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D.J. Calkins, R.M. Sappington; Pressure–Induced Production of Inflammatory Cytokines and Activation of NFB Is Modulated by Calcium Channels in Retinal Glia . Invest. Ophthalmol. Vis. Sci. 2005;46(13):3579.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Retinal glial cells produce a wide range of cytokines in the human glaucomatous eye as well as experimental models. In the central nervous system, production of cytokines is regulated by many factors, including transcription factors and calcium (Ca2+) signaling. We examined the contribution of Ca2+ signaling and activation of the transcription factor nuclear factor kappa B (NFΚB) to pressure–induced production of interleukin–6 (IL–6) and tumor necrosis factor alpha (TNFα) by retinal glia in an in vitro model of glaucoma. Methods: We created purified primary cultures of astrocytes and microglia from post–natal rat retina using immunomagnetic separation. We exposed these cultures to elevated hydrostatic pressure for 24 hours in the presence or absence of the Ca2+ chelator EGTA and the Ca2+ channel blocker ruthenium red. We then measured release of IL–6 and TNFα into the culture media using ELISA and evaluated activation and nuclear translocation of NFΚB using immunocytochemistry. Results: We found that elevated pressure decreased production of both IL–6 and TNFα by astrocytes and induced transient activation of NFΚB. Treatment with both EGTA and ruthenium red further decreased IL–6 release, but reversed the pressure–induced decrease in TNFα. In addition, treatment with both EGTA and ruthenium red prolonged the activation of NFΚB at elevated pressure. In microglia, elevated pressure increased both IL–6 and TNFα release, while inducing sustained activation of NFΚB. Treatment with both EGTA and ruthenium red reversed the pressure–induced increase in IL–6 release, but did not alter TNFα release. In addition, treatment with both EGTA and ruthenium red decreased pressure–induced activation and translocation of NFΚB. Conclusions: These data suggest that Ca2+ signaling contributes to the activation of NFΚB and the release of IL–6 and TNFα by retinal glia in response to elevated pressure.
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