Nowadays it’s quite rare to make real groundbreaking discoveries in the areas of anatomy and physiology. Starting with the dissections done a few hundred years ago, to state-of-the art imaging in the 20th and 21st centuries, scientists have basically mapped out the human body. Recently, however, a team of researchers at the University of Virginia School of Medicine led by Professor Jonathan Kipnis have made a discovery which could, as one expert put it, “change the textbooks.”
How the immune system interacts with the brain is a poorly understood mechanism. One of the reasons for this is because it has been traditionally held that the brain wasn’t connected to the lymphatic system, or at least, no one had yet to discover any link between them. Which is what makes the finding of this link between the brain and the immune system, consisting of previously unknown lymphatic vessels, such a big deal.
We all know what the brain does and why it is important, but what about the lymphatic system? In a nutshell, it’s part of the circulatory system and it consists of a series of vessels which carry a clear fluid called rightlymph through the body. In addition to the removal of fluids from the various tissues and some transporting duties, it is a very important component of the immune system. That’s because lymphatic system is the home of the T cells and B cells (collectively known as lymphocites), two of the most important components of the adaptive immune system – basically our body’s elite enforcers.
While looking for T-cell gateways into and out of the meninges (the membranes which cover the brain), the researchers found functional lymphatic vessels between one of these membranes and the brain. These structures were incredibly hard to find. They were only detected after Antoine Louveau, a postdoctoral fellow in Kipnis’ lab, developed a technique to mount a mouse’s meninges on a single slide so that they could be examined in their entirety. Scientists then noticed vessel-like patterns in the distribution of immune cells on these slides, and when they tested to see if there were any lymphatic, sure enough they found them.
A discovery like this one is bound to have a huge impact in the medical field. For example, we know that Alzheimer’s disease is caused by the build-up of big proteins chunks in the brain. A reason they might be accumulating is that they’re not being removed by these vessels. This breakthrough could also have implications in the treatment of other neurological conditions, from autism to multiple sclerosis. When you discover new structures in the brain you previously didn’t know existed, things are certain to get interesting.