LAUSR

Lipid-regulated production of eicosanoids by cPLA2α directs the behaviors of dermal fibroblasts during wound repair. Lipids set the pace for wound repair Wound repair proceeds through distinct phases. Hemostasis and inflammation are followed by proliferation and remodeling, during which fibroblasts infiltrate the wound, proliferate, and secrete collagen, which is remodeled as the epithelium regenerates. MacKnight et al. observed increased fibroblast infiltration, collagen deposition, and tensile strength in skin wounds of mice in which cytosolic phospholipase A2 (cPLA2α), the rate-limiting enzyme in eicosanoid biosynthesis, could not be activated by the sphingolipid ceramide 1-phosphate (C1P). Wound tissue and dermal fibroblasts from these mice showed reduced proinflammatory prostaglandin production and increased 5-HETE, which promoted fibroblast migration and collagen deposition. These findings suggest that C1P promotes the inflammatory phase of wound repair and inhibits the proliferation and remodeling stages and show that cPLA2α-dependent eicosanoid production fine-tunes the behaviors of dermal fibroblasts during wound repair. The sphingolipid ceramide 1-phosphate (C1P) directly binds to and activates group IVA cytosolic phospholipase A2 (cPLA2α) to stimulate the production of eicosanoids. Because eicosanoids are important in wound healing, we examined the repair of skin wounds in knockout (KO) mice lacking cPLA2α and in knock-in (KI) mice in which endogenous cPLA2α was replaced with a mutant form having an ablated C1P interaction site. Wound closure rate was not affected in the KO or KI mice, but wound maturation was enhanced in the KI mice compared to that in wild-type controls. Wounds in KI mice displayed increased infiltration of dermal fibroblasts into the wound environment, increased wound tensile strength, and a higher ratio of type I:type III collagen. In vitro, primary dermal fibroblasts (pDFs) from KI mice showed substantially increased collagen deposition and migration velocity compared to pDFs from wild-type and KO mice. KI mice also showed an altered eicosanoid profile of reduced proinflammatory prostaglandins (PGE2 and TXB2) and an increased abundance of certain hydroxyeicosatetraenoic acid (HETE) species. Specifically, an increase in 5-HETE enhanced dermal fibroblast migration and collagen deposition. This gain-of-function role for the mutant cPLA2α was also linked to the relocalization of cPLA2α and 5-HETE biosynthetic enzymes to the cytoplasm and cytoplasmic vesicles. These findings demonstrate the regulation of key wound-healing mechanisms in vivo by a defined protein-lipid interaction and provide insights into the roles that cPLA2α and eicosanoids play in orchestrating wound repair.