EXPRESSION OF ENDOGENOUS RETROVIRUSES, ERV3 AND LAMBDA-4-1, IN SYNOVIAL TISSUES FROM PATIENTS WITH RHEUMATOID-ARTHRITIS

We addressed the question of whether or not expression of human endoge nous retroviruses (ERV), ERV3 and lambda 4-1, is related to the pathog enesis of rheumatoid arthritis (RA). In genomic Southern hybridization , there were no significant differences between RA patients and health y volunteers with regard to frequencies of restriction fragment length polymorphism (RFLP) patterns, for either ERV3 or lambda 4-1. By North ern blot analysis using fresh synovial tissues, cultured synovial cell s, and peripheral blood mononuclear cells (PBMC) from patients with RA , we noted two molecular species of ERV3 mRNAs of 3.5 kb and 9.0 kb si zes, and one single molecular species of lambda 4-1 mRNAs of 4.2 kb si ze. The expression was detected not only in RA patients but also in sy novial cells from osteoarthritis (OA) as a non-RA control and PBMC fro m healthy volunteers, and was not related to RA activities or treatmen ts. Although ERV3 and lambda 4-1 expression may not be directly associ ated with the pathogenic pathway of RA, the possibility exists that hu man ERV may have a causative role in autoimmune diseases, including RA . We also examined the effect of cytokines on the transcriptional regu lation of ERV3. Although the level of ERV3 expression in cultured syno vial cells did not change with IL-1 beta treatment, the level for cult ured proximal tubular epithelial cells (hKEC) was up-regulated.