Altered expression and endocytic function of CD205 in human dendritic cells, and detection of a CD205-DCL-1 fusion protein upon dendritic cell maturation

An approach for developing a blood-based screening panel for lung cancer based on clonal hematopoietic mutations

Early detection can significantly reduce mortality due to lung cancer. Presented here is an approach for developing a blood-based screening panel based on clonal hematopoietic mutations. Animal model studies suggest that clonal hematopoietic mutations in tumor infiltrating immune cells can modulate cancer progression, representing potential predictive biomarkers. The goal of this study was to determine if the clonal expansion of these mutations in blood samples could predict the occurrence of lung cancer. A set of 98 potentially pathogenic clonal hematopoietic mutations in tumor infiltrating immune cells were identified using sequencing data from lung cancer samples. These mutations were used as predictors to develop a logistic regression machine learning model. The model was tested on sequencing data from a separate set of 578 lung cancer and 545 non-cancer samples from 18 different cohorts. The logistic regression model correctly classified lung cancer and non-cancer blood samples with 94.12% sensitivity (95% Confidence Interval: 92.20-96.04%) and 85.96% specificity (95% Confidence Interval: 82.98-88.95%). Our results suggest that it may be possible to develop an accurate blood-based lung cancer screening panel using this approach. Unlike most other "liquid biopsies" currently under development, the approach presented here is based on standard sequencing protocols and uses a relatively small number of rationally selected mutations as predictors.

Components, Formulations, Deliveries, and Combinations of Tumor Vaccines

Tumor vaccines, an important part of immunotherapy, prevent cancer or kill existing tumor cells by activating or restoring the body's own immune system. Currently, various formulations of tumor vaccines have been developed, including cell vaccines, tumor cell membrane vaccines, tumor DNA vaccines, tumor mRNA vaccines, tumor polypeptide vaccines, virus-vectored tumor vaccines, and tumor-in-situ vaccines. There are also multiple delivery systems for tumor vaccines, such as liposomes, cell membrane vesicles, viruses, exosomes, and emulsions. In addition, to decrease the risk of tumor immune escape and immune tolerance that may exist with a single tumor vaccine, combination therapy of tumor vaccines with radiotherapy, chemotherapy, immune checkpoint inhibitors, cytokines, CAR-T therapy, or photoimmunotherapy is an effective strategy. Given the critical role of tumor vaccines in immunotherapy, here, we look back to the history of tumor vaccines, and we discuss the antigens, adjuvants, formulations, delivery systems, mechanisms, combination therapy, and future directions of tumor vaccines.

Modulation of Dendritic Cell Function via Nanoparticle-Induced Cytosolic Calcium Changes

Calcium nanoparticles have been investigated for applications, such as drug and gene delivery. Additionally, Ca2+ serves as a crucial second messenger in the activation of immune cells. However, few studies have systematically studied the effects of calcium nanoparticles on the calcium levels and functions within immune cells. In this study, we explore the potential of calcium nanoparticles as a vehicle to deliver calcium into the cytosol of dendritic cells (DCs) and influence their functions. We synthesized calcium hydroxide nanoparticles, coated them with a layer of silica to prevent rapid degradation, and further conjugated them with anti-CD205 antibodies to achieve targeted delivery to DCs. Our results indicate that these nanoparticles can efficiently enter DCs and release calcium ions in a controlled manner. This elevation in cytosolic calcium activates both the NFAT and NF-κB pathways, in turn promoting the expression of costimulatory molecules, antigen-presenting molecules, and pro-inflammatory cytokines. In mouse tumor models, the calcium nanoparticles enhanced the antitumor immune response and augmented the efficacy of both radiotherapy and chemotherapy without introducing additional toxicity. Our study introduces a safe nanoparticle immunomodulator with potential widespread applications in cancer therapy.

The adaptive evolution of cancer driver genes

BACKGROUND

Cancer is a life-threatening disease in humans; yet, cancer genes are frequently reported to be under positive selection. This suggests an evolutionary-genetic paradox in which cancer evolves as a secondary product of selection in human beings. However, systematic investigation of the evolution of cancer driver genes is sparse.

RESULTS

Using comparative genomics analysis, population genetics analysis and computational molecular evolutionary analysis, the evolution of 568 cancer driver genes of 66 cancer types were evaluated at two levels, selection on the early evolution of humans (long timescale selection in the human lineage during primate evolution, i.e., millions of years), and recent selection in modern human populations (~ 100,000 years). Results showed that eight cancer genes covering 11 cancer types were under positive selection in the human lineage (long timescale selection). And 35 cancer genes covering 47 cancer types were under positive selection in modern human populations (recent selection). Moreover, SNPs associated with thyroid cancer in three thyroid cancer driver genes (CUX1, HERC2 and RGPD3) were under positive selection in East Asian and European populations, consistent with the high incidence of thyroid cancer in these populations.

CONCLUSIONS

These findings suggest that cancer can be evolved, in part, as a by-product of adaptive changes in humans. Different SNPs at the same locus can be under different selection pressures in different populations, and thus should be under consideration during precision medicine, especially for targeted medicine in specific populations.

Regulation of biomaterial implantation-induced fibrin deposition to immunological functions of dendritic cells

The performance of implanted biomaterials is largely determined by their interaction with the host immune system. As a fibrous-like 3D network, fibrin matrix formed at the interfaces of tissue and material, whose effects on dendritic cells (DCs) remain unknown. Here, a bone plates implantation model was developed to evaluate the fibrin matrix deposition and DCs recruitment in vivo. The DCs responses to fibrin matrix were further analyzed by a 2D and 3D fibrin matrix model in vitro. In vivo results indicated that large amount of fibrin matrix deposited on the interface between the tissue and bone plates, where DCs were recruited. Subsequent in vitro testing denoted that DCs underwent significant shape deformation and cytoskeleton reorganization, as well as mechanical property alteration. Furthermore, the immune function of imDCs and mDCs were negatively and positively regulated, respectively. The underlying mechano-immunology coupling mechanisms involved RhoA and CDC42 signaling pathways. These results suggested that fibrin plays a key role in regulating DCs immunological behaviors, providing a valuable immunomodulatory strategy for tissue healing, regeneration and implantation.

Regulation of biomaterial implantation-induced fibrin deposition to immunological functions of dendritic cells

The performance of implanted biomaterials is largely determined by their interaction with the host immune system. As a fibrous-like 3D network, fibrin matrix formed at the interfaces of tissue and material, whose effects on dendritic cells (DCs) remain unknown. Here, a bone plates implantation model was developed to evaluate the fibrin matrix deposition and DCs recruitment in vivo. The DCs responses to fibrin matrix were further analyzed by a 2D and 3D fibrin matrix model in vitro. In vivo results indicated that large amount of fibrin matrix deposited on the interface between the tissue and bone plates, where DCs were recruited. Subsequent in vitro testing denoted that DCs underwent significant shape deformation and cytoskeleton reorganization, as well as mechanical property alteration. Furthermore, the immune function of imDCs and mDCs were negatively and positively regulated, respectively. The underlying mechano-immunology coupling mechanisms involved RhoA and CDC42 signaling pathways. These results suggested that fibrin plays a key role in regulating DCs immunological behaviors, providing a valuable immunomodulatory strategy for tissue healing, regeneration and implantation.

Irg1/itaconate metabolic pathway is a crucial determinant of dendritic cells immune-priming function and contributes to resolute allergen-induced airway inflammation

Itaconate is produced from the mitochondrial TCA cycle enzyme aconitase decarboxylase (encoded by immune responsive gene1; Irg1) that exerts immunomodulatory function in myeloid cells. However, the role of the Irg1/itaconate pathway in dendritic cells (DC)-mediated airway inflammation and adaptive immunity to inhaled allergens, which are the primary antigen-presenting cells in allergic asthma, remains largely unknown. House dust mite (HDM)-challenged Irg1^-/- mice displayed increases in eosinophilic airway inflammation, mucous cell metaplasia, and Th2 cytokine production with a mechanism involving impaired mite antigen presentations by DC. Adoptive transfer of HDM-pulsed DC from Irg1-deficient mice into naïve WT mice induced a similar phenotype of elevated type 2 airway inflammation and allergic sensitization. Untargeted metabolite analysis of HDM-pulsed DC revealed itaconate as one of the most abundant polar metabolites that potentially suppress mitochondrial oxidative damage. Furthermore, the immunomodulatory effect of itaconate was translated in vivo, where intranasal administration of 4-octyl itaconate 4-OI following antigen priming attenuated the manifestations of HDM-induced airway disease and Th2 immune response. Taken together, these data demonstrated for the first time a direct regulatory role of the Irg1/itaconate pathway in DC for the development of type 2 airway inflammation and suggest a possible therapeutic target in modulating allergic asthma.

Distinct immune signatures discriminate between asymptomatic and presymptomatic SARS-CoV-2pos subjects

Increasing numbers of SARS-CoV-2-positive (SARS-CoV-2^pos) subjects are detected at silent SARS-CoV-2 infection stage (SSIS). Yet, SSIS represents a poorly examined time-window wherein unknown immunity patterns may contribute to the fate determination towards persistently asymptomatic or overt disease. Here, we retrieved blood samples from 19 asymptomatic and 12 presymptomatic SARS-CoV-2^pos subjects, 47 age/gender-matched patients with mild or moderate COVID-19 and 27 normal subjects, and interrogated them with combined assays of 44-plex CyTOF, RNA-seq and Olink. Notably, both asymptomatic and presymptomatic subjects exhibited numerous readily detectable immunological alterations, while certain parameters including more severely decreased frequencies of CD107a^low classical monocytes, intermediate monocytes, non-classical monocytes and CD62L^hi CD8⁺ T_naïve cells, reduced plasma STC1 level but an increased frequency of CD4⁺ NKT cells combined to distinguish the latter. Intercorrelation analyses revealed a particular presymptomatic immunotype mainly manifesting as monocytic overactivation and differentiation blockage, a likely lymphocyte exhaustion and immunosuppression, yielding mechanistic insights into SSIS fate determination, which could potentially improve SARS-CoV-2 management.

Targeting CD205 with the antibody drug conjugate MEN1309/OBT076 is an active new therapeutic strategy in lymphoma models

Antibody drug conjugates represent an important class of anti-cancer drugs in both solid tumors and hematological cancers. Here, we report preclinical data on the anti-tumor activity of the first-in-class antibody drug conjugate MEN1309/OBT076 targeting CD205. The study included preclinical in vitro activity screening on a large panel of cell lines, both as single agent and in combination and validation experiments on in vivo models. CD205 was first shown frequently expressed in lymphomas, leukemias and multiple myeloma by immunohistochemistry on tissue microarrays. Anti-tumor activity of MEN1309/OBT076 as single agent was then shown across 42 B-cell lymphoma cell lines with a median IC50 of 200 pM and induction of apoptosis in 25/42 (59.5%) of the cases. The activity appeared highly correlated with its target expression. After in vivo validation as the single agent, the antibody drug conjugate synergized with the BCL2 inhibitor venetoclax, and the anti-CD20 monoclonal antibody rituximab. The first-in-class antibody drug targeting CD205, MEN1309/OBT076, demonstrated strong pre-clinical anti-tumor activity in lymphoma, warranting further investigations as a single agent and in combination.

Generating Bovine Monocyte-Derived Dendritic Cells for Experimental and Clinical Applications Using Commercially Available Serum-Free Medium

Advances in fundamental and applied immunology research often originate from pilot studies utilizing animal models. While cattle represent an ideal model for disease pathogenesis and vaccinology research for a number of human disease, optimized bovine culture models have yet to be fully established. Monocyte-derived dendritic cells (MoDC) are critical in activating adaptive immunity and are an attractive subset for experimental and clinical applications. The use of serum-supplemented culture medium in this ex vivo approach is undesirable as serum contains unknown quantities of immune-modulating components and may induce unwanted immune responses if not autologous. Here, we describe a standardized protocol for generating bovine MoDC in serum-free medium (AIM-V) and detail the MoDC phenotype, cytokine profile, and metabolic signature achieved using this culture methodology. MoDC generated from adult, barren cattle were used for a series of experiments that evaluated the following culture conditions: medium type, method of monocyte enrichment, culture duration, and concentration of differentiation additives. Viability and yield were assessed using flow cytometric propidium iodide staining and manual hemocytometer counting, respectively. MoDC phenotype and T cell activation and proliferation were assessed by flow cytometric analysis of surface markers (MHC class II, CD86, CD14, and CD205), and CD25 and CFSE respectively. Cytokine secretion was quantified using a multiplex bovine cytokine panel (IL-1α, IL-1β, IL-8, IL-10, IL-17A, IFN-γ, MIP-1α, TNF-α, and IL-4). Changes in cell metabolism following stimulation were analyzed using an Extracellular Flux (XFe96) Seahorse Analyzer. Data were analyzed using paired t-tests and repeated measures ANOVA. Immature MoDC generated in serum-free medium using magnetic-activated cell sorting with plate adhesion to enrich monocytes and cultured for 4 days have the following phenotypic profile: MHC class II⁺⁺⁺, CD86⁺, CD205⁺⁺, and CD14^-. These MoDC can be matured with PMA and ionomycin as noted by increased CD86 and CD40 expression, increased cytokine secretion (IL-1α, IL-10, MIP-1α, and IL-17A), a metabolic switch to aerobic glycolysis, and induction of T cell activation and proliferation following maturation. Cultivation of bovine MoDC utilizing our well-defined culture protocol offers a serum-free approach to mechanistically investigate mechanisms of diseases and the safety and efficacy of novel therapeutics for both humans and cattle alike.

Nanovaccine impact on dendritic cells: transcriptome analysis enables new insights into antigen and adjuvant effects

Aim: For vaccines the combination between an antigen and adjuvants are both crucially important to trigger an effective immune response in dendritic cells. Innovative adjuvants like resiquimod or muramyldipeptide have their target protein inside the cell. Materials & methods: Up/downregulation and proteome expression was investigated for the adjuvant combination resiquimod and muramyldipeptide in a soluble form versus encapsulated into a nanocarrier. Results: We found that 1225 genes were upregulated after nanocarrier treatment while 478 genes were downregulated. Most prominent were interferon-stimulated genes with more than 25-times higher expression after nanocarrier treatment, for example RSAD2 and ISG15, which were recently found to have antiviral or antitumor effects. Conclusion: Encapsulation gives a more effective upregulation of vaccine-related genes.

Theileria annulata transformation altered cell surface molecules expression and endocytic function of monocyte-derived dendritic cells

Theileria annulata is a protozoan parasite transmitted by ticks to cattle. The most important processes of T. annulata are the infection and transformation of host monocytes, which promote cell division and generate a neoplastic phenotype. Dendritic cells play an important role in the development of adaptive immune responses against parasites and are traditionally classified into four types. One type of dendritic cell derived from afferent lymph was successfully transformed by T. annulata in vitro in a previous report. However, whether the monocyte-derived dendritic cells could be transformed and how the endocytic function is affected by T. annulata infection were not yet known. Bovine dendritic cells (DCs) derived from blood CD14⁺ monocytes were cocultured with T. annulata sporozoites in vitro. On day 15 post infection, rounded and continuously proliferating cells were observed. The effect of this transformation on cell phenotype was studied using immunostaining and flow cytometry. After transformation, the cells maintained the expression of the DC-specific marker CD11c, but it was downregulated as were the expression of CD11b, CD14 and CD86. In contrast, CD205, CD45 and MHC class Ⅱ molecules were upregulated in transformed cells. The levels of CD172a, CD21, CD40 and CD80 expression were very low in the transformed cells (<1 %). However, the transformed cells maintained high expression levels of MHC Ⅰ (>99 %). In addition, the normal and transformed DCs were cocultured with OVA-FITC antigen to compare the differences of the endocytic functions between these two types of cells. The results revealed that the endocytic functions of MoDCs were significantly inhibited after transformation by T. annulata.

Stories From the Dendritic Cell Guardhouse

Phagocytic cells [dendritic cells (DCs), macrophages, monocytes, neutrophils, and mast cells] utilize C-type (Ca²⁺-dependent) lectin-like (CLEC) receptors to identify and internalize pathogens or danger signals. As monitors of environmental imbalances, CLEC receptors are particularly important in the function of DCs. Activation of the immune system requires, in sequence, presentation of antigen to the T cell receptor (TCR) by DCs, interaction of co-stimulatory factors such as CD40/80/86 on DCs with CD40L and CD28 on T cells, and production of IL-12 and/or IFN-α/β to amplify T cell differentiation and expansion. Without this sequence of events within an inflammatory environment, or in a different order, antigen-specific T cells become unresponsive, are deleted or become regulatory T cells. Thus, the mode by which CLEC receptors on DCs are engaged can either elicit activation of T cells to achieve an immune response or induce tolerance. This minireview illustrates these aspects with Dectin-1, DEC205, the mannose receptor and CLEC10A as examples.

MEN1309/OBT076, a First-In-Class Antibody-Drug Conjugate Targeting CD205 in Solid Tumors

CD205 is a type I transmembrane glycoprotein and is a member of the C-type lectin receptor family. Analysis by mass spectrometry revealed that CD205 was robustly expressed and highly prevalent in a variety of solid malignancies from different histotypes. IHC confirmed the increased expression of CD205 in pancreatic, bladder, and triple-negative breast cancer (TNBC) compared with that in the corresponding normal tissues. Using immunofluorescence microscopy, rapid internalization of the CD205 antigen was observed. These results supported the development of MEN1309/OBT076, a fully humanized CD205-targeting mAb conjugated to DM4, a potent maytansinoid derivate, via a cleavable N-succinimidyl-4-(2-pyridyldithio) butanoate linker. MEN1309/OBT076 was characterized in vitro for target binding affinity, mechanism of action, and cytotoxic activity against a panel of cancer cell lines. MEN1309/OBT076 displayed selective and potent cytotoxic effects against tumor cells exhibiting strong and low to moderate CD205 expression. In vivo, MEN1309/OBT076 showed potent antitumor activity resulting in durable responses and complete tumor regressions in many TNBC, pancreatic, and bladder cancer cell line-derived and patient-derived xenograft models, independent of antigen expression levels. Finally, the pharmacokinetics and pharmacodynamic profile of MEN1309/OBT076 was characterized in pancreatic tumor-bearing mice, demonstrating that the serum level of antibody-drug conjugate (ADC) achieved through dosing was consistent with the kinetics of its antitumor activity. Overall, our data demonstrate that MEN1309/OBT076 is a novel and selective ADC with potent activity against CD205-positive tumors. These data supported the clinical development of MEN1309/OBT076, and further evaluation of this ADC is currently ongoing in the first-in-human SHUTTLE clinical trial.

Acute aerobic exercise induces a preferential mobilisation of plasmacytoid dendritic cells into the peripheral blood in man

Dendritic cells (DCs) are important sentinel cells of the immune system responsible for presenting antigen to T cells. Exercise is known to cause an acute and transient increase in the frequency of DCs in the bloodstream in humans, yet there are contradictory findings in the literature regarding the phenotypic composition of DCs mobilised during exercise, which may have implications for immune regulation and health. Accordingly, we sought to investigate the composition of DC sub-populations mobilised in response to acute aerobic exercise. Nine healthy males (age, 21.9 ± 3.6 years; height, 177.8 ± 5.4 cm; body mass, 78.9 ± 10.8 kg; body mass index, 24.9 ± 3.3 kg·m²; V̇O_{2 MAX}, 41.5 ± 5.1 mL·kg·min^-1) cycled for 20 min at 80% V̇O_{2 MAX}. Blood was sampled at baseline, during the final minute of exercise and 30 min later. Using flow cytometry, total DCs were defined as Lineage- (CD3, CD19, CD20, CD14, CD56) HLA-DR+ and subsequently identified as plasmacytoid DCs (CD303+) and myeloid DCs (CD303-). Myeloid DCs were analysed for expression of CD1c and CD141 to yield four sub-populations; CD1c-CD141+; CD1c+CD141+; CD1c+CD141- and CD1c-CD141-. Expression of CD205 was also analysed on all DC sub-populations to identify DCs capable of recognising apoptotic and necrotic cells. Total DCs increased by 150% during exercise (F_(1,10) = 60; p < 0.05, η² = 0.9). Plasmacytoid DCs mobilised to a greater magnitude than myeloid DCs (195 ± 131% vs. 131 ± 100%; p < 0.05). Among myeloid DCs, CD1c-CD141- cells showed the largest exercise-induced mobilisation (167 ± 122%), with a stepwise pattern observed among the remaining sub-populations: CD1c+CD141- (79 ± 50%), followed by CD1c+CD141+ (44 ± 41%), with the smallest response shown by CD1c-CD141+ cells (23 ± 54%) (p < 0.05). Among myeloid DCs, CD205- cells were the most exercise responsive. All DC subsets returned to resting levels within 30 min of exercise cessation. These results show that there is a preferential mobilisation of plasmacytoid DCs during exercise. Given the functional repertoire of plasmacytoid DCs, which includes the production of interferons against viral and bacterial pathogens, these findings indicate that exercise may augment immune-surveillance by preferentially mobilising effector cells; these findings have general implications for the promotion of exercise for health, and specifically for the optimisation of DC harvest for cancer immunotherapy.

Expression, Distribution, and Role of C-Type Lectin Receptors in the Human and Animal Middle Ear and Eustachian Tube: A Review

Otitis media (OM) is a group of inflammatory diseases of the middle ear (ME), regardless of cause or pathological mechanism. Among the molecular biological studies assessing the pathology of OM are investigations into the expression of C-type lectin receptors (CLR) in the ME and Eustachian tube (ET). To date, nine studies have evaluated CLR expression in the ME and ET. The expression of individual CLRs in mammalian ME and ET varies by species and model of OM. Assessments have shown that the patterns of CLR expression in the ME and ET vary; that CLR expression may vary by type of OM; and that the distribution and levels of expression of CLRs may depend on the presence or absence of inflammation, with variations even within the same species and same tissue. Infection of the ME and ET with various pathogens is a common cause of all types of OM, with host responses to pathogens mediated initially by the innate immune system. CLRs are important factors in the innate immune system because they act as both adhesion molecules and as pathogen recognition receptors. The expression of CLRs in OM tissues suggests that CLRs are associated with the pathogenesis of various types of OM.

The mannose receptor LY75 (DEC205/CD205) modulates cellular phenotype and metastatic potential of ovarian cancer cells

The molecular basis of epithelial ovarian cancer (EOC) dissemination is still poorly understood. Previously, we identified the mannose receptor LY75 gene as hypomethylated in high-grade (HG) serous EOC tumors, compared to normal ovarian tissues. LY75 represents endocytic receptor expressed on dendritic cells and so far, has been primarily studied for its role in antigen processing and presentation. Here we demonstrate that LY75 is overexpressed in advanced EOC and that LY75 suppression induces mesenchymal-to-epithelial transition (MET) in EOC cell lines with mesenchymal morphology (SKOV3 and TOV112), accompanied by reduction of their migratory and invasive capacity in vitro and enhanced tumor cell colonization and metastatic growth in vivo. LY75 knockdown in SKOV3 cells also resulted in predominant upregulation of functional pathways implicated in cell proliferation and metabolism, while pathways associated with cell signaling and adhesion, complement activation and immune response were mostly suppressed. Moreover, LY75 suppression had an opposite effect on EOC cell lines with epithelial phenotype (A2780s and OV2008), by directing epithelial-to-mesenchymal transition (EMT) associated with reduced capacity for in vivo EOC cell colonization, as similar/identical signaling pathways were reversely regulated, when compared to mesenchymal LY75 knockdown EOC cells.To our knowledge, this is the first report of a gene displaying such pleiotropic effects in sustaining the cellular phenotype of EOC cells and points to novel functions of this receptor in modulating EOC dissemination. Our data also support previous findings regarding the superior capacity of epithelial cancer cells in metastatic colonization of distant sites, compared to cancer cells with mesenchymal-like morphology.

CpG Oligodeoxinucleotides and Flagellin Modulate the Immune Response to Antigens Targeted to CD8α+ and CD8α- Conventional Dendritic Cell Subsets

Dendritic cells (DCs) are antigen-presenting cells essential for the induction of adaptive immune responses. Their unprecedented ability to present antigens to T cells has made them excellent targets for vaccine development. In the last years, a new technology based on antigen delivery directly to different DC subsets through the use of hybrid monoclonal antibodies (mAbs) to DC surface receptors fused to antigens of interest opened new perspectives for the induction of robust immune responses. Normally, the hybrid mAbs are administered with adjuvants that induce DC maturation. In this work, we targeted an antigen to the CD8α⁺ or the CD8α⁻ DC subsets in the presence of CpG oligodeoxinucleotides (ODN) or bacterial flagellin, using hybrid αDEC205 or αDCIR2 mAbs, respectively. We also accessed the role of toll-like receptors (TLRs) 5 and 9 signaling in the induction of specific humoral and cellular immune responses. Wild-type and TLR5 or TLR9 knockout mice were immunized with two doses of the hybrid αDEC205 or αDCIR2 mAbs, as well as with an isotype control, together with CpG ODN 1826 or flagellin. A chimeric antigen containing the Plasmodium vivax 19 kDa portion of the merozoite surface protein (MSP1₁₉) linked to the Pan-allelic DR epitope was fused to each mAb. Specific CD4⁺ T cell proliferation, cytokine, and antibody production were analyzed. We found that CpG ODN 1826 or flagellin were able to induce CD4⁺ T cell proliferation, CD4⁺ T cells producing pro-inflammatory cytokines, and specific antibodies when the antigen was targeted to the CD8α⁺ DC subset. On the other hand, antigen targeting to CD8α⁻ DC subset promoted specific antibody responses and proliferation, but no detectable pro-inflammatory CD4⁺ T cell responses. Also, specific antibody responses after antigen targeting to CD8α⁺ or CD8α⁻ DCs were reduced in the absence of TLR9 or TLR5 signaling, while CD4⁺ T cell proliferation was mainly affected after antigen targeting to CD8α⁺ DCs and in the absence of TLR9 signaling. These results extend our understanding of the modulation of specific immune responses induced by antigen targeting to DCs in the presence of different adjuvants. Such knowledge may be useful for the optimization of DC-based vaccines.

Rare coding variants pinpoint genes that control human hematological traits

The identification of rare coding or splice site variants remains the most straightforward strategy to link genes with human phenotypes. Here, we analyzed the association between 137,086 rare (minor allele frequency (MAF) <1%) coding or splice site variants and 15 hematological traits in up to 308,572 participants. We found 56 such rare coding or splice site variants at P<5x10-8, including 31 that are associated with a blood-cell phenotype for the first time. All but one of these 31 new independent variants map to loci previously implicated in hematopoiesis by genome-wide association studies (GWAS). This includes a rare splice acceptor variant (rs146597587, MAF = 0.5%) in interleukin 33 (IL33) associated with reduced eosinophil count (P = 2.4x10-23), and lower risk of asthma (P = 2.6x10-7, odds ratio [95% confidence interval] = 0.56 [0.45-0.70]) and allergic rhinitis (P = 4.2x10-4, odds ratio = 0.55 [0.39-0.76]). The single new locus identified in our study is defined by a rare p.Arg172Gly missense variant (rs145535174, MAF = 0.05%) in plasminogen (PLG) associated with increased platelet count (P = 6.8x10-9), and decreased D-dimer concentration (P = 0.018) and platelet reactivity (P<0.03). Finally, our results indicate that searching for rare coding or splice site variants in very large sample sizes can help prioritize causal genes at many GWAS loci associated with complex human diseases and traits.

CXCL4 Exposure Potentiates TLR-Driven Polarization of Human Monocyte-Derived Dendritic Cells and Increases Stimulation of T Cells

Chemokines have been shown to play immune-modulatory functions unrelated to steering cell migration. CXCL4 is a chemokine abundantly produced by activated platelets and immune cells. Increased levels of circulating CXCL4 are associated with immune-mediated conditions, including systemic sclerosis. Considering the central role of dendritic cells (DCs) in immune activation, in this article we addressed the effect of CXCL4 on the phenotype and function of monocyte-derived DCs (moDCs). To this end, we compared innate and adaptive immune responses of moDCs with those that were differentiated in the presence of CXCL4. Already prior to TLR- or Ag-specific stimulation, CXCL4-moDCs displayed a more matured phenotype. We found that CXCL4 exposure can sensitize moDCs for TLR-ligand responsiveness, as illustrated by a dramatic upregulation of CD83, CD86, and MHC class I in response to TLR3 and TLR7/8-agonists. Also, we observed a markedly increased secretion of IL-12 and TNF-α by CXCL4-moDCs exclusively upon stimulation with polyinosinic-polycytidylic acid, R848, and CL075 ligands. Next, we analyzed the effect of CXCL4 in modulating DC-mediated T cell activation. CXCL4-moDCs strongly potentiated proliferation of autologous CD4+ T cells and CD8+ T cells and production of IFN-γ and IL-4, in an Ag-independent manner. Although the internalization of Ag was comparable to that of moDCs, Ag processing by CXCL4-moDCs was impaired. Yet, these cells were more potent at stimulating Ag-specific CD8+ T cell responses. Together our data support that increased levels of circulating CXCL4 may contribute to immune dysregulation through the modulation of DC differentiation.

N-dihydrogalactochitosan as a potent immune activator for dendritic cells

Immunotherapy has become one of the fastest growing areas of cancer research. A promising in situ autologous cancer vaccine (inCVAX) uses a novel immune activator, N-dihydrogalactochitosan (GC), that possesses the ability to stimulate dendritic cells (DC). inCVAX is a combination treatment procedure involving treatment of the tumor with a thermal near-infrared laser to liberate whole cell tumor antigens, followed by injection of GC (a glucosamine polymer with galactose attached to the amino groups) into the treated tumor thereby inducing a systemic antitumor immune response. Regression of both the treated tumor and distant untreated metastases has been observed in both nonclinical and clinical settings following inCVAX. We studied the stimulatory action of GC on relatively immature DCs (DC2.4 cell line) in vitro. GC at 1 mg/mL was a potent stimulator for DC with limited toxicity, giving increased expression of major histocompatibility complex class 2, CD80, and CD11c. Confocal imaging also revealed qualitatively increased uptake of antigen (Texas red-labeled ovalbumin) by DCs after the introduction of GC. To visualize cellular uptake, GC was conjugated with FITC-fluorophore revealing its cellular internalization after 8 hours. In some cases GC was more effective than the toxic TLR4 agonist, lipopolysaccharide. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 963-972, 2017.

Platelet-Related Variants Identified by Exomechip Meta-analysis in 157,293 Individuals

Platelet production, maintenance, and clearance are tightly controlled processes indicative of platelets' important roles in hemostasis and thrombosis. Platelets are common targets for primary and secondary prevention of several conditions. They are monitored clinically by complete blood counts, specifically with measurements of platelet count (PLT) and mean platelet volume (MPV). Identifying genetic effects on PLT and MPV can provide mechanistic insights into platelet biology and their role in disease. Therefore, we formed the Blood Cell Consortium (BCX) to perform a large-scale meta-analysis of Exomechip association results for PLT and MPV in 157,293 and 57,617 individuals, respectively. Using the low-frequency/rare coding variant-enriched Exomechip genotyping array, we sought to identify genetic variants associated with PLT and MPV. In addition to confirming 47 known PLT and 20 known MPV associations, we identified 32 PLT and 18 MPV associations not previously observed in the literature across the allele frequency spectrum, including rare large effect (FCER1A), low-frequency (IQGAP2, MAP1A, LY75), and common (ZMIZ2, SMG6, PEAR1, ARFGAP3/PACSIN2) variants. Several variants associated with PLT/MPV (PEAR1, MRVI1, PTGES3) were also associated with platelet reactivity. In concurrent BCX analyses, there was overlap of platelet-associated variants with red (MAP1A, TMPRSS6, ZMIZ2) and white (PEAR1, ZMIZ2, LY75) blood cell traits, suggesting common regulatory pathways with shared genetic architecture among these hematopoietic lineages. Our large-scale Exomechip analyses identified previously undocumented associations with platelet traits and further indicate that several complex quantitative hematological, lipid, and cardiovascular traits share genetic factors.

Characterization of the Expression and Function of the C-Type Lectin Receptor CD302 in Mice and Humans Reveals a Role in Dendritic Cell Migration

C-type lectin receptors play important roles in immune cell interactions with the environment. We described CD302 as the simplest, single domain, type I C-type lectin receptor and showed it was expressed mainly on the myeloid phagocytes in human blood. CD302 colocalized with podosomes and lamellopodia structures, so we hypothesized that it played a role in cell adhesion or migration. In this study, we used mouse models to obtain further insights into CD302 expression and its potential immunological function. Mouse CD302 transcripts were, as in humans, highest in the liver, followed by lungs, lymph nodes (LN), spleen, and bone marrow. In liver, CD302 was expressed by hepatocytes, liver sinusoidal endothelial cells, and Kupffer cells. A detailed analysis of CD302 transcription in mouse immune cells revealed highest expression by myeloid cells, particularly macrophages, granulocytes, and myeloid dendritic cells (mDC). Interestingly, 2.5-fold more CD302 was found in migratory compared with resident mDC populations and higher CD302 expression in mouse M1 versus M2 macrophages was also noteworthy. CD302 knockout (CD302KO) mice were generated. Studies on the relevant immune cell populations revealed a decrease in the frequency and numbers of migratory mDC within CD302KO LN compared with wild-type LN. In vitro studies showed CD302KO and wild-type DC had an equivalent capacity to undergo maturation, prime T cells, uptake Ags, and migrate toward the CCL19/CCL21 chemokines. Nevertheless, CD302KO migratory DC exhibited reduced in vivo migration into LN, confirming a functional role for CD302 in mDC migration.

1H, 13C and 15N resonance assignments of human DCL-1 (CD302) extracellular domain

DCL-1 (CD302) is a single-pass type one transmembrane protein which is predominantly expressed on myeloid cell lines. It possess the ability of endocytosis and is assumed to play a role in cell adhesion and migration. It has been also connected to several illnesses but more on the level of mRNA than on the protein expression level. More interestingly it is alternatively expressed in the form of a fusion protein with another single-pass type one transmembrane protein DEC205 (CD205) which is normally involved in antigen-uptake and endocytosis. The fusion protein has been assigned to have altered function compared to the wild type proteins. We have performed NMR structural analysis of the 16.2 kDa extracellular domain of DCL-1 to get a better insight onto this molecule. We have been able to assign nearly 97 % of resonance frequencies for the (15)N and (13)C labeled recombinant protein. The assignments have been deposited into Biological Magnetic Resonance Data Bank under the accession number 25802.

Targeting dendritic cells: a promising strategy to improve vaccine effectiveness

Dendritic cell (DC) targeting is a novel strategy to enhance vaccination efficacy. This approach is based on the in situ delivery of antigen via antibodies that are specific for endocytic receptors expressed at the surface of DCs. Here we review the complexity of the DC subsets and the antigen presentation pathways that need to be considered in the settings of DC targeting. We also summarize current knowledge about antigen delivery to DCs via DEC-205, Clec9A and Clec12A, receptor targets that strongly enhance cellular and humoral immune responses. Finally, we discuss the intracellular trafficking criteria of the targeted receptors that may impact their effectiveness as DC targets.

Investigation and optimization of formulation parameters on preparation of targeted anti-CD205 tailored PLGA nanoparticles

The purpose of this study was to assess the effect of various formulation parameters on anti-CD205 antibody decorated poly(d, l-lactide co-glycolide) (PLGA) nanoparticles (NPs) in terms of their ability to target dendritic cells (DCs). In brief, emulsification solvent evaporation technique was adapted to design NP formulations using two different viscosity grades (low and high) of both ester and carboxylic acid terminated PLGA. Incorporation of ligand was achieved following physical adsorption or chemical conjugation processes. The physicochemical characterizations of formulations were executed to assess the effects of different solvents (chloroform and ethyl acetate), stabilizer percentage, polymer types, polymer viscosities, ligand-NP bonding types, cross-linkers, and cryoprotectants (sucrose and trehalose). Modification of any of these parameters shows significant improvement of physicochemical properties of NPs. Ethyl acetate was the solvent of choice for the formulations to ensure better emulsion formation. Infrared spectroscopy confirmed the presence of anti-CD205 antibody in the NP formulation. Finally, cytotoxicity assay confirmed the safety profile of the NPs for DCs. Thus, ligand modified structurally concealed PLGA NPs is a promising delivery tool for targeting DCs in vivo.

Acute brief heat stress in late gestation alters neonatal calf innate immune functions

Heat stress, as one of the environmental stressors affecting the dairy industry, compromises the cow milk production, immune function, and reproductive system. However, few studies have looked at how prenatal heat stress (HS) affects the offspring. The objective of this study was to evaluate the effect of HS during late gestation on calf immunity. Calves were born to cows exposed to evaporative cooling (CT) or HS (cyclic 23-35°C) for 1 wk at 3 wk before calving. Both bull and heifer calves (CT, n=10; HS, n=10) were housed in similar environmental temperatures after birth. Both CT and HS calves received 3.78 L of pooled colostrum within 12 h after birth and were fed the same diet throughout the study. In addition to tumor necrosis factor α, IL-1β, IL-1 receptor antagonist (IL-1RA), and toll-like receptor (TLR)2, and TLR4 mRNA expression, the expression of CD14(+) and CD18(+) cells, and DEC205(+) dendritic cells were determined in whole blood samples at d 0, 3, 7, 14, 21, and 28. The neutrophil to lymphocyte ratio, differential cell counts, and the hematocrit were also determined. During late gestation, the HS cows had greater respiration rates, rectal temperatures, and tended to spend more time standing compared with the CT cows. The HS calves had less expression of tumor necrosis factor-α and TLR2 and greater levels of IL-1β, IL-1RA, and TLR4 compared with CT calves. The HS calves also had a greater percentage of CD18(+) cells compared with the CT calves. Additionally, a greater percentage of neutrophils and lesser percentage of lymphocytes were in the HS calves compared with the CT calves. The results indicate that biomarkers of calves' immunity are affected in the first several weeks after birth by HS in the dam during late gestation.

Criteria for dendritic cell receptor selection for efficient antibody-targeted vaccination

Ab-targeted vaccination involves targeting a receptor of choice expressed by dendritic cells (DCs) with Ag-coupled Abs. Currently, there is little consensus as to which criteria determine receptor selection to ensure superior Ag presentation and immunity. In this study, we investigated parameters of DC receptor internalization and determined how they impact Ag presentation outcomes. First, using mixed bone marrow chimeras, we established that Ag-targeted, but not nontargeted, DCs are responsible for Ag presentation in settings of Ab-targeted vaccination in vivo. Next, we analyzed parameters of DEC205 (CD205), Clec9A, CD11c, CD11b, and CD40 endocytosis and obtained quantitative measurements of internalization speed, surface turnover, and delivered Ag load. Exploiting these parameters in MHC class I (MHC I) and MHC class II (MHC II) Ag presentation assays, we showed that receptor expression level, proportion of surface turnover, or speed of receptor internalization did not impact MHC I or MHC II Ag presentation efficiency. Furthermore, the Ag load delivered to DCs did not correlate with the efficiency of MHC I or MHC II Ag presentation. In contrast, targeting Ag to CD8(+) or CD8(-) DCs enhanced MHC I or MHC II Ag presentation, respectively. Therefore, receptor expression levels, speed of internalization, and/or the amount of Ag delivered can be excluded as major determinants that dictate Ag presentation efficiency in setting of Ab-targeted vaccination.

Imbalance between CD205 and CD80/CD86 in dendritic cells in patients with immune thrombocytopenia

INTRODUCTION

CD205(DEC-205), a tolerance-associated receptor, is a member of the macrophage mannose receptor family of C-type lectin receptors. Antigen uptake via CD205 induces regulatory T cells, thereby regulating peripheral immune tolerance. However, the contribution of CD205 to autoimmune diseases has not been elucidated. Immune thrombocytopenia (ITP) is an autoimmune disorder characterized by overdestruction of platelets. A previous study by the present authors found that CD205 expression in dendritic cells (DCs) was upregulated during induction of immune tolerance in patients with ITP.

METHODS

CD205 expression in monocyte-derived DCs and spleens from patients with ITP was analysed prior to and after high-dose dexamethasone (HD-DXM) treatment. Expression of CD80, CD86 and HLA-DR was also analysed in order to identify and define the maturation status of the DCs more precisely.

RESULTS

In patients with ITP, CD205 expression was found to be significantly decreased in DCs, and rare or absent in the border region of the spleen. However, the expression of CD80 and CD86 was increased in both monocyte-derived DCs and spleens in patients with ITP compared with controls. HD-DXM treatment may upregulate CD205 expression and downregulate CD80/CD86 expression, then rebalance the expression of CD205 and CD80/CD86 in DCs in patients with ITP.

CONCLUSION

Imbalance between CD205 and CD80/CD86 may contribute to the development of ITP. Therapies that aim to restore the balance between CD205 and CD80/CD86 may help to re-establish tolerance in patients with ITP.

Macrophage mannose receptor-specific gene delivery vehicle for macrophage engineering

Macrophages are the most plastic cells in the hematopoietic system and they exhibit great functional diversity. They have been extensively applied in anti-inflammatory, anti-fibrotic and anti-cancer therapies. However, the application of macrophages is limited by the efficiency of their engineering. The macrophage mannose receptor (MMR, CD206), a C-type lectin receptor, is ubiquitously expressed on macrophages and has a high affinity for mannose oligosaccharides. In the present study, we developed a novel non-viral vehicle with specific affinity for MMR. Mannan was cationized with spermine at a grafted ratio of ∼12% to deliver DNA and was characterized as a stable system for delivery. This spermine-mannan (SM)-based delivery system was evaluated as a biocompatible vehicle with superior transfection efficiency on murine macrophages, up to 28.5-fold higher than spermine-pullulan, 11.5-fold higher than polyethylenimine and 3.0-fold higher than Lipofectamine™ 2000. We confirmed that the SM-based delivery system for macrophages transfection was MMR-specific and we described the intracellular transport of the delivery system. To our knowledge, this is the first study using SM to demonstrate a mannose receptor-specific gene delivery system, thereby highlighting the potential of a novel specific non-viral delivery vehicle for macrophage engineering.

Effects of ceftriaxone-induced intestinal dysbacteriosis on dendritic cells of small intestine in mice

Intestinal microflora plays a pivotal role in the development of the innate immune system and is essential in shaping adaptive immunity. Dysbacteriosis of intestinal microflora induces altered immune responses and results in disease susceptibility. Dendritic cells (DCs), the professional antigen-presenting cells, have gained increasing attention because they connect innate and adaptive immunity. They generate both immunity in response to stimulation by pathogenic bacteria and immune tolerance in the presence of commensal bacteria. However, few studies have examined the effects of intestinal dysbacteriosis on DCs. In this study, changes of DCs in the small intestine of mice under the condition of dysbacteriosis induced by ceftriaxone sodium were investigated. It was found that intragastric administration of ceftriaxone sodium caused severe dysteriosis in mice. Compared with controls, numbers of DCs in mice with dysbacteriosis increased significantly (P = 0.0001). However, the maturity and antigen-presenting ability of DCs were greatly reduced. In addition, there was a significant difference in secretion of IL-10 and IL-12 between DCs from mice with dysbacteriosis and controls. To conclude, ceftriaxone-induced intestinal dysbacteriosis strongly affected the numbers and functions of DCs. The present data suggest that intestinal microflora plays an important role in inducing and maintaining the functions of DCs and thus is essential for the connection between innate and adaptive immune responses.

Targeting antigens to dendritic cell receptors for vaccine development

Dendritic cells (DCs) are highly specialized antigen presenting cells of the immune system which play a key role in regulating immune responses. Depending on the method of antigen delivery, DCs stimulate immune responses or induce tolerance. As a consequence of the dual function of DCs, DCs are studied in the context of immunotherapy for both cancer and autoimmune diseases. In vaccine development, a major aim is to induce strong, specific T-cell responses. This is achieved by targeting antigen to cell surface molecules on DCs that efficiently channel the antigen into endocytic compartments for loading onto MHC molecules and stimulation of T-cell responses. The most attractive cell surface receptors, expressed on DCs used as targets for antigen delivery for cancer and other diseases, are discussed.

Granuloma cells in chronic inflammation express CD205 (DEC205) antigen and harbor proliferating T lymphocytes: similarity to antigen-presenting cells

Granulomas are classified as immune or foreign body granulomas. Of these, the immune granulomas, a hallmark of granulomatous inflammation, are closely related to cell-mediated immune responses. The aim of the present study is to characterize immune granuloma cells in 33 patients with granulomatous inflammation focusing on the expression of CD205 (DEC205), a cell surface marker of antigen presenting cells, and their spatial relationship to T cells. CD205 was frequently expressed by immune granuloma cells, in contrast to foreign body granuloma cells that lacked CD205 expression. T cells were not only distributed in a lymphocyte collar around the granuloma, but also present among the granuloma cells (termed 'intra-granuloma T cells'). Intra-granuloma T cells stained positive for Ki-67 (median positivity = 9.4%) by double immunostaining for CD3 and Ki-67. This indicated the presence of proliferative stimuli within the granuloma that could activate the intra-granuloma T cells. The labeling index of Ki-67 in intra-granuloma T cells was significantly higher than that of T cells in the lymphocyte collar (P < 0.0001) or T cells in the T cell zone (paracortex) of chronic tonsillitis or reactive lymphadenitis (P = 0.002). These data indicate a close similarity between immune granulomas and antigen presenting cells.

The specialized roles of immature and mature dendritic cells in antigen cross-presentation

Exogenous antigen cross-presentation is integral to the stimulation of cytotoxic T-lymphocytes against viruses and tumors. Central to this process are dendritic cells (DCs), which specialize in cross-presentation. DCs may be considered to exist in two radically different states of activation, generally referred to as immature and mature. In each of these states, the cell has a series of separate and specialized abilities for the induction of T-cell immunity. In the immature state, the DC is adept in surveying the periphery, acquiring and storing antigen, but has a limited capacity for direct T-cell activation. During a brief and defined window of time following DC stimulation, nearly every aspect of antigen handling changes, as it transitions from an entity focused on protein preservation to one capable of efficient cross-presentation. It is this time period and the underlying molecular mechanisms active here, which form the core of our studies on cross-presentation.

Monocytes differentiation upon treatment with a peptide corresponding to the C-terminus of activated T cell-expressed Tirc7 protein

Atp6v0a3 gene encodes for two alternative products, Tirc7 and a3 proteins, which are differentially expressed in activated T cells and resorbing osteoclasts, respectively. Tirc7 plays a central role in T cell activation, while a3 protein is critical for osteoclast-mediated bone matrix resorption. Based on the large body of evidences documenting the relationships between T cells and osteoclasts, we hypothesized that the extracellular C-terminus of Tirc7 protein could directly interact with osteoclast precursor cells. To address this issue, we performed the molecular cloning of a mouse Atp6v0a3 cDNA segment encoding the last 40 amino acids of Tirc7 protein, and we used this peptide as a ligand added to mouse osteoclast precursor cells. We evidenced that Tirc7-Cter peptide induced the differentiation of RAW264.7 cells into osteoclast-like cells, stimulated an autocrine/paracrine regulatory loop potentially involved in osteoclastic differentiation control, and strongly up-regulated F4/80 protein expression within multinucleated osteoclast-like cells. Using a mouse bone marrow-derived CD11b(+) cell line, or total bone marrow primary cells, we observed that similarly to Rankl, Tirc7-Cter peptide induced the formation of TRACP-positive large multinucleated cells. At last, using mouse primary monocytes purified from total bone marrow, we determined that Tirc7-Cter peptide induced the appearance of small multinucleated cells (3-4 nuclei), devoid of resorbing activity, and which displayed modulations of dendritic cell marker genes expression. In conclusion, we report for the first time on biological effects mediated by a peptide corresponding to the C-terminus of Tirc7 protein, which interfere with monocytic differentiation pathways.

The C-type lectin receptor CLEC9A mediates antigen uptake and (cross-)presentation by human blood BDCA3+ myeloid dendritic cells

CLEC9A is a recently discovered C-type lectin receptor involved in sensing necrotic cells. In humans, this receptor is selectively expressed by BDCA3+ myeloid dendritic cells (mDCs), which have been proposed to be the main human cross-presenting mDCs and may represent the human homologue of murine CD8+ DCs. In mice, it was demonstrated that antigens delivered with antibodies to CLEC9A are presented by CD8+ DCs to both CD4+ and CD8+ T cells and induce antitumor immunity in a melanoma model. Here we assessed the ability of CLEC9A to mediate antigen presentation by human BDCA3+ mDCs, which represent < 0.05% of peripheral blood leukocytes. We demonstrate that CLEC9A is only expressed on immature BDCA3+ mDCs and that cell surface expression is lost after TLR-mediated maturation. CLEC9A triggering via antibody binding rapidly induces receptor internalization but does not affect TLR-induced cytokine production or expression of costimulatory molecules. More importantly, antigens delivered via CLEC9A antibodies to BDCA3+ mDCs are presented by both MHC class I (cross-presentation) and MHC class II to antigen-specific T cells. We conclude that CLEC9A is a promising target for in vivo antigen delivery in humans to increase the efficiency of vaccines against infectious or malignant diseases.

Localization of sporadic neuroendocrine tumors by gene expression analysis of their metastases

A characteristic of human gastroenteropancreatic neuroendocrine tumors (GEP-NET) is a minute unobtrusive primary tumor which often cannot be detected by common physical examinations. It therefore remains unidentified until the tumor has spread and space-occupying metastases cause clinical symptoms leading to diagnosis. Cases in which the primary cannot be located are referred to as NET with CUP-syndrome (cancer of unknown primary syndrome). With the help of array-CGH (comparative genomic hybridization, Agilent 105K) and gene expression analysis (Agilent 44K), microdissected primaries and their metastases were compared to identify up- and down-regulated genes which can be used as a marker for tumor progression. In a next analysis step, a hierarchical clustering of 41.078 genes revealed three genes [C-type lectin domain family 13 member A (CD302), peptidylprolyl isomerase containing WD40 repeat (PPWD1) and abhydrolase domain containing 14B (ABHD14B)] which expression levels can categorize the metastases into three groups depending on the localization of their primary. Because cancer therapy is dependent on the localization of the primary, the gene expression level of these three genes are promising markers to unravel the CUP syndrome in NET.

DEC-205 mediates antigen uptake and presentation by both resting and activated human plasmacytoid dendritic cells

DEC-205 is a type I C-type lectin receptor (CLR) that is expressed on various APC subsets and has been suggested to bind necrotic and apoptotic cells. Here we study DEC-205 characteristics in plasmacytoid DCs (pDCs) obtained from healthy individuals and assess its ability to mediate antigen presentation by isolating sufficient numbers of pDCs from apheresis material obtained from stage III/IV melanoma patients. The results demonstrate that DEC-205 is expressed on human pDCs. Internalization of DEC-205 after antibody ligation is clathrin- and dynamin-dependent as it is blocked by hypertonic shock or by inhibition of dynamin activity. Antibody targeting to DEC-205 does not affect TLR-induced expression levels of co-stimulatory and MHC molecules, but clearly impairs TLR-induced IFN-α secretion by 40%. We observed that TLR-mediated signaling increases DEC-205 expression levels without affecting receptor internalization. Moreover, human pDCs retained the capacity to present antigens via DEC-205 following TLR activation.

Targeting with oligomannose-coated liposomes promotes maturation and splenic trafficking of dendritic cells in the peritoneal cavity

In previous studies, we have shown that oligomannose-coated liposomes (OMLs) have a strong adjuvant effect in inducing T-helper 1 (Th1) immune responses and cytotoxic T cells specific for the encased antigen. In the present study, we demonstrate that preferential uptake of OMLs by DCs and subsequent DC maturation and splenic trafficking may be correlated with the adjuvant effect of OMLs. About 3% of resting murine peritoneal cells are CD11b(dull)CD11c(+) cells, which express MHC class II and CD86, and about 30% are CD11b(high)CD11c(-) cells, which express F4/80 and CD14. This indicates that these cells are resident peritoneal DCs and monocytes/macrophages, respectively. Both types of cells rapidly took up OMLs in the peritoneal cavity, but only CD11b(dull)CD11c(+) cells produced interleukin (IL)-12 in response to OML uptake. IL-6 was not produced by either type of cells. The expression levels of CD205 and CCR7, which are markers of cell maturity in murine DCs, were upregulated in CD11b(dull)CD11c(+) cells obtained from OML-treated mice. In addition, CD11b(dull)CD11c(+) cells with ingested OMLs were found in the spleen 18 h after intraperitoneal administration of OMLs. These results indicate that OMLs can be used as a vehicle for delivery of antigens to DCs and as an adjuvant to promote DC maturation, activation, and trafficking into lymphoid organs, thereby eliciting a Th1 immune response.

DC-specific ICAM-3-grabbing nonintegrin mediates internalization of HIV-1 into human podocytes

Human immunodeficiency virus (HIV)-1 has been demonstrated to contribute to the pathogenesis of HIV-associated nephropathy. In renal biopsy studies, podocytes have been reported to be infected by HIV-1. However, the mechanism involved in HIV-1 internalization into podocytes is not clear. In the present study, we evaluated the occurrence of HIV-1 internalization into conditionally immortalized human podocytes and the mechanism involved. Human podocytes rapidly internalized R5 and X4 HIV-1 primary strains via an endocytosis-dependent pathway, without establishing a productive infection. The HIV-1 internalization was dendritic cell-specific ICAM-3-grabbing nonintegrin (DC-SIGN) receptor mediated. The role of DC-SIGN was confirmed by using specific blocking antibodies and transfection with small interfering (si) RNA/DC-SIGN. Since podocyte HIV-1 trafficking was not altered by pH-modulating agents, it appeared that HIV-1 routing occurred through nonacid vesicular compartments. Interestingly, transfection of podocytes with neither siRNA/caveolin-1 nor siRNA/clathrin heavy chain inhibited podocyte viral accumulation. Thus it appears that clathrin-coated vesicles and caveosomes may not be contributing to HIV-1-associated membrane traffic.

Characterization of porcine CD205

Dendritic cells express a type cell-surface receptor, CD205 that plays a role in antigen capture and delivery to the endocytic pathway. Besides DCs, high CD205 expression is also detected on thymic epithelial cells but B cells, macrophages, and T cells have limited or no expression. CD205 has been characterized in several animal species except swine. The aim of this work was to characterize porcine CD205 and mRNA expression on different cells and tissues involved in immune responses. A complete porcine CD205 sequence of 5175bp was obtained from porcine thymus cDNA by PCR gene-walking strategy and this gene encoded a protein of 1723 amino acids. The multi-domain structure reported for murine, human, and bovine CD205 was also conserved in porcine with an overall amino acid identity of 74, 81, and 85%, respectively. Quantitative RT-PCR analysis of the CD205 mRNA profiles in normal porcine tissues and cells showed that thymus and Langerhans cells expressed the highest levels. Further characterization of porcine CD205 will lead to better understanding of the role of this receptor and development of contemporary strategies for antigen targeting to DCs in swine.

Targeting of DEC-205 on human dendritic cells results in efficient MHC class II-restricted antigen presentation

The use of dendritic cells (DCs) in therapeutic cancer vaccination requires their loading with tumor-specific antigen(s). DEC-205, a phagocytosis receptor mediating antigen uptake, is associated with CD8(+) T-cell responses in mice. Here we fused an anti-DEC-205scFv to an HLA-DP4-restricted epitope from the tumor antigen MAGE-A3, and examined the suitability and efficacy of DEC-205 to deliver a helper epitope to human monocyte-derived DCs (moDCs). The construct specifically bound DEC-205 on human moDCs without negative impact on DC phenotype and function. We measured antigen presentation with specific autologous CD4(+) T cells, generated by TCR-RNA transfection. DEC-205 targeting resulted in significant major histocompatibility complex class II-restricted antigen presentation, and was superior to loading DCs by electroporation of mRNA encoding endosome-targeted MAGE-A3-DCLAMP or by direct peptide pulsing. Anti-DEC-205scFv-MAGE-A3 was presented 100 times more efficiently than the control constructs. DC maturation before or during incubation with anti-DEC-205scFv-MAGE-A3 reduced the interleukin-10/interleukin-2 ratio. Moreover, we successfully applied the DEC-205 targeting strategy to moDCs from malignant melanoma patients. Again, DEC-205-targeted mature DCs (mDCs) presented the antigen more efficiently than peptide-pulsed DCs and maintained their stimulatory capacity after cryoconservation. Thus, DEC-205 targeting represents a feasible and effective method to deliver helper epitopes to DCs in anticancer vaccine strategies, which may also be suitable for DC targeting in vivo.

CD205 (DEC-205): a recognition receptor for apoptotic and necrotic self

CD205 is an endocytic receptor that is expressed at high levels by cortical thymic epithelial cells and by dendritic cell (DC) subsets, including the splenic CD8+ DC population that is responsible for cross-presentation of apoptotic cell-derived antigens. Antigen endocytosed via CD205 enters the MHC class I and MHC class II antigen presentation pathways and is subsequently presented to both CD4+ and CD8+ T cells. Despite the known role of CD205 in antigen uptake, the nature of the ligands bound by CD205 has not been determined, and most studies have relied on the use of monoclonal antibodies as surrogate ligands. To go beyond this approach, we created a panel of CD205-IgG fusion proteins spanning the extracellular portion of CD205 and used these to identify the physiological distribution of CD205 ligands. Our data demonstrate that two areas of the CD205 molecule, within C-type lectin-like domains (CTLDs) 3+4 and 9+10, recognise ligands expressed during apoptosis and necrosis of multiple cell types, and are additionally expressed by live cells of the dendritic cell line DC2.4. Thus, CD205 acts as a recognition receptor for dying cells, potentially providing an important pathway for the uptake of self-antigen in intrathymic and peripheral tolerance.