Modulation of microbial communities and mucosal gene expression in chicken intestines after galactooligosaccharides delivery In Ovo

Abstract

Intestinal mucosa is the interface between the microbial content of the gut and the host’s milieu. The goal of this study was to modulate chicken intestinal microflora by in ovo stimulation with galactooligosaccharides (GOS) prebiotic and to demonstrate the molecular responses of the host. The animal trial was performed on meat-type chickens (Ross 308). GOS was delivered by in ovo injection performed into the air cell on day 12 of egg incubation. Analysis of microbial communities and mucosal gene expression was performed at slaughter (day 42 post-hatching). Chyme (for DNA isolation) and intestinal mucosa (for RNA isolation) from four distinct intestinal segments (duodenum, jejunum, ileum, and caecum) was sampled. The relative abundance of Bifidobacterium spp. and Lactobacillus spp. in DNA isolated from chyme samples was determined using qPCR. On the host side, the mRNA expression of 13 genes grouped into two panels was analysed with RT-qPCR. Panel (1) included genes related to intestinal innate immune responses ( IL-1β , IL-10 and IL-12p40 , AvBD1 and CATHL2 ). Panel (2) contained genes involved in intestinal barrier function ( MUC6 , CLDN1 and TJAP1 ) and nutrients sensing ( FFAR2 and FFAR4 , GLUT1 , GLUT2 and GLUT5 ). GOS increased the relative abundance of Bifidobacterium in caecum (from 1.3% to 3.9%). Distinct effects of GOS on gene expression were manifested in jejunum and caecum. Cytokine genes ( IL-1β , IL-10 and IL-12p40 ) were up-regulated in the jejunum and caecum of the GOS-treated group. Host defence peptides ( AvBD1 and CATHL2 ) were up-regulated in the caecum of the GOS-treated group. Free fatty acid receptors ( FFAR2 and FFAR4 ) were up-regulated in all three compartments of the intestine (except the duodenum). Glucose transporters were down-regulated in duodenum ( GLUT2 and GLUT5 ) but up-regulated in the hindgut ( GLUT1 and GLUT2 ). In conclusion, GOS delivered in ovo had a bifidogenic effect in adult chickens. It also modulated gene expression related to intestinal immune responses, gut barrier function, and nutrient sensing.

Galacto-Oligosaccharides Modulate the Juvenile Gut Microbiome and Innate Immunity To Improve Broiler Chicken Performance

“…This would suggest that the impact of juvenile prebiotic feed is lifelong. Recently, Slawinska et al (48) have reported the delivery of galacto-oligosaccharides in ovo, which resulted in an increase in the relative abundance of Bifidobacterium-specific 16S rRNA PCRamplifiable sequences from the cecal contents of mature birds at 42 da, implying that the composition of the mature microbiota can be programmed in early development.…”

Splenic Gene Expression Signatures in Slow-Growing Chickens Stimulated in Ovo with Galactooligosaccharides and Challenged with Heat

“…Controls (the C group) were mock-injected with sterile physiological saline (n = 300, volume 0.2 mL/egg). Injection was carried out according to the in ovo procedure [32]. After hatching, the GOS and C groups were divided into two subgroups: maintained in thermoneutral condition (TN) and under the HS condition.…”

“…GOS that were delivered in ovo balanced the level of IL-10 and IL-12p40 to the baseline (under acute HS) or even down-regulated cytokine expression (under chronic HS). Previously, we have determined that GOS that were delivered in ovo increased the expression of the genes that are involved in the barrier function of the gut of broiler chickens [32]. An improved barrier function allows for a decrease of intestinal permeability due to stress and the influx of antigens into the milieu of the body [62].…”

“…During in ovo stimulation, a prebiotic or synbiotic is injected into the air cell of the incubating egg (in this study, on day 12 of egg incubation) and stimulates the development of indigenous microbiota prior to hatching [31]. The prebiotic supplementation at the embryonic stage supports not only the microbiota development in the growing chickens [32][33][34] but also improves the immune system [35,36], gut morphology [37] and the intestinal barrier function [32].…”

“…Galactooligosaccharides are potent prebiotics that exert beneficial effects on intestinal microbiota in chickens. Particularly interesting is the possibility of using in ovo technology for the early stimulation of the microbial communities with GOS [32,39,40]. The molecular data on broiler chickens have indicated that HS triggers systemic immune and stress responses, which are balanced by GOS that are delivered in ovo [41].…”