Nanostructure as system for optimizing efficacy of CpG-ODN.

SANCHEZ-VALLECILLO,MF; PALMA, S; ULLO, G; ALLEMANDI, D; MORÓN, G; PISTORESI, MC; MALETTO, B

Buenos Aires

Congreso; First French-Argentine Immunology Congress.; 2010

Sociedad Argentina de Inmunología

CpG-ODN has successfully used as vaccine adjuvant but unfortunately has a reduced bioavailability. In order to improve their bioavailability we have used CpG-ODN formulated in a nanostructure of 6-O- ascorbyl palmitate (Coa-ASC16), which has the ability to form supramolecular aggregate that are produced by phase cooling below a critical micellar temperature. Previously, we have observed that this strategy increased the bioavailability considering that improved the CpG-ODN adjuvant activity. However, we still ignore the mechanisms by which Coa-ASC16 works. Perhaps more than one factor could be synergistically contributing. Here, we tested whether Coa-ASC16 “per se” is able to stimulate immune system. Mice were i.p. injected with Coa-ASC16 or without Coa-ASC16 (control group). Coa-ASC16 induced a recruitment of neutrophils (Ly6Ghigh, F4/80-, CD11b+, Ly6C+) (23±8 vs control:0.06±0.09 % after two hours injection p<0.05) and inflammatory monocytes (Ly6Chigh, Ly6G-, F4/80-, CD11b+) (25±3 vs control:3±1 % after six hours injection p<0.05) into the peritoneal cavity. We also observed production of IL-6 (ng/ml, 0.8±0.4 vs control:0.07±0.02 after two hours injection p<0.05) in macrophages, neutrophils and inflammatory monocytes. These experiments were also carried out in TLR4-/- animals obtaining the same result. In addition, we evaluated the levels of LDH, ALT and AST enzymes released into the peritoneal lavage to assess cell damage/lysis. Coa-ASC16 induced an increase of levels of these enzymes two hours after injection: LDH (U/l) (7100±1600 vs control: 1400±780 p<0.001), AST (U/l) (230±74 vs control:37±12 p<0.001), ALT (U/l) (92±38 vs control:19±7 p<0.005). These observations suggest that one of the factors by Coa-ASC16 may enhance the effect of CpG-ODN is the recruiting of innate immune cells to the site of injection. Coa-ASC16 cause tissue damage at the site of injection and then could act as “endogenous danger signals” which may initiate a sterile inflammatory response.