In situloading of skin dendritic cells with apoptotic bleb-derived antigens for the induction of tumor-directed immunity

Abstract

The generation and loading of dendritic cells (DC) ex-vivo for tumor vaccination purposes is laborious and costly. Direct intradermal (i.d.) administration of tumor-associated antigens could be an attractive alternative approach, provided that efficient uptake and cross-presentation by appropriately activated skin DCs can be achieved. Here, we compare the efficiency of i.d. delivery of relatively small apoptotic blebs (diameter »0.1-1 mm) derived from MART-1 transduced acute myeloid leukemia (AML) HL60 cells, to that of larger apoptotic cell remnants (ACR; 2-10 mm) in a physiologically highly relevant human skin explant model. Injection of either fluorescently-labelled ACRs or blebs alone did not affect the number or distribution of migrated DC subsets from skin biopsies after 48 hours, but resulted in a general up-regulation of the co-stimulatory molecules CD83 and CD86 on skin DCs that had ingested apoptotic material. We have previously shown that i.d. administration of GM-CSF and IL-4 resulted in preferential migration of a mature and highly T cell-stimulatory CD11 hi CD1a C CD14 ¡ dermal DC subset. Here, we found that co-injection of GM-CSF and IL-4 together with either ACRs or blebs resulted in uptake efficiencies within this dermal DC subset of 7.6% ( §6.1%) and 19.1% ( §15.9%), respectively, thus revealing a significantly higher uptake frequency of blebs (P < 0.02). Intradermal delivery of tumor-derived blebs did not affect the T-cell priming and T H -skewing abilities of migratory skin DC. Nevertheless, in contrast to i.d. administration of ACR, the injection of blebs lead to effective cross-presentation of MART-1 to specific CD8 C effector T cells. We conclude that apoptotic bleb-based vaccines delivered through the skin may offer an attractive, and broadly applicable, cancer immunotherapy.

Glycan-Modified Apoptotic Melanoma-Derived Extracellular Vesicles as Antigen Source for Anti-Tumor Vaccination

“…Multiple studies have already reported on the ability of ApoEV-loaded DCs to induce antigen-specific CD8 + T cell responses [26,27,47]. Our unmodified ApoEVs were not able to induce robust MART-1 26–35 -specific CD8 + cell responses.…”

“…An abundant source of both patient-specific neo-antigens and shared tumor-associated antigens (TAAs) for vaccination purposes, without the need for prior knowledge of the personalized epitope repertoire, is the autologous tumor itself. We previously showed that apoptotic extracellular vesicles (ApoEVs) derived from tumor cells can induce antigen-specific T cell responses both in vitro and ex vivo [26,27]. ApoEVs are produced when cells undergo apoptosis, resulting in membrane blebbing, membrane protrusion, and apoptotic body (ApoBD) formation [28].…”

Differential capacity of human interleukin-4 and interferon-α monocyte-derived dendritic cells for cross-presentation of free versus cell-associated antigen

“…Tumor-derived “whole” cellular vaccines have therefore regained interest, especially with the recent insights in immunogenic cell death [ 21 ]. We have previously reported on the beneficial effects of using apoptotic AML-derived blebs as a source of TAA for in situ loading of skin DC [ 11 ], as well as MoDC loading in vitro [ 6 ]. As MoDC cultured in the presence of GM-CSF and IFNα have been described to have a higher capacity for the cross-presentation of antigens [ 13 , 14 , 22 , 23 ], they might constitute a more potent platform for the delivery of blebs in the context of DC vaccination strategies.…”

“…However, most DC subsets are capable of performing this task and appear to achieve this with similar efficacy [ 10 ]. Previously, we have reported that apoptotic blebs, derived from apoptotic AML cells, are a superior source of TAA for the in situ loading of human skin-resident DC, which take up and cross-present TAA from blebs to a higher degree as compared to ACR [ 11 ]. Moreover, IL-4 MoDC loaded with isolated apoptotic blebs increased CD4 + T cell proliferation and T helper (T H ) type I skewing (based on IFNγ production), as compared to using ACR; importantly, we have also shown that bleb-loaded IL-4 MoDC induce TAA-specific CD8 + T cells with higher avidity [ 6 ].…”

Preclinical Organotypic Models for the Assessment of Novel Cancer Therapeutics and Treatment

“…One strategy currently used is to load dendritic cells with tumor associated antigens, but the costs of generating these cells and treating them is extremely high. The use of skin tissue explants to load resident dendritic cells with tumor antigens in situ, has been successfully explored as an alternative method (Ruben et al 2014). Immune checkpoint inhibition has demonstrated promise in several malignancies, but successful treatment is dependent on infiltration of CD8 + T cells.…”