Regulation of HAS expression in human synovial lining cells of TMJ by IL-1β

Hyaluronan (HA), a major glycosaminoglycan of synovial fluid, is synthesised by a class of membrane-bound HA synthase (HAS) proteins. In the present study, we investigated the regulatory roles of IL-1β on HAS gene expression and HA production by the fibroblastic synovial lining cells. The synovial lining cells from synovial membrane in human temporomandibular joint (TMJ) were cultured and characterised using immunocytochemistry with CD14, CD44, and vimentin monoclonal antibodies. With or without treatment with IL-1β, the production of HA was detected with radiometric assay and the expression of HAS mRNAs were analysed with a semi-quantitative reverse transcribed polymerase chain reaction (RT-PCR). HA synthesis was significantly augmented with 1 ng/ml of IL-1β for both 24 and 48 h stimulation, however the production of HA declined if stimulated with 10 ng/ml of IL-1β. The expression of HAS2 and 3 mRNA were enhanced about 4.2- and 7.2-fold after 4 h stimulation with 1 ng/ml of IL-1β, respectively. From these results, it is concluded that IL-1β functions on regulating HAS expression and consequently promoting the secretion of HA in synovial lining cells from TMJ.