Human intestinal microbes can mediate development of
arthritis - Studies indicate that certain bacterial
nucleic acids may exist in synovial fluid (SF) and could be involved in
arthritis, although the underlying mechanism remains unclear. To characterize potential SF bacterial
nucleic acids, we used
16S rRNA gene amplicon sequencing to assess bacterial
nucleic acid communities in 15 synovial tissue (ST) and 110 SF samples from 125 patients with
rheumatoid arthritis (RA) and 16 ST and 42 SF samples from 58 patients with
osteoarthritis (OA). Our results showed an abundant diversity of bacterial
nucleic acids in these clinical samples, including presence of Porphyromonas and Bacteroides in all 183 samples. Agrobacterium, Comamonas, Kocuria, Meiothermus, and Rhodoplanes were more abundant in synovial tissues of
rheumatoid arthritis (STRA). Atopobium, Phascolarctobacterium, Rhodotorula mucilaginosa, Bacteroides uniformis, Rothia, Megasphaera, Turicibacter, Leptotrichia, Haemophilus parainfluenzae, Bacteroides fragilis, Porphyromonas, and Streptococcus were more abundant in synovial tissues of
osteoarthritis (STOA). Veillonella dispar, Haemophilus parainfluenzae, Prevotella copri and Treponema amylovorum were more abundant in synovial fluid of
rheumatoid arthritis (SFRA), while Bacteroides caccae was more abundant in the synovial fluid of
osteoarthritis (SFOA). Overall, this study confirms existence of bacterial
nucleic acids in SF and ST samples of RA and OA lesions and reveals potential correlations with degree of disease.