Novel imiquimod nanovesicles for topical vaccination

Abstract

Development of needle and pain free noninvasive immunization procedures is a top priority for public health agencies. In this work the topical adjuvant activity of the immunomodulator imiquimod (IMQ) carried by ultradeformable archaeosomes (UDA 2 ) (nanovesicles containing sn-2,3 ether linked phytanyl saturated archaeolipids) was surveyed and compared with that of ultradeformable liposomes lacking archaeolipids (UDL 2 ) and free IMQ, using the model antigen ovalbumin and a seasonal influenza vaccine in Balb/c mice. UDA 2 (250 ± 94 nm, -26 ± 4 mV Z potential) induced higher IMQ accumulation in human skin and higher production of TNF-α and IL-6 by macrophages and keratinocytes than free IMQ and UDL 2 . Mixed with ovalbumin, UDA 2 was more efficient at generating cellular response, as measured by an increase in serum IgG2a and INF-γ production by splenocytes, compared with free IMQ and UDL 2 . Moreover, mixed with a seasonal influenza vaccine UDA 2 produced same IgG titers and IgG2a/IgG1 isotypes ratio (≈1) than the subcutaneously administered influenza vaccine. Topical UDA 2 however, induced highest stimulation index and INF-γ levels by splenocytes. UDA 2 might be a promising adjuvant for topical immunization, since it produced cell-biased systemic response with ≈ 13-fold lower IMQ dose than the delivered as the commercial IMQ cream, Aldara.