Interleukin-6 in tear fluid after photorefractive keratectomy and its effects on keratocytes in culture

Purpose, To investigate the participation of interleukin-6 (IL-6) after photorefractive keratectomy (PRK) and its possible roles and sources in corneal wound healing. Methods, IL-6 levels were measured in the tear fluids of patients before and after PRK and in conditioned media of human corneal epithelial cells and keratocytes. Its effects on total collagen and collagen-type synthesis by keratocytes were studied with a H-3-proline incorporation assay and Northern blot analysis. Zymography was used to evaluate the metalloproteinase content in the conditioned medium of IL-6-stimulated keratocytes. Results, IL-6 is present in the tear fluid samples after photorefractive keratectomy, possibly synthesized by epithelial cells and keratocytes. Conclusions, IL-6 stimulates collagen synthesis in general and collagen type I in particular. Furthermore, it reduces the production of MMP-2, the latent form of the metalloproteinase, by cultured keratocytes. The results suggest that IL-6 might be regarded as a mediator involved in corneal healing after excimer laser.