Researchers determine that multiple sclerosis
and diabetes are closely linked diseases.
A team of researchers led by Hospital for
Sick Children (HSC) senior scientist Michael
Dosch has determined that multiple sclerosis
and type I (juvenile) diabetes mellitus are
far more closely linked than previously thought,
including the role cow milk protein plays
as a risk factor in the development of both
diseases for people who are genetically susceptible.
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. |