Abstract
Purpose: :
Transforming growth factor-beta2 (TGF-β2) and oxidative stress may be involved in the pathogenesis of glaucomatous optic nerve damage. Histological studies have previously demonstrated increased expression of small heat shock proteins (Hsps) in reactive optic nerve head (ONH) astrocytes of glaucoma patients. The goal of the present study was to determine the effects of TGF-β2 and oxidative stress on the expression of Hsp32, Hsp47, Hsp60, and Hsp70 in cultured human ONH astrocytes.
Methods: :
Cultured ONH astrocytes were treated with 1.0 ng/ml TGF-β2 for 2, 4, 6, 12, 24, and 48 hours, respectively. Additionally, cells were exposed to 100, 200, and 400 µM hydrogen peroxide (H2O2) for 1 hour. Expressions of Hsp32, Hsp47, Hsp60, and Hsp70 were examined by immunohistochemistry, RT-PCR analyses and western-blotting.
Results: :
Treatment with TGF-β2 increased Hsp32 after 2, 4, and 6 hours, whereas Hsp47 was upregulated by TGF-β2 treatment for 12, 24, and 48 hours. Exposure of cells to H2O2 could increase both Hsp32 and Hsp47. No significant effects on the expression of Hsp60 and Hsp70 were observed after treatment of cells with both TGF-β2 and H2O2.
Conclusions: :
TGF-β2 and oxidative stress could increase the expression of Hsp32 and Hsp47, but had no effects on Hsp60 and Hsp70 levels in cultured human ONH astrocytes. These results may provide further insights into the role of heat shock proteins in glaucomatous optic nerve changes.
Keywords: astrocytes: optic nerve head • chaperones • optic nerve