Abstract
PurposeTransdifferentiation of human Tenon fibroblasts to myofibroblasts and subsequent deposition of extracellular matrix is a key step in the scarring after glaucoma filtration surgery. The p38 signaling pathway plays an important role in cell proliferation and differentiation, and its upstream regulators and downstream molecules are widely distributed in the eye. We aimed to investigate the role of p38 in the activation of Tenon fibroblasts and that of the anti-fibrotic mechanism of rosiglitazone in the modulation of the p38 signaling pathway.MethodsCultured Tenon fibroblasts were stimulated with transforming growth factor (TGF)-β1. Activation of p38 was examined by western blot analysis. Rosiglitazone and blocking of the p38 signaling pathway by SB203580 were used to antagonize stimulation by TGF-β1. Fibroblast motility was examined by wound closure assay; alpha-smooth muscle actin, connective tissue growth factor, and collagen type I were determined by qPCR and western blot. Expression and localization of alpha-smooth muscle actin were determined by immunofluorescence staining.ResultsPhosphorylated p38 was upregulated in fibroblasts stimulated with TGF-β1, and this effect was substantially inhibited by rosiglitazone. Proliferation and migration of fibroblasts were suppressed by rosiglitazone and SB203580. Expression of alpha-smooth muscle actin, connective tissue growth factor, and collagen type I were decreased at the mRNA and protein levels by rosiglitazone and SB203580. However, the inhibitory effect of SB203580 on transcription and protein expression was weaker than that of rosiglitazone. Similar phenomena were found on immunofluorescence microscopy of alpha-smooth muscle actin.ConclusionsThe p38 signaling pathway mediates the TGF-β1-induced transdifferentiation of human Tenon fibroblasts to myofibroblasts. Rosiglitazone can exert anti-fibrotic activity by interfering with the TGF-β/p38 signaling pathway and might be useful for modulating scar formation after glaucoma filtration surgery.
Highlights
Postoperative scarring is the most common reason for failure of glaucoma filtration surgery
The aim of this study is to investigate the role of p38 mitogen-activated protein kinase (MAPK) in the activation of Tenon fibroblasts and anti-fibrotic mechanism of rosiglitazone in the modulation of the Transforming growth factor (TGF)-b/p38 signaling pathway
The final concentration of dimethyl sulfoxide (DMSO) in medium was less than 0.1%, and Dulbecco modified Eagle medium (DMEM) with 0.1% DMSO was used as vehicle control
Summary
Postoperative scarring is the most common reason for failure of glaucoma filtration surgery. The transdifferentiation of human Tenon fibroblasts to myofibroblasts and subsequent deposition of extracellular matrix are key steps in the scarring of the filtration passage. The persistence of myofibroblasts, characterized by synthesis of a-smooth muscle actin (a-SMA), leads to hypertrophic scar formation and obstruction of the filtration passage. Transforming growth factor (TGF)-b is a key mediator of the transdifferentiation of fibroblasts to myofibroblasts [1,2]. TGF-b is involved in a variety of biological actions, such as cell differentiation, osteogenesis, hematopoiesis, and inflammatory reaction [3]. Blocking of TGF-b may suppress the immune response and hinders wound healing. Blocking of fibrosis-associated TGF-b signal transduction pathways [4,5] may be a safe and effective way to regulate postoperative scarring
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