Type-1 polarized dendritic cells primed for high IL-12 production show enhanced activity as cancer vaccines

Nicotine is an Immunosuppressant: Implications for Women's Health and Disease

A plethora of evidence supports that nicotine, the primary alkaloid in tobacco products that is generally accepted for maintaining use, is immunoregulatory and may function as an immunosuppressant. Women have unique experiences with use of nicotine-containing products and also undergo significant reproductive transitions throughout their lifespan which may be impacted by nicotine use. Within the extant literature, there is conflicting evidence that nicotine may confer beneficial health effects in specific disease states (e.g., in ulcerative colitis). Use prevalence of nicotine-containing products is exceptionally high in individuals presenting with some comorbid disease states that impact immune system health and can be a risk factor for the development of diseases which disproportionately impact women; however, the mechanisms underlying these relationships are largely unclear. Further, little is known regarding the impacts of nicotine's immunosuppressive effects on women's health during the menopausal transition, which is arguably an inflammatory event characterized by a pro-inflammatory peri-menopause period. Given that post-menopausal women are at a higher risk than men for the development of neurodegenerative diseases such as Alzheimer's disease and are also more vulnerable to negative health effects associated with diseases such as HIV-1 infection, it is important to understand how use of nicotine-containing products may impact the immune milieu in women. In this review, we define instances in which nicotine use confers immunosuppressive, anti-inflammatory, or pro-inflammatory effects in the context of comorbid disease states, and focus on how nicotine impacts neuroimmune signaling to maintain use. We posit that regardless of potential health benefits, nicotine use cessation should be a priority in the clinical care of women. The synthesis of this review demonstrates the importance of systematically defining the relationships between volitional nicotine use, immune system function, and comorbid disease states in women to better understand how nicotine impacts women's health and disease.

Reviewing the significance of dendritic cell vaccines in interrupting breast cancer development

Breast cancer is a heterogeneous disease and is the most prevalent cancer in women. According to the U.S breast cancer statistics, about 1 in every 8 women develop an invasive form of breast cancer during their lifetime. Immunotherapy has been a significant advancement in the treatment of cancer with multiple studies reporting favourable patient outcomes by modulating the immune response to cancer cells. Here, we review the significance of dendritic cell vaccines in treating breast cancer patients. We discuss the involvement of dendritic cells and oncodrivers in breast tumorigenesis, highlighting the rationale for targeting oncodrivers and neoantigens using dendritic cell vaccine therapy. We review different dendritic cell subsets and maturation states previously used to develop vaccines and suggest the use of DC vaccines for breast cancer prevention. Further, we highlight that the intratumoral delivery of type 1 dendritic cell vaccines in breast cancer patients activates tumor antigen-specific CD4+ T helper cell type 1 (Th1) cells, promoting an anti-tumorigenic immune response while concurrently blocking pro-tumorigenic responses. In summary, this review provides an overview of the current state of dendritic cell vaccines in breast cancer highlighting the challenges and considerations necessary for an efficient dendritic cell vaccine design in interrupting breast cancer development.

Plantago asiatica L. polysaccharides: Physiochemical properties, structural characteristics, biological activity and application prospects: A review

Plantago asiatica L. (PAL), a traditional herb, has been used in East Asia for thousands of years. In recent years, polysaccharides extracted from PAL have garnered increased attention due to their outstanding pharmacological and biological properties. Previous research has established that PAL-derived polysaccharides exhibit antioxidant, anti-inflammatory, antidiabetic, antitumor, antimicrobial, immune-regulatory, intestinal health-promoting, antiviral, and other effects. Nevertheless, a comprehensive summary of the research related to Plantago asiatica L. polysaccharides (PALP) has not been reported to date. In this paper, we review the methods for isolation and purification, physiochemical properties, structural features, and biological activities of PALP. To provide a foundation for research and application in the fields of medicine and food, this review also outlines the future development prospects of plantain polysaccharides.

Advancements in dendritic cell vaccination: enhancing efficacy and optimizing combinatorial strategies for the treatment of glioblastoma

Glioblastomas (GBM) are highly invasive, malignant primary brain tumors. The overall prognosis is poor, and management of GBMs remains a formidable challenge, necessitating novel therapeutic strategies such as dendritic cell vaccinations (DCVs). While many early clinical trials demonstrate an induction of an antitumoral immune response, outcomes are mixed and dependent on numerous factors that vary between trials. Optimization of DCVs is essential; the selection of GBM-specific antigens and the utilization of 18F-fludeoxyglucose Positron Emission Tomography (FDG-PET) may add significant value and ultimately improve outcomes for patients undergoing treatment for glioblastoma. This review provides an overview of the mechanism of DCV, assesses previous clinical trials, and discusses future strategies for the integration of DCV into glioblastoma treatment protocols. To conclude, the review discusses challenges associated with the use of DCVs and highlights the potential of integrating DCV with standard therapies.

Endogenous/Exogenous Nanovaccines Synergistically Enhance Dendritic Cell-Mediated Tumor Immunotherapy

Traditional dendritic cell (DC)-mediated immunotherapy is usually suppressed by weak immunogenicity in tumors and generally leads to unsatisfactory outcomes. Synergistic exogenous/endogenous immunogenic activation can provide an alternative strategy for evoking a robust immune response by promoting DC activation. Herein, Ti3 C2 MXene-based nanoplatforms (termed MXP) are prepared with high-efficiency near-infrared photothermal conversion and immunocompetent loading capacity to form endogenous/exogenous nanovaccines. Specifically, the immunogenic cell death of tumor cells induced by the photothermal effects of the MXP can generate endogenous danger signals and antigens release to boost vaccination for DC maturation and antigen cross-presentation. In addition, MXP can deliver model antigen ovalbumin (OVA) and agonists (CpG-ODN) as an exogenous nanovaccine (MXP@OC), which further enhances DC activation. Importantly, the synergistic strategy of photothermal therapy and DC-mediated immunotherapy by MXP significantly eradicates tumors and enhances adaptive immunity. Hence, the present work provides a two-pronged strategy for improving immunogenicity and killing tumor cells to achieve a favorable outcome in tumor patients.

Biomaterials Facilitating Dendritic Cell-Mediated Cancer Immunotherapy

Dendritic cell (DC)-based cancer immunotherapy has exhibited remarkable clinical prospects because DCs play a central role in initiating and regulating adaptive immune responses. However, the application of traditional DC-mediated immunotherapy is limited due to insufficient antigen delivery, inadequate antigen presentation, and high levels of immunosuppression. To address these challenges, engineered biomaterials have been exploited to enhance DC-mediated immunotherapeutic effects. In this review, vital principal components that can enhance DC-mediated immunotherapeutic effects are first introduced. The parameters considered in the rational design of biomaterials, including targeting modifications, size, shape, surface, and mechanical properties, which can affect biomaterial optimization of DC functions, are further summarized. Moreover, recent applications of various engineered biomaterials in the field of DC-mediated immunotherapy are reviewed, including those serve as immune component delivery platforms, remodel the tumor microenvironment, and synergistically enhance the effects of other antitumor therapies. Overall, the present review comprehensively and systematically summarizes biomaterials related to the promotion of DC functions; and specifically focuses on the recent advances in biomaterial designs for DC activation to eradicate tumors. The challenges and opportunities of treatment strategies designed to amplify DCs via the application of biomaterials are discussed with the aim of inspiring the clinical translation of future DC-mediated cancer immunotherapies.

Remodeling Tumor-Associated Neutrophils to Enhance Dendritic Cell-Based HCC Neoantigen Nano-Vaccine Efficiency

Hepatocellular carcinoma (HCC) commonly emerges in an immunologically "cold" state, thereafter protects it away from cytolytic attack by tumor-infiltrating lymphocytes, resulting in poor response to immunotherapy. Herein, an acidic/photo-sensitive dendritic cell (DCs)-based neoantigen nano-vaccine has been explored to convert tumor immune "cold" state into "hot", and remodel tumor-associated neutrophils to potentiate anticancer immune response for enhancing immunotherapy efficiency. The nano-vaccine is constructed by SiPCCl₂ -hybridized mesoporous silica with coordination of Fe(III)-captopril, and coating with exfoliated membrane of matured DCs by H22-specific neoantigen stimulation. The nano-vaccines actively target H22 tumors and induce immunological cell death to boost tumor-associated antigen release by the generation of excess ¹ O₂ through photodynamic therapy, which act as in situ tumor vaccination to strengthen antitumor T-cell response against primary H22 tumor growth. Interestingly, the nano-vaccines are also home to lymph nodes to directly induce the activation and proliferation of neoantigen-specific T cells to suppress the primary/distal tumor growth. Moreover, the acidic-triggered captopril release in tumor microenvironment can polarize the protumoral N2 phenotype neutrophils to antitumor N1 phenotype for improving the immune effects to achieve complete tumor regression (83%) in H22-bearing mice and prolong the survival time. This work provides an alternative approach for developing novel HCC immunotherapy strategies.

Comparison of four methods of colon cancer cell lysates preparation for ex vivo maturation of dendritic cells

Background and purpose:

One of the most effective methods for the development of dendritic cell (DC)-based cancer immunotherapy is ex vivo pulsing of DCs with tumor cell lysates (TCLs). However, antitumor immune responses of DCs are significantly influenced by how TCLs were prepared. Here, we compared four strategies of TCL preparation derived from colon cancer cells, HT-29, for ex vivo maturation of DCs.

Experimental approach:

Peripheral blood monocytes were isolated from healthy volunteers and incubated with granulocyte macrophage colony-stimulating factor and interleukin (IL)-4 to differentiate into DCs in 10 days. Morphological properties, phenotype characteristics (i.e. CD83 and CD86), and cytokine production (i.e. IL-10 and interferon gamma) of DCs loaded with four different TCLs (i.e. freeze-thaw, hypochlorous acid (HOCl), hyperthermia, and UV irradiation) were evaluated.

Findings/Results:

HOCl preparations led to the generation of DCs with higher surface expression of maturation biomarkers (particularly CD83), while UV preparations resulted in DCs with lower levels of surface biomarkers compared to freeze-thawed preparations. The supernatant of DCs pulsed with HOCl preparation showed significantly higher levels of interferon gamma and lower levels of IL-10 compared with the other groups.

Conclusion and implications:

Our results suggest that pulsing DCs with HOCl preparation may be superior to other TCLs preparation strategies, possibly due to induction of rapid necrotic cell death.

Polymorphisms of IL-4 and IL-4R are associated to some demographic characteristics of differentiated thyroid cancer patients but are not determinants of risk in the Brazilian population

BACKGROUND

IL-4 is known to present abnormal expression in thyroid tumors and SNPs in the IL-4 and its receptor IL-4R genes are associated to risk and mortality of various types of cancer.

METHODS

In order to evaluate their role in differentiated thyroid cancer (DTC), we investigated genetic frequencies of two IL-4 promoter SNPs (rs2070874 C>T, rs2243250 C>T) and four non-synonymous SNPs of the IL-4R gene (rs1805010 A>G, rs1805012 C>T, rs1805013 C>T, rs1801275 A>G) in 300 DTC patients matched to 300 controls. All patients were managed according to current guidelines and followed-up for a period of 12-252 months (69.20 ± 52.70 months).

RESULTS

Although none of the six investigated SNPs showed association with risk of DTC, rs1805010 was associated with age of diagnosis and the SNPs rs1805012 and rs1801275 were associated to gender. Further, in-silico analysis showed that all these three SNPs were able to cause decreased stability of the protein. We were not able to demonstrate any other association to clinical features of aggressiveness or to patients' prognosis.

CONCLUSIONS

These findings indicate that although genetic variants in IL-4 and IL-4R do not influence the risk or outcome of DTC patients, their influence on the behavior of thyroid tumors deserves further investigation.

Phase II Trial of Adjuvant Dendritic Cell Vaccine in Combination with Celecoxib, Interferon-α, and Rintatolimod in Patients Undergoing Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy for Peritoneal Metastases

BACKGROUND

Peritoneal metastases portend poor prognosis in the setting of standard chemotherapy. Cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (CRS/HIPEC) improves outcomes, but relapse is common. We report a phase II trial evaluating the safety and efficacy of adjuvant αDC1 vaccination with chemokine modulation (CKM) after CRS/HIPEC.

METHODS

Patients undergoing CRS/HIPEC for appendiceal cancer, colorectal cancer, or peritoneal mesothelioma were enrolled. In addition to standard adjuvant chemotherapy, patients received intranodal and intradermal injections of autologous tumor-loaded αDC1 vaccine. After each vaccine booster, patients received CKM over 4 days, consisting of celecoxib, interferon (IFN)-α, and rintatolimod.

RESULTS

Forty-six patients underwent CRS/HIPEC followed by αDC1 treatment, including 24 appendiceal primaries, 20 colorectal, and 2 mesotheliomas. DC maturation was successful, with 97% expressing HLA-DR and CD86. Tumor cell recovery from peritoneal tumors was challenging, resulting in only 17% of patients receiving the target dose of αDC1. The αDC1 and CKM regimen was well tolerated. CKM successfully modulated serum inflammatory cytokine and chemokine levels. Median progression-free survival (PFS) for appendiceal primaries was 50.4, 34.2, and 8.9 months for grade 1, 2, and 3 tumors, respectively, while median PFS for colorectal cancer was 20.5 and 8.9 months for moderately and poorly differentiated tumors, respectively.

CONCLUSIONS

Adjuvant autologous tumor antigen-loaded αDC1 vaccine and CKM is well tolerated. The mucinous nature of peritoneal metastases limits the feasibility of obtaining adequate autologous tumor cells. The improvement in median PFS did not meet our predefined thresholds, leading us to conclude that αDC1 vaccination is not appropriate for patients undergoing CRS/HIPEC for peritoneal metastases.

Overexpression of Murine Rnaset2 in a Colon Syngeneic Mouse Carcinoma Model Leads to Rebalance of Intra-Tumor M1/M2 Macrophage Ratio, Activation of T Cells, Delayed Tumor Growth, and Rejection

Human RNASET2 acts as a powerful oncosuppressor protein in in vivo xenograft-based murine models of human cancer. Secretion of RNASET2 in the tumor microenvironment seems involved in tumor suppression, following recruitment of M1-polarized macrophages. Here, we report a murine Rnaset2-based syngeneic in vivo assay. BALB/c mice were injected with parental, empty vector-transfected or murine Rnaset2-overexpressing mouse C51 or TS/A syngeneic cells and tumor growth pattern and immune cells distribution in tumor mass were investigated. Compared to control cells, mouse Rnaset2-expressing C51 cells showed strong delayed tumor growth. CD86+ M1 macrophages were massively recruited in Rnaset2-expressing C51-derived tumors, with concomitant inhibition of MDSCs and CD206+ M2 macrophages recruitment. At later times, a relevant expansion of intra-tumor CD8+ T cells was also observed. After re-challenge with C51 parental cells, most mice previously injected with Rnaset2-expressing C51 cells still rejected C51 tumor cells, suggesting a Rnaset2-mediated T cell adaptive immune memory response. These results point at T2 RNases as evolutionary conserved oncosuppressors endowed with the ability to inhibit cancer growth in vivo through rebalance of intra-tumor M1/M2 macrophage ratio and concomitant recruitment of adaptive anti-tumor CD8+ T cells.

Targeting and Specific Activation of Antigen-Presenting Cells by Endogenous Antigen-Loaded Nanoparticles Elicits Tumor-Specific Immunity

Immunotherapy has shown tremendous promise for improving cancer treatment. Unfortunately, antigen-presenting cells (APCs) in cancer patients cannot effectively recognize and process tumor antigens to activate host immune responses. In this study, an approach is developed to improve cancer immunotherapy that utilizes endogenous antigen-carrying nanoparticles (EAC-NPs), which encompasses a set of antigens isolated from solid tumors and adjuvants. The EAC-NPs specifically target APCs and subsequently result in enhanced T cell responses and improved antitumor efficacy. Mechanistic studies reveal that the EAC-NPs enhance and prolong the presence of immune compounds in APCs, which ensure persistent antigen loading and stimulation, induce a rapid proliferation of CD4+ and CD8+ T cells, and significantly increase the ratios of intratumoral CD4+ T/Treg and CD8+ T/Treg. The work using nanotechnology provides a promising strategy in improving antitumor immunity by enhancing the immunogenicity and presentation of tumor self-antigens for cancer immunotherapy.

Cross-talk between T Cells and Hematopoietic Stem Cells during Adoptive Cellular Therapy for Malignant Glioma

Purpose: Adoptive T-cell immunotherapy (ACT) has emerged as a viable therapeutic for peripheral and central nervous system (CNS) tumors. In peripheral cancers, optimal efficacy of ACT is reliant on dendritic cells (DCs) in the tumor microenvironment. However, the CNS is largely devoid of resident migratory DCs to function as antigen-presenting cells during immunotherapy. Herein, we demonstrate that cellular interactions between adoptively transferred tumor-reactive T cells and bone marrow-derived hematopoietic stem and progenitor cells (HSPCs) lead to the generation of potent intratumoral DCs within the CNS compartment.Experimental Design: We evaluated HSPC differentiation during ACT in vivo in glioma-bearing hosts and HSPC proliferation and differentiation in vitro using a T-cell coculture system. We utilized FACS, ELISAs, and gene expression profiling to study the phenotype and function of HSPC-derived cells ex vivo and in vivo To demonstrate the impact of HSPC differentiation and function on antitumor efficacy, we performed survival experiments.Results: Transfer of HSPCs with concomitant ACT led to the production of activated CD86+CD11c+MHCII+ cells consistent with DC phenotype and function within the brain tumor microenvironment. These intratumoral DCs largely supplanted abundant host myeloid-derived suppressor cells. We determined that during ACT, HSPC-derived cells in gliomas rely on T-cell-released IFNγ to differentiate into DCs, activate T cells, and reject intracranial tumors.Conclusions: Our data support the use of HSPCs as a novel cellular therapy. Although DC vaccines induce robust immune responses in the periphery, our data demonstrate that HSPC transfer uniquely generates intratumoral DCs that potentiate T-cell responses and promote glioma rejection in situClin Cancer Res; 24(16); 3955-66. ©2018 AACR.

A phase I clinical study of autologous dendritic cell therapy in patients with relapsed or refractory multiple myeloma

Cellular immunotherapy is emerging as a potential immunotherapeutic modality in multiple myeloma (MM). We have developed potent immunotherapeutic agent (VAX-DC/MM) generated by dendritic cells (DCs) loaded with autologous myeloma cells irradiated with ultraviolet B. In this study, we evaluated the safety and efficacy of VAX-DC/MM in patients with relapsed or refractory MM. This trial enrolled relapsed or refractory MM patients who had received both thalidomide- and bortezomib-based therapies. Patients received the intradermal VAX-DC/MM injection every week for 4 weeks. Patients were treated with 5 × 10⁶ or 10 × 10⁶ cells, with nine patients treated at a higher dose. The median time from diagnosis to VAX-DC/MM therapy was 56.6 months (range, 28.5–130.5). Patients had received a median of five prior treatments, and 75% had received autologous stem cell transplantation. VAX-DC therapy was well-tolerated, and the most frequent adverse events were local reactions at the injection site and infusion-related reactions. In seven of nine patients who received 10×10⁶ cells, an immunological response (77.8%) was observed by interferon-gamma ELISPOT assay or a mixed lymphocyte reaction assay for T-cell proliferation. The clinical benefit rate was 66.7% including one (11.1%) with minor response and five (55.6%) with stable disease; three (33.3%) patients showed disease progression. In conclusion, VAX-DC/MM therapy was well-tolerated, and had disease-stabilizing activity in heavily pretreated MM cases. Further studies are needed to increase the efficacy of VAX-DC/MM in patients with MM.

Promoting the accumulation of tumor-specific T cells in tumor tissues by dendritic cell vaccines and chemokine-modulating agents

This protocol describes how to induce large numbers of tumor-specific cytotoxic T cells (CTLs) in the spleens and lymph nodes of mice receiving dendritic cell (DC) vaccines and how to modulate tumor microenvironments (TMEs) to ensure effective homing of the vaccination-induced CTLs to tumor tissues. We also describe how to evaluate the numbers of tumor-specific CTLs within tumors. The protocol contains detailed information describing how to generate a specialized DC vaccine with augmented ability to induce tumor-specific CTLs. We also describe methods to modulate the production of chemokines in the TME and show how to quantify tumor-specific CTLs in the lymphoid organs and tumor tissues of mice receiving different treatments. The combined experimental procedure, including tumor implantation, DC vaccine generation, chemokine-modulating (CKM) approaches, and the analyses of tumor-specific systemic and intratumoral immunity is performed over 30-40 d. The presented ELISpot-based ex vivo CTL assay takes 6 h to set up and 5 h to develop. In contrast to other methods of evaluating tumor-specific immunity in tumor tissues, our approach allows detection of intratumoral T-cell responses to nonmanipulated weakly immunogenic cancers. This detection method can be performed using basic laboratory skills, and facilitates the development and preclinical evaluation of new immunotherapies.

Modulation of chemokines in the tumor microenvironment enhances oncolytic virotherapy for colorectal cancer

An oncolytic poxvirus such as vvDD-CXCL11 can generate potent systemic antitumor immunity as well as targeted oncolysis, yet the antitumor effect is limited probably due to limited homing to and suppressed activity of tumor-specific adaptive immune cells in the tumor microenvironment (TME). We reasoned that a chemokine modulating (CKM) drug cocktail, consisting of IFN-α, poly I:C, and a COX-2 inhibitor, may skew the chemokine (CK) and cytokine profile into a favorable one in the TME, and this pharmaceutical modulation would enhance both the trafficking into and function of antitumor immune cells in the TME, thus increasing therapeutic efficacy of the oncolytic virus. In this study we show for the first time in vivo that the CKM modulates the CK microenvironment but it does not modulate antitumor immunity by itself in a MC38 colon cancer model. Sequential treatment with the virus and then CKM results in the upregulation of Th1-attracting CKs and reduction of Treg-attracting CKs (CCL22 and CXCL12), concurrent with enhanced trafficking of tumor-specific CD8⁺ T cells and NK cells into the TME, thus resulting in the most significant antitumor activity and long term survival of tumor-bearing mice. This novel combined regimen, with the oncolytic virus (vvDD-CXCL11) inducing direct oncolysis and eliciting potent antitumor immunity, and the CKM inducing a favorable chemokine profile in the TME that promotes the trafficking and function of antitumor Tc1/Th1 and NK cells, may have great utility for oncolytic immunotherapy for cancer.

DNA is an efficient booster of dendritic cell-based vaccine

DC-based therapeutic vaccines as a promising strategy against chronic infections and cancer have been validated in several clinical trials. However, DC-based vaccines are complex and require many in vitro manipulations, which makes this a personalized and expensive therapeutic approach. In contrast, DNA-based vaccines have many practical advantages including simplicity, low cost of manufacturing and potent immunogenicity already proven in non-human primates and humans. In this study, we explored whether DC-based vaccines can be simplified by the addition of plasmid DNA as prime or boost to achieve robust CD8-mediated immune responses. We compared the cellular immunity induced in BALB/c and C57BL/6 mice by DC vaccines, loaded either with peptides or optimized SIV Env DNA, and plasmid DNA-based vaccines delivered by electroporation (EP). We found that mature DC loaded with peptides (P-mDC) induced the highest CD8(+) T cell responses in both strains of mice, but those responses were significantly higher in the C57BL/6 model. A heterologous prime-boost strategy (P-DC prime-DNA boost) induced CD8(+) T cell responses similar to those obtained by the P-DC vaccine. Importantly, this strategy elicited robust polyfunctional T cells as well as highest antigen-specific central memory CD8+ T cells in C57BL/6 mice, suggesting long-term memory responses. These results indicate that a DC-based vaccine in combination with DNA in a heterologous DC prime-DNA boost strategy has potential as a repeatedly administered vaccine.

Ubiquitin-modified hepatitis B virus core antigen effectively facilitates antigen presentation and enhances cytotoxic T lymphocyte activity via the cytoplasmic transduction peptide in vitro

Cluster of differentiation (CD)8+ cytotoxic T lymphocytes (CTLs) have a key role in the elimination of hepatitis B virus (HBV)-infected cells. Ubiquitin (Ub) functions as a marker for protein degradation, which may promote the generation of peptides appropriate for major histocompatibility complex class I presentation, while the HBV core antigen (HBcAg) possesses marked immunogenic properties. However, it remains to be elucidated whether Ub-modified HBcAg is able to effectively elicit significant CD8+ CTL activity. In order to address this issue, a prokaryotic vector was constructed to express the Ub-HBcAg-cytoplasmic transduction peptide (CTP). The fusion protein was successfully expressed and subsequently pulsed into bone-marrow-derived dendritic cells (DCs). It was confirmed that with assistance from the cell‑penetrating properties of CTP, the fusion protein was able to directly penetrate into the cytoplasm of DCs. The results revealed that the Ub-HBcAg-CTP fusion protein not only increased the expression of surface molecules in DCs and cytokine secretion from proliferating T cells, but also induced T cells to differentiate into specific CTLs and enhanced their antiviral ability. In conclusion, the Ub-HBcAg-CTP fusion protein promoted DC maturation, enhanced the presentation of targeting antigens and efficiently induced HBcAg‑specific CTL immune responses in vitro.

Low molecular weight hyaluronan-pulsed human dendritic cells showed increased migration capacity and induced resistance to tumor chemoattraction

We have shown that ex vivo pre-conditioning of bone marrow-derived dendritic cells (DC) with low molecular weight hyaluronan (LMW HA) induces antitumor immunity against colorectal carcinoma (CRC) in mice. In the present study we investigated the effects of LMW HA priming on human-tumor-pulsed monocytes-derived dendritic cells (DC/TL) obtained from healthy donors and patients with CRC. LMW HA treatment resulted in an improved maturation state of DC/TL and an enhanced mixed leucocyte reaction activity in vivo. Importantly, pre-conditioning of DC/TL with LMW HA increased their ability to migrate and reduced their attraction to human tumor derived supernatants. These effects were associated with increased CCR7 expression levels in DC. Indeed, a significant increase in migratory response toward CCL21 was observed in LMW HA primed tumor-pulsed monocyte-derived dendritic cells (DC/TL/LMW HA) when compared to LWM HA untreated cells (DC/TL). Moreover, LMW HA priming modulated other mechanisms implicated in DC migration toward lymph nodes such as the metalloproteinase activity. Furthermore, it also resulted in a significant reduction in DC migratory capacity toward tumor supernatant and IL8 in vitro. Consistently, LMW HA dramatically enhanced in vivo DC recruitment to tumor-regional lymph nodes and reduced DC migration toward tumor tissue. This study shows that LMW HA--a poorly immunogenic molecule--represents a promising candidate to improve human DC maturation protocols in the context of DC-based vaccines development, due to its ability to enhance their immunogenic properties as well as their migratory capacity toward lymph nodes instead of tumors.

Vitamin C treatment of mouse bone marrow-derived dendritic cells enhanced CD8(+) memory T cell production capacity of these cells in vivo

Vitamin C has been found to stimulate dendritic cells (DCs) to secrete more IL-12 and thereby drive naïve CD4(+) T cells to differentiate into Th1 cells. In the present study, we evaluated the effect of these vitamin C-treated DCs on CD8(+) T cell differentiation both in vitro and in vivo. Mouse bone marrow-derived DCs were prepared in the presence of GM-CSF and IL-15. With vitamin C treatment, these DCs, when LPS-stimulated, secreted more IL-12p70 and IL-15 than did untreated DCs. And when co-cultured with T cells, they yielded a higher frequency of IFN-γ(+) CD8(+) T cells. Moreover, we found that administering vitamin C-treated and tumor lysate-loaded DCs into mice yielded a higher frequency of CD44(high) CD62L(low) CD8(+) effector and effector memory T cells, which showed an increased ex vivo killing effect of the tumor cells. These DCs also elicited enhanced protective effects against inoculated tumor cells, most probably by way of the increased cytotoxic T cells, as was revealed by the decreased growth of the inoculated tumor cells in these mice. This ex vivo vitamin C treatment effect on DCs can be considered as a strategy for boosting DC vaccination potency against tumors.

A novel polysaccharide from the seeds of Plantago asiatica L. induces dendritic cells maturation through toll-like receptor 4

In this study, we investigated the effect of a polysaccharide purified from the seeds of Plantago asiatica L. (PLP-2) on the phenotypic and functional maturation of murine bone marrow-derived dendritic cells (DCs) and relevant mechanisms. The results showed that PLP-2 increased the expression of maturation markers major histocompatibility complex II, CD86, CD80, and CD40 on DCs. Consistent with the changes in the phenotypic markers, functional assay for DCs maturation showed that PLP-2 decreased DCs endocytosis and increased intracellular interleukin (IL)-12 levels and allostimulatory activity. Furthermore, using a syngeneic T cell activation model, we found that PLP-2 treated DCs presented ovalbumin antigen to T cells more efficiently as demonstrated by increased T cell proliferation. In addition, the effects of PLP-2 on DCs were significantly impaired by treating the cells with anti-TLR4 antibody prior to PLP-2 treatment, implying direct interaction between PLP-2 and TLR4 on cell surface. These results suggested that PLP-2 may induce DCs maturation through TLR4. Our results may have important implications for our understanding on the molecular mechanisms of immunopotentiating action of the polysaccharides from plants.

Recombinant human lactoferrin induces human and mouse dendritic cell maturation via Toll-like receptors 2 and 4

Lactoferrin, a key component of innate immunity, is a cationic monomeric 80-kDa glycoprotein of the transferrin superfamily. Recombinant human lactoferrin, known as talactoferrin (TLF), induces a distinct functional maturation program in human dendritic cells (DCs) derived from peripheral blood monocytes. However, the receptors and molecular mechanisms involved in this induction have not been fully determined. By exploiting genome-wide transcription profiling of immature DCs, TNF-α- and IL-1β-matured DCs (m-DCs), and TLF-matured DCs (TLF-DCs), we have detected a set of transcripts specific for m-DCs and one specific for TLF-DCs. Functional network reconstruction highlighted, as expected, the association of m-DC maturation with IL-1β, TNF-α, and NF-κB, whereas TLF-DC maturation was associated with ERK and NF-κB. This involvement of ERK and NF-κB transduction factors suggests direct involvement of Toll-like receptors (TLRs) in TLF-induced maturation. We have used MyD88 inhibition and siRNA silencing TLRs on human DCs and mouse TLR-2-knockout cells, to show that TLF triggers the maturation of both human and mouse DCs through TLR-2 and TLR-4.

Dendritic cells in cancer immunotherapy: vaccines and combination immunotherapies

Dendritic cells (DCs) are specialized immunostimulatory cells involved in the induction and regulation of immune responses. The feasibility of large-scale ex vivo generation of DCs from patients' monocytes allows for therapeutic application of ex vivo-cultured DCs to bypass the dysfunction of endogenous DCs, restore immune surveillance, induce cancer regression or stabilization or delay or prevent its recurrence. While the most common paradigm of the therapeutic application of DCs reflects their use as cancer 'vaccines', additional and potentially more effective possibilities include the use of patients' autologous DCs as parts of more comprehensive therapies involving in vivo or ex vivo induction of tumor-reactive T cells and the measures to counteract systemic and local immunosuppression in tumor-bearing hosts. Ex vivo-cultured DCs can be instructed to acquire distinct functions relevant for the induction of effective cancer immunity (DC polarization), such as the induction of different effector functions or different homing properties of tumor-specific T cells (delivery of 'signal 3' and 'signal 4'). These considerations highlight the importance of the application of optimized conditions for the ex vivo culture of DCs and the potential combination of DC therapies with additional immune interventions to facilitate the entry of DC-induced T cells to tumor tissues and their local antitumor functions.

Multifunctional nanoparticles co-delivering Trp2 peptide and CpG adjuvant induce potent cytotoxic T-lymphocyte response against melanoma and its lung metastasis

Immunotherapy has shown the potential to become an essential component of the successful treatment of various malignancies. In many cases, such as in melanoma, however, induction of a potent and specific T-cell response against the endogenous antigen or self-antigen still remains a major challenge. To induce a potent MHC I-restricted cytotoxic T-lymphocyte (CTL) response, cytosol delivery of an exogenous antigen into dendritic cells is preferred, if not required. Lipid-calcium-phosphate (LCP) nanoparticles represent a new class of intracellular delivery systems for impermeable drugs. We are interested in exploring the potential of LCP NPs for use as a peptide vaccine delivery system for cancer therapy. To increase the encapsulation of Trp2 peptide into the calcium phosphate precipitate core of LCP, two phosphor-serine residues were added to the N-terminal of the peptide (p-Trp2). CpG ODN was also co-encapsulated with p-Trp2 as an adjuvant. The NPs were further modified with mannose to enhance and prolong the cargo deposit into the lymph nodes (LNs), which ensured persistent antigen loading and stimulation. Compared with free Trp2 peptide/CpG, vaccination with LCP encapsulating p-Trp2 and CpG resulted in superior inhibition of tumor growth in both B16F10 subcutaneous and lung metastasis models. An IFN-γ production assay and in vivo CTL response study revealed that the improved efficacy was a result of a Trp2-specific immune response. Thus, encapsulation of phospho-peptide antigens into LCP may be a promising strategy for enhancing the immunogenicity of poorly immunogenic self-antigens for cancer therapy.

Phenotypic plasticity of MDSC in cancers

Myeloid-derived suppressor cells (MDSCs) were initially reported as suppressor of the adaptive immune responses against cancer and other diseases. However, emerging evidence suggest that MDSCs may also support anti-tumor immune responses under certain conditions or may inhibit tumor growth. In the present mini-review, we suggest that such opposing functions of MDSCs are due to phenotypic plasticity of the myeloid cells, allowing them to produce a diverse form of morphology, physiological state, and function in response to environmental conditions. Therefore, they can be manipulated by means of immune modulators to overcome their immune suppressive function.

Oral administration of soluble β-glucans extracted from Grifola frondosa induces systemic antitumor immune response and decreases immunosuppression in tumor-bearing mice

Maitake D (MD)-Fraction is a highly purified soluble β-glucan derived from Grifola frondosa (an oriental edible mushroom). Intraperitoneal (i.p.) injection of MD-Fraction has been reported to inhibit tumor growth via enhancement of the host immune system. In this study, we demonstrated that oral administration of MD-Fraction as well as i.p. injection significantly inhibited tumor growth in murine tumor models. After oral administration, MD-Fraction was not transferred to the blood in its free form but was captured by antigen-presenting cells such as macrophages and dendritic cells (DCs) present in the Peyer's patch. The captured MD-Fraction was then transported to the spleen, thereby inducing the systemic immune response. Our study showed that MD-Fraction directly induced DC maturation via a C-type lectin receptor dectin-1 pathway. The therapeutic response of orally administered MD-Fraction was associated with (i) induced systemic tumor-antigen specific T cell response via dectin-1-dependent activation of DCs, (ii) increased infiltration of the activated T cells into the tumor and (iii) decreased number of tumor-caused immunosuppressive cells such as regulatory T cells and myeloid-derived suppressor cells. Our preclinical study suggests that MD-Fraction is a useful oral therapeutic agent in the management of patients with cancer.

Immunobiology of human mucin 1 in a preclinical ovarian tumor model

Epithelial ovarian cancer is an aggressive malignancy, with a low 5-year median survival. Continued improvement on the development of more effective therapies depends in part on the availability of adequate preclinical models for in vivo testing of treatment efficacy. Mucin 1 (MUC1) glycoprotein is a tumor-associated antigen overexpressed in ovarian cancer cells, making it a potential target for immune therapy. To create a preclinical mouse model for MUC1-positive ovarian tumors, we generated triple transgenic (Tg) mice that heterozygously express human MUC1(+/-) as a transgene, and carry the conditional K-rasG12D oncoallele (loxP-Stop-loxP-K-ras(G12D/+)) and the floxed Pten gene (Pten/(loxP/loxP)). Injection of Cre recombinase-encoding adenovirus (AdCre) in the ovarian bursa of triple (MUC1KrasPten) Tg mice triggers ovarian tumors that, in analogy to human ovarian cancer, express strongly elevated MUC1 levels. The tumors metastasize loco-regionally and are accompanied by high serum MUC1, closely mimicking the human disease. Compared with the KrasPten mice with tumors, the MUC1KrasPten mice show increased loco-regional metastasis and augmented accumulation of CD4+Foxp3+ immune-suppressive regulatory T cells. Vaccination of MUC1KrasPten mice with type 1 polarized dendritic cells (DC1) loaded with a MUC1 peptide (DC1-MUC1) can circumvent tumor-mediated immune suppression in the host, activate multiple immune effector genes and effectively prolong survival. Our studies report the first human MUC1-expressing, orthotopic ovarian tumor model, reveal novel MUC1 functions in ovarian cancer biology and demonstrate its suitability as a target for immune-based therapies.

Optimizing dendritic cell-based immunotherapy: tackling the complexity of different arms of the immune system

Earlier investigations have revealed a surprising complexity and variety in the range of interaction between cells of the innate and adaptive immune system. Our understanding of the specialized roles of dendritic cell (DC) subsets in innate and adaptive immune responses has been significantly advanced over the years. Because of their immunoregulatory capacities and because very small numbers of activated DC are highly efficient at generating immune responses against antigens, DCs have been vigorously used in clinical trials in order to elicit or amplify immune responses against cancer and chronic infectious diseases. A better insight in DC immunobiology and function has stimulated many new ideas regarding the potential ways forward to improve DC therapy in a more fundamental way. Here, we discuss the continuous search for optimal in vitro conditions in order to generate clinical-grade DC with a potent immunogenic potential. For this, we explore the molecular and cellular mechanisms underlying adequate immune responses and focus on most favourable DC culture regimens and activation stimuli in humans. We envisage that by combining each of the features outlined in the current paper into a unified strategy, DC-based vaccines may advance to a higher level of effectiveness.

Cellular immunotherapy using dendritic cells against multiple myeloma

Cellular therapy with dendritic cells (DCs) is emerging as a useful immunotherapeutic tool to treat multiple myeloma (MM). DC-based idiotype vaccination was recently suggested to induce idiotype-specific immune responses in MM patients. However, the clinical results so far have been largely disappointing, and the clinical effectiveness of such vaccinations in MM still needs to be demonstrated. DC-based therapies against MM may need to be boosted with other sources of tumor-associated antigens, and potent DCs should be recruited to increase the effectiveness of treatment. DCs with both high migratory capacity and high cytokine production are very important for effective DC-based cancer vaccination in order to induce high numbers of Th1-type CD4⁺ T cells and CD8⁺ cytotoxic T lymphocytes. The tumor microenvironment is also important in the regulation of tumor cell growth, proliferation, and the development of therapeutic resistance after treatment. In this review, we discuss how the efficacy of DC vaccination in MM can be improved. In addition, novel treatment strategies that target not only myeloma cells but also the tumor microenvironment are urgently needed to improve treatment outcomes.

Enhancement of CTLs induced by DCs loaded with ubiquitinated hepatitis B virus core antigen

AIM: To investigate whether hepatitis B virus (HBV) could induce a hepatitis B virus core antigen (HBcAg)-specific cytotoxic T lymphocyte (CTL) response in vitro by dendritic cells (DCs) transduced with lentiviral vector-encoding ubiquitinated hepatitis B virus core antigen (LV-Ub-HBcAg).

METHODS: Recombinant LV-Ub-HBcAg were transfected into highly susceptible 293 T cells to obtain high virus titres. Bone marrow-derived DCs isolated from BALB/c mice were cultured with recombinant granulocyte-macrophage colony-stimulating factor and recombinant interleukin (IL)-4. LV-Ub-HBcAg, lentiviral vector-encoding hepatitis B virus core antigen (LV-HBcAg), lentiviral vector (LV) or lipopolysaccharide were added to induce DC maturation, and the DC phenotypes were analyzed by flow cytometry. The level of IL-12 in the supernatant was detected by enzyme-linked immunosorbent assay (ELISA). T lymphocytes were proliferated using Cell Counting Kit-8. DCs were cultured and induced to mature using different LVs, and co-cultured with allogeneic T cells to detect the secretion levels of IL-2, IL-4, IL-10 and interferon-γ in the supernatants of T cells by ELISA. Intracellular cytokines of proliferative T cells were analyzed by flow cytometry, and specific CTL activity was measured by a lactate dehydrogenase release assay.

RESULTS: LV-Ub-HBcAg-induced DCs secreted more IL-12 and upregulated the expression of CD80, CD86 and major histocompatibility class II. DCs sensitised by different LVs effectively promoted cytokine secretion; the levels of IL-2 and interferon-γ induced by LV-Ub-HBcAg were higher than those induced by LV-HBcAg. Compared with LV-HBcAg-transduced DCs, LV-Ub-HBcAg-transduced DCs more efficiently stimulated the proliferation of T lymphocytes and generated HBcAg-specific cytotoxic T lymphocytes.

CONCLUSION: LV-Ub-HBcAg effectively induced DC maturation. The mature DCs efficiently induced T cell polarisation to Th1 and generated HBcAg-specific CTLs.

NOD/scid IL-2Rg(null) mice: a preclinical model system to evaluate human dendritic cell-based vaccine strategies in vivo

BACKGROUND

To date very few systems have been described for preclinical investigations of human cellular therapeutics in vivo. However, the ability to carry out comparisons of new cellular vaccines in vivo would be of substantial interest for design of clinical studies. Here we describe a humanized mouse model to assess the efficacy of various human dendritic cell (DC) preparations. Two reconstitution regimes of NOD/scid IL2Rg(null) (NSG) mice with adult human peripheral blood mononuclear cells (PBMC) were evaluated for engraftment using 4-week and 9-week schedules. This led to selection of a simple and rapid protocol for engraftment and vaccine evaluation that encompassed 4 weeks.

METHODS

NSG recipients of human PBMC were engrafted over 14 days and then vaccinated twice with autologous DC via intravenous injection. Three DC vaccine formulations were compared that varied generation time in vitro (3 days versus 7 days) and signals for maturation (with or without Toll-like receptor (TLR)3 and TLR7/8 agonists) using MART-1 as a surrogate antigen, by electroporating mature DC with in vitro transcribed RNA encoding full length protein. After two weekly vaccinations, the splenocyte populations containing human lymphocytes were recovered 7 days later and assessed for MART-1-specific immune responses using MHC-multimer-binding assays and functional assessment of specific killing of melanoma tumor cell lines.

RESULTS

Human monocyte-derived DC generated in vitro in 3 days induced better MART-1-specific immune responses in the autologous donor T cells present in the humanized NSG mice. Moreover, consistent with our in vitro observations, vaccination using mature DC activated with TLR3 and TLR7/8 agonists resulted in enhanced immune responses in vivo. These findings led to a ranking of the DC vaccine effects in vivo that reflected the hierarchy previously found for these mature DC variations in vitro.

CONCLUSIONS

This humanized mouse model system enables comparisons among different DC vaccine types to be rapidly assessed in vivo. In addition, ex vivo analyses of human CD3+ T cells recovered from the spleens of these mice are also possible, including studies on lymphocyte subsets, Th1/Th2 polarization, presence of regulatory T cells and the impact of DC vaccination on their functions.

Enhancement of protective immunity against intracellular bacteria using type-1 polarized dendritic cell (DC) vaccine

The development of effective vaccine strategies for intracellular bacteria, including tuberculosis, is one of the major frontiers of medical research. Our previous studies showed that dendritic cell (DC) vaccine is a promising approach for eliciting protective immunity against intracellular bacteria. However, it has been reported that standard fully mature DCs show reduced ability to produce IL-12p70 upon subsequent interaction with antigen (Ag)-specific T cells, limiting their in vivo performance for vaccines. Recently, we found that such "DC exhaustion" could be prevented by the presence of IL-4 and IFN-γ during the maturation of mouse DCs (type-1 polarization), resulting in improved induction of anti-tumor immunity in cancer. Here we show that such type-1 polarized DCs promote dramatic enhancement of protective immunity against an intracellular bacterium, Listeria monocytogenes. Murine bone marrow-derived DCs were cultured and matured with LPS, IL-4 and IFN-γ (type-1 polarized DCs), and with LPS alone (non-polarized DCs). DCs were loaded with listeriolysin O (LLO) 91-99, H2-K(d)-restricted epitope of L. monocytogenes, and were injected into naïve BALB/c mice intravenously. Type-1 polarized DCs produced significantly higher levels of IL-12p70 than non-polarized DCs in vitro, and this vaccine strongly enhanced LLO 91-99-specific CD8(+) T cells exhibiting epitope-specific cytotoxic activity and IFN-γ production, leading to significant induction of protective immunity against L. monocytogenes. Type-1 polarized DCs are potential candidates for enhancing protective immunity in the design of effective vaccination strategies against intracellular bacteria.

Poly(I:C)-induced tumour cell death leads to DC maturation and Th1 activation

Dendritic cells (DCs) have the ability to generate peptide epitopes for MHC class I molecules derived from apoptotic tumour cells for direct recognition by cytotoxic T cells. This function has lead to DCs being used in vaccine strategies. In this study, we investigate the effect of inducing apoptosis in tumour cell lines using IFN-γ and poly(I:C), the subsequent maturation of the endocytosing DC and its ability to direct the resulting T cell response. We show that uptake of poly(I:C)-induced apoptotic tumour cells leads to DC maturation and activation with a Th1 cell polarising capacity. In contrast, these effects are not seen by DCs loaded with γ-irradiated apoptotic tumour cells. We propose that the manner in which tumour cells are induced to die can have a profound effect on the endocytosing DC and the resulting T cell response.

Cytotoxic T lymphocytes simultaneously targeting multiple tumor-associated antigens to treat EBV negative lymphoma

Although immunotherapy with Epstein-Barr virus (EBV)-specific cytotoxic T lymphocytes (CTLs) can treat EBV-associated Hodgkin and non-Hodgkin lymphoma (HL/NHL), more than 50% of such tumors are EBV negative. We now describe an approach that allows us to consistently generate, in a single line, CTLs that recognize a wide spectrum of nonviral tumor-associated antigens (TAAs) expressed by human HL/NHL, including Survivin, MAGE-A4, Synovial sarcoma X (SSX2), preferentially expressed antigen in melanoma (PRAME) and NY-ESO-1. We could generate these CTLs from nine of nine healthy donors and five of eight lymphoma patients, irrespective of human leukocyte antigen (HLA) type. We reactivated TAA-directed T cells ex vivo, by stimulation with dendritic cells (DCs) pulsed with overlapping peptide libraries spanning the chosen antigens in the presence of an optimized Th1-polarizing, prosurvival/proliferative and Treg inhibitory cytokine combination. The resultant lines of CD4(+) and CD8(+), polycytokine-producing T cells are directed against a multiplicity of epitopes expressed on the selected TAAs, with cytolytic activity against autologous tumor cells. Infusion of such multispecific monocultures may extend the benefits of CTL therapy to treatment even of EBV negative HL and NHL.

Therapeutic vaccines in renal cell carcinoma

Metastatic renal cell carcinoma (mRCC) is a lethal disease. The advent of tyrosine kinase inhibitors (TKIs) has changed the disease process, yet the majority of patients will develop treatment-resistant disease. IL-2 based immunotherapy in mRCC is the only US FDA-approved treatment with curative results. Immunotherapeutic vaccine approaches to mRCC have been under investigation for several decades with mixed results. The recent FDA-approval of the first cellular immunotherapy in prostate cancer (Provenge(®)) has reinvigorated the search for similar vaccines approaches in mRCC. This review introduces the concepts and different features required for a successful anticancer vaccine approach.

Tumor immunotherapy using adenovirus vaccines in combination with intratumoral doses of CpG ODN

The combination of viral vaccination with intratumoral (IT) administration of CpG ODNs is yet to be investigated as an immunotherapeutic treatment for solid tumors. Here, we show that such a treatment regime can benefit survival of tumor-challenged mice. C57BL/6 mice bearing ovalbumin (OVA)-expressing EG.7 thymoma tumors were therapeutically vaccinated with adenovirus type 5 encoding OVA (Ad5-OVA), and the tumors subsequently injected with the immunostimulatory TLR9 agonist, CpG-B ODN 1826 (CpG), 4, 7, 10, and 13 days later. This therapeutic combination resulted in enhanced mean survival times that were more than 3.5× longer than naïve mice, and greater than 40% of mice were cured and capable of resisting subsequent tumor challenge. This suggests that an adaptive immune response was generated. Both Ad5-OVA and Ad5-OVA + CpG IT treatments led to significantly increased levels of H-2 K(b)-OVA-specific CD8+ lymphocytes in the peripheral blood and intratumorally. Lymphocyte depletion studies performed in vivo implicated both NK cells and CD8+ lymphocytes as co-contributors to the therapeutic effect. Analysis of tumor infiltrating lymphocytes (TILs) on day 12 post-tumor challenge revealed that mice treated with Ad5-OVA + CpG IT possessed a significantly reduced percentage of regulatory T lymphocytes (Tregs) within the CD4+ lymphocyte population, compared with TILs isolated from mice treated with Ad5-OVA only. In addition, the proportion of CD8+ TILs that were OVA-specific was reproducibly higher in the mice treated with Ad5-OVA + CpG IT compared with other treatment groups. These findings highlight the therapeutic potential of combining intratumoral CpG and vaccination with virus encoding tumor antigen.

Successful cross-presentation of allogeneic myeloma cells by autologous alpha-type 1-polarized dendritic cells as an effective tumor antigen in myeloma patients with matched monoclonal immunoglobulins

For wide application of a dendritic cell (DC) vaccination in myeloma patients, easily available tumor antigens should be developed. We investigated the feasibility of cellular immunotherapy using autologous alpha-type 1-polarized dendritic cells (αDC1s) loaded with apoptotic allogeneic myeloma cells, which could generate myeloma-specific cytotoxic T lymphocytes (CTLs) against autologous myeloma cells in myeloma patients. Monocyte-derived DCs were matured by adding the αDC1-polarizing cocktail (TNFα/IL-1β/IFN-α/IFN-γ/poly-I:C) and loaded with apoptotic allogeneic CD138(+) myeloma cells from other patients with matched monoclonal immunoglobulins as a tumor antigen. There were no differences in the phenotypic expression between αDC1s loaded with apoptotic autologous and allogeneic myeloma cells. Autologous αDC1s effectively took up apoptotic allogeneic myeloma cells from other patients with matched subtype. Myeloma-specific CTLs against autologous target cells were successfully induced by αDC1s loaded with allogeneic tumor antigen. The cross-presentation of apoptotic allogeneic myeloma cells to αDC1s could generate CTL responses between myeloma patients with individual matched monoclonal immunoglobulins. There was no difference in CTL responses between αDC1s loaded with autologous tumor antigen and allogeneic tumor antigen against targeting patient's myeloma cells. Our data indicate that autologous DCs loaded with allogeneic myeloma cells with matched immunoglobulin can generate potent myeloma-specific CTL responses against autologous myeloma cells and can be a highly feasible and effective method for cellular immunotherapy in myeloma patients.

Type I and II interferons enhance dendritic cell maturation and migration capacity by regulating CD38 and CD74 that have synergistic effects with TLR agonists

The major limitation for the maturation of dendritic cells (DCs) using Toll-like receptor (TLR) agonists is their decreased ability to migrate into lymph nodes compared with conventional DCs. CD38 can be used as a multifunctional marker to modulate migration, survival and Th1 responses of DCs. CD74 has been shown to negatively regulate DC migration. The goal of this study was to investigate the combinations of TLR agonists and interferons (IFNs) that most effectively regulate CD38 and CD74 expression on DCs. Synergistic TLR agonist stimulation in combination with IFN-α and IFN-γ was the best method for regulating CD38 and CD74 expression and inducing the highest secretion of IL-12p70. An in vitro migration assay showed that DCs treated with this combination had significantly enhanced migratory ability, similar to that observed in cells expressing CD38, CD74 and CCR7. The results of this study suggest that an alternative maturation protocol in which two TLR ligands are combined with type I and II IFNs generates potent DCs that have both a high migratory capacity and high IL-12p70 production.

Recent developments in cancer vaccines

The adoptive transfer of cancer Ag-specific effector T cells in patients can result in tumor rejection, thereby illustrating the immune system potential for cancer therapy. Ideally, one would like to directly induce efficient tumor-specific effector and memory T cells through vaccination. Therapeutic vaccines have two objectives: priming Ag-specific T cells and reprogramming memory T cells (i.e., a transformation from one type of immunity to another, for example, regulatory to cytotoxic). Recent successful phase III clinical trials showing benefit to the patients revived cancer vaccines. Dendritic cells (DCs) are essential in generation of immune responses, and as such represent targets and vectors for vaccination. We have learned that different DC subsets elicit different T cells. Similarly, different activation methods result in DCs able to elicit distinct T cells. We contend that a careful manipulation of activated DCs will allow cancer immunotherapists to produce the next generation of highly efficient cancer vaccines.

Chemokine expression from oncolytic vaccinia virus enhances vaccine therapies of cancer

Tumor vaccines can induce robust immune responses targeting tumor antigens in the clinic, but antitumor effects have been disappointing. One reason for this is ineffective tumor infiltration of the cytotoxic T lymphocytes (CTLs) produced. Oncolytic viruses are capable of selectively replicating within tumor tissue and can induce a strong immune response. We therefore sought to determine whether these therapies could be rationally combined such that modulation of the tumor microenvironment by the viral therapy could help direct beneficial CTLs induced by the vaccine. As such, we examined the effects of expressing chemokines from oncolytic vaccinia virus, including CCL5 (RANTES), whose receptors are expressed on CTLs induced by different vaccines, including type-1-polarized dendritic cells (DC1). vvCCL5, an oncolytic vaccinia virus expressing CCL5, induced chemotaxis of lymphocyte populations in vitro and in vivo, and displayed improved safety in vivo. Interestingly, enhanced therapeutic benefits with vvCCL5 in vivo correlated with increased persistence of the viral agent exclusively within the tumor. When tumor-bearing mice were both vaccinated with DC1 and treated with vvCCL5 a further significant enhancement in tumor response was achieved which correlated with increased levels of tumor infiltrating lymphocytes. This approach therefore represents a novel means of combining biological therapies for cancer treatment.

Monocyte-derived DC maturation strategies and related pathways: a transcriptional view

Ex vivo production of highly stimulator mature dendritic cells (DCs) for cellular therapy has been used to treat different pathological conditions with the aim of inducing a specific immune response. In the last decade, several protocols have been developed to mature monocyte-derived DCs: each one has led to the generation of DCs showing different phenotypes and stimulatory abilities, but it is not yet known which one is the best for inducing effective immune responses. We grouped several different maturation protocols according to the downstream pathways they activated and reviewed the shared features at a transcriptomic level to reveal the potential of DCs matured by each protocol to develop Th-polarized immune responses.

Dendritic cells and immunity against cancer

T cells can reject established tumours when adoptively transferred into patients, thereby demonstrating the power of the immune system for cancer therapy. However, it has proven difficult to maintain adoptively transferred T cells in the long term. Vaccines have the potential to induce tumour-specific effector and memory T cells. However, clinical efficacy of current vaccines is limited, possibly because tumours skew the immune system by means of myeloid-derived suppressor cells, inflammatory type 2 T cells and regulatory T cells (Tregs), all of which prevent the generation of effector cells. To improve the clinical efficacy of cancer vaccines in patients with metastatic disease, we need to design novel and improved strategies that can boost adaptive immunity to cancer, help overcome Tregs and allow the breakdown of the immunosuppressive tumour microenvironment. This can be achieved by exploiting the fast increasing knowledge about the dendritic cell (DC) system, including the existence of distinct DC subsets that respond differentially to distinct activation signals, (functional plasticity), both contributing to the generation of unique adaptive immune responses. We foresee that these novel cancer vaccines will be used as monotherapy in patients with resected disease and in combination with drugs targeting regulatory/suppressor pathways in patients with metastatic disease.

A polysaccharide extracted from Grifola frondosa enhances the anti-tumor activity of bone marrow-derived dendritic cell-based immunotherapy against murine colon cancer

We previously isolated the novel heteropolysaccharide maitake Z-fraction (MZF) from the maitake mushroom (Grifola frondosa), and demonstrated that MZF significantly inhibited tumor growth by inducing cell-mediated immunity. In this study, we demonstrated that MZF upregulated the expression of CD80, CD86, CD83, and MHC II on bone marrow-derived dendritic cells (DCs) and significantly increased interleukin-12 (IL-12) and tumor necrosis factor-alpha production by DCs in a dose-dependent manner. MZF-treated DCs significantly stimulated both allogeneic and antigen-specific syngenic T cell responses and enhanced antigen-specific interferon-gamma (IFN-gamma) production by syngenic CD4(+) T cells; however, MZF-treated DCs did not affect IL-4 production. Furthermore, the enhancement of IFN-gamma production in CD4(+) T cells, which was induced by MZF-treated DCs, was completely inhibited by the addition of an anti-IL-12 antibody. These results indicate that MZF induced DC maturation and antigen-specific Th1 response by enhancing DC-produced IL-12. We also demonstrated that DCs pulsed with colon-26 tumor lysate in the presence of MZF induced both therapeutic and preventive effects on colon-26 tumor development in BALB/c mice. These results suggest that MZF could be a potential effective adjuvant to enhance immunotherapy using DC-based vaccination.

Dendritic cell vaccine in addition to FOLFIRI regimen improve antitumor effects through the inhibition of immunosuppressive cells in murine colorectal cancer model

Although chemotherapy is still one of the best treatments for most cancers, immunotherapies such as dendritic cell (DC) vaccines have emerged as an alternative protocol for destroying residual tumors. In this study, we investigated antitumor effects of the combined therapy using DC vaccine and irinotecan plus infusional 5-fluorouracil and leucovorin (FOLFIRI) which have been clinically used for the treatment of colorectal cancer. A maximum tolerated dose of FOLFIRI was preliminarily determined for MC38/CEA2 colorectal cancer model. Vaccination with DC expressing carcinoembryonic antigen (CEA) enhanced antitumor effect after FOLFIRI treatment. The combined therapy also increased CEA-specific Th1 and cytotoxic T-cell responses. Interestingly, although FOLFIRI treatment rather showed a rebound in the number of myeloid-derived suppressor cells (MDSC) and regulatory T-cells (Treg) after 14 days, additional DC vaccine could inhibit the rebound of these immunosuppressive cells. Furthermore, mice cured by the combined therapy showed antigen-specific T-cell responses and resistance against challenge of MC38/CEA2 compared with mice cured with FOLFIRI. These results demonstrated that DC vaccine in addition to FOLFIRI regimen could improve antitumor effects through the inhibition of immunosuppressive tumor environments in murine colorectal cancer model, and may provide knowledge useful for the design of chemo-immunotherapeutic strategies for the treatment of colorectal carcinoma in clinical trials.