Nobody knows what causes multiple sclerosis, the nervous system disease that affects more than 400,000 Americans, but new research sheds light on why the body is attacking itself and how to reverse it.

Researchers at the Stanford University School of Medicine have discovered how one protein could turn the tide against the degeneration found in the brains of MS patients, and actually reverse some of the worst effects of the disease.

The protein - alphaB-crystallin - is not usually found in the brain, but in the lens of the eye. It only develops in the brain in response to nerve cells that have been injured by multiple sclerosis.

Dr. Lawrence Steinman, professor of neurology and neurological sciences at Stanford, said his team showed how the protein played a protective role in mice with multiple sclerosis. "The big breakthrough in this paper is answering the question 'what is alphaB-crystallin doing,'" Steinman said in a news release.

These findings, to be published in Wednesday's online edition of Nature, also show that this protein reverses paralysis from nerve-cell injuries in mice.

Multiple sclerosis is an autoimmune disease where the immune system goes on attack against the fatty tissue called myelin that surrounds cells in the central nervous system, causing them to misfire.

For unknown reasons, when this protective protein appears in the brain, the immune system interprets it as a dangerous, and starts attacking it. "Like a runaway truck careening down a mountain and then having the brakes fall off, the immune attack against alphaB-crystallin worsens the situation," Steinman said.

The researchers found that adding the protein puts the brakes back on, returning control to the immune system. If the same results can be produced in humans, this protein could be an effective therapy for MS patients.

"It is a real delight to see that the same material that is naturally produced, (and) that has these protective effects, could potentially be harnessed and used as a therapeutic itself," Steinman said.

Steinman speculated that this restorative protein worked in the same way as an allergy shot. With an allergy shot, a mechanism called tolerization allows someone with allergies to get an injection of a protein that is causing problems for the body, and the body becomes accustomed to the protein and ignores it.

Researchers showed how injections of the protein in mice decreased inflammation and reduced other pathological conditions associated with MS. Steinman thinks the protein could reverse the cellular damage in humans that causes a range of symptoms from vision loss, to fatigue and paralysis.

"I am going to strenuously work to bring this from our benches to the bedside," Steinman said, "either through collaborations with existing companies, or we will start a new one."