Gut microbiota and intestinal permeability in rheumatoid arthritis: therapeutic implications and future directions

Interactions between the intestinal microbiota, epithelial barrier and mucosal immune system have prompted investigation of gut-directed interventions in rheumatoid arthritis (RA). This review examines whether modifying these interactions can improve clinical outcomes and assesses the strength of the available evidence in RA. In experimental arthritis, interventions that preserve epithelial integrity or alter microbial metabolism can reduce disease severity, providing a biological basis for further study. However, their relevance to human RA remains uncertain, since effects observed in animal models do not establish clinical efficacy, and changes in intestinal measurements alone do not demonstrate improvement in joint disease. Future controlled trials should assess disease activity, and physical function alongside microbial composition and function, intestinal measurements and immune responses. Repeated sampling may help establish whether intestinal changes precede or accompany clinical improvement, while recording medication exposure and dietary intake is needed to interpret these relationships. Candidate biomarkers will require prospective validation before they can be used to select patients for treatment. These studies should determine whether gut-directed interventions provide additional clinical benefit, in whom, and at what risk.