A modified adenine chemically coupled to allergenic molecule(s) as inducer of allergen-specific Th2 cells redirection

Background: As the new TLR/-ligand 8-hydroxyadenine SA-2 was found by our group torevert allergen specific TH2 responses both in vitro and in vivo, we studied a new compuond able to be coupled with allergenic molecules as a possible new adjuvant for possible application in allergen-specific immunotherapy. Methods: THE 8-oh-substituted adenine SA-26e chemically coupled with Dermatophagoides Pteronissinus extract (DP-conj) or purified natural Der p2 (nDer p2-Conj) was evaluated for induction of NF-kB in CD14+ cells, cytokine production in BDCA4+ and CD14+ cells, Th-skewing effects in allergen-specific human T cell lines, TLR-triggering in transfected HEK293 cell line. Results: Both DP-Conj and nDer-Conj induced innate cells to produce IFN-alfa and IL-12. As a consequence, the two conjugates reverted TH2-prone allergen T cell lines into IFN-gamma-producing cells (TH1/TH0 phenotype) as assessed by cytokine production in the supernatants, intracellular cytokine expression and TH-related transcription factor expression. DP-Conj and nDer-Conj induced nuclear translocation of p50 and trigger TLR7. Conclusions: 8-hydroxy-adenines represent new compounds inducing NF-kB translocation and exhibiting TH1-inducing activity in vitro. A system of chemical conjugation to relevant proteins as allergens has been set up with maintenance of modulatory effects of these complexes thus allowing the development of new vaccine strategies.