Alterations in gut microbiota may be connected to the onset of rheumatoid arthritis, potentially leading to identifiable symptoms, according to a study.
In individuals who went on to develop this autoimmune disease, researchers observed the most changes, or "instabilities," in particular strains of gut bacteria associated with inflammation occurring 10 months before diagnosis — indicating that these gut alterations might indicate a later stage.
An autoimmune disorder occurs when the immune system, which typically aids the body in combating infections and illnesses, mistakenly attacks healthy tissues and organs.
Rheumatoid arthritis is a long-term autoimmune condition characterised by inflammation, resulting in pain within the joints.
Nevertheless, it remains uncertain whether shifts, or "instabilities," in gut microorganisms initiate the disease or are a consequence of it, the investigators from the University of Leeds, UK, noted.
The results, published in the Annals of the Rheumatic Diseases, may assist in identifying individuals who are most susceptible to rheumatoid arthritis and who may need tailored treatments, according to their findings.
The research team monitored 124 individuals at risk of developing rheumatoid arthritis over 15 months; among them, seven received a new diagnosis, 22 were healthy, and the rest were considered at risk. Stool and blood samples collected five times throughout the study period facilitated the analysis of changes in gut microbiota.
The researchers found that those at risk had 'anticyclic citrullinated protein', or anti-CCP, antibodies -- known to attack healthy cells and to be specific to rheumatoid arthritis -- and experienced joint pain in the past three months.
Of the 124 participants, 30 went on to develop the condition, the researchers said.
The team found that diversity of gut microbes in these 30 had notably reduced, compared to the healthy participants. Specifically, 'alpha diversity' -- a common measure of gut health and closely related with disease status -- had reduced.
However, alpha diversity was also reduced in those who did not progress to developing rheumatoid arthritis, the researchers found.
In these participants, the autoimmune condition was related to anti-CCP antibody levels -- those having low levels of the antibodies specific to rheumatoid arthritis had a gut microbe diversity similar to that in the healthy group, the team said.
Risk factors known to contribute to rheumatoid arthritis, such as genetic and blood-related ones, were also linked with a lower diversity of gut bugs.
However, the greatest instability in gut bugs was seen in the participants who developed the chronic condition up to 10 months prior to diagnosis -- following which the gut profile remained relatively stable, the researchers said.
This suggested that changes to the gut microbes could be a late stage phenomenon, they said.
The authors said that being an observational study, direct cause-and-effect links between gut changes and developing rheumatoid arthritis could not be drawn.
"Individuals at risk of rheumatoid arthritis harbour a distinctive gut microbial composition, including but not limited to an overabundance of Prevotellaceae species. This microbial signature is consistent and correlates with traditional risk factors," the authors wrote.
"(Long-term) examination shows a dynamic microbial environment preceding rheumatoid arthritis onset. Further research into this late phase of disease development is merited, especially given the potential of the gut microbiome as a target for prevention, including in high-risk individuals with imminent arthritis," they wrote.
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