Chlamydia Bacterium Linked to Multiple Sclerosis

EMBARGOED UNTIL MAY 28

Media contact: Beckie Smith American Neurological Association (612) 545-6284 theresagutoski@compuserve.com

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STUDY LINKS CHLAMYDIA BACTERIUM TO MULTIPLE SCLEROSIS

Could a common bacterium be involved in the development of multiple sclerosis? In this month's Annals of Neurology, researchers report finding evidence of the bacterium Chlamydia pneumoniae in all the multiple sclerosis patients in their study.

If this microorganism, a common cause of "walk in pneumonia," turns out to be involved in the neurological disorder, the possibility exists that it could be effectively treated with available antibiotics.

Multiple sclerosis (MS) is a disorder of the nerve fibers of the brain and spinal cord. In MS patients, scarring (sclerosis) replaces myelin, a substance that normally insulates the nerves and speeds electrical conduction through the fibers.

Depending on which nerve fibers are hindered, patients can experience problems ranging from weakness and clumsiness to numbness, visual disturbances, and even emotional and intellectual changes. Some patients experience MS as cycles of relapse and remission; others progress to severe debilitation and may die from the disease.

Though the cause of MS is not known, circumstantial evidence has suggested it is an autoimmune disorder wherein the immune system's defense mechanisms mistakenly destroy the myelin. Consequently, research has been focused on finding the process that corrupts the immune system, and physicians have attempted, with limited success, to treat the disease with drugs that suppress the immune system.

On the other hand, a number of studies have suggested that an environmental agent, perhaps an infectious organism such as a virus, may be involved in the disease. However, attempts to isolate such an organism have failed.

Charles W. Stratton, M.D., and William Mitchell, M.D., Ph.D., pathologists at Vanderbilt School of Medicine in Nashville, Tennessee, and two authors of the paper, felt that C pneumoniae as an infectious agent in the disease was an intriguing possibility, and one that had not been looked at previously.

In part their suspicions were kindled by a report of abnormalities in the brain scans of patients whose blood had high levels of antibody to C pneumoniae. The abnormalities were similar to those seen in MS patients.

They alerted Subramaniam Sriram, M.D., a neurologist at Vanderbilt and senior author of the paper to this possibility. Sriram noted that the chlamydia family of bacteria typically cause chronic diseases with cycles of remission and relapse in other organs, similar to the common course of MS.

"We were lucky in finding an acute C pneumoniae infection in a patient with rapidly progressive MS. His dramatic recovery with antibiotics made us look more carefully at other patients," said Sriram.

The researchers searched for evidence of the organism in spinal fluid from 37 patients with MS. In all of these subjects, they found either the bacterium itself or other, indirect evidence that it was, or had been, present in the nervous system.

They found C pneumoniae itself in 64% of the patients. By comparison, they found the bacterium in only 11% of their control group, 27 patients who were undergoing spinal taps for neurological disease other than MS.

In almost all MS subjects they found evidence that the immune system had induced an antibody response to C pneumoniae. By contrast, only a few control subjects displayed antibodies--at low levels--to the bacterium.

"Could decades of looking for an infectious agent by the research community have missed a bacteria-sized organism or misinterpreted its presence?" asked Donald H. Gilden, a neurologist at the University of Colorado, in an editorial in the same issue of the Annals of Neurology.

He points out that it has happened before, most notably with the bacterium Helicobacter pylori, which was observed, and dismissed, in the stomachs of ulcer patients for decades before it was found to cause ulcers.

Both Gilden and the authors of the study caution that the challenge now is to determine whether C pneumoniae is involved in triggering MS in certain susceptible people, or whether it simply takes advantage of lowered defenses to infect people who already have MS.

"If further research establishes MS as an infectious disease, this will guide the development of therapy. There is also a good possibility of developing a vaccine to eradicate the disease," said Sriram.

Other authors of the report were Song-Yi Yao, M.D., Anthony Tharp, B.A., Ling Mei Ding, M.S., and Jason D. Bannon, Ph.D., also of Vanderbilt School of Medicine.