Tetramethylpyrazine Attenuates Transdifferentiation of TGF-β2-Treated Human Tenon's Fibroblasts

PURPOSE. To investigate the pharmacologic effect of tetramethylpyrazine (TMP) on human Tenon's fibroblasts (HTFs), the cells implicated in scarring after filtration surgery. METHODS. Transforming growth factor-beta 2 (TGF-beta 2) was used to stimulate a fibrotic phenotype in primary HTFs, and the influence of TMP on the fibrotic phenotype was assessed. Cell proliferation and cell cycle regulation were profiled. Immunofluorescence staining tracked proliferating cell nuclear antigen (PCNA) expression. Transwell assays monitored cell migration. Flow cytometry measured TMP toxicity. In addition, in TGF-beta 2-treated HTFs, Western blot and immunofluorescence were employed to assess the expression of alpha-smooth muscle actin (alpha-SMA). The TMP-mediated activity on cytoskeletal arrangements and extracellular matrix (ECM) accumulation in HTFs was evaluated using actin polymerization and Western blot assays. Moreover, TGF-beta-dependent activation of Smad3 and p38 was examined by Western blot analysis. RESULTS. In TGF-beta 2-treated HTFs, TMP reduced proliferation and migration but did not induce apoptosis. Moreover, TMP attenuated expression of a-SMA and suppressed stress fiber formation stimulated by profibrotic cytokine; it also counteracted TGF-beta 2-induced cytoskeletal rearrangements, morphologic changes, and ECM accumulation. Smad3 and p38 mitogen-activated protein kinase (MAPK) signaling were downstream of the TMP-sensitive effect. CONCLUSIONS. Tetramethylpyrazine counteracts TGF-beta 2-mediated myofibroblast transdifferentiation and attenuates ECM component deposition and cell proliferation in HTFs, implicating TMP as a potential antifibrosis agent in glaucoma filtration surgery.