Design-of-experiments based development and in vitro evaluation of a cationic lipid-based triple adjuvanted subunit pertussis vaccine

The use of a cationic lipid nanoparticle based triple adjuvant complex (L-TriAdj) was previously demonstrated to provide great utility in enhancing local intranasal immunity against pertussis. However, the role of lipid composition as a critical product parameter has not been fully elucidated. The aim of this study was to optimize the lipid composition of L-TriAdj using design-of-experiments methodology, and to define the role of lipid composition on the physicochemical properties and in vitro behavior (cellular viability, uptake and cytokine expression) of L-TriAdj pertussis vaccine formulations applied to antigen presenting cells. L-TriAdj formulations were prepared using a thin-film hydration and extrusion method, with admixing of the adjuvant components and antigens. In-vitro experiments were conducted using the MTT assay, confocal imaging and flow cytometry. The DoE approach was used to optimize L-TriAdj vaccine formulations to particle sizes less than 200 nm. Results indicated that increasing the alkyl chain length of phosphatidylcholine (PC) lipids was associated with significant changes in cellular viability, enhancement of cellular uptake and induction of IL-12 and IFN-γ. Varying the ratio between phosphoethanolamine and phosphatidylcholine lipids was associated with significant changes in cellular viability and uptake; however, no significant effects in dendritic cell maturation were noted.