(RxWiki News) Research on multiple sclerosis is revealing more about what we don't know, than what we do know about the disease. One popular hypothesis on how the disease starts has now been disproven.
The trigger for the wayward immune response that drives the disease has long been a mystery.
One theory was that the death of the cells that produce myelin - the protective sheath wrapped around nerve cells - causes the disease.
But a new study has shown that damaged myelin, which characterizes the disease, is the result rather than the cause of multiple sclerosis.
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The study was led by neuroimmunologists from the University of Zurich, collaborating with scientists from Berlin, Leipzig, Mainz and Munich. They investigated the popular theory that cells called oligodendrocytes cause the onset of MS.
Oligodendrocytes are a type of brain cell that function to create myelin. Myelin is like insulation around nerve cells, and it helps the impulses in our brains speed along to their destinations.
Myelin damage, or demyelination, is the hallmark of multiple sclerosis, an autoimmune disease. Without myelin, the messages that our brain sends out can be slowed down or lost.
Multiple sclerosis attacks myelin in the central nervous system – the brain and spinal cord.
The theory that oligodendrocytes trigger MS came from the observation that some patients exhibited myelin damage without having an attack. It assumes that the immune system isn't involved in myelin damage. The researchers wanted to take a closer look.
To do so, they used laboratory mice, which is a popular way to mimic changes in the human body without testing on humans. The study authors managed to create myelin damage in the mice without triggering an immune system defense.
In their paper, they wrote that even when conditions were favorable to provoke an autoimmune response, the central nervous system did not experience the kind of inflammation that comes with multiple sclerosis.
As a result of their experiment, the study authors say that this popular theory is now obsolete. They believe that the answer to the important question of what causes MS may lie with the brain, rather than the immune system.
The paper was published in Nature Neuroscience in February 2012.