RESUMEN
The purpose of this study is to examine effects of low-intensity pulsed ultrasound (LIPUS) on metabolism of hyaluronan (HA) in synovial membrane cells stimulated by IL-1ß. Rabbit knee synovial membrane cell line, HIG-82, was cultured in medium with the presence or absence of 1 ng/mL IL-1ß, and after 4 h the cell was exposed to LIPUS for 15 min. The mRNA levels of HA synthase (HAS) 2,3, hyaluronidase (HYAL) 2, and cyclooxygenase (COX)-2 were examined by real-time PCR analysis. Concentrations of HA and PGE2 were quantified by use of enzyme linked immunosorbent assay (ELISA). The COX-2 level was analyzed by western blotting. Gene levels of HAS2 and HAS3 in IL-1ß-stimulated cells were up-regulated significantly (p < 0.01) by LIPUS. HYAL2 mRNA was up-regulated by the treatment with IL-1ß, whereas down-regulated significantly (p < 0.01) by the following LIPUS exposure. Furthermore, IL-1ß stimulation enhanced COX-2 and PGE2 expression as compared to the untreated control, and IL-1ß-induced COX-2 and PGE2 expression was inhibited by LIPUS. These results suggest that LIPUS enhanced HA synthesis and inhibited HYAL2 expression, leading to the accumulation of high-molecular weight HA. Therefore, LIPUS stimulation may be a better candidate as medical remedy to treat inflammatory joint diseases accompanied with HA degradation in synovial fluid.