Blockade of KCa3.1: A novel target to treat TGF-β1 induced conjunctival fibrosis.

Postoperative conjunctival fibrosis is common in patients after glaucoma filtration surgery. The calcium activated potassium (KCa3.1) channel has been shown to inhibit fibrosis in many non-ocular tissues. However, its potential in treating ocular fibrosis remains unknown. We tested the anti-fibrotic potential of TRAM34, a selective blocker of KCa3.1 channel, in treating conjunctival fibrosis. Primary human conjunctival fibroblast (HCF) cultures derived from donor tissues. Myofibroblasts causing conjunctival fibrosis were generated by growing HCFs in the presence of TGFβ1 for 72 h. KCa3.1 mRNA and protein expression in HCF was examined with PCR and western blot. The anti-fibrotic potential of TRAM34 was examined by measuring fibrotic gene expression with quantitative PCR (qPCR), immunofluorescence, and western blotting in HCFs in ± TGFβ1 (5 ng/ml) and TRAM34 (0-25 μM). The cytotoxicity of Tram34 was analyzed with trypan blue assay and its role in Smad signaling was studied with immunofluorescence. Expression of KCa3.1 mRNA and protein was detected in HCFs and TGFβ1 treatment to HCFs significantly increased expression of KCa3.1. TRAM34 treatment attenuated transcription of fibrotic markers, αSMA (p < .001), fibronectin (p < .05), collagen I (p < .001) and collagen IV (p < .001) in TGFβ1-induced HCFs. Further, TRAM34 significantly inhibited TGFβ1-stimulated αSMA protein expression (p < .01) and nuclear translocation of fibrotic Smad2/3 in HCFs and showed no significant cytotoxicity (p < .05). The KCa3.1 potassium channel plays a significant role in the prevention of conjunctival fibrosis and TRAM34 has potential to control post surgical bleb fibrosis in patients. In vivo studies are warranted.