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G. Sosne, M.K. Wheater, P. Qiu; Thymosin Beta 4 Decreases IL–8 Secretion and Nuclear Nf–B Expression in Cultured Human Corneal Epithelial Cells . Invest. Ophthalmol. Vis. Sci. 2006;47(13):4378.
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© ARVO (1962-2015); The Authors (2016-present)
The purpose of this study was to investigate the ability of thymosin beta 4 (Tß4 ) to regulate interleukin (IL)–8 and nuclear factor kappa B (NF–ΚB) expression in human corneal epithelial cells after stimulation with tumor necrosis factor alpha (TNF–α).
Corneal epithelial cells were cultured in a defined serum–free medium to approximately 80% confluence. After 24 hours culture in medium devoid of any supplements cells were treated, in the presence or absence of Tß4 (1 µg/ml), with TNF–α (10 ng/ml) for 1, 3, 6, and 24 hours. Controls included cells incubated in medium only (with no supplements) and cells incubated with Tß4 only. At each time point culture supernatant was collected for IL–8 ELISA (Quantikine human IL–8 ELISA kit, R&D Systems, Minneapolis, MN). Nuclear lysates were prepared for nuclear p65 NF–ΚB ELISA using an NF–ΚBp65 (total) ELISA kit (BioSource, Camarillo, CA).
In human corneal epithelial cells treated with TNF–α, levels of secreted IL–8 were significantly increased compared to untreated controls at all assay times. Tß4 treatment resulted in a significant decrease in TNF–α–induced IL–8 secretion at later time points in culture. TNF–α additionally caused a significant increase in nuclear NF–ΚBp65 levels compared to untreated controls. Similar to the results observed for IL–8 secretion, Tß4 treatment resulted in a significant decrease in nuclear NF–ΚBp65 levels at later time points in culture.
We have previously shown that Tß4 has anti–inflammatory properties in corneal epithelium. The novel results presented here suggest that Tß4 exerts its anti–inflammatory effects by decreasing IL–8 expression. The decreased nuclear NF–ΚBp65 levels following Tß4 treatment suggests that its anti–inflammatory properties may work through NF–ΚB signaling pathways. These proposed mechanisms of action may be related to the ability of Tß4 to successfully down regulate a number of key pro–inflammatory cytokines and chemokines and decrease PMN infiltration after corneal injury. We propose that Tß4 promotes corneal wound repair by modulating the inflammatory response.
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