Dendritic Cell Function After Gene Transfer with Adenovirus-calcium Phosphate Co-precipitates

Multifunctional Nanoparticles in Precise Cancer Treatment: Considerations in Design and Functionalization of Nanocarriers

Nanotechnology has revolutionized cancer treatment in both diagnosis and therapy. Since the initial application of nanoparticles (NPs) in cancer treatment, the main objective of nanotechnology was developing effective nanosystems with high selectivity and specificity for cancer treatment and diagnosis. To achieve this, different encapsulation and conjugation strategies along with surface functionalization techniques have been developed to synthesize anticancer drugs loaded NPs with effective targeting to specific tumor cells. The unique physicochemical attributes of NPs make them promising candidates for targeted drug delivery, localized therapies, sensing, and targeting at cellular levels. However, a nanosystem for localized and targeted cancer managements should overcome several biological barriers and biomedical challenges such as endothelial barriers, blood brain barrier, reticuloendothelial system, selective targeting, biocompatibility, acute/chronic toxicity, tumor-targeting efficacy. The NPs for in vivo applications encounter barriers at system, organ, and the cellular level. To overcome these barriers, different strategies during the synthesis and functionalization of NPs should be adapted. Pharmacokinetics and cellular uptake of NPs are largely associated with physicochemical attributes of NPs, morphology, hydrodynamic size, charge, and other surface properties. These properties can be adjusted during different phases of synthesis and functionalization of the NPs. This study reviews the advances in targeted cancer treatment and the parameters influencing the efficacies of NPs as therapeutics. Different strategies for overcoming the biological barriers at cellular, organ and system levels and biomedical challenges are discussed. Moreover, the applications of NPs in preclinical and clinical practice are reviewed.

Oncolytic adenoviruses coated with MHC-I tumor epitopes increase the antitumor immunity and efficacy against melanoma

The stimulation of the immune system using oncolytic adenoviruses (OAds) has attracted significant interest and several studies suggested that OAds immunogenicity might be important for their efficacy. Therefore, we developed a versatile and rapid system to adsorb tumor-specific major histocompatibility complex class I (MHC-I) peptides onto the viral surface to drive the immune response toward the tumor epitopes. By studying the model epitope SIINFEKL, we demonstrated that the peptide-coated OAd (PeptiCRAd) retains its infectivity and the cross presentation of the modified-exogenous epitope on MHC-I is not hindered. We then showed that the SIINFEKL-targeting PeptiCRAd achieves a superior antitumor efficacy and increases the percentage of antitumor CD8⁺ T cells and mature epitope-specific dendritic cells in vivo. PeptiCRAds loaded with clinically relevant tumor epitopes derived from tyrosinase-related protein 2 (TRP-2) and human gp100 could reduce the growth of primary-treated tumors and secondary-untreated melanomas, promoting the expansion of antigen-specific T-cell populations. Finally, we tested PeptiCRAd in humanized mice bearing human melanomas. In this model, a PeptiCRAd targeting the human melanoma-associated antigen A1 (MAGE-A1) and expressing granulocyte and macrophage colony-stimulating factor (GM-CSF) was able to eradicate established tumors and increased the human MAGE-A1-specific CD8⁺ T cell population. Herein, we show that the immunogenicity of OAds plays a key role in their efficacy and it can be exploited to direct the immune response system toward exogenous tumor epitopes. This versatile and rapid system overcomes the immunodominance of the virus and elicits a tumor-specific immune response, making PeptiCRAd a promising approach for clinical testing.

Chapter eight--Oncolytic adenoviruses for cancer immunotherapy: data from mice, hamsters, and humans

Adenovirus is one of the most commonly used vectors for gene therapy and two products have already been approved for treatment of cancer in China (Gendicine(R) and Oncorine(R)). An intriguing aspect of oncolytic adenoviruses is that by their very nature they potently stimulate multiple arms of the immune system. Thus, combined tumor killing via oncolysis and inherent immunostimulatory properties in fact make these viruses in situ tumor vaccines. When further engineered to express cytokines, chemokines, tumor-associated antigens, or other immunomodulatory elements, they have been shown in various preclinical models to induce antigen-specific effector and memory responses, resulting both in full therapeutic cures and even induction of life-long tumor immunity. Here, we review the state of the art of oncolytic adenovirus, in the context of their capability to stimulate innate and adaptive arms of the immune system and finally how we can modify these viruses to direct the immune response toward cancer.

Co-transfection gene delivery of dendritic cells induced effective lymph node targeting and anti-tumor vaccination

PURPOSE

Successful genetically engineered Dendritic Cell (DC) can enhance DC's antigen presentation and lymph node migration. The present study aims to genetically engineer a DC using an efficient non-viral gene delivery vector to induce a highly efficient antigen presentation and lymph node targeting in vivo.

METHODS

Spermine-dextran (SD), a cationic polysaccharide vector, was used to prepare a gene delivery system for DC engineering. Transfection efficiency, nuclear trafficking, and safety of the SD/DNA complex were evaluated. A vaccine prepared by engineering DC with SD/gp100, a plasmid encoding melanoma-associated antigen, was injected subcutaneously into mice to evaluate the tumor suppression. The migration of the engineered DCs was also evaluated in vitro and in vivo.

RESULTS

SD/DNA complex has a better transfection behavior in vitro than commercially purchased reagents. The DC vaccine co-transfected with plasmid coding CCR7, a chemokine receptor essential for DC migration, and plasmid coding gp100 displayed superior tumor suppression than that with plasmid coding gp100 alone. Migration assay demonstrated that DC transfected with SD/CCR7 can promote DC migration capacity.

CONCLUSIONS

The study is the first to report the application of nonviral vector SD to co-transfect DC with gp100 and CCR7-coding plasmid to induce both the capacity of antigen presentation and lymph node targeting.

Cytokine-conditioned dendritic cells induce humoral tolerance to protein therapy in mice

A major obstacle in the genetic therapy of inherited metabolic disease is host immune responses to the therapeutic protein. This is best exemplified by inhibitor formation in the protein therapy for hemophilia A. An approach to overcoming this is induction of immunological tolerance to the therapeutic protein. Tolerogenic dendritic cells (DCtols) have been reported to induce tolerance. In addition, cytokines such as interleukin (IL)-10 and transforming growth factor (TGF)-β(1) are known to induce tolerance. To model protein therapy, we used ovalbumin (OVA) as antigen in BALB/c mice and their transgenic derivative, DO11.10 mice. In this study we show that adoptive transfer of antigen-pulsed dendritic cells (DCs) treated with a combination of IL-10 and TGF-β(1) can suppress the antibody response in mice. Adoptive transfer of cytokine-conditioned DCs in preimmunized mice results in reduction of antibody response in the mice. Furthermore, the effect is antigen specific, as the recipient mice were able to mount a potent antibody response to the control antigen. Last, we show that TGF-β(1) and IL-10-conditioned DCs are able to inhibit anti-FVIII antibody responses in FVIII knockout (KO) mice. Analysis of the contribution of IL-10 and TGF-β(1) to the DCtol phenotype shows that IL-10 treatment of DCs is sufficient for inducing OVA-specific tolerance in BALB/c mice, but we observed a requirement for treatment with both human TGF-β(1) and human IL-10 to significantly inhibit anti-FVIII antibody responses in FVIII KO mice. This paper demonstrates that autologous cell therapy for antigen-targeted immune suppression may be developed to facilitate long-term therapy.

Targeted vault nanoparticles engineered with an endosomolytic peptide deliver biomolecules to the cytoplasm

Vault nanoparticles were engineered to enhance their escape from the endosomal compartment by fusing a membrane lytic peptide derived from adenovirus protein VI (pVI) to the N-terminus of the major vault protein to form pVI-vaults. We demonstrate that these pVI-vaults disrupt the endosomal membrane using three different experimental protocols including (1) enhancement of DNA transfection, (2) co-delivery of a cytosolic ribotoxin, and (3) direct visualization by fluorescence. Furthermore, direct targeting of vaults to specific cell surface epidermal growth factor receptors led to enhanced cellular uptake and efficient delivery of vaults to the cytoplasm. This process was monitored with fluorescent vaults, and morphological changes in the endosomal compartment were observed. By combining targeting and endosomal escape into a single recombinant vault, high levels of transfection efficiency were achieved using low numbers of vault particles. These results demonstrate that engineered vaults are effective, efficient, and nontoxic nanoparticles for targeted delivery of biomaterials to the cell cytoplasm.

Calcium gluconate in phosphate buffered saline increases gene delivery with adenovirus type 5

Background

Adenoviruses are attractive vectors for gene therapy because of their stability in vivo and the possibility of production at high titers. Despite exciting preclinical data with various approaches, there are only a few examples of clear efficacy in clinical trials. Effective gene delivery to target cells remains the key variable determining efficacy and thus enhanced transduction methods are important.

Methods/Results

We found that heated serum could enhance adenovirus 5 mediated gene delivery up to twentyfold. A new protein-level interaction was found between fiber knob and serum transthyretin, but this was not responsible for the observed effect. Instead, we found that heating caused the calcium and phosphate present in the serum mix to precipitate, and this was responsible for enhanced gene delivery. This finding could have relevance for designing preclinical experiments with adenoviruses, since calcium and phosphate are present in many solutions. To translate this into an approach potentially testable in patients, we used calcium gluconate in phosphate buffered saline, both of which are clinically approved, to increase adenoviral gene transfer up to 300-fold in vitro. Gene transfer was increased with or without heating and in a manner independent from the coxsackie-adenovirus receptor. In vivo, in mouse studies, gene delivery was increased 2-, 110-, 12- and 13-fold to tumors, lungs, heart and liver and did not result in increased pro-inflammatory cytokine induction. Antitumor efficacy of a replication competent virus was also increased significantly.

Conclusion

In summary, adenoviral gene transfer and antitumor efficacy can be enhanced by calcium gluconate in phosphate buffered saline.

Induction of T cells suppression by dendritic cells transfected with VSIG4 recombinant adenovirus

VSIG4 has been recently described as a B7 family-related protein. The immunotherapeutic potential of dendritic cells (DCs) transfected with VSIG4 recombinant adenovirus has not been characterized. In the present study, DCs were transfected with human VSIG4 (hVSIG4) recombinant adenovirus, a novel costimulatory molecule known to be a potent inhibitor of T cell activation. Transfected DCs were cocultured with allogeneic T cells and proliferation, cytokine production and T cell activation marker expression were assessed. The results showed that T cell proliferation potential, cytokine production and activation marker expression were suppressed after coculture with hVSIG4 recombinant adenovirus-transfected DCs. These findings suggest that DCs transfected with hVSIG4 recombinant adenovirus are capable of inducing allogeneic T cell suppression, which represents an ideal strategy for manipulating the immune response to transplanation or autoimmune diseases.

Vault nanoparticles containing an adenovirus-derived membrane lytic protein facilitate toxin and gene transfer

Nonviral methods of gene delivery possess several advantages over that of viral-based vectors, including having increased safety. However, the ability to achieve effective transport of therapeutic molecules across host cell membranes via nonviral methods remains a significant goal. Cell-derived nanoparticles known as vaults have been proposed as novel candidate transfer vehicles for various foreign molecules. Recombinant vault particles enter cells via macropinocytosis or phagocytosis but lack demonstrable membrane penetrating activity. To explore the feasibility of improving vault penetration into target cells, we incorporated the membrane lytic domain of adenovirus protein VI (pVI) into the interior of recombinant vault particles via fusion to the vault poly(ADP-ribose) polymerase (VPARP) interaction domain. The membrane lytic activity of the pVI domain was retained upon incorporation into vault particles. Moreover, internalization of vault-pVI complexes into murine macrophages promoted co-delivery of a soluble ribotoxin or a cDNA plasmid encoding GFP. These findings indicate that vault particles can be modified to enhance cell transfer of selected biomolecules.

Helios Gene Gun-mediated transfection of the inner ear sensory epithelium

Helios Gene Gun-mediated transfection is a biolistic method for mechanical delivery of exogenous DNA into cells in vitro or in vivo. The technique is based on bombardment of a targeted cellular surface by micron- or submicron-sized DNA-coated gold particles that are accelerated by a pressure pulse of compressed helium gas. The main advantage of Helios Gene Gun-mediated transfections is that it functions well on various cell types, including terminally differentiated cells that are difficult to transfect, such as neurons or inner ear sensory hair cells, and cells in internal cellular layers, such as neurons in organotypic brain slices. The successful delivery of mRNA, siRNA, or DNA of practically any size can be achieved using biolistic transfection. This chapter provides a detailed description and critical evaluation of the methodology used to transfect cDNA expression constructs, including green fluorescent protein (GFP) tagged full-length cDNAs of myosin XVa, whirlin, and beta-actin, into cultured inner ear sensory epithelia using the Bio-Rad Helios Gene Gun.

Using dendritic cell maturation and IL-12 producing capacity as markers of function: a cautionary tale

Effective dendritic cell (DC) function depends on sufficient expression of antigen and costimulatory molecules, and secretion of interleukin (IL)-12. We sought to augment DC stimulatory capacity by optimizing DC phenotype and IL-12 production. DCs, obtained by CD14-selection, were matured using 8 different cytokine cocktails, and expression of costimulatory/major histocompatibility complex molecules and IL-12 production at the end of maturation was assessed. DC stimulatory capacity was determined after pulsing with immunogenic adenoviral CD8 peptide epitopes or after transduction with an Ad5f35-null vector. Resultant T-cell cultures were analyzed using pentamer and interferon-gamma enzyme-linked immunosorbent spot assays. On the basis of DC expression of maturation markers and IL-12 production, we defined prototype "minimal" [tumor necrosis factor-alpha (TNF-alpha), prostaglandin E2], "standard" (IL-1, IL-6, TNF-alpha, prostaglandin E2), and "optimal" (IL-1, IL-6, TNF-alpha, interferon-alpha, CD40 ligand) DC cocktails. Optimal DCs were functionally superior when pulsed with CD8 peptides, but when transduced with Ad5f35, functioned poorly as antigen-presenting cells. We investigated the mechanisms underlying this discrepancy and suggest that prolonged stimulation with potent cytokines (optimal cocktail) in combination with adenoviral transduction alters the kinetics of DC maturation such that the DCs are functionally exhausted by the traditional 48-hour maturation time point. Shortening the DC maturation period posttransduction restored optimal DC stimulatory capacity. Thus, maturation stimuli and viral transduction affects DC phenotype, IL-12 producing capacity, and kinetics of maturation, and all must be considered before designing protocols to generate the optimal DC for cytotoxic T lymphocyte generation.

Factors involved in the maturation of murine dendritic cells transduced with adenoviral vector variants

Adenoviral vector (Ad)-mediated gene transfer is an attractive method for manipulating the immunostimulatory properties of dendritic cells (DCs) for cancer immunotherapy. DCs treated with Ad have phenotype alterations (maturation) that facilitate T cell sensitization. We investigated the mechanisms of DC maturation with Ad transduction. Expression levels of a maturation marker (CD40) on DCs treated with conventional Ad, fiber-modified Ads (AdRGD, AdF35, AdF35DeltaRGD), or a different serotype Ad (Ad35) were correlated with their transduction efficacy. The alphav-integrin directional Ad, AdRGD, exhibited the most potent ability to enhance both foreign gene expression and CD40 expression, and induced secretion of interleukin-12, tumor necrosis factor-alpha, and interferon-alpha in DCs. The presence of a foreign gene expression cassette in AdRGD was not necessary for DC maturation. Maturation of DCs treated with AdRGD was suppressed by destruction of the Ad genome, inhibition of endocytosis, or endosome acidification, whereas proteasome inhibition increased CD40 expression levels on DCs. Moreover, inhibition of alphav-integrin signal transduction and blockade of cytokine secretion affected the maturation of DCs treated with AdRGD only slightly or not at all, respectively. Thus, our data provide evidence that Ad-induced DC maturation is due to Ad invasion of the DCs, followed by nuclear transport of the Ad genome, and not to the expression of foreign genes.