Investigators from the University of Virginia (UVA) School of Medicine have discovered that the brain is directly linked to the lymphatic system through a network of well-disguised meningeal lymphatic vessels.

Overturning decades of teaching, the new discovery will allow clinicians to approach neuro-immune interactions mechanistically, Jonathan Kipnis, PhD, professor in the UVA Department of Neuroscience and director of UVA’s Center for Brain Immunology and Glia, said in a UVA press release. 

Map of the lymphatic system: traditional (left) and as redrawn by UVA’s discovery.

“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.”

Study author Antoine Louveau, PhD, a postdoctoral fellow, discovered the lymphatic vessels following a major blood vessel down into the sinuses, a finding that could have huge implications for diseases of the brain such as Alzheimer’s, multiple sclerosis and autism, to name a few. 

And considering the eye could be thought of as an extension of the brain, it could mean big changes to the future of eye care, too. “This may change our understanding of how certain inflammatory, infectious and degenerative neurologic disorders affect the optic nerves,” says Michael Trottini, OD, of Outlook Eyecare in New Jersey. “It may give further insight into the mechanisms of the optic neuropathies as well as optic neuritis and papilledema.”

“At this point there is no known lymphatic outflow from the eye, except for the lids and the conjunctiva,” says Carlo Pelino, OD, assistant professor at Pennsylvania College of Optometry at Salus University. 

He notes recent research is starting to reveal lymphatic endothelial markers in the eye, such as lymphatic vessel endothelial hyaluronan receptor one (LYVE1), transmembrane glycoproteins, VEGF R3 receptors and prox1 transcription factors.

“As eye care practitioners, we have to think, it’s not just the lymphatics in the lids and conjunctiva anymore, we have to look to see if there are lymphatics elsewhere in the eye,” Dr. Pelino says. “I think they are starting to come to that conclusion and this finding will really move things forward.” 

Louveau A, Smirnov I, Keyes T, et al. Structural and functional features of central nervous system lymphatic vessels. Nature. June 1, 2015. [Epub ahead of print].