UTHCT scientist receives new funding for research that could lead to treatment for type 1 diabetes

Monday, February 20, 2006

When children are diagnosed with type 1 diabetes, it means they will need daily insulin injections for the rest of their lives. They are at risk for long-term complications such as heart disease and stroke, high blood pressure, blindness, nerve damage, kidney disease, and amputations. About one in every 400 or 500 children has type 1 diabetes, according to the American Diabetes Association.

A scientist at The University of Texas Health Science Center at Tyler wants to change that. Zhenhua Dai, Ph.D., MD, associate professor of immunology, is investigating how to alter the immune system so that insulin-producing cells can be successfully transplanted into children with type 1 diabetes.

Dr. Dai recently received a three-year, $300,000 research grant from the American Diabetes Association to fund this study, UTHSCT Vice President for Research Dr. Steven Idell said. Dr. Dai earlier had received two grants from the Juvenile Diabetes Research Foundation to support his research.

Type 1 diabetes is an autoimmune disease; the body’s immune system attacks the islet cells in the pancreas that produce insulin, Dr. Dai said. When these cells are destroyed, the body no longer produces insulin, a crucial hormone that enables the body to use sugar. Sugar provides fuel for cells’ necessary functions; insulin moves sugar, or glucose, from the blood into the cells.

One area of promise in treating this disease is islet transplantation, in which islet cells from a donor are transplanted into someone with type 1 diabetes, he said. Transplanted islet cells can produce insulin, thus eliminating the need for daily insulin injections, Dr. Dai said. However, the immune systems of individuals who receive these transplanted islet cells always reject them.

“These transplanted cells are seen as foreign tissue. We’re trying to find a way to prevent rejection by adjusting the body’s own immune system. That’s the challenge,” he said.

Islet cell recipients must take strong drugs to suppress their immune systems, allowing the cells to live and produce insulin, Dr. Dai said. But these drugs have serious side effects such as viral infections. Currently, individuals who receive transplanted islets or other organs must take immunosuppressive drugs for the rest of their lives.

Dr. Dai is exploring another way to control transplant rejection. If the rejection process could be stopped or managed, transplanted organs could be protected without powerful, dangerous drugs.

He and his team are focusing on a particular type of immune system cell, called a T cell. T cells lead the body’s attack against invading bacteria and play a key role in responding to transplanted tissue such as islet cells, Dr. Dai said. These T cells see the transplanted cells as foreign invaders and attack them, causing the body to reject them.

However, a small percentage of T cells – called regulatory T cells – are able to curb the rest of the T cells and stop the rejection of transplanted tissue, he said.

Dr. Dai wants to learn how to increase the effects of the regulatory T cells to prevent transplant rejection. He is studying how transplanted islet cells survive in the testes – part of the male reproduction system – where the immune system is naturally suppressed. Because the testes contain more regulatory T cells, the immune system is not as strong as in other areas of the body.

“Islets will produce insulin in the testes. They can stay there; they won’t be rejected. We want to study the mechanism of this process, to study why the immune system is weak here,” Dr. Dai said.

It remains unclear how the regulatory T cells manage to restrain the effects of the other T cells, he said. That’s the focus of his study: understanding what these regulatory T cells do and how they do it. If he’s successful, his research could lead to a permanent cure for type 1 diabetes.

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