What
Changes in the Immune System
Trigger
Type 1 Diabetes?
Like a carefully balanced house of
cards, one or more changes in the body’s immune system can trigger a cascade of
events that lead to type 1 (juvenile onset or insulin-dependent) diabetes. It’s
only after the cards have collapsed and the immune system has gone awry that
one can observe the destruction done: The body can no longer control blood
sugar (glucose) levels and daily insulin injections are required for the
individual to live.
What triggers the immune system to
attack its own insulin-producing beta cells in the pancreas, throwing off track
the body’s system for controlling blood sugar levels and obtaining energy from
food? Why does type 1 diabetes often develop in young children, while in others
it may take decades to develop?
These are some of the questions
being explored by Christophe O. Benoist, M.D., Ph.D., and Diane J. Mathis,
Ph.D., who head the Section on Immunology and Immunogenetics at Joslin in
Boston. Drs. Benoist and Mathis recently moved their world renowned research
laboratories from the Institute of Genetics and Molecular and Cell Biology in
Strasbourg, France, to Joslin. They also are professors of medicine at Harvard
Medical School.
Since 1984 the husband-wife
research team and their colleagues have been studying the intricate cellular
and genetic mechanisms that cause the immune system to turn against itself,
resulting in type 1 diabetes and other autoimmune diseases.
“The immune system has an element
of chance. Immune receptors are randomly generated so each person’s immune
system develops differently,” says Dr. Benoist.
“So in fact, we now know that even
identical twins do not, over time, have ‘identical’ immune systems. Studies
have found that it’s like shooting dice whether identical twins will develop
type 1 diabetes,” Dr. Mathis adds.
An estimated 800,000 Americans
have type 1 diabetes. Each year, 13,000 new cases of type 1 diabetes are
diagnosed in children and teenagers, making it one of the most common chronic
diseases in American children. Yet, it frequently occurs in people in their 30's
and beyond. About 85 percent of newly diagnosed cases of type 1 have no family
history of the disease, making it difficult on the surface to predict who will
develop it.
“Once type 1 diabetes has been
diagnosed, 95 percent of the insulin-producing islet cells already have been
destroyed. We want to understand the mechanisms so we can intervene early and
prevent the islet cells from dying. The ultimate goal is to diagnose children
before signs of the disease are even evident, and to then treat and alter the
autoimmune cascade,” Dr. Benoist says.
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