Synovial remodeling process induced by type V collagen immunization in rabbits.

The pathogenesis of diffuse connective tissue diseases is still unknown despite studies of the autoimmunity aspects related to extracellular matrix elements, mainly the collagens. Articulations are frequently affected by the synovitis process in these diseases. The objective of the present study was to verify the morphologic aspects of the synovial membrane of rabbits immunized with type V collagen, which has some particular characteristics 75 days after the first antigen inoculation and when compared to control animals. The synovial membrane of the animals sacrificed after 75 days of immunization presented an intense remodeling phenomenon along the connective tissue screen and interlobular septa of the adipose-muscle tissue screen compartment. The remodeling process determined type I and III collagen fiber depositions in the vascular and connective tissue compartments of the synovial membrane. The nutrient vessels of the adipose-muscle compartment showed a similar remodeling process, which resulted in small vessel occlusion. Few residual inflammatory foci consisting of monocytes and eosinophils were observed. Thus, our experimental model reproduces morphologic changes in different tissues, characterized by an extracellular matrix remodeling process similar to those observed in many diffuse connective tissue diseases such as systemic lupus erytematosus and scleroderma. Therefore, this model could be useful in understanding the pathogenesis and the treatment of these diseases.