A naturally occurring molecule produced by gut bacteria could help strengthen chickens’ immune response to a range of bacterial pathogens, according to new laboratory research.
The University of Bristol-led study found that sodium butyrate could “reprogramme” developing chicken immune cells, increasing their ability to kill bacteria including strains of E. coli and Salmonella.
Researchers said the findings could support the development of new gut-health strategies intended to improve disease resilience and reduce reliance on antibiotics.
However, the work was conducted in vitro, using primary chicken immune cells and cell lines, rather than in live birds. Further research will therefore be needed before the findings can be translated into practical interventions on poultry farms.
The study, published in The Journal of Immunology, involved researchers from the University of Bristol, the University of Surrey and The Pirbright Institute.
Developing immune cells reprogrammed
Sodium butyrate is a short-chain fatty acid naturally produced by bacteria in the gut.
Researchers exposed developing immune cells known as macrophages to the compound and found that it altered their subsequent response to bacterial infection.
The reprogrammed cells showed an increased ability to kill multiple strains of E. coli, Salmonella, Pseudomonas aeruginosa and Staphylococcus aureus.
Macrophages form part of the innate immune system, providing an early line of defence by detecting, engulfing and destroying invading pathogens.
The study also identified an important window during which the immune reprogramming occurred.
Sodium butyrate improved the antimicrobial activity of macrophages when it was introduced during the early, more adaptable stages of their development. Applying it to fully mature cells did not produce the same improvement.
The researchers said the finding provided an important indication of how any future intervention would need to be timed.
Alternative immune pathway
Unlike some agents used to train the innate immune system, sodium butyrate did not rely on generating high levels of inflammation.
Instead, it increased the production of reactive oxygen species, which immune cells can use to attack pathogens, and accelerated autophagy.
Autophagy is a cellular process through which cells capture, break down and remove damaged material or invading organisms.
Professor Shahriar Behboudi, Professor of Immunology at Bristol Veterinary School and senior author of the study, said the findings suggested trained immunity could take more forms than previously recognised.
“By demonstrating that a natural gut metabolite can program immune cells through an alternative, non-inflammatory axis, we open up exciting new possibilities for enhancing animal health naturally, without the collateral damage of excessive inflammation,” he said.
Potential role in reducing antibiotic reliance
Bacterial diseases including salmonellosis and infections caused by avian pathogenic E. coli remain significant health, welfare and economic challenges for poultry production.
The researchers said developing additional methods of improving birds’ resistance to infection could help the sector manage disease while reducing the need for antibiotic treatments.
Dr James Adams, Research Fellow in the School of Veterinary Medicine at the University of Surrey and first author of the paper, said bacterial diseases could cause substantial losses and disruption to poultry production.
“Antimicrobial resistance is complicating the management of disease in poultry,” he said.
“Therefore, it is crucial that we develop new ways of controlling bacterial infections in poultry.”
The study provides a research framework for exploring whether naturally occurring metabolic compounds could be used to influence immune development and improve flock resilience.
The research team hopes the findings will lead to further work on practical gut-health strategies that could improve bird welfare and contribute to efforts to tackle antimicrobial resistance.
The study was funded by the Biotechnology and Biological Sciences Research Council and the British Egg Marketing Board Research and Education Trust.
