HMO-primed bifidobacteria exhibit enhanced ability to adhere to intestinal epithelial cells

Abstract

The ability of gut commensals to adhere to the intestinal epithelium can play a key role in influencing the composition of the gut microbiota. Bifidobacteria are associated with a multitude of health benefits and are one of the most widely used probiotics for humans. Enhanced bifidobacterial adhesion may increase host-microbe, microbe-nutrient, and/or microbe-microbe interactions, thereby enabling consolidated health benefits to the host. The objective of this study was to determine the ability of human milk oligosaccharides (HMOs) to enhance bifidobacterial intestinal adhesion <i>in vitro</i>. This study assessed the colonisation-promoting effects of HMOs on four commercial infant-associated <i>Bifidobacterium</i> strains (two <i>B. longum</i> subsp. <i>infantis</i> strains, <i>B. breve</i> and <i>B. bifidum</i>). HT29-MTX cells were used as an <i>in vitro</i> intestinal model for bacterial adhesion. Short-term exposure of four commercial infant-associated <i>Bifidobacterium</i> strains to HMOs derived from breastmilk substantially increased the adherence (up to 47%) of these probiotic strains. Interestingly, when strains were incubated with HMOs as a four-strain combination, the number of viable bacteria adhering to intestinal cells increased by >90%. Proteomic analysis of this multi-strain bifidobacterial mixture revealed that the increased adherence resulting from exposure to HMOs was associated with notable increases in the abundance of sortase-dependent pili and glycosyl hydrolases matched to <i>Bifidobacterium bifidum</i>. This study suggests that HMOs may prime infant gut-associated <i>Bifidobacterium</i> for colonisation to intestinal epithelial cells by influencing the expression of various colonization factors.