The immune system relies on many different types of cells that work together after an injury. Among the earliest to reach damaged tissue are neutrophils, immune cells that were long viewed mainly as a cleanup crew responsible for removing debris.
New research from the Becker team shows that some neutrophils play a much more important role. A specific subgroup appears to help coordinate the immune response and shift it away from damaging inflammation toward conditions that support regeneration. The key signal involved is a molecule called Il-4.
Neutrophils Help Control Inflammation
To investigate how neutrophils influence healing, the researchers studied larval zebrafish, which are able to regenerate damaged spinal cords. They focused on what happens when these immune cells and the Il-4 signaling molecule are active at an injury site.
When the researchers inactivated this particular group of neutrophils, the immune response became unbalanced. Other immune cells produced excessive amounts of highly inflammatory proteins, creating an uncontrolled reaction. As a result, the zebrafish were unable to properly regrow nerve fibers and had difficulty recovering their movement.
