Changes in the availability of vaccine components in draining lymph node are observed when a liquid crystal nanostructure is used as vaccine platform.

MARÍN, C; CHIODETTI, A; SANCHEZ-VALLECILLI, MF; RUIZ MORENO F; PALMA, S; MORÓN, G; ALLEMANDI, D; PISTORESI, MC; MALETTO, B

Mar del Plata

Congreso; Reunión Anual de la Sociedad Argentina de Inmunología; 2018

Sociedad Argentina de Inmunología

Commonly subunit-based vaccine requires the addition of an adjuvant. To overcome this challenge, new adjuvant strategies are being developed worldwide in experimental models or in human clinical trials. In this context, we formulated a TLR-9 agonist, CpG-ODN and a model antigen, OVA, with a nanostructure (Coa-ASC16) formed by self-assembly of 6-O-ascorbyl palmitate (OCC). This nanoformulation elicited superior adaptive immune responses than soluble formulation of OVA/CpG-ODN (OC). In addition, Coa-ASC16 creates a depot of antigen and CpG-ODN at the injection site. However, details about in vivo mechanisms that dictate the priming of vaccine-induced immunity are lacking. Here, we investigate the early events in the proximal-draining lymph nodes (LN) of the vaccine injection site. Mice were subcutaneously immunized with formulations containing fluorescent-dye labeled OVA and CpG-ODN. Then, the availability of both molecules contained in the whole LN was measured with Odyssey® CLx at several time points post-immunization (p.i.). In addition, we determined, by flow cytometry, the uptake of both molecules from LN by dendritic cells (DC). OVA signal was OC>OCC (p<0.001) and OCC>OC (p<0.0001) at 20 min and 24h p.i. respectively; CpG-ODN signal was OC>OCC (p<0.0001) and OCC>OC (p<0.0001) at 20 min and 24h p.i. respectively. 72 hs after immunization, we analyzed single cell suspension of LN and observed that Coa-ASC16 impacts on antigen uptake, mice immunized with OCC showed higher numbers of OVA+CD11c+DC, CpG-ODN+CD11c+DC and OVA+CpG-ODN+CD11c+DC compared with those mice immunized with OC (p<0.001). Conclusion: The nanoformulation of vaccine modifies the kinetics of antigen and immunostimulant availability in the LN and improves co-uptake of both molecules by DCs despite the fact that our system does not chemically link OVA to CpG-ODN. Understanding of the impact of vaccine formulation on early response might have a significant impact for rational vaccine design.