Keita Asa V, Gullberg Elisabet, Ericson Ann-Charlott, Salim Sa'ad Y, Wallon Conny, Kald Anders, Artursson Per, Söderholm Johan D
Department of Biomedicine and Surgery, Division of Surgery, University Hospital, Linköping, Sweden.
Lab Invest. 2006 May;86(5):504-16. doi: 10.1038/labinvest.3700397.
The follicle-associated epithelium (FAE), covering Peyer's patches, provides a route of entry for antigens and microorganisms. Animal studies showed enhanced antigen and bacterial uptake in FAE, but no study on barrier function of human FAE has been reported. Our aim was to characterize the normal barrier properties of human FAE. Specimens of normal ileum were taken from 30 patients with noninflammatory colonic disease. Villus epithelium (VE) and FAE were identified and mounted in Ussing chambers. Permeability to 51Cr-EDTA, transmucosal flux of the protein antigen, horseradish peroxidase (HRP), and transport of fluorescent Escherichia coli (chemically killed K-12 and live HB101) were measured. Uptake mechanisms were studied by confocal- and transmission electron microscopy, and by using pharmacological inhibitors in an in vitro coculture model of FAE and in human ileal FAE. HRP flux was substantially higher in FAE than in VE, and was reduced by an amiloride analog. Electron microscopy showed HRP-containing endosomes. Transport of E. coli K-12 and HB101 was also augmented in FAE and was confirmed by confocal microscopy. In vitro coculture experiments and electron microscopy revealed actin-dependent, mainly transcellular, uptake of E. coli K-12 into FAE. 51Cr-EDTA permeability was equal in FAE and VE. Augmented HRP flux and bacterial uptake but similar paracellular permeability, suggest functional variations of transcellular transport in the FAE. We show for the first time that FAE of human ileum is functionally distinct from regular VE, rendering the FAE more prone to bacterial-epithelial cell interactions and delivery of antigens to the mucosal immune system.
覆盖派尔集合淋巴结的滤泡相关上皮（FAE）为抗原和微生物提供了一条进入途径。动物研究表明，FAE对抗原和细菌的摄取增强，但尚未见关于人FAE屏障功能的研究报道。我们的目的是描述人FAE的正常屏障特性。从30例非炎性结肠疾病患者中获取正常回肠标本。识别绒毛上皮（VE）和FAE，并将其安装在尤斯灌流小室中。测量51Cr-乙二胺四乙酸的通透性、蛋白抗原的跨黏膜通量、辣根过氧化物酶（HRP）以及荧光大肠杆菌（化学灭活的K-12和活的HB101）的转运。通过共聚焦显微镜和透射电子显微镜，以及在FAE的体外共培养模型和人回肠FAE中使用药理学抑制剂来研究摄取机制。FAE中HRP通量显著高于VE，且被一种氨氯地平类似物降低。电子显微镜显示含有HRP的内体。FAE中大肠杆菌K-12和HB101的转运也增加，共聚焦显微镜证实了这一点。体外共培养实验和电子显微镜显示，大肠杆菌K-12通过肌动蛋白依赖的、主要是跨细胞的方式摄取进入FAE。FAE和VE中51Cr-乙二胺四乙酸的通透性相等。HRP通量增加和细菌摄取增加，但细胞旁通透性相似，提示FAE中跨细胞转运存在功能差异。我们首次表明，人回肠的FAE在功能上与正常VE不同，使FAE更容易发生细菌与上皮细胞的相互作用以及将抗原递送至黏膜免疫系统。
