Cellular vaccines in listeriosis: role of the Listeria antigen GAPDH

Abstract

The use of live Listeria-based vaccines carries serious difficulties when administrated to immunocompromised individuals. However, cellular carriers have the advantage of inducing multivalent innate immunity as well as cell-mediated immune responses, constituting novel and secure vaccine strategies in listeriosis. Here, we compare the protective efficacy of dendritic cells (DCs) and macrophages and their safety. We examined the immune response of these vaccine vectors using two Listeria antigens, listeriolysin O (LLO) and glyceraldehyde-3-phosphate-dehydrogenase (GAPDH), and several epitopes such as the LLO peptides, LLO189−201 and LLO91−99 and the GAPDH peptide, GAPDH1−22. We discarded macrophages as safe vaccine vectors because they show anti-Listeria protection but also high cytotoxicity. DCs loaded with GAPDH1−22 peptide conferred higher protection and security against listeriosis than the widely explored LLO91−99 peptide. Anti-Listeria protection was related to the changes in DC maturation caused by these epitopes, with high production of interleukin-12 as well as significant levels of other Th1 cytokines such as monocyte chemotactic protein-1, tumor necrosis factor-α, and interferon-γ, and with the induction of GAPDH1−22-specific CD4+ and CD8+ immune responses. This is believed to be the first study to explore the use of a novel GAPDH antigen as a potential DC-based vaccine candidate for listeriosis, whose efficiency appears to highlight the relevance of vaccine designs containing multiple CD4+ and CD8+ epitopes.

A Novel Therapy for Melanoma Developed in Mice: Transformation of Melanoma into Dendritic Cells with Listeria monocytogenes

“…This mechanism of action resembles the efficiency of a recent dendritic-based vaccination against listeriosis that our group, as well as others [15, 26], reported using DC loaded with LLO 91–99 peptide and open up future dendritic-based vaccination protocols for melanoma using Listeria peptides.…”

“…1C) [16–18]. J-774 macrophages presented almost all MIIC markers except for low levels of cathepsin-D, while non-APC cells as MEF or CHO exclusively showed the MIIC marker Rab5a, indicating very low MIIC competency ( S1B Fig. ) [15, 18]. …”

“…We previously reported this characteristic DC phenotype and cytokine pattern on a dendritic-based vaccine for listeriosis that triggers a pro-inflammatory CD8 + T cell based immune response [15]. LM WT infection of other APC such as J-774 macrophages does not cause transformation into DC-like phenotypes ( S1 Fig., panel C ), either production of the pro-inflammatory cytokines above-mentioned [15, 17]. In brief, LM WT infection transformed melanoma into matured DC with competent APC functions and potential for tumour therapies.…”

“…Bone-marrow-derived dendritic cells (BMDC) were obtained from femurs of C57BL/6, Balb/c or CD-1 mice differentiated with 25 ng/ml granulocyte-macrophage colony-stimulating factor (GM-CSF) for 7 days as described [15]. Murine embryonic fibroblasts were cultured after thawing as previously described [16].…”

“…LLO 296–304 peptide (40 μM) was pre-incubated with PE-conjugated H-2K b :Ig (1 μM) in PBS, at 37°C for 16 h as previously described [15]. Splenocytes (2 × 10 7 cells/ml) were incubated with IFN-gamma and CD8 antibodies and the staining cocktail mix described above for 10 min at 4°C.…”