Researchers Determine That MS And Diabetes Are Closely Linked Diseases

Multiple sclerosis (MS) and type I diabetes mellitus are autoimmune disorders, where the body's immune system attacks its own tissue. The diseases are entirely different clinically, but have nearly identical ethnic and geographic distribution, genetic similarities, and, as is now known, shared environmental risk factors.

In a collaboration between The Hospital For Sick Children, St. Michael's Hospital and the Pittsburgh Children's Hospital, Dr. Dosch's laboratory discovered a high degree of similarity in the autoimmunity of MS and diabetes patients, and that a widely used mouse model for diabetes could also develop an MS-like disease.

"Much to our surprise, we found that immunologically, type I diabetes and multiple sclerosis are almost the same - in a test tube you can barely tell the two diseases apart," said Dr. Dosch, the study's principal investigator, a senior scientist in the HSC Research Institute, and a professor of Paediatrics and Immunology at the University of Toronto (U of T). "We found that the autoimmunity was not specific to the organ system affected by the disease. Previously it was thought that in MS autoimmunity would develop in the central nervous system, and in diabetes it would only be found in the pancreas. We found that both tissues are targeted in each disease."

In diabetes and MS, there is a long, drawn-out period of silent disease years before the appearance of symptoms and diagnosis of the disease. In diabetes, it is this "pre-diabetes" phase that is targeted by interventions to stop the development of the full-blown disease. Similar efforts are planned for individuals at high risk for MS.

"We are planning a large international study with centres in Canada and the US to test the possibility of interventions during the pre-MS phase," added Dr. Dosch.

One of the major environmental risk factors for diabetes is exposure to cow milk protein. Based on the role of cow milk protein as a risk factor in the development of type I diabetes, an international global diabetes prevention trial called TRIGR - Trial to Reduce Insulin-dependent diabetes in the Genetically at Risk - is expected to begin later this year, with Dr. Dosch as the trial's basic science chair. In the first step to test just how far the similarities between MS and diabetes go, the study's researchers looked for signs of abnormal immunity to cow milk in MS patients. Such abnormalities were indeed found in most patients, suggesting that similar processes may contribute to both diseases. If confirmed in a larger and prospective family study, it may become possible to design dietary means to influence the course of MS as well as diabetes.

"The similarities found between MS and type I diabetes will open new avenues of research. Our next focus will be to study MS family members for signs of early MS," said Dr. Paul O'Connor, head of the MS clinic at St. Michael's Hospital, a co-author of the study and Associate Professor of Neurology at U of T.

###Other collaborators on this research were: Shawn Winer, Igor Astsaturov, Roy K. Cheung, Lakshman Gunaratnam, Denise D. Wood and Professor Mario Moscarello, all from the HSC Research Institute; Colin McKerlie, Sunnybrook and Women's Health Sciences Centre and the University of Toronto; and Professor Dorothy J. Becker, Children's Hospital of Pittsburgh and the University of Pittsburgh.

Funding for this research was provided by the Canadian Institutes of Health Research, the Juvenile Diabetes Foundation, the Canadian Diabetes Association, the US National Institutes of Health and the Renziehausen Fund.