AMES, Iowa -- It's commonly known that exercise among the elderly can keep them strong and active, but Iowa State University researchers are trying to find out if it can specifically enhance their immune responsiveness to infectious disease.
The National Institutes of Health has awarded ISU Associate Professor of Health and Human Performance Marian Kohut and her research team $2.5 million over the next five years to continue their research on the role of exercise in aging and resistance to influenza infection. Iowa State faculty joining Kohut on the project include Joan Cunnick, associate professor of animal science; Mike Wannemuehler, professor of veterinary microbiology and preventive medicine; Kyoung-Jin Yoon, professor of veterinary diagnostic and production animal medicine; and Dan Nettleton, associate professor of statistics. University of Iowa Assistant Professor of Pathology Kevin Legge is also part of the research team.
The team's objective is to identify mechanisms by which exercise may improve resistance to infection under conditions in which immune responsiveness may be compromised -- such as aging and stress.
"We propose that regular moderate exercise, as a mild repeated stressor, may result in adaptations that allow the organism to respond more efficiently to other stressors -- including infection," said Kohut.
Kohut reports that a better understanding of how exercise improves the ability to respond to stressors -- such as influenza infection in the body -- may provide insight into the way cells mediate the reduction in susceptibility to other diseases. "That information could potentially lead to the development of pharmacological strategies to minimize severity of influenza infection in older adults," she said.
The researchers have previously studied exercise and immune responsiveness in older human subjects, producing three papers since 2004 -- the first demonstrating that moderate exercise increases antibody response to influenza vaccine, and the most recent paper suggesting that exercise may have an anti-inflammatory effect. Published last February in the journal Brain, Behavior and Immunity, the paper found that cardiovascular exercise among the 87 human participants had a beneficial effect by reducing levels of multiple inflammatory factors that have been associated with chronic diseases (heart disease, diabetes, hypertension, etc).
"This positive effect appeared to be greater in the subjects who performed cardiovascular exercise as compared to those who participated in flexibility/strength/balance exercise," Kohut said.
The latest NIH grant will develop a new line of research using a mouse model -- allowing researchers to infect mice with influenza and measure immune response in specific tissues such as lung, lymph nodes and spleen.
"We have gone to the mouse model because there are many limitations in working with humans," said Kohut. "We can't ethically infect older adults with influenza and we can't readily collect cells from their lungs -- given that we are not at a medical school/hospital setting. Our new grant with the mouse model will allow us to more precisely define the mechanisms responsible for the effects of exercise on resistance to influenza infection and improvement of general immune response with aging.
"We think exercise may have an effect on some of the earliest defenses against influenza infection which occur within the respiratory tract, and using the mouse model will allow us to look within that site (lungs)," she said.
Kohut reports that the team plans to also continue its research on human subjects -- particularly exercise and its psychosocial effects -- and will be applying for grants this summer.
