Neutrophils and Wound Repair: Positive Actions and Negative Reactions.

SIGNIFICANCE: Neutrophils are one of the most abundant cells of the immune system and they are extremely active during the repair of cutaneous wounds. In general, the antimicrobial activity of neutrophils is effective and allows these cells to carry out their primary function of preventing wounds from becoming infected. RECENT ADVANCES: It is now known that in addition to sterilizing the wound, the weapons used by neutrophils to kill potential pathogens can also cause significant tissue damage to the host. This additional damage can lead to delayed healing and excessive scar formation. CRITICAL ISSUES: Much of the host damage caused by neutrophils results from the activity of proteases secreted by these cells. The clinical significance of this problem is highlighted by numerous studies showing that high levels of neutrophil-derived proteases are associated with chronic, non-healing wounds. FUTURE DIRECTIONS: Studies are currently being performed to evaluate new ways of counteracting protease activity in chronic wounds. Additional studies will have to be carried out to determine whether neutralizing neutrophil proteases can improve the healing of chronic wounds without sacrificing the ability of neutrophils to eliminate pathogens and risking infection.