November 23, 2017 (Medical News Today)
Understanding how immune cells are able to cross the blood-brain barrier and wreak havoc on the brain and spinal cord in individuals with MS is important to aid in the development of therapies to better treat this disease.
While looking for causes of MS, scientists found out that two types of white blood cell, lymphocytes Th1 and Th17, play a part in the destruction of the myelin sheath that coats and protects the axons of the central nervous system (CNS). It has not been clear until now how these immune cells were able to enter the blood-brain barrier into the CNS.
For this study, the blood-brain barrier was studied in healthy mice and mice with autoimmune encephalomyelitis (EAE), since mice with EAE are often used as models when studying MS. To find out how these immune cells are able to get across the blood-brain barrier in MS, investigators genetically used a fluorescent protein to label the tight junctions in the blood vessels. Results showed that these tight junctions were more damaged when Th17 cells were present. This damage also seemed to happen in very early stages of MS.
It was later discovered that these cells did not pass through into the CNS through the damaged tight junctions but did by passing through the endothelial cells by using “caveolae”. With this knowledge, researchers can now develop a drug to prevent or block this from happening.
Published in the journal Cell Reports.