The proliferation of chondrocytes and pannus in adjuvant arthritis

Inflammation and collagenase production in rats with adjuvant arthritis reduced with 13-cis-retinoic acid

Oral administration of 13-cis-retinoic acid (40 or 160 milligrams per kilogram of body weight daily) significantly reduced the inflammation associated with developing and established adjuvant arthritis, an experimentally induced arthritis in rats that resembles human rheumatoid arthritis. The amount of collagenase secreted in tissue culture by adherent cells isolated from the inflamed joints of adjuvant rats treated with 13-cis-retinoic acid also decreased as compared to the amount secreted by cells from vehicle-treated adjuvant rats. Collagenase is important in the joint destruction accompanying rheumatoid arthritis. The successful use of retinoids in the treatment of this proliferative but nonmalignant disorder demonstrates a new application of these compounds.

Role of polymorphs in inflammatory cartilage destruction in adjuvant arthritis of rats

The inflammatory destruction of cartilage in rat adjuvant arthritis has been studied by histochemistry and autoradiography. Naphthol-AS-D-chloroacetate esterase has been used as a marker for polymorphs. The evidence presented here shows that polymorphs accumulate at the cartilage-pannus border and in areas of cartilage loss. These cells appear therefore to be of decisive importance for the destruction of cartilage. Proteoglycans were demonstrated by safranin-O staining: there is a loss of PG that is particularly prominent in zones where pannus had invaded cartilage. By means of 35S labelling of proteoglycans it was possible to show that pannus containing polymorphs can invade living cartilage.