News & Research

By: Felicia Breedy

31-October-2008 – Li Wen, MD PhD at Yale University in New Haven, Connecticut, and her colleagues have recently published important new research on the development of type 1 diabetes. Their results showed that mice exposed to common gut bacteria were protected against developing type 1 diabetes. Their research was featured in the September 22, 2008 issue of Science Daily. Dr. Wen is the recipient of an ADA Research Award for her project entitled, “The role of Toll in autoimmune diabetes.”

Dr. Wen and her colleagues used non-obese diabetic (NOD) mice for their experiments. These mice spontaneously develop type 1 diabetes. However, the environment in which NOD mice are kept can influence onset of the disease. From previous studies, researchers knew that mice exposed to non-active strains of disease-causing bacteria were protected against the development of type 1 diabetes.

In Dr. Wen’s study, NOD mice were made deficient in innate immunity, that is the part of the immune system that normally protects us from infections. These mice were protected from developing type 1 diabetes under normal conditions. However, when these mice lived in a germ-free environment, lacking harmless gut-bacteria normally found in the intestine, they developed severe diabetes. Thus, interaction of the innate immune system and gut bacteria appear to be important in delaying or preventing the onset of autoimmune type 1 diabetes.

Their findings support the “hygiene hypothesis,” a theory that a lack of exposure to common bacteria, viruses, and other immune system invaders, could cause an increased risk of allergies, asthma, and other immune system disorders in humans. These results could ultimately lead to treatment therapies that target the immune system, taking into account the exposure to gut-bacteria and their potential protective role in the development of type 1 diabetes.

(Wen L, Ley RE, Volchkov PY, Stranges PB, Avanesyan L, Stonebraker AC, Hu C, Wong FS, Szot GL, Bluestone JA, Gordon JI, Chervonsky AV. Innate immunity and intestinal microbiota in the development of Type 1 diabetes. Nature. 2008 Sep 21. [Epub ahead of print])