Human Milk Oligosaccharide Supplementation Affects Intestinal Barrier Function and Microbial Composition in the Gastrointestinal Tract of Young Sprague Dawley Rats

Human milk oligosaccharides (HMOs) are chief maternal milk constituents that feed the intestinal microbiota and drive maturation of the infant gut. Our objective was to determine whether supplementing individual HMOs to a weanling diet alters growth and gut health in rats. Healthy three-week-old Sprague Dawley rat pups were randomized to control, 2'-O-fucosyllactose (2'FL)- and 3'sialyllactose (3'SL)-fortified diets alone or in combination at physiological doses for eight weeks. Body composition, intestinal permeability, serum cytokines, fecal microbiota composition, and messenger RNA (mRNA) expression in the gastrointestinal tract were assessed. Males fed a control diet were 10% heavier and displayed elevated interleukin (IL-18) (p = 0.01) in serum compared to all HMO-fortified groups at week 11. No differences in body composition were detected between groups. In females, HMOs did not affect body weight but 2'FL + 3'SL significantly increased cecum weight. All female HMO-fortified groups displayed significant reductions in intestinal permeability compared to controls (p = 0.02). All HMO-fortified diets altered gut microbiota composition and mRNA expression in the gastrointestinal tract, albeit differently according to sex. Supplementation with a fraction of the HMOs found in breast milk has a complex sex-dependent risk/benefit profile. Further long-term investigation of gut microbial profiles and supplementation with other HMOs during early development is warranted.

The Effects of Human Milk Oligosaccharides on Gut Microbiota, Metabolite Profiles and Host Mucosal Response in Patients with Irritable Bowel Syndrome

Background: Human milk oligosaccharide supplementation safely modulates fecal bifidobacteria abundance and holds the potential to manage symptoms in irritable bowel syndrome (IBS). Here, we aimed to determine the role of a 4:1 mix of 2′-O-fucosyllactose and lacto-N-neotetraose (2′FL/LNnT) on the modulation of the gut microbiota composition and host mucosal response, as well as the link between the bifidobacteria abundance and metabolite modulation, in IBS patients. Methods: Biological samples were collected from IBS patients (n = 58) at baseline and week 4 post-supplementation with placebo, 5 g or 10 g doses of 2′FL/LNnT. The gut microbiota composition, metabolite profiles and expression of genes related to host mucosal response were determined. Results: Moderate changes in fecal, but not mucosal, microbial composition (β-diversity) was observed during the intervention with higher dissimilarity observed within individuals receiving 10g 2′FL/LNnT compared to placebo. Both fecal and mucosal Bifidobacterium spp. increased after 2′FL/LNnT intake, with increased proportions of Bifidobacterium adolescentis and Bifidobacterium longum. Moreover, the intervention modulated the fecal and plasma metabolite profiles, but not the urine metabolite profile or the host mucosal response. Changes in the metabolite profiles were associated to changes in bifidobacteria abundance. Conclusion: Supplementation with 2′FL/LNnT modulated the gut microbiota, fecal and plasma metabolite profiles, but not the host mucosal response in IBS. Furthermore, the bifidogenic effect was associated with metabolite modulation. Overall, these findings support the assertion that 2′FL/LNnT supplementation modulate the intestinal microenvironment of patients with IBS, potentially related to health.

The Effects of Human Milk Oligosaccharide Supplementation During Critical Periods of Development on the Mesolimbic Dopamine System

Human milk oligosaccharides (HMO)s are a key component in human milk and represent an important dietary modulator of infant gut microbiota composition and associated gut-brain axis development and homeostasis. The brain reward system, specifically the mesolimbic dopamine (DA) projections from the ventral tegmental area (VTA) to nucleus accumbens (NAc) is involved in the motivation and preference for food. The objective of the present study was to determine if HMO fortified diets given during the critical period of reward system development (p21) could affect the structure of the reward system. At weaning (p21), Sprague-Dawley rats were randomized to one of four fortified diet groups: Control, 3'sialyllactose (3'FL), 2'-fucosyllactose (2'FL), or a combination of 3'SL and 2'FL (3'SL + 2'FL). Messenger RNA (mRNA) expression was quantified for DA and appetite associated markers in the VTA and NAc and western blots measured the immediate early gene FosB and its isoform ΔFosB. Females fed the 3'SL + 2'FL fortified diet displayed a decrease in DAT expression in the VTA and an increase in leptin expression in the NAc. Females displayed an overall lower expression of NAc D2, VTA ghrelinR, and VTA leptin. In males, VTA DAT and FosB were negatively correlated with body weight and systemic leptin. Sex differences in the expression of DA markers underscore the need to investigate this phenomenon and understand the functional significance in preventing or treating obesity. This study highlights sex differences in response to HMO supplementation and the need for further investigations into the functional significance of nutritional interventions during DA system development.