Cunningham M D, Seachord C, Ratcliffe K, Bainbridge B, Aruffo A, Darveau R P
Bristol-Myers Squibb Pharmaceutical Research Institute, Seattle, Washington 98121, USA.
Infect Immun. 1996 Sep;64(9):3601-8. doi: 10.1128/iai.64.9.3601-3608.1996.
Helicobacter pylori and Porphyromonas gingivalis are gram-negative bacteria associated with chronic inflammatory diseases. These bacteria possess lipopolysaccharides (LPSs) that are able to activate human monocytes to produce tumor necrosis factor alpha but fail to activate human endothelial cells to express E-selectin. With Escherichia coli LPS, tumor necrosis factor alpha activation requires membrane-bound CD14 and E-selectin expression requires soluble CD14 (sCD14). Therefore, the ability of H. pylori and P. gingivalis LPSs to transfer to and bind sCD14 was examined by using immobilized recombinant sCD14 and human serum or recombinant LPS-binding protein (LBP). H. pylori and P. gingivalis LPSs were transferred to sCD14 when serum or LBP was present. However, the transfer of these LPSs to CD14 in serum was significantly slower than the transfer of E. coli LPS. Quantitation of the transfer rates by Michaelis-Menten kinetics yielded K(m) values of 6 and 0.1 nM for H. pylori and E. coli LPSs, respectively. The amount of P. gingivalis LPS required to obtain half-maximum binding to CD14 was approximately 10-fold greater than the amount of E. coli LPS required. The slower transfer rates displayed by these LPSs can be explained by the poor binding to LBP observed in direct binding assays. These results are consistent with the proportionately lower ability of these LPSs to activate monocytes compared with E. coli LPS. However, the ability of H. pylori and P. gingivalis LPSs to bind LBP and transfer to sCD14 demonstrates that the lack of endothelial cell CD14-dependent cell activation by these LPSs occurs distal to sCD14 binding.
幽门螺杆菌和牙龈卟啉单胞菌是与慢性炎症性疾病相关的革兰氏阴性菌。这些细菌拥有脂多糖（LPS），能够激活人类单核细胞产生肿瘤坏死因子α，但无法激活人类内皮细胞表达E选择素。对于大肠杆菌LPS，肿瘤坏死因子α的激活需要膜结合型CD14，而E选择素的表达需要可溶性CD14（sCD14）。因此，通过使用固定化重组sCD14和人血清或重组LPS结合蛋白（LBP），检测了幽门螺杆菌和牙龈卟啉单胞菌LPS转移至sCD14并与之结合的能力。当存在血清或LBP时，幽门螺杆菌和牙龈卟啉单胞菌LPS会转移至sCD14。然而，这些LPS在血清中转移至CD14的速度明显慢于大肠杆菌LPS。通过米氏动力学对转移速率进行定量分析，得出幽门螺杆菌和大肠杆菌LPS的K(m)值分别为6和0.1 nM。获得与CD14半最大结合所需的牙龈卟啉单胞菌LPS量比所需的大肠杆菌LPS量大约高10倍。这些LPS显示出较慢的转移速率，这可以通过直接结合试验中观察到的与LBP结合不佳来解释。这些结果与这些LPS与大肠杆菌LPS相比激活单核细胞的能力成比例较低是一致的。然而，幽门螺杆菌和牙龈卟啉单胞菌LPS结合LBP并转移至sCD14的能力表明，这些LPS缺乏内皮细胞CD14依赖性细胞激活发生在sCD14结合的下游。
