Translocation of Yersinia entrocolitica across reconstituted intestinal epithelial monolayers is triggered by Yersinia invasin binding to beta1 integrins apically expressed on M-like cells.
Yersinia enterocolitica cross the intestinal epithelium via translocation through M cells, which are located in the follicle-associated epithelium (FAE) of Peyer's patches (PP). To investigate the molecular basis of this process, studies were performed using a recently developed in vitro model, in which the enterocyte-like cell line Caco-2 and PP lymphocytes are co-cultured in order to establish FAE-like structures including M cells. Here, we demonstrate that Y. enterocolitica does not adhere significantly to the apical membrane of differentiated enterocyte-like Caco-2 cells that express binding sites for Ulex europaeus agglutinin (UEA)-1. In contrast, Y. enterocolitica adhered to, and was internalized by, cells that lacked UEA-1 binding sites and displayed a disorganized brush border. These cells were considered to be converted to M-like cells. Further analysis revealed that part of these cells expressed beta1 integrins at their apical surface and, as revealed by comparison of wild-type and mutant strains, interacted with invasin of Y. enterocolitica. Consistently, anti-beta1 integrin antibodies significantly inhibited internalization of inv-expressing yersiniae. Experiments with Yersinia mutant strains deficient in YadA or Yop secretion revealed that these virulence factors play a minor role in this process. After internalization, yersiniae were transported within LAMP-1-negative vacuoles to, and released at, the basal surface. Internalization and transport of yersiniae was inhibited by cytochalasin D, suggesting that F-actin assembly is required for this process. These results provide direct evidence that expression of beta1 integrins at the apical surface of M cells enables interaction with the invasin of Y. enterocolitica, and thereby initiates internalization and translocation of bacteria.
Schulte
R
R
Max von Pettenkofer-Institute for Hygiene and Medical Microbiology, Ludwig Maximilians-University, Munich, Germany.
Kerneis
S
S
Klinke
S
S
Bartels
H
H
Preger
S
S
Kraehenbuhl
J P
JP
Pringault
E
E
Autenrieth
I B
IB
D018829:Adhesins, Bacterial; D001422:Bacterial Adhesion; D001426:Bacterial Proteins / Q000378:metabolism*; D018938:Caco-2 Cells; D018920:Coculture Techniques; D004847:Epithelial Cells / Q000382:microbiology*; D006801:Humans; D019012:Integrin beta1 / Q000378:metabolism*; D007413:Intestinal Mucosa / Q000166:cytology / Q000382:microbiology*; D008214:Lymphocytes / Q000382:microbiology; D008854:Microscopy, Electron; D008856:Microscopy, Fluorescence; D015009:Yersinia Infections / Q000382:microbiology; D015008:Yersinia enterocolitica / Q000235:genetics / Q000472:pathogenicity* / Q000502:physiology
D018829:Adhesins, Bacterial; D001426:Bacterial Proteins; D019012:Integrin beta1; C053476:invasin, Yersinia