Medical Update Memo
March 21, 2001

Summary
Researchers led by Dr. Michael Dosch, Hospital for Sick Children, Toronto, have published the results of two studies that provide more evidence of similarities between type I diabetes (juvenile) and multiple sclerosis. The researchers' work also suggests tentative evidence that high levels of consumption of cows' milk may have a role in the development of both diseases. The research is published in the April 1 and February 15, 2001 issues of The Journal of Immunology. The investigators plan to use this information to try to identify people who may be at risk of developing either MS or type I diabetes and to attempt to develop prevention strategies. An international diabetes prevention study is expected to begin later this year. A large international MS prevention study is in the planning stages, according to Dr. Dosch. The Multiple Sclerosis Society of Canada welcomes future study of these interesting observations.

Details
It has been known for some time that MS and type I diabetes (also known as juvenile diabetes) have a number of features in common. The two research studies published in the April 1 and February 15, 2001 issues of The Journal of Immunology provide more evidence of these similarities. The two diseases are quite different clinically. In multiple sclerosis, cells of the body's immune system attack the protective myelin covering of the central nervous system causing the many and varied symptoms of MS. In type I diabetes, immune system cells target the pancreas so that it can no longer produce insulin leading to the symptoms of diabetes. Approximately, 10 percent of people with diabetes have type I diabetes. Despite these clinical differences, earlier studies have reported related ethnic and geographic distribution as well as some similarity in genetic regions.

Immunological Work
In the work led by Dr. Michael Dosch, senior scientist at the Hospital for Sick Children, Toronto, the investigators found a high level of similarity in immunological reactions in both MS and type I diabetes. They analyzed T cell auto-reactivity in diabetes and MS by comparing immune system T cell responses in the test tube of 38 people with MS, 34 healthy controls and 54 newly diagnosed children with type I diabetes. They found that in people with MS and those with diabetes, there was a high degree of similarity in autoimmunity, and that the autoimmunity was not specific to the organ system affected by the disease. In the study, T cells from people with diabetes attacked central nervous system myelin proteins, and T cells from people with MS attacked proteins in the pancreas. In addition, the research team was able to develop an MS-like disease in a diabetes-prone mouse model.

Tentative Milk Link
The study published April 1 focused on the possible link of high cows' milk consumption to the risk of MS and type I diabetes developing in genetically susceptible people. The researchers found signs of abnormal immunity to cows' milk in the people with MS in the study. The possible link between cows' milk consumption and type I diabetes, multiple sclerosis and autoimmune diseases in general is an issue of some controversy. In the case of MS, various dietary triggers including consumption of dairy products have been suggested over the years, but the problem of designing and carrying out well-defined studies have left previous investigators without clear-cut conclusions.

Both Dr. Dosch and Dr. Paul O'Connor, director of the MS Clinic, St. Michael's Hospital in Toronto and member of the study group, cautioned that the results of the study were not substantiated enough to advise people to stop drinking milk, using dairy products or giving milk-based formula to babies. Genetic as well as environmental factors are suspected to be involved in both diseases. The investigators plan to use this information to try to identify people who may be at risk of developing either MS or type I diabetes and to attempt to develop prevention strategies. An international diabetes prevention study is expected to begin later this year. A large international MS prevention study is in the planning stages, according to Dr. Dosch.

Reaction of MS Society of Canada
According to Dr. William J. McIlroy, national medical advisor of the MS Society of Canada, the two studies provide interesting observations and new leads in studying both multiple sclerosis and type I diabetes. For MS prevention or intervention studies defining who may be at risk of developing MS (the "pre-MS" stage) will be more difficult since the familial incidence of MS is much lower than diabetes. The Multiple Sclerosis Society of Canada looks forward to the results of further investigations.

Disclaimer
The Multiple Sclerosis Society of Canada is an independent, voluntary health agency and does not approve, endorse or recommend any specific product or therapy but provides information to assist individuals in making their own decisions.