PURPOSE: The authors previously showed that the expression of various junctional proteins in corneal epithelial cells or corneal fibroblasts (CFs) is regulated by the presence of the other cell type in a coculture system. In this study, the effect of corneal epithelial cells on the expression of matrix metalloproteinases (MMPs) in CFs was studied. METHODS: Human CFs and simian virus 40-transformed human corneal epithelial (HCE) cells were cultured on opposite sides of a collagen vitrigel membrane. Expression of MMPs in CFs was examined by reverse transcription-polymerase chain reaction and immunoblot analyses. RESULTS: The amounts of MMP-2 mRNA and protein in CFs were decreased by the presence of HCE cells. HCE cells had no effect on the expression of MMP-1 in CFs. HCE cells released interleukin (IL)-1 receptor antagonist (IL-1RA) into the culture medium, and depletion of IL-1RA in HCE cells by RNA interference largely abolished the effect of these cells on MMP-2 expression in CFs. The downregulation of MMP-2 expression in CFs by HCE cells was blocked by an inhibitor of signaling by the mitogen-activated protein kinase (MAPK) ERK (PD98059) but was not affected by those of signaling by the MAPKs p38 (SB203580) or JNK (SP600125). CONCLUSIONS: Corneal epithelial cells downregulated expression of MMP-2 in CFs in a manner dependent at least in part on the release of IL-1RA from the former cells. This effect might contribute to the attenuation of corneal stromal remodeling by corneal epithelial cells.
PURPOSE: The authors previously showed that the expression of various junctional proteins in corneal epithelial cells or corneal fibroblasts (CFs) is regulated by the presence of the other cell type in a coculture system. In this study, the effect of corneal epithelial cells on the expression of matrix metalloproteinases (MMPs) in CFs was studied. METHODS:Human CFs and simian virus 40-transformed human corneal epithelial (HCE) cells were cultured on opposite sides of a collagen vitrigel membrane. Expression of MMPs in CFs was examined by reverse transcription-polymerase chain reaction and immunoblot analyses. RESULTS: The amounts of MMP-2 mRNA and protein in CFs were decreased by the presence of HCE cells. HCE cells had no effect on the expression of MMP-1 in CFs. HCE cells released interleukin (IL)-1 receptor antagonist (IL-1RA) into the culture medium, and depletion of IL-1RA in HCE cells by RNA interference largely abolished the effect of these cells on MMP-2 expression in CFs. The downregulation of MMP-2 expression in CFs by HCE cells was blocked by an inhibitor of signaling by the mitogen-activated protein kinase (MAPK) ERK (PD98059) but was not affected by those of signaling by the MAPKs p38 (SB203580) or JNK (SP600125). CONCLUSIONS: Corneal epithelial cells downregulated expression of MMP-2 in CFs in a manner dependent at least in part on the release of IL-1RA from the former cells. This effect might contribute to the attenuation of corneal stromal remodeling by corneal epithelial cells.