Effect of Prostaglandin Analogues on Hyaluronan Production of Orbital Fibroblasts

Background: In thyroid eye disease (TED) pathogenesis, a major contributor is hyaluronan (HA) overproduction by orbital fibroblasts (OF). TED patients often receive prostaglandin analogues (PGA) for elevated intraocular pressure. Their direct effects on OFs, however, remain unclear. Methods: OFs were established from connective tissues obtained from TED patients (n = 4) and non-TED controls (n = 4) during orbital surgeries. HA levels in primary OF culture media, and in the OFs’ pericellular coat, were measured by ELISA. Cultures were performed with or without platelet-derived growth factor BB (PDGF-BB) stimulation, and treated for 72 h with 40 µM prostaglandin F2α (PGF2α), latanoprost, bimatoprost or tafluprost. mRNA expressions of HA synthases (HAS1, HAS2, HAS3) and HA-degrading enzymes (HYAL1, HYAL2, CEMIP) were quantified by RT-PCR. Proliferation and metabolic activity were analysed using BrdU incorporation and MTT assays. Results: PGF2α and each PGA reduced HA levels in the pericellular coat (p < 0.001), while only PGAs reduced HA concentration in the culture medium. Tafluprost and latanoprost suppressed PDGF-BB-stimulated HA synthesis to or below unstimulated levels, respectively (p < 0.001). Latanoprost markedly decreased HAS2 mRNA expression (p < 0.001), even under PDGF-BB stimulation (p < 0.001). PGF2α and each PGA increased CEMIP mRNA expression (p < 0.001). Latanoprost decreased fibroblast proliferation and metabolic activity with and without PDGF-BB stimulation (p < 0.05). Conclusions: These in vitro findings suggest that PGAs modulate HA turnover in orbital fibroblasts through reduced HA synthesis and potentially enhanced degradation. While these observations are confined to cultured cells, they offer a hypothesis for potential clinical relevance in TED, which requires further in vivo validation.