Mechanical Stretching Modulates PGE2 and TGF-β1 Levels in Human Keratinocytes

Background Mechanical stresses affect biological processes, cellular homeostasis, and skin wound healing. Objective We investigated the effects of mechanical stretching on epidermal keratinocytes, focusing on its role in wound healing and keloid formation. Methods Epidermal keratinocytes were stretched using a biochemical stretch device with or without a cyclooxygenase-2 inhibitor. Cells and supernatants were collected after 1−24 h of stimulation. Stretched keratinocytes were co-cultured with normal dermal or keloid-derived fibroblasts. Prostaglandin E2 and 12-hydroxyeicosatetraenoic acid were measured via enzyme-linked immunosorbent assay. Prostaglandin E2 receptor EP3 and transforming growth factor-β1 (TGF-β1) were analyzed using qRT-PCR. TGF-β1 was also examined using western blotting. Prostaglandin E2 synthase and TGF-β1 were also stained and analyzed using immunofluorescence microscopy. Results Mechanical stretching of keratinocytes increased the levels of prostaglandin E2, which stimulates keratinocyte proliferation and exerts antifibrotic effects, as well as those of prostaglandin E synthase 2 and prostaglandin E2 receptor 3. In contrast, mechanical stretching did not affect the levels of transforming growth factor-β1 in affected keratinocytes. However, co-culture with keloid-derived fibroblasts markedly increased the levels of transforming growth factor-β1 in mechanically stretched keratinocytes. Conclusion Mechanical stretching induced PGE2 production and increased the TGF-β1 levels in keratinocytes in the presence of keloid-derived fibroblasts. Our results suggest that stretch stimulation in the presence of keloid-derived fibroblasts promotes keloid development.