title: Pemphigus autoantibodies generated through somatic mutations target the desmoglein-3 cis-interface.
abstract: Pemphigus vulgaris (PV) is an autoimmune blistering disease of skin and mucous membranes caused by autoantibodies to the desmoglein (DSG) family proteins DSG3 and DSG1, leading to loss of keratinocyte cell adhesion. To learn more about pathogenic PV autoantibodies, we isolated 15 IgG antibodies specific for DSG3 from 2 PV patients. Three antibodies disrupted keratinocyte monolayers in vitro, and 2 were pathogenic in a passive transfer model in neonatal mice. The epitopes recognized by the pathogenic antibodies were mapped to the DSG3 extracellular 1 (EC1) and EC2 subdomains, regions involved in cis-adhesive interactions. Using a site-specific serological assay, we found that the cis-adhesive interface on EC1 recognized by the pathogenic antibody PVA224 is the primary target of the autoantibodies present in the serum of PV patients. The autoantibodies isolated used different heavy- and light-chain variable region genes and carried high levels of somatic mutations in complementary-determining regions, consistent with antigenic selection. Remarkably, binding to DSG3 was lost when somatic mutations were reverted to the germline sequence. These findings identify the cis-adhesive interface of DSG3 as the immunodominant region targeted by pathogenic antibodies in PV and indicate that autoreactivity relies on somatic mutations generated in the response to an antigen unrelated to DSG3.
authors.affiliation: Molecular and cell Biology Laboratory, Istituto Dermopatico dell'Immacolata, IDI-IRCCS, Rome, Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Di Zenzo
authors.forename: Giulia
authors.initials: G
authors.lastname: Di Lullo
authors.forename: Davide
authors.initials: D
authors.lastname: Corti
authors.forename: Valentina
authors.initials: V
authors.lastname: Calabresi
authors.forename: Anna
authors.initials: A
authors.lastname: Sinistro
authors.forename: Fabrizia
authors.initials: F
authors.lastname: Vanzetta
authors.forename: Biagio
authors.initials: B
authors.lastname: Didona
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Cianchini
authors.forename: Michael
authors.initials: M
authors.lastname: Hertl
authors.forename: Rudiger
authors.initials: R
authors.lastname: Eming
authors.forename: Masayuki
authors.initials: M
authors.lastname: Amagai
authors.forename: Bungo
authors.initials: B
authors.lastname: Ohyama
authors.forename: Takashi
authors.initials: T
authors.lastname: Hashimoto
authors.forename: Jerry
authors.initials: J
authors.lastname: Sloostra
authors.forename: Federica
authors.initials: F
authors.lastname: Sallusto
authors.forename: Giovanna
authors.initials: G
authors.lastname: Zambruno
authors.forename: Antonio
authors.initials: A
authors.lastname: Lanzavecchia
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000831:Animals, Newborn; D000937:Antigen-Antibody Reactions; D001323:Autoantibodies / Q000276:immunology*; D001324:Autoantigens / Q000737:chemistry / Q000276:immunology*; D002478:Cells, Cultured; D022801:Complementarity Determining Regions / Q000276:immunology; D051184:Desmoglein 3 / Q000737:chemistry / Q000276:immunology*; D000939:Epitopes / Q000737:chemistry / Q000276:immunology; D006801:Humans; D007116:Immunization, Passive; D007074:Immunoglobulin G / Q000276:immunology*; D007135:Immunoglobulin Variable Region / Q000235:genetics; D015603:Keratinocytes / Q000276:immunology; D051379:Mice; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D010392:Pemphigus / Q000276:immunology*; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D027041:Somatic Hypermutation, Immunoglobulin
chemical_list: D001323:Autoantibodies; D001324:Autoantigens; D022801:Complementarity Determining Regions; C071894:DSG3 protein, human; D051184:Desmoglein 3; D000939:Epitopes; D007074:Immunoglobulin G; D007135:Immunoglobulin Variable Region