Gut reaction: eating causes spike in immunity

Gut reaction: eating causes spike in immunity

Illuminate newsletter index page, March 2020
March 2020

Professor Gabrielle Belz and Dr Cyril Seillet
(L-R) Professor Gabrielle Belz and Dr Cyril Seillet

New research has revealed that the gut’s protective mechanisms significantly increase with food intake, and at times of the day when eating is expected.

In a preclinical study, Institute researchers showed that eating causes a hormone called vasoactive intestinal peptide (VIP) to activate immune cells in the gut. These cells respond to incoming pathogens or ‘bad’ bacteria.

Led by Professor Gabrielle Belz and Dr Cyril Seillet, the study also found that immunity increased at times of the day when eating was anticipated, indicating that regular mealtimes could be more important for health than previously thought.

Understanding the complex interactions between eating, gut immunity and inflammation could help to develop prevention and treatment strategies for chronic inflammatory diseases such as irritable bowel syndrome and Crohn’s disease.

The VIP of gut immunity

Professor Belz said it was the first time that food-induced activation of VIP had been shown to play a critical role in alerting the gut’s army of immune cells.

“When food is consumed, nerves in the intestine produce VIP that then signals to ILC3 immune cells. In response, ILC3s secrete interleukin-22, which defends against pathogens and maintains tissue integrity. It was clear that without VIP the immune system’s ability to prevent unwanted inflammation was impaired," she said.

Protection and prevention

In addition to being influenced by food intake, fluctuations in gut immunity were also driven by circadian rhythms, said Dr Seillet.

“We found that gut immunity also rises and falls due to an inbuilt cellular machinery regulated by the circadian clock gene Bmal1, which activates immune cells at times of the day when eating is expected,” he said.

While more work needs to be done to better understand this anticipatory mechanism, the results could help to explain why disruptions to regular eating patterns could increase chronic inflammation in the gut.

Dr Seillet said a detailed knowledge about mechanisms for gut protection and tissue repair could be useful for protecting against early-stage gut inflammation, before full-blown disease occurred.

“Next steps include gaining a molecular understanding of what properties of food are responsible for kickstarting the process of protective immunity. For example, do certain diets drive a more protective response than others?”

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