Combination of intermittent hydrostatic pressure linking TGF-ß1, TNF-α on modulation of proteoglycan 4 metabolism in rat temporomandibular synovial fibroblasts.

OBJECTIVE: This study was designed to evaluate the combined effects of intermittent hydrostatic pressure (IHP) and TGF-ß1 or TNF-α on proteoglycan4 (PRG4) expression in rat temporomandibular synovial fibroblasts (SFs). STUDY DESIGN: Rat SFs were isolated and expanded in monolayer cultures and subjected to IHP in the presence of TGF-ß1 or TNF-α. Quantitative real-time RT-PCR was applied to analyze the PRG4 expression levels. Enzyme-linked immunosorbent assay was also used for the quantification of PRG4 accumulation in the culture medium while immunofluorescence staining was used to detect intracellular PRG4 protein expression. RESULTS: The combination of IHP and TGF-ß1 induced greater PRG4 expression than either stimulus alone. In contrast, TNF-α inhibited PRG4 expression, and this was partially alleviated by IHP. CONCLUSIONS: Our study demonstrates a beneficial role of IHP, which can be used successfully in combination with TGF-ß1 to enhance PRG4 production, and can partially counteract TNF-α-induced PRG4 inhibition in isolated rat SFs.