Open AccessModulation of fibroblast‐mediated cartilage degradation by articular chondrocytes in rheumatoid arthritis
Author(s) -
Pap Thomas,
Van Der Laan Willemijn H.,
Aupperle Karlfried R.,
Gay Renate E.,
Verheijen Jan H.,
Firestein Gary S.,
Gay Steffen,
Neidhart Michel
Publication year - 2000
Publication title -
arthritis & rheumatism
Language(s) - English
Resource type - Journals
eISSN - 1529-0131
pISSN - 0004-3591
DOI - 10.1002/1529-0131(200011)43:11<2531::aid-anr21>3.0.co;2-v
Subject(s) - cartilage , cycloheximide , rheumatoid arthritis , arthritis , in vitro , fibroblast , osteoarthritis , matrix (chemical analysis) , tumor necrosis factor alpha , chondrocyte , chemistry , pathology , medicine , immunology , anatomy , protein biosynthesis , biochemistry , alternative medicine , chromatography
Objective To determine the role of chondrocytes and factors released from chondrocytes in cartilage destruction by fibroblast‐like synoviocytes (FLS) derived from patients with rheumatoid arthritis (RA). Methods RA FLS from 2 patients were implanted into SCID mice, together with fresh articular cartilage or with cartilage that had been stored for 24 hours at 4°C or at 37°C. The invasion of the same RA FLS into the fresh and stored cartilage was compared histologically using a semiquantitative scoring system. In addition, we investigated whether protein synthesis in chondrocytes affects the invasion of RA FLS in vitro. A 3‐dimensional cartilage‐like matrix formed by cultured chondrocytes was labeled with 35 S. After formation of the cartilage‐like matrix, protein synthesis was blocked with cycloheximide. The invasion of RA FLS from 6 patients into cycloheximide‐treated and untreated matrix was assessed by measuring the released radioactivity in coculture with and without interleukin‐1β (IL‐1β) and tumor necrosis factor α (TNFα). Results The SCID mouse experiments showed a significant invasion of RA FLS into the cartilage (overall mean score 3.2) but revealed significant differences when the invasion of the same RA FLS into fresh and stored cartilage was compared. RA FLS that were implanted with fresh articular cartilage showed a significantly higher invasiveness than those implanted with pieces of cartilage that had been stored for 24 hours (overall mean score 2.3). Storage at 37°C and 4°C resulted in the same reduction of invasion (35% and 37%, respectively). In the in vitro experiments, RA FLS rapidly destroyed the cartilage‐like matrix. Blocking of chondrocyte protein biosynthesis significantly decreased the invasion of RA FLS, as shown by a decreased release of radioactivity. Addition of IL‐1β, but not TNFα, to the cocultures partially restored the invasiveness of RA FLS. Conclusion These data underline the value of the SCID mouse in vivo model of rheumatoid cartilage destruction and demonstrate that chondrocytes contribute significantly to the degradation of cartilage by releasing factors that stimulate RA FLS. Among those, IL‐1β–mediated mechanisms might be of particular importance.