Degradation in vivo of articular cartilage in rheumatoid arthritis and juvenile chronic arthritis by cathepsin G and elastase from polymorphonuclear leukocytes

Summary Peroxidase-anti-peroxidase (PAP) staining and specific antibodies against cathepsin G and elastase from polymorphonuclear leukocytes (PMN) were applied to pannus-free and microscopically intact superficial articular cartilage. Restricted local deposits containing cathepsin G and elastase were found in three of ten patients with seropositive rheumatoid arthritis (RA), in one of three patients with seronegative RA and in one patient with juvenile chronic arthritis (JCA). Similarly, localized deposits of IgG and C3 were found in the patients with seropositive RA and JCA, but not in the patient with seronegative RA. Adjacent sections exhibited esterase activity in and around the PMN. In proteinase-positive areas from patients with seropositive RA the inhibitors ₁-proteinase inhibitor (₁-PI) and ₂-macroglobulin (₂-MG) were present in two of three and one of three patients, respectively. In JCA only ₁-proteinase inhibitor was present, and in seronegative RA no inhibitors were found. No staining of articular cartilage was observed in a patient with psoriatic arthritis. One of three cases with osteoarthritis exhibited patchy superficial staining for IgG only. In articular cartilage covered by pannus, in three patients with seropositive RA, in one with seronegative RA and in the patient with JCA a few regions with variably dense PMN infiltrates were observed. Cathepsin G, elastase and esterase activity were found in and around the PMN. In one of the three patients with seropositive RA the adjacent cartilage-pannus junction exhibited distinct staining for cathepsin G and elastase, but not for IgG/C3 and proteinase inhibitors. The findings suggest that cathepsin G and elastase from PMN are involved in the breakdown of rheumatoid articular cartilage in the presence, as well as in the absence, of entrapped immune-complex-like material, and that proteinase inhibitors are often lacking in such regions.This paper is dedicated to Prof. Dr. A. Böni and Prof. Dr. H. Mathies for their 75th and 70th birthdays