Phenotypic Maturation Of Dendritic Cells Research Articles

Human umbilical cord blood derived serum and platelet-rich plasma can replace fetal bovine serum to induce human monocytes into dendritic cells

Introduction: Dendritic cell therapy is a promising therapeutic therapy for cancer. Various methods have been developed to culture and expand dendritic cells in vitro. However, most methods have used fetal bovine serum (FBS)-supplemented media to induce and expand monocytes; cells prepared by these methods cannot be used in the clinic. Therefore, this study aims to develop new methods to produce dendritic cells (DCs) from monocytes using serum-free medium. Methods: mononuclear cells (MNCs) were isolated from human umbilical cord blood by gradient centrifugation. They were then induced into DCs using 3 kinds of inducing media: M1 (medium supplemented with FBS), M2 (medium supplemented with human serum (HS) from umbilical cord blood), and M3 (medium supplemented with platelet-rich plasma (PRP) from umbilical cord blood) at 10% supplement. The MNCs were induced to immature DCs (iDCs) by granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin (IL)-4, and matured by tumor necrosis factor (TNF)-alpha. The phenotype of the DCs were evaluated by flow cytometry, immunohistochemistry, and in vitro phagocytic assay. Results: The results showed that all cells in the groups exhibited the shape of dendritic cells.Immunohistochemistry analysis showed that the mature cultured cells in the 3 kinds of media (i.e. supplemented with either FBS, HS, or PRP) were all CD86+HLA-DR+CD14-, representative of mature DC (mDC) phenotype. DCs cultured in HS and PRP media also exhibited FITC-Dextran phagocytosis and showed IL-12 gene expression similar to those DCs cultured in FBS medium. Conclusion: The results of the present study suggest that HS or PRP can replace FBS to produce DCs in vitro for clinical use.

Proteomic Identification of Heat Shock-Induced Danger Signals in a Melanoma Cell Lysate Used in Dendritic Cell-Based Cancer Immunotherapy.

Autologous dendritic cells (DCs) loaded with cancer cell-derived lysates have become a promising tool in cancer immunotherapy. During the last decade, we demonstrated that vaccination of advanced melanoma patients with autologous tumor antigen presenting cells (TAPCells) loaded with an allogeneic heat shock- (HS-) conditioned melanoma cell-derived lysate (called TRIMEL) is able to induce an antitumor immune response associated with a prolonged patient survival. TRIMEL provides not only a broad spectrum of potential melanoma-associated antigens but also danger signals that are crucial in the induction of a committed mature DC phenotype. However, potential changes induced by heat conditioning on the proteome of TRIMEL are still unknown. The identification of newly or differentially expressed proteins under defined stress conditions is relevant for understanding the lysate immunogenicity. Here, we characterized the proteomic profile of TRIMEL in response to HS treatment. A quantitative label-free proteome analysis of over 2800 proteins was performed, with 91 proteins that were found to be regulated by HS treatment: 18 proteins were overexpressed and 73 underexpressed. Additionally, 32 proteins were only identified in the HS-treated TRIMEL and 26 in non HS-conditioned samples. One protein from the overexpressed group and two proteins from the HS-exclusive group were previously described as potential damage-associated molecular patterns (DAMPs). Some of the HS-induced proteins, such as haptoglobin, could be also considered as DAMPs and candidates for further immunological analysis in the establishment of new putative danger signals with immunostimulatory functions.

Impact of 5-Fu/oxaliplatin on mouse dendritic cells and synergetic effect with a colon cancer vaccine.

The aim of the present study was to investigate the effects of 5-fluorouracil (5-Fu) and oxaliplatin on the function and activation pathways of mouse dendritic cells (DCs), and to clarify whether 5-Fu/oxaliplatin combined with the CD1d-MC38/α-galactosylceramide (α-GC) tumor vaccine exhibits synergistic effects on the treatment of colon cancer in mice. The combination of the Toll like receptor (TLR) ligands and/or 5-Fu/oxaliplatin was added into myeloid-derived DCs in vitro culture. DC phenotypic changes were detected by flow cytometry, and the secretion of DC cytokines was detected by cytometric bead array (CBA). A MC38 mouse colon cancer model was constructed and the DCs were isolated from the spleen, tumor tissue and lymph nodes following intraperitoneal injection of 5-Fu/oxaliplatin. The cell phenotypes were detected by flow cytometry. The tumor infiltrating leukocytes, splenocytes and lymph node cells were co-cultured with the dead MC38 tumor cells, and the secretion levels of interferon-γ (IFN-γ) were detected. 5-Fu/oxaliplatin combined with our previously developed CD1d-MC38/α-GC tumor vaccine was used to inhibit the growth of MC38 colon cancer in mice, and the tumor growth rate and survival time were recorded. 5-Fu/oxaliplatin exerted no significant effect on the expression of the stimulating phenotypes of DCs in vitro, while it could reduce the expression of programmed death ligand 1/2 (PD-L1/L2) and promote interleukin-12 (IL-12) secretion by DCs. Furthermore 5-Fu/oxaliplatin was beneficial to the differentiation of T-helper 1 (Th1) cells. 5-Fu/oxaliplatin further enhanced the stimulating phenotypic expression of DCs in tumor bearing mice, decreased PD-L1/L2 expression, and specifically activated the lymphocytes. The CD1d-MC38/α-GC tumor vaccine combined with 5-Fu/oxaliplatin could exert a synergistic role that resulted in a significant delay of the tumor growth rate, and an increase in the survival time of tumor bearing mice. 5-Fu/oxaliplatin decreased the expression of the DC inhibitory phenotypes PD-L1/L2, promoted DC phenotypic maturation in tumor bearing mice, activated the lymphocytes of tumor bearing mice, and exerted synergistic effects with the CD1d-MC38/α-GC colon cancer tumor vaccine.

Modulation of CD11c+ lung dendritic cells in respect to TGF‐β in experimental pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a deadly, progressive lung disease with very few treatment options till now. Bleomycin-induced pulmonary fibrosis (BIPF) is a commonly used mice model in IPF research. TGF-β1 has been shown to play a key role in pulmonary fibrosis (PF). Dendritic cell (DC) acts as a bridge between innate and adaptive immune systems. The coexistence of chronic inflammation sustained by mature DCs with fibrosis suggests that inflammatory phenomenon has key importance in the pathogenesis of pulmonary fibrosis. Here, we investigated the modulation of DCs phenotypic maturation, accumulation in lung tissue, and expression of other lung DC subsets in respect to TGF-β in PF. First, we established BIPF model in mice and blocked TGF-β expression by the use of inhibitor SB431542. Accumulation of lung CD11c+ DCs is significantly higher in both inflammatory and fibrotic phases of the disease but that percentages got reduced in the absence of TGF-β. TGF-β initiates up-regulation of costimulatory molecules CD86 and CD80 in the inflammatory phases of the disease but not so at fibrotic stage. Expression of lung DC subset CD11c+CD103+ is significantly increased in inflammatory phase and also in fibrotic phase of BIPF. Blocking of TGF-β causes decreased expression of CD11c+CD103+ DCs. Another important lung DC subset CD11c+CD11b+ expression is suppressed by the absence of TGF-β after bleomycin administration. CD11c+CD103+ DCs might have anti-inflammatory as well as anti-fibrotic nature in PF. All these data demonstrate differential modulation of CD11c+ lung DCs by TGF-β in experimental PF.

The cryo-thermal therapy-induced IL-6-rich acute pro-inflammatory response promoted DCs phenotypic maturation as the prerequisite to CD4+ T cell differentiation

In our previous studies, a novel tumour therapeutic modality of the cryo-thermal therapy has been developed leading to long-term survival in 4T1 murine mammary carcinoma model. The cryo-thermal therapy induced the strong acute inflammatory response and IL-6 was identified in an acute profile. In this study, we found that the cryo-thermal therapy triggered robust acute inflammatory response with high expression of IL-6 locally and systemically. The phenotypic maturation of dendritic cells (DCs) was induced by acute IL-6 following the treatment. The mature DCs promoted CD4+ T cell differentiation. Moreover, the production of interferon γ (IFN γ) in the serum and CD4+ T cells were both abrogated by IL-6 neutralisation following the treatment. Our findings revealed that the cryo-thermal therapy-induced acute IL-6 played an important role in initiating the cascading innate and adaptive anti-tumour immune responses, resulting in CD4+ T cell differentiation. It would be interesting to investigate acute IL-6 as an early indicator in predicating tumour therapeutic effect.

The immunoprotection of transplant mice allograft by suppressor of cytokine signaling 1 gene-modified dendritic cells induces T cell anergy

Objective To study the regulation of high expression of suppressor of cytokine signaling 1 (SOCS1) molecule in dendritic cells (DC), and to verify the effect of DC-SOCS1 on T cell function and allografts immune protective effects in vitro and in vivo. Methods DC were modified with high affinity replication-defective adenoviral vector Ad5F35 over-expressing SOCS1. The phenotype of transduced mature DC and the function were analyzed, and the mechanism of inducing donor-specific CD4+ T cells hyporesponsiveness was explored. The mouse allogenic islet transplantation model was established, and 24 h prior to transplantation each recipient mouse was given DC cells, DC-SOCS1 cells or equal amount of phosphate buffer (PBS), named DC group, DC-SOCS1 group and control group respectively. The survival of islet grafts of transplanted recipients was observed, and on the day 7 and the rejection day post transplantation, the islet graft glucose tolerance, pathological changes, the percentage of T cell subsets in the spleen and draining lymph nodes as well as related cytokines were observed. The possible associated mechanisms of SOCS1 gene-modified mature DC mitigating immune rejection and inducing transplant tolerance in vivo were explored. Results Genetic modified Ad5F35 dramatically increased the transduction efficiency of DC compared to regular Ad. The experimental data demonstrated there was a tendency that DC overexpressing SOCS1 can induce DC low down the express of MHC and costimulatory molecules, potentiate the ability of DC-SOCS1 to induce donor specific T cell anergy in mixed lymphocytes reaction (MLR) assay. DC-SOCS1 significantly prolonged the survival time of the islet allograft with a median survival time of (37.00±2.19) days, which is significantly longer than control [(20.00±0.55) d, P=0.008] and DC group [(10.00±0.45) d, P=0.001]. Flow cytometric analysis revealed that the DC-SOCS1 dramatically reduced the population of Th1 and Tc1 [(9.92±1.57)%, P=0.027], CD4 [(17.77±2.80)%, P=0.007] and CD8 [(14.92±2.18)%, P=0.004] in spleen lymphocytes compared to control group and DC group on day 7, and a reduction of CD4 [(26.00±2.02)%, P=0.034] was observed in draining lymph nodes compared to DC group. Conclusion SOCS1 genetic modification efficiently confers mDC with low express of MHC and costimulatory molecules, and allows them to induce T cell hyporesponsiveness in vitro. The DC-SOCS1 pretreated recipients exhibit immune tolerance and prolong islet allograft survival in vivo. Key words: Dendritic cells; Gene transduction; Suppressor of cytokine signaling 1; Islet transplantation; Immune tolerance

Immunomodulatory potential of Weissella cibaria JW15 on dendritic cells..

Abstract Lactic acid bacteria (LAB) are well-known to exert various beneficial health effects. Especially, immunomodulatory activities of LAB have been highlighted by recent studies. Our previous findings demonstrated that Weissella cibaria JW15 possessed immunostimulatory activities through modulation of macrophages, T cells and NK cells. Here, we studied whether this LAB is able to modulate dendritic cells (DC) function since DC are the most effective antigen presenting cells, linking innate immunity with adaptive immunity. Bone marrow derived dendritic cells (BMDCs) from mice were prepared and stimulated with live JW15, heat-killed JW15 and EPS isolated from JW15, followed by evaluation of cytokine production, expression of maturation markers and activation of intracellular signaling pathways. Our results revealed that JW15 as well as EPS induced phenotypic maturation of DC as shown by increased surface expression of CD80, CD86, CD40 and MHC II. In addition, both of JW15 and EPS increased the production of various cytokines in a dose dependent manner including TNF-a and IL-12. We also found that JW15 activated NF-κB and MAPK signal pathways. Collectively, we propose that JW15 and EPS isolated from this bacteria is able to activate dendritic cells and possess a potential to be developed as functional materials to boost immune system. Further studies are needed to provide comprehensive information to support our conclusions and reveal molecular mechanisms by which JW15 modulate immune responses.

Inhibitory Effects of Methanol Extract from Nardostachys chinensis on 27-hydroxycholesterol-induced Differentiation of Monocytic Cells

27-Hydroxycholesterol (27OHChol) has been reported to induce differentiation of monocytic cells into a mature dendritic cell phenotype. We examined the effect of methanol extract of Nardostachys chinensis (Nard) on 27OHChol-induced differentiation using THP-1, a human monocytic cell line. Treatment of monocytic cells with methanol extract of Nard resulted in decreased transcription and surface expression of CD80, CD83, and CD88 elevated by 27OHChol in a dose-dependent manner. Surface levels of MHC class I and II molecules elevated by 27OHChol were also reduced to basal levels by treatment with the Nard extract. Decreased endocytosis activity caused by 27OHChol was recovered by treatment with the Nard extract. CD197 expression and cell attachment were attenuated by the Nard extract. In addition, levels of transcription and surface expression of CD molecules involved in atherosclerosis, such as CD105, CD137, and CD166 upregulated by 27OHChol were significantly decreased by treatment with methanol extract of Nard. These results indicate that methanol extract of Nard down-regulates 27OHChol-induced differentiation of monocytic cells into a mature dendritic cell phenotype and expression of CD molecules associated with atherosclerosis. The current study suggests that biological activity of oxygenated cholesterol derivatives can be inhibited by herbal medication.

Glucose-Regulated Protein 78-Induced Myeloid Antigen-Presenting Cells Maintained Tolerogenic Signature upon LPS Stimulation.

The 78-kDa glucose-regulated protein (Grp78) is stress-inducible chaperone that mostly reside in the endoplasmic reticulum. Grp78 has been described to be released at times of cellular stress and as having extracellular properties that are anti-inflammatory or favor the resolution of inflammation. As antigen-presenting cells (APCs) play a critical role in both the priming of adaptive immune responses and the induction of self-tolerance, herein, we investigated the effect of Grp78 on the maturation of murine myeloid APCs (CD11c+ cells). Results showed that CD11c+ cells could be bound by AF488-labeled Grp78 and that Grp78 treatment induced a tolerogenic phenotype comparable to immature cells. Furthermore, when exposed to lipopolysaccharide, Grp78-treated CD11c+ cells (DCGrp78) did not adopt a mature dendritic cell phenotype. DCGrp78-primed T cells exhibited reduced proliferation along with a concomitant expansion of CD4+CD25+FoxP3+ cells in pancreaticoduodenal lymph nodes and induction of T cell apoptosis in vitro and ex vivo. The above work suggests that Grp78 is an immunomodulatory molecule that could aid resolution of inflammation. It may thus contribute to induce durable tolerance to be of potential therapeutic benefit in transplanted allogeneic grafts and autoimmune diseases such as type I diabetes.

Comparison of immunoregulatory effects of polysaccharides from three natural herbs and cellular uptake in dendritic cells

Polysaccharides from different types of natural herbs have not been compared with each other to determine their differential potencies on innate immune response, such as maturation of dendritic cells (DC). In addition, the role of endocytosis of polysaccharides in DC maturation has not been explored previously. Polysaccharides isolated from Astragalus membranaceus (APS), Ganoderma lucidum (GLP) and Radix ophiopogonis (OGP) were characterized and applied in bone marrow derived DC. Compared to immature DC, three polysaccharides with immunoactivities showed elongated dendrites, decreased phagocytic abilities, phenotypic changes (CD40/MHCII/CD80/CD86) and increased level of nitric oxide (NO) in a dose dependent manner. Interestingly, blockage of NO by iNOS inhibitor slightly decreased CD40 and MHCII but not CD80/CD86 expression induced by polysaccharides, indicating that NO was partially involved in DC maturation. In addition, GLP can enter cells in a dose and time dependent manner, shown as punctate distribution in the cytoplasm. Endocytic inhibitors sodium azide and brefeldinA that were demonstrated to inhibit cellular uptake of GLP can block phenotypic maturation of DC. Taken together, these results suggested that polysaccharides from natural herbs are effective immunostimulators with variable potencies ranking as GLP>APS>OGP, and the increase of NO level as well as the increase in polysaccharide endocytosis could be the novel strategies for improved innate response and immunotherapy.

Short-term MyD88 inhibition ameliorates cardiac graft rejection and promotes donor-specific hyporesponsiveness of skin grafts in mice.

Recognition of evolutionarily conserved ligands by Toll-like receptors (TLRs) triggers signaling cascades in innate immune cells to amplify adaptive immune responses. Nearly all TLRs require MyD88 to transduce downstream signaling. MyD88 deficiency has been shown to promote the allograft acceptance in mice. However, direct evidence for therapeutic potential of MyD88 inhibitors remains lacking. Herein, we used a MyD88 inhibitor, namely ST2825, to explore its therapeutic potential and mechanisms in fully allogeneic skin and heart transplant models. Phenotypic maturation of dendritic cells stimulated by TLR ligands was alleviated by ST2825 in parallel with reduced T-cell proliferation in vitro. A short-course treatment with ST2825 significantly prolonged cardiac graft survival (mean survival time = 18.5 ± 0.92 days vs. 7.25 ± 0.46 days). ST2825-treated group had significantly reduced proinflammatory cytokines in allografts compared with control group. ST2825 combined with anti-CD154 induced long-term skin allograft acceptance in about one-third of recipients (>100 days). 'Skin-tolerant' recipients showed attenuated donor-specific IFN-γ responses, intact IL-4 responses, and compromised alloantibody responses. We conclude that MyD88 inhibitor ST2825 attenuates acute cardiac rejection and promotes donor-specific hyporesponsiveness in stringent skin transplant models. The direct evidence suggests that pharmacological inhibition of MyD88 hold promising potential for transplant rejection.

Immunomodulation mediated by anti-angiogenic therapy improves viral vaccination against GL261 glioma tumors.

Abstract Glioblastoma multiforme (GBM) is a lethal cancer of the central nervous system with a median survival rate of 15 months with treatment. Thus, there is a critical need to develop novel therapies for GBM. Immunotherapy is emerging as a promising therapeutic strategy. However, current standard-of-care therapies for GBM, in particular anti-angiogenic therapies that block vascular endothelial growth factor (VEGF), may have undefined consequences on the efficacy of immunotherapy. While this treatment is primarily prescribed to reduce tumor vascularization, multiple immune cell types also express VEGF receptors, including the most potent antigen‑presenting cell, the dendritic cell (DC). Therefore, we assessed the role of anti-VEGF therapy in combination with a novel tumor antigen-specific picornaviral vaccination in the GL261 syngeneic murine model of glioma. We hypothesized that treatment of GL261 glioma-bearing mice with anti‑VEGF therapy will act synergistically with anti-tumor picornaviral vaccination by enhancing DC maturation. We found that VEGF blockade results in a more mature DC phenotype in the brain and tumor-draining lymph node, as demonstrated by an increase in the expression of the co‑stimulatory molecules B7-1 and B7-2. Furthermore, we observed an increase in brain infiltrating, tumor antigen-specific CD8 T cells. This change in immune response directly correlates with a significant reduction in tumor burden, as measured by bioluminescence imaging, and a significantly improved survival rate of mice receiving both anti-VEGF therapy and viral vaccination compared to either treatment alone. Thus, anti-angiogenic therapy can be used in conjunction with and enhance immunotherapy for GBM.

CD4 Receptor is a Key Determinant of Divergent HIV-1 Sensing by Plasmacytoid Dendritic Cells.

Plasmacytoid dendritic cells (pDC) are innate immune cells that sense viral nucleic acids through endosomal Toll-like receptor (TLR) 7/9 to produce type I interferon (IFN) and to differentiate into potent antigen presenting cells (APC). Engagement of TLR7/9 in early endosomes appears to trigger the IRF7 pathway for IFN production whereas engagement in lysosomes seems to trigger the NF-κB pathway for maturation into APC. We showed previously that HIV-1 (HIV) localizes predominantly to early endosomes, not lysosomes, and mainly stimulate IRF7 rather than NF-κB signaling pathways in pDC. This divergent signaling may contribute to disease progression through production of pro-apoptotic and pro-inflammatory IFN and inadequate maturation of pDCs. We now demonstrate that HIV virions may be re-directed to lysosomes for NF-κB signaling by either pseudotyping HIV with influenza hemagglutinin envelope or modification of CD4 mediated-intracellular trafficking. These data suggest that HIV envelope-CD4 receptor interactions drive pDC activation toward an immature IFN producing phenotype rather than differentiation into a mature dendritic cell phenotype.

Effect of calcineurin inhibition on phenotypic maturation of dendritic cells in an in-vitro model of invasive aspergillosis in lung transplant recipients

BackgroundInvasive aspergillosis in lung transplant recipients on immunosuppression has high morbidity and mortality. The calcineurin inhibitor FK506 inhibits the calcineurin–NFAT (nucleated factor of activated T cells) axis, which impairs the innate response to fungal infection. Immature dendritic cells (DCs) have a crucial immune signalling role by phagocytosing antigen, and then maturing and stimulating the T cell response. We investigated the effect of FK506 on phenotypic maturation of DCs in response to Aspergillus fumigatus infection. MethodsPeripheral blood mononuclear cells from healthy volunteers were negatively isolated by density gradient centrifugation (Ficoll, GE Healthcare, Amersham, UK) and were differentiated into DCs with molgramostim (GM-CSF) and interleukin 4. Day 5 cells were matured with interferon (IFN) γ. Day 7 cells were treated with FK506 or inoculated with swollen conidia of A fumigatus (multiplicity of infection 1:1). Cells were then stained with PE-bound anti-CD83 (a late maturation marker) and PerCP-Cy5.5-bound anti-CD209 (a DC-specific marker) and analysed by imaging flow cytometry (ImageStream, Amnis, Seattle, USA). Statistical analysis was performed with Graphpad Prism (version 6.0). Findings5000 cells per condition were analysed. The subset of DCs was identified by gating for CD209 positivity. We demonstrated upregulation of CD83 on the surface of DCs with IFNγ stimulation (26 228 mean fluorescence units [SE 1462] vs 12 534 [799], p<0·0001) A fumigatus infection of unstimulated DCs (29 888 [1393] vs 12 534 [799], p<0·0001), and A fumigatus infection of IFNγ-stimulated DCs (36 778 [1356] vs 26 228 [1462], p<0·0001). CD83 mean fluorescence intensity was reduced with FK506 treatment of IFNγ-stimulated DCs (26 228 [1462] vs 20 219 [846], p=0·0004), A fumigatus-infected unstimulated DCs (29 888 [1393] vs 24 289 [1253], p=0·0028), and A fumigatus-infected, IFN γ-stimulated DCs (36 778 [1356] vs 30 159 [1279], p=0·0004), but unchanged for unstimulated, uninfected DCs (12 534 [799] vs 11 942 [762], p=0·5921). InterpretationBoth A fumigatus infection and IFNγ stimulation promote phenotypic maturation of DCs in vitro, and treatment with FK506 inhibits maturation in this context. These findings suggest that FK506 has an inhibitory effect on innate antigen presentation to T cells and that it might impair the adaptive immune response to invasive aspergillosis in lung transplant recipients. FundingMedical Research Council Chain-Florey Clinical Research Fellowship.

Dexamethasone Suppresses Oxysterol-Induced Differentiation of Monocytic Cells.

Oxysterol like 27-hydroxycholesterol (27OHChol) has been reported to induce differentiation of monocytic cells into a mature dendritic cell phenotype. We examined whether dexamethasone (Dx) affects 27OHChol-induced differentiation using THP-1 cells. Treatment of monocytic cells with Dx resulted in almost complete inhibition of transcription and surface expression of CD80, CD83, and CD88 induced by 27OHChol. Elevated surface levels of MHC class I and II molecules induced by 27OHChol were reduced to basal levels by treatment with Dx. A decreased endocytosis ability caused by 27OHChol was recovered by Dx. We also examined effects of Dx on expression of CD molecules involved in atherosclerosis. Increased levels of surface protein and transcription of CD105, CD137, and CD166 by treatment with 27OHChol were significantly inhibited by cotreatment with Dx. These results indicate that Dx inhibits 27OHChol-induced differentiation of monocytic cells into a mature dendritic cell phenotype and expression of CD molecules whose levels are associated with atherosclerosis. In addition, we examined phosphorylation of AKT induced by 27OHChol and effect of Dx, where cotreatment with Dx inhibited the phosphorylation of AKT. The current study reports that Dx regulates oxysterol-mediated dendritic cell differentiation of monocytic cells.

Pore-formation by adenylate cyclase toxoid activates dendritic cells to prime CD8+ and CD4+ T cells.

The adenylate cyclase toxin-hemolysin (CyaA) of Bordetella pertussis is a bi-functional leukotoxin. It penetrates myeloid phagocytes expressing the complement receptor 3 and delivers into their cytosol its N-terminal adenylate cyclase enzyme domain (~400 residues). In parallel, ~1300 residue-long RTX hemolysin moiety of CyaA forms cation-selective pores and permeabilizes target cell membrane for efflux of cytosolic potassium ions. The non-enzymatic CyaA-AC(-) toxoid, has repeatedly been successfully exploited as an antigen delivery tool for stimulation of adaptive T-cell immune responses. We show that the pore-forming activity confers on the CyaA-AC(-) toxoid a capacity to trigger Toll-like receptor and inflammasome signaling-independent maturation of CD11b-expressing dendritic cells (DC). The DC maturation-inducing potency of mutant toxoid variants in vitro reflected their specifically enhanced or reduced pore-forming activity and K(+) efflux. The toxoid-induced in vitro phenotypic maturation of DC involved the activity of mitogen activated protein kinases p38 and JNK and comprised increased expression of maturation markers, interleukin 6, chemokines KC and LIX and granulocyte-colony-stimulating factor secretion, prostaglandin E2 production and enhancement of chemotactic migration of DC. Moreover, i.v. injected toxoids induced maturation of splenic DC in function of their cell-permeabilizing capacity. Similarly, the capacity of DC to stimulate CD8(+) and CD4(+) T-cell responses in vitro and in vivo was dependent on the pore-forming activity of CyaA-AC(-). This reveals a novel self-adjuvanting capacity of the CyaA-AC(-) toxoid that is currently under clinical evaluation as a tool for delivery of immunotherapeutic anti-cancer CD8(+) T-cell vaccines into DC.

Effects of Portulaca oleracea L. Polysaccharides on Phenotypic and Functional Maturation of Murine Bone Marrow Derived Dendritic Cells

Portulaca oleracea L. is an annual plant widely distributed from the temperate to the tropical zones. POL-P3b, a polysaccharide fraction purified from Portulaca oleracea L., is able to enhance immunity and inhibit tumor formation. Induction of antitumor immunity by dendritic-tumor fusion cells can be modulated by their activation status. Mature dendritic cells are significantly better than immature dendritic cells at cytotoxic T-lymphocyte induction. In this study, we analyzed the effects of POL-P3b on the maturation and function of murine bone-marrow-derived dendritic cells (DCs) and relevant mechanisms. The phenotypic maturation of DCs was confirmed by flow cytometry. We found that POL-P3b upregulated the expression of CD80, CD86, CD83, and major histocompatibility complex class II molecules on DCs, stimulated production of more interleukin (IL)-12, tumor necrosis factor-α, and less IL-10. Also, DCs pulsed POL-P3b and freeze-thaw antigen increased DCs-driven T cells' proliferation and promoted U14 cells' apoptosis. Furthermore, the expression of TLR-4 was significantly increased on DCs treated by POL-P3b. These results suggested that POL-P3b may induce DCs maturation through TLR-4. Taken together, our results may have important implications for the molecular mechanisms of immunopotentiation of POL-P3b, and provide direct evidence to suggest that POL-P3b should be considered as a potent adjuvant nutrient supplement for DC-based vaccines.

Enhanced growth suppression of TERT-positive tumor cells by oncolytic adenovirus armed with CCL20 and CD40L

Conditionally replicating adenoviruses (CRAds) selectively replicate in cancer cells and induce cell lysis, which represents a potential platform for cancer immunotherapy. The chemokine CCL20 exerts antitumor activity via chemoattraction of immature dendritic cells (DCs) and lymphocytes. However, the activation and maturation status of DCs is a limiting factor in the DCs -based immunity response. CD40L induces the phenotypic maturation of DCs, mediates DCs cytokine secretion, and increases the expression of FasL, which mediates apoptosis. We constructed a CCL20/CD40L co-expression CRAds (Ad-CCL20-CD40L) based on the AdEasy system. Ad-CCL20-CD40L was constructed from three plasmids, pGTE-CD40L, pShuttle-CMV-CCL20 and AdEasy-1, and was homologously recombined and propagated in the Escherichia coli strain BJ5183 and the packaging cell line HEK-293, respectively. Ad-CCL20-CD40L selectively replicates in TERT-positive tumor cells because the pGTE-CD40L plasmid contains the telomerase reverse transcriptase promoter (TERTp). Our results showed that Ad-CCL20-CD40L induced oncolytic effects and tumor-specific cytotoxicity of cytotoxic T lymphocytes (CTLs) in vitro. This study suggests that Ad-CCL20-CD40L can induce the antitumor immune response and that this platform can be modified to generate novel CRAds with other transgenes.

Murine Bone Marrow-Derived Dendritic Cells Transduced by Light-Helper-Dependent Herpes Simplex Virus-1 Amplicon Vector Acquire a Mature Dendritic Cell Phenotype.

Dendritic cells (DCs) turn into the most potent antigen-presenting cells following a complex transforming process, which leads to their maturation. Herpes simplex virus-1 (HSV-1) amplicon vectors represent highly versatile viral vector platforms with the ability to transduce immature DCs at exceedingly high efficiencies, while the efficiency of infection of mature DCs is significantly low. However, the bacterial artificial chromosome (BAC)-dependent (BD) amplicon vectors tested so far do not result in the maturation of mouse bone marrow-derived DCs (BMDCs) in vitro. In this study we investigated the effects of light-helper-dependent (LHD) amplicon vectors produced with the replication-defective HSV-1 LaLΔJ helper virus system. First, we observed that transgene expression in BMDC cultures was equally potent between the LHD and the BD amplicon vectors. We determined that the percentage of transduced cells and the duration of transgene expression were negatively influenced by the presence of increasing levels of helper virus. Second, infection by the LHD amplicon vector as well as the helper HSV-1 LaLΔJ virus alone resulted in the phenotypic maturation of BMDCs and the expression of both interferon-stimulated genes and proinflammatory cytokines. Further comparisons of the gene expression of infected DCs showed that while interferon-stimulated genes such as Ifit1, Ifit3, Mx2, Isg15, and Cxcl10 were induced by both BD and LHD amplicon vectors, early proinflammatory cytokine gene expression (Tnfa, Il1a, Il1b, Il6, Il10, Il12b, Cxcl1, and Cxcl16) and DC maturation were mediated only by the LHD amplicons.

Effects of Artemisia Absinthium L. Extract on the Maturation and Function of Dendritic Cells

Background: Artemisia absinthium L. (known as wormwood) is used as an antihelminthical, antimalarial, antiseptic, anti-inflammatory agent, and also in the treatment of gastric pain, in traditional medicine. Objectives: In the present study, we have evaluated the effects of the ethanolic extract of A. absinthium L. on the maturation and function of dendritic cells (DCs). Materials and Methods: The immunomodulatory effects of A. absinthium L. extract on DCs phenotypic maturation were determined by flow cytometry. The ability of the treated DCs to stimulate allogenic T cells proliferation and cytokines secretion was examined by mixed lymphocyte reaction (MLR) and enzyme-linked immuosorbent assay (ELISA), respectively. Results: A. absinthium L. extract showed that it could promote DCs phenotypic maturation by increasing the level of surface expression of CD40 as an important costimulatory marker on the DCs, compared to the control. Extract with concentration below 100 µg/mL significantly increased the production of interleukin (IL)-12 cytokine by DCs. The same 100 µg/mL concentration A. absinthium L. inhibited the proliferation of allogenic T cells and also significantly increased the level of IL-10 (P < 0.001). Moreover, the extract with concentrations below 100 µg/mL significantly increased production of interferon-γ (IFN-γ). Nevertheless, these changes were not significant for IL-4 production. Conclusions: Artemisia absinthium L. extract, at concentrations below 100 µg/mL, can modulate the immune response toward a Th1 pattern, by induction of CD40 expression on DCs and cytokine production. Also, it can inhibit DCs T cell stimulating activity, at high concentrations. Therefore, the traditional use of this plant possibly modulates immune-mediated disorders. However, future studies are needed to confirm these results.