Biochemical controls: T cells help gut immunity (Introduction)

by David Turell , Thursday, January 23, 2025, 19:25 (12 days ago) @ David Turell

new information on an old subject:

https://www.sciencedaily.com/releases/2025/01/250122145817.htm

"The cells that line your small intestine have to balance two seemingly contradictory jobs: absorbing nutrients from food, while keeping a wary eye out for pathogens trying to invade your body.

"'This is a surface where pathogens can sneak in," says La Jolla Institute for Immunology (LJI) Assistant Professor Miguel Reina-Campos, Ph.D. "That's a massive challenge for the immune system."

"So how do immune cells keep the gut safe? New research led by scientists at LJI, UC San Diego, and the Allen Institute for Immunology shows that pathogen-fighting immune cells called tissue-resident memory CD8 T cells (TRM cells) go through a surprising transformation -- and relocation -- as they fight infections in the small intestine.

"In fact, these cells literally rise up higher in the tissue to fight infections before pathogens can spread to deeper, more vulnerable areas.

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"Their work showed that the small intestine holds two types of TRM cells. These cells are split between the tiny, finger-like "villi" structures that line the small intestine or the "crypts" between the protruding villi.

"The researchers found that progenitor-like TRM cells live closer to the crypts between the villi. On the other hand, differentiated TRM occupy more exposed regions at the top of the villi. "Differentiated immune cells are more exposed at the top of the villi, and that's where they have a better ability to protect you from infections," says Reina-Campos.

Meanwhile, a reserve population of progenitor-like TRM cells continues to lie low in the "crypts. "These cells can replenish the pool of effector T cells, so the immune system keeps them as back-ups in the deeper parts of the tissue," adds Reina-Campos.

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"Looking at small intestines after a viral infection, the scientists found that the gut releases chemical signals to instruct immune cells where to go and what to do. "This study offers a new resource for finding signals that position immune residents to strengthen our gut immunity," says Reina-Campos.

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"The new study gives researchers a detailed look at how immune cells interact with each other and their cellular gameboard."

Comment: these specialized T cells are under tight chemical controls to place them exactly where needed. The control proteins are yet to be delineated. Another pure example of design.