Lipopolysaccharide binding protein expression in primary human hepatocytes and HepG2 hepatoma cells.
Lipopolysaccharide binding protein expression in primary human hepatocytes and HepG2 hepatoma cells.
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DOI：
10.1016/s0021-9258(17)37218-6
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发表时间：
1994-03
期刊：
影响因子：
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通讯作者：
Baiba J. Grube;Charles G. Cochane;Richard D. Ye;Carol E. Green;Mary E. McPhail;R. Ulevitch;Peter S. Tobias
中科院分区：
文献类型：
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作者：
Baiba J. Grube;Charles G. Cochane;Richard D. Ye;Carol E. Green;Mary E. McPhail;R. Ulevitch;Peter S. Tobias
脂多糖（LPS）结合蛋白（LBP）是一种正常血浆蛋白，是宿主对革兰氏阴性菌和LPS反应的重要急性期反应物。LBP与LPS形成高亲和力复合物，其结合至单核细胞表面蛋白CD14，以启动炎症介质的释放。我们发现人原代肝细胞合成LBP，并且该合成被白细胞介素（IL）-6上调。为了更详细地研究这种现象，我们评估了IL-6，IL-1和肿瘤坏死因子在地塞米松存在或不存在的情况下诱导HepG2细胞中LBP合成的能力。IL-6诱导LBP合成。地塞米松，IL-1和肿瘤坏死因子与IL-6联合使用时具有协同作用，但单独使用时效果最小。通过免疫沉淀35S标记的HepG2上清液中的LBP、测量稳态LBP mRNA水平以及分析LBP依赖性LPS与CD 14阳性细胞的结合来评估LBP的生物合成。用抗LBP抗体从IL-6刺激的HepG2细胞上清液中免疫沉淀35S标记的60-kDa蛋白。细胞RNA的北方印迹分析显示IL-6刺激的细胞中LBP mRNA增加。在来自用IL-6处理的HepG2细胞的上清液的存在下，表达CD14的细胞结合荧光化的LPS。这些数据提供了关于特定细胞因子和地塞米松调节HepG2细胞中LBP表达的第一信息。LBP的行为类似于1型急性时相蛋白。
Lipopolysaccharide (LPS)-binding protein (LBP) is a normal plasma protein and an acute phase reactant important for host responses to Gram-negative bacteria and LPS. LBP forms high affinity complexes with LPS which bind to CD14, a monocyte surface protein, to initiate the release of inflammatory mediators. We found that human primary hepatocytes synthesize LBP and that the synthesis is up-regulated by interleukin (IL)-6. To examine this phenomenon in more detail, we evaluated the capacity of IL-6, IL-1, and tumor necrosis factor to induce LBP synthesis in HepG2 cells in the presence or absence of dexamethasone. IL-6 induced LBP synthesis. Dexamethasone, IL-1, and tumor necrosis factor had a synergistic effect when combined with IL-6, but demonstrated minimal effect independently. LBP biosynthesis was evaluated by immunoprecipitation of 35S-labeled LBP from HepG2 supernatants, measurement of steady-state LBP mRNA levels, and analysis of LBP-dependent LPS binding to CD14 positive cells. An 35S-labeled, 60-kDa protein was immunoprecipitated with anti-LBP antibody from IL-6-stimulated HepG2 cell supernatants. Northern blot analysis of cellular RNA revealed an increase in LBP mRNA in IL-6-stimulated cells. CD14 expressing cells bound fluoresceinated LPS in the presence of supernatants from HepG2 cells treated with IL-6. These data provide the first information about specific cytokine and dexamethasone regulation of LBP expression in HepG2 cells. LBP behaves like a Type 1 acute phase protein.