CVID-Associated B Cell Activating Factor Receptor Variants Change Receptor Oligomerization, Ligand Binding, and...

Area of Science:

• Immunology
• Molecular Biology
• Genetics

Background:

• The B cell activating factor receptor (BAFFR) is crucial for mature B cell survival and function.
• Mutations in BAFFR are associated with immunodeficiency, autoimmunity, and lymphoma.
• The functional impact of specific BAFFR variants remains largely uncharacterized.

Purpose of the Study:

• To investigate the functional consequences of various BAFFR missense variants.
• To analyze the effects of these variants on BAFFR oligomerization, signaling, and ectodomain shedding.
• To determine the clinical relevance of identified BAFFR variants in primary antibody deficiencies.

Main Methods:

• Genetic association studies were conducted.
• A cellular system using lentiviral gene transfer in DG-75 cells was established to express BAFFR variants.
• Functional analyses included assessment of BAFF binding, spontaneous oligomerization, NF-κB2 and AKT activation, ERK1/2 phosphorylation, and BAFF-induced ectodomain shedding.

Main Results:

• Several BAFFR variants (P21R, A52T, G64V, DUP92-95, P146S) exhibited impaired BAFF binding, oligomerization, or signaling pathways (NF-κB2, AKT, ERK1/2).
• The P21R variant uniquely affected BAFF-induced ectodomain shedding.
• All analyzed variants altered BAFFR function, with P21R showing a positive correlation with common variable immunodeficiency (CVID).

Conclusions:

• BAFFR variants disrupt B cell survival pathways and can act as modifiers in immune disorders.
• The P21R variant is clinically significant, correlating with CVID and affecting multiple BAFFR functions.
• Understanding these variants is crucial for diagnosing and potentially treating primary antibody deficiencies and related conditions.