Characteristics of Hyaluronan Synthesis Inhibition by 4-Methylumbelliferone in Orbital Fibroblasts

Abstract

PURPOSE. Hyaluronan (HA) overproduction by orbital fibroblasts (OFs) is a major factor in the pathogenesis of Graves' orbitopathy (GO). 4-methylumbelliferone (4-MU) is an inhibitor of HA synthesis in different cell types in vitro and has beneficial effects in animal models of autoimmune diseases. METHODS. HA production and mRNA expression of HA synthases (HAS1, HAS2, and HAS3) and hyaluronidases (HYAL1 and HYAL2) were measured in the presence and absence of 4-MU in unstimulated and transforming growth factor-β-stimulated fibroblasts from GO orbital (n = 4), non-GO orbital (n = 4), and dermal origin (n = 4). RESULTS. The 4-MU treatment (1 mM) for 24 hours resulted in an average 87% reduction (P < 0.001) of HA synthesis, decreased the expression of the dominant HAS isoform (HAS2) by 80% (P < 0.0001), and increased the HYAL2 expression by 2.5-fold (P < 0.001) in control OFs, GO OFs, and dermal fibroblasts (DFs) regardless of the origin of the cells. The proliferation rate of all studied cell lines was reduced to an average 16% by 4-MU (P < 0.0001) without any effects on cell viability. HA production stimulated by transforming growth factor-β was decreased by 4-MU via inhibition of stimulated HAS1 expression in addition to the observed effects of 4-MU in unstimulated cases. Characteristics of HA synthesis inhibition by 4-MU did not differ in OFs compared with DFs. CONCLUSIONS. 4-MU has been found to inhibit the HA synthesis and the proliferation rate in OFs in vitro, adding it to the list of putative therapeutic agents in a disease the cure of which is largely unresolved.

Oral administration of 4-methylumbelliferone reduces glial scar and promotes anatomical plasticity

“…2019). Previous work has shown that 4-MU inhibits the production of UDP-glucuronic acid (UDP-GlcA) (Galgoczi et al . 2020), a key substrate for HA production, and the expression of hyaluronan synthases (HASs), UDP-glucose-pyrophosphorylase (an enzyme for the biosynthesis of UDP-glucose) and UDP-glucose-dehydrogenase (an enzyme that converts UDP-glucose into UDP-glucuronic acid (Kakizaki et al .…”

“…4-MU is a known inhibitor to HA synthesis (Nagy et al 2015;Nagy et al 2019). Previous work has shown that 4-MU inhibits the production of UDP-glucuronic acid (UDP-GlcA) (Galgoczi et al 2020), a key substrate for HA production, and the expression of hyaluronan synthases (HASs), UDP-glucose-pyrophosphorylase (an enzyme for the biosynthesis of UDP-glucose) and UDP-glucose-dehydrogenase (an enzyme that converts UDP-glucose into UDP-glucuronic acid (Kakizaki et al 2004;Kultti et al 2009). Interestingly, UDP-GlcA is also a substrate for the synthesis of CS, as well as some other GAGs including dermatan and heparan sulphates.…”

Endogenously produced hyaluronan contributes to the regulation of peritoneal adhesion development

“…25,26 It was observed that 4-MU can also attenuate the mRNA expression of HASes. 27 The enzymatic degradation of HA is mediated by hyaluronidases (HYAL) in combination with β-glucuronidase and β-N-acetylglucosaminidase. The most important is the action of HYAL1 and HYAL2.…”

“…On the other hand, the metabolism of cells changes after the inhibition of HA synthesis by, for example, 4‐methylumbelliferone (4‐MU), which depletes the cytosolic pool of UDP‐GlcUA 25,26 . It was observed that 4‐MU can also attenuate the mRNA expression of HASes 27 …”

Inhibitor of Hyaluronic Acid Synthesis 4-Methylumbelliferone as an Anti-Inflammatory Modulator of LPS-Mediated Astrocyte Responses

“…4-MU is available as a spasmolytic, over-the-counter drug in several European countries (named "hymecromone"). It was shown that 4-MU is a specific inhibitor of the HA synthesis in multiple cell lines, including fibroblasts from various primary tissues [24][25][26][27], keratinocytes [28], melanoma and pancreatic cancer cells [29,30]. Moreover, the effect of 4-MU has been shown in certain in vivo experiments.…”