JNK and p38 Inhibitors Prevent Transforming Growth Factor-β1-Induced Myofibroblast Transdifferentiation in Human Graves’ Orbital Fibroblasts

• Published in: International journal of molecular sciences Vol. 22; no. 6; p. 2952
• Main Authors: Hou, Tzu-Yu, Wu, Shi-Bei, Kau, Hui-Chuan, Tsai, Chieh-Chih
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 14.03.2021; MDPI
• Subjects: Actins - genetics; Cell cycle; Cell Transdifferentiation - genetics; Cells, Cultured; Connective Tissue Growth Factor - genetics; Fibroblasts; Fibroblasts - drug effects; Fibroblasts - metabolism; Fibronectins - genetics; Gene Expression Regulation, Developmental - drug effects; Growth factors; Humans; Investigations; Kinases; MAP Kinase Kinase 4 - genetics; Metabolism; Myofibroblasts - drug effects; p38 Mitogen-Activated Protein Kinases - genetics; Pathogenesis; Phosphorylation; Phosphorylation - drug effects; Physiology; Proteins; Pulmonary fibrosis; Transforming Growth Factor beta1 - genetics; Transforming Growth Factor beta1 - pharmacology; mitogen-activated protein kinase; Graves’ ophthalmopathy; Graves’ orbital fibroblasts; c-Jun N-terminal kinase; transforming growth factor-β1; p38
• ISSN: 1422-0067; 1661-6596; 1422-0067
• DOI: 10.3390/ijms22062952

Transforming growth factor-β1 (TGF-β1)-induced myofibroblast transdifferentiation from orbital fibroblasts is known to dominate tissue remodeling and fibrosis in Graves’ ophthalmopathy (GO). However, the signaling pathways through which TGF-β1 activates Graves’ orbital fibroblasts remain unclear. This study investigated the role of the mitogen-activated protein kinase (MAPK) pathway in TGF-β1-induced myofibroblast transdifferentiation in human Graves’ orbital fibroblasts. The MAPK pathway was assessed by measuring the phosphorylation of p38, c-Jun N-terminal kinase (JNK), and extracellular-signal-regulated kinase (ERK) by Western blots. The expression of connective tissue growth factor (CTGF), α-smooth muscle actin (α-SMA), and fibronectin representing fibrogenesis was estimated. The activities of matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) responsible for extracellular matrix (ECM) metabolism were analyzed. Specific pharmacologic kinase inhibitors were used to confirm the involvement of the MAPK pathway. After treatment with TGF-β1, the phosphorylation levels of p38 and JNK, but not ERK, were increased. CTGF, α-SMA, and fibronectin, as well as TIMP-1 and TIMP-3, were upregulated, whereas the activities of MMP-2/-9 were inhibited. The effects of TGF-β1 on the expression of these factors were eliminated by p38 and JNK inhibitors. The results suggested that TGF-β1 could induce myofibroblast transdifferentiation in human Graves’ orbital fibroblasts through the p38 and JNK pathways.