The brain’s lymphatic vessels may offer a new way to treat multiple sclerosis.
The brain’s lymphatic vessels offer a new way to treat multiple sclerosis, according to new findings.
Investigators from the University of Virginia School of Medicine used animal models of multiple sclerosis in order to demonstrate the value of blocking these brain vessels can contribute to the amelioration of symptoms in mice. The team also discovered the lymphatic vessels in the brain; previously, the common belief was that they did not exist.
“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,” investigator Jasmin Herz, PhD, said in a statement. “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.”
The investigators first used a tracker injected into the vessels to monitor the flow in the mice. From that, they learned that the vessels have direct access to the cerebrospinal fluid. Additional trackers revealed several “hot spots” between the lymphatic vessels and the brain. They noticed that some hot spots picked up the injected tracer much faster than others. After further investigation, they realized that certain places along the vessels were more complex, especially when exposed to the cerebrospinal fluid.
With the use of various blocking strategies such as precision lasers, the investigators then tried to impede or destroy the lymphatic vessels. They found that each of the strategies resulted in a number of destructive immune cells. Removing the vessels from the brains did not stop multiple sclerosis, and so the investigators think other factors are involved.
“The idea was to prevent more widespread damage to the nervous system,” said Herz. “If communication of brain inflammation through lymphatic vessels is the root cause of multiple sclerosis, therapies targeting these vessels could be clinically important.”
The mechanisms behind multiple sclerosis remain a mystery. Scientists know that messages are being sent and the immune system is receiving instructions, but they don’t how those instructions are being transmitted. Targeting that specific signal could be the next target for therapy, according to the investigators, whether it is cellular or molecular, or something else entirely.
The team also thinks that this new finding can fend off Alzheimer’s disease onset and other types of age-related cognitive decline. Although this approach might not work for every neurological disorder, they said, it can provide a new avenue for exploration.
“These findings on the role of brain-draining lymphatic vessels in multiple sclerosis, together with our recent work on their role in Alzheimer’s disease, demonstrate that the brain and the immune system are closely interacting. When these interactions go out of control, pathologies emerge,” study leader Jonathan Kipnis, PhD, added in the statement. “The idea that we could target major neurological disorders through therapeutic manipulation of peripheral structures, such as lymphatic vessels, is beyond exciting.”
The study authors noted there were no side effects found while going through their proceedings, but as these targeted techniques develop, so could side effects.
The paper, titled “CNS lymphatic drainage and neuroinflammation are regulated by meningeal lymphatic vasculature,” was published in the journal Nature Neuroscience.