3D rendering of human dural lymphatics.eLife
A new study has revealed that the body’s immune system could play a key role in diseases such as multiple sclerosis and Alzheimer’s.
Researchers at the National Institute of Neurological Disorders and Stroke looked at both human and monkey brains and discovered lymphatic vessels (an essential component of the body’s immune system) in a membrane that surrounds the brain and nervous system.
The Lymphatic system is placed in the body much like the vast network of our veins and arteries, however, instead of blood, they carry lymph fluid which has within it both immune cells and waste products.
Using an MRI, the team injected a special dye into the bloodstream of several human volunteers and watched to see where it traveled.
They looked specifically at the dura mater or outermost membrane that protects both the brain and nervous system.
Some of the dye leaked out of blood vessels in the dura mater; they could also see that the leaked substance was collected by different vessels – this is exactly what occurs in the lymphatic system.
"That gave us some evidence that there are vessels here that are behaving different from blood vessels, but we weren't sure that they were lymphatic vessels,” said Dr. Daniel Reich, an author of the study and a senior investigator at the National Institute of Neurological Disorders and Stroke.
Notably, Reich and his team spent many years perfecting this dye technique to confirm the presence of these vessels.
Until a few years ago, scientists assumed that the brain’s immune system and process for removing waste were separate entities. This new evidence suggests otherwise.
Finding lymphatic vessels near the surface of the brain could lead to multiple breakthroughs, including a better understanding of the debilitating demyelinating disease, multiple sclerosis. The researchers have discovered confirmation that MS could be triggered by a glitch in the immune system.
"How the immune system interacts with the brain is fundamental to how multiple sclerosis develops and how we treat multiple sclerosis". Currently, the only treatments for MS include drugs that focus on suppressing the immune system.
Brain Spring Cleaning
This research adds to a landmark study published in 2013 which discovered that our brain uses sleep to flush out waste products, though it wasn’t known exactly how it did this.
The results found in that particular study suggested a prime reason why animals and humans sleep. During sleep, the flow of cerebrospinal fluid in the brain increases significantly, it then sweeps away harmful proteins that build up between brain cells during the day.
Dr. Maiken Nedergaard, a professor of neurosurgery at the University of Rochester and an author of the study in Science, compared the process to that of a dishwasher.
Nedergaard also found a correlation between this happening and Alzheimer’s. "Isn't it interesting that Alzheimer's and all other diseases associated with dementia, they are linked to sleep disorders," she says.
Now with this new finding regarding the lymphatic system, the understanding as to where all this waste is going is much clearer. Cumulatively, these discoveries are giving a huge boost to brain disease research.