Microbiota and arthritis: cause or consequence?

The relationship between intestinal microbiota and arthritis has garnered significant attention, with emerging evidence suggesting a potential association between dysbiosis and various forms of inflammatory arthropathies. While observational studies have provided valuable insights into microbiota alterations in patients with arthritis, establishing causality remains challenging. Observational data, influenced by multiple confounders such as environmental factors, medication effects, and dietary habits, are insufficient to conclusively determine whether microbiota changes are somehow causally linked to arthritis. The heterogeneity of results across independent studies further complicates interpretation. To further support this hypothesis, interventional randomised trials are deemed necessary, yet their implementation in this area presents significant technical limitations. Experimental animal models offer insights into potential pathogenic mechanisms linking dysbiosis to arthritis, including compromised intestinal barrier function, the role of microbiota-derived metabolites and molecular mimicry. However, conflicting findings underscore the complexity of hostmicrobiota interactions and the challenges in establishing causality.Efforts to modulate the microbiota for arthritis treatment or prevention have shown promise, yet efficacy and applicability remains uncertain. Antibacterial drugs, dietary interventions, probiotics, and faecal microbiota transplantation have been explored, but their clinical utility awaits further validation. In conclusion, while the association between intestinal microbiota and arthritis is increasingly recognised, establishing causality remains elusive.