A novel nDer p2-conjugated TLR7 down-modulates Th2-associated lung inflammation by using a therapeutical protocol

Background:Modified adenine (MA) binding TLR7 represent a new group of adjuvants for immunotherapy. We investigated the in vitro and in vivo effects of a synthetic MA [4-(6-amino-9-benzil-8-idrossi-9H-purin-2-ilsulfanil) butirrico 2,5-diossopirrolidin-1-il estere] called SA26E, chemically conjugated to purified allergen (nDer p2). In particular we analyzed the modulation of Th2-mediated immune response in a murine model of lung inflammation through a therapeutical protocol. Methods: C57Bl/6 mice were intraperitoneal (i.p.) immunised with nDer p2 at d0 and d7. At d14 mice were intratracheally challenged with nDer p2, while at d21 and d28 mice were i.p. treated with an administration of nDer p2-conjugate or nDer p2 alone as control. At d49 and d53 mice were again challenged with nDer p2 and then sacrified at d56 for the analysis. Results: SA26E stably conjugated to allergen, maintained the ability to trigger HEK293 cell line transfected with murine TLR7. Moreover, it downregulated eosinophils in bronchoalveolar lavage of mice treated with nDer p2-SA26E conjugated but not with nDer p2 alone. This effect was associated with a shift in the antibody profile from a type 2- (IgE and IgG1) to a type 1-associated (IgG2a) humoral response. A reduction of IL-13 and a parallel increase of IFN- c was observed in the supernatants of lung mononuclear cells in vitro stimulated with antigen. A concomitant significant increase of IL-10 levels was also found in the supernatants of nDer p2-stimulated cells of spleen and draining lymph nodes. Conclusion: These data suggest that the use of nDer p2-SA26E conjugated regulates and redirects the immune response in a therapeutical fashion and may constitute an useful approach for immunotherapy of allergic diseases.