Scientists Find Brain is Directly Connected to the Immune System Through Vessels

Posted on June 6, 2015

Diagram of the human lymphatic system old and new

Scientists at the University of Virginia School of Medicine have determined that the brain is directly connected to the immune system by vessels. These vessels were previously thought not to exist. The researchers call it a textbook-altering discovery. The above image shows the lymphatic system with the old diagram on the left and the updated version on the right.

Jonathan Kipnis, a professor in U.Va.'s Department of Neuroscience, says the finding entirely changes "the way we perceive the neuro-immune interaction." He says, "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. [It's] hard to imagine that these vessels would not be involved in a [neurological] disease with an immune component."

The vessels were detected after Antoine Louveau, a postdoctoral fellow in Kipnis' lab, developed a method to mount a mouse's meninges – the membranes covering the brain – on a single slide so that they could be examined as a whole. After noticing vessel-like patterns in the distribution of immune cells on his slides, he tested for lymphatic vessels and found them.

Louveau says, "It was fairly easy, actually. There was one trick: We fixed the meninges within the skullcap, so that the tissue is secured in its physiological condition, and then we dissected it. If we had done it the other way around, it wouldn't have worked."

Kipnis describes the vessels as being "very well hidden." They follow a major blood vessel down into the sinuses, which is an area that is difficult to image. Kipnis says, "It's so close to the blood vessel, you just miss it. If you don't know what you're after, you just miss it."

The discovery could have major implications on brain disease and disorders such as Alzheimer's, multiple sclerosis and autism. A research paper on the discovery was published here in the journal Nature.

Image: University of Virginia
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