Nanoparticle conjugation of antigen enhances cytotoxic T-cell responses in pulmonary vaccination

Abstract

The ability of vaccines to induce memory cytotoxic T-cell responses in the lung is crucial in stemming and treating pulmonary diseases caused by viruses and bacteria. However, most approaches to subunit vaccines produce primarily humoral and only to a lesser extent cellular immune responses. We developed a nanoparticle (NP)-based carrier that, upon delivery to the lung, specifically targets pulmonary dendritic cells, thus enhancing antigen uptake and transport to the draining lymph node; antigen coupling via a disulfide link promotes highly efficient cross-presentation after uptake, inducing potent protective mucosal and systemic CD8 + Tcell immunity. Pulmonary immunization with NP-conjugated ovalbumin (NP-ova) with CpG induced a threefold enhancement of splenic antigen-specific CD8 + T cells displaying increased CD107a expression and IFN-γ production compared with immunization with soluble (i.e., unconjugated) ova with CpG. This enhanced response was accompanied by a potent Th17 cytokine profile in CD4 + T cells. After 50 d, NP-ova and CpG also led to substantial enhancements in memory CD8 + T-cell effector functions. Importantly, pulmonary vaccination with NP-ova and CpG induced as much as 10-fold increased frequencies of antigen-specific effector CD8 + T cells to the lung and completely protected mice from morbidity following influenza-ova infection. Here, we highlight recruitment to the lung of a long-lasting pool of protective effector memory cytotoxic T-cells by our disulfide-linked antigen-conjugated NP formulation. These results suggest the reduction-reversible NP system is a highly promising platform for vaccines specifically targeting intracellular pathogens infecting the lung.adjuvant | antigen trafficking | T lymphocyte | prophylactic | antigen conjugation

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

“…One of the features expected by a prophylactic cellular immunity-inducing vaccine is induction of memory T cells that can be clonally expanded on recall (30). We first primed and boosted mice with our formulations to generate a pool of functional memory CTLs (14). Two months later, we evaluated the activation of these memory CTLs in the spleen (Fig.…”

“…Moreover, CpG-A and CpG-B classes have been suggested to exert different functions on naive versus memory CD8 + T cells in vitro (38). To evaluate whether our formulations were inducing different phenotypes of memory CD8 + T cells in vivo, we first primed and boosted mice with NP-OVA with CpG-B to generate a pool of functional memory CTLs, as previously shown in our laboratory (14). At least 2 mo later, we then evaluated the activation and phenotype of these memory CTLs by the different formulations when coinjected with NP-OVA.…”

“…Nanocarriers can be used to modulate the immune response induced by antigens and adjuvants by modifying their characteristics, such as stability, tissue and cell targeting, and DC-activating capacity (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12). We have previously described the targeting benefits of conjugating antigens to ultrasmall Pluronic-stabilized poly(propylene sulfide) (PPS) nanoparticles (NPs) in terms of CD8 + T-cell and Th1 responses (13,14). The hydrophobic PPS core is hydrolytically stable, allowing wet storage, yet is oxidized to products that are soluble in vivo (15,16).…”

Intracellular Cleavable CpG Oligodeoxynucleotide-Antigen Conjugate Enhances Anti-tumor Immunity

“…These include particulate and soluble formulations where either the antigen or adjuvant was conjugated with a reversible linker onto either a nanoparticle or a polymer carrier. 8,10,[22][23][24][25][26][27][28] The redoxresponsive disulphide bond was selected as a conjugate linker to achieve triggered release of the antigen from the adjuvant once the soluble conjugate was delivered inside the cell. The disulphide bond can be cleaved through the thiol-disulphide exchange reactions with a redox molecule such as glutathione (GSH), which is found at millimolar concentrations (0.5-10 mM) in intracellular compartments, while its concentration is much lower in extracellular milieu (2-40 mM).…”

Enhancing Efficacy of Anticancer Vaccines by Targeted Delivery to Tumor-Draining Lymph Nodes

“…Ultrasmall, functionalizable nanoparticles (NP) developed in our laboratory effectively target DCs in skin-draining LNs upon intradermal delivery (20,21). These nanoparticles lead to antigen crosspresentation by DCs and to enhanced cytotoxic antigenspecific CD8 þ T-cell immunity when coupled with an antigen or an adjuvant (22)(23)(24).…”