Suppression of transforming growth factor-β effects in rabbit subconjunctival fibroblasts by activin receptor-like kinase 5 inhibitor

[摘要] Purpose: Transforming growth factor-β(TGF-β) activity has been implicated in subconjunctival scarring ineyes following glaucoma filtration surgery (GFS). The purpose of thisstudy is to determine whether an inhibitor for activin receptor-likekinase (ALK) 5 (also known as TGF-β receptor type I) could suppressTGF-β activity and thereby promote filtering bleb survival after GFS ina rabbit model. Methods: An ALK-5 inhibitor, SB-505124,was used. A docking study was performed to investigate the interactionbetween the inhibitor and the receptor. Immunofluorescence forconnective tissue growth factor (CTGF) and α-smooth muscle actin(α-SMA) was performed in cultured rabbit subconjunctival fibroblasts.Immunoblotting for phosphorylated Smad2 (pSmad2), CTGF, and α-SMA wasalso performed. In an in vivo rabbit GFS model, SB-505124 was deliveredin a lactose tablet during surgery. Eyes were examined by slit-lamp andintraocular pressure (IOP) was measured until the time of bleb failureor up to 28 days after surgery. Tissue sections on day 5 after surgerywere histologically evaluated after staining with hematoxylin andeosin. The sections were also immunostained for CTGF and α-SMA. Inaddition, cell outgrowth from dissected subconjunctival tissues placedin a cell culture flask with media was investigated. Results: The docking study indicatedhydrogen bond interactions between SB-505124 and amino acids His-283and Ser-280 of ALK-5. Suppression of pSmad2, CTGF, and α-SMA bySB-505124 was observed in cultured fibroblasts. Filtering blebs in theGFS with SB-505124 group were maintained for more than 10 days, and theperiod of bleb survival was significantly longer than that in controls.IOP levels after surgery seemed to be related to bleb survival.Histologically, subconjunctival cell infiltration and scarring at thesurgical site in the GFS with SB-505124 and mitomycin C (MMC) groupswere muchsubsided compared to controls. Suppression of CTGF and α-SMA bySB-505124 was also observed by immunofluorescence. Cell outgrowth fromexplants dissected from eyes to which SB-505124 was applied during GFSwas robust while outgrowth was poor from those treated with MMC. Conclusions: The ALK-5 inhibitorSB-505124 was efficacious both in vitro and in vivo in suppressing theTGF-β action. The inhibitor may provide a novel therapy for preventingocular inflammation and scarring.

[学科分类] 生物化学/生物物理