title: Synthesis of a new nanomolar saccharide inhibitor of lymphocyte adhesion: different polylactosamine backbones present multiple sialyl Lewis x determinants to L-selectin in high-affinity mode.
abstract: Lymphocyte infiltration is a hallmark of acute rejections in solid organ transplants, such as cardiac allograft. We have previously shown that lymphocyte extravasation to cardiac grafts undergoing rejection is largely due to interactions between lymphocyte L-selectin and its sialyl Lewis x (sLex) decorated ligands. Our previous work demonstrated further that an enzymatically synthetized tetravalent sLex glycan of a branched polylactosamine backbone is a highly efficient inhibitor of L-selectin-dependent lymphocyte adhesion to graft endothelium. To improve the availability of multivalent sLex glycans for anti-inflammatory indications, we now report enzymatic synthesis of another tetravalent sLex glycan that can be potentially produced on a large scale, and show that even the new saccharide is a nanomolar inhibitor of L-selectin-dependent lymphocyte adhesion. The novel antagonist is sLex beta 1-3' (sLex beta 1-6') LacNAc beta 1-3' (sLex beta 1-6') LacNAc beta 1-3' (sLex beta 1-6') LacNAc (8) (where LacNAc is the disaccharide Gal beta 1-4GlcNac and sLex is the tetrasaccharide Neu5Ac alpha 2-3Gal beta 1-4 (Fuc alpha 1-3) GlcNAc). Its five-step synthesis was started from the octameric polylactosamine LacNAc beta 1-3' (GlcNAc beta 1-6') LacNAc beta 1-3' (GlcNAc beta 1-6') LacNAc (3), which in turn is accessible in one step from the hexasaccharide LacNAc beta 1-3'LacNAc beta 1-3'LacNAc. Importantly, the hexasaccharide primer has been synthesized chemically (Alais and Veyrieres, Tetrahedron Lett., 24, 5223, 1983). Hence, our data outline a route to glycan 8, consisting of a combination of chemical and enzymatic methods of oligosaccharide synthesis. In addition, our data show that polylactosamine backbones are able to present multiple sialyl Lewis x determinants to L-selectin in high-affinity mode, without a requirement for uniqueness in the backbone structure.
authors.affiliation: Institute of Biotechnology, University of Helsinki, Finland.
authors.forename: O
authors.initials: O
authors.lastname: Renkonen
authors.forename: S
authors.initials: S
authors.lastname: Toppila
authors.forename: L
authors.initials: L
authors.lastname: Penttilä
authors.forename: H
authors.initials: H
authors.lastname: Salminen
authors.forename: J
authors.initials: J
authors.lastname: Helin
authors.forename: H
authors.initials: H
authors.lastname: Maaheimo
authors.forename: C E
authors.initials: CE
authors.lastname: Costello
authors.forename: J P
authors.initials: JP
authors.lastname: Turunen
authors.forename: R
authors.initials: R
authors.lastname: Renkonen
mesh_terms: D000606:Amino Sugars / Q000737:chemistry*; D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D002448:Cell Adhesion / Q000187:drug effects*; D004727:Endothelium / Q000166:cytology; D006084:Graft Rejection / Q000517:prevention & control; D016027:Heart Transplantation; D019041:L-Selectin / Q000494:pharmacology*; D008214:Lymphocytes / Q000187:drug effects / Q000502:physiology*; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D009844:Oligosaccharides / Q000737:chemistry*; D011134:Polysaccharides / Q000138:chemical synthesis* / Q000737:chemistry* / Q000494:pharmacology; D000080506:Sialyl Lewis X Antigen
chemical_list: D000606:Amino Sugars; D009844:Oligosaccharides; D011134:Polysaccharides; D000080506:Sialyl Lewis X Antigen; C107226:tetravalent sialyl Lewis x saccharide; C066929:polylactosamine; D019041:L-Selectin