2'-O-Galloylhyperin Prevents Tissue Remodeling in Thyroid Eye Disease: Prospects as a Thyrotropin Receptor Antagonist

Thyroid eye disease (TED) is a challenging condition owing to relentless orbital tissue remodeling, with thyrotropin receptor (TSHR) in orbital fibroblasts (OFs) serving as a promising therapeutic target.

This study seeks to discover potential TSHR inhibitors among US Food and Drug Administration (FDA)-approved drugs and evaluate their effects on TED-OFs.

Adipose tissues were sourced from the patients with or without TED. Isolated OFs were cultivated in proliferation medium or stimulated for adipogenic/fibrotic differentiation in 2-dimensional/3-dimenstional models, treated with 2'-O-galloylhyperin (2'-O-GH) (0, 5, 20, and 50 μM). Using structure-based virtual screening (SBVS), potential TSHR antagonists were identified. Cellular proliferation was analyzed by 5-ethynyl-2'-deoxyuridine (EdU) incorporation, flow cytometry, and spheroid size. Adipogenesis was determined by Oil Red O staining, Western blot, and immunofluorescence (IF). Fibrosis was assessed using wound-healing assays, Western blot and IF. Cyclic adenosine monophosphate (cAMP), hyaluronan (HA), and cytokine were quantified by enzyme-linked immunosorbent assay.

Herein, the FDA-approved drug 2'-O-GH dose-dependently decreased cAMP production and the subsequent cAMP-response element binding protein (CREB) phosphorylation stimulated by a TSHR-stimulating monoclonal autoantibody M22, which was reversed by a consistently activated mutation of TSHR (L629F). As expected, 2'-O-GH attenuated lipid accumulation in TED-OFs, along with downregulation of key adipogenic markers, and 2'-O-GH ameliorated HA production during adipogenesis. Notably, 2'-O-GH dampened wound closure and fibrotic differentiation of TED-OF stimulated by transforming growth factor beta 1. Correspondingly, proliferation of TED-OFs was halted by 2'-O-GH.

2'-O-GH is promising for prevention of tissue remodeling of TED by exerting inhibitory effects on proliferation, differentiation, and HA deposition by inhibiting TSHR activation, implying its potential therapeutic value for TED.