Differential Effects of EP3, FP, and EP2 Receptor Agonists on Orbital Adipogenesis in a 3D Spheroid Model of Thyroid Eye Disease

To compare the differential effects of EP3, FP, and EP2 receptor agonists on adipogenic differentiation in orbital adipose-derived mesenchymal stem cell (OASC) spheroids from thyroid eye disease (TED) patients.
Orbital adipose tissue was obtained from inactive TED patients, and OASCs were isolated. Three-dimensional spheroid cultures were established and induced for adipogenic differentiation in the presence of FP agonist bimatoprost (BIM), EP3 agonist sulprostone (SULP), or EP2 agonist butaprost (BUTA). Spheroid size and lipid accumulation were assessed using bright-field imaging, BODIPY staining, and Oil Red O staining. Gene and protein expression of adipogenic markers (PPARG, ADIPOQ, FABP4, LEPTIN) were quantified by qPCR and/or western blotting. Levels of IL-1, IL-6, TNF-α, IFN-γ, MCP-1, and Leptin in culture supernatants were measured by ELISA.
Sulprostone and bimatoprost markedly inhibited adipogenic differentiation of OASC spheroids, as evidenced by reduced spheroid size, decreased lipid accumulation, and downregulation of PPARG, FABP4, and LEPTIN. Compared with sulprostone, bimatoprost exerted a stronger inhibitory effect, showing smaller spheroid size, fewer lipid droplets, and lower LEPTIN expression. Despite the suppression of lipid accumulation, ADIPOQ expression was significantly upregulated in both SULP and BIM groups. Notably, bimatoprost treatment was associated with increased secretion of IL-6 and TNF-α, whereas sulprostone did not significantly alter the levels of the examined inflammatory cytokines. In contrast, butaprost showed no significant inhibitory effect on adipogenic differentiation, with lipid accumulation patterns similar to those of the control group.
Activation of EP3, FP, and EP2 receptors differentially modulates orbital adipogenesis. Among them, EP3 receptor activation by sulprostone suppresses adipogenic differentiation without increasing the evaluated inflammatory cytokines in our study. These findings suggest that EP3 receptor agonism may represent a potential strategy for limiting orbital fat expansion in TED, although further in vivo studies are required to evaluate its therapeutic feasibility and safety.