The human body’s macrophages—a type of immune cell—not only fight off invading pathogens, but also help repair injured tissue after an infection. Yale researchers have now discovered what triggers macrophages to switch from attack mode to rebuilding mode.
In a study published on June 9 in Science, Carla V. Rothlin, Ph.D., associate professor of immunobiology and of pharmacology, Sourav Ghosh, Ph.D., associate professor of neurology and of pharmacology, and colleagues found that when they blocked the ability of macrophages to sense the presence of cells that had died, the macrophages no longer switched on genes required to repair tissue, even when the immune molecules IL-3 or IL-4, which help both to activate macrophages and to signal early stages of infection, were also present.
Their finding in mice that signaling molecules and dead cells were both needed to activate cell repair may help scientists learn how better to spur healing after infections, and to develop therapies for chronic inflammatory diseases such as colitis.