Human gut is the largest body surface in contact with the external environment. It is a complex ecosystem combining gastrointestinal epithelium, immune cells and resident microbiota. Together, they cooperate to build up physical and chemical barriers to protect the host from potentially harmful microorganisms [1]. Probiotics may improve host health by modulating mucosal immune functions (e.g. mucin secretion, cytokine balance and antimicrobial peptides production). We previously developed an in vitro system that simulates the human gastro-intestinal (GI) tract, in which bacterial stress tolerance was examined. Lactobacillus plantarum WCFS1 [2], relative mutant strains (ΔctsrR, ΔftsH, Δhsp18.55) [3,4], and commercial probiotics exhibited appreciable survival to stresses of the human GI tract. Here we study the interaction of these bacterial strains with human colonic cells in terms of colonization ability and immune modulation. The adhesion propriety of the bacteria was analyzed on monolayers of differentiated and polarized Caco-2 cells. Intestinal cells were overlaid with bacteria in a ratio of 103:1 (bacteria: epithelial cells). The number of cell-associated bacteria was determined by CFU count on MRS plates. Among the three mutants analysed, ΔctsR showed significantly higher adherence with respect to wild type strain, similarly to the considerable adhesion of commercial probiotics. By qRT-PCR, the expression profile of a set of immune-related genes was analysed in Caco-2 cells, treated with either live or heat-inactivated bacteria. We observed up-regulation of HBD-2 and MUC-2 genes upon treatment with heat-killed cells of ΔftsH strain and differential induction of IL-6 and IL-8 genes by all the tested strains. References 1.Liévin-Le Moal V and Servin AL (2006) Clin Microbiol Rev 19: 315-337. 2.Kleerebezem M et al (2003) Proc Natl Acad Sci USA 100:1990–1995. 3.Fiocco D et al (2010) J Bacteriol 192:896-900. 4. Capozzi V et al (2011) Res Microbiol 162:419-
Interaction between probiotics and intestinal human epithelial cells: adhesion and induction of immune-related genes.
SPANO, GIUSEPPE;FIOCCO, DANIELA
2011-01-01
Abstract
Human gut is the largest body surface in contact with the external environment. It is a complex ecosystem combining gastrointestinal epithelium, immune cells and resident microbiota. Together, they cooperate to build up physical and chemical barriers to protect the host from potentially harmful microorganisms [1]. Probiotics may improve host health by modulating mucosal immune functions (e.g. mucin secretion, cytokine balance and antimicrobial peptides production). We previously developed an in vitro system that simulates the human gastro-intestinal (GI) tract, in which bacterial stress tolerance was examined. Lactobacillus plantarum WCFS1 [2], relative mutant strains (ΔctsrR, ΔftsH, Δhsp18.55) [3,4], and commercial probiotics exhibited appreciable survival to stresses of the human GI tract. Here we study the interaction of these bacterial strains with human colonic cells in terms of colonization ability and immune modulation. The adhesion propriety of the bacteria was analyzed on monolayers of differentiated and polarized Caco-2 cells. Intestinal cells were overlaid with bacteria in a ratio of 103:1 (bacteria: epithelial cells). The number of cell-associated bacteria was determined by CFU count on MRS plates. Among the three mutants analysed, ΔctsR showed significantly higher adherence with respect to wild type strain, similarly to the considerable adhesion of commercial probiotics. By qRT-PCR, the expression profile of a set of immune-related genes was analysed in Caco-2 cells, treated with either live or heat-inactivated bacteria. We observed up-regulation of HBD-2 and MUC-2 genes upon treatment with heat-killed cells of ΔftsH strain and differential induction of IL-6 and IL-8 genes by all the tested strains. References 1.Liévin-Le Moal V and Servin AL (2006) Clin Microbiol Rev 19: 315-337. 2.Kleerebezem M et al (2003) Proc Natl Acad Sci USA 100:1990–1995. 3.Fiocco D et al (2010) J Bacteriol 192:896-900. 4. Capozzi V et al (2011) Res Microbiol 162:419-I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
