Breaking into the brain

Researchers have found that immune cells must cross two distinct barriers in order to enter the brain. Understanding these processes may allow clinicians to slow down the inflammatory reactions that underlie conditions such as multiple sclerosis.

The two barriers discussed by Lydia Sorokin (Nikolaus Fiebiger Center for Molecular Medicine, Erlangen, Germany) and colleagues in the May 28 issue of The Journal of Cell Biology are both called basement membranes. One is made by the smooth muscle cells that line blood vessels, the other by brain cells. Sorokin reports that the muscle membrane contains two proteins called laminin 8 and laminin 10, but that immune cells only move through areas lacking laminin 10. The researchers report that immune cells stick to laminin 10 very strongly, and suggest that this adhesion may prevent cell movement. In contrast, sticking to laminin 8 is just sufficient to give the cells something to push against, but not too much to hold them back.

The immune cells do not stick at all to the two laminins (1 and 2) in the brain membrane. Instead of crawling over these laminins, the cells may use special proteins called metalloproteinases to blast a hole in the brain membrane. The end result of this movement is inflammation in the brain, as occurs when immune cells start attacking the myelin-sheathed nerve cells in the brain in the disease multiple sclerosis.

Contact: Lydia Sorokin, Interdisciplinary Center for Clinical Research (IZKF), Nikolaus Fiebiger Center for Molecular Medicine, Erlangen, Germany; 49 9131 8539301; [email protected]