ABSTRACT
Aim: To study the effects of triamcinolone acetonide (TA) on cultured human trabecular meshwork (HTM) cells. Materials and Methods: HTM cells were cultured and treated with 125, 250, 500 and 1000 μg/mL concentration of TA for 24 h. The cells were treated with both crystalline TA (TA‑C) (commercial preparation) and solubilized TA (TA‑S). Cell viability was measured by a trypan blue dye exclusion test. The activity of caspse‑3/7 was measured by a fluorescence caspase kit and DNA laddering was evaluated by electrophoresis on 3% agarose gel. Levels of lactate dehydrogenase (LDH) were assessed with LDH cytotoxicity assay kit‑II. Results: Mean cell viabilities of HTM cells after 24 h exposure to TA‑C 125, 250, 500, and 1000 μg/mL were 75.4 ±2.45% (P < 0.0001), 49.43 ± 1.85% (P < 0.0001), 17.07 ± 2.39% (P < 0.0001), and 3.7 ± 0.9% (P < 0.0001), respectively, compared with the untreated HTM cells 92.49 ± 1.21%. The mean cell viabilities with 125, 250, 500, and 1000 μg/mL of TA‑S were 94.47 ± 1.60% (P > 0.05), 90.13 ± 0.40% (P < 0.01), 85.57 ± 0.47% (P < 0.001), and 71.67 ± 3.30% (P < 0.0001), respectively, compared to DMSO‑equivalent cultures. Untreated HTM control had a cell viability of 96.57 ± 1.98%. DMSO‑treated controls of 125, 250, 500, and 1000 μg/mL had a cell viability of 94.73 ± 0.57%, 96.97 ± 1.08%, 93.97 ± 1.85%, and 97.27 ± 1.15%, respectively. There was no increase of caspase‑3/7 activity in cultures treated with either TA‑C or TA‑S. DNA laddering showed no bands in the TA‑C or TA‑S treated cultures. There were significantly higher LDH release rates at all concentrations of TA‑C compared to TA‑S. Conclusions: Results show that the effect of TA‑C and TA‑S on HTM cells is due to cell death by necrosis at all concentrations except 125 μg/mL of TA‑S. Elevated levels of LDH confirmed necrotic cell death. Our study also infers the relative safety of TA‑S over TA‑C.
ABSTRACT
Objective Research showed that angiotensin converting enzyme inhibitor and angiotensinⅡ(AngⅡ)receptor antagonist has good role of lowing-intraocular pressure.This study was to explore whether cultured human trabecular meshwork cells express AngⅡin vitro.MethodsThe human trabecular meshwork cells strains were cultured in DMEM+F12 medium containing 25% fetal bovine serum in vitro and passaged at the climbing sheet was prepared.The expression of AngⅡ in human trabecular meshwork cells was examined by immunohistochemistry,and AngⅡ protein was localized by Western blot.ResultsSubcultured cells showed spindle shape.AngⅡwas positively expressed in human trabecular meshwork cells by immunochemistry,showing the yellow-brown granule in cellular membrane and cytoplasm.A absence of response for AngⅡwas found in negative control sample.The band of AngⅡ protein was found at the relative molecular weight of 64 000 by Western blot.ConclusionThe result implies that human trabecular meshwork cells have the ability of synthesizing AngⅡ.It suggests that AngⅡ participates in the regulation of intraocular tension in glaucomous eye.
ABSTRACT
Dexamethasone (DEX), one of the corticosteroid hormones, is one of the most common therapeutic strategies in ophthalmological treatment. Despite its widespread use and clinical efficiency, little is known regarding the specific effects of DEX on cell growth, differentiation and cell death in human trabecular meshwork cells. The presence of the glucocorticoid receptor (GR, dexamethasone receptor) in TM-5 cell line, which was derived from the primary human trabecular meshwork cells, was verified by RT-PCR and western blot analysis. The effects of DEX on the cellular proliferation of TM5 cells were measured by a BrdU incorporation assay. Western blot analysis were used to examine the effects of DEX on the Ras/MEK/ERK signaling pathway. The total Ras, MEK1/2 and ERK1/2 protein levels as well as the levels of activated (phosphorylated) form were both significantly increased by the DEX treatment for 5 days. Both MEK1/2 and ERK1/2 were significantly activated by phosphorylation after 10 minutes. The dependence of this increased cell proliferation on GR activation by DEX and the sustained activation of ERK was examined using RU486 (a GR inhibitor) and U0126 (a MEK inhibitor). Both RU486 and U0126 prevented the induction of cell proliferation by the DEX treatment in the TM5 cells. In conclusion this study demonstrated that GR is expressed in TM5 cells. Secondly, DEX treatment for 5 days stimulates cell proliferation in TM5 cells, and that this increased proliferation effect is mediated by the Ras/MEK/ERK pathway.