title: Novel glycolipid TLR2 ligands of the type Pam2Cys-α-Gal: synthesis and biological properties.
abstract: A more complete understanding of the mechanism of action of TLR agonists has fueled the investigation of new synthetic immunoadjuvants. In this context, we designed and synthesized glycolipids of the type Pam(2)Cys-α-Galactose as novel immunoadjuvants. Their synthesis required modifying a hydrophobic tBoc-[2,3-bispalmitoyloxy-(2R)-propyl]-R-cysteinyl moiety, i.e. the minimal structure required for TLR2 agonist activity, by addition of a hydrophilic head, either an α-Galactosylpyranose or an α-Galactosylfuranose to gain respectively Pam(2)CGalp and Pam(2)CGalf. While preparing a carbohydrate building block, an unexpected stereoselectivity was observed during a halide ion-catalytic process on a protected galactofuranose: the alpha anomer was obtained with surprisingly high selectivity (α/β ratio>9) and with good isolated yield (51%). The TLR2 binding properties of Pam(2)CGalp and Pam(2)CGalf were then fully evaluated. Their efficiency in triggering the proliferation of BALB/c mouse splenocytes was also compared to that of Pam(2)CAG and Pam(3)CAG, two well-established ligands of TLRs. Moreover, the maturation state of murine dendritic cells previously incubated with either Pam(2)CGalp or Pam(2)CGalf was monitored by flow cytometry and compared to that induced by lipopolysaccharide. Pam(2)CGalp and Pam(2)CGalf were found to be equivalent TLR2 agonists, and induced splenocyte proliferation and DC maturation. With very similar activity, Pam(2)CGalp and Pam(2)CGalf were also 10-fold to 100-fold better than Pam(2)CAG and Pam(3)CAG at inducing B cell proliferation. This represents the first time a glucidic head has been added to the tBoc-[2,3-bispalmitoyloxy-(2R)-propyl]-R-cysteinyl moiety whilst maintaining the immunomodulating activity. This should greatly enrich the data available on Pam(2)C structure/activity relationships.
authors.affiliation: Equipe de Biovectorologie, Laboratoire de Conception et Application des Molécules Bioactives, UMR 7199 CNRS/Université de Strasbourg, Faculté de Pharmacie, 74 route du Rhin, 67401 Illkirch Cedex, France.
authors.forename: Jean-Sébastien
authors.initials: JS
authors.lastname: Thomann
authors.forename: Fanny
authors.initials: F
authors.lastname: Monneaux
authors.forename: Gaëlle
authors.initials: G
authors.lastname: Creusat
authors.forename: Maria Vittoria
authors.initials: MV
authors.lastname: Spanedda
authors.forename: Béatrice
authors.initials: B
authors.lastname: Heurtault
authors.forename: Chloé
authors.initials: C
authors.lastname: Habermacher
authors.forename: Francis
authors.initials: F
authors.lastname: Schuber
authors.forename: Line
authors.initials: L
authors.lastname: Bourel-Bonnet
authors.forename: Benoît
authors.initials: B
authors.lastname: Frisch
mesh_terms: D000276:Adjuvants, Immunologic / Q000138:chemical synthesis / Q000737:chemistry* / Q000378:metabolism* / Q000494:pharmacology; D000818:Animals; D002460:Cell Line; D060326:Chemistry Techniques, Synthetic; D005260:Female; D005690:Galactose / Q000737:chemistry*; D006017:Glycolipids / Q000138:chemical synthesis / Q000737:chemistry* / Q000378:metabolism* / Q000494:pharmacology; D006801:Humans; D008024:Ligands; D051379:Mice; D013329:Structure-Activity Relationship; D051195:Toll-Like Receptor 2 / Q000819:agonists / Q000378:metabolism*
chemical_list: D000276:Adjuvants, Immunologic; D006017:Glycolipids; D008024:Ligands; D051195:Toll-Like Receptor 2; D005690:Galactose