With every bite of food we take, our intestinal immune system must make a big decision. Tasked with defending us from foreign pathogens, these exquisitely sensitive cells somehow distinguish friend from foe-destroying invaders while tolerating food and helpful bacteria. How the gut separates the good from the bad has long puzzled scientists.
Now, new research identifies specific gut cell types that communicate with T cells-prompting them to tolerate, attack, or simply ignore-and explains how these opposing responses are triggered. The findings, published in Science, give scientists a new understanding of how the intestinal immune system keeps the gut in balance, and may ultimately shed light on the root causes and mechanisms of food allergies and intestinal diseases.
“The big question is, how do we survive eating?” says lead author Maria C.C. Canesso, a postdoctoral fellow in the laboratories of Daniel Mucida and Gabriel D. Victora. “Why do our bodies normally tolerate food, and what goes wrong when we develop food allergies?”
Gut decisions
The intestinal immune system is complicated machinery. Tolerance to food begins with antigen presenting cells, or APCs, instructing T cells to stand down. This signal gives rise to pTregs, a special type of T cell that calms the immune response to food particles, and kicks off a cascade of activity involving additional immune cells that reinforce the message. But without knowing which specific APCs run the show, it’s difficult to tease out the ins and outs of the body’s eventual tolerance to food and intolerance to pathogens.
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