Immunity system complexity: protecting the brain (Introduction)

by David Turell , Thursday, March 17, 2022, 14:07 (770 days ago) @ David Turell

The blood brain boundary has skull channel openings for direct immune response:

https://www.sciencealert.com/there-are-secret-tunnels-connecting-your-skull-and-the-bra...

"...a team of medical researchers confirmed in mice and humans in 2018 – tiny channels that connect skull bone marrow to the lining of the brain.

"The research shows they may provide a direct route for immune cells to rush from the marrow into the brain in the event of damage.

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"The tiny tunnels were uncovered when a team of researchers set out to learn whether immune cells delivered to the brain following a stroke or meningitis originated from the skull, or the larger of the two bones in the shin – the tibia.

"The specific immune cells they followed were neutrophils, the "first responders" of the immune squad. When something goes awry, these are among the first cells the body sends to the site to help mitigate whatever is causing the inflammation.

***

"Using organ-bath microscopy – which uses a chamber full of solution to maintain the integrity of the isolated tissue while it is being examined – the team imaged the inner surface of a mouse's skull. There, they found microscopic vascular channels directly connecting the skull marrow with the dura, the protective membrane that encases the brain.

"Normally, red blood cells flow through these channels from the interior of the skull to the bone marrow; but, in the case of stroke, they were mobilized to transport neutrophils in the opposite direction, from the marrow to the brain.

"This was in mice, though. To find out if humans have something similar, the researchers obtained pieces of human skull from surgery and conducted detailed imaging.

"They noticed channels there as well; five times larger in diameter than the channels in the mouse skulls, in both the inner and outer layers of bone."

Comment: An amazing brain protection. this illustrates as aspect of immunity I've neglected, neutrophiles, the largest number of white cells circulating in blood. These are first responders as direct attack cells, antibodies not involved, since reacting and producing an antibodies takes time to appear. A beautifully designed system.