PRL-1 overexpressed placenta-derived mesenchymal stem cells suppress adipogenesis in Graves' ophthalmopathy through SREBP2/HMGCR pathway.

Background: Graves' ophthalmopathy (GO) is a disorder, in which orbital connective tissues get in inflammation and increase in volume. Stimulants such as thyroid-stimulating hormone (TSH), insulin-like growth factor 1(IGF-1), IL-1, interferon γ, and platelet-derived growth factor cause differentiation into adipocytes of orbital fibroblasts (OFs) in the orbital fat and extraocular muscles. Human placental mesenchymal stem cells (hPMSCs) are known to have immune modulation effects on disease pathogenesis. Some reports suggest that hPMSCs can elicit therapeutic effects, but to date, research on this has been insufficient. In this study, we constructed PRL-1 overexpressed hPMSCs (hPMSCs) in an attempt to enhance the suppressive function of adipogenesis in GO animal models.

Methods: In order to investigate the anti-adipogenic effects, primary OFs were incubated with differentiation medium for 10 days. After co-culturing with hPMSCs, the characteristics of the OFs were analyzed using Nile red stain and quantitative real-time polymerase chain reaction. We then examined the in vivo regulatory effectiveness of hPMSCs in a GO mouse model that immunized by leg muscle electroporation of pTriEx1.1Neo-hTSHR A-subunit plasmid. Human PMSCs injection was performed in left orbit. We also analyzed the anti-adipogenic effects of hPMSCs in the GO model.

Results: We found that hPMSCs inhibited adipogenic activation factors, specifically PPARγ, C/EBPα, FABP4, SREBP2, and HMGCR, by 75.1%, 50%, 79.6%, 81.8%, and 87%, respectively, compared with naïve hPMSCs in adipogenesis-induced primary OFs from GO. Moreover, hPMSCs more effectively inhibited adipogenic factors ADIPONECTIN and HMGCR by 53.2% and 31.7%, respectively, than hPMSCs, compared with 15.8% and 29.8% using steroids in the orbital fat of the GO animal model.

Conclusion: Our findings suggest that hPMSCs would restore inflammation and adipogenesis of GO model and demonstrate that they could be applied as a novel treatment for GO patients.