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OA Agapova, W-H Wang, BI Weinstein, AF Clark, MR Hernandez; 3 -Hydroxysteroid Dehydrogenase (3 -HSD) Expression in Astrocytes from Normal and Glaucomatous Human Optic Nerve Head (ONH) . Invest. Ophthalmol. Vis. Sci. 2002;43(13):4053.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Using microarray analysis we demonstrated increased expression of 3α -HSD mRNA in cultured glaucomatous ONH astrocytes. 3α -HSDs are aldo-keto reductases (AKR) that metabolize steroid hormones. Four isoforms (AKR1C1-AKR1C4) are encoded by different genes and demonstrate specific tissue distribution. In this study we confirmed and characterized differential expression of mRNA and protein for 3α -HSD isoforms in normal and glaucomatous ONH astrocytes in culture and tissue. Methods: Quantitative real time RT-PCR (Q-PCR) with isoform specific primers and probes was performed to determine isoforms differentially expressed in ONH astrocytes. Western blot and immunostaining were used to determine 3α -HSD protein expression in cells and tissue. Results: Human ONH astrocytes expressed mRNA for three isoforms of 3α -HSD (AKR1C1-AKR1C3). Q-PCR demonstrated that AKR1C1 is the predominant isoform expressed in cultured cells and tissue. Expression of AKR1C1, AKR1C2 and AKR1C3 mRNA was significantly higher in cultured glaucomatous ONH astrocytes than in normal. Lymphocytes from normal and glaucoma donors expressed predominantly AKR1C3 and no diagnosis-related difference in mRNA levels was found. 3α -HSD detection by Western blot demonstrated higher protein levels in glaucomatous astrocytes versus normal. In glaucomatous ONH tissues, intense 3α -HSD immunoreactivity co-localized to GFAP in astrocytes of the lamina cribrosa but not in normals. Conclusion: Glaucomatous ONH astrocytes expressed higher levels of 3α -HSD (AKR1C1) both in vivo and in vitro. The increased expression was tissue-cell specific suggesting that steroid metabolism might be altered in the glaucomatous ONH. This work is the first demonstration that ONH astrocytes can synthesize and/or metabolize steroids in glaucoma, providing a possible link between steroid sensitivity in the trabecular meshwork and glaucomatous optic neuropathy.
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