Immunologic modulation of cartilage metabolism

Area of Science:

• Biomedical Science
• Orthopedics
• Cell Biology

Background:

• Cartilage health depends on balanced chondrocyte anabolic and catabolic activities.
• Osteoarthritis (OA) involves perturbed metabolic homeostasis in cartilage.
• Mononuclear cell infiltration in synovial tissue and bone marrow is characteristic of OA.

Purpose of the Study:

• To investigate the role of cytokines from infiltrating mononuclear cells in OA pathogenesis.
• To understand how these cytokines affect chondrocyte metabolism and extracellular matrix production.

Main Methods:

• Analysis of cytokine effects on chondrocyte proteoglycan, collagen, and non-collagen protein synthesis.
• Assessment of cytokine-induced synthesis and release of chondrocyte proteinases.
• Comparison of factors from synovial tissue in different forms of OA.

Main Results:

• Cytokines from T lymphocytes and monocytes alter chondrocyte protein synthesis qualitatively and suppress it reversibly.
• These cytokines also induce chondrocyte synthesis and release of proteinases.
• Synovial tissue in OA produces factors with similar metabolic regulatory activities.

Conclusions:

• Infiltrating mononuclear cells and their derived cytokines significantly contribute to cartilage degradation in OA.
• Cytokine-induced suppression of anabolism and induction of catabolism in chondrocytes are key mechanisms in OA.
• Synovial tissue is a source of detrimental factors affecting cartilage metabolism in OA.