ADJUVANTICITY OF A NOVEL NANOSTRUCTURE FROM ASCORBYL PALMITATE REQUIRES THE ADAPTOR PROTEIN MYD88.

FERNANDA SÁNCHEZ-VALLECILLO; ANA CHIODETTI; GABRIELA ULLIO; SANTIAGO PALMA; DANIEL ALLEMANDI; GABRIEL MORÓN; MARÍA C PISTORESI- PALENCIA.; BELKYS A. MALETTO

Los Cocos

Congreso; LXI Reunión Anual de la Sociedad Argentina de Inmunología; 2013

Sociedad Argentina de Inmunología

CpG-ODN has successfully been used as adjuvant but unfortunately has a limited bioavailability; in order to improve it we formulated CpG-ODN in a nanostructure from 6-O-ascorbyl palmitate (Coa-ASC16). We previously showed that this strategy improves the adjuvant activity of CpG-ODN and that Coa-ASC16 promotes an inflammatory response at the injection site and also, it has adjuvant activity per se. In order to decipher the mechanism involved, we assessed the contribution of the adaptor protein MyD88 to the adjuvant activity of Coa-ASC16. MyD88-/- or WT mice received three immunizations (day 0, 7 and 15) with OVA (60μg/mice/dose) or OVA/Coa-ASC16. OVA-specific IgG1 (2.5±0.4 vs. 4.6±0.1), IgG2a (0.2±0.2 vs. 1.6±0.2) and IFN-γ (pg/ml: not detected vs. 931±223) were reduced in OVA/Coa-ASC16MyD88-/- mice compared with WT controls (p<0.01). Mice immunized with OVA alone were not reactive to antigen. To better understand the role of MyD88 in Coa-ASC16 adjuvanticity, we compared the innate immune response by Coa-ASC16 i.p. injection in WT, MyD88-/-, TLR4-/- and TLR2-/- mice. We found that proinflammatory cytokines and cellular recruitment in the peritoneum, 6h after injection, were significantly diminished in MyD88-/- mice compared with WT controls (pg/ml, IL-6: 117±33 vs 423±191, IL-12: 75±15 vs 130±19, IL-1β: 75±14 vs 174±32 (p<0.05); neutrophils: (1.0±0.3)x105 vs (24±5)x105, Ly6Chighmonocytes: (2±0,8)x105 vs (27±8)x105 (p<0.01)). TLR4-/- and TLR2-/- mice developed a similar response to WT mice. Our data show a connection between inflammatory environment induced by Coa-AC16 and its adjuvant effect. They also indicate a critical role for MyD88 in the adjuvant effect of Coa-ASC16; this may be linked to the biophysical properties of Coa-ASC16. A better understanding of the mechanism of initiating of innate immunity and its impact on downstream adaptive immune response has important implications for the rational use of a novel vaccine adjuvant.