FRI0084 The tonsil microbiome is involved in rheumatoid arthritis
Authors: J Li, J He, K Deng, J Qin, Y Jin, J Chen, Z Li
Journal: Annals of the Rheumatic Diseases (2017)

<h3>Background</h3> Rheumatoid arthritis (RA) is a prevalent systemic autoimmune disease characterized by the production of autoantibodies<sup>1</sup>. The tonsil has been demonstrated to be a site of citrullination, and tonsillectomy has been reported to be a potential treatment of RA, suggesting the possibility that the tonsil could be a site of autoimmunity generation in RA<sup>2,3</sup>. The dysbiosis of gut microbiome and the associated host immune response has been implicated in the initiation and progression of RA<sup>4–6</sup>. However, there is no in-depth studies on the role of tonsil microbiota in RA. Thus, studies of the characteristics of tonsil microbiome in RA patients, the underlying mechanisms, as well as specific markers for the diagnosis and therapeutic evaluation for RA, are critical for the early diagnosis and prevention of RA. <h3>Objectives</h3> Therefore, we aimed to define the association of RA with tonsil microbiome as well as a microbial and metabolite profile that could predict disease status. <h3>Methods</h3> 16S rRNA gene sequencing was utilized on 220 tonsil swab samples (121 RA patients and 99 healthy controls) as well as 78 fecal samples (68 RA and 10 controls). Analysis of microbial taxa and metabolic pathway were performed to characterise and compare the tonsil microbiome of RA patients and healthy subjects <h3>Results</h3> Results showed that the tonsil harbored a unique microbiome relative to that present in the fecal samples. Patients with RA exhibited different tonsil microbiome from controls. A taxon-level analysis suggested that the relative abundance of 26 microbial clades were significantly altered, with 7 taxa increased and 19 taxa decreased in RA samples. Noticeably, we observed an expansion of rare microbial lineages as well as an alteration in microbial cladogenesis within RA patients. RA tonsil microbiota was associated with smoke, anti-peripheral factor, rheumatoid factors, disease duration and activity. Furthermore, we identified that 86 genes associated with bacterial metabolic pathway were enriched in RA tonsil microbiome. <h3>Conclusions</h3> Our results demonstrated that the RA tonsil microbiome differs from that of healthy controls, which correlates with systemic autoimmune changes and may potentially drives initiation of RA. <h3>References</h3> McInnes IB, and Schett G. The pathogenesis of rheumatoid arthritis. N Engl J Med. 2011, 365(23): 2205–2219. Kawano M, Okada K, Muramoto H, et al. Simultaneous, clonally identical T cellexpansion in tonsil and synovium in a patient with rheumatoid arthritis and chronic tonsillitis. Arthritis Rheum. 2003, 48(9): 2483–2488. Makrygiannakis D, af Klint E, Lundberg IE, et al. Citrullination is an inflammation-dependent process. Ann Rheum Dis. 2006, 65(9): 1219–1222. Scher JU and Abramson SB. The microbiome and rheumatoid arthritis. Nat Rev Rheumatol, 2011, 7(10): 569–578. Scher JU, Sczesnak A, Longman RS, et al. Expansion of intestinal Prevotella copri correlates with enhanced susceptibility to arthritis. Elife, 2013, 2:e01202. Zhang X, Zhang D, Jia H, et al. The oral and gut microbiomes are perturbed in rheumatoid arthritis and partly normalized after treatment. Nat Med, 2015, 21(8): 895–905. <h3>Disclosure of Interest</h3> None declared