At mealtime, every mouthful of food contains a possible risk of incoming pathogens to the digestive system. The gut takes protective measures to account for this risk, and results from a new study suggest that the gut also takes cues from a regular eating schedule to deploy certain mechanisms accordingly.
The new study describes how the gut follows an individual’s eating schedule to collaborate with the immune system to protect the body. Understanding these mechanisms is important especially because inflammatory gastrointestinal (GI) conditions are becoming increasingly common, like irritable bowel syndrome (IBS) and Crohn’s disease. Additionally, these results highlight the significance of keeping a regular eating schedule that hasn’t been highlighted much before.
For example, if you eat lunch every day at noon, the gut might initiate certain activities every day around that time, even on the occasional day where you skip a meal or eat a late lunch, because the gut is accustomed to food intake on a specific schedule. This indicates that circadian clock genes might also be important in keeping the gut on schedule for boosting immune protocols in anticipation of mealtimes.
Researchers found that food intake triggers a “hormonal ‘chain reaction’ in the gut,” beginning with the vasoactive intestinal peptide (VIP) hormone produced in the nervous system. The VIP hormone initiates preemptive immune activity in the case that an upcoming meal contains any pathogenic microorganisms that hitched a ride on a piece of food. In theory, this works to protect against pathogens and preserve gut health.
In the new study, researchers found that VIP production as a result of an anticipated mealtime was required for activation of ILC3 immune cells to launch certain protocols to protect the gut from any incoming pathogens. Researchers were able to utilize a new imaging technique that can make tissues translucent to directly observe the relationship between VIP and ILC3. ILC3 cells produce interleukin (IL)-22, which plays a role in the gut immune defense. Without VIP, IL-22 production is limited.
"While more work needs to be done to better understand this anticipatory mechanism, the results are very interesting and could help to explain why disruptions to circadian rhythms and regular eating patterns could increase chronic inflammation in the gut,” explained co-study leader Dr. Cyril Seillet.
The next part of understanding the full picture of how the gut immune system responds to a regular mealtime schedule and how that affects inflammatory gut conditions is studying specific properties of food and how they influence the immune response.