Study finds minocycline fights disease in rats
FRIDAY, Dec. 21, 2001
By Robin Foster
Multiple sclerosis (MS), a crippling disease of the central nervous system, could one day be treated with a common antibiotic, a new study suggests.
Researchers at the University of Wisconsin, in collaboration with German scientists, found that minocycline helped rats fight off a disease that's the animal equivalent of chronic MS in humans. The drug could decrease the severity of MS symptoms or even prevent relapses, they say. The findings appear in today's issue of the Annals of Neurology.
"It would either block the disease or lessen the severity of the disease. It protects the central nervous system," says senior author Ian Duncan.
One expert finds the results encouraging and exciting, but adds a caveat.
"I think we always have to temper our enthusiasm with a certain amount of caution until it's been tested on humans," says Nicholas G. LaRocca, director of health-care delivery and policy research at the National Multiple Sclerosis Society. Some treatments that have worked in the rat model of MS have been successful in humans, but many have not, he says.
Duncan acknowledges that, but he says the rat model is the best available model for MS, and it's used to test most MS drugs before human trials. And he says a human clinical trial already has been scheduled next year at the University of Calgary.
"We need to do more work to nail this down" to determine more specifically exactly how minocycline works on the nervous system, Duncan says.
MS, which affects more than 300,000 Americans, is characterized by inflammation and the loss of the myelin sheaths that protect the body's nerve fibers. Symptoms include numbness and possible paralysis, as the brain's ability to send signals to the rest of the body is weakened by the progressive destruction of myelin. The disease has no known cause or cure, and the triggers for relapses remain unclear. As the disease moves into its final stages, the sheaths are damaged and nerve fibers are destroyed.
But Duncan says minocycline, a member of the tetracycline family, seems to protect both.
"In MS, not only could it stop inflammation and protect myelin, it could also protect neurons themselves. We are exploring further aspects of the mechanisms of its effects and its neuroprotective properties," Duncan says.
In the study, researchers looked at four groups of rats: one group received a high dose of the protein that causes autoimmune encephalomyelitis (EAE) and was then treated with minocycline; a second group received a lower dose of the same protein to more closely resemble chronic MS; that group was then treated with minocycline. There were also were control groups for both the high-dose group and low-dose group. Whether the rats were treated before or at the onset of the disease, the antibiotic lessened the severity of symptoms and blocked relapses. Later, the drug was found to have protected both the myelin sheaths and the nerve fibers in the rats' brains.
Duncan says his team considered trying minocycline to treat MS because Finnish studies had shown the antibiotic stopped the activation of microglial cells, which patrol the brain and respond to immune events, in stroke patients. Microglial cells are one of the main culprits in MS and other neurological diseases, Duncan says.
Treating neurological diseases through microglial deactivation "may have much broader consequences," Duncan says.
LaRocca says the best answer may eventually come from a combination treatment, much like the drug cocktails doctors now give to AIDS patients.
"This is the really encouraging thing,
that there's so much going on in this area of research," he says. "Perhaps
a combination of drugs will work with MS."
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Copyright © 2001 ScoutNews, LLC