Glycan Utilisation and Function in the Microbiome of Weaning Infants

Abstract

Glycans are present exogenously in the diet, expressed and secreted endogenously by host cells, and produced by microbes. All of these processes result in them being available to the gut microbiome, firmly placing glycans at the interface of diet–microbe–host interactions. The most dramatic shift in dietary sources of glycans occurs during the transition from the milk-based neonatal diet to the diverse omnivorous adult diet, and this has profound effects on the composition of the gut microbiome, gene expression by microbes and host cells, mucin composition, and immune development from innate towards adaptive responses. Understanding the glycan-mediated interactions occurring during this transitional window may inform dietary recommendations to support gut and immune development during a vulnerable age. This review aims to summarise the current state of knowledge on dietary glycan mediated changes that may occur in the infant gut microbiome and immune system during weaning.

Gut Bacteroides species in health and disease

“…9 Conjugated glycoproteins and glycolipids are examples of gut glycans, and these may be either O-linked (attached to serine or threonine residues) like host mucins, or N-linked (attached to asparagine), attached to cell surfaces as the glycocalyx, or unconjugated oligoglycans, which are often found in plants and fungi. 10 In the human body mucus is present at the interface between many epithelial surfaces and their environments and is prevalent in the GIT. 11 Interactions between the gut bacteriome and mucus are considered to be pivotal for the assembly and stability of the microbiota that reside in the gut.…”

Dietary Fucose Affects Macrophage Polarization and Reproductive Performance in Mice

“…The major bacteria growth-promoting factors in the intestinal mucus-derived O-glycans are often reduced upon colitis [ 21 , 49 , 50 , 51 ]. It is proposed that dietary glycans, like fucoidan, can partially substitute for the lack of the natural O-glycoside chains and have an ameliorating effect on inflammation and microflora composition [ 7 , 52 , 53 , 54 , 55 ]. However, to date, the impact of the external supplementation with mucus-derived glycans and their terminal monosaccharide fucose on pregnancy development remains unclear.…”

Galacto-oligosaccharides as infant prebiotics: production, application, bioactive activities and future perspectives

“…longum, B. breve and B. bifidum were found at three years of age (Nagpal et al 2017). Clearly, weaning represents a profound dietary transition with a major impact on the gut microbiota in which bifidobacteria are no longer the dominant component of this intestinal microbial community (Mckeen et al 2019).…”

“…Among the reported benefits elicited by an infant gut microbiota rich in bifidobacteria are: (i) degradation of nondigestible carbohydrates (Mckeen et al 2019), (ii) consequent production of beneficial metabolites, in particular short-chain fatty acids (Roberfroid et al 2009), vitamins, and lactic acid (Lee et al 2018), (iii) antimicrobial activity directed against pathogens and prevention of diarrhea (Aloisio et al 2012), (iv) inhibition of Enterobacteriaceae (Simone et al 2014), (v) anti-inflammatory activity (Khokhlova et al 2012), (vi) immune development (Dinan and Cryan 2017), and, last but not least, (vii) brain development (Dinan and Cryan 2017).…”