Role of endogenous enteric organisms in the reactivation of arthritis

Arthritogenicity of Yersinia enterocolitica O:8 in hamsters: analysis of the immune response

An animal model, hamster, was used for the study of Yersinia-induced arthritis. The development of arthritis, estimated by measuring the inflammation on hind paws after infection, was correlated with the kinetics of the immune response. Histological and immunofluorescence (IFI) studies and serum antibody measurements were performed. Two inflammatory peaks were observed: an acute one on day 11 post-infection (p.i.) and a chronic one on days 26-35 p.i. Joint cultures were positive until day 14 p.i. IFI was used to demonstrate the deposit of bacterial antigens in the joint. A persistent response of cellular extract-specific IgG antibodies was observed until day 94. Lipopolysaccharide-specific IgG was statistically significant on day 26 p.i. Antibodies against bands 66 and 54 were observed by immunoblotting. Polyclonal activation was detected during reactive arthritis. It is shown that Y. enterocolitica is arthritogenic in hamsters, immune mechanisms participating in the development of this disease.

Review article: Homing of mucosal immune cells--a possible connection between intestinal and articular inflammation

An adaptive immune system has developed to protect mucosa, mainly by performing immune exclusion with secretory antibodies (SIgA and SIgM) but also by downregulating pro-inflammatory antibody responses and delayed type hypersensitivity against harmless soluble proteins and the indigenous bacterial flora. In general, mucosal immunopathology appears to represent abrogation of such mucosal tolerance mechanisms. An important consequence is disturbance of the 'gatekeeper' function normally performed by the microvasculature through complementary sets of tightly regulated adhesion molecules on mucosal endothelium and circulating leukocytes. The B cells responsible for local polymeric immunoglobulin (Ig) production (mainly dimeric IgA) are stimulated initially in organized lymphoepithelial structures, particularly the Peyer's patches in the distal small intestine, from which they migrate as memory cells to secretory tissues all over the body. Mucous membranes are thus furnished with primed B cells in an integrated way, ensuring a variety of secretory antibody specificities at every exocrine site. There is currently great interest in exploiting this integrated or 'common' mucosal immune system for topical vaccination against pathogenic infectious agents and also to induce therapeutic peripheral tolerance to ameliorate T-cell-mediated autoimmune diseases. Moreover, homing of immune cells from the gut to the inflamed synovium may represent a modifiable link between intestinal immunity and chronic arthropathies.