Rheumatoid arthritis (RA) is a debilitating immune disorder of unknown cause. Recent studies have raised the possibility that changes in the mucosal microbiome could be involved in disease onset and progression.

Zhang and colleagues conducted a case-control metagenome-wide association study (MGWAS) of the fecal, dental, and salivary microbiome in patients with RA. The microbiome at all three sites deviated from healthy controls, and correlated with clinical measures. The nature of the dysbiosis was slightly different at each of the sites, but common elements included a reduction in Haemophilus species and an over-representation of Lactobacillus salivarius. In addition, functional analysis revealed changes in transport and metabolism of iron, sulfur, zinc and arginine in individuals with RA.

After treatment with disease-modifying antirheumatic drugs (DMARDs), researchers found that the dysbiosis partially resolved, with the patients’ microbiomes beginning to look more like those of the control subjects.

Although the mechanisms behind the treatment-related changes are still unclear, these findings suggest possible ways of using microbiome analyses for RA diagnosis and prognosis.


Xuan Zhang, Dongya Zhang, Huijue Jia, et al. (2015) The oral and gut microbiomes are perturbed in rheumatoid arthritis and partly normalized after treatment. Nature Medicine 21, 895–905 doi:10.1038/nm.3914