Immunity system complexity: gut cells protect the brain (Introduction)

by David Turell , Wednesday, November 11, 2020, 19:10 (1259 days ago) @ David Turell

The best way for pathogens to get the brain is through the blood from teh gut, so it is gut immune cells that protect the brain:

https://www.sciencenews.org/article/brain-infection-gut-immune-system

"A new study in mice finds that immune cells are first trained in the gut to recognize and launch attacks on pathogens, and then migrate to the brain’s surface to protect it, researchers report online November 4 in Nature. These cells were also found in surgically removed parts of human brains.

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"The most common route for a pathogen to end up in the bloodstream is from the gut. “So, it makes perfect sense for these [immune cells] to be educated, trained and selected to recognize things that are present in the gut,” says Menna Clatworthy, an immunologist at the University of Cambridge.

"Clatworthy’s team found antibody-producing plasma cells in the leathery meninges, which lie between the brain and skull, in both mice and humans. These immune cells produced a class of antibodies called immunoglobulin A, or IgA.

"These cells and antibodies are mainly found in the inner lining of the gut and lungs, so the scientists wondered if the cells on the brain had any link to the gut. It turned out that there was: Germ-free mice, which had no microbes in their guts, didn’t have any plasma cells in their meninges either. However, when bacteria from the poop of other mice and humans were transplanted into the mice’s intestines, their gut microbiomes were restored, and the plasma cells then appeared in the meninges.

“'This was a powerful demonstration of how important the gut could be at determining what is found in the meninges,” Clatworthy says.

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“'To my knowledge, this is the first time anyone has shown the presence of plasma cells in the meninges. The study has rewritten the paradigm of what we know about these plasma cells and how they play a critical role in keeping our brain healthy,” says Matthew Hepworth, an immunologist at the University of Manchester in England who was not involved with the study. More research is needed to classify how many of the plasma cells in the meninges come from the gut, he says."

Comment: Based on the source of pathogens in the gut, this design of brain immunity makes perfect sense. The source of Eben Alexander's E. coli meningitis is explained by this concept.