Single-Cell Analysis Suggests that Ongoing Affinity Maturation Drives the Emergence of Pemphigus Vulgaris Autoimmune Disease

Abstract

SUMMARY Pemphigus vulgaris (PV) is an autoimmune disease characterized by blistering sores on skin and mucosal membranes, caused by autoantibodies primarily targeting the cellular adhesion protein, desmoglein-3 (Dsg3). To better understand how Dsg3-specific autoantibodies develop and cause disease in humans, we performed a cross-sectional study of PV patients before and after treatment to track relevant cellular responses underlying disease pathogenesis, and we provide an in-depth analysis of two patients by generating a panel of mAbs from single Dsg3-specific memory B cells (MBCs). Additionally, we analyzed a paired sample from one patient collected 15-months prior to disease diagnosis. We find that Dsg3-specific MBCs have an activated phenotype and show signs of ongoing affinity maturation and clonal selection. Monoclonal antibodies (mAbs) with pathogenic activity primarily target epitopes in the extracellular domains EC1 and EC2 of Dsg3, though they can also bind to the EC4 domain. Combining antibodies targeting different epitopes synergistically enhances in vitro pathogenicity.

Affinity maturation is required for pathogenic monovalent IgG4 autoantibody development in myasthenia gravis

“…Examples include viral infections ( Bonsignori et al, 2018 ; Corti et al, 2010 , 2011 ; Pappas et al, 2014 ) and responses to influenza hemagglutinin, wherein unmutated revertants of virus antigen–specific mAbs, in some instances, demonstrate binding activity. These scenarios, however, must be carefully considered, as there are some limited examples of binding by germline-reverted autoantibodies ( Cho et al, 2019 ; Wenke et al, 2019 ). These collective findings may point toward the limitations of the approaches available to measure antibody–antigen interactions, including ELISAs and live CBAs, neither of which may be sufficiently sensitive to measure low-affinity interactions or accurately emulate the antigen/autoantigen binding to the BCR of naive B cells in situ, such as lymphoid tissue.…”

Murine gammaherpesvirus infection is skewed toward Igλ+ B cells expressing a specific heavy chain V-segment

“…Whatever the mechanism, inhibition of SHM and affinity maturation would inhibit production of highly specific antibodies, which may be an important aspect of how MHV68 suppresses the specific antibody response. It has been shown that highly specific, broadly neutralizing antibodies to HIV [43], as well as autoantibodies cloned from systemic lupus erythematosus patients [44] and pemphigus vulgaris patients [45], lose specificity upon reversion to their germline sequence. Furthermore, this data suggests that SHM may not be a good indicator to distinguish shortlived, extra-follicular plasma cells from germinal center derived, long-lived plasma cells induced during gammaherpesvirus infection.…”

Autoimmune Pemphigus: Latest Advances and Emerging Therapies

“…However, other isotypes may also be pathogenic in some variants or circumstances (Payne et al, 2005;Saleh et al, 2015). Interesting new data have revealed that DSG3-specific memory B cells have an activated phenotype and show signs of ongoing affinity maturation and clonal selection (Cho et al, 2019).…”