TGF-β2- and H2O2-Induced Biological Changes in Optic Nerve Head Astrocytes Are Reduced by the Antioxidant Alpha-Lipoic Acid

Abstract

Background/Aims: The goal of the present study was to determine whether transforming growth factor-β₂ (TGF-β₂)- and oxidative stress-induced cellular changes in cultured human optic nerve head (ONH) astrocytes could be reduced by pretreatment with the antioxidant α-lipoic acid (LA). Methods: Cultured ONH astrocytes were treated with 1.0 ng/ml TGF-β₂ for 24 h or 200 µM hydrogen peroxide (H₂O₂) for 1 h. Lipid peroxidation was measured by a decrease in cis-parinaric acid fluorescence. Additionally, cells were pretreated with different concentrations of LA before TGF-β₂ or H₂O₂ exposure. Expressions of the heat shock protein (Hsp) αB-crystallin and Hsp27, the extracellular matrix (ECM) component fibronectin and the ECM-modulating protein connective tissue growth factor (CTGF) were examined with immunohistochemistry and real-time PCR analysis. Results: Both TGF-β₂ and H₂O₂ increased lipid peroxidation. Treatment of astrocytes with TGF-β₂ and H₂O₂ upregulated the expression of αB-crystallin, Hsp27, fibronectin and CTGF. Pretreatment with different concentrations of LA reduced the TGF-β₂- and H₂O₂-stimulated gene expressions. Conclusion: We showed that TGF-β₂- and H₂O₂-stimulated gene expressions could be prevented by pretreatment with the antioxidant LA in cultured human ONH astrocytes. Therefore, it is tempting to speculate that the use of antioxidants could have protective effects in glaucomatous optic neuropathy.