Mechanism underlying inhibition of intestinal apical Cl-/OH- exchange following infection with enteropathogenic E-coli
Mechanism underlying inhibition of intestinal apical Cl-/OH- exchange following infection with enteropathogenic E-coli
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DOI：
10.1172/jci29625
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发表时间：
2007-02-01
影响因子：
15.9
通讯作者：
Dudeja, Pradeep K.
中科院分区：
文献类型：
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作者：
Gill, Ravinder K.;Borthakur, Alip;Dudeja, Pradeep K.
肠源性大肠埃希菌(EPEC)是引起婴幼儿腹泻的主要原因，但相关腹泻的病理生理学机制尚不清楚。我们利用体外和体内模型研究了腔膜Cl-/OH-交换过程在EPEC发病机制中的作用。CL-/OH-交换活性以OH-梯度驱动的Cl-36(-)吸收来测量。EPEC感染(60分钟-3小时)可抑制人肠道Caco-2和T84细胞的顶端Cl-/OH-交换活性。这种作用依赖于细菌III型分泌系统(TTSS)，并涉及分泌的效应分子ESPG和EspG2，已知这两种分子可以破坏宿主微管网络。微管解离剂秋水仙碱(100mM，3h)也能抑制氯-36-的摄取。在EPEC感染的细胞中，主要的顶端阴离子交换因子DRA(SLC26A3)的质膜表达显著降低，相应地，Cl-/OH-交换活性降低。共聚焦显微镜研究表明，EPEC感染引起DRA从根尖膜到小叶内室的显着重新分布。有趣的是，与野生型EPEC相比，感染ESPG缺陷的EPEC突变体细胞显著减轻了DRA蛋白表面表达的下降。EPEC体内感染(1天)后，小鼠结肠表面DRA蛋白也发生了明显的再分布。我们的数据表明，ESPG和EspG2在EPEC感染相关的腔膜氯转运抑制中发挥了重要作用，这是通过调节表面DRA的表达来实现的。
Enteropathogenic E. coli (EPEC) is a major cause of infantile diarrhea, but the pathophysiology underlying associated diarrhea is poorly understood. We examined the role of the luminal membrane Cl-/OH- exchange process in EPEC pathogenesis using in vitro and in vivo models. Cl-/OH- exchange activity was measured as OH- gradient-driven Cl-36(-) uptake. EPEC infection (60 minutes-3 hours) inhibited apical Cl-/OH- exchange activity in human intestinal Caco-2 and T84 cells. This effect was dependent upon the bacterial type III secretory system (TTSS) and involved secreted effector molecules EspG and EspG2, known to disrupt the host microtubular network. The microtubule-disrapting agent colchicine (100 mu M, 3 hours) also inhibited Cl-36- uptake. The plasma membrane expression of major apical anion exchanger DRA (SLC26A3) was considerably reduced in EPEC-infected cells, corresponding with decreased Cl-/OH- exchange activity. Confocal microscopic studies showed that EPEC infection caused a marked redistribution of DRA from the apical membrane to intraceflular compartments. Interestingly, infection of cells with an EPEC mutant deficient in espG significantly attenuated the decrease in surface expression of DRA protein as compared with treatment with wild-type EPEC. EPEC infection in vivo (1 day) also caused marked redistribution of surface DRA protein in the mouse colon. Our data demonstrate that EspG and EspG2 play an important role in contributing to EPEC infection-associated inhibition of luminal membrane chloride transport via modulation of surface DRA expression.