In addition to preventing infection, the immune system can also affect the brain and prevent animals from actively "dying"?

As we all know, the immune system plays an important role in protecting us against foreign bacteria, viruses and other pathogens, and is also the main force in the body to identify and remove dead cells, cancerous cells and other "garbage".
, however, the immune system seems to be not the only one with these "traditional functions".
factors in the immune system are also involved in cognitive function in the brain, affecting animal behavior, according to a recent study published in the journal Nature.
The scientists showed in mouse experiments that a group of immune cells distributed around the brain releases signaling molecules to nerve cells in the brain, keeping the animals anxious as necessary;
led by Professor Jonathan Kipnis of the University of Washington in St. Louis (WUSTL), the team first used techniques such as mass spectrometrometrometular analysis to analyze what immune cells were in the meninges of mice.
researchers liken the meninges to "the skin of the brain", which consists of three spongy protective membranes that surround the brain and spinal cord and separate nerve tissue from other parts of the body.
they found that a group of special immune cells in the meninges called gamma T cells produce lecierle mesotonin IL-17.
in general, this cytokine coordinates the immune response to infection by activating and guiding immune cells elsewhere in the body.
, however, the researchers found that when no infection occurred, the gamma T cells in the meninges continued to produce IL-17.
, how do these immune signals affect the brain? To explore the problem, the researchers used a variety of methods, including gene knocking or injecting antibodies into cerebrospinal fluids, to make some mice lack gamma T cells or reduce the expression of IL-17, and then compared them to other immunologic peers.
interestingly, the mice performed normally in memory, social behavior, foraging, mood, and other tests, with only a change in anxiety behavior.
for mice, the open spaces in the wild expose them to predators, so they have a certain fear of open space.
in tests simulating such scenarios, normal mice would choose to stand aside or hide in the shadows for safety.
, however, mice that did not have gamma T cells or low levels of IL-17 were fearless enough to stay in bright, open areas for long periods of time.
researchers note that this performance indicates a decrease in alertness and anxiety levels in mice.
, scientists found in the brain cortical layer of mice that the surface of nerve cells had a subject that responded to IL-17.
if those subjects were removed, nerve cells would not be able to detect IL-17, which would also reduce alertness in mice.
findings suggest that changes in animal behavior are not a by-product of the immune system affecting the brain, but rather an important component of immune-neural communication, the researchers said.
"by raising awareness, animals can avoid further infection or arrest in a debilitating state, thus contributing to survival."
de Lima, lead author of the study.
researchers also found the presence of gamma T cells in the human meninges through autopsies, saying the next step will be to explore whether too much or too little IL-17 is associated with anxiety and depression in humans.
Alves de Lima said: "In the future, we may also be able to treat mood disorders in humans by fighting IL-17.
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