Therapeutic Targeting of Neutrophil Extracellular Traps Improves Primary and Secondary Intention Wound Healing in Mice

Abstract

Background: Neutrophilic granulocytes (NG) infiltrate tissue after trauma and mediate pro- and anti-inflammatory activities mainly through the formation of neutrophilic extracellular traps (NETs). NETs promote microvascular damage in the zone of stasis leading to impaired healing. We hypothesized that targeting NETs via DNase1 application and peptidyl arginine deminase type IV (PAD4) knock-out, reduces inflammation, promotes reepithelization and reduces scarring in an experimental model of primary and secondary injury. Methods: A cutaneous full-thickness wound was induced via either (1) surgical incision or (2) thermal injury of 93 C57BL6/J mice with 3 different genotypes: wildtype, PAD4-, and DNase1-Knockout (KO). Wildtype animals either received DNase1 or a vehicle via i.p. route. Wound assessment and euthanasia were conducted. Endpoints were macroscopic appearance (scar scale), time until full re-epithelization (H&E staining), scar structure (collagen I/III ratio, fiber organization and density), wound contractility (SMA), as well as activation of NG (NE, MPO) and NETs release (H3cit). Results: DNase1 treatment or PAD4-KO led to a significant improvement of macroscopic scar appearance and faster wound closure, while wound stability and contractibility was not negatively affected.