Lipopolysaccharide (LPS) partial structures inhibit responses to LPS in a human macrophage cell line without inhibiting LPS uptake by a CD14-mediated pathway.
Lipopolysaccharide (LPS) partial structures inhibit responses to LPS in a human macrophage cell line without inhibiting LPS uptake by a CD14-mediated pathway.
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DOI：
10.1084/jem.176.2.485
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发表时间：
1992-08-01
期刊：
影响因子：
--
通讯作者：
Munford RS
中科院分区：
文献类型：
--
作者：
Kitchens RL;Ulevitch RJ;Munford RS
缺乏酰氧基酰基的脂多糖 (LPS) 可以拮抗人体细胞对 LPS 的反应。尽管抑制位点和机制尚不清楚，但有人提出这些抑制分子与 LPS 竞争共同的细胞靶标，例如细胞表面结合受体。在本研究中，我们使用体外模型系统来检验这一假设并评估 CD14 在细胞对 LPS 反应中的作用。将 THP-1 人单核巨噬细胞系的细胞暴露于 1,25 二羟基维生素 D3，以诱导对塑料的粘附和 CD14 的表达，CD14 是与 LPS 结合蛋白 (LBP) 复合的 LPS 结合受体。通过将细胞暴露于放射性标记的配体较短的孵育时间来测量皮克[3H]LPS（激动剂）和酶促脱酰化LPS[3H]dLPS（拮抗剂）的摄取。然后通过测量核 NF-κ B 结合活性的诱导和细胞相关白细胞介素 (IL)-1 β 的产生，将细胞相关 LPS 和 dLPS 的量与细胞反应相关联。我们发现细胞吸收了相似量的[3H]LPS或[3H]dLPS。 LBP 大大提高了配体的细胞积累速率，并被 CD14 单克隆抗体 (mAb 60b) 阻断，但 dLPS 或 dLPS-LBP 复合物未诱导细胞反应。相反，LPS 刺激 NF-κ B 结合活性和 IL-1 β 显着增加。 LBP 增强了这些反应，mAb 60b 抑制了这些反应。 dLPS 及其合成脂质 A 对应物 LA-14-PP（也称为脂质 Ia、脂质 IVa 或化合物 406）强烈抑制 LPS 诱导的 NF-κ B 和 IL-1 β，但两种拮抗剂均不抑制通过 CD14 对 LPS 的摄取。 dLPS 不会抑制 NF-κ B 对肿瘤坏死因子 (TNF) α 或佛波酯的反应。我们的结果表明 (a) 在 LBP 存在的情况下，刺激性和非刺激性配体都可以与 CD14 结合； (b) dLPS 的抑制机制是 LPS 特异性的，但不涉及阻断 LPS 与 CD14 的结合； (c) 与其他人之前的结果一致，在没有可检测到的 CD14 结合的情况下，高浓度的 LPS 可以刺激细胞。研究结果表明，在 THP-1 细胞中，dLPS 抑制位点位于 LPS 信号通路中 CD14 结合的远端，这表明 CD14 以外的分子在 LPS 信号传导中也很重要。
Lipopolysaccharides (LPS) that lack acyloxyacyl groups can antagonize responses to LPS in human cells. Although the site and mechanism of inhibition are not known, it has been proposed that these inhibitory molecules compete with LPS for a common cellular target such as a cell- surface binding receptor. In the present study, we used an in vitro model system to test this hypothesis and to evaluate the role of CD14 in cellular responses to LPS. Cells of the THP-1 human monocyte- macrophage cell line were exposed to 1,25 dihydroxyvitamin D3 to induce adherence to plastic and expression of CD14, a binding receptor for LPS complexed with LPS-binding protein (LBP). The uptake of picograms of [3H]LPS (agonist) and enzymatically deacylated LPS [3H]dLPS (antagonist) was measured by exposing the cells to the radiolabeled ligands for short incubation periods. The amounts of cell-associated LPS and dLPS were then correlated with cellular responses by measuring the induction of nuclear NF-kappa B binding activity and the production of cell-associated interleukin (IL)-1 beta. We found that similar amounts of [3H]LPS or [3H]dLPS were taken up by the cells. The rate of cellular accumulation of the ligands was greatly enhanced by LBP and blocked by a monoclonal antibody to CD14 (mAb 60b), yet no cellular responses were induced by dLPS or dLPS-LBP complexes. In contrast, LPS stimulated marked increases of NF-kappa B binding activity and IL-1 beta. These responses were enhanced by LBP and inhibited by mAb 60b. dLPS and its synthetic lipid A counterpart, LA-14-PP (also known as lipid Ia, lipid IVa, or compound 406) strongly inhibited LPS-induced NF- kappa B and IL-1 beta, yet neither antagonist inhibited the uptake of LPS via CD14. dLPS did not inhibit NF-kappa B responses to tumor necrosis factor (TNF) alpha or phorbol ester. Our results indicate that (a) both stimulatory and nonstimulatory ligands can bind to CD14 in the presence of LBP; (b) the mechanism of inhibition by dLPS is LPS- specific, yet does not involve blockade of LPS binding to CD14; and (c) in keeping with previous results of others, large concentrations of LPS can stimulate the cells in the absence of detectable binding to CD14. The findings indicate that the site of dLPS inhibition is distal to CD14 binding in the LPS signal pathway in THP-1 cells, and suggest that molecules other than CD14 are important in LPS signaling.
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影响因子：
3.5
作者：
LUNDJOHANSEN, F;OLWEUS, J;BJERKNES, R
通讯作者：
BJERKNES, R
影响因子：
56.9
作者：
SCHUMANN, RR;LEONG, SR;ULEVITCH, RJ
通讯作者：
ULEVITCH, RJ
影响因子：
5.5
作者：
FLEIT, HB;KOBASIUK, CD
通讯作者：
KOBASIUK, CD
DOI：
10.1084/jem.175.6.1697
发表时间：
1992-06-01
期刊：
The Journal of experimental medicine
影响因子：
--
作者：
Lee JD;Kato K;Tobias PS;Kirkland TN;Ulevitch RJ
通讯作者：
Ulevitch RJ
DOI：
10.1073/pnas.86.7.2336
发表时间：
1989-04-01
影响因子：
11.1
作者：
OSBORN, L;KUNKEL, S;NABEL, GJ
通讯作者：
NABEL, GJ