Immunofeed project: Searching the control of gut inflammation

The objective of this project is the reduction of antibiotics dependence in poultry production inducing a robust homeostatic state in the intestine (promoting tolerance and avoiding inflammation) while the defensive capacity against pathogens is increased. For that purpose, the control of metabolic pathways that modulate the intestinal immune response (tolerance/inflammation/defense) is needed to induce tailored responses. Previous studies showed that a blend with different bacterial strains obtained from a cecal chicken isolate is able to reduce 99% of cecal Salmonella colonization in day-old chicks challenged with 10⁴ cfu of S. typhimurium. The study of these strains provides an extraordinary opportunity to understand their mechanisms of action and to detect altered immune pathways. The hypotheses of this project sustain that probiotic strains with a high concentration of CpG motifs in their genome have a greater immunomodulatory capacity due to their capacity to activate apical (but not basolateral) TLR21 inhibiting the NF-κB pathway and reducing intestinal inflammation. Moreover, the mode of action of probiotics includes a greater ability to synthesize SCFA, which could result in a better epithelial protection (synthesis of mucins from increased goblet cells and excretion of sIgA) and recruitment of Treg cells (increase of tolerance). Moreover, selected probiotics could be able to increase the expression of host defense peptides conferring a greater defense capacity against Salmonella infection and persistence. First results have demonstrated that this blend includes 16 strains (>1% of relative abundance obtained by NGS). The most abundant strains detected are Shigella flexneri (20.3%), Pyramidobacter sp. (16.5%), Oscillibacter sp. (13.6%), Sutterella sp. (9.1%), Bacteroides fragilis (5.8%), Enterococcus faecalis (5.4%), and Bacteroides uniformis (3.1%). The percentage of GC of these strains varies between 37.3% and 63.6%. These strains have been isolated and their antimicrobial activity and adequacy as probiotics are being characterized. The most promising strains will be assessed in in vivo trials to demonstrate the hypotheses of the project.

Key Words: probiotics, poultry, gut inflammation, nuclear factor-κB (NF-κB), toll-like receptor (TLR)21.

Presented at the 9th Symposium on Gut Health in Production of Food Animals, St. Louis, USA, 2021. For information on the next edition, click here.