Both constitutive and inducible prostaglandin H synthase affect dermal wound healing in mice

In an attempt to define the roles of prostaglandin H synthase 1 (PGHS-1, cyclooxygenase-1, COX-1) and prostaglandin H synthase 2 (PGHS-2, cyclooxygenase-2, COX-2) in wound healing, we investigated the healing of incisional dermal wounds in wild-type, PGHS-1 null, and PGHS-2 null mice. We measured tensile strength of the wounds, levels of PGHS-1 and PGHS-2 mRNA in the wound site, and histologic markers for the inflammatory, proliferative, and remodeling phases of wound healing. Although no gross visible differences were noted among healed wounds of the different mouse types, measurement of tensile strength showed that both PGHS-1 and PGHS-2 null wounds were weaker (75% and 70%, respectively) than wild-type wounds at 12 days after incision. At Day 8 the endothelial staining was 70% greater in the wounds of PGHS-2 null mice compared with their wild-type counterparts. In contrast at Day 12, staining for macrophages and myofibroblasts was less in PGHS-1 null wounds compared with wild-type and PGHS-2 null tissue. Compensatory expression of the alternate PGHS mRNA could be demonstrated by RT-PCR in the wounds of PGHS null mice on Days 1 and 4. We conclude that both PGHS-1 and PGHS-2 genes play distinct roles in the process of dermal wound healing.