SAT-421 Novel Role of Chloroquine and Hydroxychloroquine in Graves’ Orbitopathy Therapy by Targeting Orbital Fibroblasts

Abstract: Context: Graves’ orbitopathy (GO) presents with infiltrative exophthalmos due to excessive proliferation, adipogenesis and glycosaminoglycans production of orbital fibroblasts (OFs). There are few therapies potent for proptosis. Intervention in autophagy of OFs could be a potential therapy. Objectives: Here, our purpose was to evaluate the effects of chloroquine (CQ) and its derivative hydroxychloroquine (HCQ), as autophagy inhibitors commonly used in clinical practice, on GO-OFs from human orbit in vitro. Design/Setting/Participants: OFs isolated from patients with GO (n = 10) or control persons (non-GO) (n = 8) were allowed to proliferate in the proliferation medium (PM) or differentiate into adipocytes in the differentiation medium (DM), co-treated with CQ of different concentrations, and subsequently examined in vitro. Main Outcome Measures: CCK-8, EdU incorporation and flow cytometry were used to assess cellular viability. Adipogenesis was assessed by Western blot, real time-PCR, and Oil Red O staining. Hyaluronan was determined by real time-PCR and ELISA. Autophagy flux was detected using RFP-GFP-LC3 fluorescent staining and Western blot. Results: CQ (10μM) or HCQ (10μM) treatment for 48h was sufficient to block autophagy flux without exhibiting cell toxicity in OFs from either GO or non-GO participants. Cellular proliferation of GO-OFs was halted by both CQ and HCQ. Also CQ and HCQ exerted an inhibitory action on lipid accumulation of GO-OFs during differentiation as well as expression of adipogenetic markers such as PPARγ and c/EBP-α/β. Moreover, hyaluronan secretion, concurrent with expression of hyaluronan synthase 2 (HAS2), was obviously decreased by CQ and HCQ. Conclusions: We reported the efficacies of CQ and HCQ on proliferation, adipogenesis and hyaluronan generation of GO-OFs via inhibiting autophagy, providing proof of concept that quinoline-based antimalarial (QBA) drugs like CQ and HCQ have potential to be a new treatment for GO as autophagy inhibitors.