Picture an older woman, perhaps your mother or grandmother. If she is a little tired, has thinning hair, or feels a bit cold, you might think it’s a natural part of aging. You could be wrong.
Those complaints are also some of the symptoms of a prevalent, yet easily treated disease called Hashimoto’s thyroiditis (HT), said Yi-chi Kong, PhD, professor of immunology and microbiology. "It afflicts 5-10 percent of the population, so it is quite common, especially in women and the elderly," she said. Like other autoimmune diseases where the immune system turns against different regions of the body, HT attacks the thyroid gland, knocking out the production of thyroid hormone.
Dr. Yi-chi Kong is trying to determine how HT is initiated and regulated.
"It’s so treatable, because you can just use a thyroid hormone for replacement. It’s not treating the disease itself, just the symptoms, but it works," she said.
Dr. Kong’s primary interest in the disease lies in its genetic component. With an $850,000, four-year National Institutes of Health grant renewal and assistance from longtime collaborator, Dr. Alvaro Giraldo, division chief of immunopathology at St. John Hospital and Medical Center, she is trying to learn how individual genes may confer resistance or susceptibility to the disease. Although HT appears to run in families, as do many other autoimmune diseases, it may skip some members of a family.
"Why do some people get it and some don’t?" Kong asked. The answer may lie in the combination of a person’s genes: If the genes that protect against the disease overshadow those that impart susceptibility, the disease may not appear, she explained. Her task now is to sort out the functions of specific genes that are suspected of conferring susceptibility or protection.
For her work, she is using transgenic mice, produced by longtime collaborator Dr. David Ebella at the Mayo Clinic. The mice carry one or two human genes. "By using individual genes, we can distinguish which one is involved in susceptibility," she said. "Once we have determined that, we can then put in double transgenes – two different genes – and see whether there is protection, which reduces susceptibility."
Already, they have shown that one of the transgenes, known as HLA-DR3, makes the mouse susceptible to Hashimoto’s thyroiditis. "With this information, we can go forward."
She added, "In addition, we want to identify the specific portion of the antigen involved." Here, she is distinguishing the similarities and differences between human and mouse thyroglobulin, the main protein in thyroid hormone.
"When we know these things, we can determine what initiates the disease, and what regulates it," she explained. "That is the major goal."