The microbiota influence metabolic and immune homeostasis, and microbial triggers have been postulated in RA, but little is known about the oral and gut microbiomes of RA patients.
Dr. Xuan Zhang, from Peking Union Medical College, Beijing, China, and colleagues compared the gut microbiomes of 77 treatment-naïve RA patients and 80 unrelated healthy controls, 17 treatment-naive RA patients paired with 17 healthy relatives, and 21 samples from DMARD-treated RA patients. They compared oral microbiomes from treatment-naive RA patients (54 oral, 51 saliva) and healthy controls (51 dental, 47 saliva).
The oral and gut microbiomes of individuals with RA were distinct from those of healthy individuals, according to the July 27 Nature Medicine online report.
Hemophilus species were depleted in individuals with RA in all microbiomes and negatively correlated with the levels of serum autoantibodies, whereas Lactobacillus salivarius was over-represented in RA patients at all three sites and was especially elevated in patients with very active RA.
A microbiome-based model that included eight of the gut metagenomic linkage groups (MLGs) identified RA patients with 83.8% sensitivity and 92.2% specificity. Another model that used dental MLGs and two salivary MLGs yielded 80% sensitivity and 86% specificity for identifying RA patients.
DMARD treatment partially restored the RA microbiome in the direction of healthy controls, and MLG-based models accurately predicted the response to DMARD treatment.
“Our comprehensive survey of the gut and oral microbiomes in individuals with RA supports the notion that RA represents a state of chronic inflammation that might be provoked or aggravated by the overgrowth of pathogenic bacteria or a lack of immune-modulating commensal bacteria,” the researchers concluded. “These findings are a first step toward microbiome-based therapeutics and patient stratification in preclinical and clinical phases of RA.”
“With further investigation of the possible mechanisms, microbiome-assisted diagnosis, prognosis and treatment could hold great promise for effective long-term management of autoimmune diseases such as RA, together with their accompanying dental and cardiovascular symptoms,” they added.
Dr. Zhang and coauthors Dr. Yingrui Li and Dr. Jun Wang did not respond to a request for comments.
The authors reported no disclosures.