Introducing the brain: controlling the gut (Introduction)

by David Turell , Thursday, May 29, 2025, 17:05 (4 days ago) @ David Turell

Through T cells:

https://www.nature.com/articles/d41586-025-01655-2

"Special-agent immune cells carry information about the gut and fat tissue deep into the brain. This surveillance system, uncovered in mice, is crucial to the brain’s control of behaviour such as pursuit of food, researchers report today in Nature1.

"Similar immune cells are known to populate the membranes covering the brain, but the newly identified cells have molecular traits that give them entry into the core of the organ. Their function is shaped by diet and the microbiome; without them, even hungry mice are slow to eat.

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"To gain a more definitive answer, Yoshida and her colleagues spent five years searching for T cells across the entire mouse brain. They found that T cells are concentrated in a hotspot in the subfornical organ, a structure in the centre of the brain that regulates a range of bodily processes, including eating and drinking. The scientists then sampled tissue from the human subfornical organ, where they also found T cells.

"In both mouse and human brains, the subfornical T cells were distinct from those found in the meninges. They produced more proteins that enabled them to reside in brain tissue and secreted more immune-signalling proteins known as cytokines under normal conditions.

"Curiously, the researchers found that the T cells from inside mouse brains were very similar to those in the animals’ fat deposits. To understand this similarity, they gave some mice a high-fat diet. These mice ended up with more T cells in their fat and brain tissues than did mice that ate standard food — evidence of a link between fat mass and brain T-cell populations. After mice on the same diet fasted for 48 hours, the number of T cells in their brains rose and the number in their fat fell, suggesting that food intake affects the number of T cells travelling to the brain.

"Next, the researchers used antibiotics to deplete populations of gut microorganisms in some mice. These animals’ levels of brain T cells decreased, which could mean that the microbiome influences immune-cell populations.

"Finally, the researchers assessed the potential role of the brain-resident T cells. Hungry mice that had been genetically engineered to lack the T cells took longer to find and consume food than did controls, suggesting that brain T cells play a part in feeding behaviour.

"More work is needed to uncover the mechanisms that enable brain T cells to influence eating and other functions, says Emanuela Pasciuto, a neuroimmunologist at the Vlaams Institute of Biotechnology in Antwerp, Belgium. This would require developing a whole new suite of tools that capture more than correlations, she adds. “That would be my wish experiment.'”

Comment: dhw will tell us how in tell us how intelligent the T cells are. This is a complex mechanism to control satiety, a very important function to halt overeating. It needs a designer not natural evolution,