MHC class I and class II presentation of tumor antigen in retrovirally and adenovirally transduced dendritic cells

Revolutionizing cancer treatment: The power of dendritic cell-based vaccines in immunotherapy

In the modern time, cancer immunotherapies have increasingly become vital treatment options, joining long-established methods like surgery, chemotherapy, and radiotherapy treatment. Central to this emerging approach are dendritic cells (DCs), which boast a remarkable ability for antigen presentation. This ability is being leveraged to modulate T and B cell immunity, offering a groundbreaking strategy for tackling cancer. However, the percentage of patients experiencing meaningful benefits from this treatment remains relatively low, underscoring the ongoing necessity for further research and development in this field. This review offers a comprehensive analysis of the present-day progress in dendritic cell (DC)-based vaccines and recent efforts to enhance their efficacy. We explore the intricacies of DC function, from antigen capture to T cell stimulation, and discuss the outcomes of both preclinical and clinical trials across various cancer types. While the results are promising, the real-world application of DC-based vaccines is still nascent, posing multiple challenges that need to be overcome. These obstacles include optimizing the methods for DC generation and antigen loading, overcoming the immunosuppressive nature of the tumor microenvironment, and enhancing specificities of the immunologic response through personalized vaccines. The review concludes by emphasizing prospective opportunities for future research and emphasizing the critical need for extensive clinical trials. These trials are essential to validate the effectivity of DC-based vaccines and solidify their role in the broader spectrum of cancer immunotherapy options.

Molecular Mechanism of VSV-Vectored ASFV Vaccine Activating Immune Response in DCs

The vesicular stomatitis virus (VSV)-vectored African swine fever virus (ASFV) vaccine can induce efficient immune response, but the potential mechanism remains unsolved. In order to investigate the efficacy of recombinant viruses (VSV-p35, VSV-p72)-mediated dendritic cells (DCs) maturation and the mechanism of inducing T-cell immune response, the functional effects of recombinant viruses on DC activation and target antigens presentation were explored in this study. The results showed that surface-marked molecules (CD80, CD86, CD40, and MHC-II) and secreted cytokines (IL-4, TNF-α, IFN-γ) were highly expressed in the recombinant virus-infected DCs. In addition, the co-culture results of recombinant virus-treated DCs with naive T cells showed that the Th1- and Th17-type responses were effectively activated. Taken together, the study indicated that the VSV-vectored ASFV vaccine activated the maturation of DCs and the Th1- and Th17-type immune response, which provided a theoretical basis for the development of novel ASF vaccines.

Immunologic Aspects of Dyslipidemia: a Critical Regulator of Adaptive Immunity and Immune Disorders

Dyslipidemia is a major cause of cardiovascular diseases which represent a leading cause of death in humans. Diverse immune cells are known to be involved in the pathogenesis of cardiovascular diseases such as atherosclerosis. Conversely, dyslipidemia is known to be tightly associated with immune disorders in humans, as evidenced by a higher incidence of atherosclerosis in patients with autoimmune diseases including psoriasis, rheumatoid arthritis, and systemic lupus erythematosus. Given that the dyslipidemia-related autoimmune diseases are caused by autoreactive T cells and B cells, dyslipidemia seems to directly or indirectly regulate the adaptive immunity. Indeed, accumulating evidence has unveiled that proatherogenic factors can impact the differentiation and function of CD4⁺ T cells, CD8⁺ T cells, and B cells. This review discusses an updated overview on the regulation of adaptive immunity by dyslipidemia and proposes a potential therapeutic strategy for immune disorders by targeting lipid metabolism.

LC3-Associated Phagocytosis (LAP): A Potentially Influential Mediator of Efferocytosis-Related Tumor Progression and Aggressiveness

One aim of cancer therapies is to induce apoptosis of tumor cells. Efficient removal of the apoptotic cells requires coordinated efforts between the processes of efferocytosis and LC3-associated phagocytosis (LAP). However, this activity has also been shown to produce anti-inflammatory and immunosuppressive signals that can be utilized by live tumor cells to evade immune defense mechanisms, resulting in tumor progression and aggressiveness. In the absence of LAP, mice exhibit suppressed tumor growth during efferocytosis, while LAP-sufficient mice show enhanced tumor progression. Little is known about how LAP or its regulators directly affect efferocytosis, tumor growth and treatment responses, and identifying the mechanisms involved has the potential to lead to the discovery of novel approaches to target cancer cells. Also incompletely understood is the direct effect of apoptotic cancer cells on LAP. This is particularly important as induction of apoptosis by current cytotoxic cancer therapies can potentially stimulate LAP following efferocytosis. Herein, we highlight the current understanding of the role of LAP and its relationship with efferocytosis in the tumor microenvironment with a view to presenting novel therapeutic strategies.

The immunoregulatory function of polyphenols: implications in cancer immunity

Polyphenols have demonstrated several potential biological activities, notably antitumoral activity dependent on immune function. In the present review, we describe studies that investigated antitumor immune responses influenced by polyphenols and the mechanisms by which polyphenols improve the immune response. We also discuss the limitations in related areas, especially unexplored areas of research, and next steps required to develop a therapeutic approach utilizing polyphenols in oncology.

CD40-targeted adenoviral cancer vaccines: the long and winding road to the clinic

The ability of dendritic cells (DCs) to orchestrate innate and adaptive immune responses has been exploited to develop potent anti-cancer immunotherapies. Recent clinical trials exploring the efficacy of ex vivo modified autologous DC-based vaccines have reported some promising results. However, in vitro generation of autologous DCs for clinical administration, their loading with tumor associated antigens (TAAs) and their activation, is laborious and expensive, and, as a result of inter-individual variability in the personalized vaccines, remains poorly standardized. An attractive alternative approach is to load resident DCs in vivo by targeted delivery of TAAs, using viral vectors and activating them simultaneously. To this end, we have constructed genetically-modified adenoviral (Ad) vectors and bispecific adaptor molecules to retarget Ad vectors encoding TAAs to the CD40 receptor on DCs. Pre-clinical human and murine studies conducted so far have clearly demonstrated the suitability of a 'two-component' (i.e. Ad and adaptor molecule) configuration for targeted modification of DCs in vivo for cancer immunotherapy. This review summarizes recent progress in the development of CD40-targeted Ad-based cancer vaccines and highlights pre-clinical issues in the clinical translation of this approach.

PLGA nanoparticle-mediated delivery of tumor antigenic peptides elicits effective immune responses

The peptide vaccine clinical trials encountered limited success because of difficulties associated with stability and delivery, resulting in inefficient antigen presentation and low response rates in patients with cancer. The purpose of this study was to develop a novel delivery approach for tumor antigenic peptides in order to elicit enhanced immune responses using poly(DL-lactide-co-glycolide) nanoparticles (PLGA-NPs) encapsulating tumor antigenic peptides. PLGA-NPs were made using the double emulsion-solvent evaporation method. Artificial antigen-presenting cells were generated by human dendritic cells (DCs) loaded with PLGA-NPs encapsulating tumor antigenic peptide(s). The efficiency of the antigen presentation was measured by interferon-γ ELISpot assay (Vector Laboratories, Burlingame, CA). Antigen-specific cytotoxic T lymphocytes (CTLs) were generated and evaluated by CytoTox 96(®) Non-Radioactive Cytotoxicity Assay (Promega, Fitchburg, WI). The efficiency of the peptide delivery was compared between the methods of emulsification in incomplete Freund's adjuvant and encapsulation in PLGA-NPs. Our results showed that most of the PLGA-NPs were from 150 nm to 500 nm in diameter, and were negatively charged at pH 7.4 with a mean zeta potential of -15.53 ± 0.71 mV; the PLGA-NPs could be colocalized in human DCs in 30 minutes of incubation. Human DCs loaded with PLGA-NPs encapsulating peptide induced significantly stronger CTL cytotoxicity than those pulsed with free peptide, while human DCs loaded with PLGA-NPs encapsulating a three-peptide cocktail induced a significantly greater CTL response than those encapsulating a two-peptide cocktail. Most importantly, the peptide dose encapsulated in PLGA-NPs was 63 times less than that emulsified in incomplete Freund's adjuvant, but it induced a more powerful CTL response in vivo. These results demonstrate that the delivery of peptides encapsulated in PLGA-NPs is a promising approach to induce effective antitumor CTL responses in vivo.

Chapter six--Adenovirus-based immunotherapy of cancer: promises to keep

Progress in vector design and an increased knowledge of mechanisms underlying tumor-induced immune suppression have led to a new and promising generation of Adenovirus (Ad)-based immunotherapies, which are discussed in this review. As vaccine vehicles Ad vectors (AdVs) have been clinically evaluated and proven safe, but a major limitation of the commonly used Ad5 serotype is neutralization by preexistent or rapidly induced immune responses. Genetic modifications in the Ad capsid can reduce intrinsic immunogenicity and facilitate escape from antibody-mediated neutralization. Further modification of the Ad hexon and fiber allows for liver and scavenger detargeting and selective targeting of, for example, dendritic cells. These next-generation Ad vaccines with enhanced efficacy are now becoming available for testing as tumor vaccines. In addition, AdVs encoding immune-modulating products may be used to convert the tumor microenvironment from immune-suppressive and proinvasive to proinflammatory, thus facilitating cell-mediated effector functions that can keep tumor growth and invasion in check. Oncolytic AdVs, that selectively replicate in tumor cells and induce an immunogenic form of cell death, can also be armed with immune-activating transgenes to amplify primed antitumor immune responses. These novel immunotherapy strategies, employing highly efficacious AdVs in optimized configurations, show great promise and warrant clinical exploration.

Potent antitumor immunity generated by a CD40-targeted adenoviral vaccine

In situ delivery of tumor-associated antigen (TAA) genes into dendritic cells (DC) has great potential as a generally applicable tumor vaccination approach. Although adenoviruses (Ad) are an attractive vaccine vehicle in this regard, Ad-mediated transduction of DCs is hampered by the lack of expression of the Ad receptor CAR on the DC surface. DC activation also requires interaction of CD40 with its ligand CD40L to generate protective T-cell-mediated tumor immunity. Therefore, to create a strategy to target Ads to DCs in vivo, we constructed a bispecific adaptor molecule with the CAR ectodomain linked to the CD40L extracellular domain via a trimerization motif (CFm40L). By targeting Ad to CD40 with the use of CFm40L, we enhanced both transduction and maturation of cultured bone marrow-derived DCs. Moreover, we improved transduction efficiency of DCs in lymph node and splenic cell suspensions in vitro and in skin and vaccination site-draining lymph nodes in vivo. Furthermore, CD40 targeting improved the induction of specific CD8(+) T cells along with therapeutic efficacy in a mouse model of melanoma. Taken together, our findings support the use of CD40-targeted Ad vectors encoding full-length TAA for in vivo targeting of DCs and high-efficacy induction of antitumor immunity.

IL-15 and type I interferon are required for activation of tumoricidal NK cells by virus-infected dendritic cells

There is increasing evidence that natural killer (NK) cells play an important role in antitumor immunity following dendritic cell (DC) vaccination. Little is known, however, about the optimal stimulation of DCs that favors NK activation in tumor-bearing hosts. In this study, we demonstrate that treatment with toll-like receptor (TLR) ligands and infection with a mutant vesicular stomatitis virus (VSV-ΔM51) both induced DC maturation. Further, inoculation of these DCs led to robust NK-mediated protection against tumor challenge. Strikingly, only VSV-ΔM51-infected DCs were capable of suppressing the growth of established tumors, suggesting that additional signals provided by viral infection may be required to activate tumoricidal NK cells in tumor-bearing hosts. VSV-ΔM51 infection of DCs induced greater type I interferon (IFN I) production than TLR ligand treatment, and disruption of the IFN I pathway in DCs eliminated their ability to induce NK activation and tumor protection. However, further studies indicated that IFN I alone was not sufficient to activate NK cells, especially in the presence of a tumor, and DC-derived IL-15 was additionally required for tumoricidal NK activation. These results suggest that induction of IFN I by VSV-ΔM51 allows DCs to overcome tumor-associated immunosuppression and facilitate IL-15-mediated priming of tumoricidal NK cells. Thus, the mode of DC maturation should be carefully considered when designing DC-based cancer immunotherapies.

Deoxypodophyllotoxin Induces a Th1 Response and Enhances the Antitumor Efficacy of a Dendritic Cell-based Vaccine

Background

Dendritic cell (DC)-based vaccines are currently being evaluated as a novel strategy for tumor vaccination and immunotherapy. However, inducing long-term regression in established tumor-implanted mice is difficult. Here, we show that deoxypohophyllotoxin (DPT) induces maturation and activation of bone marrow-derived DCs via Toll-like receptor (TLR) 4 activation of MAPK and NF-κB.

Methods

The phenotypic and functional maturation of DPT-treated DCs was assessed by flow cytometric analysis and cytokine production, respectively. DPT-treated DCs was also used for mixed leukocyte reaction to evaluate T cell-priming capacity and for tumor regression against melanoma.

Results

DPT promoted the activation of CD8⁺ T cells and the Th1 immune response by inducing IL-12 production in DCs. In a B16F10 melanoma-implanted mouse model, we demonstrated that DPT-treated DCs (DPT-DCs) enhance immune priming and regression of an established tumor in vivo. Furthermore, migration of DPT-DCs to the draining lymph nodes was induced via CCR7 upregulation. Mice that received DPT-DCs displayed enhanced antitumor therapeutic efficacy, which was associated with increased IFN-γ production and induction of cytotoxic T lymphocyte activity.

Conclusion

These findings strongly suggest that the adjuvant effect of DPT in DC vaccination is associated with the polarization of T effector cells toward a Th1 phenotype and provides a potential therapeutic antitumor immunity.

Dendritic cells transfected with lentiviral vector-encoding human granulocyte-macrophage colony-stimulating factor augment anti-tumour T-cell response in vitro

Dendritic cells (DC) are professional antigen-presenting cells that can actively taken up and present tumour-derived proteins to induce a tumour-specific immune response. Granulocyte-macrophage colony-stimulating factor (GM-CSF) plays a pivotal role in the generation, sensitization, maturation and survival of DC. We charged the peripheral blood monocyte cell-derived DC with tumour lysate, and then transfected the DC with lentiviral vector-encoding human GM-CSF (hGM-CSF). The antigen-presenting capacity of the hGM-CSF-transfected DC was tested by means of the mixed lymphocyte reaction and cytotoxic T-lymphocyte assay using wild-type DC as the control. The Lenti-hGM-CSF-transfected DC was able to stimulate the proliferation of naive allogeneic T lymphocytes and to generate tumour-specific cytotoxic T lymphocytes more efficiently than the wild-type DC. This data indicates that Lenti-hGM-CSF-transfected DC could potentially be used as an effective clinical approach for cancer immunotherapy.

Recombinant vesicular stomatitis virus transduction of dendritic cells enhances their ability to prime innate and adaptive antitumor immunity

Dendritic cell (DC)-based vaccines are a promising strategy for tumor immunotherapy due to their ability to activate both antigen-specific T-cell immunity and innate immune effector components, including natural killer (NK) cells. However, the optimal mode of antigen delivery and DC activation remains to be determined. Using M protein mutant vesicular stomatitis virus (DeltaM51-VSV) as a gene-delivery vector, we demonstrate that a high level of transgene expression could be achieved in approximately 70% of DCs without affecting cell viability. Furthermore, DeltaM51-VSV infection activated DCs to produce proinflammatory cytokines (interleukin-12, tumor necrosis factor-alpha, and interferon (IFN)alpha/beta), and to display a mature phenotype (CD40(high)CD86(high) major histocompatibility complex (MHC II)(high)). When delivered to mice bearing 10-day-old lung metastatic tumors, DCs infected with DeltaM51-VSV encoding a tumor-associated antigen mediated significant control of tumor growth by engaging both NK and CD8(+) T cells. Importantly, depletion of NK cells completely abrogated tumor destruction, indicating that NK cells play a critical role for this DC vaccine-induced therapeutic outcome. Our findings identify DeltaM51-VSV as both an efficient gene-delivery vector and a maturation agent allowing DC vaccines to overcome immunosuppression in the tumor-bearing host.

Dendritic cells transduced with lentiviral-mediated RelB-specific ShRNAs inhibit the development of experimental autoimmune myasthenia gravis

Dendritic cells (DC) are professional APC that are able to modulate immune response in either a positive or negative manner depending upon their lineage and state of maturation. RelB is a NF-kappaB family member which plays a key role in the differentiation and maturation of DC. In this study, we constructed lentiviral vector expressing RelB-specific short hairpin RNAs (ShRNAs) that efficiently silenced the RelB gene in bone marrow-derived dendritic cells (BMDCs). These RelB-silenced BMDCs were maturation resistant and could functionally decrease antigen-specific T cells proliferation. We tested the therapeutic effect of RelB-silenced BMDCs in C57BL/6 mice with experimental autoimmune myasthenia gravis (EAMG). Injection i.v. with RelB-silenced BMDCs plused with Torpedo acetylcholine receptor (TAChR) dominant peptide Talpha(146-162) on days 3, 33, and 63 after first immunization decreased the incidence and severity of clinical EAMG with suppressed IFN-gamma production and increased IL-10 and IL-4 production in vitro and in vivo, and also leads to a decreased serum anti-AChR IgG, IgG1, IgG2b Ab levels. Furthermore, RelB-silenced BMDCs promoted regulatory T cell profiles as indicated by a marked increase of FoxP3 in splenocyte. Our data suggested that lentiviral-mediated RNAi targeting RelB was effective methods to inhibit the maturation of BMDCs, thus possess therapeutic potential to prevent autoimmune disorders such as EAMG or human MG.

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.

Tumor-specific dendritic cells generated by genetic redirection of Toll-like receptor signaling against the tumor-associated antigen, erbB2

Dendritic cells (DC) perform an important role in the initiation of the immune response through the local secretion of inflammatory mediators within diseased tissue in response to Toll-like receptor (TLR) ligation. However, DC vaccine strategies fail to make use of this capability against cancer. To harness the TLR response capability of DC against cancer, we tested a series of recombinant genes for their ability to redirect DC function specifically against a tumor-associated antigen. Each gene encoded a cell surface chimeric protein made up of extracellular single-chain immunoglobulin anti-erbB2 linked to an intracellular TLR-signaling component composed of either myeloid differentiation factor 88, interleukin-1 receptor-associated kinase-1 (IRAK-1) or the cytoplasmic domain of TLR4. Each gene was expressed in the DC line, JAWS II, to a similar degree following retroviral transduction. However, only the chimera containing IRAK-1 was able to mediate interleukin-12 and tumor necrosis factor-alpha secretion. Since TLR engagement can also activate DC and enhance their ability to stimulate T cells, we ligated the chimeric anti-erbB2-IRAK-1 receptor and determined the effect on the stimulation of T cells. We found that JAWS II cells triggered through chimeric anti-erbB2-IRAK-1 displayed an enhanced ability to stimulate ovalbumin-specific OT-II CD4(+) T cells. This first description of the generation of tumor-reactive DC may lead to the development of new cell-based vaccines that can act at both the tumor site to induce danger and at the lymph node to stimulate a specific T-cell response.

An effective cancer vaccine modality: lentiviral modification of dendritic cells expressing multiple cancer-specific antigens

Viral modification of dendritic cells (DCs) may deliver a "danger signal" critical to the hypo-reactive DCs in cancer patients. Using three highly differentially expressed hepatoma tumor-associated antigens (TAAs): stem cell antigen-2 (Sca-2), glycoprotein 38 (GP38) and cellular retinoic acid binding protein 1 (RABP1), we explored the therapeutic potential of the DCs modified with lentiviral vectors (LVs). Preventive and therapeutic injection of the LV-TAA-DC vaccine into tumor-bearing mice elicited a strong anti-tumor response and extended survival, which was associated with tumor-specific interferon-gamma and cytotoxic T cell responses. In vivo elimination of the LV-TAA-DCs by a co-expressed thymidine kinase suicide gene abrogated the therapeutic effect. The modification of DCs with LVs encoding multiple TAAs offers a great opportunity in cancer immunotherapy.

Lentivirus vector-mediated expression of tumor-associated epitopes by human antigen presenting cells

Directing the human immune system to recognize and eliminate tumor cells is the ultimate goal of cancer immunotherapy. Vaccinating patients with autologous antigen presenting cells (APC) expressing tumor-associated antigens (TAA) represents a promising approach for activating tumor-reactive T cells in vivo. In addition, APC expressing TAA provide a means of generating tumor-specific T cells in vitro, for therapeutic and diagnostic applications. Lentiviral vectors are attractive vehicles for introducing TAA-encoding genes into APC. In this study, lentiviral vectors expressing the reporter gene GFP or the melanoma-associated antigen tyrosinase were used to transduce three different kinds of human APC: monocyte-derived dendritic cells (DC), CD40L-activated B lymphocytes, and Epstein Barr virus (EBV)-transformed B lymphocytes. Using optimized transduction conditions for each cell type, tyrosinase was expressed at levels sufficient to stimulate antigen-specific major histocompatibility complex (MHC) class I-restricted T cells from melanoma patients. While transduced EBV-B cells demonstrated the highest level of transgene expression, optimal T-cell recognition was achieved with transduced DC. Substituting the CAG promoter for PGK in lentiviral constructs enhanced transgene expression in DC and EBV-B cells, amplifying T cell recognition. Lentiviruses inducing sustained transgene expression with relatively low cellular toxicity and background viral gene expression may be ideal vectors for immunotherapeutic applications.

Dendritic cells transduced with gp100 gene by RGD fiber-mutant adenovirus vectors are highly efficacious in generating anti-B16BL6 melanoma immunity in mice

Dendritic cells (DCs) are the most potent professional antigen-presenting cells for the initiation of antigen-specific immune responses, and antigen-loaded DCs have been regarded as promising vaccines in cancer immunotherapy. We previously demonstrated that RGD fiber-mutant adenovirus vector (AdRGD) could attain highly efficient gene transduction into human and murine DCs. The aim of the present study is to demonstrate the predominance of ex vivo genetic DC manipulation using AdRGD in improving the efficacy of DC-based immunotherapy targeting gp100, a melanoma-associated antigen (MAA). Vaccination with murine bone marrow-derived DCs transduced with AdRGD encoding gp100 (AdRGD-gp100/mBM-DCs) dramatically improved resistance to B16BL6 melanoma challenge and pulmonary metastasis as compared with immunization with conventional Ad-gp100-transduced mBM-DCs. The improvement in antimelanoma effects upon immunization with AdRGD-gp100/mBM-DCs correlated with enhanced cytotoxic activities of natural killer (NK) cells and B16BL6-specific cytotoxic T lymphocytes (CTLs). Furthermore, in vivo depletion analysis demonstrated that CD8(+) CTLs and NK cells were the predominant effector cells responsible for the anti-B16BL6 immunity induced by vaccination with AdRGD-gp100/mBM-DCs, and that helper function of CD4(+) T cells was necessary for sufficiently eliciting effector activity. These findings clearly revealed that highly efficient MAA gene transduction to DCs by AdRGD could greatly improve the efficacy of DC-based immunotherapy against melanoma.