Humans and other mammals are not (and have never been) alone. From the moment we are born, millions of microorganisms populate our bodies and coexist with us rather peacefully for the rest of our lives. This massive anitgenic load derived from microorganisms (and their genomes) define the human microbiome. Micro-organisms living in or on us have evolved to extract the energy they require to survive, and in exchange they support the physiological, nutritional, metabolic and immune functions that have contributed to our evolutionary success. Although currently categorized as autoimmune disorders and regarded as complex genetic disease, the ultimate cause of rheumatoid arthritis (RA), psoriatic arthirits (PsA), and related conditions remain elusive. It seems that interplay between predisposing genetic factors and environmental triggers is required for disease manifestations. New insights from DNA sequence- based analyses of gut and skin microbial communities and a renewed interest in mucosal immunology suggest that the microbiome represents an important environmental factor that can modulate inflammation and autoimmune disease manifestations. Multiple animal models and novel human studies suggest a possible role for a disruption in the microbiome composition (dysbiosis) in the pathogenesis of inflammatory arthritis, presumably through activation of proinflammatory T-cells via antigenic molecules and/or bacterial-derived metabolites.
Disclosure of Interest None declared