title: Nano-Self-Assemblies Based on Synthetic Analogues of Mycobacterial Monomycoloyl Glycerol and DDA: Supramolecular Structure and Adjuvant Efficacy.
abstract: The mycobacterial cell-wall lipid monomycoloyl glycerol (MMG) is a potent immunostimulator, and cationic liposomes composed of a shorter synthetic analogue (MMG-1) and dimethyldioctadecylammonium (DDA) bromide represent a promising adjuvant that induces strong antigen-specific Th1 and Th17 responses. In the present study, we investigated the supramolecular structure and in vivo adjuvant activity of dispersions based on binary mixtures of DDA and an array of synthetic MMG-1 analogues (MMG-2/3/5/6) displaying longer (MMG-2) or shorter (MMG-3) alkyl chain lengths, or variations in stereochemistry of the polar headgroup (MMG-5) or of the hydrophobic moiety (MMG-6). Synchrotron small-angle X-ray scattering experiments and cryo transmission electron microscopy revealed that DDA:MMG-1/2/5/6 dispersions consisted of unilamellar and multilamellar vesicles (ULVs/MLVs), whereas a coexistence of both ULVs and hexosomes was observed for DDA:MMG-3, depending on the DDA:MMG molar ratio. The studies also showed that ULVs were formed, regardless of the structural characteristics of the neat MMG analogues in excess buffer [lamellar (MMG-1/2/5) or inverse hexagonal (MMG-3/6) phases]. Immunization of mice with a chlamydia antigen surface-adsorbed to DDA:MMG-1/3/6 dispersions revealed that all tested adjuvants were immunoactive and induced strong Th1 and Th17 responses with a potential for a central effector memory profile. The MMG-1 and MMG-6 analogues were equally immunoactive in vivo upon incorporation into DDA liposomes, despite the reported highly different immunostimulatory properties of the neat analogues in vitro, which were attributed to the different nanostructural characteristics. This clearly demonstrates that optimal formulation and delivery of MMG analogues to the immune system is of major importance and challenges the use of in vitro screening assays with nondispersed compounds to identify potential new vaccine adjuvants.
authors.affiliation: Department of Pharmacy, Faculty of Health and Medical Sciences, University of Copenhagen , Universitetsparken 2, DK-2100 Copenhagen, Denmark.
authors.forename: Birte
authors.initials: B
authors.lastname: Martin-Bertelsen
authors.affiliation: Department of Infectious Disease Immunology, Vaccine Adjuvant Research, Statens Serum Institut , Artillerivej 5, DK-2300 Copenhagen, Denmark.
authors.forename: Karen S
authors.initials: KS
authors.lastname: Korsholm
authors.affiliation: Department of Pharmacy, Faculty of Health and Medical Sciences, University of Copenhagen , Universitetsparken 2, DK-2100 Copenhagen, Denmark.
authors.forename: Carla B
authors.initials: CB
authors.lastname: Roces
authors.affiliation: Department of Pharmacy, Faculty of Health and Medical Sciences, University of Copenhagen , Universitetsparken 2, DK-2100 Copenhagen, Denmark.|Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen , Universitetsparken 2, DK-2100 Copenhagen, Denmark.
authors.forename: Maja H
authors.initials: MH
authors.lastname: Nielsen
authors.affiliation: Department of Infectious Disease Immunology, Vaccine Adjuvant Research, Statens Serum Institut , Artillerivej 5, DK-2300 Copenhagen, Denmark.
authors.forename: Dennis
authors.initials: D
authors.lastname: Christensen
authors.affiliation: Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen , Universitetsparken 2, DK-2100 Copenhagen, Denmark.
authors.forename: Henrik
authors.initials: H
authors.lastname: Franzyk
authors.affiliation: Department of Pharmacy, Faculty of Health and Medical Sciences, University of Copenhagen , Universitetsparken 2, DK-2100 Copenhagen, Denmark.
authors.forename: Anan
authors.initials: A
authors.lastname: Yaghmur
authors.affiliation: Department of Pharmacy, Faculty of Health and Medical Sciences, University of Copenhagen , Universitetsparken 2, DK-2100 Copenhagen, Denmark.
authors.forename: Camilla
authors.initials: C
authors.lastname: Foged
mesh_terms: D000276:Adjuvants, Immunologic / Q000138:chemical synthesis* / Q000737:chemistry*; D000818:Animals; D020285:Cryoelectron Microscopy; D005260:Female; D008081:Liposomes / Q000737:chemistry; D051379:Mice; D008810:Mice, Inbred C57BL; D046529:Microscopy, Electron, Transmission; D050178:Monoglycerides / Q000737:chemistry*; D049329:Nanostructures / Q000737:chemistry; D000644:Quaternary Ammonium Compounds / Q000737:chemistry*
chemical_list: D000276:Adjuvants, Immunologic; D008081:Liposomes; D050178:Monoglycerides; D000644:Quaternary Ammonium Compounds; C543328:monomycoloyl glycerol; C015831:dimethyldioctadecylammonium
keywords: adjuvant; dimethyldioctadecylammonium (DDA); monomycoloyl glycerol (MMG); nanostructure; self-assembly; vaccine