Presence of bacterial DNA and bacterial peptidoglycans in joints of patients with rheumatoid arthritis and other arthritides

Objective. The continuous presence of bacteria or their degraded antigens i n the synovium may be involved in the pathogenesis of rheumatoid arthritis (RA), The aim of this study was to determine the presence of bacterial nucl eic acids and bacterial cell wall constituents in the joints of patients wi th RA and other forms of arthritis. Methods. Joint samples were obtained from patients with RA (n = 26), septic arthritis (n = 2), inflammatory osteoarthritis (n = 5), and gout (n = 6), and joint trauma (n = 1), Universal 16S-ribosomal RNA primers were used to detect the presence of bacterial DNA in these samples, using stringent regi mens for sample collection and molecular microbiologic analysis. Automated sequencing and comparative data analysis were performed to identify the spe cies, The presence of bacterial peptidoglycan-polysaccharide complexes in s ynovial tissue was detected by immunohistologic analysis with a specific an tibody. Results. The bacterial species cultured from the synovium could be identifi ed in both of the patients with septic arthritis, DNA amplicons were also d etected in the synovial fluid and/or tissue samples from 5 patients with RA and 2 patients with crystal-induced arthritis; these originated from multi ple bacterial species. Staining for peptidoglycan-polysaccharide complexes was positive in the synovial tissue of both patients with septic arthritis, 16 with RA, 4 with inflammatory osteoarthritis, 4 with crystal-induced art hropathy, and 1 with joint trauma, The staining was mainly found in cells i n the synovial sublining, including macrophages. Conclusion. The results indicate that bacterial DNA and bacterial cell wall constituents are retained in the joints of some patients with arthritis, w here they might enhance synovial inflammation.