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B. A. Pfeffer, C. A. DeWitt, D. Meyer, M. Salvador-Silva, M. Cavet, F. J. López, K. W. Ward; Decreased Myocilin Expression in Cultured Trabecular Meshwork Cells Induced by a Selective Glucocorticoid Receptor Agonist (SEGRA) Suggests an Improved Ocular Safety Profile Versus Steroids. Invest. Ophthalmol. Vis. Sci. 2009;50(13):4075.
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Glucocorticoid receptor (GR) agonists are commonly used in ophthalmology. However, conventional GR agonists such as steroids incur side effects, including elevated intraocular pressure. Steroid-induced glaucoma may be related to excess secretion of myocilin (MYOC), which can accumulate in the trabecular meshwork (TM) and obstruct outflow. Therefore, GR agonists with decreased ability to induce MYOC may offer an improved clinical safety profile compared to steroids. We compared in vitro MYOC expression in TM cells exposed to BOL-303242-X (a selective GR agonist (SEGRA)), dexamethasone (DEX), and prednisolone acetate (PA).
Confluent 2nd/3rd passage monkey TM cell cultures were maintained in 12-well plates in medium supplemented with 10% fetal bovine serum, without added glucocorticoids. Cell strains derived from individual animals were tested separately. TM cells were incubated for 5 days with 3 nM-300 nM BOL-303242-X (SEGRA), DEX, or PA. Following treatment, conditioned media (CM) and cell lysates were harvested. MYOC in CM was assessed by PAGE-Western blot, with quantitative densitometry of specific chemiluminescence. MYOC RNA levels from TM cell lysates were analyzed by quantitative real time RT-PCR using monkey-specific primers.
Under control conditions, TM cells released MYOC protein into CM and also expressed MYOC mRNA. Treatment with DEX or PA elicited dose-dependent increases in MYOC protein and mRNA abundance. BOL-303242-X treatment resulted in lower MYOC expression at all doses, compared to both DEX and PA. When data for MYOC protein were averaged for all TM strains receiving each treatment, the maximal response (estimated Emax) induced by BOL-303242-X was significantly lower than for DEX (3.0- vs. 5.6-fold over control, respectively), while Emax was not significantly different between PA and DEX. Compared to DEX, MYOC mRNA levels were lower for both PA- and BOL-303242-X-treated TM cells.
Novel GR ligands with the anti-inflammatory potency of conventional steroids, but with a more favorable balance of transrepression and transactivation, could minimize ocular adverse events, by limiting expression and accumulation of MYOC in the TM. Since increased MYOC expression may be predictive of IOP increases associated with steroids, our results indicate that BOL-303242-X may offer an improved clinical safety profile.
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