hPepT1-mediated epithelial transport of bacteria-derived chemotactic peptides enhances neutrophil-epithelial interactions
hPepT1-mediated epithelial transport of bacteria-derived chemotactic peptides enhances neutrophil-epithelial interactions
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DOI：
10.1172/jci4179
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发表时间：
1998-12-01
影响因子：
15.9
通讯作者：
Madara, JL
中科院分区：
文献类型：
--
作者：
Merlin, D;Steel, A;Madara, JL
肠上皮细胞表达 hPepT1，这是一种负责吸收多种小肽的顶端转运蛋白。由于这些可能包含 n-甲酰化肽，我们检查了 hPepT1 是否可以转运模型 n-甲酰化肽 fMLP，如果可以，则检查 fMLP 的细胞摄取是否影响中性粒细胞-上皮相互作用。 hPepT1 表达增强了卵母细胞对 fMLP 的摄取。此外，fMLP 竞争性抑制表达 hPepT1 的卵母细胞对已知 hPepT1 底物（甘氨酰肌氨酸）的摄取。在已知表达这种转运蛋白的极化人肠上皮细胞系 (Caco2-BBE) 中进一步检查了 hPepT1 肽的摄取，上皮单层内化顶端 fMLP 的方式受到其他 hPepT1 识别的溶质的竞争性抑制，但不受 hPepT1 不转运的相关溶质的竞争性抑制。细胞内 pH 值的荧光分析表明，fMLP 摄取伴随着胞质酸化，这与 hPepT1 作为肽 H+ 协同转运蛋白的已知功能一致，腔内 fMLP 导致中性粒细胞跨上皮单层定向运动。抑制 hPepT1 介导的 fMLP 转运的溶质可将中性粒细胞迁移减少约 50%。相反，提高 hPepT1 介导的 fMLP 摄取率（胞质酸化）的条件可使中性粒细胞跨上皮迁移增强约 70%。我们得出结论，hPepT1 转运 fMLP，并且这些肽的摄取影响中性粒细胞-上皮相互作用。这些数据（a）强调了 hPepT1 在介导肠道炎症中的重要性，（b）提出了调节 hPepT1 活性可能影响肠道炎症状态的可能性，以及（c）提供了主动跨上皮转运与中性粒细胞-上皮相互作用之间联系的第一个证据。
Intestinal epithelial cells express hPepT1, an apical transporter responsible for the uptake of a broad array of small peptides. As these could conceivably include n-formyl peptides, we examined whether hPepT1 could transport the model n-formylated peptide fMLP and, if so, whether such cellular uptake of fMLP influenced neutrophil-epithelial interactions. fMLP uptake into oocytes was enhanced by hPepT1 expression. In addition, fMLP competitively inhibited uptake of a known hPepT1 substrate (glycylsarcosine) in hPepT1 expressing oocytes. hPepT1 peptide uptake was further examined in a polarized human intestinal epithelial cell line (Caco2-BBE) known to express this transporter, Epithelial monolayers internalized apical fMLP in a fashion that was competitively inhibited by other hPepT1 recognized solutes, but not by related solutes that were not transported by hPepT1. Fluorescence analyses of intracellular pH revealed that fMLP uptake was accompanied by cytosolic acidification, consistent with the known function of hPepT1 as a peptide H+ cotransporter, Lumenal fMLP resulted in directed movement of neutrophils across epithelial monolayers. Solutes that inhibit hPepT1-mediated fMLP transport decreased neutrophil transmigration by similar to 50%. Conversely, conditions that enhanced the rate of hPepT1-mediated fMLP uptake (cytosolic acidification) enhanced neutrophil-transepithelial migration by similar to 70%. We conclude that hPepT1 transports fMLP and uptake of these peptide influences neutrophil-epithelial interactions. These data (a) emphasize the importance of hPepT1 in mediating intestinal inflammation, (b) raise the possibility that modulating hPepT1 activity could influence states of intestinal inflammation, and (c) provide the first evidence of a link between active transepithelial transport and neutrophil-epithelial interactions.