Strong Clonal Relatedness between Serum and Gut IgA despite Different Plasma Cell Origins

Abstract

SummaryMucosal antigens induce generation of lamina propria plasma cells (PCs) that secrete dimeric immunoglobulin A (IgA) destined for transport across the epithelium. In addition, blood contains monomeric IgA. To study the relationship between mucosal and systemic antibody responses, we took advantage of celiac disease patient samples for isolation of gut PCs as well as serum IgA and IgG reactive with a gluten-derived peptide or the autoantigen transglutaminase 2. Proteomic analysis of serum IgA revealed antigen-specific V-gene preferences, which matched those found in gut PCs. Further, gut PC CDR-H3 sequences were abundant in serum IgA but also detectable in serum IgG. Our data indicate that the same B cell clones that give rise to gut PCs also contribute to the serum antibody pool. However, serum IgA antibodies had a molecular composition distinct from that of IgA antibodies secreted in the gut, suggesting that individual B cell clones give rise to different PC populations.

Longevity, clonal relationship and transcriptional program of celiac disease-specific plasma cells

“…50 Beyond this known preference, we observed a further skewed IgA1/IgA2 usage in TG2specific PCs compared to PCs of unknown specificity in line with a previous report from our group. 22 While many clone groups contained only IgA1-or IgA2-expressing PCs, we also observed several clones spanning IgA1, IgA2 and even IgM. Although isotype class switching has been studied over the years, 65 many details are still unclear.…”

“…7). Although the BCR repertoires of TG2-specific PCs in CeD have been extensively studied, 19,20,22 fewer and more small-scale studies have been done for DGP-specific PCs. 10,21 Here, by looking at the reconstructed BCR sequences of TG2-specific and DGP-specific PCs, we observed a similar skewing of variable (V)-gene usage as previously reported.…”

“…10,21 Here, by looking at the reconstructed BCR sequences of TG2-specific and DGP-specific PCs, we observed a similar skewing of variable (V)-gene usage as previously reported. 10,[19][20][21][22] TG2-specific PCs preferentially used IGHV5-51, IGHV1-69 and IGHV3-43, with 66±3.9% of unique clones pairing with Igk (in particular V-genes IGKV1-5 and IGKV3-11). For DGP-specific PCs, we identified stereotypical V-gene pairing between IGHV3-74 and IGKV4-1, which has not been previously reported.…”

“…High-throughput sequencing technologies have revolutionized the profiling of immune receptor repertoires in health and disease (AIRR-seq), 16,17 and we have previously applied these technologies to dissect the repertoire of disease-specific PCs in CeD. 10,[18][19][20][21][22] However, little is known about the transcriptional state of these cells. The development of single-cell RNA-seq (scRNA-seq) protocols provides a unique tool to identify and characterize cell subsets according to their full transcriptional profile.…”

Precipitating anti-dsDNA peptide repertoires in lupus

“…Molecular profiling of anti-mtDNA will be of particular interest, given the recent emphasis on oxidized, mitochondrial DNA in expelled neutrophil extracellular traps (NETs) as pathogenic factors in lupus and potential drivers of anti-dsDNA production [36,37]. MS-based antibody proteomics is a powerful serumbased approach for mapping V-gene usage and identifying shared mutated IgV peptides of diagnostic utility at the level of protein expression [19,38]. However, the highresolution bottom-up de novo LC-MS/MS-IgV peptidemapping workflow used herein cannot capture the complete repertoire of a serum antibody, most notably clonotypical HCDR3 regions, as these peptides are generally hydrophobic, ionize and fragment poorly and lack published HCDR3 matching databases [39].…”