Exposure of Bifidobacterium longum subsp. infantis to Milk Oligosaccharides Increases Adhesion to Epithelial Cells and Induces a Substantial Transcriptional Response

Abstract

In this study, we tested the hypothesis that milk oligosaccharides may contribute not only to selective growth of bifidobacteria, but also to their specific adhesive ability. Human milk oligosaccharides (3′sialyllactose and 6′sialyllactose) and a commercial prebiotic (Beneo Orafti P95; oligofructose) were assayed for their ability to promote adhesion of Bifidobacterium longum subsp. infantis ATCC 15697 to HT-29 and Caco-2 human intestinal cells. Treatment with the commercial prebiotic or 3′sialyllactose did not enhance adhesion. However, treatment with 6′sialyllactose resulted in increased adhesion (4.7 fold), while treatment with a mixture of 3′- and 6′-sialyllactose substantially increased adhesion (9.8 fold) to HT-29 intestinal cells. Microarray analyses were subsequently employed to investigate the transcriptional response of B. longum subsp. infantis to the different oligosaccharide treatments. This data correlated strongly with the observed changes in adhesion to HT-29 cells. The combination of 3′- and 6′-sialyllactose resulted in the greatest response at the genetic level (both in diversity and magnitude) followed by 6′sialyllactose, and 3′sialyllactose alone. The microarray data was further validated by means of real-time PCR. The current findings suggest that the increased adherence phenotype of Bifidobacterium longum subsp. infantis resulting from exposure to milk oligosaccharides is multi-faceted, involving transcription factors, chaperone proteins, adhesion-related proteins, and a glycoside hydrolase. This study gives additional insight into the role of milk oligosaccharides within the human intestine and the molecular mechanisms underpinning host-microbe interactions.

Breast Milk Oligosaccharides: Structure-Function Relationships in the Neonate

“…Chichlowski et al (27) showed that growth of B. infantis ATCC15697 on HMOs increases binding to intestinal epithelial cells in vitro, decreases release of inflammatory cytokines, and increases release of anti-inflammatory cytokines in response to an inflammatory stimulus. A similar increase in binding was determined using sialyllactose (69). These studies suggest that the specific growth phenotype of milk glycan–enriched bifidobacterial populations promotes persistence in situ and positively modulates the host epithelium.…”

Non-digestible carbohydrates in infant formula as substitution for human milk oligosaccharide functions: Effects on microbiota and gut maturation

“…The species that cannot utilize HMOs have a disadvantage and do not readily colonize. However, HMOs do not only serve as substrate for bacteria but they can also enhance Bifidobacteria persistence in the gastrointestinal tract by increasing their ability to bind to epithelial cells (Chichlowski et al 2012;Kavanaugh et al 2013). In the study of Wickramasinghe and collegues (Wickramasinghe et al 2015) it was found that both strain and carbon source affect binding affinity of Bifidobacteria to epithelial cells.…”

Bifidobacterium longum subspecies infantis: champion colonizer of the infant gut

“…First, as described above, B. infantis has a competitive advantage in the presence of human milk components; therefore, increased colonization resulting in decreased diversity of the gut microbiota and fewer luminal pathogens is one likely mechanism of protection. In addition to a selective growth advantage, in vitro studies reveal that B. infantis cells grown on HMO bind to cultured intestinal cells at a higher rate suggesting that the unique ability to grow on HMOs coincides with an increased ability to bind and colonize the intestinal mucus layer (65,66). …”