Immunity system complexity: glia cells everywhere (Introduction)

by David Turell , Friday, June 03, 2022, 19:25 (690 days ago) @ David Turell

A new fascinating discovery:

https://www.sciencenews.org/article/glia-nerve-cells-brain-body-spleen-heart-lungs

"In recent decades, though, accumulating evidence has shown that glia are not just minor players that keep the show running. They actually play starring roles in many of the brain’s most important acts, such as remembering, learning and thinking.

"And the latest research points to a surprising new setting for the story of glia: outside the brain. Mysterious populations of glia reside in the heart, spleen, lungs and various other organs. But no one knows how they’ll fit into the plot. Early hints suggest the story is going to be riveting.

"Already, tantalizing clues are rolling in about what these cells are doing. Glia appear to help regulate the heart’s beating, for instance. Glia in the spleen reside right between nerve cells and immune cells — a perfect spot to influence the connection between health and stress. Exactly what glia are up to in the lungs is unknown, but whatever it is seems important, early experiments suggest — mice with no lung glia die.

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"Understanding the roles of glia outside the brain could have big implications for human health, leading to better ways to treat heart disorders, immune system problems and even lung cancer, some scientists suspect.

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"Researchers have a good handle on the roles of some glia outside the brain. Enteric glia help the gut digest food, for instance, and a type of glia called Schwann cells, sisters to the brain’s oligodendrocytes, spread myelin on peripheral nerves to help speed signals along. In the skin, specialized Schwann cells kick off pain sensations, scientists reported in Science in 2019. Less is known about glia in other organs, such as the spleen glia that intrigue Lucas. Naming these glia can be tricky, since the cells sometimes share similarities with multiple types of other glia. For now, these outsider glia are often lumped into one of two catchall categories, nonmyelinating Schwann cells or satellite glia.

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"The sympathetic nervous system and the immune system converge in the spleen, and glia may be particularly important in this connection. Experiments with the mice revealed big, complex glia in the spleen right alongside message-sending nerve cell axons. And “just microns away, there are immune cells,” Buckwalter says. The spleen’s glia are perfectly positioned to communicate between the nervous system and the immune system, the researchers reported in 2021 in Glia.

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"Research so far is preliminary. It’s not yet clear whether these spleen glia are in fact sending messages between the nervous system and the immune system, and if so, what the results of those conversations are. It’s too soon to say with any certainty that glia in people’s spleens are involved in autoimmune disorders, Buckwalter says. But the idea has piqued her interest.

"Studying these mysterious cells in organs feels like a different sort of science, she says. It’s harder than just trying to find a missing piece of a puzzle. “It’s like we just got a puzzle, and the pieces aren’t labeled and the box has no picture on it.”

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"It’s too soon to say whether glia outside the brain are part of the same story as the brain’s glia. The variety of glia residing outside the brain might all end up being individual bits of disparate biology, never coalescing into a plot that’s relevant for the entire nervous system, says Ransom, of the City University of Hong Kong. “I think it’s exciting and interesting work, and I think it’s completely justified to study it entirely,” he says. For now, there’s no telling where glia’s story will take us."

Comment: this research is dipping a toe into a whole new area of the biolgoy of life. Our understanding of all cell types is far from complete. Not at all like the completeness of the fossil record since Darwin's time.