Targeted antigen delivery and activation of dendritic cells in vivo: steps towards cost effective vaccines

Item does not contain fulltextDuring the past decade, the immunotherapeutic potential of ex vivo generated professional antigen presenting dendritic cells (DCs) has been explored in the clinic. Albeit safe, clinical results have thus far been limited. A major disadvantage of current cell-based dendritic cell (DC) therapies, preventing universal implementation of this form of immunotherapy, is the requirement that vaccines need to be tailor made for each individual. Targeted delivery of antigens to DC surface receptors in vivo would circumvent this laborious and expensive ex vivo culturing steps involved with these cell-based therapies. In addition, the opportunity to target natural and often rare DC subsets in vivo might have advantages over loading more artificial ex vivo cultured DCs. Preclinical studies show targeting antigens to DCs effectively induces humoral responses, while cellular responses are induced provided a DC maturation or activation stimulus is co-administered. Here, we discuss strategies to target antigens to distinct DC subsets and to simultaneously employ adjuvants to activate these cells to induce immunity

Targeting antigens to dendritic cells in vivo.

Contains fulltext : 50386.pdf (publisher's version ) (Closed access)Dendritic cells (DCs) play a key role in antigen-specific immune regulation. DCs take up and process antigens and present these as peptides through MHC molecules to T cells. Recent pre-clinical and clinical studies have exploited DCs as a means to improve vaccine efficiency. In these studies, monocyte-derived autologous DCs are loaded ex vivo with antigens and re-administered to the patient. These tailor-made vaccines are costly and labor intensive, and therefore less suitable for large-scale immunization programs. As a next step in the development of DC vaccines, it is proposed to load DCs with antigens in vivo. Drug delivery systems harboring antigens have been targeted to DCs via specific surface receptors preferentially expressed by DCs, resulting in priming of humoral and cellular immune responses. The present review focuses on the various antigen delivery systems that are currently in use and the DC surface receptors they target

The influence of PEG chain length and targeting moiety on antibody-mediated delivery of nanoparticle vaccines to human dendritic cells

Item does not contain fulltextTargeted delivery of nanoparticles (NPs) carrying vaccine components to dendritic cells (DCs) is a promising strategy to initiate antigen-specific immune responses. Improving the interactions between nanoparticle-carried ligands and receptors on DCs is a major challenge. These NPs are generally coated with poly(ethylene glycol) (PEG), to shield non-specific interactions, and antibodies, to facilitate specific delivery to DC surface receptors. We have devised a strategy to covalently link PEG molecules of various chain length (Mw 2000-20000 g/moL) to poly(lactic-co-)glycolic acid (PLGA) NP vaccines. We coated these NPs with various antibodies recognizing the DC-specific receptor DC-SIGN to study the effects of shielding and antibody type on antibody--receptor interactions. Chemical attachment of PEG to the particle surface was followed by detailed zeta potential, DLS and NMR studies, and analyzed by analytical chemistry. Increasing the PEG chain length increased particle size and polydispersity index and reduced the intracellular degradation rate of encapsulated antigens. Binding and uptake of NPs by human DCs was affected by both PEG chain length and antibody type. NPs coated with PEG-3000 had the optimal chain length for antibody--receptor interactions and induction of antigen-specific T-cell responses. Interestingly, clear differences were observed upon targeting distinct epitopes of the same receptor. Binding and uptake of NPs carrying antibodies recognizing the carbohydrate recognition domain of DC-SIGN was enhanced when compared to those carrying antibodies recognizing the receptor's neck region. In conclusion, our data show that PEG chains cannot be extended beyond a certain length for shielding purposes without compromising the efficacy of targeted delivery. Thereby, the implications of our findings are not limited to the future design of nanovaccines specifically targeted to DC-SIGN, but apply to the general design of targeted nanocarriers

Modulating effects of thyroid state on the induction of biotransformation enzymes byu 2,3,7,8-tetrachlorodibenzo-p-dioxin.

In this study we investigated to what extent the induction of detoxification enzymes by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is modulated by concomitant TCDD-induced changes in thyroid state. Euthyroid (Eu) male Sprague-Dawley rats, surgically thyroidectomized (Tx) rats and Tx rats receiving substitution doses of 3,3',5-triiodothyronine (Tx T3) or thyroxine (Tx T4) by osmotic minipumps were treated with a single ip injection of 10 g TCDD/kg/bwt or with vehicle (corn oil). Three days after TCDD administration, rats were sacrificed and blood and livers were collected for analysis. Total hepatic cytochrome P450 (CYP) content was increased by ~50% by TCDD in all groups but was not affected by thyroid state. In Eu rats, TCDD increased CYP1A1/1A2 activity 90-fold, CYP1A1 protein content 52-fold and CYP1A1 mRNA levels ~5.8-fold. Similar findings were obtained in Tx, Tx T3 and Tx T4 rats except that TCDD-induced CYP1A1 activity was significantly decreased in Tx rats. NADPH cytochrome P450 reductase activity was not affected by TCDD but was decreased in Tx rats, which may explain the diminished TCDD-induced CYP1A1 activity in Tx rats. Hepatic p-nitrophenol UDP-glucuronyltransferase (UGT) activity was induced ~4-fold by TCDD in Eu rats. Similar basal and TCDD-induced activities were observed in Tx T3 and Tx T4 rats, but TCDD-induced activities were significantly lower in Tx rats. TCDD did not have a significant effect on overall glutathione-S-transferase (GST) activity or hepatic GST 2-2, 3-3 or 4-4 protein levels but produced a marked increase in GST 1-1 protein levels. Thyroid state did not affect basal or TCDD-induced GST activity or subunit pattern. Iodothyronine sulfotransferase (ST) activity was not affected by TCDD treatment and was slightly but not significantly lower in Tx rats than in Eu, Tx T3 and Tx T4 rats. These results suggest that the changes in thyroid hormone levels associated with TCDD treatment have little modulating effects on the induction of hepatic detoxification enzymes in Sprague-Dawley rats exposed to this compound

Integration in design and manufacturing of polymer smart devices

Integration of functions in single components is pursued in order to manufacture smaller and smarter polymer micro devices at less cost, through e.g. less assembly steps. It requires integration on both product and production side. This paper addresses the use of molded interconnect device (MID) technology for the integration of electronic circuitry into polymer products. Shown will be new approaches of selective metallization for creating conductive tracks. The supply chain of MID parts is still seen as vulnerable, resulting in concerns on reliability of production and product. A solution is integration of processes in one production cell. Shown is the feasibility of integrating a surface patterning process into an injection molding tool

Targeting nanoparticles to dendritic cells for immunotherapy.

Item does not contain fulltextDendritic cells (DCs) are key players in the initiation of adaptive immune responses and are currently exploited in immunotherapy for treatment of cancer and infectious diseases. Development of targeted nanodelivery systems carrying vaccine components, including antigens and adjuvants, to DCs in vivo represents a promising strategy to enhance immune responses. Delivering particulate vaccines specifically to DCs and preventing nonspecific uptake by other endocytotic cells are challenging. Size represents a critical parameter determining whether particulate vaccines can penetrate lymph nodes and reach resident DCs. Specific delivery is further enhanced by actively targeting DC-specific receptors. This chapter discusses the rationale for the use of particle-based vaccines and provides an overview of antigen-delivery vehicles currently under investigation. In addition, we discuss how vaccine delivery systems may be developed, focusing on liposomes, PLGA polymers, and gold nanoparticles, to obtain safe and efficacious vaccines

Activation of human plasmacytoid dendritic cells by TLR9 impairs Fc gammaRII-mediated uptake of immune complexes and presentation by MHC class II.

Contains fulltext : 69513.pdf (publisher's version ) (Closed access)Human plasmacytoid dendritic cells (pDCs)(2) exploit Ag uptake receptors like CD32a for internalization of exogenous Ags. Activation of pDC by TLR9 ligand CpG-C induces strong maturation. Surprisingly, we observed that CpG-C-stimulated pDCs showed impaired Ag-specific T cell proliferation whereas the induction of allogeneic T cell proliferation was not affected. We demonstrated that signals from TLR9 caused a rapid down-regulation of the capacity of pDC to take-up Ab-Ag complexes without altering their CD32a expression, thus explaining the reduced Ag presentation. The recent contrasting biological responses that were observed upon TLR9 ligation in pDCs prompted us to study the effect of several TLR9 ligands. We observed that type I IFN-inducer CpG-A, localizing in the early endosomal compartment, did not affect CD32a function, whereas CpGs localizing in the late endosomes and inducing pDC maturation clearly inhibited CD32a-mediated Ag uptake and presentation. We conclude that TLR9 ligands not only determine the type of response, i.e., type I IFN production (innate immunity) or maturation (adaptive immunity), but also directly affect Ag presentation capacity of pDCs. We hypothesize that pDC, once activated via TLR9-ligands reaching the late endosomes, can only present initially sampled Ags and thus are protected from uptake and processing of additional potential self-Ags

Comparison of antibodies and carbohydrates to target vaccines to human dendritic cells via DC-SIGN.

Item does not contain fulltextVaccine efficacy is improved upon specific delivery to professional antigen (Ag) presenting cells, such as dendritic cells (DCs). Antigenicity and adjuvanticity of vaccine components can be enhanced by encapsulation within nanoparticle (NP) vaccine carriers that are targeted to the human DC-specific C-type lectin receptor DC-SIGN. Here we used two strategies to target vaccines components to DC-SIGN: 1) carbohydrates as natural receptor ligands and 2) receptor-specific antibodies (Abs). To determine the optimal targeting strategy, we coated NP vaccines harboring MHC class I or II-restricted Ags and the TLR ligands (TLRLs) poly I:C and resiquimod with either the DC-SIGN ligands Lewis-X (Le(x)), mannosylated lipoarabinomannan (ManLAM), glycosylated HIV protein gp120, or three distinct DC-SIGN Abs. Although, because of their lower MW, surface coating of NP vaccines with carbohydrates resulted in a higher number of surface molecules per NP than coating with Abs, NP vaccines carrying Abs were more effectively bound and internalized by human DCs than carriers harboring Le(x), ManLAM or gp120. Furthermore, NP vaccines harboring TLRLs triggered significant induction of DC maturation markers when compared to those without TLRLs, irrespective of the targeting moiety. Ab- and gp120-mediated targeting induced equally high levels of proinflammatory cytokines and increased presentation of the MHC class I-restricted epitope. By contrast, presentation of the MHC class II-restricted epitope was more efficient upon Ab-mediated targeting than when using gp120, Le(x) or ManLAM. From these findings we conclude that receptor-specific Abs are more effective than carbohydrates for DC-targeted vaccination strategies.1 juni 201

Controlled release of antigen and Toll-like receptor ligands from PLGA nanoparticles enhances immunogenicity

Item does not contain fulltextAIM: Dendritic cells rapidly capture nanoparticles and induce a potent cellular immune response. It is yet unknown whether the immunological response induced by slow release of encapsulated versus soluble antigen and adjuvant is superior. MATERIALS & METHODS: The kinetics of poly(lactic-co-glycolic acid) PLGA nanoparticles antigen release was studied by the DQ-bovine serum albumin (BSA) self-quenching antigen model. The immunological response induced was evaluated by means of dendritic cell activation/maturation markers, cytokine production and their ability to drive antigen-specific T-cell proliferation. RESULTS & CONCLUSION: PLGA-encapsulated antigen and adjuvant showed an enhanced T-cell response when compared with soluble vaccine components by increasing antigenicity and adjuvanticity. Although the kinetic profile followed the same pattern, encapsulation increased strength and duration of the response