Epitope spreading induced by immunization with synthetic SSB peptides

Area of Science:

• Immunology
• Autoimmunity
• Connective Tissue Diseases

Background:

• Sjogren's syndrome type B (SSB)/La antibodies are associated with connective tissue diseases.
• Double-stranded deoxyribonucleic acid (dsDNA) antibodies are characteristic of systemic lupus erythematosus (SLE).
• The relationship between SSB and dsDNA antibodies is not well understood.

Purpose of the Study:

• To investigate antibody production profiles in rabbits immunized with synthetic SSB peptides alone or with dsDNA.
• To explore the potential link and immune response interactions between SSB and dsDNA autoantibodies.

Main Methods:

• Synthesis of a specific SSB peptide (214-225aa) using solid-phase peptide synthesis.
• Immunization of rabbits with SSB peptides, dsDNA, or a combination of both, alongside control groups.
• Measurement of SSB peptide antibodies via ELISA, and ENA/dsDNA antibodies using immunoblotting and immunofluorescence.

Main Results:

• Rabbits immunized with SSB peptides alone or with dsDNA produced specific anti-SSB peptide antibodies.
• The SSB peptide antibody titer was significantly higher in the coimmunization group (SSB + dsDNA) compared to the SSB alone group.
• Antibodies against ribonucleoprotein (RNP), Smith, and/or dsDNA were detected in rabbits from the coimmunization group, indicating epitope spreading.

Conclusions:

• SSB antibodies can be produced following immunization with SSB peptides or SSB peptides combined with dsDNA.
• Coimmunization with SSB peptides and dsDNA leads to higher SSB antibody titers.
• Coimmunization is associated with epitope spreading, suggesting a potential mechanism linking these autoantibodies in autoimmune diseases.