Eosinophil-Selective Binding and Proapoptotic Effect in Vitro of a Synthetic Siglec-8 Ligand, Polymeric 6′-Sulfated Sialyl Lewis X
- Division of Allergy and Clinical Immunology, Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, Maryland (S.A.H., B.S.B.); Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russia (N.V.B.); Department of Pharmacology and Molecular Sciences, The Johns Hopkins University School of Medicine, Baltimore, Maryland (R.L.S.); and Division of Cell Biology and Immunology, the Wellcome Trust Biocentre at Dundee, University of Dundee, United Kingdom (P.R.C.)
- Address correspondence to:
Dr. Bruce S. Bochner, Johns Hopkins Asthma and Allergy Center, 5501 Hopkins Bayview Circle, Room 2B.71, Baltimore, MD 21224-6821. E-mail: bbochner{at}jhmi.edu
Abstract
The lectin Siglec-8 (sialic acid-binding, immunoglobulin-like lectin), which is selectively expressed on eosinophil surfaces and regulates eosinophil survival, preferentially binds to the glycan 6′-sulfo-sialyl Lewis X (6′-sulfo-sLex). Antibody engagement of Siglec-8 on eosinophils causes their apoptosis, suggesting that engagement of Siglec-8 with its natural glycan ligands in vivo may control allergic inflammation. We report that a soluble synthetic polymer displaying 6′-sulfo-sLex glycan selectively binds to human eosinophils and human embryonic kidney 293 cells expressing Siglec-8. Binding was inhibited by anti-Siglec-8 antibody. In whole blood, eosinophils were the only leukocyte subtype to detectably bind polymeric 6′-sulfo-sLex. Interleukin-5-primed eosinophils underwent apoptosis when incubated with either anti-Siglec-8 monoclonal antibody or polymeric 6′-sulfo-sLex, although the glycan polymer was less effective. These data demonstrate that a soluble, multivalent glycan selectively binds to human eosinophils and induces their apoptosis in vitro and provide proof-of-concept that such a reagent could be used to selectively target eosinophils.
Footnotes
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This work was supported in part by the National Institutes of Health National Institute of Allergy and Infectious Diseases [Grants AI41472, AI72265]; the Human Immunology grant program of the Dana Foundation (to B.S.B); and the Russian Academy of Sciences Presidium Program entitled “Molecular and Cell Biology” (to N.V.B.).
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B.S.B. received support as a Cosner Scholar in Translational Research from Johns Hopkins University.
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Drs. Bochner and Schnaar are coauthors on existing and pending Siglec-8-related patents. If Siglec-8-related products are developed in the future, under a licensing agreement between GlaxoSmithKline and the Johns Hopkins University, Drs. Bochner and Schnaar may be entitled to a share of royalties received by the University on the potential sales of such products. The terms of this arrangement are being managed by the Johns Hopkins University in accordance with its conflict of interest policies.
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Article, publication date, and citation information can be found at http://jpet.aspetjournals.org.
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doi:10.1124/jpet.109.152439.
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ABBREVIATIONS: sLex, sialyl Lewis X; HEK, human embryonic kidney; MFI, mean fluorescence intensity; PAA, polyacrylamide.
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- Received February 17, 2009.
- Accepted May 18, 2009.
- The American Society for Pharmacology and Experimental Therapeutics
