Blood Dendritic Cells Research Articles

Use of PD-L1 and ICOSL to discriminate innate and adaptive dendritic cells in the head and neck cancer microenvironment.

e14184 Background: Inflamed head and neck squamous cell carcinomas (HNSCC), have a better prognosis independently of the treatment modalities, and have an increased response rate to PD(L)1 blockade. Dendritic cells (DC) infiltration is associated to T cell infiltration and DC are critical in the immune response to cancer, but little is known on HNSCC infiltrating DC. The objectives were to determine the differences between DC infiltrating inflamed vs non inflamed tumors, to understand which mechanisms modulate DC phenotypes and which are the associated functions. Methods: 22 untreated HNSCC were characterized by flow cytometry for their immune infiltrate. RNA sequencing of sorted tumor infiltrating myeloid subsets and blood DC were analyzed for differentially expressed genes. The TMod database (Grandclaudon et al.), testing the effect of various stimuli on DC and subsequently on co-cultured T cells, was used to decipher DC and T cell modulation. Results: The level of CD3 infiltration was positively associated to the level of DC infiltration and PDL1 expression on myeloid cells, and negatively to the level neutrophils and of ICOSL expression on myeloid cells. PDL1high ICOSLneg DC from inflamed tumors were matched with the “innate DC” phenotype described in vitro, highly efficient at secreting cytokines and chemokines but poorly activating naïve CD4 T cells. DC from non-inflamed tumor resembled immature medium DC. A third type of DC, “adaptive DC”, expressing high levels of ICOSL and low of PDL1, poorly efficient at cytokine and chemokine secretion, but highly efficient at activating T cells is was described in vitro, but not found in tumors. RNAseq analysis confirmed this innate polarization and highlighted that those cells present a mature and NFkB activated phenotype. Conclusions: Inflamed HNSCC contain stimuli able to induce the recruitment and the differentiation of DC into mature, NFkB activated “innate” DC, highly efficient at secreting cytokines and chemokines but poorly activating naïve CD4 T cells. These data partly explain the superiority of CPS over TPS for the prediction of response to PD(L)1 blockade. More importantly, the stimuli identified here may be used as adjuvants to induce this DC « innate » maturation in non-inflamed tumors, but should only be used in combination with anti-PD(L)1 immunotherapy.

Strength and medium-term impact of HisAK70 immunization in dogs: Vaccine safety and biomarkers of effectiveness for ex vivo Leishmania infantum infection

HisAK70 candidates have successfully been tested in cutaneous (CL) and visceral leishmaniosis (VL) mouse models. Here, we analyse different biomarkers in dog trials after a heterologous immunization strategy with a HisAK70 candidate (plasmid DNA plus adoptive transfer of peripheral blood-derived dendritic cells (DCs) pulsed with the same pathoantigen and CpG ODN as an adjuvant) to explore the antileishmanial activity in an ex vivo canine co-culture system in the presence of Leishmania infantum parasites. In the canine model, the heterologous HisAK70 vaccine could decrease the infection index in the DC-T cell co-culture system by up to 54% after 30 days and reach almost 67% after 100 days post-immunization, respectively, compared to those obtained in the control group of dogs. The observed security and potential to fight ex vivo L. infantum infection highlight a HisAK70 heterologous immunization strategy as a promising alternative to evaluate its effectiveness against canine VL.

Role of B7-H4 in the Progression and Prognosis of Cervical Inflammation to Cancer After Human Papilloma Virus Infection.

The immune checkpoint molecule B7-H4 is highly expressed in various types of cancer, but little is known about its role in the development of cervical lesions associated with human papilloma virus (HPV). This study aimed to investigate the role of B7-H4 in cervical lesion progression and the relationship between B7-H4 and HPV infection. This was a retrospective study of tissue samples from 30 patients with cervical cancer, 28 with cervical intraepithelial neoplasia (CIN), and 75 with cervical inflammatory lesions. Serum-soluble B7-H4 (sB7-H4) was assessed by ELISA. Tissue B7-H4 expression was measured by RT-PCR and immunochemistry. Expression of B7-H4 in dendritic cells was assessed by flow cytometry. sB7H4 increased gradually from the patients with cervical inflammation to patients with cervical cancer and decreased after treatment. sB7-H4 had a diagnostic value in cervical intraepithelial neoplasia (CIN (area under the curve (AUC) = 0.8929) and cervical cancer (AUC = 0.9545). B7-H4 expression in inflammatory cervical tissue and peripheral blood dendritic cells (DCs) increased gradually from inflammation to cancer (P < 0.001). sB7-H4 was positively associated with B7-H4 expression in cervical tissue and DCs and with the frequency of CD4+CD25+Foxp3+ regulatory T cells (P < 0.001). The level of sB7-H4, and tissue and DC B7-H4 expression were associated with HPV infection (P < 0.001). These data strongly support the use of sB7-H4 for monitoring the progression of cervical cancer associated with HPV, and for evaluating the immune status of the patients.

GMP-compliant sorting of dendritic cells for CCR7 expression improves therapeutic efficacy in cancer by enhancing lymph node migration and antigen-specific T cell activation

Background & Aim Dendritic cells (DCs) are a potentially powerful cell therapy due to their ability to induce T cell activation to defined antigens; however, this potential has not yet been realised in clinical trials. Monocyte-derived DCs (moDCs) are most commonly used in cancer therapy, although the rare blood DC subsets have also been explored. Crucially, cell function requires the chemokine receptor CCR7, which guides DCs from the site of antigen uptake to the lymph nodes. CCR7 expression, and therefore migration, is variable after isolation of DCs from blood or ex vivo culture, and may account for the limited efficacy seen in clinical trials. We hypothesised that selection of CCR7+ DCs by sorting would to improve cell function and therapeutic use of DCs. Methods, Results & Conclusion We have previously shown that murine CCR7+ bone marrow DCs (BMDCs) can be sorted using a novel chemokine-based system and show enhanced lymph node migration. This CCL19-fluorophore construct was shown to also detect expression of CCR7 on human DCs, and significantly enrich CCR7+ cells to high purity and viability (>90%) using magnetic bead and fluorescence-based sorting methods. Both murine and human CCR7+ DCs were more mature than CCR7- DCs by expression of CD80 and CD86 and production of T cell chemoattractants such as CCL17 and CCL22. In vitro, CCR7+ DCs were also most effective in stimulating antigen-specific T cells, especially memory T cells producing IFNγ, TNFα and IL-2. In vivo, sorted murine CCR7+ BMDCs, but not unsorted DCs, were sufficient to reduce subcutaneous and metastatic tumour growth in the B16F10.ova mouse model. Increased migration of injected DCs to lymph nodes led to an elevated overall number of tumour-specific T cells in CCR7+ DC-receiving mice, but this was not seen in those receiving unsorted DCs. In agreement with in vitro data, CCR7+ DCs increased production of mature tumour-specific T cells, particularly with the desirable memory (CD62L+CD44+) phenotype, suggesting their potency in a human therapeutic context. As production of this chemokine construct is possible at GMP grade, this protocol is amenable to GMP translation using the MACSQuant Tyto cell sorter. Purity and viability of CCR7+ DCs remained consistently high between the original and GMP-ised protocols, with an improved cell yield versus bead sorting. Overall, this novel sorting process is compliant with current GMP manufacture and creates a realistic DC product with enhanced function and potential therapeutic benefit.

Replicating Adenovirus-SIV Immunization of Rhesus Macaques Induces Mucosal Dendritic Cell Activation and Function Leading to Rectal Immune Responses.

Inducing strong mucosal immune responses by vaccination is important for providing protection against simian immunodeficiency virus (SIV). A replicating adenovirus type 5 host range mutant vector (Ad5hr) expressing SIV proteins induced mucosal immune responses in rectal tissue associated with delayed SIV acquisition in female rhesus macaques, but the initial mechanisms leading to the induced immunity have not been elucidated. As dendritic cells (DCs) are known to orchestrate both innate and adaptive effector immune cell responses, we investigated their role here. Rhesus macaques were immunized twice mucosally with a replicating Ad5hr expressing SIV Env, Gag, and Nef (Ad-SIV) or empty Ad5hr vector (Ad-Empty). DC subsets and their activation were examined in rectal tissue, blood, and LNs at 3 timepoints after each immunization. Plasmacytoid DCs, myeloid DCs, and Langerhans cells were significantly increased in the rectal mucosa, but only myeloid DCs were significantly increased in blood post-immunizations. All rectal DC subsets showed increased frequencies of cells expressing activation markers and cytokines post-immunization, blood DCs showed mixed results, and LN DCs showed few changes. Rectal DCs responded strongly to the vector rather than expressed SIV antigens, but rectal DC frequencies positively correlated with induced rectal antigen-specific memory T and B cells. These correlations were confirmed by in vitro co-cultures showing that rectal Ad-SIV DCs induced proliferation and antigen-specific cytokine production by autologous naïve T cells. Our results highlight the rapid response of DCs to Ad immunization and their role in mucosal immune activation and identify initial cellular mechanisms of the replicating Ad-SIV vaccine in the rhesus macaque model.

In Vitro Generation of Anti-Osteosarcoma Cytotoxic Activity Using Dendritic Cells Loaded with Heat Shock Protein 70-Peptide Complexes

Introduction: This study aimed at evaluating the anti-osteosarcoma activity of cytotoxic T lymphocytes (CTLs) induced by dendritic cells (DCs) pulsed with heat shock protein 70-peptide complexes (Hsp70-PCs). Materials and methods: Human recombinant Hsp70 expression was analyzed using thin layer scanning and Western blot assay. Tumor antigens from Saos-2 cells were extracted to reconstitute Hsp70-PCs. Maturation of cord blood-derived DC was evaluated by alkaline phosphatase-anti-alkaline phosphatase kit and inverted microscope. The anti-osteosarcoma activity of CTLs evoked by DCs loaded with Hsp70-PCs was determined using Thiazolyl Blue Tetrazolium Bromide (MTT) assay. Results: Hsp70 protein level in BL21 (DE3) increased in a time-dependent manner after induction. The expression of surface markers was upregulated and a typical dendritic morphology was observed in mature DCs. Allogeneic CTLs exhibited strong cytotoxic activity against Saos-2 cells. Conclusion: Our in vitro experiment demonstrated the potent induction of cytotoxic activity against osteosarcoma using DC-based vaccine loaded with Hsp70-PCs.

Association of Dendritic Cell Signatures With Autoimmune Inflammation Revealed by Single-Cell Profiling.

To identify single-cell transcriptional signatures of dendritic cells (DCs) that are associated with autoimmunity, and determine whether those DC signatures are correlated with the clinical heterogeneity of autoimmune disease. Blood-derived DCs were single-cell sorted from the peripheral blood of patients with rheumatoid arthritis, systemic lupus erythematosus, or type 1 diabetes as well as healthy individuals. DCs were analyzed using single-cell gene expression assays, performed immediately after isolation or after in vitro stimulation of the cells. In addition, protein expression was measured using fluorescence-activated cell sorting. CD1c+ conventional DCs and plasmacytoid DCs from healthy individuals exhibited diverse transcriptional signatures, while the DC transcriptional signatures in patients with autoimmune disease were altered. In particular, distinct DC clusters, characterized by up-regulation of TAP1, IRF7, and IFNAR1, were abundant in patients with systemic autoimmune disease, whereas DCs from patients with type 1 diabetes had decreased expression of the regulatory genes PTPN6, TGFB, and TYROBP. The frequency of CD1c+ conventional DCs that expressed a systemic autoimmune profile directly correlated with the extent of disease activity in patients with rheumatoid arthritis (Spearman's r = 0.60, P = 0.03). DC transcriptional signatures are altered in patients with autoimmune disease and are associated with the level of disease activity, suggesting that immune cell transcriptional profiling could improve our ability to detect and understand the heterogeneity of these diseases, and could guide treatment choices in patients with a complex autoimmune disease.

Human Blood and Tonsil Plasmacytoid Dendritic Cells Display Similar Gene Expression Profiles but Exhibit Differential Type I IFN Responses to Influenza A Virus Infection.

Influenza A virus (IAV) infection constitutes an annual health burden across the globe. Plasmacytoid dendritic cells (PDCs) are central in antiviral defense because of their superior capacity to produce type I IFNs in response to viruses. Dendritic cells (DCs) differ depending on their anatomical location. However, only limited host-pathogen data are available from the initial site of infection in humans. In this study, we investigated how human tonsil PDCs, likely exposed to virus because of their location, responded to IAV infection compared with peripheral blood PDCs. In tonsils, unlike in blood, PDCs are the most frequent DC subset. Both tonsil and blood PDCs expressed several genes necessary for pathogen recognition and immune response, generally in a similar pattern. MxA, a protein that renders cells resistant to IAV infection, was detected in both tonsil and blood PDCs. However, despite steady-state MxA expression and contrary to previous reports, at high IAV concentrations (typically cytopathic to other immune cells), both tonsil and blood PDCs supported IAV infection. IAV exposure resulted in PDC maturation by upregulation of CD86 expression and IFN-α secretion. Interestingly, blood PDCs secreted 10-fold more IFN-α in response to IAV compared with tonsil PDCs. Tonsil PDCs also had a dampened cytokine response to purified TLR ligands compared with blood PDCs. Our findings suggest that tonsil PDCs may be less responsive to IAV than blood PDCs, highlighting the importance of studying immune cells at their proposed site of function.

Modulation of SPARC/Hevin Proteins in Alzheimer's Disease Brain Injury.

Alzheimer’s disease (AD) is an age-related progressive form of dementia that features neuronal loss, intracellular tau, and extracellular amyloid-β (Aβ) protein deposition. Neurodegeneration is accompanied by neuroinflammation mainly involving microglia, the resident innate immune cell population of the brain. During AD progression, microglia shift their phenotype, and it has been suggested that they express matricellular proteins such as secreted protein acidic and rich in cysteine (SPARC) and Hevin protein, which facilitate the migration of other immune cells, such as blood-derived dendritic cells. We have detected both SPARC and Hevin in postmortem AD brain tissues and confirmed significant alterations in transcript expression using real-time qPCR. We suggest that an infiltration of myeloid-derived immune cells occurs in the areas of diseased tissue. SPARC is highly expressed in AD brain and collocates to Aβ protein deposits, thus contributing actively to cerebral inflammation and subsequent tissue repair, and Hevin may be downregulated in the diseased state. However, further research is needed to reveal the exact roles of SPARC and Hevin proteins and associated signaling pathways in AD-related neuroinflammation. Nevertheless, normalizing SPARC/Hevin protein expression such as interdicting heightened SPARC protein expression may confer a novel therapeutic opportunity for modulating AD progression.

Inference of Cellular Immune Environments in Sputum and Peripheral Blood Associated with Acute Exacerbations of COPD.

Chronic obstructive pulmonary disease (COPD) is the fourth leading cause of death in the United States, with high associated costs. Most of the cost burden results from acute exacerbations of COPD (AE-COPD), events associated with heightened symptoms and mortality. Cellular mechanisms underlying AE-COPD are poorly understood, likely because they arise from dysregulation of complex immune networks across multiple tissue compartments. To gain systems-level insight into cellular environments relevant to exacerbation, we applied data-driven modeling approaches to measurements of immune factors (cytokines and flow cytometry) measured previously in two different human tissue environments (sputum and peripheral blood) during the stable and exacerbated state. Using partial least squares discriminant analysis, we identified a unique signature of cytokines in serum that differentiated stable and AE-COPD better than individual measurements. Furthermore, we found that models integrating data across tissue compartments (serum and sputum) trended towards being more accurate. The resulting paracrine signature defining AE-COPD events combined elevations of proteins associated with cell adhesion (sVCAM-1, sICAM-1) and increased levels of neutrophils and dendritic cells in blood with elevated chemoattractants (IP-10 and MCP-2) in sputum. Our results supported a new hypothesis that AE-COPD is driven by immune cell trafficking into the lung, which requires expression of cell adhesion molecules and raised levels of innate immune cells in blood, with parallel upregulated expression of specific chemokines in pulmonary tissue. Overall, this work serves as a proof-of-concept for using data-driven modeling approaches to generate new insights into cellular processes involved in complex pulmonary diseases.

Hepatocellular carcinoma-associated antigen 59 of Haemonchus contortus modulates the functions of PBMCs and the differentiation and maturation of monocyte-derived dendritic cells of goats in vitro

BackgroundHepatocellular carcinoma-associated antigen 59 (HCA59), which is one of the most important excretory/secretory products of Haemonchus contortus (HcESPs), is known to have antigenic functions. However, its immunomodulatory effects on host cells are poorly understood.MethodsHere, we cloned the HCA59 gene and expressed the recombinant protein of HCA59 (rHCA59). Binding activities of rHCA59 to goat peripheral blood mononuclear cells (PBMCs) and dendritic cells (DCs) were checked by immunofluorescence assay (IFA) and the immunoregulatory effects of rHCA59 on cytokine secretions, cell migration, cell proliferation, nitric oxide production, and changes in expression of genes in related pathways were observed by co-incubation of rHCA59 with goat PBMCs and DCs. Monocyte phagocytosis and characterization of goat blood DC subsets were detected by flow cytometry.ResultsThe IFA results revealed that rHCA59 could bind to PBMCs and DCs. Treatment of PBMCs with rHCA59 significantly increased cellular proliferation and NO production in a dose–dependent manner, while cell migration was vigorously blocked. Treatment with rHCA59 significantly suppressed monocytes phagocytosis. The quantity of surface marker CD80 on DCs increased significantly after rHCA59 treatment. In addition, the expression of genes included in the WNT pathway was related to the differentiation and maturation of DCs, and the production of IL-10 and IL-17 produced by PBMCs was altered.ConclusionsOur findings illustrated that rHCA59 could enhance host immune responses by regulating the functions of goat PBMCs and DCs, which would benefit our understanding of HCA59 from parasitic nematodes contributing to the mechanism of parasitic immune evasion.

HIV Replication in Humanized IL-3/GM-CSF-Transgenic NOG Mice.

The development of mouse models that mimic the kinetics of Human Immunodeficiency Virus (HIV) infection is critical for the understanding of the pathogenesis of disease and for the design of novel therapeutic strategies. Here, we describe the dynamics of HIV infection in humanized NOD/Shi-scid-IL2rγnull (NOG) mice bearing the human genes for interleukin (IL)-3 and granulocyte-macrophage colony-stimulating factor (GM-CSF) (NOG-EXL mice). The kinetics of viral load, as well as the frequencies of T-cells, B-cells, Natural killer cells (NK), monocytes, and dendritic cells in blood and secondary lymphoid organs were evaluated throughout the time of infection. In comparison with a non-transgenic humanized mouse (NSG) strain, lymphoid and myeloid populations were more efficiently engrafted in humanized NOG-EXL mice, both in peripheral blood and lymphoid tissues. In addition, HIV actively replicated in humanized NOG-EXL mice, and infection induced a decrease in the percentage of CD4+ T-cells, inversion of the CD4:CD8 ratio, and changes in some cell populations, such as monocytes and dendritic cells, that recapitulated those found in human natural infection. Thus, the humanized IL-3/GM-CSF-transgenic NOG mouse model is suitable for the study of the dynamics of HIV infection and provides a tool for basic and preclinical studies.

The role of dendritic cells regulated by HMGB1/TLR4 signalling pathway in myocardial ischaemia reperfusion injury.

Inflammatory response plays an important role in ischaemia reperfusion injury (IRI) through a variety of inflammatory cells. Apart from neutrophils, macrophages and lymphocytes, the role of dendritic cells (DCs) in IRI has been noticed. The study was aimed at investigating whether the high‐mobility group protein box‐1/toll like receptor 4 (HMGB1/TLR4) signalling pathway regulate the migration, adhesion and aggregation of DCs to the myocardium, induce DCs activation and maturation, stimulate the expression of surface costimulatory molecules and participate in myocardial IRI. In vivo, migration, adhesion, and aggregation of DCs was enhanced; the expression of peripheral blood DCs CD80 and CD86, myocardial adhesion molecules were increased; and the infarct size was increased during myocardial ischaemia reperfusion injury myocardial ischemic/reperfusion injury (MI/RI). These responses induced by MI/RI were significantly inhibited by HMGB1 specific neutralizing antibody treatment. Cellular experiments confirmed that HMGB1 promoted the release of inflammatory cytokines through TLR4/MyD88/NF‐κB, upregulated CD80 and CD86 expression, mediated the damage of cardiomyocytes and accelerated the apoptosis. Our results indicate that DCs activation and maturation, stimulate the expression of surface costimulatory molecules by promoting the release of inflammatory factors through NF‐κB pathway and participate in myocardial IRI.

A promising approach to targeting type 1 IFN in systemic lupus erythematosus.

Despite advances in understanding systemic lupus erythematosus (SLE) pathogenesis, most clinical trials of new targeted therapies have been met with disappointment. The type I IFN pathway is believed to play an important role in SLE, and the proposed involvement of this pathway helps explain the frustration behind the failure at targeting either IFN-α or the type 1 IFN receptor itself. In this issue of the JCI, Furie et al. report on an intriguing phase 1b study that demonstrates an approach for inhibiting this pathway in the skin using an mAB (BIIB059) that targets the blood DC antigen 2 (BDCA-2) receptor on plasmacytoid DCs (pDCs). BIIB059 decreased IFN expression and improved cutaneous lupus disease activity, with a favorable safety profile. Whether or not this strategy will be effective in managing SLE in other organs remains unanswered. However, these results suggest that closing the door on targeting the type 1 IFN pathway in SLE may be premature and highlight the emerging question of whether an organ-specific approach toward lupus trials and treatment should be the wave of the future.

Study inhibition and apoptosis of peripheral blood dendritic cells hybridize tumor vaccine induced systematic immune effector cells to the BxPC-3 in vitro

Objective To observe the inhibition and apoptosis effects of systematic immune effector cells (SIECs) induced by increased expansion of normal human peripheral venous blood dendritic cells (DCs) hybridoma vaccine on orthotopic pancreatic cancer cell line (BxPC-3) in vitro. Methods The peripheral blood mononuclear cells (PBMCs) of healthy human were obtained by gradient centrifugation of lymphocyte separation fluid, and DCs and DCs derived monocytes cells (SIECs) were obtained by adherent method. DCs and SIECs were respectively cultured with granulocyte macrophage-colony stimulating factor (GM-CSF), interleukin (IL)-4, tumor necrosis factor-α (TNF-α), IL-2, BxPC-3 tumor specific antigen (pc-3tsa). After five days, DCs were collected and counted. BxPC-3TAA-sensitized DCs (referred to as sensitive DCs), and DCs were fused with BxPC-3 by PEG+ 10% dimethylsurfoxide (DMSO) with 10∶1, 5∶1, 1∶5 to obtain sensitive DCs-BxPC-3 and DCs-BxPC-3 fusion tumor vaccines. On the 7th day, SIECs were respectively mixed with sensitive DCs-BxPC-3, DCs-BxPC-3, sensitive DCs, and DCs for 1 days in a 40∶1 mixture. The mixed cultured cells were collected, and the Annexin V-fluoresceine isothiocyanate (FITC)/propidium iodide (PI) apoptosis assay and cell counting kit-8 (CCK-8) toxicity assay were performed on BxPC-3 in the mixed target SIECs∶BxPC3=10∶1. Results The sensitives DCs, DCs and BxPC-3 were fused, and the fusion effect was the best when the ratio was 1∶1, and the fusion rate was 40.0%. The CCK-8 assay showed that the inhibition rates of BxPC-3 induced by SIECs and SIECs by sensitive DCs-BxPC-3, DCs-BxPC-3, sensitive DCs and DCs were 53.1%, 45.3% and 78.8%, respectively. The Annexin V-FITC/PI assay showed that apoptosis rates of sensitive DCs-BxPC-3, DCs-BxPC-3, sensitive DCs, DCs and SIECs were 24.17%, 11.43%, 85.87% and 29.94%. Conclusion Tumor antigen sequential sensitization DCs have a superimposed effect on antigen acquisition, which can play a better anti-tumor effect. Early DCs fusion tumor vaccine can induce SIECs to inhibit tumor cells to a certain extent. Key words: Dendritic cells; Sequential sensitization; Pancreatic cancer; Tumor vaccine; Cell inhibition; Apoptosis

Circulating and Hepatic BDCA1+, BDCA2+, and BDCA3+ Dendritic Cells Are Differentially Subverted in Patients With Chronic HBV Infection.

Background and aims: Chronic hepatitis B virus (HBV) infection is a major health burden potentially evolving toward cirrhosis and hepatocellular carcinoma. HBV physiopathology is strongly related to the host immunity, yet the mechanisms of viral evasion from immune-surveillance are still misunderstood. The immune response elicited at early stages of viral infection is believed to be important for subsequent disease outcome. Dendritic cells (DCs) are crucial immune sentinels which orchestrate antiviral immunity, which offer opportunity to pathogens to subvert them to escape immunity. Despite the pivotal role of DCs in orientating antiviral responses and determining the outcome of infection, their precise involvement in HBV pathogenesis is not fully explored.Methods: One hundred thirty chronically HBV infected patients and 85 healthy donors were enrolled in the study for blood collection, together with 29 chronically HBV infected patients and 33 non-viral infected patients that were included for liver biopsy collection. In a pioneer way, we investigated the phenotypic and functional features of both circulating and intrahepatic BDCA1+ cDC2, BDCA2+ pDCs, and BDCA3+ cDC1 simultaneously in patients with chronic HBV infection by designing a unique multi-parametric flow cytometry approach.Results: We showed modulations of the frequencies and basal activation status of blood and liver DCs associated with impaired expressions of specific immune checkpoints and TLR molecules on circulating DC subsets. Furthermore, we highlighted an impaired maturation of circulating and hepatic pDCs and cDCs following stimulation with specific TLR agonists in chronic HBV patients, associated with drastic dysfunctions in the capacity of circulating DC subsets to produce IL-12p70, TNFα, IFNα, IFNλ1, and IFNλ2 while intrahepatic DCs remained fully functional. Most of these modulations correlated with HBsAg and HBV DNA levels.Conclusion: We highlight potent alterations in the distribution, phenotype and function of all DC subsets in blood together with modulations of intrahepatic DCs, revealing that HBV may hijack the immune system by subverting DCs. Our findings provide innovative insights into the immuno-pathogenesis of HBV and the mechanisms of virus escape from immune control. Such understanding is promising for developing new therapeutic strategies restoring an efficient immune control of the virus.

Dendritic Cell Regulation of Graft-Vs.-Host Disease: Immunostimulation and Tolerance.

Graft-vs.-host disease (GVHD) remains a significant cause of morbidity and mortality after allogeneic hematopoietic stem cell transplantation (allo-HSCT). Significant progresses have been made in defining the dichotomous role of dendritic cells (DCs) in the development of GVHD. Host-derived DCs are important to elicit allogeneic T cell responses, whereas certain donor-types of DCs derived from newly engrafted hematopoietic stem/progenitor cells (HSPCs) can amply this graft-vs.-host reaction. In contrast, some DCs also play non-redundant roles in mediating immune tolerance. They induce apoptotic deletion of host-reactive donor T cells while promoting expansion and function of regulatory T cells (Treg). Unfortunately, this tolerogenic effect of DCs is impaired during GVHD. Severe GVHD in patients subject to allo-HSCT is associated with significantly decreased number of circulating peripheral blood DCs during engraftment. Existing studies reveal that GVHD causes delayed reconstitution of donor DCs from engrafted HSPCs, impairs the antigen presentation function of newly generated DCs and reduces the capacity of DCs to regulate Treg. The present review will discuss the importance of DCs in alloimmunity and the mechanism underlying DC reconstitution after allo-HSCT.

Activation of Human Dendritic Cells by Ascophyllan Purified from Ascophyllum nodosum.

In our previous study, we showed that ascophyllan purified from Ascophyllum nodosum treatment promotes mouse dendritic cell (DC) activation in vivo, further induces an antigen-specific immune response and has anticancer effects in mice. However, the effect of ascophyllan has not been studied in human immune cells, specifically in terms of activation of human monocyte-derived DCs (MDDCs) and human peripheral blood DCs (PBDCs). We found that the treatment with ascophyllan induced morphological changes in MDDCs and upregulated co-stimulatory molecules and major histocompatibility complex class I (MHC I) and MHC II expression. In addition, pro-inflammatory cytokine levels in culture medium was also dramatically increased following ascophyllan treatment of MDDCs. Moreover, ascophyllan promoted phosphorylation of ERK, p38 and JNK signaling pathways, and inhibition of p38 almost completely suppressed the ascophyllan-induced activation of MDDCs. Finally, treatment with ascophyllan induced activation of BDCA1 and BDCA3 PBDCs. Thus, these data suggest that ascophyllan could be used as an immune stimulator in humans.

The effect of everolimus and low-dose cyclophosphamide on immune cell subsets in patients with metastatic renal cell carcinoma: results from a phase I clinical trial

For the treatment of metastatic renal cell cancer several strategies are used among which the mTOR inhibitor everolimus. As mTOR plays an important role in the immune system, e.g., by controlling the expression of the transcription factor FoxP3 thereby regulating regulatory T cells (Tregs), it plays a key role in the balance between tolerance and inflammation. Previous reports showed stimulatory effects of mTOR inhibition on the expansion of Tregs, an effect that can be considered detrimental in terms of cancer control. Since metronomic cyclophosphamide (CTX) was shown to selectively deplete Tregs, a phase 1 clinical trial was conducted to comprehensively investigate the immune-modulating effects of several dosages and schedules of CTX in combination with the standard dose of everolimus, with the explicit aim to achieve selective Treg depletion. Our data show that 50 mg of CTX once daily and continuously administered, in combination with the standard dose of 10 mg everolimus once daily, not only results in depletion of Tregs, but also leads to a reduction in MDSC, a sustained level of the CD8+ T-cell population accompanied by an increased effector to suppressor ratio, and reversal of negative effects on three peripheral blood DC subsets. These positive effects on the immune response may contribute to improved survival, and therefore this combination therapy is further evaluated in a phase II clinical trial.

In vitro characteristics of peripheral blood dendritic cells in patients with pancreatic cancer

In vitro characteristics of peripheral blood dendritic cells in patients with pancreatic cancer