by Rahul Jayaram '21
Of all the organs in the body, the brain is undoubtedly one of the most enigmatic. Today, there is still so much that is unknown in the field of neuroscience, and one can never predict when new discoveries will be made. The mechanisms behind how our brain maintains cellular health were always believed to be in a separate realm from the rest of our body. Just days ago, scientists discovered a game-changing facet about how the brain functions that has the potential to change the future of neuroscience research.
"The brain is thought to be what is called immune-privileged," explains Dr. Daniel S. Reich of The National Institute of Neurological Disorders and Stroke. "It has a different immune system from the rest of the body" . Cerebrospinal Fluid (CSF) is the brain's natural cleaning product that washes away the byproducts of cell metabolism and other excess substances. Likewise, lymph fluid flows in vessels throughout our body. This lymphatic system plays an important role in our body’s immune system, which maintains our health. For the past decades, it was believed that the brain’s waste removal system and the the water removal system of the rest of body were independent of each other. However, a recent study has shown that there is a direct relationship between the brain and our body’s immune system.
Dr. Reich used Magnetic Resonance Imaging (MRI) technology to show that lymphatic vessels exist in the tough skin-like material that surrounds the brain known as the dura. Reich’s lab used gadobutrol dye to track the blood of different people as it entered their cerebral blood vessels. Gadobutrol molecules are small enough to exit blood vessels but too large to penetrate the through the dura and be in contact with the brain. The conventional hypothesis should be that the dye would only be found in the blood vessels. However, when the MRI scanner was oriented a certain way, the dye could be seen forming new lines that did not resemble those formed by blood vessel regions. This observation suggested that the dye had entered lymphatic vessels. Reich was able to confirm his findings when his lab repeated the procedure with a dye too large to leave the blood vessels and no lymphatic patterns were seen .
Evincing that the immune system plays a critical role in brain function opens the door to many research possibilities for neurodegenerative diseases that have no known cure. For example, studies have shown that those affected by multiple sclerosis have abnormalities in their immune systems . Reich’s study could help unlock the currently unknown mechanism that is responsible for the onset of multiple sclerosis, potentially leading to a cure. Similarly, by further studying the immune system’s interaction with the brain, the treatment of Alzheimer's Disease and Parkinson’s disease becomes increasingly viable. Both Alzheimer's and Parkinson’s result from the buildup of harmful material in the brain, suggesting these diseases to be a result of immunodeficiency . By investing more time and effort into completely understanding the bridge between the immune system and the brain, research can come closer to checking them off the list of uncertainty in the medical field.
The creation of penicillin was first preceded by the discovery of bacteria. The polio vaccine was first preceded by the discovery of genetic transformation. It wasn’t until after one significant discovery in an abstruse scientific field that the floodgates for innovation were opened. It is imperative that fundamental changes in what we understand about a topic must take place before dramatic advancements can be made. To imagine what revolutionary neurological breakthroughs are set to follow this revelation is exhilarating.
 Hamilton, Jonathan. Brain's Link To Immune System Might Help Explain Alzheimer's. National Public Radio. 2017 [cited 2017 Oct 22]. Available from: http://www.npr.org/sections/health-shots/2017/10/03/555353033/brains-link-to-immune-system-might-help-explain-alzheimers
 NIH researchers uncover drain pipes in our brains. National Institute of Health [online]. 2017 [cited 2017 Oct 22]. Avaialble from: https://www.nih.gov/news-events/news-releases/nih-researchers-uncover-drain-pipes-our-brains
 Furtado G; Lira S. Neuroinflammatory Disease Induced by Cells of the Innate Immune System. Dana Foundation. 2007 [cited 2017 Oct 22]. Available from: http://www.dana.org/Media/GrantsDetails.aspx?id=38762