IgV peptide mapping of native Ro60 autoantibody proteomes in primary Sjögren's syndrome reveals molecular markers of Ro/La diversification.
We have used high-resolution mass spectrometry to sequence precipitating anti-Ro60 proteomes from sera of patients with primary Sjögren's syndrome and compare immunoglobulin variable-region (IgV) peptide signatures in Ro/La autoantibody subsets. Anti-Ro60 were purified by elution from native Ro60-coated ELISA plates and subjected to combined de novo amino acid sequencing and database matching. Monospecific anti-Ro60 Igs comprised dominant public and minor private sets of IgG1 kappa and lambda restricted heavy and light chains. Specific IgV amino acid substitutions stratified anti-Ro60 from anti-Ro60/La responses, providing a molecular fingerprint of Ro60/La determinant spreading and suggesting that different forms of Ro60 antigen drive these responses. Sequencing of linked anti-Ro52 proteomes from individual patients and comparison with their anti-Ro60 partners revealed sharing of a dominant IGHV3-23/IGKV3-20 paired clonotype but with divergent IgV mutational signatures. In summary, anti-Ro60 IgV peptide mapping provides insights into Ro/La autoantibody diversification and reveals serum-based molecular markers of humoral Ro60 autoimmunity.
Department of Immunology, Flinders Medical Centre and Flinders University, SA Pathology, Bedford Park 5042, South Australia, Australia.
Jing J
JJ
Wang
Department of Immunology, Flinders Medical Centre and Flinders University, SA Pathology, Bedford Park 5042, South Australia, Australia; Department of Microbiology and Immunology, Sultan Qaboos University Hospital, Muscat 123, Oman.
Mahmood A
MA
Al Kindi
Department of Immunology, Flinders Medical Centre and Flinders University, SA Pathology, Bedford Park 5042, South Australia, Australia; Flinders Proteomics Facility, Flinders University, Bedford Park 5042, South Australia, Australia.
Alex D
AD
Colella
Flinders Proteomics Facility, Flinders University, Bedford Park 5042, South Australia, Australia.
Lukah
L
Dykes
Department of Immunology, Flinders Medical Centre and Flinders University, SA Pathology, Bedford Park 5042, South Australia, Australia.
Michael W
MW
Jackson
Flinders Proteomics Facility, Flinders University, Bedford Park 5042, South Australia, Australia.
Tim K
TK
Chataway
Garvan Institute of Medical Research, Immunology Division, Immunogenomics Laboratory, 384 Victoria Street, Darlinghurst, NSW 2010, Australia.
Joanne H
JH
Reed
Department of Immunology, Flinders Medical Centre and Flinders University, SA Pathology, Bedford Park 5042, South Australia, Australia. Electronic address: t.gordon@flinders.edu.au.
Tom P
TP
Gordon
D001323:Autoantibodies / Q000097:blood / Q000276:immunology*; D001324:Autoantigens / Q000276:immunology*; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood / Q000276:immunology; D007135:Immunoglobulin Variable Region / Q000276:immunology*; D010449:Peptide Mapping; D020543:Proteome; D020733:RNA, Small Cytoplasmic / Q000276:immunology*; D012261:Ribonucleoproteins / Q000276:immunology*; D012859:Sjogren's Syndrome / Q000097:blood / Q000276:immunology*; D000099207:SS-A Antigen
D001323:Autoantibodies; D001324:Autoantigens; D007074:Immunoglobulin G; D007135:Immunoglobulin Variable Region; D020543:Proteome; D020733:RNA, Small Cytoplasmic; D012261:Ribonucleoproteins; C116006:RO60 protein, human; D000099207:SS-A Antigen
Autoantibody; Mass spectrometry sequencing; Ro60; Sjögren's syndrome