Differential stimulation of three forms of hyaluronan synthase by TGF-β, IL-1β, and TNF-α

This study compares the regulation of three isoforms of hyaluronan synthase (HAS1 HAS2, and HAS3) transcripts and hyaluronan (HA) production by cytokines in human synovial fibroblastic cells derived from tissue from patients with rheumatoid arthritis (RA) and osteoarthritis (OA). Levels of HAS mRNA of the cells with or without stimulation were detected using a real-time fluorescence polymerase chain reaction detection system. Concentrations of HA in the culture supernatants of the cells were measured by a sandwich binding protein assay. Molecular weight of HA was evaluated by agarose gel electorophoresis. The relative proportions of the expression pattern of HAS isoforms was similar between RA and OA tissue-derived cells. HAS1 mRNA was upregulated by transforming growth factor-beta and HAS3 mRNA was upregulated by interleukin-1beta and somewhat by tumor necrosis factor-alpha in the RA cells. HAS2 remained unchanged. Differences in the expression pattern of HAS1 HAS2, and HAS3 mRNA by cytokines suggest that these three isoforms are independently and differentially regulated, and each isoform of HAS may have a different role in arthritic joint disease.