-gamma independent. Conversely, the myeloid differentiation factor 88 (MyD88)-dependent pathway was indispensable for IL-12/IL-18-programmed LPS-induced TNF-alpha production, but not for NO release. Contaminant T and NK cells largely modulated the IL-12/IL-18 programming of LPS-induced NO response through IFN-gamma secretion. Nevertheless, a small population of IFN-gamma(+) cells with a macrophage phenotype was also identified, particularly in the peritoneum of chronically T. cruzi-infected mice, reinforcing the notion that macrophages can be an alternative source of IFN-gamma. Taken together, our data contribute to elucidate the molecular basis of the IL-12/IL-18 autocrine pathway of macrophage activation, showing that endogenous IFN-gamma plays an important role in programming the NO response, whereas the TNF-alpha response occurs through an IFN-gamma-independent pathway.
除了白细胞介素-12（IL-12）和白细胞介素-18在自然杀伤（NK）细胞、T细胞和B细胞产生干扰素-γ（IFN-γ）方面已确定的作用外，这些细胞因子对巨噬细胞的影响在很大程度上尚不清楚。在此，我们研究了IL-12/IL-18对CD11b(+)贴壁腹膜细胞产生一氧化氮（NO）和肿瘤坏死因子-α（TNF-α）的作用，重点关注内源性产生的IFN-γ的参与情况。C57BL/6细胞在用IFN-γ或脂多糖（LPS）刺激时会释放大量NO，但对IL-12或IL-18或两者均无反应。然而，IL-12/IL-18预处理能够使这些细胞在受到LPS或克氏锥虫刺激时释放的NO和TNF-α增加6至8倍，NO水平与巨噬细胞对细胞内寄生虫生长的抗性直接相关。对来自IFN-γ、IFNGR和IFN调节因子-1（IRF-1）缺陷小鼠的IL-12/IL-18预处理细胞的分析表明，这些分子对于LPS诱导的NO释放至关重要，但TNF-α的产生不依赖于IFN-γ。相反，髓样分化因子88（MyD88）依赖性途径对于IL-12/IL-18编程的LPS诱导的TNF-α产生是必不可少的，但对NO释放并非如此。污染的T细胞和NK细胞通过IFN-γ分泌在很大程度上调节了LPS诱导的NO反应的IL-12/IL-18编程。尽管如此，还鉴定出一小部分具有巨噬细胞表型的IFN-γ(+)细胞，特别是在慢性克氏锥虫感染小鼠的腹膜中，这强化了巨噬细胞可以作为IFN-γ替代来源的观点。综上所述，我们的数据有助于阐明巨噬细胞激活的IL-12/IL-18自分泌途径的分子基础，表明内源性IFN-γ在编程NO反应中起重要作用，而TNF-α反应通过不依赖于IFN-γ的途径发生。
