CAAT - MS "not what scientists think"

A group of researchers are claiming that, contrary to a century of medical understanding, multiple sclerosis (MS) is not an autoimmune disease, New Scientist magazine reports.

In a review to be published next week in The Journal of the Royal College of Physicians of Edinburgh, three neurologists suggest that understanding of MS has relied on unsound animal testing, and that scientists have been studying the wrong disease for more than 100 years.

Experts believe MS is caused when immune cells attack and destroy proteins that insulate nerves and help them conduct signals. But the forthcoming review argues that the disease happens when support cells in the brain and spinal cord, called astrocytes, break down, perhaps as a result of genetic and environmental triggers.

Professor Peter Behan and Dr Abhijit Chaudhuri from the University of Glasgow, and Professor Bart Roep from the Leiden University Medical Centre, in the Netherlands, criticise today's understanding of the disease on several fronts.

They say that when the autoimmune theory emerged, researchers discovered that if they injected nerve or brain tissue into an animal, its immune system would attack the nervous system. Experts called this experimental allergic encephalomyelitis (EAE), and adopted EAE as the "animal model" of MS.

But the researchers believe EAE is completely different from MS. It either kills animals or leaves them with permanent disabilities - it does not come and go like MS. Animals with EAE also suffer severe nerve inflammation, whereas in MS, inflammation is usually mild, if present at all.

Despite these inconsistencies, most MS treatments have been tested on EAE. According to New Scientist, Prof Behan says this could explain why these approaches have failed to cure a single person.

Instead, the group backs the idea that MS happens when astrocytes malfunction - studies suggest that astrocytes go awry in MS patients, says Prof Behan.

The damage then starts to spread, perhaps triggered by an as-yet unidentified chemical messenger. Prof Behan speculates that when the factor is released, MS patients experience periods of deterioration. The group adds there is some chromosomal evidence to support their hypothesis.

But the new theory is not without its critics. Dr Charles Poser of Harvard Medical School says the review ignores the exact match between the damage in people with MS and that in marmoset monkeys with EAE.

Traditionalists also dispute the argument that no treatments have worked. "None are cures," admits Stephen Reingold, of the National Multiple Sclerosis Society in New York. "But the immunoregulatory agents do provide relative benefits.and there are dozens of publications and regulatory approvals worldwide that attest to this."

But some experts are more encouraging. Dr Israel Steiner, at the Hadassah University Hospital in Jerusalem, believes EAE has blocked "effective progress" for decades.

"I definitely believe it's high time to reconsider the entire field. It has not led us into understanding the disease or to a better therapy for patients," he says.

Mike O'Donovan, chief executive of the UK's Multiple Sclerosis Society, said new research should be encouraged, provided it was balanced and comprehensive. "In this regard it should be noted that a number of experienced international researchers have disputed aspects of this paper," he said.