Specific sialoforms required for the immune suppressive activity of human soluble CD52
- Author(s)
- Shathili, AM; Bandala-Sanchez, E; John, A; Goddard-Borger, ED; Thaysen-Andersen, M; Everest-Dass, AV; Adams, TE; Harrison, LC; Packer, NH;
- Journal Title
- Frontiers in Immunology
- Publication Type
- Journal Article
- Abstract
- Human CD52 is a small glycopeptide (12 amino acid residues) with one N-linked glycosylation site at asparagine 3 (Asn3) and several potential O-glycosylation serine/threonine sites. Soluble CD52 is released from the surface of activated T cells and mediates immune suppression via its glycan moiety. In suppressing activated T cells, it first sequesters the pro-inflammatory high mobility group Box 1 (HMGB1) protein, which facilitates its binding to the inhibitory sialic acid-binding immunoglobulin-like lectin-10 (Siglec-10) receptor. We aimed to identify the features of CD52 glycan that underlie its bioactivity. Analysis of native CD52 purified from human spleen revealed extensive heterogeneity in N-glycosylation and multi-antennary sialylated N-glycans with abundant polyLacNAc extensions, together with mainly di-sialylated O-glycosylation type structures. Glycomic (porous graphitized carbon-ESI-MS/MS) and glycopeptide (C8-LC-ESI-MS) analysis of recombinant soluble human CD52-immunoglobulin Fc fusion proteins revealed that CD52 bioactivity was correlated with a high abundance of tetra-antennary alpha-2,3/6 sialylated N-glycans. Removal of alpha-2,3 sialylation abolished bioactivity, which was restored by re-sialylation with alpha-2,3 sialyltransferases. When glycoforms of CD52-Fc were fractionated by anion exchange MonoQ-GL chromatography, bioactive fractions displayed mainly tetra-antennary, alpha-2,3 sialylated N-glycan structures and a lower relative abundance of bisecting GlcNAc structures compared to non-bioactive fractions. In addition, O-glycan core type-2 di-sialylated structures at Ser12 were more abundant in bioactive CD52 fractions. Understanding the structural features of CD52 glycan required for its bioactivity will aid its development as an immunotherapeutic agent.
- Publisher
- Frontiers Media
- Research Division(s)
- Population Health And Immunity; Chemical Biology
- PubMed ID
- 31507595
- Publisher's Version
- https://doi.org/10.3389/fimmu.2019.01967
- Open Access at Publisher's Site
https://doi.org/10.3389/fimmu.2019.01967- NHMRC Grants
- NHMRC/1037321, NHMRC/1080887,
- Terms of Use/Rights Notice
- Refer to copyright notice on published article.
Creation Date: 2019-09-20 10:16:25
Last Modified: 2019-09-24 03:02:25