Binding, internalization, and deacylation of bacterial lipopolysaccharide by human neutrophils.
Binding, internalization, and deacylation of bacterial lipopolysaccharide by human neutrophils.
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DOI：
10.4049/jimmunol.151.2.959
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发表时间：
1993-07
影响因子：
4.4
通讯作者：
M. Luchi;R. Munford
中科院分区：
文献类型：
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作者：
M. Luchi;R. Munford
细菌 LPS 是启动和刺激中性粒细胞 (PMN) 的有效激动剂。尽管最近人们对这些细胞和其他细胞上的 LPS 结合受体了解很多，但对于与细胞表面结合的 LPS 随后的命运却知之甚少。在这些研究中，我们评估了大肠杆菌 [3H]LPS 与人 PMN 相互作用的三个事件：1) 与质膜结合； 2) 易位至细胞内区室； 3)酶法脱酰。我们的结果表明，PMN 至少通过两种机制结合 LPS：当存在血清时，LPS 几乎完全与 CD14 结合，而在不存在血清时，其他结合机制占主导地位。因此，血清增强了 CD14 介导的 LPS 结合，尽管当添加血清时，细胞相关 LPS 的总量平均仅增加两倍。结合速度超过了 LPS 的细胞内运动，但至少 1%/min 的细胞相关 LPS 易位至细胞内区室。在没有血清的情况下，LPS 内化在存在可阻断 LPS-CD14 结合的 mAb 的情况下发生，这表明与 CD14 的相互作用对于 LPS 穿过质膜并不重要。 LPS 脱酰作用会在几个小时内发生，并受到减少溶酶体（内体）酸化的药物的抑制。这一发现与酰氧基酰基水解酶的脱酰作用一致，酰氧基酰基水解酶具有酸性pH最佳值，并且表明LPS至少短暂地移动到酸性细胞内区室中。这些实验为评估 LPS-中性粒细胞相互作用提供了一个新的时间框架。
Bacterial LPS is a potent agonist for priming and stimulating neutrophils (PMN). Although much has recently been learned about the binding receptors for LPS on these and other cells, little is known about the subsequent fate of LPS that has bound to the cell surface. In these studies, we evaluated three events in the interaction of Escherichia coli [3H]LPS with human PMN: 1) binding to the plasma membrane; 2) translocation to an intracellular compartment; and 3) enzymatic deacylation. Our results suggest that PMN bind LPS by at least two mechanisms: when serum is present, LPS binds almost entirely to CD14, whereas in the absence of serum, other binding mechanisms predominate. Serum thus augments CD14-mediated LPS binding, although the total amount of cell-associated LPS increases only by a factor of two, on average, when serum is added. Binding outpaces intracellular movement of the LPS, yet at least 1%/min of the cell-associated LPS is translocated to an intracellular compartment. In the absence of serum, LPS internalization occurs in the presence of a mAb that blocks LPS-CD14 binding, suggesting that an interaction with CD14 is not essential for LPS to traffic beyond the plasma membrane. LPS deacylation, which occurs over several hours, is inhibited by agents that reduce lysosomal (endosomal) acidification. This finding is consistent with a deacylating role for acyloxyacyl hydrolase, which has an acid pH optimum, and suggests that LPS moves at least transiently into an acidic intracellular compartment. These experiments provide a new temporal framework for evaluating LPS-neutrophil interactions.