Agaricus subrufescens fermented rye affects the development of intestinal microbiota, local intestinal and innate immunity in suckling-to-nursery pigs
This study aimed to investigate the effects of a fermented feed additive -rye overgrown with mycelium (ROM) of Agaricus subrufescens - on pig intestinal microbiota, mucosal gene expression and local and systemic immunity during early life. Piglets received ROM or a tap water placebo (Ctrl) perorally every other day from day 2 after birth until 2 weeks post-weaning. Eight animals per treatment were euthanized and dissected on day 27 (one day prior to weaning) and days 44 and 70. Faeces, intestinal luminal contents, mucosal scrapings, blood and mesenteric lymph nodes (MLN) were sampled at different timepoints. ROM piglets had a lower inter-individual variation of faecal microbiota composition, a higher relative abundance of [Eubacterium]_coprostanoligenes_group, and a lower relative abundance of Peptostreptococcus compared to Ctrl piglets before weaning. Luminal microbiota composition was significantly different between ROM and Ctrl pigs in both jejunum and caecum on day 70 as based on pairwise unweighted UniFrac distances. Two proteobacterial genera (Undibacterium and Solobacterium) were only present in the jejunum of Ctrl pigs and two other proteobacterial taxa (Intestinibacter, Succinivibrionaceae_UCG_001) were present at higher relative abundance in the caecum of Ctrl pigs on day 70. Differences in gene expression (ROM versus Ctrl pigs) were identified in both ileum and caecum on day 44. In ileum, ROM supplemented pigs showed increased expression of tight junction protein TJP1/ZO1 but decreased expression of CLDN3 and CLDN5 and MUC2 compared to Ctrl pigs. Genes involved in TLR signalling (NFKBIA, TICAM2, NFKB1, IRAK4 and LY96) were more expressed but MYD88 and TOLLIP were less expressed in ROM pigs than Ctrl animals. NOS2 and HIF1A involved in redox signalling were either decreased or increased in ROM pigs, respectively. In caecum, expression of TNF, MUC2, IRAK1, IKBKB, PDGFRB, GLUT3, BCL2, CLDN5, CLDN3, TOLLIP and TNFAIP3 was higher in ROM pigs than in Ctrl animals, whereas BAX and MUC1 were less expressed. Moreover, ROM animals showed higher Natural Killer cell activation in blood and enhanced IL-10 production in ex vivo stimulated MLN cells before weaning. Collectively, these results suggest that ROM supplementation in early life modulates gut microbiota and (local) immune system development.