Effect of hypoxia on release of IL-1 and TNF by human alveolar macrophages
Effect of hypoxia on release of IL-1 and TNF by human alveolar macrophages
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DOI：
10.1165/ajrcmb.14.2.8630267
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发表时间：
1996-02-01
影响因子：
6.4
通讯作者：
Hunninghake, GW
中科院分区：
文献类型：
--
作者：
Hempel, SL;Monick, MM;Hunninghake, GW
我们以前的工作证明，在暴露于脂多糖（LPS）期间，缺氧降低人前列腺素H合酶-2（PGHS-2）基因的转录，导致前列腺素E（2）（PGE（2））合成降低（J. Biol. Chem. 269：32979 - 32984，1994）。因为据报道PGE（2）可抑制白细胞介素1（IL-1）和肿瘤坏死因子（TNF），所以低氧可能通过PGE（2）的变化改变人肺泡巨噬细胞释放IL-1和TNF。此外，与PGHS-2一样，TNF和IL-1启动子含有可能被缺氧改变的氧化剂敏感元件。因此，我们假设LPS诱导的TNF和IL-1释放将被缺氧改变。人肺泡巨噬细胞与0至1 μ g/ml LPS在具有5%CO2的室内空气培养箱或连续灌注5%CO2的低氧培养箱中培养24小时CO2/95%N-2（O-2 <0.05%）。在室内空气中，LPS以剂量依赖性方式增加IL-1 β mRNA和增加IL-1 β蛋白释放到培养基中。低氧增加了LPS刺激的IL-1 β释放30%以上的室内空气控制。然而，免疫印迹显示，与室内空气对照相比，缺氧不会引起细胞内IL-1 β的变化。LPS诱导的IL-1 β信息在缺氧时也没有变化。低氧可明显降低IL-1抑制因子IL-1RA的表达，但无统计学意义。LPS暴露后TNF-α mRNA和蛋白质的释放也增加，低氧可显著增加LPS诱导的TNF-α信息和TNF-α的释放。与我们之前的观察结果一致，缺氧减少了LPS诱导的PGHS-2信息和蛋白，以及PGHS-2产物PGE（2）。由于PGE（2）被报道抑制IL-1和TNF基因的表达，我们在室内空气中培养期间用吲哚美辛抑制PGE（2）的合成;结果是IL-1和TNF的释放增加。在另外的研究中，加入PGE（2）抑制缺氧细胞释放TNF，使其接近室内空气对照组。总之，缺氧增加了细胞因子IL-1 β和TNF-α的释放。这可能是由于缺氧时PGE（2）合成减少所致。这些结果表明人肺泡巨噬细胞对缺氧的反应是复杂的。缺氧增加了LPS刺激的炎性细胞因子IL-1和TNF的释放，而产生抗炎前列腺素PGE（2）的PGHS-2的合成减少。
Our previous work demonstrated that hypoxia decreases transcription of the human prostaglandin H synthase-2 (PGHS-2) gene during exposure to lipopolysaccharide (LPS), resulting in decreased prostaglandin E(2) (PGE(2)) synthesis (J. Biol. Chem. 269:32979-32984, 1994). Because PGE(2) is reported to inhibit interleukin 1 (IL-1) and tumor necrosis factor (TNF), it is likely that hypoxia, through changes in PGE(2), will alter IL-1 and TNF release from the human alveolar macrophage. In addition, like PGHS-2, the TNF and IL-1 promoters contain oxidant-sensitive elements which might be altered by hypoxia, Therefore, we hypothesized that LPS-induced release of TNF and IL-1 would be altered by hypoxia, To test this, human alveolar macrophages were cultured for 24 h with 0 to 1 mu g/ml LPS in a room-air incubator with 5% CO2 or a hypoxia incubator continuously perfused with 5% CO2/95% N-2 (O-2 < 0.05%). With room air, LPS increased IL-1 beta mRNA and increased IL-1 beta protein release into the culture medium in a dose-dependent manner. Hypoxia increased the LPS-stimulated release of IL-1 beta 30% above that of room-air controls. However, immunoblots showed that hypoxia caused no change in intracellular IL-1 beta compared with room-air controls. There was also no change in LPS-induced IL-1 beta message with hypoxia. The inhibitor of IL-1, IL-1RA, was apparently decreased by hypoxia, but this decrease was not statistically significant, TNF-alpha mRNA and release of protein also increased during LPS exposure in room air, Hypoxia markedly increased LPS-induced TNF-alpha message and release of TNF-alpha compared with LPS-exposed room-air controls. Consistent with our prior observations, hypoxia decreased LPS-induced PGHS-2 message and protein, and also the PGHS-2 product, PGE(2). Because PGE(2) is reported to inhibit the expression of IL-1 and TNF genes, we inhibited PGE(2) synthesis with indomethacin during culture in room air; the result was an increase in the release of IL-1 and TNF. In additional studies, adding PGE(2) inhibited TNF release from the hypoxia cells to values near those of room-air controls. In summary, hypoxia increases the release of the cytokines IL-1 beta and TNF-alpha. This increase may be due to decreased PGE(2) synthesis during hypoxia, These results demonstrate that the response of the human alveolar macrophage to hypoxia is complex. Hypoxia increases the LPS-stimulated release of the inflammatory cytokines IL-1 and TNF, whereas synthesis of PGHS-2, which generates the anti-inflammatory prostaglandin PGE(2) is decreased.