Proteomic Analysis of Pemphigus Autoantibodies Indicates a Larger, More Diverse, and More Dynamic Repertoire than Determined by B Cell Genetics

Abstract

Summary In autoantibody-mediated diseases such as pemphigus serum antibodies lead to disease. Genetic analysis of B cells has allowed characterization of antibody repertoires in such diseases but would be complemented by proteomic analysis of serum autoantibodies. Here we show using proteomic analysis that the serum autoantibody repertoire in pemphigus is much more polyclonal than found by genetic studies of B cells. In addition many B cells encode pemphigus autoantibodies that are not secreted into the serum. Heavy chain variable gene usage of serum autoantibodies is not shared among patients, implying targeting of the coded proteins will not be a useful therapeutic strategy. Analysis of autoantibodies over years in individual patients indicates that many antibody clones persist but the proportion of each changes. These studies indicate a dynamic and diverse autoantibody response not revealed by genetic studies, and explain why similar overall autoantibody titers may give variable disease activity.

Walnut antigens can trigger autoantibody development in patients with pemphigus vulgaris through a “hit-and-run” mechanism

“…All 8 pathogenic mAbs were generated from peripheral blood samples of patients with PV and might not well represent the circulating diseaseinducing pathogenic antibodies in sera of patients with pemphigus because of sampling bias. 26,54 In addition, autoantibody-associated B cells or plasma cells are more abundant in lesional or perilesional skin of patients with pemphigus. 55 Further studies using both pathogenic and revertant/germline mAbs generated from these tissues might better represent the PV-associated autoantibodies in the circulation of patients with pemphigus.…”

Recent advances in the understanding and treatment of pemphigus and pemphigoid

“…However, proteomic analysis of pemphigus autoantibodies gave us a different perspective by indicating that changes in the proportions of autoantibodies occur over time 20 . Further research is necessary to fully delineate the mechanisms of autoantibody production in pemphigus.…”

Serum proteomics expands on high-affinity antibodies in immunized rabbits than deep B-cell repertoire sequencing alone

“…High-throughput sequencing of antibody transcripts or the rearranged immunoglobulin (Ig) locus in B-cell populations (Rep-seq) has uncovered a vast diversity of antibodies. Rep-seq has shed light on many mechanisms of immunity ranging from understanding quiescent stasis [16], activation in response to vaccines [15,21], vaccine response differences in identical twins [37], response to chronic HIV infection [41] and immunization [14], engagement within the tumor microenvironment [5], and breaking of self-tolerance for autoimmune diseases [35,7]. However, the Ig transcripts from cells sampled from various compartments and tissues are only a small component of the humoral immune response.…”

“…argued that the LC-MS/MS limit of detection is at the 0.1nM theoretical ceiling for neutralization affinity of antibodies, and their immunoproteogenomic approach sufficiently captures the relevant antibody clonotypes in the serological compartment [23]. Additional groups have applied immunoproteogenomics to llama [11], CMV infected human [31], and human pemphigus [7].…”