An analysis of stool samples from arthritis patients and healthy individuals has revealed changes in the gut microbiome that are associated with inflammatory disease.
Writing in the journal Science Translational Medicine, researchers described the investigation of 440 stool shotgun metagenomes. Almost exactly half, 221, of the samples came from patients with rheumatoid arthritis, ankylosing spondylitis, or psoriatic arthritis. The other 219 samples were taken from people who were healthy or had joint pain that lacked an underlying inflammatory cause.
The analysis revealed changes to the microbiome that were shared across people with the inflammatory arthritis conditions. Oral, proinflammatory, and mucin-degrading microbes were enriched in patients with the conditions at the expense of some organisms typically found in the human gut.
Further work identified microbiome-driven functional pathways associated with the diseases. Changes in vitamin B salvage and biosynthesis and enrichment of iron sequestration were among the several differentially encoded pathways in the gut microbiome of patients with inflammatory arthritis.
One outstanding question is whether the pathways are driving the disease or reflecting the conditions. The researchers said several of the changes seen in patients with inflammation could have causal roles, but they hypothesized that the microbiome pathways “are mainly positive feedback responses to changes in host physiology and immune homeostasis.”
Further research is needed to determine if the functional changes caused the inflammatory conditions, arise in response to the diseases, or both. If a causal relationship is identified, pathways and molecules named in the paper could have therapeutic importance.
