Thursday, February 6, 2003 – Page A12

OTTAWA -- For years, medical textbooks agreed: Type 1 diabetes, the kind that strikes in childhood, is not caused by diet.

That did not make life easier for Fraser Scott, an Ottawa medical researcher looking for for dietary reasons that cause the disease. How do you ask for money to investigate a connection that does not exist?

So a discovery by his research team is a little sweeter.

The team published findings in the Journal of Biological Chemistry showing that a wheat protein appears to cause some children's immune systems to attack the wrong target, damaging the body's cells and causing diabetes.

The idea came to Dr. Scott when he worked at Health Canada in the early 1980s. He was experimenting with mice bred to develop diabetes. When he put the mice on a restricted diet, he noticed they showed no signs of diabetes.

Maybe diet is important after all, he concluded. Wheat seemed a possible candidate: Children with Type 1 diabetes, once called juvenile diabetes, often have celiac disease, an inability to digest wheat. He examined wheat more closely.

Dr. Scott, Amanda MacFarlane and Karolina Burghardt at the Ottawa Health Research Institute, and colleagues at the University of Ottawa and in Finland, have isolated a protein in wheat that appears to cause the trouble.

They scanned one million candidate proteins from wheat, narrowing the field to three that caused reactions in the immune system, then to one that is linked to damage to the islets, parts of the pancreas that produce insulin, which helps cells break down sugar. Diabetes occurs when the pancreas loses the ability to produce insulin.

"To put it in the simplest terms, some individuals have an abnormal immune system," he said.

A proper immune system should attack germs in food, not the proteins, of which thousands are consumed every day.

When the immune system goes off course and attacks the wheat proteins, he suspects that it then attacks the pancreas' insulin-producing cells. The wheat mobilizes these disease-fighting cells into full-scale attacks but against the wrong target, he believes.

These destructive cells in the immune system "are just sitting there until something stimulates them," Dr. Scott said. "Then they expand, migrate to the pancreas, and cause a long period of inflammation that ultimately kills the beta cell," the cell that makes insulin. Other infections may play a role, possibly making this immune attack worse.

In his lab, a wheat protein, Glb1, caused blood from people and rats with diabetes to "light up" in immune reactions, appearing to clinch the link with diabetes.

If his findings hold up, this will be the first protein shown to cause at least some forms of diabetes.