Maturation State Of Dendritic Cells Research Articles

Immunomodulatory and antitumor effects of type I interferons and their application in cancer therapy.

During the last decades, the pleiotropic antitumor functions exerted by type I interferons (IFNs) have become universally acknowledged, especially their role in mediating interactions between the tumor and the immune system. Indeed, type I IFNs are now appreciated as a critical component of dendritic cell (DC) driven T cell responses to cancer. Here we focus on IFN-α and IFN-β, and their antitumor effects, impact on immune responses and their use as therapeutic agents. IFN-α/β share many properties, including activation of the JAK-STAT signaling pathway and induction of a variety of cellular phenotypes. For example, type I IFNs drive not only the high maturation status of DCs, but also have a direct impact in cytotoxic T lymphocytes, NK cell activation, induction of tumor cell death and inhibition of angiogenesis. A variety of stimuli, including some standard cancer treatments, promote the expression of endogenous IFN-α/β, which then participates as a fundamental component of immunogenic cell death. Systemic treatment with recombinant protein has been used for the treatment of melanoma. The induction of endogenous IFN-α/β has been tested, including stimulation through pattern recognition receptors. Gene therapies involving IFN-α/β have also been described. Thus, harnessing type I IFNs as an effective tool for cancer therapy continues to be studied.

Dendritic cells conditioned by activin A–induced regulatory T cells exhibit enhanced tolerogenic properties and protect against experimental asthma

Previously, we demonstrated that regulatory T(Treg) cells induced by the cytokine activin-A suppress TH2-mediated allergic responses and linked airway disease. Still, the effects of activin-A-induced regulatory T (Act-A-iTreg) cells on the regulation of dendritic cell (DC)-driven allergic inflammation remain elusive. Here we investigated whether Act-A-iTreg cells can modulate DC responses and endow them with enhanced tolerogenic functions. Using adoptive cell transfer studies in mouse models of allergic airway disease, we examined the effects of Act-A-iTreg cells on DC phenotype, maturation status, and TH2 cell priming potential. Genome-wide gene expression profiling characterized the transcriptional networks induced in tolerogenic DCs by Act-A-iTreg cells. The ability of DCs conditioned by Act-A-iTreg cells (Act-A-iTreg cell-modified DCs) to protect against experimental asthma, and the mechanisms involved were also explored. Act-A-iTreg cell-modified DCs exhibited a significantly impaired capacity to uptake allergen and stimulate naive and TH2 effector responses on allergen stimulation invivo accompanied by markedly attenuated inflammatory cytokine release in response to LPS. Gene-profiling studies revealed that Act-A-iTreg cells dampened crucial TH2-skewing transcriptional networks in DCs. Administration of Act-A-iTreg cell-modified DCs ameliorated cardinal asthma manifestations in preventive and therapeutic protocols through generation of strongly suppressive forkhead box P3+ Treg cells. Finally, programed death protein 1/programmed death ligand 1 signaling pathways were essential in potentiating the generation of DCs with tolerogenic properties by Act-A-iTreg cells. Our studies reveal that Act-A-iTreg cells instruct the generation of a highly effective immunoregulatory circuit encompassing tolerogenic DCs and forkhead box P3+ Treg cells that could be targeted for the design of novel immunotherapiesfor allergic disorders.

MicroRNA-155 is a master regulator of dendritic cell function in breast cancer

Abstract In anti-tumor immunity, dendritic cells (DCs) capture, process and present tumor antigens to T cells, and initiate a tumoricidal response. However, DCs are often found dysfunctional due to their exposure to the tumor microenvironment (TME), leading to tumor escape from immune surveillance. The mechanisms underlying the regulation or dysregulation of DC function in the context of tumor has not been well elucidated. Here a vital role of microRNA-155 (miR-155) in regulating the function of DCs in breast cancer is reported. miR-155 expression is closely correlated with the maturation status, migration ability and cytokine production of DCs, as well as their ability to activate T cells. We further demonstrate that miR-155 regulates DC migration through epigenetic modulation of CCR7 expression. Moreover, IL-6 and IL-10, two cytokines abundant in the TME, are found to impair DC maturation by suppressing miR-155 expression. Animal studies show that lack of miR-155 diminishes, while forced expression of miR-155 enhances, the effectiveness of DC-based immunotherapy for breast cancer. These findings suggest miR-155 is a master regulator of DC function in breast cancer, and boosting the expression of a single microRNA, miR-155, may significantly improve the efficacy of DC-based immunotherapies for breast cancer.

Slight Pro-Inflammatory Immunomodulation Properties of Dendritic Cells by Gardnerella vaginalis: The "Invisible Man" of Bacterial Vaginosis?

Bacterial vaginosis (BV), the most common genital infection in reproductive-aged women, is associated with increased risk of sexually transmitted infections. Its etiology remains unclear, especially the role of Gardnerella (G.) vaginalis, an anaerobic bacterium characteristic of the BV-alteration of the vaginal ecosystem. In the genital mucosa, dendritic cells (DCs) sense bacteria of the microenvironment via receptors and then orchestrate the immune response by induction of different T cell subtypes. We investigated the interactions between G. vaginalis and human monocyte-derived DCs using a wide range of bacterial concentrations (multiplicity of infection from 0.01 to 100), and the effects of this pathogen on PHA-induced lymphocyte proliferation. As observed by electron microscopy and cytometry, G. vaginalis reduced the internalization ability of DCs by forming extracellular clusters and induced neither DC maturation, nor DC secretion of cytokines, except at the highest dose with a very early DC maturation state. The same profile was observed on lymphocytes with significant increases of proliferation and cytokine secretion only at the highest bacterial concentration. Our findings indicate that G. vaginalis possesses slight immune-stimulating activities against DCs and T cells, reflecting thus a defective inflammatory response and giving rise to the atypical, non- or low-grade, inflammatory clinical disease profile.

Betalactam antibiotics affect human dendritic cells maturation through MAPK/NF-kB systems. Role in allergic reactions to drugs

The mechanisms leading to drug allergy in predisposed patients, especially those related to T-cell-mediated drug hypersensitivity, are not well understood. A key event in allergic reactions to drugs is the maturation process undergone by dendritic cells (DCs). Although amoxicillin (AX) has been reported to interact and maturate DCs from patients with AX-induced delayed-type hypersensitivity, the cell signaling pathways related to AX-mediated DC maturation have not been elucidated. We sought to determine the role of the MAPK and NF-κΒ pathways on AX-induced DC maturation and functional status. For that purpose, in monocyte-derived-DCs from AX-delayed allergic patients and tolerant subjects, we analyzed the activation pattern of p38MAPK, JNK, and ERK signaling and the NF-κB, maturation markers as well as endocytosis and allostimulatory capacities driven by AX-stimulated-DCs. Our data reveal that AX induces an increase in the phosphorylation levels of the three MAPKsand activated NF-κB in DCs from allergic patients. Moreover, the inhibition of these pathways prevents the up-regulation of surface molecules induced by AX. Additionally, we observed that the allostimulatory capacity and the endocytosis down-regulation in AX-stimulated-DCs from allergic patients depend on JNK and NF-κB activities. Taken together, our data shed light for the first time on the main signaling pathways involved in DC maturation from AX-delayed allergic patient.

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.

Heat-Shock Proteins 70 Induce Pro-Inflammatory Maturation Program in Decidual CD1a(+) Dendritic Cells.

The aim of the study was to assess possible binding of a mixture of constitutive Hsc70 and inducible Hsp70 forms (HSP70) to Toll-like receptor (TLR) 4 and CD91 receptors on decidual CD1a(+) dendritic cells (DCs) and their influence on DCs maturation status. Immunohistology and immunofluorescence of paraffin-embedded first trimetester and term pregnancy decidua were performed together with flow cytometry detection of antigens in DCs after stimulation of decidual mononuclear cells with HSP70. Hsc70 and Hsp70 labeling revealed intracellular and nuclear staining in trophoblast cells. The numbers of Hsc70(+) and Hsp70(+) cells of decidual tissue were higher in early pregnancy decidua than in decidua at term. HSP70 binds CD91 and TLR4 receptors on CD1a(+) DCs and increased the expression of CD83, HLA-DR, CD80, and CD86, but decreased CC receptor (CCR) 5. HSP70 increased CC ligand (CCL) 3 and CCL22. HSP70 in the concentration of 1 μg/mL increased the percentage of interferon-γ and interleukin (IL)-15-expressing cells over the cells expressing IL-4. HSP70 binds CD91 and TLR4 on decidual CD1a(+) DCs, causes their maturation, and increases IL-15 in the context of Th1 cytokine/chemokine domination, which could support immune response harmful for ongoing pregnancy.

Amnion-Derived Multipotent Progenitor Cells Inhibit Blood Monocyte Differentiation into Mature Dendritic Cells

Cells derived from the placenta have become the focus of extensive research concerning their ability to be used for regenerative medicine or cellular therapies. In a previous study, we characterized amnion-derived multipotent progenitor cells, or AMP cells, by in vitro methods and showed they were able to inhibit antigen-specific T-cell proliferation in a cell-to-cell contact-dependent fashion. Here we examine specific mechanisms involved in immunomodulation by AMP cells. We found that AMP cells significantly inhibited monocyte-derived myeloid dendritic cell (DC) maturation when placed in coculture. Cocultured monocytes retained the nondifferentiated macrophage marker CD14 while exhibiting significant reduction in DC maturation markers CD83 and CD1a, indicating an immature DC maturation state that is pivotal in determining its immune stimulatory or regulatory status. This effect was again dependent on cell-to-cell contact interaction. We also found a significant shift in cytokines present in the microenvironment of cocultures, which indicated a regulatory DC function rather than a stimulatory cell type. Here supernatants taken from AMP cell/monocyte cocultures yielded significant levels of regulatory cytokines, such as PGE2, IL-6, IL-10, and MIC-1. The soluble form of HLA-G was also found at higher levels in cocultures. In contrast, supernatants contained significantly less amounts of the T-cell-stimulating factor IL-12, which is normally produced by activated DCs. Interestingly, cocultured monocytes acquired significant expression of HLA-G on their cell surface over time. HLA-G has multifaceted immunological implications and may be a key molecule in influencing these cells to behave as regulatory DCs. Together, the influence of AMP cells on maturing DCs may favor a regulatory pathway that can be useful for therapeutic applications for immune-mediated disorders or transplantation therapies.

Modulation of dendritic cell immunobiology via inhibition of 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase.

The maturation status of dendritic cells determines whether interacting T cells are activated or if they become tolerant. Previously we could induce T cell tolerance by applying a 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase inhibitor (HMGCRI) atorvastatin, which also modulates MHC class II expression and has therapeutic potential in autoimmune disease. Here, we aimed at elucidating the impact of this therapeutic strategy on T cell differentiation as a consequence of alterations in dendritic cell function. We investigated the effect of HMGCRI during differentiation of peripheral human monocytes and murine bone marrow precursors to immature DC in vitro and assessed their phenotype. To examine the stimulatory and tolerogenic capacity of these modulated immature dendritic cells, we measured proliferation and suppressive function of CD4+ T cells after stimulation with the modulated immature dendritic cells. We found that an HMGCRI, atorvastatin, prevents dendrite formation during the generation of immature dendritic cells. The modulated immature dendritic cells had a diminished capacity to take up and present antigen as well as to induce an immune response. Of note, the consequence was an increased capacity to differentiate naïve T cells towards a suppressor phenotype that is less sensitive to proinflammatory stimuli and can effectively inhibit the proliferation of T effector cells in vitro. Thus, manipulation of antigen-presenting cells by HMGCRI contributes to an attenuated immune response as shown by promotion of T cells with suppressive capacities.

Application of antigen cross-presentation research into patient care.

EDITORIAL article Front. Immunol., 17 June 2014Sec. Antigen Presenting Cell Biology Volume 5 - 2014 | https://doi.org/10.3389/fimmu.2014.00287

RETRACTED: The rapid and sustained responses of dendritic cells to influenza virus infection in a non-human primate model

Dendritic cells (DCs) are readily infected by influenza viruses and play a crucial role in regulating host innate and adaptive immune responses to viral infection. The aims of this study are to characterize the dynamic changes in the numbers and maturation status of dendritic cells present in the lung and lung-associated lymph nodes (LALNs) in the model of a non-human primate (NHP) infected by influenza A virus (IAV). Cynomolgus macaques were infected with influenza A virus (H3N2) via bronchoscopy. Flow cytometry was used to analyze the DC numbers, maturation status and subsets during the time of acute infection (days 1, 2, 3, 4, 7) and the resolution phase (day 30). A dramatic increase in the numbers of influenza A virus-infected CD11c+CD14− myeloid dendritic cells (mDCs) and CD11c-CD123+ plasmacytoid dendritic cells (pDCs) were observed from day 1 to day 4 and peak up from day 7 post-infection. In lung and lung-associated lymph nodes, the numbers and maturation status of myeloid dendritic cells and plasmacytoid dendritic cells increased more slowly than those in the lung tissues. On day 30 post-infection, influenza A virus challenge increased the number of myeloid dendritic cells, but not plasmacytoid dendritic cells, compared with baseline. These findings indicate that dendritic cells are susceptible to influenza A virus infection, with the likely purpose of increasing mature myeloid dendritic cells numbers in the lung and lung and lung-associated lymph nodes, which provides important new insights into the regulation of dendritic cells in a non-human primate model.

The Role of Tumor/Dendritic Cell Interactions in the Regulation of Anti-Tumor Immunity: The Good, the Bad, and the Ugly

Since the discovery of dendritic cells (DCs) by Ralph Steinmanand Zanvil Cohn 40years ago (1), the role of these cells as criticalregulators of immune tolerance versus activation has emerged asone of the most fundamental concepts in the field of immunol-ogy. Serving as a link between the innate and adaptive immunesystems, DCs exhibit sensitive immune surveillance capabilitiesthat enable their acquisition of antigens from a variety of sourcesin peripheral tissues, and they possess unique sensory propertiesand antigen processing machinery that enable their transforma-tion into potent antigen-presenting cells (APCs). Importantly, theoutcome (immune tolerance versus activation) of antigen pre-sentation to T cells by DC is dependent on the maturation andactivation state of the DC, and significant efforts over the last 20CyearshavethereforefocusedonunderstandingfactorsthatregulateDC maturation and activation. While their role in self-toleranceand the activation of T cell immunity to foreign pathogens haslong been appreciated, more recently DCs have also been shownto play important roles in the regulation of anti-tumor immuneresponses. Since this time, considerable efforts have been placedon understanding many facets of tumor-associated DC,including:the induction, regulation, and maintenance of anti-tumor immu-nity by DC; tumor-associated interference with these processes tosubvert anti-tumor immunity; and the application of this knowl-edgetodeveloptherapeuticstrategiesforimprovingDC-mediatedanti-tumor immune responses. In this collection of articles, wehighlight our current understanding of the role played by DCin anti-tumor immunity and focus attention on important ques-tions that remain to be answered in the field as we aim to improvethe immunogenicity of tumor-associated DC and the outcome ofDC-mediated anti-tumor immune responses in the future.We begin this research topic with an Opinion article by RolfZinkernagel (2) and a responding Commentary from Anne Hos-malin (3), who offer opposing views on cross-presentation oftumor antigen by DC that we believe will generate interestingand thoughtful discussion. These articles are followed by a con-tribution from Schiavoni et al. (4) reviewing the major subsets ofDC that have been implicated in cross-presentation and the roleof type I IFN in enhancing DC-mediated cross-priming of anti-tumor CD8C T cell responses. Research topic co-editor KristianHargadon then reviews the various levels at which tumor cells,tumor-derived factors, and tumor-associated cells in the milieuof the tumor microenvironment can interfere with DC function(5). Mechanistic insights into tumor-altered differentiation of DCprecursors, tumor-associated suppression of DC maturation andactivation, and tumor-induced development of regulatory DCwith immunosuppressive function are highlighted, as are recentimmunotherapeutic strategies that have been designed to pre-vent or overcome tumor-associated DC dysfunction and enhancethe quality of anti-tumor immune responses. Co-editor Timo-thy Bullock further examines the metabolic changes that occurin DC during their maturation and discusses how dysregulatedmetabolism, particularly at the level of glycolysis and fatty acidmetabolism,intumor-associatedDCmayalsoimpedematurationand contribute to the diminished immune stimulatory functionof these cells (6). The impact of tumors on DC maturation isalso explored by Dudek et al. (7), who describe the complex-ity of DC maturation status in the context of tumors, wherethe typical dichotomy of immature versus mature DC that reg-ulate immune tolerance versus activation against clearly “self” or“non-self” antigen is less obvious. The authors describe a contin-uum of DC maturation states reported in the context of tumorsthat include not only the classical immature, tolerogenic DCand mature, immunogenic DC but also semi-mature DC whichexpress low or even moderate levels of costimulatory moleculesbut which produce minimal stimulatory cytokines and there-fore potentiate either tolerogenic or pro-tumorigenic responses.Studies that have identified factors (cytokines/chemokines, celldeath modalities, and cancer cell-derived danger signals) regulat-ing tumor-associated DC function are highlighted, as is the abilityof anti-cancer therapeutic agents to influence and modulate thematuration states of DC.Additional discussion of this topic is pro-videdbyOttandBhardwaj(8),whospeculatehowtumorcelldeathresulting from MAPK pathway inhibition might enhance cross-presentation by DC in BRAF

Differences in regulatory T-cell and dendritic cell pattern in decidual tissue of placenta accreta/increta cases

IntroductionPrimary infertility, miscarriage, and preeclampsia have been correlated with reduced numbers of regulatory T-cells (Treg) suggesting that decreased extravillous trophoblast (EVT) invasion originates from inadequate EVT tolerance. In contrast increased numbers of Treg-cells may be responsible for over-invasion of EVT. As the maturation status of dendritic cells (DC) influences T-cell behavior (tolerance or immune activation), altered relation between immature and mature DCs may also influence EVT invasion. MethodParaffin-embedded specimens of placenta accreta/increta (Pc; n = 11) and healthy intrauterine pregnancy (IUG; n = 18) were double-stained for cytokeratin and CD45, CD68, CD56, CD20, CD3, or CD8 as well as FoxP3/CD4 and FoxP3/CD8 and single-stained for CD4, CD25, FoxP3, CD209, Dec205 and CD83. Quantification of the leukocyte subpopulations was performed for decidua parietalis and basalis as characterized by cytokeratin-positive EVT. Statistical analysis was performed by using the Mann–Whitney test. ResultThere were significantly fewer CD4+ cells in Pc than in IUG. Concerning the Treg-markers, FoxP3+ cells are significantly increased. CD25+ cells showed a small non-significant increase in Pc in comparison to IUG. Concerning dendritic cells, immature non-activated CD209+ DCs were significantly decreased in Pc while immature activated CD205+ DCs were slightly but non-significantly increased. Mature activated CD83+ DC were non-significantly decreased in IUG vs Pc. Discussion and conclusionThe increased number of Treg-cells in Pc suggests significance for these cells in the regulation of trophoblast invasion. Their adequate interaction with other lymphocyte populations (e.g. adequately maturated dendritic cells) may be one mechanism to assure controlled EVT invasion.

Dendritic cells in childhood sepsis

PurposeOur aim was to investigate the level and the maturation status of dendritic cells (DCs) in pediatric patients with sepsis and its relation to prognosis. Materials and methodsThe study included 16 children with sepsis, 24 children with complicated sepsis, and 40 healthy control children. The patients were investigated within 24 hours of intensive care unit admission and after 28 days. Flow cytometric detection of DCs was done. ResultsWithin 24 hours, the levels of both plasmoid DCs and monocytoid DCs and the expression of CD86 and CD83 on DCs were significantly lower in patients than in controls, and the difference was marked in patients with complicated sepsis. The amount of CD86 and CD83 per cell was significantly lower in patients with complicated sepsis. The baseline numbers of monocytoid DCs and plasmoid DCs were higher in the survival patients than in nonsurvival patients. In addition, the expression of CD86 and CD83 on the entire DCs was significantly higher in the survival patients with sepsis. ConclusionSepsis is associated with reduced level of DCs and decreases their maturation. The estimation of DCs number and maturation state may be used as prognostic makers of sepsis.

Sustained Hyperresponsiveness of Dendritic Cells Is Associated with Spontaneous Resolution of Acute Hepatitis C

Some studies have reported that dendritic cells (DCs) may be dysfunctional in a subset of patients with chronic hepatitis C virus (HCV) infection. However, the function of DCs during acute HCV infection and their role in determining infectious outcome remain elusive. Here, we examined the phenotype and function of myeloid DCs (mDCs) and plasmacytoid DCs (pDCs) during acute HCV infection. Three groups of injection drug users (IDUs) at high risk of HCV infection were studied: an uninfected group, a group with acute HCV infection with spontaneous resolution, and a group with acute infection with chronic evolution. We examined the frequency, maturation status, and cytokine production capacity of DCs in response to the Toll-like receptor 4 (TLR4) and TLR7/8 ligands lipopolysaccharide (LPS) and single-stranded RNA (ssRNA), respectively. Several observations could distinguish HCV-negative IDUs and acute HCV resolvers from patients with acute infection with chronic evolution. First, we observed a decrease in the frequency of mature CD86(+), programmed death-1 receptor ligand-positive (PDL1(+)), and PDL2(+) pDCs. This phenotype was associated with the increased sensitivity of pDCs from resolvers and HCV-negative IDUs versus the group with acute infection with chronic evolution to ssRNA stimulation in vitro. Second, LPS-stimulated mDCs from resolvers and HCV-negative IDUs produced higher levels of cytokines than mDCs from the group with acute infection with chronic evolution. Third, mDCs from all patients with acute HCV infection, irrespective of their outcomes, produced higher levels of cytokines during the early acute phase in response to ssRNA than mDCs from healthy controls. However, this hyperresponsiveness was sustained only in spontaneous resolvers. Altogether, our results suggest that the immature pDC phenotype and sustained pDC and mDC hyperresponsiveness are associated with spontaneous resolution of acute HCV infection.

Glycodendrimers prevent HIV transmission via DC-SIGN on dendritic cells

Dendritic cells (DCs) are antigen-presenting cells efficient in capturing pathogens, and processing their antigenic determinants for presentation to antigen-specific T cells to induce robust immune responses. Their location at peripheral tissues and the expression of pattern-recognition receptors, among them DC-specific intercellular adhesion molecule-3-grabbing non-integrin (DC-SIGN), facilitates the capture of pathogens before spreading. However, some pathogens have developed strategies to escape the immune system. One of the most successful is HIV-1, which targets DC-SIGN for transport to the lymph node where the virus infects CD4(+) T cells. Contact of HIV-1 with DC-SIGN is thus the first event in the pathogenic cascade and, therefore, it is the primary target point for therapies aimed at HIV infection prevention. DC-SIGN recognizes specific glycans on HIV-1 and this interaction can be blocked by competitive inhibition through glycans. Although the affinity of glycans is relatively low, multivalency may increase avidity and the strength to compete with HIV-1 virions. We have designed multivalent dendrimeric compounds based on Lewis-type antigens that bind DC-SIGN with high selectivity and avidity and that effectively block gp120 binding to DC-SIGN and, consequently, HIV transmission to CD4(+) T cells. Binding to DC-SIGN and gp120 inhibition was higher on glycodendrimers with larger molecular diameter, indicating that the geometry of the compounds is an important factor determining their functionality. Our compounds elicited DC-SIGN internalization, a property of the receptor upon triggering, but did not affect the maturation status of DCs. Thus, Le(X) glycodendrimers could be incorporated into topic prophylactic approaches for the prevention of HIV-1 transmission.

Assessment of maturation status of tumor-infiltrating dendritic cells in invasive ductal carcinoma of the breast: relation with vascular endothelial growth factor expression

Poor immunogenicity has been described in breast carcinoma although dendritic cells, the major antigen presenters, are known to infiltrate the tumor. Vascular endothelial growth factor has been proposed to reduce local immune response in tumors. We investigated the maturation status of dendritic cells in invasive ductal carcinoma of the breast in relation to vascular endothelial growth factor expression and clinicopathological parameters. Fifty invasive ductal carcinomas of the breast were immunostained with CD1a (marker of immature dendritic cells); CD83 (marker of mature dendritic cells), vascular endothelial growth factor, estrogen receptor and progesterone receptor. Mature dendritic cells were detected in 36 cases (72%), and correlated with smaller tumor size, negative lymph nodes, positive steroid receptor status, and lower grade (P < 0.001). Immature dendritic cells were found in 100% of cases and correlated only with negative steroid receptor expression (estrogen receptor and progesterone receptor) (P=0.006 and 0.020 respectively). Vascular endothelial growth factor expression was detected in 44 cases (88%), and correlated directly with positive nodal metastases (P=0.014), correlated inversely with mature dendritic cell count (P=0.005); and did not correlate with immature dendritic cell count (P=0.104). Mature dendritic cell count correlates with good prognostic features in invasive ductal carcinoma of the breast, suggesting their role in initiating primary anti-tumor immune response. Vascular endothelial growth factor expression may play a role in inhibition of dendritic cell maturation sequence in the tumor microenvironment.

Immature, Semi-Mature, and Fully Mature Dendritic Cells: Toward a DC-Cancer Cells Interface That Augments Anticancer Immunity

Dendritic cells (DCs) are the sentinel antigen-presenting cells of the immune system; such that their productive interface with the dying cancer cells is crucial for proper communication of the “non-self” status of cancer cells to the adaptive immune system. Efficiency and the ultimate success of such a communication hinges upon the maturation status of the DCs, attained following their interaction with cancer cells. Immature DCs facilitate tolerance toward cancer cells (observed for many apoptotic inducers) while fully mature DCs can strongly promote anticancer immunity if they secrete the correct combinations of cytokines [observed when DCs interact with cancer cells undergoing immunogenic cell death (ICD)]. However, an intermediate population of DC maturation, called semi-mature DCs exists, which can potentiate either tolerogenicity or pro-tumorigenic responses (as happens in the case of certain chemotherapeutics and agents exerting ambivalent immune reactions). Specific combinations of DC phenotypic markers, DC-derived cytokines/chemokines, dying cancer cell-derived danger signals, and other less characterized entities (e.g., exosomes) can define the nature and evolution of the DC maturation state. In the present review, we discuss these different maturation states of DCs, how they might be attained and which anticancer agents or cell death modalities (e.g., tolerogenic cell death vs. ICD) may regulate these states.

Generation of large numbers of highly purified dendritic cells from bone marrow progenitor cells after co-culture with syngeneic murine splenocytes

Dendritic cells (DCs) are called the sentinels of the human immune system because of their function as antigen presenting cells (APCs) that elicit a protective immune response. Given that DCs have been used for many years as target cells in a great number of experiments, it became essential to devise a new method for producing DCs in higher quantities and of greater purity. Here we report a novel technique for obtaining more dendritic cells, and with higher purity, from in-vitro co-culture of bone marrow (BM) cells with splenocytes.From a total of 20×106 BM cells and 120×106splenocytes, 3×106 BM cells along with 20×106splenocytes were co-cultured in petri dishes for DC generation; 120×106 splenocytes from one C57BL/6 mouse were also co-cultured in petri dishes for DC generation. BM cells were the control group cultured in the same conditions except for the presence of splenocytes. Purity and maturation state of DCs were checked by lineage surface markers (CD11c, CD11b, CD8α, and F4/80) and the expression levels of MHCII as well as co-stimulatory molecules (CD86, CD80, and CD40). Endocytosis and thymidine uptake capacity were also used to test the functionality of DCs. The levels of IL-12p70, IL-23, and IL-10 were also checked in the supernatant of cultured cells by ELISA.The number of DCs derived from co-culture of BM and splenocytes (DCsTME) was at least twice that of BM-derived DCs in the absence of splenocytes. In addition, the purity of DCs after co-culture of BM and splenocytes was greater than that of DCs in the control culture (90.2% and 77.2%, respectively; p<0.05). While functional assays showed no differences between co-culture and control groups, IL-10 levels were significantly lower in DCsTME compared to BM-derived DCs in the absence of splenocytes (193pg/ml and 630pg/ml, respectively; p<0.05).The results of the present study show that the generation of DCs from BM progenitors is accelerated in the presence of syngeneic splenocytes. Given the larger number of generated DCs, and with higher purity, in this technique, DCsTME could be more advantageous for DC-based immunotherapy and vaccination techniques.

Absence of LTB4/BLT1 axis facilitates generation of mouse GM-CSF–induced long-lasting antitumor immunologic memory by enhancing innate and adaptive immune systems

AbstractBLT1 is a high-affinity receptor for leukotriene B4 (LTB4) that is a potent lipid chemoattractant for myeloid leukocytes. The role of LTB4/BLT1 axis in tumor immunology, including cytokine-based tumor vaccine, however, remains unknown. We here demonstrated that BLT1-deficient mice rejected subcutaneous tumor challenge of GM-CSF gene-transduced WEHI3B (WGM) leukemia cells (KO/WGM) and elicited robust antitumor responses against second tumor challenge with WEHI3B cells. During GM-CSF–induced tumor regression, the defective LTB4/BLT1 signaling significantly reduced tumor-infiltrating myeloid-derived suppressor cells, increased the maturation status of dendritic cells in tumor tissues, enhanced their CD4+ T-cell stimulation capacity and migration rate of dendritic cells that had phagocytosed tumor-associated antigens into tumor-draining lymph nodes, suggesting a positive impact on GM-CSF–sensitized innate immunity. Furthermore, KO/WGM mice displayed activated adaptive immunity by attenuating regulatory CD4+ T subsets and increasing numbers of Th17 and memory CD44hiCD4+ T subsets, both of which elicited superior antitumor effects as evidenced by adoptive cell transfer. In vivo depletion assays also revealed that CD4+ T cells were the main effectors of the persistent antitumor immunity. Our data collectively underscore a negative role of LTB4/BLT1 signaling in effective generation and maintenance of GM-CSF–induced antitumor memory CD4+ T cells.