The long-term objectives of this proposal are to elucidate the effects of mechanical stimuli to tissue degradation of rheumatoid arthritis and to develop a physical treatment for relieving pain and stiffness of arthritic joints. Using two human synovial cell cultures isolated from rheumatoid arthritis patients, we have recently found that mechanical shearing at a few dyn/cm 2 transiently decreases the transcriptional levels of matrix metalloproteinase (MMP)-1, MMP-13 genes as well as ets-1 transcription factor, while the same shearing increases the mRNA levels of tissue inhibitor of metalloproteinase (TIMP)-1, TIMP-2 and c-fos. These preliminary gene expression results suggest a potential use of mechanical shear stress as a therapeutic tool and allow us to test the following hypothesis: An appropriate non-stationary temporal profile of gentle mechanical shear stress at a few dyn/cm2 can maintain simultaneously a reduced mRNA level of MMP-1, 3, and -13 as well as an increased mRNA level of TIMP-1 and 2 through the down-regulation of ets-1 transcription factor. Two specific aims of this project are (i) to evaluate the proposed five non-stationary shear stress profiles for decreasing MMP rRNAs and increasing TIMP mRNAs, and (ii) to identify the function of ets-1 on mechanical stress-induced response in the simultaneous regulation of MMPs and TIMPs. We will isolate RNA from the stress-treated synovial cell cultures and determine the cDNAs levels of the specific MMPs and TIMPs as well as AP-1 and ets gene family members using a reverse transcription-polymerase chain reaction procedure. We will also measure the level of MMP proteins by immunoblotting and determine MMP activities by using zymography and a fibril degradation assay. By transfecting ets-1, we will test the function of ets-1 under mechanical stimuli. The proposed project will contribute to answer whether a non-invasive physical treatment can be developed for preventing from tissue degradation in arthritis joints.