Dysregulation of B Cell Repertoire Formation in Myasthenia Gravis Patients Revealed through Deep Sequencing

• Published in: The Journal of immunology (1950) Vol. 198; no. 4; pp. 1460 - 1473
• Main Authors: Vander Heiden, Jason A, Stathopoulos, Panos, Zhou, Julian Q, Chen, Luan, Gilbert, Tamara J, Bolen, Christopher R, Barohn, Richard J, Dimachkie, Mazen M, Ciafaloni, Emma, Broering, Teresa J, Vigneault, Francois, Nowak, Richard J, Kleinstein, Steven H, O’Connor, Kevin C
• Format: Journal Article
• Language: English
• Published: United States American Association of Immunologists 15.02.2017
• Subjects: Acetylcholine; Acetylcholine receptors; Adolescent; Adult; Autoantibodies; Autoantibodies - immunology; B-Lymphocytes - immunology; B-Lymphocytes - pathology; B-Lymphocytes - physiology; Clonal selection; Complementarity-determining region 3; Defects; Female; High-Throughput Nucleotide Sequencing - methods; Humans; Immune Tolerance; Immunologic Memory; Immunological memory; Immunological tolerance; Lymphocytes B; Male; Middle Aged; MUSK protein; Mutation; Myasthenia gravis; Myasthenia Gravis - immunology; Myasthenia Gravis - physiopathology; Neuromuscular junctions; Physicochemical properties; Positive selection; Protein Kinases - immunology; Receptor Protein-Tyrosine Kinases - immunology; Receptors, Antigen, B-Cell - genetics; Receptors, Antigen, B-Cell - immunology; Receptors, Cholinergic - immunology; Young Adult
• ISSN: 0022-1767; 1550-6606; 1550-6606
• DOI: 10.4049/jimmunol.1601415

Myasthenia gravis (MG) is a prototypical B cell-mediated autoimmune disease affecting 20–50 people per 100,000. The majority of patients fall into two clinically distinguishable types based on whether they produce autoantibodies targeting the acetylcholine receptor (AChR-MG) or muscle specific kinase (MuSK-MG). The autoantibodies are pathogenic, but whether their generation is associated with broader defects in the B cell repertoire is unknown. To address this question, we performed deep sequencing of the BCR repertoire of AChR-MG, MuSK-MG, and healthy subjects to generate ∼518,000 unique VH and VL sequences from sorted naive and memory B cell populations. AChR-MG and MuSK-MG subjects displayed distinct gene segment usage biases in both VH and VL sequences within the naive and memory compartments. The memory compartment of AChR-MG was further characterized by reduced positive selection of somatic mutations in the VH CDR and altered VH CDR3 physicochemical properties. The VL repertoire of MuSK-MG was specifically characterized by reduced V-J segment distance in recombined sequences, suggesting diminished VL receptor editing during B cell development. Our results identify large-scale abnormalities in both the naive and memory B cell repertoires. Particular abnormalities were unique to either AChR-MG or MuSK-MG, indicating that the repertoires reflect the distinct properties of the subtypes. These repertoire abnormalities are consistent with previously observed defects in B cell tolerance checkpoints in MG, thereby offering additional insight regarding the impact of tolerance defects on peripheral autoimmune repertoires. These collective findings point toward a deformed B cell repertoire as a fundamental component of MG.