A Role for the Mouse 12/15-Lipoxygenase Pathway in Promoting Epithelial Wound Healing and Host Defense*□S

The surface of the eye actively suppresses inflammation while maintaining a remarkable capacity for epithelial wound repair. Our understanding of mechanisms that balance inflammatory/reparative responses to provide effective host defense while preserving tissue function is limited, in particular, in the cornea. Lipoxin A4 (LXA4) and docosahexaenoic acid-derived neuroprotectin D1 (NPD1) are lipid autacoids formed by 12/15-lipoxygenase (LOX) pathways that exhibit anti-inflammatory and neuroprotective properties. Here, we demonstrate that mouse corneas generate endogenous LXA4 and NPD1. 12/15-LOX (Alox15) and LXA4 receptor mRNA expression as well as LXA4 formation were abrogated by epithelial removal and restored during wound healing. Amplification of these pathways by topical treatment with LXA4 or NPD1 (1 g) increased the rate of re-epithelialization (65–90%, n 6–10, p < 0.03) and attenuated the sequelae of thermal injury. In contrast, the proinflammatory eicosanoids, LTB4 and 12R-hydroxyeicosatrienoic acid, had no impact on corneal re-epithelialization. Epithelial removal induced a temporally defined influx of neutrophils into the stroma as well as formation of the proinflammatory chemokine KC. Topical treatment with LXA4 and NPD1 significantly increased PMNs in the cornea while abrogating KC formation by 60%. More importantly, Alox15-deficient mice exhibited a defect in both corneal re-epithelialization and neutrophil recruitment that correlated with a 43% reduction in endogenous LXA4 formation. Collectively, these results identify a novel action for the mouse 12/15-LOX (Alox15) and its products, LXA4 and NPD1, in wound healing that is distinct from their well established anti-inflammatory properties.