The Impact of Oral-Gut Microbiota Structure and Its Manipulation on RA Development and Management

Rheumatoid arthritis (RA) is a prevalent autoimmune disease shaped by genetic susceptibility and environmental triggers, particularly the microbiota. Numerous studies have documented substantial structural differences in the oral-gut microbiota between patients with RA and healthy individuals. Emerging evidence suggests that upregulation of specific pathobionts-including Porphyromonas gingivalis, Aggregatibacter actinomycetemcomitans, and Prevotella copri-coupled with autoantigen mimicry and inflammatory cascades, may contribute to RA initiation at extra-articular sites. Conversely, several immunoregulatory bacterial species, such as Bacteroides fragilis, Prevotella histicola, and Clostridium spp., are depleted in patients with RA. Importantly, nutritional factors (including, minerals, vitamins, fiber, flavonoids and polyphenols) and dietary patterns (e.g., Western diet, high-fat diet, Mediterranean diet, fasting, protein- or carbohydrate-rich diets) profoundly shape oral-gut microbial composition, and dietary interventions can either potentiate or suppress these microbial populations. Accordingly, recent management strategies have focused on manipulating dysbiosis through probiotic supplementation (e.g., immunomodulatory Lactobacillus strains), fecal microbiota transplantation (FMT), antibiotic administration, and targeted nutritional interventions that support probiotic efficacy and restore eubiosis. This review discusses the characteristic microbiota structure in patients with RA and evaluates emerging therapeutic strategies-FMT, antibiotics, probiotics, and nutrition-as integrated approaches for RA management.