Anti-tumor immune response induced by dendritic cells transduced with truncated PSMA IRES 4-1BBL recombinant adenoviruses

Optimal conditions for adenoviral transduction of immature dendritic cells without affecting the tolerogenic activity of DC-based immunotherapy

Dendritic cells (DCs) play a pivotal role in maintaining immune tolerance. Using recombinant adenovirus (rAd) to deliver vectors to immature dendritic cells (imDCs) is an important method for studying the tolerogenic function of DCs. We found that using RPMI medium and a higher MOI during transduction increased the expression of CD80, CD86, and MHC-II on the surface of imDCs. Our data reveal a significant increase in the secretion of the pro-inflammatory cytokine IL-6 in the group showing the most pronounced phenotypic changes. In the mouse heart transplant model, imDCs with unstable phenotype and function due to adenoviral transduction resulted in an increased proportion of Th1 and Th17 cells in recipients. However, these effects can be managed, and our proposed optimized transduction strategy significantly minimizes these adverse effects. Our study holds significant implications for the development and optimization of immunotherapy utilizing tolerogenic dendritic cells.

4-1BB antibody enhances cytotoxic activity of natural killer cells against prostate cancer cells via NKG2D agonist combined with IL-27

Aims: To enhance the cytotoxicity of natural killer (NK) cells against prostate cancer cells via NKG2D agonist, with 4-1BB antibody and IL-27 combination. Materials & methods: FACS was used to detect degranulation and cell surface receptors in NK cells isolated from healthy donors. Cytokine concentrations were measured using ELISA. NK-cell cytotoxicity was analyzed using Cell Counting Kit-8. Results: NKG2D agonist, 4-1BB antibody and IL-27 combination treatment improved the activating receptor expression and IFN-γ and TNF-α secretion but decreased the suppressive receptor CD158a expression and IL-10 secretion in NK cells. The combined treatment enhanced NK-cell cytotoxicity against both PC3 and DU145 cells with concurrent enhanced STAT3 activation. Conclusion: 4-1BB antibody and IL-27 improved NKG2D agonist function in NK cells against prostate cancer cells.

Immune-based therapies for metastatic prostate cancer: an update

Prostate cancer (PC) is a common malignancy among elderly males and is noncurable once it becomes metastatic. In recent years, a number of antigen-delivery systems have emerged as viable and promising immunotherapeutic agents against PC. The approval of sipuleucel-T by the US FDA for the treatment of males with asymptomatic or minimally symptomatic castrate resistant PC was a landmark in cancer immunotherapy, making this the first approved immunotherapeutic. A number of vaccines are under clinical investigation, each having its own set of advantages and disadvantages. Here, we discuss the basic technologies underlying these different delivery modes, we discuss the completed and current human clinical trials, as well as the use of vaccines in combination with immune checkpoint inhibitors.

E2F-1 promotes DAPK2-induced anti-tumor immunity of gastric cancer cells by targeting miR-34a

Activation of the transcription factor E2F-1 gene is a negative event in dendritic cell (DC) maturation process. Down-regulation of E2F1 causes immaturity of DC thereby stopping antigen production which in turn leads to inhibition of immune responses. E2F-1-free stimulates the NF-kB signaling pathway, leading to activation of monocytes and several other transcription factor genes. In the study, we report that down-regulation of E2F-1 in DCs promote anti-tumor immune response in gastric cancer (GC) cells through a novel mechanism. DCs were isolated from peripheral blood mononuclear cells. E2F-1 small interfering RNA (E2F-1-shRNA) induced down-regulation of E2F-1 mRNA and protein expression in DCs. Furthermore, we identified the E2F-1-shRNA targeted the CD80, CD83, CD86, and MHC II molecules, promoted their expression, and induced T lymphocytes proliferation activity and up-regulation of IFN-Ī³ production and GC cell killing effect, which significantly correlated with the cytotoxic T lymphocytes activated by E2F-1-shRNA DCs. The higher expression of miR-34a was found which was significantly correlated with the DC enhancing anti-tumor immunity against gastric cancer cell, and miR-34a potently targeted DAPK2 and Sp1, both of which were involved in the deactivation of E2F-1. Moreover, in E2F-1-DC-down-regulation in mice, GC transplantation tumors displayed down-regulation of Sp1, DAPK2, Caspase3, and Caspase7 and progressed to anti-tumor immunity. Collectively, our data uncover an E2F-1-mediated mechanism for the control of DC anti-tumor immunity via miR-34a-dependent down-regulation of E2F-1 expression and suggest its contribution to GC immunotherapy.

Potent anti-prostate cancer immune response induced by dendritic cells transduced with recombinant adenoviruses encoding 4-1BBL combined with cytokine-induced killer cells

AIM

To test the effect of dendritic cells (DCs) transduced with recombinant adenoviruses encoding 4-1BBL combined with cytokine-induced killer cells (CIKs) against prostate cancer.

METHOD

Flow cytometry was used to detect the surface markers of the co-cultured cells, and cytotoxicity against prostate cancer cells in vitro as well as antitumor activities in vivo were observed.

RESULTS

Our results showed that Ad-4-1BBL-transduced DCs could increase percentage of CD3(+)CD56(+) cells in CIKs, and CIKs co-cultured with Ad-4-1BBL-transduced DCs could augment the secretion of IL-12 and IFN-γ and decrease TGF-β production. In addition, Ad-4-1BBL-transduced DCs enhanced the cytotoxicity of CIKs against prostate cancer and resulted in inhibition of tumor growth and tumor-bearing animals' survival.

CONCLUSION

These results demonstrate that 4-1BBL-engineered DCs can improve CIKs cytotoxicity against prostate cancer cells.

4-1BBL enhances CD8+ T cell responses induced by vectored vaccines in mice but fails to improve immunogenicity in rhesus macaques

T cells play a central role in the immune response to many of the world's major infectious diseases. In this study we investigated the tumour necrosis factor receptor superfamily costimulatory molecule, 4-1BBL (CD137L, TNFSF9), for its ability to increase T cell immunogenicity induced by a variety of recombinant vectored vaccines. To efficiently test this hypothesis, we assessed a number of promoters and developed a stable bi-cistronic vector expressing both the antigen and adjuvant. Co-expression of 4-1BBL, together with our model antigen TIP, was shown to increase the frequency of murine antigen-specific IFN-γ secreting CD8(+) T cells in three vector platforms examined. Enhancement of the response was not limited by co-expression with the antigen, as an increase in CD8(+) immunogenicity was also observed by co-administration of two vectors each expressing only the antigen or adjuvant. However, when this regimen was tested in non-human primates using a clinical malaria vaccine candidate, no adjuvant effect of 4-1BBL was observed limiting its potential use as a single adjuvant for translation into a clinical vaccine.

Rational combinations of immunotherapeutics that target discrete pathways

An effective anti-tumor immune response requires the coordinated action of the innate and adaptive phases of the immune system. Critical processes include the activation of dendritic cells to present antigens, produce cytokines including type I interferons, and express multiple costimulatory ligands; induction of a productive T cell response within lymph nodes; migration of activated T cells to the tumor microenvironment in response to chemokines and homing receptor expression; and having effector T cells gain access to antigen-expressing tumor cells and maintain sufficient functionality to destroy them. However, tumors can become adept at escaping the immune response, developing multiple mechanisms to disrupt key processes. In general, tumors can be assigned into two different, major groups depending on whether the tumor there is an 'inflamed' or 'non-inflamed' tumor microenvironment. Improvements in our understanding of the interactions between the immune system and cancer have resulted in the development of various strategies to improve the immune-mediated control of tumors in both sub-groups. Categories of major immunotherapeutic intervention include methods to increase the frequency of tumor antigen-specific effector T cells in the circulation, strategies to block or uncouple a range of immune suppressive mechanisms within the tumor microenvironment, and tactics to induce de novo immune inflammation within the tumor microenvironment. The latter may be particularly important for eliciting immune recognition of non-inflamed tumor phenotypes. The premise put forth in this review is that synergistic therapeutic effects in vivo may be derived from combination therapies taken from distinct "bins" based on these mechanisms of action. Early data in both preclinical and some clinical studies provide support for this model. We also suggest that optimal application of these combinations may be aided by appropriate patient selection based on predictive biomarkers.

Enhanced function of cytotoxic T lymphocytes induced by dendritic cells modified with truncated PSMA and 4-1BBL

Interactions between costimulatory molecules and their receptors are vital for Ag-presenting dendritic cells (DCs) to initiate T cells activation, expansion and their antitumor immune responses. Augmentation of costimulatory signal due to the interaction of DCs and T cells may amplify, sustain and drive diversity of cytotoxic T lymphocytes (CTLs) and consequently enhance the antitumor response. 4-1BBL/4-1BB is such a pair of costimulatory ligand and receptor, playing an important role in the co-stimulation of CTLs. Previously, we demonstrated that DCs transduced with recombinant adenovirus encoding truncated PSMA (tPSMA) and m4-1BBL could induce prostate cancer regression in mouse models. In the present study, we further explored the adjuvant role of 4-1BBL in modulating CTLs activation induced by tPSMA gene-pulsed DCs. The apoptosis and cytotoxicity against tPSMA expressing RM-1 cells of CTLs were determined. Results showed that tPSMA gene-pulsed DCs effectively induced T lymphocyte activation and cytotoxicity, which was enhanced by upregulated expression of 4-1BBL, displaying better cell viability, lower CTLs apoptosis, higher expression anti-apoptotic protein of Bcl-xL and phosphorylation of P38, enhanced NF-κB activation, as well as more IFN-γ production. These results demonstrated that 4-1BBL may play a significant role in the co-stimulation pathway for Ag-presenting DCs-mediated CTLs activity, which might be a beneficial adjuvant factor for DCs-based cancer immunotherapy.

4-1BB protects dendritic cells from prostate cancer-induced apoptosis

It has been shown that human prostate cancer (PCa) cells induced apoptotic death of the most potent antigen-presenting cells, dendritic cells (DCs), which are responsible for the induction of specific antitumor immune responses. Here, we investigated the function of 4-1BB on protecting DCs from prostate cancer-induced apoptosis with an agonistic mAb to 4-1BB. RM-1 cells and DCs were co-incubated for 48 h and DC apoptosis was assessed by Annexin Vassay. TNF-α and IL-12 production were assessed by enzyme-linked immunosorbent assay (ELISA) and Bcl-2 and Bcl-xL on DCs were analyzed by Western blot. We have shown that co-incubation of RM-1 cells with DCs is accompanied by an increased level of DCs apoptosis. Triggering 4-1BB on DCs resulted in increased resistance of DCs to RM-1 cells-induced apoptosis, which was owing to the up-regulated expression of Bcl-2 and Bcl-xL, and increased secretion of TNF-αand IL-12. These results demonstrate that triggering 4-1BB on DCs could increased resistance of DCs to PCa-induced apoptosis.

Tumor-associated antigens for specific immunotherapy of prostate cancer

Prostate cancer (PCa) is the most common noncutaneous cancer diagnosis and the second leading cause of cancer-related deaths among men in the United States. Effective treatment modalities for advanced metastatic PCa are limited. Immunotherapeutic strategies based on T cells and antibodies represent interesting approaches to prevent progression from localized to advanced PCa and to improve survival outcomes for patients with advanced disease. CD8⁺ cytotoxic T lymphocytes (CTLs) efficiently recognize and destroy tumor cells. CD4⁺ T cells augment the antigen-presenting capacity of dendritic cells and promote the expansion of tumor-reactive CTLs. Antibodies mediate their antitumor effects via antibody-dependent cellular cytotoxicity, activation of the complement system, improving the uptake of coated tumor cells by phagocytes, and the functional interference of biological pathways essential for tumor growth. Consequently, several tumor-associated antigens (TAAs) have been identified that represent promising targets for T cell- or antibody-based immunotherapy. These TAAs comprise proteins preferentially expressed in normal and malignant prostate tissues and molecules which are not predominantly restricted to the prostate, but are overexpressed in various tumor entities including PCa. Clinical trials provide evidence that specific immunotherapeutic strategies using such TAAs represent safe and feasible concepts for the induction of immunological and clinical responses in PCa patients. However, further improvement of the current approaches is required which may be achieved by combining T cell- and/or antibody-based strategies with radio-, hormone-, chemo- or antiangiogenic therapy.

Exosomes as extrapulmonary signaling conveyors for nanoparticle-induced systemic immune activation

Evaluation of systemic biosafety of nanomaterials urgently demands a comprehensive understanding of the mechanisms of the undesirable interference and systemic signaling that arises between man-made nanomaterials and biological systems. It is shown that exosomes may act as signal conveyors for nanoparticle-induced systemic immune responses. Exosomes are extracellularly secreted membrane vesicles which act as Trojan horses for the dissemination and intercellular communication of natural nanosized particles (like viruses). Upon exposure to magnetic iron oxide nanoparticles (MIONs), it is possible to dose-dependently generate a significant number of exosomes in the alveolar region of BALB/c mice. These exosomes are quickly eliminated from alveoli into systemic circulation and largely transfer their signals to the immune system. Maturation of dendritic cells and activation of splenic T cells are significantly induced by these exosomes. Furthermore, exosome-induced T-cell activation is more efficient toward sensitized T cells and in ovalbumin (OVA)-sensitized mice than in the unsensitized counterparts. Activation of systemic T cells reveals a T helper 1 polarization and aggravated inflammation, which poses potential hazards to the deterioration of allergic diseases in OVA-sensitized mice. The studies suggest that exosomes may act as conveyors for extrapulmonary signal transduction in nanoparticle-induced immune systemic responses, which are the key in vivo processes of manufactured nanoparticles executing either biomedical functions or toxic responses.

Enhanced antitumor effects of a dendritic cell vaccine transfected with gastric cancer cell total RNA carrying the 4-1BBL gene in vitro

T cell-mediated antitumor immunity is a cellular immune response that requires two signals. The dendritic cell (DC) has been considered as the most efficient antigen-presenting cell (APC). It plays essential roles in the induction, regulation and maintenance of antitumor immunity in humans. The 4-1BB/4-1BB ligand (4-1BBL) pathway plays crucial roles in immune response, tumor immunity and autoimmune diseases through transduction of T cell co-stimulatory signals. The aim of this study was to generate the preparation protocol for a DC vaccine transfected with gastric cancer cell total ribonucleic acid (RNA) carrying the 4-1 BBL gene in vitro and to investigate its antitumor effects in murine forestomach carcinoma (MFC). The vaccine was prepared by transfecting MFC total RNAs carrying the 4-1BBL gene into the DCs that were isolated from 615 mouse bones. The T cell proliferation rate in the MFC/4-1BBL/DC group was higher than that in the DC group. The tumor cell kill rate in the MFC/4-1BBL/DC group was higher than that in the DC group. ELISA analysis showed that IL-12 and IFN-γ in the MFC/4-1BBL/DC group were more highly expressed compared to the other group. Collectively, our data demonstrate that the DC vaccine transfected with gastric cancer cell total RNA carrying the 4-1BBL gene has a stronger ability to kill gastric cancer cells through promoting T cell proliferation and enhancing the ability of cytotoxic T lymphocytes (CTLs) to kill gastric carcinoma cells and to secrete IL-12 and IFN-γ. Our results provide an effective therapeutic strategy for treating gastric cancer using a DC vaccine.

Gene carriers and transfection systems used in the recombination of dendritic cells for effective cancer immunotherapy

Dendritic cells (DCs) are the most potent antigen-presenting cells. They play a vital role in the initiation of immune response by presenting antigens to T cells and followed by induction of T-cell response. Reported research in animal studies indicated that vaccine immunity could be a promising alternative therapy for cancer patients. However, broad clinical utility has not been achieved yet, owing to the low transfection efficiency of DCs. Therefore, it is essential to improve the transfection efficiency of DC-based vaccination in immunotherapy. In several studies, DCs were genetically engineered by tumor-associated antigens or by immune molecules such as costimulatory molecules, cytokines, and chemokines. Encouraging results have been achieved in cancer treatment using various animal models. This paper describes the recent progress in gene delivery systems including viral vectors and nonviral carriers for DC-based genetically engineered vaccines. The reverse and three-dimensional transfection systems developed in DCs are also discussed.