Molecular characterisation of the synovial fluid microbiome in rheumatoid arthritis patients and healthy control subjects

• Published in: PloS one Vol. 14; no. 11; p. e0225110
• Main Authors: Hammad, Dargham Bayan Mohsen, Liyanapathirana, Veranja, Tonge, Daniel Paul
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 21.11.2019; Public Library of Science (PLoS)
• Subjects: Aged; Analysis; Arthritis; Arthritis, Rheumatoid - diagnosis; Arthritis, Rheumatoid - etiology; Arthritis, Rheumatoid - metabolism; Autoimmune diseases; Bacteria; Bacteria - classification; Bacteria - genetics; Bacterial genetics; Biology and Life Sciences; Biomarkers; Cardiovascular disease; Case-Control Studies; Cloning; Colonization; Cytokines; Cytokines - metabolism; Deoxyribonucleic acid; DNA; Dysbiosis; Enzyme-linked immunosorbent assay; Female; Fluid; Fluids; Fungi; Gene sequencing; Genes; Humans; Inflammation Mediators - metabolism; Inflammatory diseases; Interleukin 22; Interleukin 23; Interleukin 6; Life sciences; Male; Medical research; Medicine and Health Sciences; Microbiomes; Microbiota; Microorganisms; Middle Aged; Niches; Research and Analysis Methods; Rheumatoid arthritis; Rheumatoid factor; RNA; RNA, Ribosomal, 16S; rRNA 16S; Spacer region; Statistical analysis; Statistical methods; Synovial fluid; Synovial Fluid - microbiology; United Kingdom > UK; England
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0225110

The presence and identity of bacterial and fungal DNA in the synovial fluid of rheumatoid arthritis (RA) patients and healthy control subjects was investigated through amplification and sequencing of the bacterial 16S rRNA gene and fungal internal transcribed spacer region 2 respectively. Synovial fluid concentrations of the cytokines IL-6, IL-17A, IL22 and IL-23 were determined by ELISA. Bacterial 16S rRNA genes were detected in 87.5% RA patients, and all healthy control subjects. At the phylum level, the microbiome was predominated by Proteobacteria (Control = 83.5%, RA = 79.3%) and Firmicutes (Control = 16.1%, RA = 20.3%), and to a much lesser extent, Actinobacteria (Control = 0.2%, RA = 0.3%) and Bacteroidetes (Control = 0.1%, RA = 0.1%). Fungal DNA was identified in 75% RA samples, and 88.8% healthy controls. At the phylum level, synovial fluid was predominated by members of the Basidiomycota (Control = 53.9%, RA = 46.9%) and Ascomycota (Control = 35.1%, RA = 50.8%) phyla. Statistical analysis revealed key taxa that were differentially present or abundant dependent on disease status. This study reports the presence of a synovial fluid microbiome, and determines that this is modulated by disease status (RA) as are other classical microbiome niches.