title: Influence of trehalose 6,6'-diester (TDX) chain length on the physicochemical and immunopotentiating properties of DDA/TDX liposomes.
abstract: Linking physicochemical characterization to functional properties is crucial for defining critical quality attributes during development of subunit vaccines toward optimal safety and efficacy profiles. We investigated how the trehalose 6,6'-diester (TDX) chain length influenced the physicochemical and immunopotentiating properties of the clinically tested liposomal adjuvant composed of dimethyldioctadecylammonium (DDA) bromide and analogues of trehalose-6,6'-dibehenate (TDB). TDB analogues with symmetrically shortened acyl chains [denoted X: arachidate (A), stearate (S), palmitate (P), myristate (Myr) and laurate (L)] were incorporated into DDA liposomes and characterized with respect to size, polydispersity index, charge, thermotropic phase behavior and lipid-lipid interactions. Incorporation of 11 mol% TDX into DDA liposomes significantly decreased the polydispersity index when TDA, TDS, TDP and TDMyr were incorporated, whereas both the initial size and the charge of the liposomes were unaffected. The long-term colloidal stability was only decreased when including TDL in DDA liposomes. The fatty acid length of TDX affected the phase transition of the liposomes, and for the DDA/TDP and DDA/TDS liposomes a homogeneous distribution of the lipids in the bilayer was indicated. The membrane packing was studied further by using the Langmuir monolayer technique. Incorporation of TDS improved the packing of the lipid monolayer, as compared to the other analogues, suggesting the most favorable stability. Finally, immunization of mice with the recombinant tuberculosis fusion antigen Ag85B-ESAT-6-Rv2660c (H56) and the physicochemically most optimal formulations (DDA/TDB, DDA/TDS and DDA/TDP) induced comparable T-cell responses. In conclusion, of the investigated TDB analogues, incorporation of 11 mol% TDS or TDP into DDA liposomes resulted in an adjuvant system with the most favorable physicochemical properties and an immunological profile comparable to that of DDA/TDB.
authors.affiliation: Department of Pharmacy, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark; Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark; Department of Infectious Disease Immunology, Vaccine Adjuvant Research, Statens Serum Institut, Copenhagen, Denmark. Electronic address: rie.kallerup@sund.ku.dk.
authors.forename: Rie Selchau
authors.initials: RS
authors.lastname: Kallerup
authors.affiliation: Department of Pharmacy, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark; Department of Infectious Disease Immunology, Vaccine Adjuvant Research, Statens Serum Institut, Copenhagen, Denmark.
authors.forename: Cecilie Maria
authors.initials: CM
authors.lastname: Madsen
authors.affiliation: Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Mikkel Lohmann
authors.initials: ML
authors.lastname: Schiøth
authors.affiliation: Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 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, Copenhagen, Denmark.
authors.forename: Fabrice
authors.initials: F
authors.lastname: Rose
authors.affiliation: Department of Infectious Disease Immunology, Vaccine Adjuvant Research, Statens Serum Institut, Copenhagen, Denmark.
authors.forename: Dennis
authors.initials: D
authors.lastname: Christensen
authors.affiliation: Department of Infectious Disease Immunology, Vaccine Adjuvant Research, Statens Serum Institut, Copenhagen, Denmark.
authors.forename: Karen Smith
authors.initials: KS
authors.lastname: Korsholm
authors.affiliation: Department of Pharmacy, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark. Electronic address: camilla.foged@sund.ku.dk.
authors.forename: Camilla
authors.initials: C
authors.lastname: Foged
mesh_terms: D000276:Adjuvants, Immunologic / Q000737:chemistry / Q000494:pharmacology; D000818:Animals; D002626:Chemistry, Pharmaceutical / Q000379:methods; D005227:Fatty Acids / Q000737:chemistry / Q000276:immunology; D005260:Female; D007114:Immunization / Q000379:methods; D008081:Liposomes / Q000737:chemistry* / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D044367:Phase Transition; D000644:Quaternary Ammonium Compounds / Q000737:chemistry* / Q000276:immunology*; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000494:pharmacology; D013601:T-Lymphocytes / Q000187:drug effects / Q000276:immunology; D014199:Trehalose / Q000737:chemistry* / Q000276:immunology*
chemical_list: D000276:Adjuvants, Immunologic; C557979:Ag85B-ESAT-6 fusion antigen; D005227:Fatty Acids; D008081:Liposomes; D000644:Quaternary Ammonium Compounds; D011993:Recombinant Fusion Proteins; C015831:dimethyldioctadecylammonium; D014199:Trehalose
keywords: Adjuvant; Dimethyldioctadecylammonium; Liposome; Nanomedicine; Protein antigen; Trehalose-6,6′-dibehenate; Vaccine delivery