The following article is a part of conference coverage from the American College of Rheumatology (ACR) Convergence 2021, being held virtually from November 3 to 10, 2021. The team at Rheumatology Advisor will be reporting on the latest news and research conducted by leading experts in rheumatology. Check back for more from the ACR Convergence 2021.


Patients with axial spondyloarthritis (axSpA) and its related immune-mediated diseases share a taxonomic microbiome signature, according to study results presented at the American College of Rheumatology (ACR) Convergence 2021, held virtually from November 3 to 10, 2021.

Researchers aimed to characterize the shared gut microbiota signature for axSpA and its related diseases, and for each individual disease.

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Patients with axSpA, acute anterior uveitis (AAU), and Crohn disease (CD) were eligible for inclusion in the study. Fecal samples were collected and 16S rRNA gene sequencing used to determine microbiome composition. Confounding with respect to patient characteristics, human leukocyte antigen (HLA)-B27 expression, inflammatory markers, and the presence of other immune-mediated diseases was assessed using nested linear models and likelihood ratio tests.

Overall, 111 patients with a diagnosis of axSpA, 79 with CD, and 110 with AAU were enrolled in the current study; 63 control individuals were also included. Average age of participants was 39.1±12.3 years; 53% were men. Prevalence of HLA-B27 was 63.0% (87.4% in axSpA; 77.3% in AAU; and 8.9% in CD) among patients and 7.9% among control participants.

Among patients with axSpA and AAU, the dominant phylum was Firmicutes, followed by Bacteroidetes and Actinobacteria. Among patients with CD, Firmicutes was also dominant; however, Proteobacteria was richer than Actinobacteria. Compared with control participants, patients shared a gut microbiome signature at the genus level, which included enrichments in Veillonella and Lactobacillus, as well as a strong depletion of Blautia and other Firmicutes like Fusicatenibacter, Lachnospiraceae FCS020, and Roseburia.

When comparing separate disease phenotype, patients with CD has different genera compared with control participants, which primarily included depletions in Clostridiales (Roseburia, Coprococcus, Ruminococcaceae) and enrichments of pathogen-harboring genera such as Escherichia-Shigella and Fusobacterium. Patients with axSpA had a unique enrichment of Collinsella and depletion of Cupriavidus. Participants with HLA-B27 had an enrichment in several Firmicutes, primarily Faecalibacterium, as well as Rominococcaceae and Lachnospiraceae NK4A136. Many of these enrichments were shared among patients with AUU, including significantly increased Coprococcus.

Researchers concluded, “There is a robust shared taxonomic signature among related immune-mediated diseases, in addition to individual disease phenotype signatures.”

Disclosure: Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures. 


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Rodriguez VR, Essex M, Rademacher J, et al. Axial spondyloarthritis and its related immune-mediated diseases share a gut microbiome signature besides their own distinctive profile. Presented at: ACR Convergence 2021; November 5 to 10, 2021. Abstract 0062.