Spondyloarthritis and the Microbiome: An Early 2021 Update

As many of you seem particularly interested in research into the gut connection to spondyloarthritis, including Ankylosing spondylitis (AS), I have been keeping an eye out for anything interesting.  A few weeks ago I spotted a new study looking at microbiome differences in patients with inflammatory bowel disease (IBD) and AS, as the prevailing belief is that these two share similar origins.[i] (This is not a new:  I noted it in my first blog post on this subject back in 2018: “…almost 70% of patients with AS have subclinical gut inflammation which indicates that the two diseases may be similar entities with a common origin.”  This paper states that previous research has found that up to 60% of people with AS have inflammation in their guts.

Previous studies have also shown a decrease in the diversity of bacterial species in those with IBD; this has also been found in those with AS, and what they do have, is predominantly inflammatory pathogens.  Whether or not this gut dysbiosis is a cause of systemic inflammation, or the result of systemic inflammation, has yet to be determined.  To further research into this topic, these scientists wanted to better characterize the gut dysbiosis in patients with IBD and/or AS.  (In January 2020, I wrote about a similar study on 150 people with AS which also found significant dysbiosis in the AS population.)

This study involved 124 patients:  20 had Crohn’s disease, 27 had ulcerative colitis, 28 had AS, 17 had both IBD and AS – and 32 controls.  They collected stool samples from all and compared the bacterial microbiomes.  The results:  all those with pathologies (i.e. AS and/or IBD) had less bacteria in general compared to controls, as has been found in previous studies. The lowest microbiota levels was found in those with Crohn’s disease, followed by those with IBD and AS.  Interestingly, the least dysbiotic group was the one with only AS.  Those with pathologies had a  higher percentage of Bacteroides and E. coli, and a decreased percentage of other bacteria, including various Clostridium species.  In patients with the axial form of AS, Bifidobacterium was significantly increased when compared to the peripheral form of the disease.

What then are main take-aways?  Firstly, definitely a lot more work needs to be done in this field, considering that 3x as many people suffer from spondyloarthropathies than do Parkinson’s disease, for example – and way more than suffer from multiple sclerosis and ALS.  Yet strangely, far more research has been conducted in all those illnesses, perhaps because they are more life-threatening.  Still, considering that spondyloarthropathies cause lifelong pain and disfigurement, with advanced cases causing people to be horrifically hunched when their spinal discs fuse, maybe it’s time more work is done.  (Bear in mind that as little work has been done on the bacterial dysbiosis of those with AS, even less has been done looking at the other “-omes” of our inner ecosystem.  In 2019, I wrote about fungal dysbiosis in spondyloarthritis but that’s the only such paper I’ve seen so far. )  The studies that do exist universally suggest lower levels of bacterial diversity and distinct dysbiosis.

Secondly,  there is “…a close relationship between disease activity and the degree of intestinal dysbiosis.”  The paper states, “An increase in AS activity corroborated with a decrease in functionality can be associated with an increase in pro-inflammatory bacteria.”  So while dysbiosis may be less significant in those with AS than in those with IBD, it is still likely a major factor and is associated with higher rheumatic disease activity.

I will, of course, continue to monitor this topic and provide you with any updates.

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[i] Cardoneanu A, Mihai C, Rezus E, Burlui A, Popa I, Cijevschi Prelipcean C. Gut microbiota changes in inflammatory bowel diseases and ankylosing spondilytis. J Gastrointestin Liver Dis. 2021 Feb 4. doi: 10.15403/jgld-2823. Epub ahead of print. PMID: 33548121.