Sept. 18 (UPI) -- Blocking messages in lymphatic vessels from the brain to the immune system shows promise as a potential way to treat multiple sclerosis, according to a study.
Researchers at the University of Virginia School of Medicine, in a study of mice, found not only do these vessels play an important role in the development of multiple sclerosis but most likely other neuroinflammatory diseases and dangerous brain infections as well. Their findings were published Monday in the journal Nature Neuroscience.
Currently there is no cure for multiple sclerosis, a disease of the central nervous system in which communication between the brain and other parts of the body is disrupted. Symptoms of MS appear between the ages of 20 and 40, and can progress to disablement, according to the National Institute of Neurological Disorders and Stroke.
Most researchers believe MS is an autoimmune disease in which the body launches a defensive attack against its own tissues.
"Our data suggests that there is a signal coming from the brain to the lymph nodes that tells immune cells to get back into the brain, causing the [multiple sclerosis] pathology," Dr. Antoine Louveau, a researcher in UVA's Department of Neuroscience and Center for Brain Immunology, said in a press release. "This is an important proof of principle that exploring the role of these vessels in different neurological disorders, including multiple sclerosis, is worth it."
In mice, researchers impeded the development of multiple sclerosis by targeting the lymphatic vessels surrounding the brain. By blocking the lymphatics or destroying them with a precision laser, there was a decrease in the number of destructive immune cells capable of causing paralysis.
"The idea was to prevent more widespread damage to the nervous system," said Dr. Jasmin Herz. "If communication of brain inflammation through lymphatic vessels is the root cause of multiple sclerosis, therapies targeting these vessels could be clinically important."
Because researchers found removing the vessels did not stop multiple sclerosis entirely, they believe there likely are other factors at play.
Also, they don't know what the message is instructing the immune system to do.
"I think the next step in this specific research is to identify what that signal is. Is it a cellular signal, is it a molecular signal?" Louveau said. "And then to try to target that signal specifically."
The scientists found the function and role of the lymphatic vessels that connect the brain to the immune system work just like other lymphatic vessels in the body.
"Meningeal lymphatic vessels are quite small compared to other lymphatics in the body, and we and others wondered if this might limit the amount and size of cargo they can pass through," Herz said. "During inflammation, they did not change in size or complexity much, but what was really exciting to discover [was that] they allowed whole immune cells to traffic through them, and we found the molecular cues for that."
Although blocking the vessels showed benefits in the multiple sclerosis model, the vessels' healthy function is vital to staving off Alzheimer's disease and preventing the cognitive decline.
So, stopping MS won't be as simple as blocking the flow inside the vessels. But researchers see the discovery as an important step in tackling neurological diseases
"These findings on the role of brain-draining lymphatic vessels in MS, together with our recent work on their role in Alzheimer's disease, demonstrate that the brain and the immune system are closely interacting," said Dr. Jonathan Kipnis, chairman of UVA's Department of Neuroscience and director of the BIG Center. "When these interactions go out of control, pathologies emerge."
Kipnis is to explore potential clinical applications of his discoveries in a partnership with the company PureTech Health, which is developing medicines for dysfunctions of the brain-immune-gut axis.