The Role of the Gut Microbiome in Ankylosing Spondylitis

By Spondylitis Association of America

Thursday, January 23, 2020

To better understand the role of the gut microbiome [1] in ankylosing spondylitis (AS), researchers conducted a case-control study [2] on a total of 250 Chinese participants (127 of whom had AS, and 123 who did not.) Participants were divided and grouped into two cohorts: the “discovery cohort” included 97 people with AS and 93 without AS; the “validation cohort” included 30 people with AS and 30 without AS. Stool samples were collected and analyzed from all. The goals of the study were (1) to assess and determine key gut microbial characteristics driving disease, and (2) to examine the effects of TNF inhibitor therapy on the gut microbiome of AS patients.

Key Findings:

  1. The gut microbiome in patients with ankylosing spondylitis was found to be “shaped” to carry a higher load of certain peptides[3] that are indicated by the HLA-B27 gene.
  2. TNF inhibitor therapy was found to be effective in repairing the agitated microbiome found in untreated AS patients.
  3. The gut microbiome was substantially different between patients with AS who were on TNF inhibitors, and AS patients that were not on TNF inhibitors. The microbiome in those AS patients who were on TNF inhibitors was not much different from those who did not have AS.
  4. Seven species of microbial bacteria were identified as being markedly different in their quantities / concentrations in those with AS when compared to healthy controls.
  5. In the AS group there was a higher presence of Clostridiales bacterium 1 7 47FAA, Clostridium bolteae, and Clostridium hatheway, and depletion of Bifidobacterium adolescentis, Coprococcus comes, Lachnospiraceae bacterium 5 1 63FAA, and Roseburia inulinivorans.

Researchers concluded that, “These findings are consistent with disease models in which AS pathogenesis is driven by interactions between a genetically primed host immune system, and the gut microbiome and point to potential therapeutic and/or preventative approaches for the disease.”

The study serves to reconfirm the key role of the gut microbiome in the development of AS, as well as provide additional clues to new treatments and possible prevention. The impact of TNF inhibitor medications in altering and repairing the gut microbiome in AS patients is also emphasized. Study limitations include a small sample size, and the limitation of the sample to one geographic area (as the human microbiome is found to differ greatly from region to region.)

[1] Gut Microbiome: defined as all the microorganisms, bacteria, viruses, protozoa, and fungi, and their collective genetic material present in the gastrointestinal tract.

[2] Case-Control Study: is a type of observational study in which two groups are identified and compared; one group will have a disease/outcome (in this case, AS) and one will not.

[3] Peptide: is a cell component that carries out key functions. Some peptides are involved in regulating the activities of other molecules.

For further reading see:

Treasures Come From Unexpected Sources: Lessons for Ankylosing Spondylitis?

Does the Microbiome Cause Ankylosing Spondylitis?


Yin J, Sternes PR, Wang M, et al. Shotgun metagenomics reveals an enrichment of potentially cross-reactive bacterial epitopes in ankylosing spondylitis patients, as well as the effects of TNFi therapy upon microbiome composition. Ann Rheum Dis. 2020;79(1):132-140.

Writer, R. A. C. (2020, January 7). Metagenomic Sequencing Reconfirms Key Role of Gut Microbiome in AS Pathogenesis. Retrieved January 14, 2020, from


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