Association of fibroblast growth factor 10 with the fibrotic and inflammatory pathogenesis of Graves' orbitopathy.

Sun Young Jang,Jin Sook Yoon,Eun Jig Lee,Soo Hyun Choi,Don Kikkawa,Dimitrios Karamichos

doi:10.1371/journal.pone.0255344

Abstract

PurposeThe role of fibroblast growth factor (FGF) in orbital fibroblasts (OFs) is rarely known. In this study, we investigated the effect of FGF10 on fibrosis and the inflammation mechanism of Graves′ orbitopathy (GO).MethodsOrbital tissue from GO (n = 15) and non-GO (n = 15) was obtained for this study. The mRNA and protein expression levels of FGF10 and FGF receptor 2b (FGFR2b) in orbital tissue were determined by real-time polymerase chain reaction, western blot analysis, and confocal microscopy. The effects of FGF10 on transforming growth factor (TGF)-β1 induced fibrotic proteins and interleukin (IL)-1β- or tumor necrosis factor (TNF)-α- induced inflammatory proteins were investigated using recombinant human (rh) FGF10 and small interfering (si) RNA transfection against FGF10.ResultsFGF10 and FGFR2b mRNA expression levels were significantly lower in GO orbital tissues than in non-GO orbital tissues (p = 0.009 and 0.005, respectively). Immunostaining of FGF10 in orbital adipose tissues showed differences in FGF10 expression between GO and control samples. Immunostaining of FGF10 was very weak in the orbital tissues of GO patients. TGF-β1-induced fibronectin, collagen Iα, α-smooth muscle actin protein expression in GO OFs was attenuated by rhFGF10 treatment and increased by knockdown of FGF10 via siFGF10 transfection. Similarly, IL-1β- or TNF-α-induced IL-6, IL-8, and cyclooxygenase-2 protein production in GO OFs was either blocked by rhFGF10 treatment or further upregulated by inhibition of FGF10 via siFGF10 transfection.ConclusionsOur data demonstrate that FGF10 has beneficial effects on the inflammatory and fibrotic mechanisms of GO in primary cultured OFs, providing new insights into GO pathology and the discovery of FGF10 as a promising novel therapeutic application for the treatment of GO.

Highlights

Graves0 orbitopathy (GO) is an inflammatory autoimmune disease of the extraocular muscles and orbital fat or connective tissue, generally observed in patients with Graves’ disease [1]
FGF10 and FGF receptor 2b (FGFR2b) mRNA expression levels were significantly lower in GO orbital tissues than in non-GO orbital tissues (p = 0.009 and 0.005, respectively)
transforming growth factor (TGF)-β1-induced fibronectin, collagen Iα, α-smooth muscle actin protein expression in GO orbital fibroblasts (OFs) was attenuated by rhFGF10 treatment and increased by knockdown of FGF10 via siFGF10 transfection

Summary

Introduction

Graves0 orbitopathy (GO) is an inflammatory autoimmune disease of the extraocular muscles and orbital fat or connective tissue, generally observed in patients with Graves’ disease [1]. The pathogenesis of GO remains unclear, orbital fibroblasts (OFs) play a key role in the disease process. OFs express the thyroid-stimulating hormone receptor (TSHR) and activation of the OFs by inflammatory mediators and stimulatory autoantibodies directed against the TSHR and insulin-like growth factor-1 receptor enhance inflammation, hyaluronic acid production, adipogenesis, and fibrosis in GO patients [2, 3]. The roles of FGFs in OFs are rarely known, basic FGF (FGF2) has been proposed to contribute to GO [2, 10, 11]. FGF7, known as a keratinocyte growth factor-1 (KGF1) and FGF10 (KGF2), interacts with one of the FGF receptors (FGFRs), expressed by epithelial cells, and may serve as a protective factor for epithelial tissue

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