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RUOXI WU, Hanna Bähler, Maren Hennig, Dirk Bauer, Katrin Brockhaus, Solon Thanos, Arnd Heiligenhaus, Carsten Heinz; Influence of proinflammatory cytokines and dexamethasone on human trabecular meshwork cells in vitro under elevated hydrostatic pressures. Invest. Ophthalmol. Vis. Sci. 2014;55(13):5670.
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© ARVO (1962-2015); The Authors (2016-present)
Increased intraocular pressure (IOP) in uveitis patients is a challenging complication. The impact of proinflammatory cytokines together with increased IOP on the acceleration of pathological changes of the human trabecular meshwork (HTM) is unknown. Aim of this study was to examine HTM cell viability treated with cytokines and steroids under hydrostatic pressures.
HTM cells derived from donor corneal rings were cultivated. Cell passages three to six were used. Cells were treated with medium, Tumor Necrosis Factor-alpha (T, 20pg/ml), Interleukin-1alpha (I, 10ng/ml), T+I, Dexamethasone (D, 10μM), D+T, D+I and D+T+I respectively at 37°C in a 5% carbon dioxide atmosphere for 48 hours. Different groups were exposed to 15mmHg and 50mmHg in the pressure chamber which stand for normal and high IOP respectively. A control group was incubated in the incubator. Cell viability was assessed by MTT Assay (8 tests, 7 strains). Cell apoptosis and necrosis were examined by Flow cytometry (14 tests, 8 strains). Apoptosis was detected by Annexin V-PE Apoptosis Detection Kit.
In all conditions, cell viability was markedly reduced by dexamethasone compared to medium (p<0.001). A similar effect was seen when dexamethasone combined with cytokines (T vs D+T, I vs D+I, T+I vs D+T+I, p<0.001). Compared to medium, TNF increased viability only slightly under all conditions while IL showed a significant increase in the control (p=0.033) and in the 15mmHg group (p=0.037); a combination of TNF and IL raised cell viability under 15mmHg (p=0.003) and 50mmHg (p=0.034). Cell viability decreased with increasing pressure. Treatment with Dexamethasone under 50mmHg had significantly lower viability compared to the control (p=0.03). In FACS analysis, dexamethasone showed increased numbers of dead cells, more apoptotic cells, and the largest number of necrotic cells (p=0.025).
Dexamethasone decreased cell viability especially under 50mmHg compared to control and 15mmHg, and lead to higher numbers of apoptotic and necrotic cells. Proinflammatory cytokines increased cell viability. Iatrogenic influence through corticosteroid eye drops may therefore also contribute to the development of secondary uveitic glaucoma by influencing different components of HTM function. This effect seems to be aggravated by increased IOP.
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