Impact of NSAIDS on murine antigen induced arthritis. II. A light microscopic investigation of antiinflammatory and bone protective effects.

The impact of daily, orally administered nonsteroidal antiinflammatory drugs (NSAID) or a steroid on arthritic knee joints of mice with 1-3 weeks of antigen induced arthritis (AIA) was examined by light microscopy. Prophylactic drug effects on inflammatory cell infiltrate in synovium and joint cavity were evident only in mice treated with prednisolone (0.2-5.0 mg/kg). Treatment with diclofenac, piroxicam (both 0.5-7.5 mg/kg) or tiaprofenic acid (3-30 mg/kg) did not change these phlogistic features significantly. Striking, however, was the protective effect of piroxicam on bone apposition, a common trait in murine AIA. Among the other drugs, minor antiosteophyte effects were exerted only by prednisolone. Histological assessment was also performed on osteocyte death which was almost exclusively confined to menisci and tibial subchondral bone. Because of variability in occurrence and intensity, no clear picture emerged from drug effects on this lethal feature. Combined data from this and a previous pharmacological study, directed at chondroprotective effects, points to prednisolone as the best antiinflammatory and joint protective drug.