title: Interaction of pathogenic bacteria with rabbit appendix M cells: bacterial motility is a key feature in vivo.
abstract: Rabbit appendix consists mainly of lymphoid follicles (LF) covered by M cells, the specialized antigen-sampling cells of the mucosal immune system, and surrounded by glandular epithelium. Until now, these M cells have been characterized morphologically and histologically by using cellular markers. Here, the adhesion and transport of pathogenic bacteria were investigated to assess the function of M cells of the appendix. We used the enteroinvasive motile Salmonella typhimurium and the rabbit enteropathogenic non-motile Escherichia coli RDEC-1, which are known to target specifically rabbit M cells of Peyer's patches (PPs). We found that S. typhimurium efficiently attached and was transported through appendix M cells in vivo. In contrast to S. typhimurium, RDEC-1 targeted M cells only ex vivo, when bacteria were allowed to have direct contact with the surface of the follicle. The difference in interaction of the two bacteria with appendix M cells led us to investigate whether this could be correlated with the lack of motility of RDEC-1. We used an aflagellate mutant of S. typhimurium and found that it had the same infection phenotype as RDEC-1. Gene complementation restored the efficiency of infection to that of S. typhimurium wild-type strain. In conclusion, we show that M cells of the appendix display features of the canonical M cells of PP, since they efficiently sample luminal pathogenic bacteria. However, due to the morphology of the appendix, motile bacteria appear to be more potent in their interactions with appendix M cells.
authors.affiliation: Laboratory of Lympho-epithelial Interactions, Department of Cell Biology and Infection, Pasteur Institute, 25-28, rue du Docteur Roux, 75724 Paris cedex 15, France. marta.marchetti@curie.fr
authors.forename: Marta
authors.initials: M
authors.lastname: Marchetti
authors.forename: Jean Claude
authors.initials: JC
authors.lastname: Sirard
authors.forename: Philippe
authors.initials: P
authors.lastname: Sansonetti
authors.forename: Eric
authors.initials: E
authors.lastname: Pringault
authors.forename: Sophie
authors.initials: S
authors.lastname: Kernéis
mesh_terms: D000818:Animals; D001065:Appendix / Q000166:cytology / Q000276:immunology* / Q000382:microbiology*; D001419:Bacteria / Q000276:immunology* / Q000472:pathogenicity*; D001422:Bacterial Adhesion; D004926:Escherichia coli / Q000276:immunology / Q000472:pathogenicity; D004927:Escherichia coli Infections / Q000276:immunology / Q000382:microbiology; D005407:Flagella / Q000235:genetics / Q000502:physiology; D017353:Gene Deletion; D005816:Genetic Complementation Test; D007150:Immunohistochemistry; D007413:Intestinal Mucosa / Q000166:cytology*; D008221:Lymphoid Tissue / Q000166:cytology / Q000382:microbiology* / Q000502:physiology / Q000648:ultrastructure; D008855:Microscopy, Electron, Scanning; D009068:Movement; D009154:Mutation; D010581:Peyer's Patches / Q000382:microbiology; D011817:Rabbits; D012481:Salmonella Infections, Animal / Q000276:immunology / Q000382:microbiology; D012486:Salmonella typhimurium / Q000276:immunology / Q000472:pathogenicity