Topical Rosiglitazone Is an Effective Anti-Scarring Agent in the Cornea

Abstract

Corneal scarring remains a major cause of blindness world-wide, with limited treatment options, all of which have side-effects. Here, we tested the hypothesis that topical application of Rosiglitazone, a Thiazolidinedione and ligand of peroxisome proliferator activated receptor gamma (PPARγ), can effectively block scar formation in a cat model of corneal damage. Adult cats underwent bilateral epithelial debridement followed by excimer laser ablation of the central corneal stroma to a depth of ∼160 µm as a means of experimentally inducing a reproducible wound. Eyes were then left untreated, or received 50 µl of either 10 µM Rosiglitazone in DMSO/Celluvisc, DMSO/Celluvisc vehicle or Celluvisc vehicle twice daily for 2 weeks. Cellular aspects of corneal wound healing were evaluated with in vivo confocal imaging and post-mortem immunohistochemistry for alpha smooth muscle actin (αSMA). Impacts of the wound and treatments on optical quality were assessed using wavefront sensing and optical coherence tomography at 2, 4, 8 and 12 weeks post-operatively. In parallel, cat corneal fibroblasts were cultured to assess the effects of Rosiglitazone on TGFβ-induced αSMA expression. Topical application of Rosiglitazone to cat eyes after injury decreased αSMA expression and haze, as well as the induction of lower-order and residual, higher-order wavefront aberrations compared to vehicle-treated eyes. Rosiglitazone also inhibited TGFβ-induced αSMA expression in cultured corneal fibroblasts. In conclusion, Rosiglitazone effectively controlled corneal fibrosis in vivo and in vitro, while restoring corneal thickness and optics. Its topical application may represent an effective, new avenue for the prevention of corneal scarring with distinct advantages for pathologically thin corneas.

Inhibitory effects of PPARγ ligands on TGF-β1-induced CTGF expression in cat corneal fibroblasts

“…A solution would be a drug that selectively targets the TGF-β cascade, but with minimal side-effects. Our group and others have shown several ligands of PPARγ to be effective corneal anti-fibrotics in vitro (Jeon et al 2014, Kuriyan et al 2012, Pan et al 2009, Pan et al 2011) and in vivo (Huxlin et al 2013, Jeon et al 2014). PPARγ is a transcription factor belonging to a nuclear receptor superfamily that regulates important cellular functions, including metabolism, adipogenesis, proliferation, differentiation and inflammatory responses (Simpson-Haidaris et al 2010).…”

“…Primary feline corneal keratocytes were isolated as previously described (Huxlin et al 2013, Jeon et al 2014). In brief, fresh corneas were obtained immediately post-mortem from young, adult domestic short-hair cats ( felis cattus ).…”

“…The medium was changed to one containing DMEM/F12 + 1% HS for 1 day in order to promote cellular quiescence. Western blots were used to detect the expression of CTGF and αSMA relative to the expression of β-Tubulin as a loading control, as described previously (Huxlin et al 2013, Jeon et al 2014). Expression of αSMA was used as positive control to indicate myofibroblast differentiation.…”

“…PPARγ is a transcription factor belonging to a nuclear receptor superfamily that regulates important cellular functions, including metabolism, adipogenesis, proliferation, differentiation and inflammatory responses (Simpson-Haidaris et al 2010). A significant body of data suggests that PPARγ ligands can act as anti-fibrotics in a range of body tissues, including lung (Ferguson et al 2009, Lin et al 2010, Zhou et al 2012), skin (Ghosh et al 2004), kidneys (Liu et al 2011) and cornea (Huxlin et al 2013, Jeon et al 2014, Kuriyan et al 2012, Pan et al 2009, Pan et al 2011). In the cornea , two such ligands - Rosiglitazone and Troglitazone – were recently shown effective at control fibrosis after PRK, without significant side-effects (Huxlin et al 2013, Jeon et al 2014).…”

“…A significant body of data suggests that PPARγ ligands can act as anti-fibrotics in a range of body tissues, including lung (Ferguson et al 2009, Lin et al 2010, Zhou et al 2012), skin (Ghosh et al 2004), kidneys (Liu et al 2011) and cornea (Huxlin et al 2013, Jeon et al 2014, Kuriyan et al 2012, Pan et al 2009, Pan et al 2011). In the cornea , two such ligands - Rosiglitazone and Troglitazone – were recently shown effective at control fibrosis after PRK, without significant side-effects (Huxlin et al 2013, Jeon et al 2014). Here, we asked whether PPARγ ligands exert part of their anti-fibrotic actions in the cornea by influencing TGF-β1-induced CTGF expression in stromal fibroblasts - a potentially novel mechanism of action for this promising group of molecules.…”