Reverse transcriptase-PCR analysis of bacterial rRNA for detection and characterization of bacterial species in arthritis synovial tissue

Onset of rheumatoid arthritis (RA) is widely believed to be preceded by exp osure to some environmental trigger such as bacterial infectious agents. Th e influence of bacteria on RA disease onset or pathology has to date been c ontroversial, due to inconsistencies between groups in the report of bacter ial species Isolated from RA disease tissue. Using a modified technique of reverse transcriptase-PCR amplification, we have detected bacterial rRNA in the synovial tissue of late-stage RA and non-RA arthritis controls, This m ay be suggestive of the presence of live bacteria. Sequencing of cloned com plementary rDNA (crDNA) products revealed a number of bacterial sequences i n joint tissue from each patient, and from these analyses a comprehensive p rofile of the organisms present was compiled. This revealed a number of dif ferent organisms in each patient, some of which are common to both RA and n on-RA controls and are probably opportunistic colonizers of previously dise ased tissue and others which are unique species, These latter organisms may be candidates for a specific role in disease pathology and require further investigation to exclude them as causative agents in the complex bacterial millieu. In addition, many of the detected bacterial species have not been identified previously from synovial tissue or fluid from arthritis patient s. These may not be easily cultivable, since they were not revealed in prev ious studies using conventional in vitro bacterial culture methods. In situ hybridization analyses have revealed the joint-associated bacterial rRNA t o be both intra- and extracellular, The role of viable bacteria or their nu cleic acids as triggers in disease onset or pathology in either RA or non-R A arthritis controls is unclear and requires further investigation.