Salh B, Hoeflick K, Kwan W, Pelech S
Department of Medicine, University of British Columbia, Vancouver, BC, Canada.
Immunology. 1998 Nov;95(3):473-9. doi: 10.1046/j.1365-2567.1998.00614.x.
Monocytic cells have been shown to produce endothelin, a potent vasoconstrictor molecule with immune modulating properties. The signalling mechanisms involved in this response are presently unclear. Monocytes are also believed to play an important role in inflammatory bowel disease (IBD). The objective of this study was to characterize the role of various cytokines, bacterial lipopolysaccharide (LPS) and colony-stimulating factors on the production of endothelin (ET) by freshly isolated human monocytes. Compelling circumstantial evidence exists for the conditions being investigated occurring in inflamed bowel mucosa to where monocytes migrate. Whereas LPS stimulated the release of 7 pg ET/2x106 cells in 40 hr, interferon-gamma (IFN-gamma) stimulated 45 pg ET/2x106 cells in 40 hr. There was an additive response when the two stimuli were employed together. Significantly the addition of either granulocyte-macrophage colony-stimulating factor (GM-CSF) or interleukin-3 (IL-3) effected a two- to threefold, dose-dependent increase in the production of ET. Production of endothelin was reproducibly blocked by the addition of the protein kinase C (PKC) inhibitors staurosporine and H7, as well as by the protein synthesis inhibitor cycloheximide. Assessment of the activities of the alpha and beta isoforms of conventional protein kinase C (PKC), as determined by MonoQ column fractionated calcium and lipid activatible phosphotransferase activity towards myelin basic protein (MBP) revealed an additive effect of using LPS, IFN-gamma and GM-CSF, which was even greater than that demonstrated for phorbol myristate acetate (PMA). Additionally the secretion of ET by monocytes from Crohn's disease patients (in remission) was analysed and compared with an age-matched control group. There was no significant difference between the two. These results: (1) demonstrate an important synergistic role for GM-CSF and IL-3 in the predominantly IFN-gamma-mediated ET production by normal human monocytes; (2) indicate a possible role for the protein kinase C signalling pathway in this response; and (3) argue against a primary abnormality of ET production in peripheral monocytes from patients with Crohn's disease.
单核细胞已被证明能产生内皮素，这是一种具有免疫调节特性的强效血管收缩分子。目前尚不清楚参与这种反应的信号传导机制。单核细胞也被认为在炎症性肠病（IBD）中起重要作用。本研究的目的是确定各种细胞因子、细菌脂多糖（LPS）和集落刺激因子对新鲜分离的人单核细胞产生内皮素（ET）的作用。有令人信服的间接证据表明，所研究的条件发生在单核细胞迁移到的炎症性肠黏膜中。LPS在40小时内刺激释放7 pg ET/2×10⁶个细胞，而干扰素-γ（IFN-γ）在40小时内刺激释放45 pg ET/2×10⁶个细胞。当两种刺激一起使用时，有相加反应。值得注意的是，添加粒细胞-巨噬细胞集落刺激因子（GM-CSF）或白细胞介素-3（IL-3）会使ET的产生呈两到三倍的剂量依赖性增加。添加蛋白激酶C（PKC）抑制剂星形孢菌素和H7以及蛋白质合成抑制剂环己酰亚胺可重复性地阻断内皮素的产生。通过MonoQ柱分级分离钙和脂质激活的对髓鞘碱性蛋白（MBP）的磷酸转移酶活性来评估传统蛋白激酶C（PKC）的α和β同工型的活性，结果显示使用LPS、IFN-γ和GM-CSF有相加作用，甚至比佛波酯肉豆蔻酸酯（PMA）所显示的作用更大。此外，分析并比较了克罗恩病患者（缓解期）单核细胞分泌ET的情况与年龄匹配的对照组。两者之间没有显著差异。这些结果：（1）证明了GM-CSF和IL-3在正常人单核细胞主要由IFN-γ介导的ET产生中起重要的协同作用；（2）表明蛋白激酶C信号通路在这种反应中可能起作用；（3）反对克罗恩病患者外周单核细胞中ET产生存在原发性异常的观点。
