Epoxy fatty acids reduce corneal opacity and myofibroblast activation after alkali injury

Alkali-induced corneal injury causes epithelial damage, corneal opacity, stromal remodeling, and loss of transparency. Epoxy fatty acids (EpFAs), including epoxyeicosatrienoic acids (EETs) and epoxyeicosatetraenoic acids (EEQs), are rapidly hydrolyzed by soluble epoxide hydrolase (sEH). However, their roles in the corneal response to chemical injury remain incompletely defined. We evaluated the effects of EET, EEQ, and the sEH-resistant EET analogs in human corneal fibroblasts, human corneal epithelial cells, and mouse models of NaOH- and ammonia-induced corneal injury. In human corneal fibroblasts, EET and EEQ attenuated TGFβ1-induced α-SMA and collagen III expression, while EEQ also reduced collagen 1A1 expression. In human corneal epithelial cells, EET and EEQ increased the MTT signal after NaOH exposure and increased the percentage of Ki67-positive cells in uninjured cultures. Chemical exposure increased cellular sEH activity in a cell type- and injury-dependent manner. In the mouse NaOH injury model, topical EET or EEQ reduced corneal opacity and stromal α-SMA and fibronectin staining. The sEH-resistant analogs M2 and M4 also reduced TGFβ1-induced α-SMA expression and corneal opacity. Combining EET with TPPU or EC5026 reduced corneal opacity earlier than EET alone. In the ammonia injury model, EET treatment and genetic deletion of sEH were associated with lower corneal opacity and neovascularization scores. Together, these findings show that pharmacological or genetic modulation of the sEH-EpFA pathway modifies the corneal response to alkali injury and is associated with reduced corneal opacity and myofibroblast-associated marker expression. Further studies are required to define the molecular mechanisms linking this pathway to TGFβ signaling and immune responses.