krn-7000 and Malaria

A CD1d-binding, invariant (i) natural killer T (NKT)-cell stimulatory glycolipid, α-Galactosylceramide (αGalCer), has been shown to act as an adjuvant. We previously identified a fluorinated phenyl ring-modified αGalCer analog, 7DW8-5, displaying a higher binding affinity for CD1d molecule and more potent adjuvant activity than αGalCer. In the present study, 7DW8-5 co-administered intramuscularly (i.m.) with a recombinant adenovirus expressing a Plasmodium yoelii circumsporozoite protein (PyCSP), AdPyCS, has led to a co-localization of 7DW8-5 and a PyCSP in draining lymph nodes (dLNs), particularly in dendritic cells (DCs). This occurrence initiates a cascade of events, such as the recruitment of DCs to dLNs and their activation and maturation, and the enhancement of the ability of DCs to prime CD8+ T cells induced by AdPyCS and ultimately leading to a potent adjuvant effect and protection against malaria.

Topics: Adenoviridae; Adjuvants, Immunologic; Animals; Antigens, CD1d; Antigens, Protozoan; CD8-Positive T-Lymphocytes; Dendritic Cells; Galactosylceramides; Immunogenicity, Vaccine; Injections, Intramuscular; Interferon-gamma; Killer Cells, Natural; Lymphocyte Activation; Malaria; Malaria Vaccines; Mice; Natural Killer T-Cells; Plasmodium yoelii; Vaccines, Synthetic

A CD1d-binding glycolipid, α-Galactosylceramide (αGalCer), activates invariant NK T cells and acts as an adjuvant. We previously identified a fluorinated phenyl ring-modified αGalCer analog, 7DW8-5, displaying nearly 100-fold stronger CD1d binding affinity. In the current study, 7DW8-5 was found to exert a more potent adjuvant effect than αGalCer for a vaccine based on radiation-attenuated sporozoites of a rodent malaria parasite, Plasmodium yoelii, also referred to as irradiated P. yoelii sporozoites (IrPySpz). 7DW8-5 had a superb adjuvant effect only when the glycolipid and IrPySpz were conjointly administered i.m. Therefore, we evaluated the effect of distinctly different biodistribution patterns of αGalCer and 7DW8-5 on their respective adjuvant activities. Although both glycolipids induce a similar cytokine response in sera of mice injected i.v., after i.m. injection, αGalCer induces a systemic cytokine response, whereas 7DW8-5 is locally trapped by CD1d expressed by dendritic cells (DCs) in draining lymph nodes (dLNs). Moreover, the i.m. coadministration of 7DW8-5 with IrPySpz results in the recruitment of DCs to dLNs and the activation and maturation of DCs. These events cause the potent adjuvant effect of 7DW8-5, resulting in the enhancement of the CD8(+) T cell response induced by IrPySpz and, ultimately, improved protection against malaria. Our study is the first to show that the colocalization of a CD1d-binding invariant NK T cell-stimulatory glycolipid and a vaccine, like radiation-attenuated sporozoites, in dLN-resident DCs upon i.m. conjoint administration governs the potency of the adjuvant effect of the glycolipid.

Topics: Adjuvants, Immunologic; Animals; Antigens, CD1d; CD8-Positive T-Lymphocytes; Cytokines; Dendritic Cells; Female; Galactosylceramides; Lymph Nodes; Lymphocyte Activation; Malaria; Malaria Vaccines; Mice; Mice, Inbred BALB C; Mice, Transgenic; Natural Killer T-Cells; Plasmodium yoelii; Protein Binding; Sporozoites

We have previously shown that the C-glycoside analog of alpha-galactosylceramide (alpha-GalCer), alpha-C-GalCer, displays a superior inhibitory activity against the liver stages of the rodent malaria parasite Plasmodium yoelii than its parental glycolipid, alpha-GalCer. In this study, we demonstrate that NK cells, as well as IL-12, are a key contributor for the superior activity displayed by alpha-C-GalCer. Surprisingly, the diminished production of Th2 cytokines, including IL-4, by alpha-C-GalCer has no affect on its superior therapeutic activity relative to alpha-GalCer. Finally, we show that the in vivo administration of alpha-C-GalCer induces prolonged maturation of dendritic cells (DCs), as well as an enhanced proliferative response of mouse invariant Valpha14 (Valpha14i) NKT cells, both of which may also contribute to some degree to the superior activity of alpha-C-GalCer in vivo.

Topics: Animals; Antimalarials; Cell Differentiation; Cell Proliferation; Dendritic Cells; Down-Regulation; Galactosylceramides; Glycosides; Interleukin-10; Interleukin-12; Interleukin-4; Killer Cells, Natural; Lymphocyte Activation; Malaria; Mice; Mice, Inbred BALB C; Mice, Inbred C57BL; Models, Immunological; Monosaccharides; Receptors, Antigen, T-Cell; Th2 Cells