The role of Fibronectin in the pathogenesis of antigen‐induced arthritis in the rabbit

Abstract

Fibronectin (FN), a high molecular weight glycoprotein, is present in plasma and is a normal structural component of the synovium in the rabbit, as it is in man. FN is also involved in the sequence of changes seen in synovium in experimental antigen-induced arthritis. Its widespread distribution in inflamed synovia in the initial acute phase of induced arthritis probably merely reflects the presence of FN of plasma origin in serous exudates. In established experimental arthritis, FN co-distributes with fibrin, while in synovia undergoing organisation, FN is present intracellularly in several types of mesenchymal cells (suggesting local synthesis) and is deposited on immature collagen fibrils. However, it is no longer present when mature collagen is formed. The persistence of FN, along with fibrin, in inflamed joints, and its involvement in fibrosis, suggest that it may play a significant part in determining the chronicity of this form of experimental arthritis.

A fibrin based model for rheumatoid synovitis

“…The ability of fibronectin to cross link fibrin matrices, found both in wounds and in the inflamed joint, may be relevant for the induction of fibroblast invasiveness. [20][21][22] Fibronectin provides binding sites for cell attachment, and dynamic interactions between integrins and their matrix ligands allow fibroblast locomotion through the network. 23 Interestingly, in RA, fibrin-fibronectin complexes have been associated with pannus formation and with an erosive tendency.…”

Pathogenesis of chronic inflammation in experimental ferritin‐induced arthritis. V. Electron microscopic localization of specific antibodies in the synovial membrane

“…Samples for histopathology (fixed by immersion in 10% formaldehyde) were taken parallel to those obtained for electron microscopy. The electron microscopy specimen tissues were then washed in successively increasing concentrations of sucrose ( 5 , 10,15,20, and 25% plus 5% glycerin), 1 h each, and snap-frozen in a solid C0,-isopentane mixture to maximize cell preservation. The frozen tissues were stored at -20°C until processed.…”