Medical researchers, scouring the brain to peek into some of the deepest origins of multiple sclerosis (MS), claim they've uncovered some answers about the disease's onset.1
Uncovering Disease Origins
The scientists, at the University of California at Santa Barbara, peered into the mechanisms behind the unraveling of myelin when MS first strikes. Myelin is a fatty substance that surrounds and protects nerve endings in the brain. When MS occurs, it's believed an abnormal immune system attack targets myelin and strips it away, leaving the nerve endings exposed and vulnerable, and unable to conduct proper impulses between each other. The result is the symptoms that are often seen in MS.2
The researchers, led by Joe Zasadzinski, PhD, a professor of Chemical Engineering at UCSB, say they believe they understand why myelin becomes unraveled when MS first occurs in the body. The myelin sheath, they say, is made up of a fatty bilayer (similar to those making up the cell membrane) wrapped many times around the nerve axon—the part of the nerve cell through which impulses travel away from that cell. One specific protein known as myelin basic protein acts to hold the myelin sheath tightly around the axon. The axons serve as the electrical wires that connect nerve cells with each other, and myelin serves as insulation to keep the electrical impulses flowing quickly and reliably.
A Synergistic Relationship
"If the myelin breaks down for whatever reason, the nerve electrical impulses leak out, slow down, and generally don't work very well," Zasadzinski explained.
As MS progresses, Zasadzinski and his team theorize, there are small changes in the fatty composition of myelin. There is less negatively charged lipid, or fat composition, in the membrane, and more neutral, or uncharged, lipids. Myelin basic protein is positively charged, and gets in between the myelin's bilayers to link up the negatively-charged lipids and glue the myelin sheath together.
The scientists explain that the tightest binding of bilayers in myelin occurs when there is just the right amount of negative charge from the lipids to match the amount of positive charge from myelin basic protein. If there is too much of either one, the balance tips, and the bilayers start to repel each other rather than bind, sort of like what occurs when two magnets are held close together. "Although we can't say why the lipid composition changes, now with this new knowledge, perhaps we can suggest methods of trying to treat the unraveling before it gets too far along," said Zasadzinski.
He and his fellow researchers also learned that myelin basic protein acts as a patch to fill in any holes in the myelin bilayers. "It is similar to the stuff you put in your tires to fix punctures," Zasadzinski explained. "The myelin basic protein floats around until it finds a hole, binds to the edge of the hole, and then pushes the lipids to fill in the hole, insuring good insulation from the myelin sheath."
The California scientists say they hope their discoveries "lead to better treatments for demyelinating diseases such as multiple sclerosis."
It's estimated that about 400,000 Americans have multiple sclerosis, and every week, about 200 additional people are diagnosed. Around the world, more than 2 million people have been diagnosed with the disease.3
1. Hu Y, Doudevski I, Wood D et al. Synergistic interactions of lipids and myelin basic protein. Proc Natl Acad Sci USA 2004 Sep 14;101(37):13466-71. Epub 2004 Sep 7.
2. National Multiple Sclerosis Society. What is Multiple Sclerosis?
3. National Multiple Sclerosis Society. Who Gets Multiple Sclerosis?
John Martin is a long-time health journalist and an editor for Priority Healthcare. His credits include coverage of health news for the website of Fox Television's The Health Network, and articles for the New York Post and other consumer and trade publications.
