TY - JOUR
T1 - Affinity maturation shapes the function of agonistic antibodies to peptidylarginine deiminase type 4 in rheumatoid arthritis
AU - Shi, Jing
AU - Darrah, Erika
AU - Sims, Gary P.
AU - Mustelin, Tomas
AU - Sampson, Kevon
AU - Konig, Maximilian F.
AU - Bingham, Clifton O.
AU - Rosen, Antony
AU - Andrade, Felipe
N1 - Publisher Copyright:
© 2018 BMJ Publishing Group. All rights reserved.
PY - 2018/1
Y1 - 2018/1
N2 - Objectives T he citrullinating enzyme peptidylarginine deiminase type 4 (PAD4) is the target of a polyclonal group of autoantibodies in patients with rheumatoid arthritis (RA). A subgroup of such antibodies, initially identified by cross-reactivity with peptidylarginine deiminase type 3 (PAD3), is strongly associated with progression of radiographic joint damage and interstitial lung disease and has the unique ability to activate PAD4. The features of these antibodies in terms of their T celldependent origin, genetic characteristics and effect of individual antibody specificities on PAD4 function remain to be defined. Methods We used PAD4 tagged with the monomeric fluorescent protein mWasabi to isolate PAD4-specific memory B cells from anti-PAD4 positive patients with RA and applied single cell cloning technologies to obtain monoclonal antibodies. Results Among 44 single B cells, we cloned five antibodies with PAD4-Activating properties. Sequence analysis, germline reversion experiments and antigen specificity assays suggested that autoantibodies to PAD4 are not polyreactive and arise from PAD4-reactive precursors. Somatic mutations increase the agonistic activity of these antibodies at low calcium concentrations by facilitating their interaction with structural epitopes that modulate calcium-binding site 5 in PAD4. Conclusions P AD4-Activating antibodies directly amplify a key process in disease pathogenesis, making them unique among other autoantibodies in RA. Understanding the molecular basis for their functionality may inform the design of future PAD4 inhibitors.
AB - Objectives T he citrullinating enzyme peptidylarginine deiminase type 4 (PAD4) is the target of a polyclonal group of autoantibodies in patients with rheumatoid arthritis (RA). A subgroup of such antibodies, initially identified by cross-reactivity with peptidylarginine deiminase type 3 (PAD3), is strongly associated with progression of radiographic joint damage and interstitial lung disease and has the unique ability to activate PAD4. The features of these antibodies in terms of their T celldependent origin, genetic characteristics and effect of individual antibody specificities on PAD4 function remain to be defined. Methods We used PAD4 tagged with the monomeric fluorescent protein mWasabi to isolate PAD4-specific memory B cells from anti-PAD4 positive patients with RA and applied single cell cloning technologies to obtain monoclonal antibodies. Results Among 44 single B cells, we cloned five antibodies with PAD4-Activating properties. Sequence analysis, germline reversion experiments and antigen specificity assays suggested that autoantibodies to PAD4 are not polyreactive and arise from PAD4-reactive precursors. Somatic mutations increase the agonistic activity of these antibodies at low calcium concentrations by facilitating their interaction with structural epitopes that modulate calcium-binding site 5 in PAD4. Conclusions P AD4-Activating antibodies directly amplify a key process in disease pathogenesis, making them unique among other autoantibodies in RA. Understanding the molecular basis for their functionality may inform the design of future PAD4 inhibitors.
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U2 - 10.1136/annrheumdis-2017-211489
DO - 10.1136/annrheumdis-2017-211489
M3 - Article
C2 - 29070531
AN - SCOPUS:85038248681
SN - 0003-4967
VL - 77
SP - 141
EP - 148
JO - Annals of the rheumatic diseases
JF - Annals of the rheumatic diseases
IS - 1
ER -