Quantitative metagenomics reveals unique gut microbiome biomarkers in ankylosing spondylitisOriginal paper
Karen Pendergrass is a microbiome researcher specializing in microbiome-targeted interventions (MBTIs). She systematically analyzes scientific literature to identify microbial patterns, develop hypotheses, and validate interventions. As the founder of the Microbiome Signatures Database, she bridges microbiome research with clinical practice. In 2012, based on her own investigative research, she became the first documented case of FMT for Celiac Disease, four years before the first published case study.
Read MoreWhat was studied?
This study used quantitative shotgun metagenomics to characterize the gut microbiome in ankylosing spondylitis, an inflammatory autoimmune disease linked to HLA-B27. It aimed to find microbial biomarkers distinguishing patients from healthy people. Deep sequencing on Illumina platforms generated a gene catalog, and reads were aligned to thousands of reference genomes. Differential genes, metagenomic species, and co-abundance gene groups were identified with Wilcoxon rank-sum tests. Support vector machine classifiers were then built from the microbial markers.
Who was studied?
The cohort was 211 Chinese individuals: 97 patients with ankylosing spondylitis and 114 healthy controls. Patients (57 men, 40 women) were aged 14 to 71 and diagnosed by modified New York criteria. Samples were split into a discovery set of 73 patients and 83 controls, plus a validation set of 24 patients and 31 controls. Controls were free of inflammatory bowel or rheumatic disease. People with recent antibiotic use or gastrointestinal disorders were excluded.
What were the most important findings?
A total of 23,709 genes differed between patients and controls, and patients showed a form of dysbiosis more prominent than in inflammatory bowel disease. Gut gene richness was reduced in patients (414,289 versus 539,071 genes, P = 6.68e-06). Actinobacteria were significantly increased (P = 1.50e-15), including Bifidobacterium, while Fusobacteria and Verrucomicrobia decreased. Prevotella melaninogenica, Prevotella copri, and Prevotella sp. C561 rose, whereas many Bacteroides species fell. Gene-based classifiers separated patients from controls with an area under the curve near 96.6 percent in validation.
What are the greatest implications of this study?
The findings show ankylosing spondylitis is associated with a distinct, reduced-richness gut microbiome, and that microbial markers can classify patients accurately. Notably, Bifidobacterium, a common probiotic, was enriched in patients. The authors propose that markers such as Prevotella species and bacterial proteasome genes may participate in disease pathogenesis, offering new diagnostic and treatment leads. A key limitation is that most patients were on medication, so drug effects on the microbiome cannot be ruled out.