RESUMO
OBJECTIVE: Ultrasound has been therapeutically applied for pain control in rheumatoid arthritis although little physiologic effects of sonication on rheumatoid tissue were known. This investigation was conducted to determine the effects of sonication on the cell proliferation and matrix metalloproteinase (MMP) production of cultured fibroblast like synoviocytes (FLS) derived from synovial tissues of rheumatoid arthritis. METHOD: Pulsed ultrasound (1.0 MHZ, 20 msec on, 80 msec off) with varying intensities (0, 0.1, 0.25, 0.5, 0.75, 1.0 W/cm2) was applied to experimental cell groups growing as monolayers in culture plates for varying durations (0, 30, 90, 180 seconds) in the presence and absence of interleukin-1beta (IL-1beta). RESULTS: There were no significant differences in thymidine incorporation between 0, 30, 90 and 180 second sonication groups with 0.5 W/cm2 after 1 day and 2 days. There were no significant differences in thymidine incorporation between 0, 0.1, 0.25, 0.5, 0.75, 1.0 W/cm2 sonication groups 1 day and 2 days after 90 second sonication. There were significant increase in MMP-1 (p=0.025) and MMP-3 production (p=0.000) of FLS after sonication in the absence of IL-1beta but there were no significant differences in MMP-1 and MMP-3 production in the presence of IL-1beta. And MMP-1 and MMP-3 production were increased significantly in the presence of IL-1beta but not than in the absence of IL-1beta. CONCLUSION: While comparisons made between a limited number of FLS cell lines must be open to question, the overall consistency of the findings suggest sonication with nonthermal effect is not the contraindication in rheumatoid arthritis treatment but further study is needed in vivo in animal and in clinical studies.