Autoantibodies in systemic lupus erythematosus

Area of Science:

• Immunology
• Rheumatology
• Molecular Biology

Background:

• Systemic lupus erythematosus (SLE) is characterized by a diverse range of autoantibodies.
• The origins and cross-reactivity of autoantibodies, such as anti-double-stranded DNA (anti-dsDNA) antibodies, are critical in understanding SLE pathogenesis.
• Specific autoantibodies are associated with distinct clinical manifestations and complications of SLE.

Purpose of the Study:

• To explore the antigenic origins and cross-reactivity patterns of lupus autoantibodies.
• To investigate the clinical significance of various autoantibodies in SLE patients and their offspring.
• To examine the role of cofactors in antiphospholipid antibody reactivity.

Main Methods:

• Analysis of antibody homology with germline DNA.
• Assessment of antigenicity of bacterial versus mammalian DNA in murine models (NZB/NZW mice).
• Evaluation of antibody cross-reactivity with cellular components (ribonucleoproteins, ribosomal P proteins, DNA-histone complexes).
• Correlation of autoantibodies with clinical features (neuropsychiatric, renal, hepatic involvement, neonatal lupus, congenital heart block).
• Investigation of protein cofactor requirements for antiphospholipid antibody binding.

Main Results:

• Lupus anti-DNA antibodies may exhibit higher germline homology; bacterial DNA is more antigenic in NZB/NZW mice.
• High-affinity anti-dsDNA antibodies cross-react with small nuclear ribonucleoprotein and ribosomal P proteins, potentially entering live cells.
• Antibodies to ribosomal P proteins correlate with neuropsychiatric, renal, and hepatic lupus.
• IgG antibodies to (H2A-H2B)-DNA complexes precede procainamide-induced lupus.
• Maternal autoantibodies to La/Ro peptides predict neonatal lupus and congenital heart block in children.
• Perinuclear antineutrophil cytoplasmic antibodies are found in 25% of SLE patients, independent of anti-DNA or disease activity.
• Anionic phospholipid antibodies require beta 2-glycoprotein I, while anti-phosphatidylethanolamine antibodies require kininogen.
• Antibodies to phospholipid-free beta 2-glycoprotein I are more strongly associated with clinical antiphospholipid syndrome than antiphospholipid antibodies.

Conclusions:

• Lupus autoantibodies display complex origins, cross-reactivity, and significant clinical associations.
• Specific autoantibodies serve as important biomarkers for SLE manifestations and risks.
• Understanding cofactor requirements refines the understanding of antiphospholipid antibody-mediated pathology.