[Intestines and joints: an entity?].
The intestinal inflammation and the inflammatory arthropathy in Crohn's disease and in spondyloarthropathy are tightly linked. Both forms of inflammation occur in clinical and subclinical forms in both diseases: 60% of patients with Crohn's disease have clinical and/or radiological signs of articular involvement--65% of patients belonging to the concept of spondyloarthropathy have endoscopic and/or histological signs of gut inflammation. The macrophages and the lymphocytes play a role either by the transport of bacterial antigens by macrophages from the gut to the synovium, either by the recirculation of activated lymphocytes attracted to the tissue by adhesion molecules. In both diseases, TNF alpha play a central role resulting in a rapid and spectacular improvement of the intestinal and articular inflammation by the administration of a monoclonal chimeric antibody directed against this cytokine (Infliximab). This clinical effect is associated or secondary to a restoration of the production of proinflammatory cytokines. According the importance of genetic factors in the etiopathogenesis of both diseases (mutation in the NOD2 gene for Crohn--HLA-B27 phenotype for spondyloarthropathy) future studies are necessary to find a common alteration explaining the link between gut and joint. This knowledge can help in the elucidation of the origin of both diseases.