Cartilage oligomeric matrix protein specific antibodies are pathogenic

Area of Science:

• Immunology
• Rheumatology
• Biochemistry

Background:

• Cartilage oligomeric matrix protein (COMP) is a crucial non-collagenous component of cartilage.
• A novel mouse model for rheumatoid arthritis (RA) utilizing COMP was previously established.
• This study investigates the epitope specificity and immunopathogenicity of COMP-specific monoclonal antibodies (mAbs).

Purpose of the Study:

• To map immunodominant B cell epitopes on the COMP molecule.
• To characterize the pathogenicity of COMP-specific monoclonal antibodies (mAbs).
• To explore the role of anti-COMP antibodies in the development of autoimmune arthritis.

Main Methods:

• Utilized a novel enzyme-linked immunosorbent assay (ELISA) with full-length and fragmented mouse COMP.
• Generated 18 distinct anti-COMP mAbs.
• Assessed mAb pathogenicity through passive transfer experiments in a mouse model.

Main Results:

• Identified four antigenic domains on COMP, with a preference for the epidermal growth factor (EGF)-like domain.
• Some anti-COMP mAbs interacted with native COMP found in cartilage and synovium.
• Passive transfer of COMP-specific mAbs exacerbated arthritis; five mAbs together induced arthritis in naive mice.

Conclusions:

• Established the specificities of mAbs targeting COMP and their role in arthritis development.
• Findings enhance understanding of autoantibody-mediated immunopathologies in rheumatoid arthritis (RA).
• Provides insights into autoimmune disorders involving COMP autoantibodies.