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Shinwu Jeong, M. Elizabeth Fini; Hyperosmotic Stress And Tnf-α Interact To Alter Gene Expression Patterns Associated With Ocular Surface Inflammation In Corneal Epithelial Cells. Invest. Ophthalmol. Vis. Sci. 2012;53(14):563.
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© ARVO (1962-2015); The Authors (2016-present)
Hyperosmotic stress (HOS) stimulates inflammation at the ocular surface, and is thought to be a central mechanism leading to dry eye disease. We addressed the role of osmotic stress and inflammation roles affecting the ocular surface.
We exposed human corneal limbal epithelial cell line to HOS by increasing the NaCl concentration up to 100mM in the cell culture media and to inflammatory stress by adding the proinflammatory cytokines TNF-α and IL-β, each at10 ng/ml, individually or in combination. After treatments, we examined the effects of these agents on cell proliferation using FACS analysis and Western blotting. We also examined effects on expression of a panel of genes involved in ocular surface homeostasis and disease, including cytokines, matrix metalloproteinases (MMPs), and mucins, using semi-quantitative RT-PCR.
HOS altered cell proliferation by increasing the time cells spent at the G2/M phase while also decreasing the time spent in the G0/G1 phase in a NaCl concentration-dependent manner. HOS stimulated phosphorylation of the protein kinase JNK2, but not JNK1, while at the same time it reduced phosphorylation of both ERK1 and ERK2. Treatment with TNF-α did not change the phosphorylated states of any of these kinases regardless of the osmolarity of the media. TNF-α alone stimulated a 2-22-fold increase in expression of most cytokine and MMP genes tested, while HOS had little effect on expression of these genes, or even suppressed their expression. When used to treat cells in combination, HOS and TNF-α acted antagonistically in regulating the expression of IL-1β, IL-8, TGF-β1, MMP-1, -2, -7, and -9, and clusterin, but they acted synergistically in stimulating IL-6 and TNF-α. HOS and TNF-α individually decreased TGF-β2 and MUC16 expression, but the effect of their combined treatment was similar to individual treatments. IL-1β stimulated expression of TNF-α more under HOS conditions.
The current data indicate that HOS and cytokines modulate one another’s effects on gene regulation, suggesting that the role of the HOS condition is to change the environment for the inflammatory process mediated by cytokines.
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