Brain and Immune System Missing Link Found By Researchers

A team of neuroscientists has found a previously unknown link between the immune system and the brain which may supply ammunition in fighting neurological conditions such as autism spectrum disorders, Alzheimer’s and multiple sclerosis in the near future.

The remarkable discovery contradicts decades of textbook knowledge.

University of Virginia School of Medicine researchers determined that the brain is connected directly with the immune system by vessels whose existence was previously unknown. That such vessels could have evaded detection when the lymphatic system has been so thoroughly mapped throughout the body is surprising in its own right.

However, the real importance of the finding lies is the impact it could have on research and treatment in the neurological field.

“Instead of asking, ‘How do we study the immune response of the brain?’ ‘Why do multiple sclerosis patients have the immune attacks?’ now we can approach this mechanistically. Because the brain is like every other tissue connected to the peripheral immune system through meningeal lymphatic vessels,” said professor Jonathan Kipnis, PhD, director of UVA’s Center for Brain Immunology and Glia (BIG). “It changes entirely the way we perceive the neuro-immune interaction. We always perceived it before as something esoteric that can’t be studied. But now we can ask mechanistic questions.”

“We believe that for every neurological disease that has an immune component to it, these vessels may play a major role,” Kipnis said. “Hard to imagine that these vessels would not be involved in a [neurological] disease with an immune component.”

Rewriting the Textbooks

On his reaction to the discovery, Kevin Lee, PhD, chairman of the UVA Department of Neuroscience, said:

“The first time these guys showed me the basic result, I just said one sentence: ‘They’ll have to change the textbooks.’ There has never been a lymphatic system for the central nervous system, and it was very clear from that first singular observation – and they’ve done many studies since then to bolster the finding – that it will fundamentally change the way people look at the central nervous system’s relationship with the immune system.”

Even Kipnis was skeptical initially. “I really did not believe there are structures in the body that we are not aware of. I thought the body was mapped,” he said. “I thought that these discoveries ended somewhere around the middle of the last century. But apparently they have not.”

The stunning revelation of the neural lymphatic vessels raises an overwhelming number of questions that now beg answers. They concern the workings of the brain and the diseases that plague it. For example, Alzheimer’s disease.

“In Alzheimer’s, there are accumulations of big protein chunks in the brain,” Kipnis said. “We think they may be accumulating in the brain because they’re not being efficiently removed by these vessels.”

The vessels, he explained, look different with age, therefore the role they play in aging is another mystery to investigate.

And there’s a huge number of other neurological diseases, from autism to multiple sclerosis, that must be reconsidered in light of the presence of something science was certain did not exist.

Elaine Hruska (2008)
Your Key to Good Health: Unlocking the Power of Your Lymphatic System

Jonathan Kipnis et al
Structural and functional features of central nervous system lymphatic vessels
Nature (2015) doi:10.1038/nature14432

Illustration: Maps of the lymphatic system: old (left) and updated to reflect UVA’s discovery. Credit: University of Virginia Health System