Immunity: protein signal molecule guiding brain neurons (Introduction)

by David Turell , Monday, September 14, 2020, 20:25 (1532 days ago) @ Balance_Maintained

A new study in mice:

https://medicalxpress.com/news/2020-09-immune-affects-mind-body.html

"What we've found here is that an immune molecule—IL-17—is produced by immune cells residing in areas around the brain, and it could affect brain function through interactions with neurons to influence anxiety-like behaviors in mice. We are now looking into whether too much or too little of IL-17 could be linked to anxiety in people."

"IL-17 is a cytokine, a signaling molecule that orchestrates the immune response to infection by activating and directing immune cells. IL-17 also has been linked to autism in animal studies and depression in people.

"How an immune molecule like IL-17 might influence brain disorders, however, is something of a mystery since there isn't much of an immune system in the brain and the few immune cells that do reside there don't produce IL-17. But Kipnis, along with first author and postdoctoral researcher Kalil Alves de Lima, Ph.D., realized that the tissues that surround the brain are teeming with immune cells, among them, a small population known as gamma delta T cells that produce IL-17. They set out to determine whether gamma-delta T cells near the brain have an impact on behavior.

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"Using mice, they discovered that the meninges are rich in gamma-delta T cells and that such cells, under normal conditions, continually produce IL-17, filling the tissues surrounding the brain with IL-17.

"To determine whether gamma-delta T cells or IL-17 affect behavior, Alves de Lima put mice through established tests of memory, social behavior, foraging and anxiety. Mice that lacked gamma-delta T cells or IL-17 were indistinguishable from mice with normal immune systems on all measures but anxiety. In the wild, open fields leave mice exposed to predators such as owls and hawks, so they've evolved a fear of open spaces. The researchers conducted two separate tests that involved giving mice the option of entering exposed areas. While the mice with normal amounts of gamma-delta T cells and levels of IL-17 kept themselves mostly to the more protective edges and enclosed areas during the tests, mice without gamma-delta T cells or IL-17 ventured into the open areas, a lapse of vigilance that the researchers interpreted as decreased anxiety.

"Moreover, the scientists discovered that neurons in the brain have receptors on their surfaces that respond to IL-17. When the scientists removed those receptors so that the neurons could not detect the presence of IL-17, the mice showed less vigilance. The researchers say the findings suggest that behavioral changes are not a byproduct but an integral part of neuro-immune communication.

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"To determine whether gamma-delta T cells or IL-17 affect behavior, Alves de Lima put mice through established tests of memory, social behavior, foraging and anxiety. Mice that lacked gamma-delta T cells or IL-17 were indistinguishable from mice with normal immune systems on all measures but anxiety. In the wild, open fields leave mice exposed to predators such as owls and hawks, so they've evolved a fear of open spaces. The researchers conducted two separate tests that involved giving mice the option of entering exposed areas. While the mice with normal amounts of gamma-delta T cells and levels of IL-17 kept themselves mostly to the more protective edges and enclosed areas during the tests, mice without gamma-delta T cells or IL-17 ventured into the open areas, a lapse of vigilance that the researchers interpreted as decreased anxiety.

"Moreover, the scientists discovered that neurons in the brain have receptors on their surfaces that respond to IL-17. When the scientists removed those receptors so that the neurons could not detect the presence of IL-17, the mice showed less vigilance. The researchers say the findings suggest that behavioral changes are not a byproduct but an integral part of neuro-immune communication.

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"'The immune system and the brain have most likely co-evolved," Alves de Lima said. "Selecting special molecules to protect us immunologically and behaviorally at the same time is a smart way to protect against infection. This is a good example of how cytokines, which basically evolved to fight against pathogens, also are acting on the brain and modulating behavior."

"The researchers now are studying how gamma-delta T cells in the meninges detect bacterial signals from other parts of the body. They also are investigating how IL-17 signaling in neurons translates into behavioral changes."

Comment: My comment would be God evolved this system. A specific protein is not likely a result of chance.