Dendritic cells express tight junction proteins and penetrate gut epithelial monolayers to sample bacteria

Abstract

Penetration 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.

Dendritic cell activation and maturation induced by mucosal fluid from women with bacterial vaginosis

“…Alternatively, intraepithelial DC can directly interact with luminal pathogens via dendrites that penetrate epithelium and sample the bacteria in the lumen [55,56]. The ability of both DEC 205+ DC and pDC to extend dendrites into the vaginal lumen was recently demonstrated by LeBlanc et al in a murine model of vaginal Candida albicans infection [57].…”

“…Stimulation of DC can be mediated by microbes that cross the epithelial barrier via transport mechanisms [55]. Alternatively, intraepithelial DC can directly interact with luminal pathogens via dendrites that penetrate epithelium and sample the bacteria in the lumen [55,56].…”

Intracellular replication ofSalmonella typhimuriumstrains in specific subsets of splenic macrophagesin vivo

“…Our work provides direct evidence showing that the majority of S. typhimurium bacteria reside within splenic macrophages, but it is also possible that a proportion of dendritic cells may be colonized. Indeed, a recent report demonstrates a role for dendritic cells in bacterial uptake by mucosal tissues as an alternative route to M cell invasion by S. typhimurium (Rescigno et al, 2001). It is possible that bacteria reach the spleen through dendritic cells, before colonizing resident marginal zone and red pulp macrophages.…”

Five different phenotypes of endothelial cell cultures from the bovine corpus luteum: Present outcome and role of potential dendritic cells in luteolysis

“…The cytokine could mediate the development of specific cell contacts to generate a microenvironment for limited molecule communication. The formation of tight junctions is reported for DCs when migrating through the gut epithelium (Rescigno et al, 2001) It is noteworthy that epithelioid CK + cell cultures from the ovarian surface epithelium display an IFN- dependent response, which is similar to cell-cell contact increase in treated CK + type 1 cells (Spanel-Borowski, 2011a). The similarity in function between the two CK + cell types might be dated back to a shared phylogenetic origin in the aorta-gonadomesonephric region as explained above.…”