Nanobody-liposomes as novel cancer vaccine platform to efficiently stimulate T cell immunity.

Cancer vaccines can be utilized in combination with checkpoint inhibitors to optimally stimulate the anti-tumor immune response. Uptake of vaccine antigen by antigen presenting cells (APCs) is a prerequisite for T cell priming, but often relies on non-specific mechanisms. Here, we have developed a novel vaccination strategy consisting of cancer antigen-containing liposomes conjugated with CD169- or DC-SIGN-specific nanobodies (single domain antibodies) to achieve specific uptake by APCs. Our studies demonstrate efficient nanobody liposome uptake by human and murine CD169+ and DC-SIGN+ APCs in vitro and in vivo when compared to control liposomes or liposomes with natural ligands for CD169 and DC-SIGN. Uptake of CD169 nanobody liposomes resulted in increased T cell activation by human APCs and stimulated naive T cell priming in mouse models. In conclusion, while nanobody liposomes have previously been utilized to direct drugs to tumors, here we show that nanobody liposomes can be applied as vaccination strategy that can be extended to other receptors on APCs in order to elicit a potent immune response against tumor antigens.

Liposome induction of CD8+ T cell responses depends on CD169+ macrophages and Batf3-dependent dendritic cells and is enhanced by GM3 inclusion.

Cancer vaccines aim to efficiently prime cytotoxic CD8+ T cell responses which can be achieved by vaccine targeting to dendritic cells. CD169+ macrophages have been shown to transfer antigen to dendritic cells and could act as an alternative target for cancer vaccines. Here, we evaluated liposomes containing the CD169/Siglec-1 binding ligand, ganglioside GM3, and the non-binding ligand, ganglioside GM1, for their capacity to target antigens to CD169+ macrophages and to induce immune responses. CD169+ macrophages demonstrated specific uptake of GM3 liposomes in vitro and in vivo that was dependent on a functional CD169 receptor. Robust antigen-specific CD8+ and CD4+ T and B cell responses were observed upon intravenous administration of GM3 liposomes containing the model antigen ovalbumin in the presence of adjuvant. Immunization of B16-OVA tumor bearing mice with all liposomes resulted in delayed tumor growth and improved survival. The absence of CD169+ macrophages, functional CD169 molecules, and cross-presenting Batf3-dependent dendritic cells (cDC1s) significantly impaired CD8+ T cell responses, while B cell responses were less affected. In conclusion, we demonstrate that inclusion of GM3 in liposomes enhance immune responses and that splenic CD169+ macrophages and cDC1s are required for induction of CD8+ T cell immunity after liposomal vaccination.

Early cellular interactions and immune transcriptome profiles in human factor VIII-exposed hemophilia A mice.

Essentials Initial immune cell interactions leading to factor (F) VIII immunity are not well characterized. We assessed cellular interactions and expression profiles in hemophilia A mice. MARCO+, followed by SIGLEC1+ and SIGNR1+ macrophages co-localize most with human FVIII. The splenic transcriptome highlights potential therapeutic targets to prevent inhibitors. SUMMARY: Background Developing factor VIII (FVIII) inhibitory antibodies is the most serious complication in hemophilia A treatment, representing a significant health and economic burden. A better understanding of the early events in an immune response leading to this outcome may provide insight into inhibitor development. Objective To identify early mediators of FVIII immunity and to detail immune expression profiles in the spleen and liver. Methods C57Bl/6 F8 E16 knockout mice were infused with 5-20 µg (2000-8000 IU kg-1 ) of recombinant FVIII. Spleens were frozen at various time-points post-infusion and stained for FVIII and cellular markers. Splenic and liver RNA expression analysis was performed 3 h post-infusion of 0.6 µg (240 IU kg-1 ) FVIII by nCounter technology using a 561-gene immunology panel. Results FVIII localization in the spleen did not change over 2.5 h. We observed significantly higher co-localization of FVIII with MARCO+ cells compared with SIGLEC1+ and SIGNR1+ in the splenic marginal zone. FVIII exhibited little co-localization with CD11c+ dendritic cells and the macrophage mannose receptor, CD206. Following FVIII infusion, the splenic mRNA profiling identified genes such as Tnfaip6 and Il23r, which are implicated in chemotaxis and a proinflammatory Th17 response, respectively. In contrast, an upregulation of Gfi1 in the liver suggests an anti-inflammatory environment. Conclusions FVIII co-localizes predominantly with marginal zone macrophages (MARCO+ ) in the murine spleen following intravenous infusion. Targeting pathways that are implicated in the early FVIII innate immune response in the spleen may lead to therapeutic interventions to prevent inhibitor formation.

Excreted/secreted Trichuris suis products reduce barrier function and suppress inflammatory cytokine production of intestinal epithelial cells.

The administration of helminths is considered a promising strategy for the treatment of autoimmune diseases due to their immunomodulatory properties. Currently, the application of the helminth Trichuris suis as a treatment for Crohn's disease is being studied in large multi-center clinical trials. The intestinal epithelium forms an efficient barrier between the intestinal lumen containing the microbial flora and helminths, and dendritic cells (DCs) present in the lamina propria that determine the TH response. Here, we investigated how excreted/secreted (E/S) products of T. suis affect the barrier function of intestinal epithelial cells (IECs) in order to reach the DCs and modulate the immune response. We show that T. suis E/S products reduce the barrier function and the expression of the tight junction proteins EMP-1 and claudin-4 in IEC CMT93/69 monolayers in a glycan-dependent manner. This resulted in an increased passage of soluble compounds to the basolateral side that affected DC function. In addition, T. suis E/S suppressed LPS-induced pro-inflammatory cytokine production by CMT93/69 cells, whereas the production of the TH2 response-inducing cytokine thymic stromal lymphopoietin (TSLP) was induced. Our studies indicate that T. suis E/S glycans affect the function of the intestinal epithelium in order to modulate DC function. Identification of the T. suis E/S glycans that modulate IEC and DC function may lead to a strategy to reduce symptoms of autoimmune and allergic immune diseases by orally administrated helminth-derived factors without the need of infection with live helminths.