Morphometric quantitation of histopathologic changes in articular cartilage in an immunologically-induced rabbit model of rheumatoid arthritis.

An immune arthropathy was induced in New Zealand white rabbits by intradermal sensitization with complete Freund's adjuvant containing Mycobacterium butyricum followed by intra-articular administration of the bacterial antigen. Half of the animals were treated with 1 mg/kg/day of prednisolone sodium phosphate for 8 weeks by gavage beginning with the day of intra-articular challenge, while the remaining rabbits received the drug vehicle alone. By morphometric analysis (matrix/chondrocyte lacunae area ratio), we observed a significant decrease in cellularity in the arthritic articular cartilages from the vehicle control group. By contrast, there was a significant increase in cellularity in the patella, femoral and tibial cartilages of the steroid-treated animals as compared with that observed in the contralateral control joint. This study suggests that image analysis provides a reliable means for evaluation of architectural changes in the articular cartilage and allows for meaningful quantitation of the chondroprotective effects of drugs like prednisolone.