Role of the ClC-2 Chloride Channel in TGF-β1-induced Proliferation, Collagen Synthesis, and Collagen Gel Contraction Mediated by Human Conjunctival Fibroblasts

Abstract Background: Excessive scar tissue can reduce postoperative survival of filtering blebs in patients with glaucoma. Previous studies have highlighted the role of chloride channels in wound healing. whereas The role of chloride channels in the formation of follicular scar has not been studied. Objectives: To investigate the effects of the ClC-2 chloride channel on scar formation of filtering blebs after glaucoma filtering surgery. Methods: We Inhibited ClC-2 chloride channels of Human Conjunctival Fibroblasts (HConFs) by transfecting HConFs with ClC-2 siRNA, Then cell proliferation, cycle and collagen synthesis of HConFs were measured. ClC-2 siRNA-transfected HConFs were cultured in type I collagen gels in the presence of transforming growth factor (TGF)-β1. Collagen gel contraction was evaluated based on the gel area. The expression levels of matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) in HConFs were assessed by western blotting and q-PCR. Results: TGF-β1induced 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. ClC-2 siRNA transfection inhibited TGF-β1-induced cell proliferation, cell cycle progression, collagen synthesis, and collagen gel contraction, mediated by HConFs. TGF-β1-induced increases in MMP-2 and MMP-9 were also inhibited by NPPB and ClC-2 siRNA transfection, but TIMP expression was increased by ClC-2 siRNA transfection. Conclusions: These findings demonstrate that ClC-2 gene knockout inhibited TGF-β1-induced cell proliferation, collagen synthesis, and collagen gel contraction of HConFs by attenuating MMP-2 and MMP-9 production and by stimulating TIMP-1 production. Keywords: ClC-2 chloride channel; conjunctival fibroblasts; TGF-β1; wound heal