2'-Fucosyllactose (2'-FL) changes infants gut microbiota composition and their metabolism in a host-free human colonic model

Abstract

Background: Breast milk is critical for neonates, providing the necessary energy, nutrients, and bioactive compounds for growth and development. Research indicated that human milk oligosaccharides (HMOs) have been shown to shape a beneficial gut microbiota, as well as their metabolism (e.g. short-chain fatty acids). 2'-Fucosyllactose (2'-FL) is one major HMO that composed of 30% of total HMOs.

Objectives: This study aimed to understand the impact of 2'-FL on the composition and metabolism of infant gut microbiota.

Methods: Our study utilized an in-vitro human colonic model (HCM) to investigate the host-free interactions between 2'-FL and infant gut microbiota. To simulate the infant gut microbiota, we inoculated the HCM system with eight representative bacterial species from infant gut microbiota. The effects of 2'-FL on the gut microbial composition and their metabolism were determined through real-time quantitative PCR and liquid-chromatography mass spectrometry (LC/MS). The obtained data were analyzed using Compound Discoverer 3.1 and MetaboAnalyst 4.0.

Results: Our study findings suggest that the intervention of 2'-FL in HCM resulted in a significant change in the abundance of representative bacterial species. PCR analysis showed a consistent increase in the abundance of Parabacteroides. distasonis in all three colon sections. Furthermore, analysis of free fatty acids revealed a significant increase in their levels in the ascending, transverse, and descending colons, except for caproic acid, which was significantly reduced to a non-detectable level. The identification of significant extracellular polar metabolites, such as glutathione and serotonin, enabled us to distinguish between the metabolomes before and after 2'-FL intervention. Moreover, correlation analysis revealed a significant association between the altered microbes and microbial metabolites.

Conclusions: In summary, our study demonstrated the impact of 2'-FL intervention on the defined composition of infant gut microbiota and their metabolic pathways in an in vitro setting. Our findings provide valuable insights for future follow-up investigations into the role of 2'-FL in regulating the growth and development of infant gut microbiota in vivo.

Keywords: 2′-FL; Gut microbiota; Human milk oligosaccharide; Infant; Metabolomics.

Figure 1:

Fold change of significant gut bacteria abundance change in (A) ascending, (B) transverse, and (C) descending colons comparing to pre-treatment phase. Significance was assessed by t-test (✱: p-value<0.05; ✱✱: p-value <0.01; ✱✱✱: p-value<0.005; ✱✱✱✱: p-value<0.001). Dotted line indicated 1-fold (no change). CP, Clostridium perfringens; SA, Staphylococcus aureus; BL, Bifidobacterium longum; PD, Parabacteroides distasonis; BA, Bifidobacterium adolescentis; SE, Staphylococcus epidermis; LA, Lactobacillus acidophilus; EC, Escherichia coli

Figure 2:

Box plots of free fatty acid regulation in (A) ascending, (B) transverse, and (C) descending colons from pre-treatment and treatment phase. Difference between pre-treatment phase and treatment phase was assessed by t-test (✱: p-value<0.05; ✱✱: p-value <0.01; ✱✱✱: p-value<0.005; ✱✱✱✱: p-value<0.001).

Figure 3:

Principal component analysis (PCA) plot of mass spectrometry-based metabolomics results for extracellular polar metabolites in (A) ascending colon, (B) transverse colon, and (C) descending colon in pre-treatment and treatment phase. P1, pre-treatment phase; P2, treatment phase.

Figure 4:

Volcano plots of mass spectrometry-based detection of extracellular polar metabolites in (A) ascending colon, (B) transverse colon, and (C) descending colon comparing treatment phase to pre-treatment phase (P2/P1). Significantly regulated metabolites were highlighted with blue (decreased) and red (increased) color. Significance was calculated by FDR-adjusted p-value (p < 0.05) with fold change (FC > 2).

Figure 5:

Correlation analysis of eight microbes and nine free fatty acids in (A) ascending colon, (B) transverse colon, (C) descending colon. Significance was calculated by Spearman correlation analysis (✱: ρ<−0.8 or ρ>0.8)

Figure 6:

Correlation analysis of eight microbes and significantly regulated extracellular polar metabolites in (A) ascending colon, (B) transverse colon, (C) descending colon. Significance was calculated by Spearman correlation analysis (✱: ρ<−0.8 or ρ>0.8)