Pregnant women are not able to fight off infections caused by a common, but potentially serious, disease causing bacteria like listeria and salmonella. This is due to immune system supressing cells (called T cells) protecting the baby from attacks by the mother's immune system.

The University of Minnesota Medical School researchers have identifed the underlying mechanism for this physiologic immune system suppression that may lead to new therapies to help ward off infections during pregnancy. They published their findings in the July issue of Cell Host & Microbe.

Using a mouse pregnancy model, Dr. Sing Sing Way, an Assistant Professor in the Departments of Pediatrics and Microbiology, and his colleagues from the Center for Infectious Disease and Microbiology Translational Research have developed a method to dissociate the beneficial and detrimental impacts of maternal regulatory T cells (Tregs).

Specifically, when the immune suppressive molecule IL-10 is removed from regulatory T cells (Tregs) , mice were able to more efficiently combat infection against prenatal pathogens. Importantly, removing the IL-10 molecule did not have any negative impact on the outcome of the pregnancy.

"This research has identified that the immune cells critically required for sustaining pregnancy also causes pregnant women to be more susceptible to infection," Way said. "Our findings also uncover a potential immune-based therapy that can broadly boost resistance against infections during pregnancy without compromising pregnancy outcome."

Pregnant women don't always know when they have an infection, and sometimes the common signs and symptoms are masked during pregnancy, Way said. Delayed treatment can not only harm the health of the mother, but also cause infection in the developing fetus.

Published in the July issue of Cell Host & Microbe