Beneficial Effects Of Hypercapnic Acidosis On The Inhibition Of Transforming Growth Factor Beta-1-Induced Corneal Fibrosis In Vitro

Purpose: Corneal scarring is a common poor outcome of corneal trauma. Transforming growth factor beta-1 plays a vital role in corneal fibrosis, inducing keratocyte transformation to myofibroblasts. Other than corneal transplantation, no other curative treatment methods for corneal scarring are currently available. Hypercapnic acidosis exerts anti-inflammatory and anti-migratory effects on numerous organs; however, its effect on corneal fibroblasts remains unknown. Hence, this study aimed to evaluate the effect of hypercapnic acidosis on transforming growth factor beta-1-induced fibrosis in corneal fibroblasts and to elucidate the underlying mechanisms.Materials and Methods: Corneal fibroblasts were obtained from human limbal tissue and cultured with or without transforming growth factor beta-1 under hypercapnic acidosis or no-hypercapnic acidosis conditions, and subjected to scratch wound, cell migration, and collagen matrix contraction assays. Furthermore, immunocytochemistry was performed to evaluate the alpha-smooth muscle actin stress fiber. Finally, western blotting was performed to assess the expression of proteins in the NF-kappa B and Smad pathways.Results: Hypercapnic acidosis suppressed collagen gel contraction capacity in transforming growth factor beta-1-treated corneal fibroblasts and inhibited transforming growth factor beta-1-induced cell migration. Moreover, hypercapnic acidosis downregulated corneal fibrosis marker alpha-smooth muscle actin in transforming growth factor beta-1-treated corneal fibroblasts. Furthermore, hypercapnic acidosis suppressed transforming growth factor beta-1-induced fibrosis, at least partly, by inhibiting Smad2/3 phosphorylation and down-regulatingp-I kappa B-dependent and RelB signaling transduction.Conclusions: Hypercapnic acidosis inhibits transforming growth factor beta-1-induced corneal fibroblast migration, collagen gel contraction capacity, and alpha smooth muscle actin expression, potentially through the Smad and NF-kappa B pathways. Therefore, hypercapnic acidosis may be a potentially useful anti-fibrotic therapy for corneal scarring.