"Unlike most cell types that can not tolerate bacterial contact, intestinal epithelial cells respond to Lactobacillus rhamnosus by increasing their motility," Neish says.
Using a fluorescent dye that is sensitive to reactive oxygen species (ROS), the researchers showed that intestinal epithelial cells produce ROS internally when in contact with Lactobacillus rhamnosus. The ROS induced by the bacteria stimulate the formation of focal adhesions, structures on intestinal epithelial cells that act as anchors for their movement.
"Focal adhesions are where cells attach to the matrix that surrounds them," Neish says. "The cells lay them down on one side and remove them on the other side, like the tracks of a bulldozer."
In studying the effect of Lactobacillus rhamnosus on intestines in mice, Neish's team focused on the small intestine, which normally has fewer bacteria than the colon. This allowed them to avoid using antibiotics to remove naturally existing bacteria beforehand, and to see ROS production in tissue from live animals.
Antioxidants that mop up ROS prevent the bacteria from promoting wound healing in the laboratory, the researchers showed. Neish says his team's finding suggests that large amounts of antioxidants by humans could interfere with the ability of bacteria to promote intestinal healing.
Previously, it was known that immune cells respond to bacteria by producing ROS, but Neish and his colleagues believe the ROS production they observed stimulates tissue maintenance and is a marker of cohabitation and adaptation, rather than defense.
Oxidative stress, or an imbalance of reactive oxygen species throughout the body, has been linke
|Contact: Kerry Ludlam|