Varying importance of soluble and membrane CD14 in endothelial detection of lipopolysaccharide
Varying importance of soluble and membrane CD14 in endothelial detection of lipopolysaccharide
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DOI：
10.4049/jimmunol.181.2.1446
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发表时间：
2008-07-15
影响因子：
4.4
通讯作者：
Kubes, Paul
中科院分区：
文献类型：
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作者：
Lloyd-Jones, Katie L.;Kelly, Margaret M.;Kubes, Paul
内皮细胞对内毒素的反应在白细胞的募集中起着关键作用，从而使宿主在革兰氏阴性感染中存活下来。在此，我们研究了可溶性CD14(SCD14)和膜CD14(MCD14)在低浓度内毒素(0.1 ng/ml)、中浓度内毒素(10 ng/ml)和高浓度内毒素(1000 ng/ml)诱导的内皮细胞反应中的作用。从血清和sCD14阴性血清中去除sCD14可以阻止低水平的内毒素检测和随后的反应。将重组的sCD14重新加入内皮系统，拯救了内皮细胞的反应。GPI连接的mCD14从内皮细胞中移除或用CD14单抗治疗内皮细胞可阻止对低水平内毒素的反应，即使在存在sCD14的情况下也是如此。这表明mCD14和sCD14在检测低水平内毒素中的作用是不重叠的。在中等水平的内毒素时，sCD14不是必需的，但即使在sCD14存在的情况下，阻断mCD14仍然阻止内皮细胞内毒素的检测和E-选择素的表达，这表明sCD14不能替代mCD14。在内毒素水平很高的情况下，mCD14和sCD14的缺失并不能阻断TLR4依赖的E-选择素的合成。在内皮细胞中检测到MyD88非依赖通路(存在TRIF相关的接头分子TRAM)。内皮细胞的MyD88非依赖性反应(干扰素-β)需要mCD14，即使在测试的最高剂量下也是如此。我们的结果显示了内皮细胞mCD14的重要作用，这是sCD14无法替代的。此外，我们还提供了内皮细胞中依赖mCD14的TRAM通路的证据，即使其他反应不再依赖mCD14。
The endothelial response to LPS is critical in the recruitment of leukocytes, thereby allowing the host to survive Gram-negative infection. Herein, we investigated the roles of soluble CD14 (sCD14) and membrane CD14 (mCD14) in the endothelial response to low level LPS (0.1 ng/ml), intermediate level LPS (10 ng/ml), and high level LPS (1000 ng/ml). Removal of sCD14 from serum and sCD14-negative serum prevented low level LPS detection and subsequent response. Addition of recombinant sCD14 back into the endothelial system rescued the endothelial response. GPI-linked mCD14 removal from endothelium or endothelial treatment with a CD14 mAb prevented responses to low-level LPS even in the presence of sCD14. This demonstrates essential nonoverlapping roles for both mCD14 and sCD14 in the detection of low-level LPS. At intermediate levels of LPS, sCD14 was not required, but blocking mCD14 still prevented endothelial LPS detection and E-selectin expression, even in the presence of sCD14, suggesting that sCD14 cannot substitute for mCD14. At very high levels of LPS, the absence of mCD14 and sCD14 did not abrogate TLR4-dependent, E-selectin synthesis in response to LPS. The MyD88 independent pathway was detected in endothelium (presence of TRIF-related adaptor molecule TRAM). The MyD88-independent response (IFN-beta) in endothelium required mCD14 even at the highest LPS dose tested. Our results demonstrate an essential role for endothelial mCD14 that cannot be replaced by sCD14. Furthermore, we have provided evidence for a TRAM pathway in endothelium that is dependent on mCD14 even when other responses are no longer mCD14 dependent.