Nature Immunology
2, 361 - 367 (2001)
doi:10.1038/86373
Dendritic cells express tight junction proteins and penetrate gut epithelial monolayers to sample bacteriaMaria Rescigno1, Matteo Urbano1, Barbara Valzasina1, Maura Francolini2, Gianluca Rotta1, Roberto Bonasio1, Francesca Granucci1, Jean-Pierre Kraehenbuhl3
& Paola Ricciardi-Castagnoli11
Department of Biotechnology and Bioscience, University of Milano-Bicocca, Milano, Italy. 2
CNR, Cellular and Molecular Pharmacology Centre, Milano, Italy. 3
Swiss Institute for Experimental Cancer Research, University of Lausanne, Epalinges, Switzerland.
Correspondence should be addressed to Paola Ricciardi-Castagnoli paola.castagnoli@unimib.itPenetration of the gut mucosa by pathogens expressing invasion genes is believed to occur mainly through specialized epithelial cells, called M cells, that are located in Peyer's patches. However, Salmonella typhimurium that are deficient in invasion genes encoded by Salmonella pathogenicity island 1 (SPI1) are still able to reach the spleen after oral administration. This suggests the existence of an alternative route for bacterial invasion, one that is independent of M cells. We report here a new mechanism for bacterial uptake in the mucosa tissues that is mediated by dendritic cells (DCs). DCs open the tight junctions between epithelial cells, send dendrites outside the epithelium and directly sample bacteria. In addition, because DCs express tight-junction proteins such as occludin, claudin 1 and zonula occludens 1, the integrity of the epithelial barrier is preserved.
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