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Coagulation & its Disorders
Mass spectrometry-assisted identification of ADAMTS13-derived peptides presented on HLA-DR and HLA-DQ
Johana Hrdinová,1* Fabian C. Verbij,1* Paul H.P. Kaijen,1 Robin B. Hartholt,1 Floris van Alphen,2 Neubury Lardy,3 Anja ten Brinke,4 Karen Vanhoorelbeke,5 Pooja J. Hindocha,6 Anne S. De Groot,6,7 Alexander B. Meijer,1,2,8
Jan Voorberg1,9 and Ivan Peyron1
1Department of Plasma Proteins, Sanquin Research and Landsteiner Laboratory, Academic Medical Center, University of Amsterdam, the Netherlands; 2Department of Research Facilities, Sanquin Research and Landsteiner Laboratory, Academic Medical Center, University of Amsterdam, the Netherlands; 3Department of Immunogenetics, Sanquin, Amsterdam, the Netherlands; 4Department of Immunopathology, Sanquin Research and Landsteiner Laboratory, Academic Medical Center, University of Amsterdam, the Netherlands; 5Laboratory for Thrombosis Research, IRF Life Sciences, KU Leuven Campus Kulak Kortrijk, Belgium; 6EpiVax Inc., Providence, RI, USA; 7Institute for Immunology and Informatics, University of Rhode Island, Providence, RI, USA; 8Pharmaceutics, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, the Netherlands and 9Department of Experimental Vascular Medicine, Academic Medical Center, Amsterdam,
ABSTRACT
Formation of microthrombi is a hallmark of acquired thrombotic thrombocytopenic purpura. These microthrombi originate from insufficient processing of ultra large von Willebrand factor multimers by ADAMTS13 due to the development of anti-ADAMTS13 autoanti- bodies. Several studies have identified the major histocompatibility com- plex class II alleles HLA-DRB1*11, HLA-DQB1*03 and HLA-DQB1*02:02 as risk factors for acquired thrombotic thrombocytopenic purpura devel- opment. Previous research in our department indicated that ADAMTS13 CUB2 domain-derived peptides FINVAPHAR and LIRDTHSLR are pre- sented on HLA-DRB1*11 and HLA-DRB1*03, respectively. Here, we describe the repertoire of ADAMTS13 peptides presented on HLA-DQ. In parallel, the repertoire of ADAMTS13-derived peptides presented on HLA-DR was monitored. Using HLA-DR- and HLA-DQ-specific antibod- ies, we purified HLA/peptide complexes from ADAMTS13-pulsed monocyte-derived dendritic cells. Using this approach, we identified ADAMTS13-derived peptides presented on HLA-DR for all 9 samples analyzed; ADAMTS13-derived peptides presented on HLA-DQ were identified in 4 out of 9 samples. We were able to confirm the presentation of the CUB2 domain-derived peptides FINVAPHAR and LIRDTHSLR on HLA-DR. In total, 12 different core-peptide sequences were identified on HLA-DR and 8 on HLA-DQ. For HLA-DR11, several potential new core- peptides were found; 4 novel core-peptides were exclusively identified on HLA-DQ. Furthermore, an in silico analysis was performed using the EpiMatrix and JanusMatrix tools to evaluate the eluted peptides, in the context of HLA-DR, for putative effector or regulatory T-cell responses at the population level. The results from this study provide a basis for the identification of immuno-dominant epitopes on ADAMTS13 involved in the onset of acquired thrombotic thrombocytopenic purpura.
Introduction
Thrombotic thrombocytopenic purpura (TTP) is a severe life-threatening disor- der caused by decreased levels of functional ADAMTS13 (a disintegrin and metalloproteinase with thrombospondin type 1 motifs, member 13). In healthy individuals, ADAMTS13 regulates the size of von Willebrand Factor (VWF) multi-
Ferrata Storti Foundation
Haematologica 2018 Volume 103(6):1083-1092
the Netherlands
*JH and FCV contributed equally.
Correspondence:
j.voorberg@sanquin.nl
Received: August 21, 2017. Accepted: March 14, 2018. Pre-published: March 22, 2018.
doi:10.3324/haematol.2017.179119
Check the online version for the most updated information on this article, online supplements, and information on authorship & disclosures: www.haematologica.org/content/103/6/1083
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