Rheumatoid factor IgM autoantibodies control IgG homeostasis

Area of Science:

• Immunology
• Autoimmunity
• Rheumatology

Background:

• Rheumatoid arthritis involves joint inflammation driven by autoantibodies.
• Elevated IgM antibodies binding to IgG, known as rheumatoid factor (RF), are common in severe rheumatoid arthritis.
• The precise role of RF in disease pathogenesis remains unclear.

Purpose of the Study:

• To investigate the biological function of rheumatoid factor (RF) antibodies.
• To determine how RF affinity and specificity influence IgG homeostasis.
• To explore the therapeutic potential of modulating RF activity in autoimmune diseases.

Main Methods:

• Characterization of RFs based on affinity and polyreactivity.
• In vivo assessment of RF effects on IgG stabilization and neutralization.
• Analysis of the balance between IgM-mediated IgG degradation and stabilization.

Main Results:

• High-affinity, mono-specific RFs stabilize IgG.
• Low-affinity, polyreactive RFs neutralize IgG in vivo.
• A disbalance in IgM-mediated IgG regulation is implicated in autoimmune disease onset and progression.

Conclusions:

• Autoreactive IgM antibodies targeting IgG play a key role in regulating IgG homeostasis.
• Dysregulation of IgG homeostasis by RFs may contribute to autoimmune diseases.
• Therapeutic strategies using low-affinity anti-IgG IgM could restore balance and treat autoimmune diseases.