Oral bacterial DNAs in synovial fluids of arthritis patients

Abstract

Arthritis may be triggered by microbial constituents, more specifically, bacterial cell wall fragments, or bacterial DNA. The aim of this study was to analyze the amount of oral bacterial DNA in synovial fluids (SF) of arthritis patients. SF from 15 rheumatoid arthritis (RA) patients, 15 arthritides (non-RA) patients and 9 osteoarthritis (control) patients were extracted for oral bacterial DNA. DNA was used in a checkerboard DNA/DNA hybridization set-up, in order to identify 40 different species. The mean number+-standard deviation (SD) of bacterial species in SF was 22.7 (5.6) in the RA group and 13.1 (3.9) in the control group (p=0.001). The mean number of species found in non-RA SF was 19.7 (7.8), (p=0.033). The qualitative differences in species between the groups were most notable for Actinobacillus actinomycetemcomitans, Eubacterium saburreum, Streptococcus anginosus, Actinomyces israelii, Streptococcus intermedius, Tannerella forsythensis, Prevotella melaninogenica and Prevotella intermedia . DNAs from these species were exclusively detected in RA SF and in non-RA SF. In RA SF, 33% of the species were found in high (>10 6 cells per 100 ml) concentrations compared with 13.4% in the control group (p=0.001). In non-RA SF, 38.3% of the species were found in high concentrations (p<0.0001). Oral bacterial DNA is a common finding in SF of arthritis patients. These data provide evidence of differences in concentration and assortment of oral bacterial DNAs in SF, between different arthritides and controls, and may indicate a connection between oral infections and joint inflammation. Key words: rheumatoid arthritis, synovial fluid, bacterial DNA, oral infections