title: Intestinal colonization with bifidobacteria affects the expression of galectins in extraintestinal organs.
abstract: This study aimed at determining the contribution of intestinal bifidobacteria to the immune system activation using widely distributed galectins as markers of immune cell homoeostasis. In human flora-associated mice, bacteria were enumerated in the gut, blood, spleen, liver and lungs, while the expression of galectin-1 (Gal-1) and galectin-3 (Gal-3) was estimated by PCR in the intestine and real-time quantitative PCR in the other organs. Gal-1 and -3 were rarely expressed in the intestine. In blood, only Gal-1 was expressed while both galectins were expressed in all other organs. A high prevalence of colonic bifidobacteria was associated with a lower expression of both pulmonary galectins, whose levels negatively correlated with bifidobacterial counts. Caecal bifidobacterial counts also negatively correlated with pulmonary Gal-3 mRNA levels. The spleen was the only organ showing an upregulation of Gal-1 expression related to its bacterial contamination. However, this upregulation was only observed when bifidobacteria were not detected in the colon. A putative mechanism explaining the reduced expression of galectins when bifidobacteria highly colonize the mouse intestine could be that, by reducing the bacterial translocation, bifidobacteria also lead to a decreased blood concentration of substances produced by intestinal bacteria.
authors.affiliation: Laboratoire de Bactériologie-Virologie (EA3610), Faculté des Sciences Pharmaceutiques et Biologiques, Lille, France.
authors.forename: Marie-Bénédicte
authors.initials: MB
authors.lastname: Romond
authors.forename: Catherine
authors.initials: C
authors.lastname: Mullié
authors.forename: Michel
authors.initials: M
authors.lastname: Colavizza
authors.forename: Françoise
authors.initials: F
authors.lastname: Revillion
authors.forename: Jean-Philippe
authors.initials: JP
authors.lastname: Peyrat
authors.forename: Daniel
authors.initials: D
authors.lastname: Izard
mesh_terms: D000818:Animals; D001644:Bifidobacterium / Q000254:growth & development* / Q000276:immunology*; D001774:Blood Chemical Analysis; D002432:Cecum / Q000382:microbiology; D015169:Colony Count, Microbial; D037161:Galectins / Q000096:biosynthesis*; D041981:Gastrointestinal Tract / Q000382:microbiology*; D015870:Gene Expression; D008099:Liver / Q000737:chemistry; D008168:Lung / Q000737:chemistry; D051379:Mice; D016133:Polymerase Chain Reaction; D013154:Spleen / Q000737:chemistry
chemical_list: D037161:Galectins