Enterocyte Cytoskeleton Changes Are Crucial for Enhanced Translocation of Nonpathogenic Escherichia coli across Metabolically Stressed Gut Epithelia
Enterocyte Cytoskeleton Changes Are Crucial for Enhanced Translocation of Nonpathogenic Escherichia coli across Metabolically Stressed Gut Epithelia
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DOI：
10.1128/iai.74.1.192-201.2006
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发表时间：
2006-01
影响因子：
3.1
通讯作者：
Aisha Nazli;Arthur Wang;Oren Steen;D. Prescott;Jun Lu;M. Perdue;J. Söderholm;P. Sherman;D. McKay
中科院分区：
文献类型：
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作者：
Aisha Nazli;Arthur Wang;Oren Steen;D. Prescott;Jun Lu;M. Perdue;J. Söderholm;P. Sherman;D. McKay
摘要大量数据表明，共生菌群是引发肠道炎症或炎症性疾病复发的诱因。我们已经证明，在代谢应激下，肠上皮细胞通过增加上皮细胞旁细胞通透性和细菌易位来对非致病细菌作出反应。在这里，我们评估了这些发现的结构基础。用0.1 mM的二硝基苯酚(去偶联氧化磷酸化)和非侵袭性、非致病性的大肠杆菌(HB101,106CFU)处理融合的人结肠上皮细胞系T84上皮细胞的融合滤器生长的单层，并加或不加各种药物的预处理。24小时后检测细胞凋亡率、紧密连接蛋白表达、跨上皮阻力(TER；细胞旁通透性的标志)以及细菌内化和易位。微管稳定剂(秋水仙碱)、微丝稳定剂(茉莉酸激动素)和笼状蛋白包裹的胞吞作用(氧化苯砷)均未能阻断DNP+E.coliHB101诱导的TER减少，但有效地阻止了细菌的内化和易位。无论是TER缺陷还是细菌移位增强都不是细胞凋亡增加的结果。这些数据表明，上皮细胞旁和跨细胞(即细菌内化)的渗透途径受不同的机制控制。因此，新陈代谢应激下的上皮细胞增加了它们的内吞活性，从而导致细菌的微管、微丝依赖的内化和跨细胞作用。我们推测，体内类似的事件将允许过多的未经处理的抗原和细菌进入粘膜，并可能通过激活驻留或招募的免疫细胞等方式引发炎症反应。
ABSTRACT Substantial data implicate the commensal flora as triggers for the initiation of enteric inflammation or inflammatory disease relapse. We have shown that enteric epithelia under metabolic stress respond to nonpathogenic bacteria by increases in epithelial paracellular permeability and bacterial translocation. Here we assessed the structural basis of these findings. Confluent filter-grown monolayers of the human colonic T84 epithelial cell line were treated with 0.1 mM dinitrophenol (which uncouples oxidative phosphorylation) and noninvasive, nonpathogenic Escherichia coli (strain HB101, 106 CFU) with or without pretreatment with various pharmacological agents. At 24 h later, apoptosis, tight-junction protein expression, transepithelial resistance (TER; a marker of paracellular permeability), and bacterial internalization and translocation were assessed. Treatment with stabilizers of microtubules (i.e., colchicine), microfilaments (i.e., jasplakinolide) and clathrin-coated pit endocytosis (i.e., phenylarsine oxide) all failed to block DNP+E. coli HB101-induced reductions in TER but effectively prevented bacterial internalization and translocation. Neither the TER defect nor the enhanced bacterial translocations were a consequence of increased apoptosis. These data show that epithelial paracellular and transcellular (i.e., bacterial internalization) permeation pathways are controlled by different mechanisms. Thus, epithelia under metabolic stress increase their endocytotic activity that can result in a microtubule-, microfilament-dependent internalization and transcytosis of bacteria. We speculate that similar events in vivo would allow excess unprocessed antigen and bacteria into the mucosa and could evoke an inflammatory response by, for example, the activation of resident or recruited immune cells.