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D-Q Li, Z Chen, XJ Song, W Farley, SC Pflugfelder; Hyperosmolarity Stimulates Production of MMP-9, IL-1ß and TNF- by Human Corneal Epithelial Cells Via a c-Jun NH2-terminal Kinase Pathway . Invest. Ophthalmol. Vis. Sci. 2002;43(13):1981.
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Purpose: To evaluate the expression of c-Jun NH2-terminal kinase (JNK) stress-activated protein kinase, matrix metalloproteinase, MMP-9, and the inflammatory cytokines, IL-1ß and TNF-α, in human corneal epithelial cells (HCE) in response to hyperosmotic stress. Methods: Primary human corneal epithelial cells cultured in normal osmolar media (312 mOsM) were switched to media with 100, 150, or 200 mOsM higher osmolarity by added NaCl, with or without 20 µM SB202190, an inhibitor of the JNK pathway. The media were collected after a 24-hour treatment and used for gelatin zymography and IL-1ß ELISA. Total RNA was extracted from cultures treated for 4 hours and subjected to RT-PCR. The cells treated for 5, 15, or 60 min were lysed in RIPA buffer and subjected to Western blot with phospho-specific JNK antibody. Results: The concentrations of MMP-9 and IL-1ß proteins in the supernatants of HCE exposed to 400-500 mOsM for 24 hours were significantly increased (P<0.05) compared to culture exposed to 312 mOsM. With GAPDH as a control, semi-quantitative RT-PCR disclosed the upregulation of MMP-9, IL-1ß and TNF-α transcripts. Active JNK-1 and JNK-2 were detected by Western blot as early as 5 min after expose of HCE cells to a 450-mOsM environment, and their expression increased with longer exposure times of 15 and 60 min. The JNK inhibitor SB202190 almost completely inhibited the stimulated production of JNK-1 and JNK-2, as well as MMP-9 and IL-1ß, at both mRNA and protein levels, in HCE cells exposed to a hyperosmotic stress. Conclusion: Hyperosmotic stress stimulates expression and production of MMP-9, IL-1ß and TNF-α by HCE that is regulated at least in part by activation of the JNK stress-activated protein kinase pathway. These findings may have implications for the pathogenesis of the ocular surface inflammation that develops in dry eye.
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