Galacto-oligosaccharides alleviate experimental lactose intolerance associated with gut microbiota in mice

Abstract

Introduction: Galacto-oligosaccharides (GOS) are beneficial for alleviating lactose intolerance (LI). GOS have the ability to modify the composition of the intestinal microbiota. The development of intestinal diseases could be influenced by the composition of the gut microbiota. Nevertheless, it remains unclear whether gut microbiota exerts an effect when GOS alleviate LI, whether alterations in composition of the intestinal microbiota influence inflammatory response and lactose digestion.

Methods: We first investigated the effects of GOS on mice with established lactose intolerance. Next, we demonstrated that prophylactic supplementation with GOS also conferred similar benefits.

Results: The results showed that GOS enhanced anti-inflammatory, antioxidant, and gut barrier function. We observed that GOS mediated a change in the gut microbiome by increasing the abundance of Lactobacillus. GOS pre-supplementation reduced incident LI, enhanced anti-inflammatory, antioxidant, and gut barrier function, and markedly altered the gut microbiome by significantly enriching Bifidobacterium. Collectively, the alleviation of LI by GOS suggests an intimate involvement of probiotics.

Discussion: This study demonstrates that GOS ameliorated LI in a gut microbiota-dependent manner. Our findings provide novel evidence that GOS substitute for lactase and serve as a potential modulator of the gut microbiota for the prevention of LI.

Keywords: galacto-oligosaccharides; gut microbiota; lactase; lactose intolerance; mice.

FIGURE 1

GOS alleviated lactose-induced experimental LI. (A) Diagram illustrating the mouse model of LI employed in this study. (B) Oral normal saline and GOS treatments are indicated. Daily body weight changes throughout the entire duration of the study. (C–H) Concentrations of four representative pro-inflammatory cytokines, IL-1β, TNF-α, IL-6, IFN-γ, and anti-inflammatory cytokines, IL-4, IL-10 in the ileum. (I–M) GOS attenuated oxidative stress and jejunal damage. Concentrations of T-SOD, CAT, GSH-Px, MDA and ROS in the ileum from each group. (N) Concentrations of β-galactosidase in jejunum. (O–Q) Relative expression jejunal level of Occludin, ZO-1, Claudin mRNA in mice. Data were presented as means ± SEM (n = 8 per group). Statistical significance was determined using one-way ANOVA, followed by Tukey test. *P ≤ 0.05, **P ≤ 0.01.

FIGURE 2

GOS regulated the composition and function of intestinal microbiota. (A–C) α-diversity upon GOS represented by the Chao, Sobs and Shannon index. (D) PCoA plots upon GOS assessed by PERMANOVA. (E,F) The relative abundance of colonic contents bacterial phyla and genera presented in 99.5% of the community upon GOS. (G) Analysis of differences in the microbial taxa shown by Wilcoxon rank-sum test on genus level upon GOS. (H) Spearman correlation between intestinal microbiota and anti-inflammatory or anti-oxidative parameters in two groups. The red color denotes a positive correlation, while blue color denotes a negative correlation. The intensity of the color is proportional to the strength of Spearman correlation. Statistical significance was determined using one-way ANOVA, followed by Tukey test. *P ≤ 0.05, **P ≤ 0.01, ***P ≤ 0.001.

FIGURE 3

Prophylactic GOS attenuated signs of lactose-induced LI. (A) Diagram illustrating the experimental design in this study. (B) Daily body weight changes following lactose treatment. Statistical significance was determined using one-way ANOVA, followed by Tukey test. *P ≤ 0.05, **P ≤ 0.01 relative to CON group; ^##P ≤ 0.01 relative to GOS-L group. (C–H) Concentrations of four representative pro-inflammatory cytokines, IL-1β, TNF-α, IL-6, IFN-γ, and anti-inflammatory cytokines, IL-4, IL-10 in the ileum. (I–M) Prophylactic GOS attenuated oxidative stress and jejunal damage. Concentrations of T-SOD, CAT, GSH-Px, MDA and ROS in the ileum from each group. (N) Concentrations of β-galactosidase in jejunum. (O–Q) Relative expression jejunal level of Occludin, ZO-1, Claudin mRNA in mice. Data were presented as means ± SEM (n = 6 per group). Statistical significance was determined using one-way ANOVA, followed by Tukey test. *P ≤ 0.05, **P ≤ 0.01. ^a-cDissimilar letters represent significant difference among different treatments (P < 0.05).

FIGURE 4

Prophylactic GOS regulated the composition and function of intestinal microbiota. (A–C) α-diversity represented by the Chao, Sobs and Shannon index. (D) PCoA plots assessed by PERMANOVA among the four groups. (E,F) The relative abundance of colonic contents bacterial phyla and genera presented in 99.5% of the community in lactose-treated mice with or without receiving GOS. (G) Analysis of differences in the microbial taxa shown by using LEfSe (LDA coupled with effect size measurements). (H) Spearman correlation between intestinal microbiota and anti-inflammatory or anti-oxidative parameters among the four groups. The red color denotes a positive correlation, while blue color denotes a negative correlation. The intensity of the color is proportional to the strength of Spearman correlation. Statistical significance was determined using one-way ANOVA, followed by Tukey test. *P ≤ 0.05, **P ≤ 0.01, ***P ≤ 0.001.