TY - JOUR
T1 - N-glycan mediated shielding of ADAMTS13 prevents binding of pathogenic autoantibodies in immune-mediated TTP
AU - Ercig, Bogac
AU - Gomes Graca, Nuno Alexandre
AU - Kangro, Kadri
AU - Arfman, Tom
AU - Wichapong, Kanin
AU - Hrdinova, Johana
AU - Kaijen, Paul
AU - van Alphen, Floris
AU - van den Biggelaar, Maartje
AU - Vanhoorelbeke, Karen
AU - Veyradier, Agnès
AU - Coppo, Paul
AU - Reutelingsperger, Chris
AU - Nicolaes, Gerry A F
AU - Männik, Andres
AU - Voorberg, Jan
N1 - Copyright © 2021 American Society of Hematology.
PY - 2021/5/13
Y1 - 2021/5/13
N2 - Immune-mediated thrombotic thrombocytopenic purpura (iTTP) is an autoimmune disorder caused by the development of autoantibodies targeting different domains of ADAMTS13. Profiling studies have shown that residues R568, F592, R660, Y661 and Y665 within exosite-3 of the spacer domain provide an immunodominant region of ADAMTS13 for pathogenic autoantibodies that develop in patients with iTTP. Modification of these 5 core residues with the goal of reducing auto-antibody binding revealed a significant trade-off between autoantibody resistance and proteolytic activity. Here, we employed structural bioinformatics to identify a larger epitope landscape on the ADAMTS13 spacer domain. Models of spacer-antibody complexes predicted that residues R568, L591, F592, K608, M609, R636, L637, R639, R660, Y661, Y665 and L668 contribute to an expanded epitope within the spacer domain. Based on bioinformatics-guided predictions we designed a panel of N-glycan insertions in this expanded epitope to reduce the binding of spacer domain autoantibodies. One N-glycan variant (NGLY3-ADAMTS13, containing a K608N substitution) showed strongly reduced reactivity with TTP patient sera (28%) as compared to WT-ADAMTS13 (100%). Insertion of an N-glycan at amino acid position 608 did not interfere with processing of VWF positioning the resulting NGLY3-ADAMTS13 variant as a potential novel therapeutic option for treatment of iTTP.
AB - Immune-mediated thrombotic thrombocytopenic purpura (iTTP) is an autoimmune disorder caused by the development of autoantibodies targeting different domains of ADAMTS13. Profiling studies have shown that residues R568, F592, R660, Y661 and Y665 within exosite-3 of the spacer domain provide an immunodominant region of ADAMTS13 for pathogenic autoantibodies that develop in patients with iTTP. Modification of these 5 core residues with the goal of reducing auto-antibody binding revealed a significant trade-off between autoantibody resistance and proteolytic activity. Here, we employed structural bioinformatics to identify a larger epitope landscape on the ADAMTS13 spacer domain. Models of spacer-antibody complexes predicted that residues R568, L591, F592, K608, M609, R636, L637, R639, R660, Y661, Y665 and L668 contribute to an expanded epitope within the spacer domain. Based on bioinformatics-guided predictions we designed a panel of N-glycan insertions in this expanded epitope to reduce the binding of spacer domain autoantibodies. One N-glycan variant (NGLY3-ADAMTS13, containing a K608N substitution) showed strongly reduced reactivity with TTP patient sera (28%) as compared to WT-ADAMTS13 (100%). Insertion of an N-glycan at amino acid position 608 did not interfere with processing of VWF positioning the resulting NGLY3-ADAMTS13 variant as a potential novel therapeutic option for treatment of iTTP.
KW - ANTIBODIES
KW - SPACER
U2 - 10.1182/blood.2020007972
DO - 10.1182/blood.2020007972
M3 - Article
C2 - 33544829
SN - 0006-4971
VL - 137
SP - 2694
EP - 2698
JO - Blood
JF - Blood
IS - 19
ER -