Synthetic Glycolipids as Molecular Vaccine Adjuvants: Mechanism of Action in Human Cells and In Vivo Activity

• Published in: Journal of medicinal chemistry 2021-08, Vol.64 (16), p.12261-12272
• Main Authors: Facchini, Fabio A, Minotti, Alberto, Luraghi, Andrea, Romerio, Alessio, Gotri, Nicole, Matamoros-Recio, Alejandra, Iannucci, Andrea, Palmer, Charys, Wang, Guanbo, Ingram, Rebecca, Martin-Santamaria, Sonsoles, Pirianov, Grisha, De Andrea, Marco, Valvano, Miguel A, Peri, Francesco
• Format: Article
• Language: English
• Subjects: Adaptor Proteins, Vesicular Transport - metabolism; Adjuvants, Immunologic - chemical synthesis; Adjuvants, Immunologic - metabolism; Adjuvants, Immunologic - pharmacology; Adjuvants, Immunologic - toxicity; Animals; Female; Glucosamine - chemical synthesis; Glucosamine - metabolism; Glucosamine - pharmacology; Glucosamine - toxicity; Glycolipids - chemical synthesis; Glycolipids - metabolism; Glycolipids - pharmacology; Glycolipids - toxicity; Humans; Inflammasomes - metabolism; Interleukin-1 - metabolism; Macrophages - drug effects; Mice; Mice, Inbred C57BL; Myeloid Differentiation Factor 88 - metabolism; NLR Family, Pyrin Domain-Containing 3 Protein - metabolism; Signal Transduction - drug effects; Toll-Like Receptor 4 - antagonists & inhibitors; Toll-Like Receptor 4 - metabolism
• ISSN: 0022-2623; 1520-4804
• DOI: 10.1021/acs.jmedchem.1c00896

Modern adjuvants for vaccine formulations are immunostimulating agents whose action is based on the activation of pattern recognition receptors (PRRs) by well-defined ligands to boost innate and adaptive immune responses. Monophosphoryl lipid A (MPLA), a detoxified analogue of lipid A, is a clinically approved adjuvant that stimulates toll-like receptor 4 (TLR4). The synthesis of MPLA poses manufacturing and quality assessment challenges. Bridging this gap, we report here the development and preclinical testing of chemically simplified TLR4 agonists that could sustainably be produced in high purity and on a large scale. Underpinned by computational and biological experiments, we show that synthetic monosaccharide-based molecules (FP compounds) bind to the TLR4/MD-2 dimer with submicromolar affinities stabilizing the active receptor conformation. This results in the activation of MyD88- and TRIF-dependent TLR4 signaling and the NLRP3 inflammasome. FP compounds lack in vivo toxicity and exhibit adjuvant activity by stimulating antibody responses with a potency comparable to MPLA.