Systematic Investigation of the Role of Surfactant Composition and Choice of oil: Design of a Nanoemulsion-Based Adjuvant Inducing Concomitant Humoral and CD4+ T-Cell Responses
Induction of cell-mediated immune (CMI) responses is crucial for vaccine-mediated protection against difficult vaccine targets, e.g., Chlamydia trachomatis (Ct). Adjuvants are included in subunit vaccines to potentiate immune responses, but many marketed adjuvants stimulate predominantly humoral immune responses. Therefore, there is an unmet medical need for new adjuvants, which potentiate humoral and CMI responses. The purpose was to design an oil-in-water nanoemulsion adjuvant containing a synthetic CMI-inducing mycobacterial monomycoloyl glycerol (MMG) analogue to concomitantly induce humoral and CMI responses.
The influence of emulsion composition was analyzed using a systematic approach. Three factors were varied: i) saturation of the oil phase, ii) type and saturation of the applied surfactant mixture, and iii) surfactant mixture net charge.
The emulsions were colloidally stable with a droplet diameter of 150–250 nm, and the zeta-potential correlated closely with the net charge of the surfactant mixture. Only cationic emulsions containing the unsaturated surfactant mixture induced concomitant humoral and CMI responses upon immunization of mice with a Ct antigen, and the responses were enhanced when squalene was applied as the oil phase. In contrast, emulsions with neutral and net negative zeta-potentials did not induce CMI responses. The saturation degree of the oil phase did not influence the adjuvanticity.
Cationic, MMG analogue-containing nanoemulsions are potential adjuvants for vaccines against pathogens for which both humoral and CMI responses are needed.
Key Wordsadjuvant drug delivery emulsion immune response vaccine
Cationic adjuvant formulation
Cryo-transmission electron microscopy
Glucopyranosyl lipid A
Generally regarded as safe
High shear mixing
Major histocompatibility complex
Major outer membrane protein
Respiratory syncytial virus
Trivalent influenza vaccine
Intensity-weighted average hydrodynamic diameter
- 4.Agger EM, Rosenkrands I, Hansen J, Brahimi K, Vandahl BS, Aagaard C, et al. Cationic liposomes formulated with synthetic mycobacterial cord factor (CAF01): a versatile adjuvant for vaccines with different immunological requirements. PLoS One. 2008;3(9):e3116.CrossRefPubMedPubMedCentralGoogle Scholar
- 7.Nordly P, Korsholm KS, Pedersen EA, Khilji TS, Franzyk H, Jorgensen L, et al. Incorporation of a synthetic mycobacterial monomycoloyl glycerol analogue stabilizes dimethyldioctadecylammonium liposomes and potentiates their adjuvant effect in vivo. Eur J Pharm Biopharm. 2011;77(1):89–98.CrossRefPubMedGoogle Scholar
- 13.Olsen AW, Follmann F, Erneholm K, Rosenkrands I, Andersen P. Protection against Chlamydia trachomatis infection and upper genital tract pathological changes by vaccine-promoted neutralizing antibodies directed to the VD4 of the major outer membrane protein. J Infect Dis. 2015;212(6):978–89.CrossRefPubMedGoogle Scholar
- 25.Henriksen-Lacey M, Christensen D, Bramwell VW, Lindenstrøm T, Agger EM, Andersen P, et al. Liposomal cationic charge and antigen adsorption are important properties for the efficient deposition of antigen at the injection site and ability of the vaccine to induce a CMI response. J Control Release. 2010;145(2):102–8.CrossRefPubMedGoogle Scholar
- 26.Christensen D, Henriksen-Lacey M, Kamath AT, Lindenstrøm T, Korsholm KS, Christensen JP, et al. A cationic vaccine adjuvant based on a saturated quaternary ammonium lipid have different in vivo distribution kinetics and display a distinct CD4 T cell-inducing capacity compared to its unsaturated analog. J Control Release. 2012;160(3):468–76.CrossRefPubMedGoogle Scholar