Characterization of Flagellin-Functionalized Liposomes as a Vaccine Carrier and Adjuvant.

[摘要] Since the recognition that the adjuvant capacity of flagellin is better harnessed when both flagellin and the antigen are delivered to the same cell, there has been a need to exploit flagellin in ways that fulfill this constraint. We propose a liposomal delivery system functionalized with Salmonella typhimurium flagellin (fliC) as a way to meet this need. Our goal is to characterize the fliC-functionalized liposome as a vaccine adjuvant and evaluate its ability to target cells expressing Toll Like receptor 5 to enhance the vaccine potential of a liposome-encapsulated antigen. Proinflammatory cytokine secretion and preferential cell association were evaluated in murine alveolar macrophage cell line and bone marrow-derived macrophages in vitro. Caspase-1 activation and IL-1β secretion were used to determine inflammasome activation in studies employing LLO to gain cytosolic access.After a prime-boost immunization regimen, humoral and CD8+ T cell adjuvant effect of functionalized liposomes in vivo were determined by quantifying antigen-specific IgG1 and IgG2c and tetramer staining of antigen-specific CD8+ T cells. We report that fliC-functionalized liposomes are able to elicit the proinflammatory cytokine, IL-6, with comparable efficacy to soluble protein in a TLR5-mediated manner from an alveolar macrophage cell line but not from bone marrow-derived macrophages. FliC-functionalized liposomes also demonstrate the capacity to preferentially associate with flagellin-responsive cells, enhance MHC class I –restricted peptide presentation in vitro, and elicit IgG1 and CD8+ T cell response specific to liposome-encapsulated antigen. Using LLO-encapsulating flagellin-bearing liposomes, we demonstrate that fliC delivery to the cytosol enhances inflammasome activation and fliC-functionalized LLO liposomes are able to stimulate antigen-specific IgG1 in immunized mice. The physicochemical stability of the flagellin-functionalized liposome and the immune profile it elicits recommend fliC-functionalized liposomes as feasible for vaccine carrier and adjuvant function.

[发布机构] University of Michigan

[效力级别] Vaccine delivery

[关键词] TLR5;Vaccine delivery;Liposomes;Drug targeting;Flagellin;Adjuvant;Biomedical Engineering;Pharmacy and Pharmacology;Science (General);Health Sciences;Science;Pharmaceutical Sciences