RESUMO
OBJECTIVE: To explore the effect of suberoylanilide hydroxamic acid (SAHA) (i) on corneal fibroblast differentiation, morphology, and viability; and (ii) on the expression levels of matrix metalloproteinases (MMPs) 2 and 9 using an in vitro model of equine corneal fibrosis. PROCEDURE: Healthy donor corneas were used to generate primary cultures of equine corneal fibroblasts. The fibroblasts were exposed to 5 ng/mL TGFß1 to induce myofibroblast formation. The cultures were treated with either 5 µm or 10 µm SAHA for 72 h in the presence of TGFß1. Real-time PCR and immunocytochemistry were used to determine the antifibrotic efficacy of SAHA by quantifying α-smooth muscle actin (αSMA), a marker of myofibroblast formation and fibrosis. Real-time PCR was used to determine the effects of SAHA on MMP2 and MMP9 expression. Cytotoxicity of SAHA was evaluated with phase contrast microscopy and trypan blue exclusion assays. RESULTS: Suberoylanilide hydroxamic acid (SAHA) significantly attenuated TGFß1-induced differentiation of equine fibroblasts to myofibroblasts as indicated by 3- to 3.5-fold (P < 0.001) decrease in αSMA mRNA and 86-88% (P < 0.001) decrease in αSMA+ immunocytochemical staining. SAHA treatment also resulted in 4.5- to 5.5-fold (P < 0.01) decrease in MMP9 expression. A dose-dependent bimodal effect of SAHA on MMP2 expression was noted (3.5-fold increase with 5 µm dose; 0.5-fold decrease with 10 µm dose). No change in fibroblast viability was observed with a 5 µm SAHA dose, whereas a 10 µm dose resulted in a moderate 17% decrease in cell viability. CONCLUSIONS: Suberoylanilide hydroxamic acid (SAHA) can effectively inhibit TGFß-induced differentiation of equine corneal fibroblasts to myofibroblasts and modulates MMP production in vitro.
