Alterations in gut microbiota associated with lymphocyte subsets, cytokines, and disease activity in ankylosing spondylitis

Abstract Background: This study investigated gut microbiota characteristics and their associations with lymphocyte subsets, cytokines, and disease activity in patients with ankylosing spondylitis (AS). Fecal DNA from 62 AS patients and 62 healthy controls (HCs) was subjected to 16S rRNA gene sequencing. The absolute numbers of peripheral lymphocyte subsets were detected by flow cytometry, while the serum levels of cytokines were tested by cytokine bead arrays. Results: The gut microbiota diversity was significantly decreased in AS patients, compared to HCs. Proteobacteria and Patescibacteria were more abundant in AS patients than in HCs; Firmicutes, Fusobacteriota, Verrucomicrobiota, Synergistota, and Campilobacterota were less abundant in AS patients than in HCs. At the genus level, the abundances of Escherichia–Shigella were increased in AS patients compared to HCs; in contrast, the abundances of Faecalibacterium, Prevotella, Agathobacter, Roseburia, and Dialister were decreased in AS patients. The linear discriminant analysis effect size indicated that Enterobacterales was the most significant order in AS patients. The relative abundances of Agathobacter, Ruminococcus, Prevotella, and CAG–352 were correlated with lymphocyte subsets and cytokine levels; the relative abundances of Faecalibacterium, Klebsiella, and Roseburia were correlated with disease activity. In addition, specific gut microbiota were significantly correlated with peripheral blood cell count, age, and body mass index. Conclusions: The gut microbiota in AS patients differed from the gut microbiota in HCs; changes in bacterial communities were associated with the immune profile that contributes to AS pathogenesis.