Microbiota and Arthritis: Correlations or Cause?

Alberto Bravo-Blas; Hannah Wessel; Simon Milling

Disclosures

Curr Opin Rheumatol. 2016;28(2):161-167. 

In This Article

Dysbiosis Correlates With Arthritis

The new broad approach to identifying potentially pathogenic commensal bacteria reveals that in people with arthritis, changes in the commensal microbiota occur, not only in the lower intestinal tract but also in the oral cavity.[9,10] Many of these data are summarised in Table 1.[8,9,10,11,12–15] For example, Scher et al.[11] demonstrated a correlation between altered bacterial community structure in periodontal samples from people with early rheumatoid arthritis (RA), observing increases in Prevotella and Leptotrichia species in patients independently of the status of their periodontal disease. The authors then reported that Prevotella species were also detected at higher frequency in stool samples from patients with new-onset untreated RA.[8] This increase in faecal Prevotella was accompanied by a reduction in Bacteriodes in these patients.[8] The authors also demonstrated, in an animal model, that colonisation of mice with Prevotella copri increased their sensitivity to experimentally induced colitis. However, independent studies[12,13] reported increased Lactobacillus salivarius and L. ruminis and a decrease in bacteria of the Porphyromonas–Prevotella group in patients with RA. Furthermore, although changes in microbial community structure were observed, the connection between P. copri and RA was also not detected in a study[9] of faecal, dental and salivary samples from a Chinese cohort of people with RA in which it was not possible to identify new-onset patients. This latter study reported an increase in L. salivarius, correlations between changes in oral and faecal microbiomes of people with RA, and functional metabolic changes in the microbial communities from RA patients.

The influence of the microbiota has also been examined in other inflammatory arthritides. Patients with psoriatic arthritis show decreased faecal bacterial diversity, including reductions in Coprococcus, Akkermansia, Ruminococcus and Pseudobutyrivibrio species.[14] In children with enthesitis-related arthritis, the faecal microbial profile was also altered, showing increased Bifidobacterium and increased Akkermansia muciniphila in a subset of patients, but decreased Lachnospiraceae and Faecalibacterium pausnitzii.[15] In both these reports, the changes were reported to resemble the dysbiosis seen during inflammatory bowel disease.

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