title: Listeriolysin O-liposome-mediated cytosolic delivery of macromolecule antigen in vivo: enhancement of antigen-specific cytotoxic T lymphocyte frequency, activity, and tumor protection.
abstract: Cytotoxic T lymphocytes (CTLs) are primed by peptide antigens that are endogenously processed in the cytosol and presented in the context of major histocompatibility complex I (MHC I) molecules of antigen-presenting cells (APCs). Exogenous soluble protein antigens do not gain efficient entry into the cytosol of APCs, and therefore requires a special cytosolic delivery method. We have developed such a delivery strategy adopting the well-elucidated cytosol-invading listerial endosomal escape mechanism, and report here an efficient delivery of exogenous whole protein antigen into the cytosol in a mouse model. Co-encapsulation of listeriolysin O (LLO) inside liposome (LLO-liposome) was required for delivery of ovalbumin (OVA) into the cytosol of APCs in primary cultures. LLO-liposome-mediated OVA immunization in mice engendered significantly higher OVA-specific CTL activity and increased antigenic peptide-specific CTL precursor (CTLp) frequency as compared to non-LLO-liposome or soluble OVA immunizations. Interferon-gamma (IFN-gamma) production upon specific stimulation by MHC I-restricted peptide was also significantly stronger by the inclusion of LLO in the liposomes. Rerouting of antigen into the cytosol by LLO-liposomes, however, did not reduce the extent of anti-OVA antibody responses. Moreover, LLO-liposome-antigen vaccination was robust in conferring protection to mice from lethal challenges with antigen-expressing tumor cells. Our study demonstrates a novel delivery system for efficient introduction of exogenous protein into the cytosol in vivo, priming cellular immune responses, which are protective in nature.
authors: Department of Pharmaceutical Sciences, College of Pharmacy, University of Michigan, 428 Church Street, Ann Arbor 48109-1065, USA.
authors: Manas
authors: M
authors: Mandal
authors: Kyung-Dall
authors: KD
authors: Lee
mesh_terms: D000818:Animals; D000938:Antigen-Presenting Cells / Q000276:immunology; D001427:Bacterial Toxins; D019496:Cancer Vaccines / Q000008:administration & dosage; D002478:Cells, Cultured; D003600:Cytosol / Q000276:immunology; D016503:Drug Delivery Systems; D004527:Egg Proteins / Q000008:administration & dosage / Q000276:immunology / Q000494:pharmacology; D006360:Heat-Shock Proteins / Q000008:administration & dosage*; D006460:Hemolysin Proteins; D007114:Immunization; D007371:Interferon-gamma / Q000378:metabolism; D007376:Interleukin-2 / Q000378:metabolism; D008081:Liposomes; D008264:Macrophages / Q000276:immunology; D051379:Mice; D008810:Mice, Inbred C57BL; D023421:Models, Animal; D010047:Ovalbumin / Q000008:administration & dosage / Q000276:immunology / Q000494:pharmacology; D010446:Peptide Fragments; D011994:Recombinant Proteins / Q000008:administration & dosage; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology* / Q000378:metabolism
chemical_list: D001427:Bacterial Toxins; D019496:Cancer Vaccines; D004527:Egg Proteins; D006360:Heat-Shock Proteins; D006460:Hemolysin Proteins; D007376:Interleukin-2; D008081:Liposomes; C110366:OVA-8; D010446:Peptide Fragments; D011994:Recombinant Proteins; D007371:Interferon-gamma; D010047:Ovalbumin; C038705:hlyA protein, Listeria monocytogenes