4-Methylumbelliferone suppresses hyaluronan and adipogenesis in primary cultured orbital fibroblasts from Graves' orbitopathy.

Abstract

In Graves' orbitopathy (GO), hyaluronan secreted by orbital fibroblasts contributes to orbital tissue expansion. The goal of this research was to evaluate the potential benefit of 4-methylumbelliferone (4-MU), a hyaluronan synthase (HAS) inhibitor, in primary cultured orbital fibroblasts from Graves' orbitopathy. We assessed the viability of orbital fibroblasts using a live/dead cell assay. Hyaluronan synthesis was evaluated by enzyme-linked immunosorbent assay (ELISA) and quantitative real-time PCR (qPCR). Adipogenesis was assessed by Oil Red O staining and qPCR of adipogenic transcription factors. In orbital fibroblasts treated with 4-MU (up to 1000μM), cell viability was preserved by 90%. 4-MU significantly inhibited HAS gene expression and hyaluronan production (*P < 0.05). With respect to adipogenesis, 4-MU suppressed the accumulation of lipids and reduced the number of adipocytes, while decreasing expression of adipogenic transcription factors. 4-MU represents a promising new therapeutic agent for GO based on its ability to inhibit hyaluronan production and adipogenesis, without decreasing cell viability.