The available data indicate that seropositive rheumatoid arthritis (RA) develops as a result of systemic, autoimmune reaction directed against a range of "self" peptides/proteins that have undergone specific forms of post-translational modification. The development and progress of autoimmunity may be triggered by non-specific, local inflammatory processes outside the joints, for example in the oral or respiratory mucous membrane. The disease occurs in genetically susceptible individuals under the influence of environmental risk factors that promote autoimmunity and consequently the inflammatory process. Smoking is particularly linked with RA pathogenesis. Synovitis of multiple, symmetrical, peripheral joints is the most typical feature of RA which results in irreversible damage to joints structure and as a consequence in disability of patients. However, the inflammatory process in the course of RA has a systemic, constitutional nature. Therefore, extra-articular symptoms with internal organ involvement may occur additionally to synovitis, what is an unfavorable prognostic factor. Extra-articular manifestations of RA are associated with the high disease activity both inflammatory and immunological. They occur in patients with severe form of the disease and contribute to a significant lifespan reduction. This is usually associated with progressive atherosclerosis and cardiovascular complications. The systemic inhibition of an abnormal immune system activity is the mainstay of the effective RA treatment. The currently used disease modifying antirheumatic drugs affect the activity and function of different constituents of the immune system, including B and T lymphocytes and the main pro-inflammatory cytokines, and contribute to autoimmune and inflammatory processes.
Keywords: autoimmunity; extraarticular symptoms; inflammation; rheumatoid arthritis; systemic disease.