Gene Suppression of the Chloride Channel 2 Suppressed TGF-β1-Induced Proliferation, Collagen Synthesis, and Collagen Gel Contraction Mediated by Conjunctival Fibroblasts

Abstract

Background: Excessive scarring of filtering blebs is the main cause of surgical failure in glaucoma. Previous studies have highlighted the role of chloride channels (ClCs) in scar formation, whereas the role of ClCs in scarring of filtering blebs has not been studied. Objectives: The objective of this study was to investigate the effects of the chloride channel 2 (ClC-2) on scar formation of filtering blebs after glaucoma filtering surgery. Methods: ClC-2 siRNA-transfected human conjunctival fibroblasts (HConFs) were cultured in type 1 collagen gels in the presence of transforming growth factor (TGF)-β1. Collagen gel contraction was evaluated based on the gel area. 3D-cultured HConFs were treated with the ClC blocker NPPB in the presence of TGF-β1, and cell proliferation collagen synthesis and contractility were measured. The expression levels of matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) in HConFs were assessed by Western blotting and qPCR. Results: TGF-β1 induced cell proliferation, cell cycle progression, collagen synthesis, and collagen gel contraction in HConFs. TGF-β1 increased MMP-2 and MMP-9 levels but inhibited the expression of TIMPs. NPPB and ClC-2 siRNA transfection inhibited TGF-β2-induced cell proliferation, cell cycle progression, collagen synthesis, and collagen gel contraction, mediated by HConFs. TGF-β2-induced increases in MMP-2 and MMP-9 were also inhibited by NPPB and ClC-2 siRNA transfection, but TIMP expression was increased by NPPB and ClC-2 siRNA transfection. Conclusions: These findings demonstrate that ClC-2 ClCs modulate TGF-β1-induced cell proliferation, collagen synthesis, and collagen gel contraction of HConFs by attenuating MMP-2 and MMP-9 production and by stimulating TIMP1 production. NPPB may therefore prove to be of clinical value for the inhibition of scar formation of filtering blebs.