Effect of Glycolipid Incorporation on Liposome Uptake by Antigen-Presenting Cells.

[摘要] Robust cell-mediated immune responses are considered vital for successful vaccination against intracellular pathogens and cancer. Enhancing antigen uptake by dendritic cells (DCs) is a proposed way to stimulate cell-mediated immune responses when using typically low immunogenic protein antigens. Formulating antigen into a nanoparticle carrier can increase antigen uptake by two major antigen-presenting cells (APCs), DCs and macrophages. However, macrophage uptake is generally accepted as the main route of nanoparticle clearance due to macrophages’ high phagocytic capability. To skew the antigen uptake by DC, previous approaches have relied on attaching complex targeting moieties to antigen itself or onto nanoparticle antigen carriers such as liposomes. We hypothesized that by retarding high macrophage uptake of liposomes, we could facilitate enhanced uptake of liposomes by DCs. Simple liposome formulations containing phosphatidylinositol (PI) or monosialotetrahexosylganglioside (GM1) are well documented to deter rapid uptake by macrophages. In vitro uptake studies showed that incorporating 10mol% PI promoted uptake by DCs, while having minimal effect on uptake by macrophages. This trend was not observed with 10mol% GM1 incorporation. In vivo uptake studies upon subcutaneous injection confirmed PI-liposomes are indeed internalized more by DCs than GM1-liposomes, however, this result was also observed in macrophages. These liposomal formulations are of interest as vaccine carriers to stimulate enhanced cell-mediated immune responses and the generation of CD8+ T cells via enhanced uptake by DCs.Extending on our previous work using liposomes co-encapsulating the model antigen (OVA) and a hemolysin, listeriolysin-O (LLO), we show, herein, that PI- and GM1-liposomes encapsulating OVA and LLO can deliver OVA to the cytosol of DCs and macrophages in cell culture, resulting in efficient antigen presentation to CD8+ T cells. Mice immunized with PI-liposomes or GM1-liposomes co-encapsulating OVA and LLO generated similar CD8+ T cell-mediated immune responses as determined by MHC I tetramer staining and IFN−gamma ELISPOT analysis. Vaccination with either liposome formulation resulted in enhanced antigen-specific serum IgG2a titers indicative of better Th1 helper T cell activation. Both PI-liposomes and GM1-liposomes represent simple, inexpensive vaccine carriers for effectively stimulating cell-mediated immune responses utilizing subunit protein antigens.

[发布机构] University of Michigan

[效力级别] liposome

[关键词] vaccine delivery;liposome;Pharmacy and Pharmacology;Health Sciences;Science;Pharmaceutical Sciences