Objectives: Human milk oligosaccharides (HMOs) are the third most abundant component of breast milk. Our laboratory has previously revealed gene clusters specifically linked to HMO metabolism in selected bifidobacteria isolated from fecal samples of infants. Our objective was to test the hypothesis that growth of selected bifidobacteria on HMO stimulates the intestinal epithelium.
Methods: Caco-2 and HT-29 cells were incubated with lactose (LAC)- or HMO-grown Bifidobacterium longum subsp infantis (B infantis) or B bifidum. Bacterial adhesion and translocation were measured by real-time quantitative polymerase chain reaction. Expression of pro- and anti-inflammatory cytokines and tight junction proteins was analyzed by real-time reverse transcriptase. Distribution of tight junction proteins was measured using immunofluorescent microscopy.
Results: We showed that HMO-grown B infantis had a significantly higher rate of adhesion to HT-29 cells compared with B bifidum. B infantis also induced expression of a cell membrane glycoprotein, P-selectin glycoprotein ligand-1. Both B infantis and B bifidum grown on HMO caused less occludin relocalization and higher expression of anti-inflammatory cytokine, interleukin-10 compared with LAC-grown bacteria in Caco-2 cells. B bifidum grown on HMO showed higher expression of junctional adhesion molecule and occludin in Caco-2 cells and HT-29 cells. There were no significant differences between LAC or HMO treatments in bacterial translocation.
Conclusions: The study provides evidence for the specific relation between HMO-grown bifidobacteria and intestinal epithelial cells. To our knowledge, this is the first study describing HMO-induced changes in the bifidobacteria–intestinal cells interaction.
Foods for Health Institute, University of California, Davis, CA.
Address correspondence and reprint requests to David A. Mills, PhD, University of California, One Shields Ave, Davis, CA 95616 (e-mail: firstname.lastname@example.org).
Received 15 July, 2011
Accepted 30 December, 2011
The study was supported by award no. F32AT006642 from the National Center for Complementary & Alternative Medicine, the University of California Discovery Grant Program, the California Dairy Research Foundation, USDA NRI-CSREES award 2008-35200-18776, NIEHS Superfund P42 ES02710, and by NIH awards R01HD059127, R01HD061923, and R21AT006180.
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The authors report no conflicts of interest.