Dendritic cell activation and T cell priming with adjuvant- and antigen-loaded oxidation-sensitive polymersomes

While current subunit vaccines successfully induce humoral immune responses, a need exists for vaccine strategies to elicit strong cell-mediated immunity to address diseases such as cancer and chronic viral infection. Polymersomes are stable vesicles composed of self-assembling block copolymers with tunable degradation properties allowing delivery of both hydrophilic (within vesicle interior) or hydrophobic (within vesicle membrane) payload molecules. Here we apply oxidation-sensitive nanoscale polymersomes for both antigen and adjuvant delivery to dendritic cell (DC) endosomes. Calcein-loaded polymersomes were observed to release their payload initially in multiple DC endosomal compartments and subsequently within the cytosol. With either the Toll-like receptor agonists gardiquimod or R848 as payloads within the polymersomes, release resulted in DC activation, as indicated by induction of inflammatory cytokine expression and upregulation of DC maturation surface markers: for example, the ability of gardiquimod to induce IL-6 and IL-12 cytokine expression by DCs was enhanced 10-fold when loaded within polymersomes. With the model antigen ovalbumin as a payload, release resulted in CD8(+) T cell cross-priming by promoting protein antigen cross-presentation through MHC I, as indicated by activation of OT-I CD8(+) T cells. Our results demonstrate that oxidation-sensitive polymersomes can function as a vaccine delivery platform for inducing cell-mediated antigen-specific immune responses. (C) 2012 Elsevier Ltd. All rights reserved.

Development of a nano-adjuvant cancer vaccine and its evaluation for melanoma in combination with radiotherapy

Sylvie Hauert

Cancer is the second leading cause of death in the world and melanoma is the deadliest type of skin cancer. Although surgery, radiotherapy and chemotherapy are still standard treatments, the discovery of the role played by the immune system in cancer has allowed the development of new treatments, called immunotherapies. The goal of these treatments is to help the immune system eradicate cancerous cells, for example by increasing the anti-tumor response of the patient. In this particular case, the treatment has to activate cytotoxic CD8+ and CD4+ helper T cells against the cancer cells. This can be done by using subunit vaccines composed of tumor antigens, adjuvants and a delivery system, which will be internalized by dendritic cells (DCs) and induce its activation followed by the migration to the lymph nodes where it will educate T cells against specific antigens. Our laboratory has developed two different delivery systems, nanoparticles (NPs) and polymersomes (PSs) that can enhance the vaccineâs immune response by efficiently entering the lymphatic system, due to their size, and drain to the lymph node. Once they reach that location, they will be internalized by DCs and induce an anti-tumor response. In this thesis, we used these two nanocarriers to create a vaccine composed of different nano-adjuvants capable of activating several toll-like receptors simultaneously and test their efficacy at inducing an anti-tumor response in melanoma. We have developed and characterized the different nano-adjuvants, PS-MPLA, PS-CL075 and NP-CpG-B, and demonstrated, in vitro, synergistic effects on DC activation when PS-MPLA + PS-CL075 and PS-MPLA + NP-CpG-B were combined. In vivo, we showed the enhanced immune response with the different nano-adjuvant combinations, but only PS-MPLA + NP-CpG-B was able to delay tumor growth in melanoma. We then tested this vaccine in combination with radiotherapy, mimicking a clinical situation. We first demonstrated an enhanced immune response when combining a high irradiation dose, 15 Gy, with the nano-adjuvant vaccine draining the tumor-draining lymph node. Moreover, the vaccination of NP-CpG-B + PS-MPLA and radiotherapy increased mice survival by 17 days compared to mice only receiving radiotherapy. â Overall, we have demonstrated that combining different nano-adjuvants, targeting the tumor-draining lymph node, with radiotherapy enhanced significantly the survival in a melanoma model. This approach is particularly promising since ionizing radiation is a standard treatment in cancer and our vaccine can be applied to a multitude of cancer since it does not contain any antigen and its composition can easily be modified.

EPFL2018

Nanoparticle conjugation of CpG enhances adjuvancy for cellular immunity and memory recall at low dose

Marie Ballester, Alexandre de Titta, Jeffrey Alan Hubbell, Laura Jeanbart, Ziad Julier, Melody Swartz

In subunit vaccines, strong CD8(+) T-cell responses are desired, yet they are elusive at reasonable adjuvant doses. We show that targeting adjuvant to the lymph node (LN) via ultrasmall polymeric nanoparticles (NPs), which rapidly drain to the LN after intradermal injection, greatly enhances adjuvant efficacy at low doses. Coupling CpG-B or CpG-C oligonucleotides to NPs led to better dual-targeting of adjuvant and antigen (codelivered on separate NPs) in cross-presenting dendritic cells compared with free adjuvant. This led to enhanced dendritic cell maturation and T helper 1 (Th1)-cytokine secretion, in turn driving stronger effector C8(+) T-cell activation with enhanced cytolytic profiles and, importantly, more powerful memory recall. With only 4 mu g CpG, NP-CpG-B could substantially protect mice from syngeneic tumor challenge, even after 4 mo of vaccination, compared with free CpG-B. Together, these results show that nanocarriers can enhance vaccine efficacy at a low adjuvant dose for inducing potent and long-lived cellular immunity.

Natl Acad Sciences2013

Targeting the tumor-draining lymph node with adjuvanted nanoparticles reshapes the anti-tumor immune response

Jeffrey Alan Hubbell, Amanda Waite Lund, Melody Swartz, Susan Thomas, Efthymia Vokali

Accumulating evidence implicates the tumor-draining lymph node (TDLN) in tumor-induced immune escape, as it drains regulatory molecules and leukocytes from the tumor microenvironment. We asked whether targeted delivery of adjuvant to the TDLN, presumably already bathed in tumor antigens, could promote anti-tumor immunity and hinder tumor growth. To this end, we used 30 nm polymeric nanoparticles (NPs) that effectively target dendritic cells (DCs, CD11c(+)) within the lymph node (LN) after intradermal administration. These NPs accumulated within the TDLN when administered in the limb ipsilateral (i.l.) to the tumor or in the non-TDLN when administered in the contralateral (c.l.) limb. Incorporating the adjuvants CpG or paclitaxel into the NPs (CpG-NP and PXL-NP) induced DC maturation in vitro. When administered daily a and thus targeting the TDLN of a B16-F10 melanoma, adjuvanted NPs induced DC maturation within the TDLN and reshaped the CD4(+) T cell distribution within the tumor towards a Th1 (CXCR3(+)) phenotype. Importantly, this also led to an increase in the frequency of antigen-specific CD8(+) T cells within the tumor. This correlated with slowed tumor growth, in contrast to unhindered tumor growth after c.l. delivery of adjuvanted NPs (targeting a non-TDLN) or i.l. delivery of free adjuvant. CpG-NP treatment in the i.l. limb also was associated with an increase in CD8(+)/cD4(+) T cell ratios and frequencies of activated (CD25(+)) CD8(+) T cells within the TDLN whereas PXL-NP treatment reduced the frequency of regulatory T (FoxP3(+) CD4(+)) cells in the TDLN. Together, these data implicate the TDLN as a delivery target for adjuvant therapy of solid tumors. (C) 2013 The Authors. Published by Elsevier Ltd. All rights reserved.

Elsevier Sci Ltd2014

Development of a nano-adjuvant cancer vaccine and its evaluation for melanoma in combination with radiotherapy

Sylvie Hauert

EPFL2018