Pathogenic antibody recognition of cartilage

Area of Science:

• Immunology
• Rheumatology
• Orthopedics

Background:

• Antibodies against cartilage proteins, particularly collagen type II (CII), are prevalent in rheumatoid arthritis (RA) patients.
• These antibodies are implicated in arthritis induction and progression, even preceding clinical disease in animal models.
• Anti-CII antibodies can directly cause cartilage and bone destruction, independent of other inflammatory factors.

Purpose of the Study:

• To investigate the role of antibodies targeting cartilage proteins in rheumatoid arthritis (RA) pathogenesis.
• To explore the arthritogenic potential of antibodies to citrullinated protein antigens and rheumatoid factor.
• To assess the therapeutic implications of antibody modification for cartilage protection in RA.

Main Methods:

• Analysis of antibody prevalence in RA patient sera and synovial fluids.
• Induction of arthritis in naive mice using anti-CII antibodies.
• Evaluation of monoclonal antibodies targeting citrullinated cartilage proteins for cartilage binding and arthritis mediation.
• Assessment of the effects of enzymatic cleavage or modification of pathogenic IgG antibodies on cartilage protection.

Main Results:

• Antibodies against cartilage proteins, especially anti-CII, induce arthritis and cause significant cartilage and bone destruction in mice.
• Monoclonal antibodies to citrulline-modified cartilage proteins bind to cartilage and synovial tissue, mediating arthritis.
• Some pathogenic anti-CII antibodies exhibit rheumatoid factor-like activity, suggesting a role in RA.
• Enzymatic modification of pathogenic IgG antibodies protects cartilage from inflammatory damage.

Conclusions:

• Antibodies targeting cartilage proteins are key drivers of RA pathogenesis and joint destruction.
• Both anti-CII and antibodies to citrullinated proteins may contribute to RA, with potential overlapping mechanisms.
• Modifying pathogenic antibodies presents a promising therapeutic avenue for protecting cartilage in RA.