Published Online
on May 14, 2009

A more recent version of this article appeared on August 1, 2009

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Original Article

Proteomics, Metabolomics, and Immunomics on Microparticles Derived from Human Atherosclerotic Plaques

Manuel Mayr^1,6; David Grainger²; Ursula Mayr¹; Aurelie S. Leroyer³; Guy Leseche³; Anissa Sidibe¹; Olivier Herbin³; Xiaoke Yin¹; Aldrin Gomes⁴; Basseti Madhu⁵; John R. Griffiths⁵; Qingbo Xu¹; Alain Tedgui³ and Chantal M. Boulanger³

¹ King's College London, London, United Kingdom;
² Addenbrooke's Hospital, Cambridge, United Kingdom;
³ Université Paris–Descartes, Paris, France;
⁴ University of California, Davis, Davis, CA;
⁵ Cancer Research UK & Cambridge Research Institute, Cambridge, United Kingdom

http://www.vascular-proteomics.com

⁶ E-mail: manuel.mayr{at}kcl.ac.uk

Background—Microparticles (MPs) with procoagulant activity are present in human atherosclerosis, but no detailed information is available on their composition.

Methods and Results—To obtain insights into the role of MPs in atherogenesis, MP proteins were identified by tandem mass spectrometry, metabolite profiles were determined by high-resolution NMR spectroscopy and antibody reactivity was assessed against combinatorial antigen libraries. Plaque MPs expressed surface antigens consistent with their leukocyte origin, including major histocompatibility complex class I and II, and induced a dose-dependent stimulatory effect on T-cell proliferation. Notably, taurine, the most abundant free organic acid in human neutrophils, which scavenges myeloperoxidase-catalyzed free radicals, was highly enriched in plaque MPs. Moreover, fluorescent labelling of proteins on the MP surface suggested immunoglobulins to be trapped inside, which was confirmed by flow cytometry analysis on permeabilized and non-permeabilized plaque MPs. Co-labelling for CD14 and IgG established that over 90% of the IgG containing MPs were CD14 positive, indicating a macrophage origin. Screening against a combinatorial antigen library revealed that the immunologic profiles of antibodies in MPs were similar to those found in plaques, but differed profoundly from antibodies in plasma and unexpectedly, showed strong reactions with oligosaccharide antigens, in particular blood group antigen A.

Conclusions—This study provides the first evidence that immunoglobulins are present within MPs derived from plaque macrophages, that the portfolio of plaque antibodies is different from circulating antibodies in plasma and that anti-carbohydrate antibodies are retained in human atherosclerotic lesions.

Key Words: antigens • atherosclerosis • carotid arteries • plaque • proteins • proteomics