IgG reactivity against non‐conformational NH₂‐terminal epitopes of the desmoglein 3 ectodomain relates to clinical activity and phenotype of pemphigus vulgaris

Abstract

Pemphigus vulgaris (PV) is an autoimmune disease caused by immunoglobulin G (IgG) autoantibodies against the desmosomal adhesion molecules, desmoglein (Dsg)3 and Dsg1. The aim of the study was to relate IgG reactivity of 123 PV sera and 40 control sera against NH(2)-terminal non-conformational epitopes of Dsg3 and Dsg1 with disease activity and clinical phenotype by enzyme-linked immunosorbent assay. The results show that (i) the overall reactivity and the titres of IgG reactive with the Dsg3 ectodomain, Dsg3(1-566), significantly correlated with the disease activity of the PV patients; (ii) IgG reactivity against the NH(2)-terminus of Dsg3, Dsg3(1-161), was associated with active PV while there was no direct correlation between the IgG titres and the disease activity; (iii) IgG reactivity against the NH(2)-terminus of Dsg3, Dsg3(1-161), was associated with mucosal and mucocutaneous PV; (iv) IgG titres against a small stretch of the NH(2)-terminus of Dsg3, Dsg3(25-88), were associated with active PV; and (v) IgG in the PV sera detected non-conformational epitopes in addition to the previously identified conformation-dependent epitopes of the Dsg3 and Dsg1 ectodomains.

150thAnniversary Series: Desmosomes and Autoimmune Disease, Perspective of Dynamic Desmosome Remodeling and Its Impairments in Pemphigus

“…The steric hindrance concept has been widely accepted, because PF and PV sera contain signifi cant amounts of antibodies against the amino-terminal part of the EC 1 domain (Futei et al, 2000;Hacker-Foegen et al, 2003), which is recognized as the most important binding domain for trans-interaction of desmogleins in desmosomes (Al-Amoudi et al, 2007;Yamagami et al, 2010), and because that the intensity of autoantibody reactivity to EC 1 of Dsg 3 correlates well with the disease severity of PV patients, although this is not the case in antibodies, which demonstrate a broader range of reactivity to other domains (Amagai et al, 1992;Muller et al, 2006). In addition, the data obtained via AFM experiments demonstrate that under cell-free conditions, IgG fractions of PV patients interfere with Dsg3 trans-interaction (Heupel et al, 2008;Spindler et al, 2009).…”

Pathogenic IgG Antibodies against Desmoglein 3 in Pemphigus Vulgaris Are Regulated by HLA-DRB1*04:02–Restricted T Cells

“…The in vivo-induced anti-human Dsg3-reactive IgG Abs recognized the same spectrum of epitopes as IgG autoantibodies from PV sera (20,25). After the first immunization with human Dsg3, mouse sera preferentially reacted with the COOH-terminal Dsg3(EC5) subdomain and, after additional immunizations, also with the N-terminal Dsg3(EC1) and Dsg3(EC2) domains, which contain the major pathogenic B cell epitopes (Fig.…”

“…1B). Blood samples were taken to analyze anti-Dsg3 IgG by ELISA as described previously (20). For the induction of Dsg3-reactive T cell responses, mice were injected s.c. into the foot paws with human Dsg3 protein and peptides (20-40mg), respectively, in adjuvant (IFA or TiterMax) (Sigma-Aldrich) on day 0, and draining popliteal and inguinal lymph nodes were harvested on days 7-10 (Supplemental Fig.…”

“…Mouse sera were diluted 1:20 and analyzed for anti-Dsg3 IgG by ELISA as described previously (20). In addition, two commercial human Dsg3 ELISA kits were also used (MBL, Nagoya, Japan; Euroimmun, L€ ubeck, Germany) and were modified by using an anti-mouse IgG HRP-conjugated secondary Ab.…”

“…Human and mouse Dsg3 recombinants linked to an E tag and a 63 histidine tag were produced and purified by affinity chromatography as described previously (Table I) (8,(18)(19)(20). Fifteen-and 17-mer Dsg3 peptides were synthesized by F-moc chemistry resulting in a .95% purity (Table III) (peptides & elephants, Potsdam, Germany) and were solubilized in DMSO acetic acid buffer (stock concentration, 2 mg/ml).…”