Boosting the Immune System

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New study reveals that insulin is important for the immune system’s ability to fight infection.
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Insulin helps T cells to mount an effective immune response. T cells (depicted above, circulating in the blood) are a type of white blood cell that can recognize and kill invading bacteria and viruses.

The role of insulin in improving the ability of the immune system to fight infection has been described for the first time by Toronto General Hospital Research Institute (TGHRI) scientists.

The research findings were published in Cell Metabolism by first author Dr. Sue Tsai, postdoctoral fellow, and senior authors, Dr. Daniel Winer, TGHRI Scientist and Anatomical Pathologist at University Health Network; and Dr. Shawn Winer, Anatomical Pathologist at St. Michael's Hospital.

A fast and effective immune response protects us against infections, such as influenza. T cells are at the heart of this process: they divide rapidly and secrete chemical messenger proteins (cytokines) that direct the rest of the immune system to destroy the virus.

A lot of work has been done on insulin’s role in regulating blood sugar and how the body turns it into energy, yet little is known about how it affects the immune system.

The research team designed T cells that could no longer respond to insulin. They then observed what happened to the T cells after they exposed them to a flu virus.

They discovered that insulin gives the immune system the boost needed to fight the infection. Without it, the T cells were unable to effectively destroy the virus.

"T cells are at the heart of so many diseases," says Dr. Tsai, "Understanding them at the cellular level will give us the best opportunity to discover new pathways to target for new therapies." In the future, she says, we could harness this insulin signalling pathway to either boost the immune response to create vaccines, for example, or dampen it to heal inflammatory illnesses such as arthritis, ulcerative colitis and Crohn's disease.

Tsai S, Clemente-Casares X, Zhou AC, Lei H, Ahn JJ, Chan YT, Choi O, Luck H, Woo M, Dunn SE, Engleman EG, Watts TH, Winer S, Winer DA. Insulin Receptor-Mediated Stimulation Boosts T Cell Immunity during Inflammation and Infection. Cell Metab. 2018 Aug 22. pii: S1550-4131(18)30504-7. doi:10.1016/j.cmet.2018.08.003.

This work was supported by the Canadian Institutes of Health Research, Diabetes Canada, the J.P. Bickell Foundation Grant, the Banting and Best Diabetes Centre at the University of Toronto, and the Toronto General & Western Hospital Foundation. D Winer holds a Tier 2 Canada Research Chair in Immunometabolism. M Woo holds a Tier 2 Canada Research Chair in Signal Transduction in Diabetes Pathogenesis.

Dr. Sue Tsai, postdoc fellow, and Dr. Dan Winer, Toronto General Hospital Research Institute Scientist, get ready to test the effects of insulin on the immune system – a novel link that may have implications for vaccine development and inflammatory illnesses in the future. (Photo: UHN)