A talented young researcher (Carles Ubeda) and his group (Abstract #2522) is looking at the fecal microbiome of early RA patients both prior to DMARD treatment and then after MTX is initiated. Although the sample size is small, he found that, on average, the diversity of the microbiome was less than healthy controls, and between 7 to 23 types of bacteria could predict the microbiome accurately in these patients.
What was really interesting was that the microbiome did not really change over follow-up but that baseline microbiome signatures predicted clinical response to MTX at 3 and 6 months, including the over-abundance of unclassified Coriobacteriaceae (r=-0.756; P Coprococcus-related OTU (r=-0.755; P .022). It seemed that in responders, the distribution of certain species changed more than in non-responders.
I wonder if this would occur for those who would become better irrespective of treatment (i.e. chicken or egg argument – those who improve have a different baseline microbiome or would this be different with other DMARDs?) Of course, we don't know the answer to that yet.
The next question I had was whether this would be totally different if we treated a patient with minocycline – knowing an antibiotic could change the microbiome but it could also potentially treat RA. Another good question perhaps that could be answered in animal models.
My final question was whether the intestinal mucosal microbiome would be different than the fecal samples and for that question, there is an answer- it is close enough so that feces can be a good surrogate.
This is very interesting research that may help to determine new mechanisms of RA treatment. Stool is not a load of crap but worthy of scientific study!
Dr. Janet Pope is Professor of Medicine at Western University and Division Head of Rheumatology. Dr. Pope's research interests include epidemiologic studies in scleroderma, classification criteria in systemic sclerosis, systemic lupus erythematosus and rheumatoid arthritis.View Full Bio