Suppression of TGF-β pathway by pirfenidone decreases extracellular matrix deposition in ocular fibroblasts in vitro

• Published in: PloS one Vol. 12; no. 2; p. e0172592
• Main Authors: Stahnke, Thomas, Kowtharapu, Bhavani S, Stachs, Oliver, Schmitz, Klaus-Peter, Wurm, Johannes, Wree, Andreas, Guthoff, Rudolf Friedrich, Hovakimyan, Marina
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 23.02.2017; Public Library of Science (PLoS)
• Subjects: Actin; Actins - analysis; Actins - genetics; Anatomy & physiology; Anti-Inflammatory Agents, Non-Steroidal - pharmacology; Biology and Life Sciences; Biomedical engineering; Cell culture; Cell growth; Cell proliferation; Cell Proliferation - drug effects; Cells, Cultured; Collagen; Collagen (type I); Cytokines; Cytotoxicity; Extracellular matrix; Extracellular Matrix - drug effects; Extracellular Matrix - genetics; Extracellular Matrix - metabolism; Extracellular Matrix - pathology; Eye surgery; Fibroblasts; Fibroblasts - cytology; Fibroblasts - drug effects; Fibroblasts - metabolism; Fibroblasts - pathology; Fibronectin; Fibronectins - analysis; Fibronectins - genetics; Fibrosis; Gene expression; Gene Expression Regulation - drug effects; Genetic transformation; Glaucoma; Growth factors; Humans; Immunofluorescence; Lasers; Lung diseases; Medicine and Health Sciences; Muscles; Physiology; Proteins; Pyridones - pharmacology; Research and Analysis Methods; Scars; Side effects; Signal transduction; Signal Transduction - drug effects; Signaling; Smooth muscle; Subpopulations; Surgery; Tissues; Transformation; Transforming growth factor; Transforming Growth Factor beta - antagonists & inhibitors; Transforming Growth Factor beta - metabolism; Transforming growth factor-b; Transforming growth factor-b1; Germany
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0172592

In glaucoma surgery, fibrotic processes occur, leading to impairment of liquid outflow. Activated fibroblasts are responsible for postoperative scarring. The transforming growth factor-β (TGF-β) pathway plays a key role in fibroblast function, differentiation and proliferation. The aim of this study was the characterization of the fibrotic potential of two subtypes of primary human ocular fibroblasts and the attempt to inhibit fibrotic processes specifically, without impairing cell viability. For fibrosis inhibition we focused on the small molecule pirfenidone, which has been shown to prevent pulmonary fibrosis by the decrease of the expression of TGF-β1, TGF-β2 and TGF-β3 cytokines. For in vitro examinations, isolated human primary fibroblasts from Tenon capsule and human intraconal orbital fat tissues were used. These fibroblast subpopulations were analyzed in terms of the expression of matrix components responsible for postoperative scarring. We concentrated on the expression of collagen I, III, VI and fibronectin. Additionally, we analyzed the expression of α-smooth muscle actin, which serves as a marker for fibrosis and indicates transformation of fibroblasts into myofibroblasts. Gene expression was analyzed by rtPCR and synthesized proteins were examined by immunofluorescence and Western blot methods. Proliferation of fibroblasts under different culture conditions was assessed using BrdU assay. TGF-β1 induced a significant increase of cell proliferation in both cell types. Also the expression of some fibrotic markers was elevated. In contrast, pirfenidone decreased cell proliferation and matrix synthesis in both fibroblast subpopulations. Pirfenidone slightly attenuated TGF-β1 induced expression of fibronectin and α-smooth muscle actin in fibroblast cultures, without impairing cell viability. To summarize, manipulation of the TGF-β signaling pathway by pirfenidone represents a specific antifibrotic approach with no toxic side effects in two human orbital fibroblast subtypes. We presume that pirfenidone is a promising candidate for the treatment of fibrosis following glaucoma surgery.