Adjuvant-free immunization with infective filarial larvae as lymphatic homing antigen carriers

International audienceControlled infection with intestinal nematodes has therapeutic potential for preventing the symptoms of allergic and autoimmune diseases. Here, we engineered larvae of the filarial nematode Litomosoides sigmodontis as a vaccine strategy to induce adaptive immunity against a foreign, crosslinked protein, chicken egg ovalbumin (OVA), in the absence of an external adjuvant. The acylation of filarial proteins with fluorescent probes or biotin was not immediately detrimental to larval movement and survival, which died 3 to 5 days later. At least some of the labeled and skin-inoculated filariae migrated through lymphatic vessels to draining lymph nodes. The immunization potential of OVA-biotin-filariae was compared to that of an OVA-bound nanoparticulate carrier co-delivered with a CpG adjuvant in a typical vaccination scheme. Production of IFNγ and TNFα by restimulated CD4+ cells but not CD8+ confirmed the specific ability of filariae to stimulate CD4+ T cells. This alternative method of immunization exploits the intrinsic adjuvancy of the attenuated nematode carrier and has the potential to shift the vaccination immune response towards cellular immunity

Peripherally Administered Nanoparticles Target Monocytic Myeloid Cells, Secondary Lymphoid Organs and Tumors in Mice

Nanoparticles have been extensively developed for therapeutic and diagnostic applications. While the focus of nanoparticle trafficking in vivo has traditionally been on drug delivery and organ-level biodistribution and clearance, recent work in cancer biology and infectious disease suggests that targeting different cells within a given organ can substantially affect the quality of the immunological response. Here, we examine the cell-level biodistribution kinetics after administering ultrasmall Pluronic-stabilized poly(propylene sulfide) nanoparticles in the mouse. These nanoparticles depend on lymphatic drainage to reach the lymph nodes and blood, and then enter the spleen rather than the liver, where they interact with monocytes, macrophages and myeloid dendritic cells. They were more readily taken up into lymphatics after intradermal (i.d.) compared to intramuscular administration, leading to similar to 50% increased bioavailability in blood. When administered i.d., their distribution favored antigen-presenting cells, with especially strong targeting to myeloid cells. In tumor-bearing mice, the monocytic and the polymorphonuclear myeloid-derived suppressor cell compartments were efficiently and preferentially targeted, rendering this nanoparticulate formulation potentially useful for reversing the highly suppressive activity of these cells in the tumor stroma

Engineering Approaches to Immunotherapy

As the science of immunology grows increasingly mechanistic, motivation for developing quantitative, design-based engineering approaches has also evolved, both for therapeutic interventions and for elucidating immunological pathways in human disease. This has seeded the nascent field of "immunoengineering," which seeks to apply engineering analyses and design approaches to problems in translational immunology. For example, cell engineers are creating ways to tailor and use immune cells as living therapeutics; protein engineers are devising new methods of rapid antibody discovery; biomaterials scientists are guiding vaccine delivery and immune-cell activation with novel constructs; and systems immunologists are deciphering the evolution and maintenance of T and B cell receptor repertoires, which could help guide vaccine design. The field is multidisciplinary and collaborative, with engineers and immunologists working together to better understand and treat disease. We discuss the scientific progress in this young, yet rapidly evolving research area, which has yielded numerous start-up companies that are betting on impact in clinical and commercial translation in the near future

Coupled As and Mn Redox Transformations in an Fe(0) Electrocoagulation System: Competition for Reactive Oxidants and Sorption Sites

Iron electrocoagulation (EC) can be used for the decentralized treatment of arsenic(As)-contaminated groundwater. Iron EC involves the electrolytic dissolution of an Fe(0) electrode to Fe(II). This process produces reactive oxidants, which oxidize As(III) and Fe(II) to As(V) and a range of Fe(III) (oxyhydr)oxide phases. Here, we investigated the impact of manganese (Mn) on As removal, since the two often co-occur in groundwater. In the absence of Mn(II), we observed rapid As(III) oxidation and the formation of As(V)-Fe(III) polymers. Arsenic removal was achieved upon aggregation of the As(V)-Fe(III) polymers. In the presence of Mn, the mechanism of As removal varied with pH. At pH 4.5, As(III) was oxidized rapidly by OH center dot and the aggregation of the resulting As(V)-Fe(III) polymers was enhanced by the presence of Mn. At pH 8.5, As(III) and Mn(II) competed for Fe(IV), which led As(III) to persist in solution. The As(V) that did form was incorporated into a mixture of As(V)-Fe(III) polymers and a ferrihydrite-like phase that incorporated 8% Mn(III); some As(III) was also sorbed by these phases. At intermediate pH values, As(III) and Mn(II) also competed for the oxidants, but Mn(III) behaved as a reactive intermediate that reacted with Fe(II) or As(III). This result can explain the presence of As(V) in the solid phase. This detailed understanding of the As removal mechanisms in the presence of Mn can be used to tune the operating conditions of Fe EC for As removal under typical groundwater conditions

Antigen delivery to dendritic cells by poly(propylene sulfide) nanoparticles with disulfide conjugated peptides: Cross-presentation and T cell activation

Vaccines aiming to activate cytotoxic T cells require cross-presentation of exogenous antigen by antigen-presenting cells (APCs). We recently developed a synthetic nanoparticle vaccine platform that targets lymph node-resident dendritic cells (DCs), capable of mounting an immune response to conjugated antigen. Here, we explore routes of processing and the efficiency of MHC I cross-presentation of OVA peptides conjugated using both reducible and non-reducible linkages, exploring the hypothesis that reduction-sensitive conjugation will lead to better antigen cross-presentation. Both clathrin and macropinocytic pathways were implicated in nanoparticle uptake by colocalization and inhibitor studies. Cross-presentation by DCs was demonstrated by direct antibody staining and in vitro stimulation of CD8(+) T cells from OT-I mice and was indeed most efficient with the reduction-sensitive conjugation. Similarly, we observed IFN-γ production by CD4(+) T cells from OT-II mice. Finally, immunization with the OVA peptide-bearing nanoparticles resulted in in vivo proliferation and IFN-γ production by adoptively transferred CD8(+) OT-I T cells and was also most efficient with reduction-sensitive linking of the peptide antigen. These results demonstrate the relevance of the poly(propylene sulfide) nanoparticle vaccine platform and antigen conjugation scheme for activating both cytotoxic and helper T cell responses

Polymer micelles with pyridyl disulfide-coupled antigen travel through lymphatics and show enhanced cellular responses following immunization

Poly(ethylene glycol)-stabilized poly(propylene sulfide) core (PEG-PPS) nanoparticles (NPs) smaller than 50 nm efficiently travel to draining lymph nodes and interact with antigen-presenting cells (APCs) to induce potent immune responses following intradermal immunization. To determine if a similar system could be developed that could be more easily and reproducibly prepared and eliminated faster in vivo, we created block copolymers of PEG-bl-PPS capable of self-assembling into 25-35 nm micelles (MCs). Biodistribution studies showed that these MCs were able to travel to draining lymph nodes, where they preferentially interacted with APCs. To couple cysteine-containing antigens to the surface of the MCs, a new polymer was synthesized with a terminal pyridyl disulfide (PDS), forming PDS-PEG-bl-PPS-benzyl. When mice were immunized in conjunction with free CpG as an adjuvant, ovalbumin-conjugated MCs (MC-Ova) generated more (2.4-fold) Ova-specific CD8(+) T cells in the blood and higher (1.7-fold) interferon-gamma levels from splenocytes upon restimulation than in mice immunized with free Ova and CpG. When comparing this MC platform to our PEG-PPS NPs with disulfide-linked Ova, no significant differences were found in the measured responses. These results indicate that PDS-functionalized MCs are efficient antigen delivery vehicles that enhance immune responses compared to immunization with free protein. (C) 2012 Acts Materialia Inc. Published by Elsevier Ltd. All rights reserved

Synthetically glycosylated antigens induce antigen-specific tolerance and prevent the onset of diabetes

Homeostatic antigen presentation by hepatic antigen-presenting cells, which results in tolerogenic T-cell education, could be exploited to induce antigen-specific immunological tolerance. Here we show that antigens modified with polymeric forms of either N-acetylgalactosamine or N-acetylglucosamine target hepatic antigen-presenting cells, increase their antigen presentation and induce antigen-specific tolerance, as indicated by CD4(+) and CD8(+) T-cell deletion and anergy. These synthetically glycosylated antigens also expanded functional regulatory Tcells, which are necessary for the durable suppression of antigen-specific immune responses. In an adoptive-transfer mouse model of type-1 diabetes, treatment with the glycosylated autoantigens prevented T-cell-mediated diabetes, expanded antigen-specific regulatory T cells and resulted in lasting tolerance to a subsequent challenge with activated diabetogenic T cells. Glycosylated autoantigens targeted to hepatic antigen-presenting cells might enable therapies that promote immune tolerance in patients with autoimmune diseases