| Budget Amount *help |
¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1995: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1994: ¥1,300,000 (Direct Cost: ¥1,300,000)
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| Research Abstract |
In the present study, we examined a panel of synovial fibroblastoid cell lines (FC) established from synovial specimens in 15 patients with rheumatoid arthrithis (RA) and 5 with osteoarthritis (OA) as controls with regard to their expression of CD44 and ability to bind hyaluronan (HA). By flow-cytometry, CD44 was identified on the cell surface of FC from RA much more than FC from OA using an anti-CD44 monoclonal antibody (mAb). In addition, HA bindingwas determined to be restricted to all RA-FC expressing high levels of CD44 using soluble fluorescein-labeled HA,and the binding to FC was significantly blocked by anti-CD44 mAbs (OS/37 and J173). Western blotting of the RA-FC revealed that they expressed varying amounts of CD44 of a low molecular weight form of 85-90 kDa and some high molecular weight forms of 100,120 and 160kDa, whereas no such higher molecules exist for OA-FC.This diversity would be attributed to alternative splicing and not to variations in the degree of glycosylation. Therefore, CD44 gene activity was studied by amplifying cDNA reverse transcribed from mRNA of RA-FC with PCR using primers followed by electrophoresis.
We found that the expression of CD44 spice variants containing exons v2, v4/5, v6 and v10 were increased in all of 4 RA-FC examined, in contrast with virtual absence from OA-FC,as determined by Southern blotting, and also FACS analysis using antibodies raised against the variant portion of CD44.
Taken together, these data suggest that growth and proliferation of RA-FC is associated with induction of CD44 to bind HA,and induction of expression of CD44 variant isoforms.Thus, the determination of modes for interfering with the inflammatory functions of CD44 is a promising area of investigation for development of new therapeutic strategies for RA.
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