Etiology of rheumatoid arthritis

Note: More up to date information regarding RA pathogenesis may be found in lectures given by the author on this website. • • • • • Immune Mediated Inflammatory Disease In the last decade we have significantly increased our knowledge of the underlying pathobiology of rheumatoid arthritis. The introduction of targeted biological therapy has provided experiential rather than experimental evidence that multiple different immunological and inflammatory pathways are operative. Each year there are descriptions of new cytokines, mediators, and pathways that show additional promise in unraveling the complex pathobiological pathways. Rheumatoid arthritis is best characterized as an immune mediated inflammatory disease (IMID). Within a framework that recognizes both immunological activation and inflammatory pathways, we can begin to evaluate the multiple components of disease initiation and propagation. This framework highlights that once initiated and even after a putative trigger may be eliminated, there are feed forward pathways that result in an auto-perpetuating process. Histopathology Synovium The synovium, in normal joints, is a thin delicate lining that serves several important functions. The synovium serves as an important source of nutrients for cartilage since cartilage itself is avascular. In addition, synovial cells synthesize joint lubricants such as hyaluronic acid, as well as collagens and fibronectin that constitute the structural framework of the synovial interstit...