COLUMBUS, Ohio Stress not only sends the human immune system into overdrive it can also wreak havoc on the trillions of bacteria that work and thrive inside our digestive system.
New research suggests that this may be important because those bacteria play a significant role in triggering the innate immune system to stay slightly active, and thereby prepared to quickly spring into action in the face of an infection.
But exactly how stress makes these changes in these bacteria still isn't quite clear, researchers say.
"Since graduate school, I've been interested in how stress affects the bacteria naturally in our bodies,' explained Michael Bailey, an assistant professor of dentistry and member of the Institute for Behavioral Medicine Research at Ohio State University.
"Even though we've known that stress changes these bacteria, we didn't really understand what that meant or if there was any sort of biological function associated with effects on these bacteria."
The new study appears in the current issue of the journal Brain, Behavior and Immunity.
The human digestive tract is a universe filled with microbes. There are probably 100 trillion bacteria in the average human, 90 percent of which live mainly in the intestine. They easily outnumber human cells 10-to-one in each person.
Bailey and colleagues turned to mice to better understand the roles that bacteria play in immune balance. They ran a series of experiments using a common stressor for these animals. For two hours daily for six days, an aggressive mouse was placed in a cage of a group of more docile mice.
At the end of the string of experiments, blood samples were taken from both stressed animals and matched mice from a control group, along with samples of material from inside each animal's intestine. The blood samples were analyzed to detect the levels of two biomarkers used to gauge stress a cytokine called interleukin-6 (IL
|Contact: Michael Bailey|
Ohio State University