The approach grew out of a novel explanation, quickly gaining followers, for the mechanism of nerve damage caused by multiple sclerosis. Instead of concentrating on the alterations that result in autoimmune assaults on the nervous system, researchers led by Brian Popko of the University of Chicago have focused on a set of factors that prevent recovery from the inflammatory attacks.
A series of papers from Popko's lab has demonstrated that interferon-gamma -- a chemical signal used to activate the immune system -- plays a critical role in damaging the cells that produce myelin, the protective coating that lines healthy nerves. Interferon not only leaves these cells, called oligodendrocytes, incapable of repairing the damage but can also kill them directly.
"Interferon-gamma is not normally found in the nervous system," said Popko, the Jack Miller Professor of Neurological Diseases at the University of Chicago, "but it can gain entry after an inflammatory flare-up. We previously showed how it harmed oligodendrocytes. Here we confirm its direct harmful effects on those cells and demonstrate one way of protecting them."
The researchers produced a series of transgenic mice. In one set they introduced genes that produced interferon-gamma within the central nervous system. In another set they also introduced a gene (known as suppressor of cytokine signaling 1, or SOCS1) that blocked the response of myelin-producing cells to interferon-gamma.
Although transgenic mice with low levels of interferon-gamma showed no symptoms of nervous system damage, 18 out of 20 mice exposed to higher interferon levels developed difficulty walking, including mild to moderate tremors, within two weeks of birth. Only four o
Source:University of Chicago Medical Center