Ultraviolet irradiation induces the production of multiple cytokines by human corneal cells

Purpose. Ultraviolet (UV) irradiation exposure represents a significant environmental and occupational hazard that can cause acute and chronic inflammatory changes in the exposed cornea. Acute exposure to solar UV irradiation or to UV irradiation from such artificial sources as tanning lamps can result in severe pain and inflammation in the cornea. Chronic exposure to solar UV irradiation is associated with several external eye diseases including pterygium and squamous metaplasia or carcinoma. In the skin, inflammatory responses to UV exposure appear to be mediated by the release of inflammatory cytokines. The role of corneal-derived cytokines in UV-mediated corneal inflammation has not been established. In this study, the effect of UV exposure on the production of proinflammatory cytokines by corneal cells was examined. Methods. Cultured human corneal stroma cells and whole human corneas received UV irradiation (10 to 100 mJ/cm ²), and the production of the proinflammatory cytokines interleukin (IL)-I, IL-6, IL-8, and tumor necrosis factor α (TNFα) was measured by Northern blot analysis, enzyme-linked immunosorbent assay, cytokine bioassays, and immunohistochemical analysis. Results. The results indicate that acute UV exposure leads to a significant increase in the production of IL-1, IL-6, IL- 8, and TNFα in human corneal stroma cells. Similarly, acute UV irradiation of whole human corneas ex vivo induces a significant increase in the production of IL-1 IL-6, IL-8, and TNFα. Conclusions. Acute UV irradiation exposure results in the induction of cornea-derived proinflammatory cytokines. The local release of these proinflammatory cytokines by cells in the irradiated cornea may be responsible for UV-mediated corneal inflammation.