Info the source of life; bile uses info for gut immunity (Introduction)

by David Turell , Sunday, January 05, 2020, 20:37 (1563 days ago) @ David Turell
edited by David Turell, Sunday, January 05, 2020, 20:42

Bile can trigger T cells:

https://www.sciencedaily.com/releases/2020/01/200103141047.htm

"The findings of the two studies, both conducted in mice, show that bile acids promote the differentiation and activity of several types of T cells involved in regulating inflammation and linked to intestinal inflammatory conditions. They also reveal that gut microbes are critical for converting bile acids into immune-signaling molecules.

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"The first study reveals bile acids exert their immune-modulating effect by interacting with immune cells in the gut. Once bile acids leave the gallbladder and complete their fat-dissolving duties, they make their way down the digestive tract where they are modified into immune-regulatory molecules by gut bacteria. The modified bile acids then activate two class of immune cells: regulatory T cells (Tregs) and effector helper T cells, specifically Th17, each responsible for modulating immune response by either curbing or promoting inflammation.

"Under normal conditions, the levels of proinflammatory Th17 cells and anti-inflammatory Treg cells balance each other, maintaining a degree of protection against pathogens without causing too much tissue-damaging inflammation. These cells play a key role in the context of intestinal infection. Th17 cells ignite inflammation to quell the infection, while Tregs curb inflammation once the threat has subsided.

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"'Our findings identify an important regulatory mechanism in gut immunity, showing that microbes in our intestines can modify bile acids and turn them into regulators of inflammation," said Huh, assistant professor of immunology in the Blavatnik Institute at HMS.

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To test the hypothesis that gut bacteria convert food-derived bile acids produced in response to food into immune signaling molecules, the researchers silenced bile acid-converting genes in various gut microbes and then put both the modified and nonmodified microbes in mice specially bred to have germ-free guts. Animals whose guts were populated by microbes without bile acid-converting genes had notably lower levels of Treg cells. (my bold)

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"'Our results demonstrate an elegant three-way interaction between gut microbes, bile acids and the immune system," said Kasper, who is professor of immunology in the Blavatnik Institute at HMS and the William Ellery Channing Professor of Medicine at HMS and Brigham and Women's Hospital."

Comment: Note my bold. Genes containing information are necessary in this process to modify bile molecules.