Messenger-RNA expression of matrix metalloproteinases, tissue inhibitors of metalloproteinases, and transcription factors in rheumatic synovial cells under mechanical stimuli

In an effort to elucidate the role of mechanical stimuli in rheumatoid arthritis, we determined mRNA levels of matrix metalloproteinase (MMP)-1, MMP-3, MMP-13, tissue inhibitor of metalloproteinase (TIMP)-1 and TIMP-2, and three transcription factors (c-fos, ets-1, and ets-2) under two mechanical shearing conditions as well as simulated unloading. Human synovial cell cultures (MH7A and RA99-01), derived from rheumatoid arthritis patients, were grown for 1 h under mechanical stimuli and the transcript level was assayed by the reverse transcription-polymerase-chain reaction procedure. First, gentle shearing, estimated at ∼1 dyn/cm², induced a consistent decrease in mRNA level of MMP-1, MMP-3, MMP-13, and ets-1 and an increase in the transcript level of TIMP-1, TIMP-2, c-fos, and ets-2. Second, intermediate shearing, estimated at ∼6 dyn/cm², elevated the mRNA level of all MMPs, TIMPs, and the three transcription factors. Third, minimum mRNA level of c-fos, ets-1, and ets-2 was achieved under control conditions at rest, gentle shearing, and simulated unloading, respectively. These in vitro results support a stimulus-dependent transcriptional regulation of MMPs, TIMPs, and transcription factors in cell cultures, suggesting a potential role of shear stress in tissue degradation and prevention in rheumatic joints.