Researchers at the University of Virginia have discovered that blood vessels directly connect the brain to the body’s immune system. These blood vessels were never thought to have existed, despite the extensive research done on the lymphatic system. The findings were published online in Nature.
“This discovery is important because the brain is an immune privilege organ,” study author Antoine Louveau, Ph.D., a postdoctoral fellow at the University Of Virginia School Of Medicine, told Bioscience Technology. “Recently, we have seen that the areas that are surrounding the brain are full of immune cells, even in normal conditions, and that those immune cells are important in maintaining brain function. The discovery of those vessels mean that we are starting to understand how those areas work together and how they can be disrupted.”
Louveau discovered the vessels after analyzing the meninges of a mouse. According to reports, the vessels were very well hidden and follow another major blood vessel into the sinuses, which are very difficult to capture images of.
“Any neuroscience textbook that has ever been written will say that the central nervous system is devoid of a lymphatic system and that is one of the reasons the brain is immune privileged,” Louveau said. “When we started our project, our question was if there are so many immune cells surrounding the brain, how do they traffic there? By addressing this question we found vessels that weren’t supposed to exist. They were very well hidden and we think that is why it took so long to discover them.”
According to Louveau, the next step in the research will be learning whether the vessels exist in humans. He said it is very likely and that the vessels could play a major role in discovering the causes of neurological diseases.“Our research right now is going to go in two directions,” Louveau told Bioscience Technology. “The first question we are addressing is confirming that this structure exists in humans so our research can be relevant for diseases. The second point we are addressing is the role of the vessels in neurological pathology.”
While it is too early to tell, it is possible that these blood vessels could be related to a large number of neurological and developmental conditions from autism to attention deficit disorder (ADD) to multiple sclerosis. However, Louveau said the biggest focus has been on Alzheimer’s.
“I think the disease we have the most written about is Alzheimer’s, which is characterized by an accumulation of protein in the brain,” Louveau said. “We think that protein might start to accumulate in the meninges and block those vessels and that might start the disease progressing. We are still working on it, but we think these vessels should be involved.”
Because the discovery is so new, scientists do not yet know what role, if any, the vessels play in everyday brain function.
“We know that the immune cells around the brain seem to be important for normal brain function and we are going to address the question of how these vessels effect that normal brain function,” Louveau said. “They might have a role in normal brain physiology, but this is something we are going to work on because right now we don’t know.”