TY - JOUR
T1 - Variable domain N-linked glycosylation and negative surface charge are key features of monoclonal ACPA: Implications for B-cell selection
AU - Lloyd, Katy A.
AU - Steen, Johanna
AU - Amara, Khaled
AU - Titcombe, Philip J.
AU - Israelsson, Lena
AU - Lundström, Susanna L.
AU - Zhou, Diana
AU - Zubarev, Roman A.
AU - Reed, Evan
AU - Piccoli, Luca
AU - Gabay, Cem
AU - Lanzavecchia, Antonio
AU - Baeten, Dominique
AU - Lundberg, Karin
AU - Mueller, Daniel L.
AU - Klareskog, Lars
AU - Malmström, Vivianne
AU - Grönwall, Caroline
PY - 2018
Y1 - 2018
N2 - Autoreactive B cells have a central role in the pathogenesis of rheumatoid arthritis (RA), and recent findings have proposed that anti-citrullinated protein autoantibodies (ACPA) may be directly pathogenic. Herein, we demonstrate the frequency of variable-region glycosylation in single-cell cloned mAbs. A total of 14 ACPA mAbs were evaluated for predicted N-linked glycosylation motifs in silico, and compared to 452 highly-mutated mAbs from RA patients and controls. Variable region N-linked motifs (N-X-S/T) were strikingly prevalent within ACPA (100%) compared to somatically hypermutated (SHM) RA bone marrow plasma cells (21%), and synovial plasma cells from seropositive (39%) and seronegative RA (7%). When normalized for SHM, ACPA still had significantly higher frequency of N-linked motifs compared to all studied mAbs including highly mutated HIV broadly-neutralizing and malaria-associated mAbs. The Fab glycans of ACPA-mAbs were highly sialylated, contributed to altered charge, but did not influence antigen binding. The analysis revealed evidence of unusual B-cell selection pressure and SHM-mediated decrease in surface charge and isoelectric point in ACPA. It is still unknown how these distinct features of anti-citrulline immunity may have an impact on pathogenesis. However, it is evident that they offer selective advantages for ACPA+ B cells, possibly through non-antigen driven mechanisms.
AB - Autoreactive B cells have a central role in the pathogenesis of rheumatoid arthritis (RA), and recent findings have proposed that anti-citrullinated protein autoantibodies (ACPA) may be directly pathogenic. Herein, we demonstrate the frequency of variable-region glycosylation in single-cell cloned mAbs. A total of 14 ACPA mAbs were evaluated for predicted N-linked glycosylation motifs in silico, and compared to 452 highly-mutated mAbs from RA patients and controls. Variable region N-linked motifs (N-X-S/T) were strikingly prevalent within ACPA (100%) compared to somatically hypermutated (SHM) RA bone marrow plasma cells (21%), and synovial plasma cells from seropositive (39%) and seronegative RA (7%). When normalized for SHM, ACPA still had significantly higher frequency of N-linked motifs compared to all studied mAbs including highly mutated HIV broadly-neutralizing and malaria-associated mAbs. The Fab glycans of ACPA-mAbs were highly sialylated, contributed to altered charge, but did not influence antigen binding. The analysis revealed evidence of unusual B-cell selection pressure and SHM-mediated decrease in surface charge and isoelectric point in ACPA. It is still unknown how these distinct features of anti-citrulline immunity may have an impact on pathogenesis. However, it is evident that they offer selective advantages for ACPA+ B cells, possibly through non-antigen driven mechanisms.
UR - https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85044848358&origin=inward
UR - https://www.ncbi.nlm.nih.gov/pubmed/29512823
U2 - https://doi.org/10.1002/eji.201747446
DO - https://doi.org/10.1002/eji.201747446
M3 - Article
C2 - 29512823
SN - 0014-2980
VL - 48
SP - 1030
EP - 1045
JO - European journal of immunology
JF - European journal of immunology
IS - 6
ER -