Mucosal and Systemic Immune Responses Modulated by in Ovo-Delivered Bioactive Compounds in Distinct Chicken Genotypes

Abstract

BackgroundMucosal and systemic immune responses are different strategies to cope with environmental stimuli. In ovo delivery of prebiotic, probiotic, or synbiotic into the avian embryo allows for indigenous microbiota stimulation. Intestinal microbiota in animals is responsible for immune system maturation. The genetic component is critical in host-microbiota crosstalk and immune system development. The goal of this study was to compare mucosal and systemic immune responses in two distinct chicken genotypes stimulated in ovo. ResultsThe experiment was constructed in full-factorial design and was aimed to study the effects of two chicken genotypes (chicken broilers or native chickens), four in ovo-delivered compounds (GOS/galactooligosaccharides/prebiotic, Lactococcus lactis subsp. cremoris/probiotic, or GOS+L.lactis/synbiotic, vs. physiological saline) and three different stimuli (LPS or LTA vs. physiological saline) on a panel of cytokine genes (IL-1B, IL-2, IL-4, IL-6, IL-10, IL-12p40, and IL-17) expressed in caecal tonsils and spleen. We tested significance of the main effects and their interactions. Genotype had the most significant influence on all gene expression signatures in both tissues (P < 0.001 for all genes, except P < 0.05 for IL-10 in spleen). Immune challenge was the second most significant main effect, and influenced IL-1β, IL-6 IL-10 (P < 0.001), and IL-17 genes (P < 0.05) in caecal tonsils, and all genes in spleen (P < 0.001), except IL-4 (P > 0.05). In ovo stimulation influenced IL-2, IL-4, and IL-10 in caecal tonsils (P < 0.05), as well as IL-2 and IL-12p40 in spleen (P < 0.05). ConclusionsThe mucosal and systemic immune responses of chicken broilers and native chickens showed distinct patterns. Genotype influenced gene expression signatures of all immune-related genes, but chicken broilers developed stronger immune responses than native chickens. LPS triggered both mucosal (caecal tonsils) and systemic (spleen) immune responses in chicken broilers, but only systemic (spleen) in native chickens. In ovo stimulation with bioactive compounds (especially prebiotic) modulated innate immune responses to LPS. GOS delivered in ovo induced the most pronounced responses to LPS, which validated its further application as a potent immunomodulator for in ovo applications.