Development of Th1-inducing capacity in myeloid dendritic cells requires environmental instruction

Innate cells and STAT1-dependent signals orchestrate vaccine-induced protection against invasive Cryptococcus infection

Fungal pathogens are underappreciated causes of significant morbidity and mortality worldwide. In previous studies, we determined that a heat-killed, Cryptococcus neoformans fbp1-deficient strain (HK-fbp1) is a potent vaccine candidate. We determined that vaccination with HK-fbp1 confers protective immunity against lethal Cryptococcosis in an interferon γ (IFNγ)-dependent manner. In this study, we set out to uncover cellular sources and relevant targets of the protective effects of IFNγ in response to the HK-fbp1 vaccine. We found that early IFNγ production peaks at day 3 and that monocytes and neutrophils are important sources of this cytokine after vaccination. Neutralization of IFNγ at day 3 results in impaired CCR2+ monocyte recruitment and reduced differentiation into monocyte-derived dendritic cells (Mo-DC). In turn, depletion of CCR2+ cells prior to immunization results in impaired activation of IFNγ-producing CD4 and CD8 T cells. Thus, monocytes are important targets of innate IFNγ and help promote further IFNγ production by lymphocytes. We employed monocyte-fate mapper and conditional STAT1 knockout mice to uncover that STAT1 activation in CD11c+ cells, including alveolar macrophages, Mo-DCs, and monocyte-derived macrophages (Mo-Mac) is essential for HK-fbp1 vaccine-induced protection. Altogether, our aggregate findings suggest critical roles for innate cells as orchestrators of vaccine-induced protection against Cryptococcus infection.IMPORTANCEThe number of patients susceptible to invasive fungal infections across the world continues to rise at an alarming pace yet current antifungal drugs are often inadequate. Immune-based interventions and novel antifungal vaccines hold the promise of significantly improving patient outcomes. In previous studies, we identified a Cryptococcus neoformans mutant strain (Fbp1-deficient) as a potent, heat-inactivated vaccine candidate capable of inducing homologous and heterologous antifungal protection. In this study, we used a combination of methods together with a cohort of conditional knockout mouse strains to interrogate the roles of innate cells in the orchestration of vaccine-induced antifungal protection. We uncovered novel roles for neutrophils and monocytes as coordinators of a STAT1-dependent cascade of responses that mediate vaccine-induced protection against invasive cryptococcosis. This new knowledge will help guide the future development of much-needed antifungal vaccines.

Factor of time in dendritic cell (DC) maturation: short-term activation of DCs significantly improves type 1 cytokine production and T cell responses

Dendritic cells (DCs) have been intensively studied in correlation to tumor immunology and for the development DC-based cancer vaccines. Here, we present the significance of the temporal aspect of DC maturation for the most essential subsequent timepoint, namely at interaction with responding T cells or after CD40-Ligand restimulation. Mostly, DC maturation is still being achieved by activation processes which lasts 24 h to 48 h. We hypothesized this amount of time is excessive from a biological standpoint and could be the underlying cause for functional exhaustion. Indeed, shorter maturation periods resulted in extensive capacity of monocyte-derived DCs to produce inflammatory cytokines after re-stimulation with CD40-Ligand. This effect was most evident for the primary type 1 polarizing cytokine, IL-12p70. This capacity reached peak at 6 h and dropped sharply with longer exposure to initial maturation stimuli (up to 48 h). The 6 h maturation protocol reflected superiority in subsequent functionality tests. Namely, DCs displayed twice the allostimulatory capacity of 24 h- and 48 h-matured DCs. Similarly, type 1 T cell response measured by IFN-γ production was 3-fold higher when CD4+ T cells had been stimulated with shortly matured DC and over 8-fold greater in case of CD8+ T cells, compared to longer matured DCs. The extent of melanoma-specific CD8+ cytotoxic T cell induction was also greater in case of 6 h DC maturation. The major limitation of the study is that it lacks in vivo evidence, which we aim to examine in the future. Our findings show an unexpectedly significant impact of temporal exposure to activation signals for subsequent DC functionality, which we believe can be readily integrated into existing knowledge on in vitro/ex vivo DC manipulation for various uses. We also believe this has important implications for DC vaccine design for future clinical trials.

Unlocking Dendritic Cell-Based Vaccine Efficacy through Genetic Modulation-How Soon Is Now?

The dendritic cell (DC) vaccine anti-cancer strategy involves tumour-associated antigen loading and maturation of autologous ex vivo cultured DCs, followed by infusion into the cancer patient. This strategy stemmed from the idea that to induce a robust anti-tumour immune response, it was necessary to bypass the fundamental immunosuppressive mechanisms of the tumour microenvironment that dampen down endogenous innate immune cell activation and enable tumours to evade immune attack. Even though the feasibility and safety of DC vaccines have long been confirmed, clinical response rates remain disappointing. Hence, the full potential of DC vaccines has yet to be reached. Whether this cellular-based vaccination approach will fully realise its position in the immunotherapy arsenal is yet to be determined. Attempts to increase DC vaccine immunogenicity will depend on increasing our understanding of DC biology and the signalling pathways involved in antigen uptake, maturation, migration, and T lymphocyte priming to identify amenable molecular targets to improve DC vaccine performance. This review evaluates various genetic engineering strategies that have been employed to optimise and boost the efficacy of DC vaccines.

A recombinant rabies virus chimera expressing the DC-targeting molecular MAB2560 shows enhanced vaccine immunogenicity through activation of dendritic cells

BACKGROUND

Rabies, caused by the rabies virus (RABV), is an ancient and neglected zoonotic disease posing a large public health threat to humans and animals in developing countries. Immunization of animals with a rabies vaccine is the most effective way to control the epidemic and the occurrence of the disease in humans. Therefore, the development of cost-effective and efficient rabies vaccines is urgently needed. The activation of dendritic cells (DCs) is known to play an important role in improving the host immune response induced by rabies vaccines.

METHODOLOGY/PRINCIPAL FINDINGS

In this study, we constructed a recombinant virus, rCVS11-MAB2560, based on the reverse genetic system of the RABV CVS11 strain. The MAB2560 protein (a DC-targeting molecular) was chimeric expressed on the surface of the viral particles to help target and activate the DCs when this virus was used as inactivated vaccine. Our results demonstrated that inactivated rCVS11-MAB2560 was able to promote the recruitment and/or proliferation of DC cells, T cells and B cells in mice, and induce good immune memory after two immunizations. Moreover, the inactivated recombinant virus rCVS11-MAB2560 could produce higher levels of virus-neutralizing antibodies (VNAs) in both mice and dogs more quickly than rCVS11 post immunization.

CONCLUSIONS/SIGNIFICANCE

In summary, the recombinant virus rCVS11-MAB2560 chimeric-expressing the molecular adjuvant MAB2560 can stimulate high levels of humoral and cellular immune responses in vivo and can be used as an effective inactivated rabies vaccine candidate.

An inactivated recombinant rabies virus chimerically expressed RBD induces humoral and cellular immunity against SARS-CoV-2 and RABV

Many studies suggest that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can infect various animals and transmit among animals, and even to humans, posing a threat to humans and animals. There is an urgent need to develop inexpensive and efficient animal vaccines to prevent and control coronavirus disease 2019 (COVID-19) in animals. Rabies virus (RABV) is another important zoonotic pathogen that infects almost all warm-blooded animals and poses a great public health threat. The present study constructed two recombinant chimeric viruses expressing the S1 and RBD proteins of the SARS-CoV-2 Wuhan01 strain based on a reverse genetic system of the RABV SRV9 strain and evaluated their immunogenicity in mice, cats and dogs. The results showed that both inactivated recombinant viruses induced durable neutralizing antibodies against SARS-CoV-2 and RABV and a strong cellular immune response in mice. Notably, inactivated SRV-nCoV-RBD induced earlier antibody production than SRV-nCoV-S1, which was maintained at high levels for longer periods. Inactivated SRV-nCoV-RBD induced neutralizing antibodies against both SARS-CoV-2 and RABV in cats and dogs, with a relatively broad-spectrum cross-neutralization capability against the SARS-CoV-2 pseudoviruses including Alpha, Beta, Gamma, Delta, and Omicron, showing potential to be used as a safe bivalent vaccine candidate against COVID-19 and rabies in animals.

Emerging hallmark of gliomas microenvironment in evading immunity: a basic concept

Background

Over the last decade, since clinical trials examining targeted therapeutics for gliomas have failed to demonstrate a meaningful increase in survival, the emphasis has recently been switched toward innovative techniques for modulating the immune response against tumors and their microenvironments (TME). Cancerous cells have eleven hallmarks which make it distinct from normal ones, among which is immune evasion. Immune evasion in glioblastoma helps it evade various treatment modalities.

Summary

Glioblastoma’s TME is composed of various array of cellular actors, ranging from peripherally derived immune cells to a variety of organ-resident specialized cell types. For example, the blood–brain barrier (BBB) serves as a selective barrier between the systemic circulation and the brain, which effectively separates it from other tissues. It is capable of blocking around 98% of molecules that transport different medications to the target tumor.

Objectives

The purpose of this paper is to offer a concise overview of fundamental immunology and how ‘clever’ gliomas avoid the immune system despite the discovery of immunotherapy for glioma.

Conclusions

Herein, we highlight the complex interplay of the tumor, the TME, and the nearby normal structures makes it difficult to grasp how to approach the tumor itself. Numerous researchers have found that the brain TME is a critical regulator of glioma growth and treatment efficacy.

Cryptococcus escapes host immunity: What do we know?

Cryptococcus is an invasive fungus that seriously endangers human life and health, with a complex and well-established immune-escaping mechanism that interferes with the function of the host immune system. Cryptococcus can attenuate the host’s correct recognition of the fungal antigen and escape the immune response mediated by host phagocytes, innate lymphoid cells, T lymphocytes, B lymphocytes with antibodies, and peripheral cytokines. In addition, the capsule, melanin, dormancy, Titan cells, biofilm, and other related structures of Cryptococcus are also involved in the process of escaping the host’s immunity, as well as enhancing the ability of Cryptococcus to infect the host.

A bacterium-like particle vaccine displaying Zika virus prM-E induces systemic immune responses in mice

The emergence of Zika virus (ZIKV) infection, which is unexpectedly associated with congenital defects, has prompted the development of safe and effective vaccines. The Gram-positive enhancer matrix-protein anchor (GEM-PA) display system has emerged as a versatile and highly effective platform for delivering target proteins in vaccines. In this study, we developed a bacterium-like particle vaccine, ZI-△-PA-GEM, based on the GEM-PA system. The fusion protein ZI-△-PA, which contains the prM-E-△TM protein of ZIKV (with a stem-transmembrane region deletion) and the protein anchor PA3, was expressed. The fusion protein was successfully displayed on the GEM surface to form ZI-△-PA-GEM. Moreover, the intramuscular immunization of BALB/c mice with ZI-△-PA-GEM combined with ISA 201 VG and poly(I:C) adjuvants induced durable ZIKV-specific IgG and protective neutralizing antibody responses. Potent B-cell/DC activation was also stimulated early after immunization. Notable, splenocyte proliferation, the secretion of multiple cytokines, T/B-cell activation and central memory T-cell responses were elicited. These data indicate that ZI-△-PA-GEM is a promising bacterium-like particle vaccine candidate for ZIKV.

Engaging innate immunity in HIV-1 cure strategies

Combination antiretroviral therapy (ART) can block multiple stages of the HIV-1 life cycle to prevent progression to AIDS in people living with HIV-1. However, owing to the persistence of a reservoir of latently infected CD4⁺ T cells, life-long ART is necessary to prevent viral rebound. One strategy currently under consideration for curing HIV-1 infection is known as 'shock and kill'. This strategy uses latency-reversing agents to induce expression of HIV-1 genes, allowing for infected cells to be cleared by cytolytic immune cells. The role of innate immunity in HIV-1 pathogenesis is best understood in the context of acute infection. Here, we suggest that innate immunity can also be used to improve the efficacy of HIV-1 cure strategies, with a particular focus on dendritic cells (DCs) and natural killer cells. We discuss novel latency-reversing agents targeting DCs as well as DC-based strategies to enhance the clearance of infected cells by CD8⁺ T cells and strategies to improve the killing activity of natural killer cells.

Meta-Analysis of Two Human RNA-seq Datasets to Determine Periodontitis Diagnostic Biomarkers and Drug Target Candidates

Periodontitis is a chronic inflammatory oral disease that affects approximately 42% of adults 30 years of age or older in the United States. In response to microbial dysbiosis within the periodontal pockets surrounding teeth, the host immune system generates an inflammatory environment in which soft tissue and alveolar bone destruction occur. The objective of this study was to identify diagnostic biomarkers and the mechanistic drivers of inflammation in periodontitis to identify drugs that may be repurposed to treat chronic inflammation. A meta-analysis comprised of two independent RNA-seq datasets was performed. RNA-seq analysis, signal pathway impact analysis, protein-protein interaction analysis, and drug target analysis were performed to identify the critical pathways and key players that initiate inflammation in periodontitis as well as to predict potential drug targets. Seventy-eight differentially expressed genes, 10 significantly impacted signaling pathways, and 10 hub proteins in periodontal gingival tissue were identified. The top 10 drugs that may be repurposed for treating periodontitis were then predicted from the gene expression and pathway data. The efficacy of these drugs in treating periodontitis has yet to be investigated. However, this analysis indicates that these drugs may serve as potential therapeutics to treat inflammation in gingival tissue affected by periodontitis.

Vaccines targeting angiogenesis in melanoma

Angiogenesis has a significant role in metastasis and progression of melanoma. Even small tumors may be susceptible to metastasis and hence lead to a worse outcome in patients with melanoma. One of the anti-angiogenic treatment approaches that is undergoing comprehensive study is specific immunotherapy. While tumor cells are challenging targets for immunotherapy due to their genetic instability and heterogeneity, endothelial cells (ECs) are genetically stable. Therefore, vaccines targeting angiogenesis in melanoma are appropriate choices that target both tumor cells and ECs while capable of inducing strong, anti-tumor immune responses with limited toxicity. The main targets of angiogenesis are VEGFs and their receptors but other potential targets have also been investigated, especially in preclinical studies. Various types of vaccines that target angiogenesis in melanoma have been studied including DNA, peptide, protein, dendritic cell-based, and endothelial cell vaccines. This review outlines a number of target antigens that are important for potential progress in developing vaccines for targeting angiogenesis in melanoma. We also discuss different types of vaccines that have been investigated, delivery mechanisms and popular adjuvants, and suggest ways to improve future clinical outcomes.

Mixed cultures of allogeneic dendritic cells are phenotypically and functionally stable - a potential for primary cell-based "off the shelf" product generation

Vaccination against tumors using antigen-pulsed dendritic cell (DC) vaccines has greatly evolved over the last decade, with hundreds of active human clinical trials well on the way. The use of an autologous source for DC-based vaccine therapeutics remains the obvious choice in the majority of clinical studies; however, novel evidence suggests that an allogeneic source of DCs can yield success if administered in the right context. One of the challenges facing successful DC vaccination protocols is the generation of large enough numbers of DCs intended for vaccination and standardization of these procedures. In addition, variations in the quality of DC vaccines due to donor-to-donor variation represent an important therapeutic factor. To this day it has not been shown whether DCs from different donors can readily co-exist within the same co-culture for the extended periods required for vaccine manufacture. We demonstrate that generation of allogeneic DC co-cultures, generated from multiple unrelated donors, allows the preservation of their phenotypical and functional properties in vitro for up to 72 hours. Therefore, in the case of an allogeneic vaccination approach, one could ensure large numbers of DCs generated from a primary cell source intended for multiple vaccinations. By generating large amounts of ex vivo manufactured DCs from multiple donors, this would represent the possibility to ensure sufficient amounts of equipotent “off the shelf” product that could e.g. be used for an entire cohort of patients within a study.

Amyloid β-induced Mesenteric Inflammation in an Alzheimer's Disease Transgenic Mouse Model

BACKGROUND

Alzheimer's disease (AD) is a neurodegenerative disorder histopathologically characterized by the accumulation of amyloid β (Aβ) peptides and inflammation associated with activated microglia. These features are well investigated in the central nervous system using AD-model mice; however, peripheral inflammation in these mice has not been investigated well.

OBJECTIVE

We evaluated the inflammatory responses, especially myeloid dendritic cells (mDCs), in peripheral lymphoid tissues in AD-model mice to determine their association with Aβ deposition.

METHODS

We collected lymphocytes from mesenteric lymphoid nodes (MLNs) and Peyer's patches (PPs) of 5×FAD transgenic mice used as an AD model. Lymphocytes were analyzed using a flow cytometer to characterize mDCs and T cells. Collected lymphocytes were treated with Aβ1-42 ex vivo to evaluate the inflammatory response.

RESULTS

We observed elevated levels of inflammatory cytokines and chemokines including interleukin (IL)-12 and macrophage inflammatory protein-1α in mDCs from MLNs and PPs and reduced levels of programmed death-ligand-1, an immunosuppressive co-stimulatory molecule, on the surface of mDCs from 5×FAD mice. Additionally, we found increases in interferon (IFN)-γ-producing CD4- or CD8- positive T cells in MLNs were increased in 5×FAD mice. Moreover, ex vivo treatment with Aβ peptides increased the production of IL-12 and IFN-γ by lymphocytes from 5×FAD mice.

CONCLUSION

The present study showed that pro-inflammatory mDC and T cells were induced in MLNs and PPs of 5×FAD mice.

Phase II Trial of Adjuvant Dendritic Cell Vaccine in Combination with Celecoxib, Interferon-α, and Rintatolimod in Patients Undergoing Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy for Peritoneal Metastases

BACKGROUND

Peritoneal metastases portend poor prognosis in the setting of standard chemotherapy. Cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (CRS/HIPEC) improves outcomes, but relapse is common. We report a phase II trial evaluating the safety and efficacy of adjuvant αDC1 vaccination with chemokine modulation (CKM) after CRS/HIPEC.

METHODS

Patients undergoing CRS/HIPEC for appendiceal cancer, colorectal cancer, or peritoneal mesothelioma were enrolled. In addition to standard adjuvant chemotherapy, patients received intranodal and intradermal injections of autologous tumor-loaded αDC1 vaccine. After each vaccine booster, patients received CKM over 4 days, consisting of celecoxib, interferon (IFN)-α, and rintatolimod.

RESULTS

Forty-six patients underwent CRS/HIPEC followed by αDC1 treatment, including 24 appendiceal primaries, 20 colorectal, and 2 mesotheliomas. DC maturation was successful, with 97% expressing HLA-DR and CD86. Tumor cell recovery from peritoneal tumors was challenging, resulting in only 17% of patients receiving the target dose of αDC1. The αDC1 and CKM regimen was well tolerated. CKM successfully modulated serum inflammatory cytokine and chemokine levels. Median progression-free survival (PFS) for appendiceal primaries was 50.4, 34.2, and 8.9 months for grade 1, 2, and 3 tumors, respectively, while median PFS for colorectal cancer was 20.5 and 8.9 months for moderately and poorly differentiated tumors, respectively.

CONCLUSIONS

Adjuvant autologous tumor antigen-loaded αDC1 vaccine and CKM is well tolerated. The mucinous nature of peritoneal metastases limits the feasibility of obtaining adequate autologous tumor cells. The improvement in median PFS did not meet our predefined thresholds, leading us to conclude that αDC1 vaccination is not appropriate for patients undergoing CRS/HIPEC for peritoneal metastases.

Current perspective on eicosanoids in asthma and allergic diseases: EAACI Task Force consensus report, part I

Eicosanoids are biologically active lipid mediators, comprising prostaglandins, leukotrienes, thromboxanes, and lipoxins, involved in several pathophysiological processes relevant to asthma, allergies, and allied diseases. Prostaglandins and leukotrienes are the most studied eicosanoids and established inducers of airway pathophysiology including bronchoconstriction and airway inflammation. Drugs inhibiting the synthesis of lipid mediators or their effects, such as leukotriene synthesis inhibitors, leukotriene receptors antagonists, and more recently prostaglandin D₂ receptor antagonists, have been shown to modulate features of asthma and allergic diseases. This review, produced by an European Academy of Allergy and Clinical Immunology (EAACI) task force, highlights our current understanding of eicosanoid biology and its role in mediating human pathology, with a focus on new findings relevant for clinical practice, development of novel therapeutics, and future research opportunities.

HBVsvp-Pulsed Dendritic Cell Immunotherapy Induces Th1 Polarization and Hepatitis B Virus-Specific Cytotoxic T Lymphocytes Production

Background

In chronic hepatitis B virus (CHB) patients, both dendritic cells (DCs) and T cells are functionally impaired and consequently the HBV-specific cellular immune responses are downregulated. The present study aims to investigate whether monocyte-derived DC (MoDCs)-pulsed-HBV subviral particles (HBVsvp) can polarize Th1 cells to induce HBV-specific cytotoxic T-lymphocytes (CTL) responses in CHB patients.

Methods and Materials

To this end, the human hepatoma HepG2.2.15 cell line was used to produce HBVsvp as a culturing system, and HBVsvp were concentrated for highly virus titer using the polyethylene glycol protocol. Peripheral blood mononuclear cells (PBMCs), collected from CHB patients and healthy donors, were differentiated into MoDCs and T cells. PBMCs-derived MoDCs were first pulsed with HBVsvp and then cultured with PBMCs-derived T cells. MoDCs and/or T subsets cells were identified for phenotypic activation by FACS analysis. The cytokine secretion of IL-4, IL-12, and IFN-γ in the culture supernatants was detected.

Results

The MoDCs were restored for their activation upon pulsing with HBVsvp in vitro, as identified by significantly overexpression of both CD86 and HLA-DR, and overproduction of IL-4 and IL-12. Furthermore, MoDCs-pulsed-HBVsvp induced Th1 frequencies and activated HBV-specific CTL to produce significantly highest amount of IFN-γ. Enhanced HBV-specific CTL led to strong cytolytic capacity against HepG2.2.15.

Conclusion

Overall, our data suggest that in vitro activation of MoDCs with HBVsvp overcomes the functionally impaired DCs and T cells in CHB patients offering a promising tool for therapeutic or vaccine-based approaches against HBV.

Cetuximab and IL-15 Promote NK and Dendritic Cell Activation In Vitro in Triple Negative Breast Cancer

Triple Negative Breast Cancer (TNBC) treatment is still challenging, and immunotherapy is a potential approach in this tumor subtype. Cetuximab is an IgG1 monoclonal antibody (mAb) directed against Epidermic Growth Factor Receptor (EGFR), a protein overexpressed in a subgroup of TNBC patients and associated with poor prognosis. Previously, we demonstrated in vitro that Cetuximab triggers Ab-dependent cell cytotoxicity against TNBC cells. In this study, using co-cultures including TNBC cells, and NK and Dendritic Cells (DCs) from healthy donors, we studied the effect of Cetuximab-activated NK cells on DC function. Given that we already demonstrated that TNBC has an immunosuppressive effect on NK cells, we also tested Cetuximab combination with IL-15. We determined that Cetuximab opsonization of TNBC cells increased IFN-γ and TNF-α production by NK cells co-cultured with DCs. Moreover, we showed that NK cells activated by TNBC cells opsonized with Cetuximab promoted tumor material uptake and maturation of DCs, as well as their ability to produce IL-12. Furthermore, the stimulation with IL-15 increased the activation of NK cells and the maturation of DCs. These results suggest that IL-15 may enhance the efficacy of Cetuximab in the treatment of TNBC by promoting activation of both NK cells and DCs.

Role of Dendritic Cells in Exposing Latent HIV-1 for the Kill

The development of effective yet nontoxic strategies to target the latent human immunodeficiency virus-1 (HIV-1) reservoir in antiretroviral therapy (ART)-suppressed individuals poses a critical barrier to a functional cure. The ‘kick and kill’ approach to HIV eradication entails proviral reactivation during ART, coupled with generation of cytotoxic T lymphocytes (CTLs) or other immune effectors equipped to eliminate exposed infected cells. Pharmacological latency reversal agents (LRAs) that have produced modest reductions in the latent reservoir ex vivo have not impacted levels of proviral DNA in HIV-infected individuals. An optimal cure strategy incorporates methods that facilitate sufficient antigen exposure on reactivated cells following the induction of proviral gene expression, as well as the elimination of infected targets by either polyfunctional HIV-specific CTLs or other immune-based strategies. Although conventional dendritic cells (DCs) have been used extensively for the purpose of inducing antigen-specific CTL responses in HIV-1 clinical trials, their immunotherapeutic potential as cellular LRAs has been largely ignored. In this review, we discuss the challenges associated with current HIV-1 eradication strategies, as well as the unharnessed potential of ex vivo-programmed DCs for both the ‘kick and kill’ of latent HIV-1.

Ex vivo dendritic cell generation-A critical comparison of current approaches

Dendritic cells (DCs) are professional antigen-presenting cells, required for the initiation of naïve and memory T cell responses and regulation of adaptive immunity. The discovery of DCs in 1973, which culminated in the Nobel Prize in Physiology or Medicine in 2011 for Ralph Steinman and colleagues, initially focused on the identification of adherent mononuclear cell fractions with uniquely stellate dendritic morphology, followed by key discoveries of their critical immunologic role in initiating and maintaining antigen-specific immunity and tolerance. The medical promise of marshaling these key capabilities of DCs for therapeutic modulation of antigen-specific immune responses has guided decades of research in hopes to achieve genuine physiologic partnership with the immune system. The potential uses of DCs in immunotherapeutic applications include cancer, infectious diseases, and autoimmune disorders; thus, methods for rapid and reliable large-scale production of DCs have been of great academic and clinical interest. However, difficulties in obtaining DCs from lymphoid and peripheral tissues, low numbers and poor survival in culture, have led to advancements in ex vivo production of DCs, both for probing molecular details of DC function as well as for experimenting with their clinical utility. Here, we review the development of a diverse array of DC production methodologies, ranging from cytokine-based strategies to genetic engineering tools devised for enhancing DC-specific immunologic functions. Further, we explore the current state of DC therapies in clinic, as well as emerging insights into physiologic production of DCs inspired by existing therapies.

Neuroendocrine Regulation of Tumor-Associated Immune Cells

Mounting preclinical and clinical evidence continues to support a role for the neuroendocrine system in the modulation of tumor biology and progression. Several studies have shown data supporting a link between chronic stress and cancer progression. Dysregulation of the sympathetic nervous system (SNS) and the hypothalamic-pituitary-adrenal (HPA) axis has been implicated in promoting angiogenesis, tumor cell proliferation and survival, alteration of the immune response and exacerbating inflammatory networks in the tumor microenvironment. Here, we review how SNS and HPA dysregulation contributes to disturbances in immune cell populations, modifies cancer biology, and impacts immunotherapy response. We also highlight several interventions aimed at circumventing the adverse effects stress has on cancer patients.

Phosphorothioated antisense oligodeoxynucleotide suppressing interleukin-10 is a safe and potent vaccine adjuvant

While vaccination is highly effective for the prevention of many infectious diseases, the number of adjuvants licensed for human use is currently very limited. The aim of this study was to evaluate the safety, efficacy, and to clarify the mechanism of a phosphorothioated interleukin (IL)-10-targeted antisense oligonucleotide (ASO) as an immune adjuvant in intradermal vaccination. The cytotoxicity of IL-10 ASO and its ability to promote T cell proliferation were assessed by Cell Counting Kit-8 (CCK-8) assay. The contents of IL-6, IL-8, TNF-α, IL-1β, and IL-10 in inoculated local tissue and the antigen-specific antibody titers in mouse serum samples were determined by ELISA. The target cells of IL-10 ASO were observed using immunofluorescent staining. The results showed that the specific antibody titer of ovalbumin (OVA), a model antigen, was increased 100-fold upon addition of IL-10 ASO as an adjuvant compared to that of OVA alone. IL-10 ASO showed an immunopotentiation efficacy similar to that of Freund's incomplete adjuvant, with no detectable cell or tissue toxicity. In vitro and in vivo experiments confirmed that IL-10 ASO enhances immune responses by temporarily suppressing IL-10 expression from local dendritic cells and consequently promoting T cell proliferation. In conclusion, IL-10 ASO significantly enhances immune responses against co-delivered vaccine antigens with high efficacy and low toxicity. It has the potential to be developed into a safe and efficient immune adjuvant.

A Characterization of Dendritic Cells and Their Role in Immunotherapy in Glioblastoma: From Preclinical Studies to Clinical Trials

Glioblastoma (GBM) is the most common and fatal primary central nervous system malignancy in adults with a median survival of less than 15 months. Surgery, radiation, and chemotherapy are the standard of care and provide modest benefits in survival, but tumor recurrence is inevitable. The poor prognosis of GBM has made the development of novel therapies targeting GBM of paramount importance. Immunotherapy via dendritic cells (DCs) has garnered attention and research as a potential strategy to boost anti-tumor immunity in recent years. As the “professional” antigen processing and presenting cells, DCs play a key role in the initiation of anti-tumor immune responses. Pre-clinical studies in GBM have shown long-term tumor survival and immunological memory in murine models with stimulation of DC activity with various antigens and costimulatory molecules. Phase I and II clinical trials of DC vaccines in GBM have demonstrated some efficacy in improving the median overall survival with minimal to no toxicity with promising initial results from the first Phase III trial. However, there remains no standardization of vaccines in terms of which antigens are used to pulse DCs ex vivo, sites of DC injection, and optimal adjuvant therapies. Future work with DC vaccines aims to elucidate the efficacy of DC-based therapy alone or in combination with other immunotherapy adjuvants in additional Phase III trials.

Overexpression of Dendritic Cell-Specific Intercellular Adhesion Molecule-3-Grabbing Nonintegrin in Dendritic Cells Protecting against Aspergillosis

Background:

Dendritic cells (DCs) play an important role in host defense against pathogen infection. DC-specific intercellular adhesion molecule-3-grabbing nonintegrin (SIGN) is a group II C-type lectin receptor and specifically expressed on the surface of DCs. This study aimed to determine whether DC-SIGN affects intracellular signaling activation, Th1/Th2 imbalance and aspergillus immune evasion in aspergillus infection, and explore the application of DC-SIGN-modified DCs in immunotherapy.

Methods:

DCs were first obtained from the mononuclear cells of peripheral blood. The interferon (IFN)-γ and dexamethasone (Dex) were used to stimulate DCs. The expression of DC-SIGN, Th1 and Th2 cytokines, and the capacity of DCs in stimulating T cells proliferation and phagocytosis, and nuclear factor (NF)-κB activation were analyzed. In addition, adenovirus expression vector Ad-DC-SIGN was generated to transfect DCs. Mannan was used to block DC-SIGN signaling for confirming the involvement of DC-SIGN function in Aspergillus fumigatus (Af)-induced DCs maturation. The unpaired, two-tailed Student's t-test was used in the comparisons between two groups.

Results:

Exogenous IFN-γ could activate Af-induced DCs and promote the Th0 cells toward Th1 profile (interleukin [IL]-12 in IFN-γ/Af group: 50.96 ± 4.38 pg/ml; control/Af group: 29.70 ± 2.00 pg/ml, t = 10.815, P < 0.001). On the other hand, Dex inhibited the secretion of Th2 cytokines (IL-10 in Dex/Af group: 5.27 ± 0.85 pg/ml; control/Af group: 15.14 ± 1.40 pg/ml, t = 14.761, P < 0.001)), and successfully caused immunosuppression. After transfection with Ad-DC-SIGN, DCs have improved phagocytosis (phagocytosis rates in Ad-DC-SIGN group: 74.0% ± 3.4%; control group: 64.7% ± 6.8%, t = 3.104, P = 0.013). There was more Th1 cytokine secreted in the Af-induced DC-SIGN modified DCs (IL-12 in Ad-DC-SIGN/Af group: 471.98 ± 166.31 pg/ml; control/Af group: 33.35 ± 5.98 pg/ml, t = 6.456, P = 0.001), correlated to the enhanced NF-κB activation.

Conclusion:

Overexpressing DC-SIGN in DCs had a protective function on aspergillosis.

Differences of the Structure of Immune Regulatory Cell Populations between Cellular Material from Sonographically Detected Focal Thyroid Lesions and Peripheral Blood in Humans

Focal thyroid lesions are common ultrasound findings with the estimated prevalence up to 67% of the population. They form characteristically enveloped regions with individual encapsulated microenvironment that may involve the specific distribution of immune system compounds—especially antigen presenting cells (APC). We analyzed and compared the most potent APC—plasmacytoid and conventional dendritic cells (DCs) subpopulations and three monocyte subpopulations as well as other immune cells—in peripheral blood and local blood of thyroid gland obtained parallelly in patients with focal thyroid lesions using flow cytometry. The analysis revealed significant differences in the distribution of main subsets of assessed cells between peripheral blood and biopsy material. The results support the existence of local, organ-specific immune reaction control networks within thyroid nodules.

Eicosanoid Control Over Antigen Presenting Cells in Asthma

Asthma is a common lung disease affecting 300 million people worldwide. Allergic asthma is recognized as a prototypical Th2 disorder, orchestrated by an aberrant adaptive CD4+ T helper (Th2/Th17) cell immune response against airborne allergens, that leads to eosinophilic inflammation, reversible bronchoconstriction, and mucus overproduction. Other forms of asthma are controlled by an eosinophil-rich innate ILC2 response driven by epithelial damage, whereas in some patients with more neutrophilia, the disease is driven by Th17 cells. Dendritic cells (DCs) and macrophages are crucial regulators of type 2 immunity in asthma. Numerous lipid mediators including the eicosanoids prostaglandins and leukotrienes influence key functions of these cells, leading to either pro- or anti-inflammatory effects on disease outcome. In this review, we will discuss how eicosanoids affect the functions of DCs and macrophages in the asthmatic lung and how this leads to aberrant T cell differentiation that causes disease.

Prostaglandins in asthma and allergic diseases

Prostaglandins are synthesized through the metabolism of arachidonic acid via the cyclooxygenase pathway. There are five primary prostaglandins, PGD₂, PGE₂, PGF₂, PGI₂, and thromboxane B₂, that all signal through distinct seven transmembrane, G-protein coupled receptors. The receptors through which the prostaglandins signal determines their immunologic or physiologic effects. For instance, the same prostaglandin may have opposing properties, dependent upon the signaling pathways activated. In this article, we will detail how inhibition of cyclooxygenase metabolism and regulation of prostaglandin signaling regulates allergic airway inflammation and asthma physiology. Possible prostaglandin therapeutic targets for allergic lung inflammation and asthma will also be reviewed, as informed by human studies, basic science, and animal models.

A novel potential effective strategy for enhancing the antitumor immune response in breast cancer patients using a viable cancer cell-dendritic cell-based vaccine

Dendritic cells (DCs) have been used in a number of clinical trials for cancer immunotherapy; however, they have achieved limited success in solid tumors. Consequently the aim of the present study was to identify a novel potential immunotherapeutic target for breast cancer patients through in vitro optimization of a viable DC-based vaccine. Immature DCs were primed by viable MCF-7 breast cancer cells and the activity and maturation of DCs were assessed through measuring CD83, CD86 and major histocompatibility complex (MHC)-II expression, in addition to different T cell subpopulations, namely CD4+ T cells, CD8+ T cells, and CD4+CD25+ forkhead box protein 3 (Foxp3)+ regulatory T cells (Tregs), by flow cytometric analysis. Foxp3 level was also measured by enzyme-linked immunosorbent assay (ELISA) in addition to reverse-transcription quantitative polymerase chain reaction. The levels of interleukin-12 (IL-12) and interferon-γ (IFN-γ) were determined by ELISA. Finally, the cytotoxicity of cytotoxic T lymphocytes (CTLs) was evaluated through measuring lactate dehydrogenase (LDH) release by ELISA. The results demonstrated that CD83+, CD86+ and MHC-II+ DCs were significantly elevated (P<0.001) following priming with breast cancer cells. In addition, there was increased activation of CD4+ and CD8+ T-cells, with a significant decrease of CD4+CD25+Foxp3+ Tregs (P<0.001). Furthermore, a significant downregulation of FOXP3 gene expression (P<0.001) was identified, and a significant decrease in the level of its protein following activation (P<0.001) was demonstrated by ELISA. Additionally, significant increases in the secretion of IL-12 and IFN-γ (P=0.001) were observed. LDH release was significantly increased (P<0.001), indicating a marked cytotoxicity of CTLs against cancer cells. Therefore viable breast cancer cell-DC-based vaccines could expose an innovative avenue for a novel breast cancer immunotherapy.

Ilixadencel - an Allogeneic Cell-Based Anticancer Immune Primer for Intratumoral Administration

Intratumoral administration of an immune primer is a therapeutic vaccine strategy aimed to trigger dendritic cell (DC)-mediated cross-presentation of cell-associated tumor antigens to cytotoxic CD8+ T cells without the need for tumor antigen characterization. The prevailing view is that these cross-presenting DCs have to be directly activated by pathogen-associated molecular patterns (PAMPS), including Toll-like receptor ligands or live microbial agents like oncolytic viruses. Emerging data are however challenging this view, indicating that the cross-presenting machinery in DCs is suboptimally activated by direct PAMP recognition, and that endogenous inflammatory factors are the main drivers of DC-mediated cross-presentation within the tumor. Here we present preclinical mode of action data, CMC and regulatory data, as well as initial clinical data on ilixadencel. This cell-based drug product is an off-the-shelf immune primer, consisting of pro-inflammatory allogeneic DCs secreting high amounts of pro-inflammatory chemokines and cytokines at the time of intratumoral administration. The mechanism of action of ilixadencel is to induce recruitment and activation of endogenous immune cells, including NK cells that subsequently promotes cross-presentation of cell-associated tumor antigens by co-recruited DCs.

Tumor lysate-loaded Bacterial Ghosts as a tool for optimized production of therapeutic dendritic cell-based cancer vaccines

Cancer immunotherapy with dendritic cell (DC)-based vaccines has been used to treat various malignancies for more than two decades, however generally showed a limited clinical success. Among various factors responsible for their modest clinical activity is the lack of universally applied, standardized protocols for the generation of clinical-grade DC vaccines, capable of inducing effective anti-tumor immune responses. We investigated Bacterial Ghosts (BGs) - empty envelopes of Gram-negative bacteria - as a tool for optimized production of DC vaccines. BGs possess various intact cell surface structures, exhibiting strong adjuvant properties required for the induction of DC maturation, whereas their empty internal space can be easily filled with a source tumor antigens, e.g. tumor lysate. Hence BGs emerge as an excellent platform for both the induction of immunogenic DC maturation and loading with tumor antigens in a single-step procedure. We compared the phenotype, cytokine secretion profile, functional activity and ability to induce immunogenic T-cell responses in vitro of human monocyte-derived DCs generated using BG platform and DCs matured with widely used lipopolysaccharide (LPS) plus interferon-γ cocktail and loaded with tumor lysate. Both approaches induced DC maturation, however BG-based protocol was superior to LPS-based protocol in terms of the ability to induce DCs with a lower tolerogenic potential, resulting in a more robust CD8⁺ T cell activation and their functional activity as well as significantly lower induction of regulatory T cells. These superior parameters are attributed, at least in part, to the ability of BG-matured DCs to resist potential immunosuppressive and pro-tolerogenic activity of various tumor cell lysates, including melanoma, renal carcinoma and glioblastoma.

Strategies to Genetically Modulate Dendritic Cells to Potentiate Anti-Tumor Responses in Hematologic Malignancies

Dendritic cell (DC) vaccination has been investigated as a potential strategy to target hematologic malignancies, while generating sustained immunological responses to control potential future relapse. Nonetheless, few clinical trials have shown robust long-term efficacy. It has been suggested that a combination of surmountable shortcomings, such as selection of utilized DC subsets, DC loading and maturation strategies, as well as tumor-induced immunosuppression may be targeted to maximize anti-tumor responses of DC vaccines. Generation of DC from CD34+ hematopoietic stem and progenitor cells (HSPCs) may provide potential in patients undergoing allogeneic HSPC transplantations for hematologic malignancies. CD34+ HSPC from the graft can be genetically modified to optimize antigen presentation and to provide sufficient T cell stimulatory signals. We here describe beneficial (gene)-modifications that can be implemented in various processes in T cell activation by DC, among which major histocompatibility complex (MHC) class I and MHC class II presentation, DC maturation and migration, cross-presentation, co-stimulation, and immunosuppression to improve anti-tumor responses.

The tolerogenic role of IFN-γ

Due to its extremely pleiotropic nature, the complex effects of IFN-γ exerted both on immune and non-immune cell types still remain only partially understood. The longstanding view of IFN-γ as being a predominantly inflammatory cytokine is constantly challenged by increasing demonstrations of its direct or indirect regulatory roles. Interferon-γ can exert tolerogenic effects on both innate and adaptive immune cell types, promoting tolerance of various antigen-presenting cells, and augmenting function and differentiation of regulatory T cells, respectively. Its capacity to induce IDO-competence is not limited to immune cells but extends to other cell types such as mesenchymal stem cells, epithelial cells, and tumors. The pro-inflammatory role of IFN-γ in tumor immune surveillance can backfire by directly inducing inhibitory molecule expression, such as PDL-1, on tumor cells. With increasing knowledge regarding the role of different helper T cell subsets in certain autoimmune diseases, the once contradictory observations of disease attenuation by IFN-γ can now be explained by its opposing interplay with other effector cytokines, particularly IL-17. The paradoxically immunosuppressive role of IFN-γ is also becoming evident in the transplantation setting, and graft-versus-host-disease. In the present review, we will discuss the latest findings that help to elucidate this dual role of IFN-γ at a cellular level, and in various pathophysiological states.

Innate Immunity against Cryptococcus, from Recognition to Elimination

Cryptococcus species, the etiological agents of cryptococcosis, are encapsulated fungal yeasts that predominantly cause disease in immunocompromised individuals, and are responsible for 15% of AIDS-related deaths worldwide. Exposure follows the inhalation of the yeast into the lung alveoli, making it incumbent upon the pattern recognition receptors (PRRs) of pulmonary phagocytes to recognize highly conserved pathogen-associated molecular patterns (PAMPS) of fungi. The main challenges impeding the ability of pulmonary phagocytes to effectively recognize Cryptococcus include the presence of the yeast's large polysaccharide capsule, as well as other cryptococcal virulence factors that mask fungal PAMPs and help Cryptococcus evade detection and subsequent activation of the immune system. This review will highlight key phagocyte cell populations and the arsenal of PRRs present on these cells, such as the Toll-like receptors (TLRs), C-type lectin receptors, NOD-like receptors (NLRs), and soluble receptors. Additionally, we will highlight critical cryptococcal PAMPs involved in the recognition of Cryptococcus. The question remains as to which PRR-ligand interaction is necessary for the recognition, phagocytosis, and subsequent killing of Cryptococcus.

Caveolin-mediated endocytosis of the Chlamydia M278 outer membrane peptide encapsulated in poly(lactic acid)-Poly(ethylene glycol) nanoparticles by mouse primary dendritic cells enhances specific immune effectors mediated by MHC class II and CD4+ T cells

We previously developed a Chlamydia trachomatis nanovaccine (PPM) by encapsulating a chlamydial M278 peptide within poly(lactic acid)-poly(ethylene glycol) biodegradable nanoparticles that immunopotentiated Chlamydia-specific immune effector responses in mice. Herein, we investigated the mechanistic interactions of PPM with mouse bone marrow-derived dendritic cells (DCs) for its uptake, trafficking, and T cell activation. Our results reveal that PPM triggered enhanced expression of effector cytokines and chemokines, surface activation markers (Cd1d2, Fcgr1), pathogen-sensing receptors (TLR2, Nod1), co-stimulatory (CD40, CD80, CD86) and MHC class I and II molecules. Co-culturing of PPM-primed DCs with T cells from C. muridarum vaccinated mice yielded an increase in Chlamydia-specific immune effector responses including CD3+ lymphoproliferation, CD3+CD4+ IFN-γ-secreting cells along with CD3+CD4+ memory (CD44high and CD62Lhigh) and effector (CD44high and CD62Llow) phenotypes. Intracellular trafficking analyses revealed an intense expression and colocalization of PPM predominantly in endosomes. PPM also upregulated the transcriptional and protein expression of the endocytic mediator, caveolin-1 in DCs. More importantly, the specific inhibition of caveolin-1 led to decreased expression of PPM-induced cytokines and co-stimulatory molecules. Our investigation shows that PPM provided enhancement of uptake, probably by exploiting the caveolin-mediated endocytosis pathway, endosomal processing, and MHC II presentation to immunopotentiate Chlamydia-specific immune effector responses mediated by CD4+ T cells.

Promoting the accumulation of tumor-specific T cells in tumor tissues by dendritic cell vaccines and chemokine-modulating agents

This protocol describes how to induce large numbers of tumor-specific cytotoxic T cells (CTLs) in the spleens and lymph nodes of mice receiving dendritic cell (DC) vaccines and how to modulate tumor microenvironments (TMEs) to ensure effective homing of the vaccination-induced CTLs to tumor tissues. We also describe how to evaluate the numbers of tumor-specific CTLs within tumors. The protocol contains detailed information describing how to generate a specialized DC vaccine with augmented ability to induce tumor-specific CTLs. We also describe methods to modulate the production of chemokines in the TME and show how to quantify tumor-specific CTLs in the lymphoid organs and tumor tissues of mice receiving different treatments. The combined experimental procedure, including tumor implantation, DC vaccine generation, chemokine-modulating (CKM) approaches, and the analyses of tumor-specific systemic and intratumoral immunity is performed over 30-40 d. The presented ELISpot-based ex vivo CTL assay takes 6 h to set up and 5 h to develop. In contrast to other methods of evaluating tumor-specific immunity in tumor tissues, our approach allows detection of intratumoral T-cell responses to nonmanipulated weakly immunogenic cancers. This detection method can be performed using basic laboratory skills, and facilitates the development and preclinical evaluation of new immunotherapies.

Recombinant rabies virus with the glycoprotein fused with a DC-binding peptide is an efficacious rabies vaccine

Our previous studies demonstrated that recruiting and/or activating dendritic cells (DCs) enhanced the immunogenicity of recombinant rabies viruses (rRABV). In this study, rRABV LBNSE with a small DC-binding peptide (designated as rLBNSE-DCBp) or a negative control peptide (designated as rLBNSE-DCCp) fused to the glycoprotein (G) was constructed and rescued. As expected, significantly more activated DCs were detected in rLBNSE-DCBp-immunized mice than those immunized with rLBNSE or rLBNSE-DCCp. Subsequently, significantly more generation of TFH and GC B cells were observed in rLBNSE-DCBp immunized mice than those in rLBNSE or rLBNSE-DCCp-immunized mice. In addition, significantly higher levels of virus neutralizing antibodies (VNAs) were observed in mice immunized with rLBNSE-DCBp than those immunized with rLBNSE or rLBNSE-DCCp, resulting in a better protection of rLBNSE-DCBp immunized mice against the lethal challenge. Taken together, our results suggest that rRABV with G fused with DCBp is a promising rabies vaccine candidate.

Adaptive Immunity to Cryptococcus neoformans Infections

The Cryptococcus neoformans/Cryptococcus gattii species complex is a group of fungal pathogens with different phenotypic and genotypic diversity that cause disease in immunocompromised patients as well as in healthy individuals. The immune response resulting from the interaction between Cryptococcus and the host immune system is a key determinant of the disease outcome. The species C. neoformans causes the majority of human infections, and therefore almost all immunological studies focused on C. neoformans infections. Thus, this review presents current understanding on the role of adaptive immunity during C. neoformans infections both in humans and in animal models of disease.

Amelioration of collagen-induced arthritis using antigen-loaded dendritic cells modified with NF-κB decoy oligodeoxynucleotides

Dendritic cells (DCs) play an important role in the initiation of autoimmunity in rheumatoid arthritis (RA); therefore, the use of DCs needs to be explored to develop new therapeutic approaches for RA. Here, we investigated the therapeutic effect of bovine type II collagen (BIIC)-loaded DCs modified with NF-κB decoy oligodeoxynucleotides (ODNs) on collagen-induced arthritis (CIA) in rats and explored the underlying mechanisms. DCs treated with BIIC and NF-κB decoy ODNs exhibited features of immature DCs with low levels of costimulatory molecule (CD80 and CD86) expression. The development of arthritis in rats with CIA injected with BIIC + NF-κB decoy ODN-propagated DCs (BIIC-decoy DCs) was significantly ameliorated compared to that in rats injected with BIIC-propagated DCs or phosphate-buffered saline. We also found that the BIIC-decoy DCs exerted antiarthritis effects by inhibiting self-lymphocyte proliferative response and suppressing IFN-γ and anti-BIIC antibody production and inducing IL-10 antibody production. Additionally, antihuman serum antibodies were successfully produced in the rats treated with BIIC-decoy DCs but not in those treated with NF-κB decoy ODN-propagated DCs; moreover, the BIIC-decoy DCs did not affect immune function in the normal rats. These findings suggested that NF-κB decoy ODN-modified DCs loaded with a specific antigen might offer a practical method for the treatment of human RA.

Cellular and molecular synergy in AS01-adjuvanted vaccines results in an early IFNγ response promoting vaccine immunogenicity

Combining immunostimulants in adjuvants can improve the quality of the immune response to vaccines. Here, we report a unique mechanism of molecular and cellular synergy between a TLR4 ligand, 3-O-desacyl-4’-monophosphoryl lipid A (MPL), and a saponin, QS-21, the constituents of the Adjuvant System AS01. AS01 is part of the malaria and herpes zoster vaccine candidates that have demonstrated efficacy in phase III studies. Hours after injection of AS01-adjuvanted vaccine, resident cells, such as NK cells and CD8⁺ T cells, release IFNγ in the lymph node draining the injection site. This effect results from MPL and QS-21 synergy and is controlled by macrophages, IL-12 and IL-18. Depletion strategies showed that this early IFNγ production was essential for the activation of dendritic cells and the development of Th1 immunity by AS01-adjuvanted vaccine. A similar activation was observed in the lymph node of AS01-injected macaques as well as in the blood of individuals receiving the malaria RTS,S vaccine. This mechanism, previously described for infections, illustrates how adjuvants trigger naturally occurring pathways to improve the efficacy of vaccines.

A mechanism is revealed by which vaccine components co-operate to stimulate the immune system and improve vaccine efficacy. Some vaccines are formulated with adjuvants—compounds that induce a greater immune response to the vaccine and help to elicit greater protection against future infections. Arnaud Didierlaurent and his team of researchers at GSK Vaccines, Belgium, demonstrate that the two immunostimulants in the adjuvant AS01, used in several recently developed vaccines, works in tandem to trigger the activation of important immune system moderators. The synergistic effect of the immunostimulants modulate specific immune cells at the site of the vaccination to better prepare the body against future infection. Studies such as this allow us to better understand how vaccines work and lay the foundation for more informed research into future vaccine development.

Chemokines and Their Receptors in Islet Allograft Rejection and as Targets for Tolerance Induction

Graft rejection is a major barrier to successful outcome of transplantation surgery. Islet transplantation introduces insulin secreting tissue into type 1 diabetes mellitus recipients, relieving patients from exogenous insulin injection. However, insulitis of grafted tissue and allograft rejection prevent long-term insulin independence. Leukocyte trafficking is necessary for the launch of successful immune responses to pathogen or allograft. Chemokines, small chemotactic cytokines, direct the migration of leukocytes through their interaction with chemokine receptors found on cell surfaces of immune cells. Unique receptor expression of leukocytes, and the specificity of chemokine secretion during various states of immune response, suggest that the extracellular chemokine milieu specifically homes certain leukocyte subsets. Thus, only those leukocytes required for the current immune task are attracted to the inflammatory site. Chemokine blockade, using antagonists and monoclonal antibodies directed against chemokine receptors, is an emerging and specific immunosuppressive strategy. Importantly, chemokine blockade may potentiate tolerance induction regimens to be used following transplantation surgery, and prevent the need for life-long immunosuppression of islet transplant recipients. Here, the role for chemokine blockade in islet transplant rejection and tolerance is reviewed.

Newcastle disease virus-like particles induce dendritic cell maturation and enhance viral-specific immune response

Circulating of genotype VII Newcastle disease virus (NDV) is a great threat to the poultry industry worldwide. Virus-like particles (VLPs) are increasingly being considered as potential viral vaccines due to their safety and efficacy. In this study, we analyzed in vitro the stimulatory effects of VLPs containing the matrix and hemagglutinin-neuraminidase of genotype VII NDV on dendritic cells (DCs) and evaluated their immunogenicity in mice. The results showed that immature bone marrow-derived dendritic cells (BMDCs) responded to stimulation with VLPs by up-regulating expressions of MHC II, CD40, CD80, and CD86 molecules and by increasing the cytokine secretions of TNF-α, IFN-γ, IL-6, and IL-12p70. Besides, VLPs enhanced the immunostimulatory capacity of DCs to stimulate autologous T cell proliferation. Furthermore, VLPs can induce efficient humoral and cellular immune responses, and recruit mature DCs to the spleen in C57BL/6 mice, as shown by an obvious increase in double-positive proliferation of splenic CD11c+CD86+ cells. These data indicate that NDV VLPs can be a valuable candidate for NDV vaccine development.

Nociceptin reduces the inflammatory immune microenvironment in a conventional murine model of airway hyperresponsiveness

BACKGROUND

Nociceptin/orphanin FQ (N/OFQ) and its receptor (NOP) are involved in airway hyperresponsiveness (AHR) and inflammation. However, the role of nociceptin at modulating the inflammatory immune microenvironment in asthma is still unclear.

OBJECTIVE

To understand the role of N/OFQ in the regulation of a Th2-like environment, we used a conventional murine model of AHR.

METHODS

Balb/c and CD1 mice were sensitized to ovalbumin (OVA) and treated with saline solution or N/OFQ, at days 0 and 7. A group of Balb/c mice were killed at 7 and 14 days from the first sensitization for the inflammatory profile evaluation while a group of Balb/c and CD1 mice were aerosol-challenged from day 21 to 23 with OVA and killed 24 h later for functional evaluations.

RESULTS

In OVA-sensitized mice, N/OFQ significantly reduced IL-4+ CD4+ T cells in lymph nodes (LN) and IL-13 in the lungs, while it induced IFN-γ increase in the lung. The efflux of dendritic cells (DCs) to the mediastinic LN and into the lung of OVA-sensitized mice was reduced in N/OFQ-treated and sensitized mice. N/OFQ reduced the expression of CD80 on DCs, indicating its ability to modulate the activation of DCs. In a less prone Th2-like environment mice strain, such as CD1 mice, N/OFQ did not modify lung resistances as observed in BALB/c mice. Finally, spectroscopic data showed the N/OFQ was able to interact onto the membrane of DCs obtained from Balb/c rather than CD1 mice, indicating its ability to modulate AHR in a Th2-like environment with a direct activity on DCs.

CONCLUSIONS AND CLINICAL RELEVANCE

Our data confirmed the capability of N/OFQ to modulate the immune microenvironment in the lung of Th2-biased, OVA-sensitized Balb/c mice, suggesting N/OFQ-NOP axis as a novel pharmacological tool to modulate the inflammatory immune microenvironment in asthma.

Preferentially expanding Vγ1+ γδ T cells are associated with protective immunity against Plasmodium infection in mice

γδ T cells play a crucial role in controlling malaria parasites. Dendritic cell (DC) activation via CD40 ligand (CD40L)-CD40 signaling by γδ T cells induces protective immunity against the blood-stage Plasmodium berghei XAT (PbXAT) parasites in mice. However, it is unknown which γδ T-cell subset has an effector role and is required to control the Plasmodium infection. Here, using antibodies to deplete TCR Vγ1⁺ cells, we saw that Vγ1⁺ γδ T cells were important for the control of PbXAT infection. Splenic Vγ1⁺ γδ T cells preferentially expand and express CD40L, and both Vγ1⁺ and Vγ4⁺ γδ T cells produce IFN-γ during infection. Although expression of CD40L on Vγ1⁺ γδ T cells is maintained during infection, the IFN-γ positivity of Vγ1⁺ γδ T cells is reduced in late-phase infection due to γδ T-cell dysfunction. In Plasmodium-infected IFN-γ signaling-deficient mice, DC activation is reduced, resulting in the suppression of γδ T-cell dysfunction and the dampening of γδ T-cell expansion in the late phase of infection. Our data suggest that Vγ1⁺ γδ T cells represent a major subset responding to PbXAT infection and that the Vγ1⁺ γδ T-cell response is dependent on IFN-γ-activated DCs.

Expression of CD14, IL10, and Tolerogenic Signature in Dendritic Cells Inversely Correlate with Clinical and Immunologic Response to TARP Vaccination in Prostate Cancer Patients

Purpose: Despite the vast number of clinical trials conducted so far, dendritic cell (DC)-based cancer vaccines have mostly shown unsatisfactory results. Factors and manufacturing procedures essential for these therapeutics to induce effective antitumor immune responses have yet to be fully characterized. We here aimed to identify DC markers correlating with clinical and immunologic response in a prostate carcinoma vaccination regimen.Experimental Design: We performed an extensive characterization of DCs used to vaccinate 18 patients with prostate carcinoma enrolled in a pilot trial of T-cell receptor gamma alternate reading frame protein (TARP) peptide vaccination (NCT00908258). Peptide-pulsed DC preparations (114) manufactured were analyzed by gene expression profiling, cell surface marker expression and cytokine release secretion, and correlated with clinical and immunologic responses.Results: DCs showing lower expression of tolerogenic gene signature induced strong antigen-specific immune response and slowing in PSA velocity, a surrogate for clinical response. These DCs were also characterized by lower surface expression of CD14, secretion of IL10 and MCP-1, and greater secretion of MDC. When combined, these four factors were able to remarkably discriminate DCs that were sufficiently potent to induce strong immunologic response.Conclusions: DC factors essential for the activation of immune responses associated with TARP vaccination in prostate cancer patients were identified. This study highlights the importance of in-depth characterization of DC vaccines and other cellular therapies, to understand the critical factors that hinder potency and potential efficacy in patients. Clin Cancer Res; 23(13); 3352-64. ©2017 AACR.

The histone demethylase inhibitor GSK-J4 limits inflammation through the induction of a tolerogenic phenotype on DCs

As it has been established that demethylation of lysine 27 of histone H3 by the lysine-specific demethylase JMJD3 increases immune responses and thus elicits inflammation, we hypothesize that inhibition of JMJD3 may attenuate autoimmune disorders. We found that in vivo administration of GSK-J4, a selective inhibitor of JMJD3 and UTX, ameliorates the severity of experimental autoimmune encephalomyelitis (EAE). In vitro experiments revealed that the anti-inflammatory effect of GSK-J4 was exerted through an effect on dendritic cells (DCs), promoting a tolerogenic profile characterized by reduced expression of costimulatory molecules CD80/CD86, an increased expression of tolerogenic molecules CD103 and TGF-β1, and reduced secretion of proinflammatory cytokines IL-6, IFN-γ, and TNF. Adoptive transfer of GSK-J4-treated DCs into EAE mice reduced the clinical manifestation of the disease and decreased the extent of inflammatory CD4+ T cells infiltrating the central nervous system. Notably, Treg generation, stability, and suppressive activity were all exacerbated by GSK-J4-treated DCs without affecting Th1 and Th17 cell production. Our data show that GSK-J4-mediated modulation of inflammation is achieved by a direct effect on DCs and that systemic treatment with GSK-J4 or adoptive transfer of GSK-J4-treated DCs ex vivo may be promising approaches for the treatment of inflammatory and autoimmune disorders.

Impairment of dendritic cell functions in patients with adaptor protein-3 complex deficiency

Hermansky-Pudlak syndrome type 2 (HPS2) is a primary immunodeficiency due to adaptor protein-3 (AP-3) complex deficiency. HPS2 patients present neutropenia, partial albinism, and impaired lysosomal vesicles formation in hematopoietic cells. Given the role of dendritic cells (DCs) in the immune response, we studied monocyte-derived DCs (moDCs) and plasmacytoid DCs (pDCs) in two HPS2 siblings. Mature HPS2 moDCs showed impaired expression of CD83 and DC-lysosome-associated membrane protein (LAMP), low levels of MIP1-β/CCL4, MIG/CXCL9, and severe defect of interleukin-12 (IL-12) secretion. DCs in lymph-node biopsies from the same patients showed a diffuse cytoplasm reactivity in a large fraction of DC-LAMP(+) cells, instead of the classical dot-like stain. In addition, analysis of pDC-related functions of blood-circulating mononuclear cells revealed reduced interferon-α secretion in response to herpes simplex virus-1 (HSV-1), whereas granzyme-B induction upon IL-3/IL-10 stimulation was normal. Finally, T-cell costimulatory activity, as measured by mixed lymphocyte reaction assay, was lower in patients, suggesting that function and maturation of DCs is abnormal in patients with HPS2.

Dendritic Cells Pulsed with Peptides of GP63 Induce Differential Protection against Experimental Cutaneous Leishmaniasis

The need for a vaccine against Leishmania spp., a major cause of worldwide morbidity and mortality, is urgent. We tested the efficacy of an experimental vaccination in murine models of cutaneous leishmaniasis, using dendritic cells (DCs) pulsed with synthetic or native parasite antigens. DCs pulsed with peptide 154–169aa of gp63 or soluble promastigote lysate (SPL) triggered antigen-specific immune responses and efficiently reduced lesion formation and parasite load of genetically susceptible BALB/c mice infected with Leishmania major. This effect was accompanied by a modulation of the cellular immune response towards a Th1 profile. Vaccination of genetically resistant CBA mice with DCs pulsed with peptide 154–169aa or SPL did not affect the course of the disease, whereas pulsing with the epitope 467–482aa of gp63 resulted in disease exacerbation, accompanied by a switch to a Th2 profile. In view of our continuously growing knowledge about the immunobiology of DCs, these findings suggest that vaccination with DCs pulsed with defined peptides could be a strategy against infectious diseases. Peptide selection is a prerequisite as they can differentially regulate the type of immune response in susceptible or resistant hosts.

Dendritic Cell-Like Cells Accumulate in Regenerating Murine Skeletal Muscle after Injury and Boost Adaptive Immune Responses Only upon a Microbial Challenge

Skeletal muscle injury causes a local sterile inflammatory response. In parallel, a state of immunosuppression develops distal to the site of tissue damage. Granulocytes and monocytes that are rapidly recruited to the site of injury contribute to tissue regeneration. In this study we used a mouse model of traumatic skeletal muscle injury to investigate the previously unknown role of dendritic cells (DCs) that accumulate in injured tissue. We injected the model antigen ovalbumin (OVA) into the skeletal muscle of injured or sham-treated mice to address the ability of these DCs in antigen uptake, migration, and specific T cell activation in the draining popliteal lymph node (pLN). Immature DC-like cells appeared in the skeletal muscle by 4 days after injury and subsequently acquired a mature phenotype, as indicated by increased expression of the costimulatory molecules CD40 and CD86. After the injection of OVA into the muscle, OVA-loaded DCs migrated into the pLN. The migration of DC-like cells from the injured muscle was enhanced in the presence of the microbial stimulus lipopolysaccharide at the site of antigen uptake and triggered an increased OVA-specific T helper cell type 1 (Th1) response in the pLN. Naïve OVA-loaded DCs were superior in Th1-like priming in the pLN when adoptively transferred into the skeletal muscle of injured mice, a finding indicating the relevance of the microenvironment in the regenerating skeletal muscle for increased Th1-like priming. These findings suggest that DC-like cells that accumulate in the regenerating muscle initiate a protective immune response upon microbial challenge and thereby overcome injury-induced immunosuppression.

DC generation from peripheral blood mononuclear cells in patients with chronic myeloid leukemia: Influence of interferons on DC yield and functional properties

In Chronic Myeloid Leukemia (CML), standard treatment consists of modern tyrosine-kinase inhibitors (TKI). Nevertheless, there is evidence that immune responses against leukemia-associated antigens (LAA) may play an important role in disease control. Dendritic cell (DC)- based immunotherapy is able to induce T cell responses against LAA and might therefore pose an interesting therapeutic option in CML, especially in the setting of minimal residual disease (MRD). GMP production of DC for clinical vaccination remains a time- and cost- intensive procedure and standardized DC generation is warranted. We asked whether maturation-induction with IFN-γ and IFN-α has an influence on functional properties of DC derived from peripheral blood mononuclear cells (PBMC) in CML patients. Monocyte-derived DC from healthy donors and from patients with CML were analyzed after maturation-induction with our TNF-α-containing standard cytokine cocktail with or without addition of IFN-α and/or IFN-γ. Our results confirm that the addition of IFN-γ leads to enhanced IL-12 secretion in healthy donors. In contrast, in CML patients, IFN-γ was not able to increase IL-12 secretion, possibly due to a higher degree of cell adherence and lower cell yield during the cell culture. Our data suggest, that- in contrast to healthy donors-, additional interferons are not beneficial for maturation induction during large-scale DC production in patients with CML.

Linked in: immunologic membrane nanotube networks

Membrane nanotubes, also termed tunneling nanotubes, are F-actin-based structures that can form direct cytoplasmic connections and support rapid communication between distant cells. These nanoscale conduits have been observed in diverse cell types, including immune, neuronal, stromal, cancer, and stem cells. Until recently, little was known about the mechanisms involved in membrane nanotube development in myeloid origin APCs or how membrane nanotube networks support their ability to bridge innate and adaptive immunity. New research has provided insight into the modes of induction and regulation of the immune process of "reticulation" or the development of multicellular membrane nanotube networks in dendritic cells. Preprogramming by acute type 1 inflammatory mediators at their immature stage licenses mature type 1-polarized dendritic cells to reticulate upon subsequent interaction with CD40 ligand-expressing CD4(+) Th cells. Dendritic cell reticulation can support direct antigen transfer for amplification of specific T cell responses and can be positively or negatively regulated by signals from distinct Th cell subsets. Membrane nanotubes not only enhance the ability of immature dendritic cells to sense pathogens and rapidly mobilize nearby antigen-presenting cells in the peripheral tissues but also likely support communication of pathogen-related information from mature migratory dendritic cells to resident dendritic cells in lymph nodes. Therefore, the reticulation process facilitates a coordinated multicellular response for the efficient initiation of cell-mediated adaptive immune responses. Herein, we discuss studies focused on the molecular mechanisms of membrane nanotube formation, structure, and function in the context of immunity and how pathogens, such as HIV-1, may use dendritic cell reticulation to circumvent host defenses.

Pathogen-Associated Molecular Patterns Induced Crosstalk between Dendritic Cells, T Helper Cells, and Natural Killer Helper Cells Can Improve Dendritic Cell Vaccination

A coordinated cellular interplay is of crucial importance in both host defense against pathogens and malignantly transformed cells. The various interactions of Dendritic Cells (DC), Natural Killer (NK) cells, and T helper (Th) cells can be influenced by a variety of pathogen-associated molecular patterns (PAMPs) and will lead to enhanced CD8⁺ effector T cell responses. Specific Pattern Recognition Receptor (PRR) triggering during maturation enables DC to enhance Th1 as well as NK helper cell responses. This effect is correlated with the amount of IL-12p70 released by DC. Activated NK cells are able to amplify the proinflammatory cytokine profile of DC via the release of IFN-γ. The knowledge on how PAMP recognition can modulate the DC is of importance for the design and definition of appropriate therapeutic cancer vaccines. In this review we will discuss the potential role of specific PAMP-matured DC in optimizing therapeutic DC-based vaccines, as some of these DC are efficiently activating Th1, NK cells, and cytotoxic T cells. Moreover, to optimize these vaccines, also the inhibitory effects of tumor-derived suppressive factors, for example, on the NK-DC crosstalk, should be taken into account. Finally, the suppressive role of the tumor microenvironment in vaccination efficacy and some proposals to overcome this by using combination therapies will be described.