Characterization of Fecal Microbiota in Ankylosing Spondylitis: Pathogenesis Insights and Therapeutic Opportunities - A Systematic Review
Bibliographic record
Abstract
Objectives Recent evidence suggests that the gut microbiota may play a crucial role in the pathogenesis of ankylosing spondylitis (AS). This systematic review aims to examine the existing literature to explore changes in gut microbiota composition between AS patients and healthy controls (HC) to identify microbial signatures associated with AS. Understanding these alterations could enhance our knowledge of the mechanisms underlying AS. Methods We queried PubMed, Web of Science, Scopus, Embase, and Cochrane databases through May 2024 to identify studies comparing stool microbiota composition in AS patients and healthy controls (HC). Following PRISMA guidelines, our search yielded 1,163 studies. We included studies comparing microbiota in AS patients and HC. We excluded duplicates, animal studies, case reports, conference abstracts, non-English articles, irrelevant studies, non-full-text manuscripts, and Mendelian randomization studies, as these do not provide direct observational data on microbiota composition and could introduce methodological heterogeneity. Results After screening 184 studies, 18 manuscripts were included: 14 prospective cohort studies, 2 case-control studies, and 2 cross-sectional studies (Figure 1). These studies covered a total of 900 ankylosing spondylitis (AS) patients and 734 healthy controls (HC). The majority of the participants were male, with 73.8% in the AS group and 66.7% in the HC group, and most participants (73.4%) were of Asian descent. HLA-B27 status was reported in 13 studies, with a 92.3% positive rate among the AS patients. Notably, none of the AS or HC participants, except for 1 study, had received antibiotics in the 3 months prior to enrollment. At the phylum level, 12 studies (66.6%) reported significant changes in microbiota composition (Figure 2). Actinobacteria, Firmicutes, and Proteobacteria were increased in 8, 6, and 5 studies, respectively, while Bacteroidetes, Fusobacteria, and Verrucomicrobia were decreased in 5, 3, and 3 studies, respectively. At the genus level, 16 studies (88.8%) observed changes. Prevotella, Escherichia-Shigella, Streptococcus, and Collinsella were increased in 6, 6, 5, and 4 studies, respectively, while Bacteroides, Lachnospira, and Dialister were decreased in 9, 4, and 4 studies, respectively. Prevotella and Collinsella have been linked to inflammatory diseases in previous studies, suggesting their potential involvement in the inflammatory processes observed in AS patients. On the other hand, a reduction in Lachnospira has been associated with increased inflammation, indicating its potential protective role in inflammatory conditions. Figure 1: Alterations in Microbiota Composition at the Phylum Level in AS Patients Compared to Healthy Controls Figure 2: Alterations in Microbiota Composition at the Genus Level in AS Patients Compared to Healthy Controls Conclusion Our findings reveal significant differences in gut microbiota composition between AS patients and healthy controls, indicating a role of microbiota in AS pathogenesis. These findings highlight the potential for microbiota-targeted therapies in AS treatment.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.006 | 0.024 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.009 | 0.008 |
| Bibliometrics | 0.012 | 0.009 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.003 | 0.002 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.002 | 0.001 |
| Insufficient payload (model declined to judge) | 0.004 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".