Oral Metagenomic Biomarkers in Rheumatoid Arthritis

Study Summary

Rheumatoid Arthritis (RA) is a chronic and potentially severe autoimmune disease affecting 2 million in the United States. The role of environmental factors in modulating autoimmunity pathogenesis has been clearly described and yet the specific mechanisms of action remain poorly understood. A growing body of evidence implicates microbiota of mucosal surfaces in the development of autoimmune disorders. Various studies have clearly linked RA to periodontal disease. The latter is linked to the red-complex that includes the oral bacterium Porphyromonas gingivalis. And yet there has not been a systematic analysis of the oral microbiota in RA to determine whether there are specific markers for P. gingivalis (and other oral bacteria) that are linked to RA. In this study, the investigators will characterize oral microbial composition (microbiome) and gene content (metagenome) of DNA isolated from oral samples obtained from patients with (i) early stage RA prior to biologics treatments and (ii) subsets of RA patients who are responsive or unresponsive to anti-TNF-alpha therapy. The innovative aspect of this study is going beyond the identification of oral bacterial species, to the level of strains and genes that are associated with these groups. The overall hypothesis is that oral microbial variation exists between individuals that influences development of autoimmunity and autoimmune disease.

Primary Outcome

A Wilcoxon rank-sum test will be computed on each profile to identify differential metagenomic gene content between each pair of groups (RA patients and controls). The potential microbial functional roles of the KEGG orthologues and eggnog orthologue groups markers in the oral microbiota of RA patients will also be assessed. All results will be corrected for multiple testing using a false discovery rate approach.

Interventions

• OTHER Saliva Collection
• PROCEDURE Dental Plaque
• OTHER Multi-dimensional health assessment questionnaire (MDHAQ)