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Inflammation affects tumor immune surveillance and resistance to therapy. Here, we show that production of IL1β in primary breast cancer tumors is linked with advanced disease and originates from tumor-infiltrating CD11c + myeloid cells. IL1β production is triggered by cancer cell membrane-derived TGFβ. Neutralizing TGFβ or IL1 receptor prevents breast cancer progression in humanized mouse model. Patients with metastatic HER2 - breast cancer display a transcriptional signature of inflammation in the blood leukocytes, which is attenuated after IL1 blockade. When present in primary breast cancer tumors, this signature discriminates patients with poor clinical outcomes in two independent public datasets (TCGA and METABRIC). Significance: IL1β orchestrates tumor-promoting inflammation in breast cancer and can be targeted in patients using an IL1 receptor antagonist. Cancer Res; 78(18); 5243-58. ©2018 AACR See related commentary by Dinarello, p. 5200 ., (©2018 American Association for Cancer Research.)

Aging is linked to deficiencies in immune responses and increased systemic inflammation. To unravel the regulatory programs behind these changes, we applied systems immunology approaches and profiled chromatin accessibility and the transcriptome in PBMCs and purified monocytes, B cells, and T cells. Analysis of samples from 77 young and elderly donors revealed a novel and robust aging signature in PBMCs, with simultaneous systematic chromatin closing at promoters and enhancers associated with T cell signaling and a potentially stochastic chromatin opening mostly found at quiescent and repressed sites. Combined analyses of chromatin accessibility and the transcriptome uncovered immune molecules activated/inactivated with aging and identified the silencing of the IL7R gene and the IL-7 signaling pathway genes as potential biomarkers. This signature is borne by memory CD8 + T cells, which exhibited an aging-related loss in binding of NF-κB and STAT factors. Thus, our study provides a unique and comprehensive approach to identifying candidate biomarkers and provides mechanistic insights into aging-associated immunodeficiency., (© 2017 Ucar et al.)

Dendritic cells (DCs) are critical for the launching of protective T cell immunity in response to viral infection. Viruses can directly infect DCs, thereby compromising their viability and suppressing their ability to activate immune responses. How DC function is maintained in light of this paradox is not understood. By analyzing the susceptibility of primary human DC subsets to viral infections, we report that CD141 + DCs have an innate resistance to infection by a broad range of enveloped viruses, including HIV and influenza virus. In contrast, CD1c + DCs are susceptible to infection, which enables viral antigen production but impairs their immune functions and survival. The ability of CD141 + DCs to resist infection is conferred by RAB15, a vesicle-trafficking protein constitutively expressed in this DC subset. We show that CD141 + DCs rely on viral antigens produced in bystander cells to launch cross-presentation-driven T cell responses. By dissociating viral infection from antigen presentation, this mechanism protects the functional capacity of DCs to launch adaptive immunity against viral infection., (Copyright © 2017 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.)

The targeting of vaccine antigens to antigen presenting cells (APC), such as dendritic cells (DCs), is a promising strategy for boosting vaccine immunogenicity and, in turn, protective and/or therapeutic efficacy. However, in vivo systems are needed to evaluate the potential of this approach for testing human vaccines. To this end, we examined human CD8(+) T-cell expansion to novel DC-targeting vaccines in vitro and in vivo in humanized mice. Vaccines incorporating the influenza matrix protein-1 (FluM1) antigen fused to human specific antibodies targeting different DC receptors, including DEC-205, DCIR, Dectin-1, and CD40, elicited human CD8(+) T-cell responses, as defined by the magnitude of specific CD8(+) T-cells to the targeted antigen. In vitro we observed differences in response to the different vaccines, particularly between the weakly immunogenic DEC-205-targeted and more strongly immunogenic CD40-targeted vaccines, consistent with previous studies. However, in humanized mice adoptively transferred (AT) with mature human T cells (HM-T), vaccines that performed weakly in vitro (i.e., DEC-205, DCIR, and Dectin-1) gave stronger responses in vivo, some resembling those of the strongly immunogenic CD40-targeted vaccine. These results demonstrate the utility of the humanized mouse model as a platform for studies of human vaccines., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

The immune mechanism leading to the generation of protective antibody responses following influenza trivalent inactivated vaccine (TIV) vaccinations remains largely uncharacterized. We recently reported that TIV vaccination induced a transient increase of circulating ICOS(+)PD-1(+)CXCR3(+) T follicular helper (cTfh) cells in blood, which positively correlated with the induction of protective antibody responses measured at day 28. However, whether and how these T cells directly contribute to antibody response remains unclear. In this study, we analyzed the changes after TIV vaccination in the amount and the avidity of the polyclonal antibodies specific for the HA1 subunit of the pandemic H1N1 virus, and analyzed the correlation with the increase of ICOS(+)PD-1(+)CXCR3(+) cTfh cells. We found that both the amount and the avidity of specific antibodies rapidly increased during the first 7 days after TIV. Importantly, the increase of ICOS(+)PD-1(+)CXCR3(+) cTfh cells strongly correlated with the increase in the avidity of antibodies, particularly in subjects who did not have high affinity antibodies at baseline. We propose that ICOS(+)PD-1(+)CXCR3(+) Tfh cells directly contribute to the generation of high-avidity antibodies after TIV vaccinations by selectively interacting with high affinity B cells at extrafollicular sites.

Large numbers of melanoma lesions develop resistance to targeted inhibition of mutant BRAF or fail to respond to checkpoint blockade. We explored whether modulation of intratumoral antigen-presenting cells (APCs) could increase responses to these therapies. Using mouse melanoma models, we found that CD103(+) dendritic cells (DCs) were the only APCs transporting intact antigens to the lymph nodes and priming tumor-specific CD8(+) T cells. CD103(+) DCs were required to promote anti-tumoral effects upon blockade of the checkpoint ligand PD-L1; however, PD-L1 inhibition only led to partial responses. Systemic administration of the growth factor FLT3L followed by intratumoral poly I:C injections expanded and activated CD103(+) DC progenitors in the tumor, enhancing responses to BRAF and PD-L1 blockade and protecting mice from tumor rechallenge. Thus, the paucity of activated CD103(+) DCs in tumors limits checkpoint-blockade efficacy and combined FLT3L and poly I:C therapy can enhance tumor responses to checkpoint and BRAF blockade., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Cancer vaccine development has been vigorously pursued for 40 years. Immunity to tumor antigens can be elicited by most vaccines tested, but their clinical efficacy remains modest. We argue that a concerted international effort is necessary to understand the human antitumor immune response and achieve clinically effective cancer vaccines., (Copyright © 2016, American Association for the Advancement of Science.)

Cancer heterogeneity, a hallmark enabling clonal survival and therapy resistance, is shaped by active immune responses. Antigen-specific T cells can control cancer, as revealed clinically by immunotherapeutics such as adoptive T-cell transfer and checkpoint blockade. The host immune system is thus a powerful tool that, if better harnessed, could significantly enhance the efficacy of cytotoxic therapy and improve outcomes for cancer sufferers. To realize this vision, however, a number of research frontiers must be tackled. These include developing strategies for neutralizing tumor-promoting inflammation, broadening T-cell repertoires (via vaccination), and elucidating the mechanisms by which immune cells organize tumor microenvironments to regulate T-cell activity. Such efforts will pave the way for identifying new targets for combination therapies that overcome resistance to current treatments and promote long-term cancer control., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Background: Mantle cell lymphoma (MCL) is a distinct clinical pathologic subtype of B cell non-Hodgkin's lymphoma often associated with poor prognosis. New therapeutic approaches based on boosting anti-tumor immunity are needed. MCL is associated with overexpression of cyclin D1 thus rendering this molecule an interesting target for immunotherapy., Methods: We show here a novel strategy for the development of recombinant vaccines carrying cyclin D1 cancer antigens that can be targeted to dendritic cells (DCs) via CD40., Results: Healthy individuals and MCL patients have a broad repertoire of cyclin D1-specific CD4(+) and CD8(+) T cells. Cyclin D1-specific T cells secrete IFN-γ. DCs loaded with whole tumor cells or with selected peptides can elicit cyclin D1-specific CD8(+) T cells that kill MCL tumor cells. We developed a recombinant vaccine based on targeting cyclin D1 antigen to human DCs via an anti-CD40 mAb. Targeting monocyte-derived human DCs in vitro with anti-CD40-cyclin D1 fusion protein expanded a broad repertoire of cyclin D1-specific CD4(+) and CD8(+) T cells., Conclusions: This study demonstrated that cyclin D1 represents a good target for immunotherapy and targeting cyclin D1 to DCs provides a new strategy for mantle cell lymphoma vaccine.

Whereas preclinical investigations and clinical studies have established that CD8 + T cells can profoundly affect cancer progression, the underlying mechanisms are still elusive. Challenging the prevalent view that the beneficial effect of CD8 + T cells in cancer is solely attributable to their cytotoxic activity, several reports have indicated that the ability of CD8 + T cells to promote tumor regression is dependent on their cytokine secretion profile and their ability to self-renew. Evidence has also shown that the tumor microenvironment can disarm CD8 + T cell immunity, leading to the emergence of dysfunctional CD8 + T cells. The existence of different types of CD8 + T cells in cancer calls for a more precise definition of the CD8 + T cell immune phenotypes in cancer and the abandonment of the generic terms "pro-tumor" and "antitumor." Based on recent studies investigating the functions of CD8 + T cells in cancer, we here propose some guidelines to precisely define the functional states of CD8 + T cells in cancer.

During the past decades, anticancer immunotherapy has evolved from a promising therapeutic option to a robust clinical reality. Many immunotherapeutic regimens are now approved by the US Food and Drug Administration and the European Medicines Agency for use in cancer patients, and many others are being investigated as standalone therapeutic interventions or combined with conventional treatments in clinical studies. Immunotherapies may be subdivided into "passive" and "active" based on their ability to engage the host immune system against cancer. Since the anticancer activity of most passive immunotherapeutics (including tumor-targeting monoclonal antibodies) also relies on the host immune system, this classification does not properly reflect the complexity of the drug-host-tumor interaction. Alternatively, anticancer immunotherapeutics can be classified according to their antigen specificity. While some immunotherapies specifically target one (or a few) defined tumor-associated antigen(s), others operate in a relatively non-specific manner and boost natural or therapy-elicited anticancer immune responses of unknown and often broad specificity. Here, we propose a critical, integrated classification of anticancer immunotherapies and discuss the clinical relevance of these approaches.

Dendritic cells (DCs) play the central role in the priming of naive T cells and the differentiation of unique effector T cells. In this study, using lung tissues and blood from both humans and humanized mice, we analyzed the response of human CD1c(+) and CD141(+) DC subsets to live-attenuated influenza virus. Specifically, we analyzed the type of CD4(+) T cell immunity elicited by live-attenuated influenza virus-exposed DCs. Both DC subsets induce proliferation of allogeneic naive CD4(+) T cells with the capacity to secrete IFN-γ. However, CD141(+) DCs are uniquely able to induce the differentiation of IL-4- and IL-13-producing CD4(+) T cells. CD141(+) DCs induce IL-4- and IL-13-secreting CD4(+) T cells through OX40 ligand. Thus, CD141(+) DCs demonstrate remarkable plasticity in guiding adaptive immune responses., (Copyright © 2014 by The American Association of Immunologists, Inc.)

Blood monocytes from children with systemic lupus erythematosus (SLE) behave similar to dendritic cells (DCs), and SLE serum induces healthy monocytes to differentiate into DCs in a type I IFN-dependent manner. In this study, we found that these monocytes display significant transcriptional changes, including a prominent IFN signature, compared with healthy controls. Few of those changes, however, explain DC function. Exposure to allogeneic T cells in vitro reprograms SLE monocytes to acquire DC phenotype and function, and this correlates with both IFN-inducible (IP10) and proinflammatory cytokine (IL-1β and IL6) expression. Furthermore, we found that both IFN and SLE serum induce the upregulation of CCR7 transcription in these cells. CCR7 protein expression, however, requires a second signal provided by TLR agonists such as LPS. Thus, SLE serum "primes" a subset of monocytes to readily (<24 h) respond to TLR agonists and acquire migratory DC properties. Our findings might explain how microbial infections exacerbate lupus., (Copyright © 2014 by The American Association of Immunologists, Inc.)

Mice repopulated with human hematopoietic cells are a powerful tool for the study of human hematopoiesis and immune function in vivo. However, existing humanized mouse models cannot support development of human innate immune cells, including myeloid cells and natural killer (NK) cells. Here we describe two mouse strains called MITRG and MISTRG, in which human versions of four genes encoding cytokines important for innate immune cell development are knocked into their respective mouse loci. The human cytokines support the development and function of monocytes, macrophages and NK cells derived from human fetal liver or adult CD34(+) progenitor cells injected into the mice. Human macrophages infiltrated a human tumor xenograft in MITRG and MISTRG mice in a manner resembling that observed in tumors obtained from human patients. This humanized mouse model may be used to model the human immune system in scenarios of health and pathology, and may enable evaluation of therapeutic candidates in an in vivo setting relevant to human physiology.

Many vaccines induce protective immunity via antibodies. Systems biology approaches have been used to determine signatures that can be used to predict vaccine-induced immunity in humans, but whether there is a 'universal signature' that can be used to predict antibody responses to any vaccine is unknown. Here we did systems analyses of immune responses to the polysaccharide and conjugate vaccines against meningococcus in healthy adults, in the broader context of published studies of vaccines against yellow fever virus and influenza virus. To achieve this, we did a large-scale network integration of publicly available human blood transcriptomes and systems-scale databases in specific biological contexts and deduced a set of transcription modules in blood. Those modules revealed distinct transcriptional signatures of antibody responses to different classes of vaccines, which provided key insights into primary viral, protein recall and anti-polysaccharide responses. Our results elucidate the early transcriptional programs that orchestrate vaccine immunity in humans and demonstrate the power of integrative network modeling.

Seasonal influenza vaccine protects 60 to 90% of healthy young adults from influenza infection. The immunological events that lead to the induction of protective antibody responses remain poorly understood in humans. We identified the type of CD4+ T cells associated with protective antibody responses after seasonal influenza vaccinations. The administration of trivalent split-virus influenza vaccines induced a temporary increase of CD4+ T cells expressing ICOS, which peaked at day 7, as did plasmablasts. The induction of ICOS was largely restricted to CD4+ T cells coexpressing the chemokine receptors CXCR3 and CXCR5, a subpopulation of circulating memory T follicular helper cells. Up to 60% of these ICOS+CXCR3+CXCR5+CD4+ T cells were specific for influenza antigens and expressed interleukin-2 (IL-2), IL-10, IL-21, and interferon-γ upon antigen stimulation. The increase of ICOS+CXCR3+CXCR5+CD4+ T cells in blood correlated with the increase of preexisting antibody titers, but not with the induction of primary antibody responses. Consistently, purified ICOS+CXCR3+CXCR5+CD4+ T cells efficiently induced memory B cells, but not naïve B cells, to differentiate into plasma cells that produce influenza-specific antibodies ex vivo. Thus, the emergence of blood ICOS+CXCR3+CXCR5+CD4+ T cells correlates with the development of protective antibody responses generated by memory B cells upon seasonal influenza vaccination.

There have been substantial advances in cancer diagnostics and therapies in the past decade. Besides chemotherapeutic agents and radiation therapy, approaches now include targeting cancer cell-intrinsic mediators linked to genetic aberrations in cancer cells, in addition to cancer cell-extrinsic pathways, especially those regulating vascular programming of solid tumors. More recently, immunotherapeutics have entered the clinic largely on the basis of the recognition that several immune cell subsets, when chronically activated, foster tumor development. Here, we discuss clinical and experimental studies delineating protumorigenic roles for immune cell subsets that are players in cancer-associated inflammation. Some of these cells can be targeted to reprogram their function, leading to resolution, or at least neutralization, of cancer-promoting chronic inflammation, thereby facilitating cancer rejection.

Dendritic cells (DCs) can initiate and shape host immune responses toward either immunity or tolerance by their effects on antigen-specific CD4(+) T cells. DC-asialoglycoprotein receptor (DC-ASGPR), a lectinlike receptor, is a known scavenger receptor. Here, we report that targeting antigens to human DCs via DC-ASGPR, but not lectin-like oxidized-LDL receptor, Dectin-1, or DC-specific ICAM-3-grabbing nonintegrin favors the generation of antigen-specific suppressive CD4(+) T cells that produce interleukin 10 (IL-10). These findings apply to both self- and foreign antigens, as well as memory and naive CD4(+) T cells. The generation of such IL-10-producing CD4(+) T cells requires p38/extracellular signal-regulated kinase phosphorylation and IL-10 induction in DCs. We further demonstrate that immunization of nonhuman primates with antigens fused to anti-DC-ASGPR monoclonal antibody generates antigen-specific CD4(+) T cells that produce IL-10 in vivo. This study provides a new strategy for the establishment of antigen-specific IL-10-producing suppressive T cells in vivo by targeting whole protein antigens to DCs via DC-ASGPR.

Purpose: To facilitate development of innovative immunotherapy approaches, especially for treatment concepts exploiting the potential benefits of personalized therapy, there is a need to develop and validate tools to identify patients who can benefit from immunotherapy. Despite substantial effort, we do not yet know which parameters of antitumor immunity to measure and which assays are optimal for those measurements., Experimental Design: The iSBTc-SITC (International Society for Biological Therapy of Cancer-Society for Immunotherapy of Cancer), FDA (Food and Drug Administration), and NCI (National Cancer Institute) partnered to address these issues for immunotherapy of cancer. Here, we review the major challenges, give examples of approaches and solutions, and present our recommendations., Results and Conclusions: Although specific immune parameters and assays are not yet validated, we recommend following standardized (accurate, precise, and reproducible) protocols and use of functional assays for the primary immunologic readouts of a trial; consideration of central laboratories for immune monitoring of large, multi-institutional trials; and standardized testing of several phenotypic and functional potential potency assays specific to any cellular product. When reporting results, the full QA (quality assessment)/QC (quality control) should be conducted and selected examples of truly representative raw data and assay performance characteristics should be included. Finally, to promote broader analysis of multiple aspects of immunity, and gather data on variability, we recommend that in addition to cells and serum, RNA and DNA samples be banked (under standardized conditions) for later testing. We also recommend that sufficient blood be drawn to allow for planned testing of the primary hypothesis being addressed in the trial, and that additional baseline and posttreatment blood is banked for testing novel hypotheses (or generating new hypotheses) that arise in the field., (©2011 AACR.)

The human breast tumor microenvironment can display features of T helper type 2 (Th2) inflammation, and Th2 inflammation can promote tumor development. However, the molecular and cellular mechanisms contributing to Th2 inflammation in breast tumors remain unclear. Here, we show that human breast cancer cells produce thymic stromal lymphopoietin (TSLP). Breast tumor supernatants, in a TSLP-dependent manner, induce expression of OX40L on dendritic cells (DCs). OX40L(+) DCs are found in primary breast tumor infiltrates. OX40L(+) DCs drive development of inflammatory Th2 cells producing interleukin-13 and tumor necrosis factor in vitro. Antibodies neutralizing TSLP or OX40L inhibit breast tumor growth and interleukin-13 production in a xenograft model. Thus, breast cancer cell-derived TSLP contributes to the inflammatory Th2 microenvironment conducive to breast tumor development by inducing OX40L expression on DCs.

In the search for a therapeutic HIV-1 vaccine, we describe herein the development of a monocyte-derived dendritic cell (DC) vaccine loaded with a mixture of HIV-1-antigen lipopeptides (ANRS HIV-LIPO-5 Vaccine). LIPO-5 is comprised of five HIV-1-antigen peptides (Gag(17-35), Gag(253-284), Nef(66-97), Nef(116-145), and Pol(325-355)), each covalently linked to a palmitoyl-lysylamide moiety. Monocytes enriched from HIV-1-infected highly active antiretroviral therapy (HAART)-treated patients were cultured for three days with granulocyte-macrophage colony-stimulating factor and alpha-interferon. At day 2, the DCs were loaded with ANRS HIV-LIPO-5 vaccine, activated with lipopolysaccharide, harvested at day 3 and frozen. Flow cytometry analysis of thawed DC vaccines showed expression of DC differentiation markers: CD1b/c, CD14, HLA-DR, CD11c, co-stimulatory molecule CD80 and DC maturation marker CD83. DCs were capable of eliciting an HIV-1-antigen-specific response, as measured by expansion of autologous CD4(+) and CD8(+) T-cells. The expanded T-cells secreted gamma-IFN and interleukin (IL)-13, but not IL-10. The safety and immunogenicity of this DC vaccine are being evaluated in a Phase I/II clinical trial in chronically HIV-1-infected patients on HAART (clinicaltrials.gov identifier: NCT00796770)., (Copyright © 2010. Published by Elsevier B.V.)

Ex vivo generated dendritic cells are currently used to induce therapeutic immunity in solid tumors. Effective immune response requires dendritic cells to home and remain in lymphoid organs to allow for adequate interaction with T lymphocytes. The aim of the current study was to detect and track Feridex labeled human dendritic cells in murine models using magnetic resonance imaging. Human dendritic cells were incubated with Feridex and the effect of labeling on dendritic cells immune function was evaluated. Ex vivo dendritic cell phantoms were used to estimate sensitivity of the magnetic resonance methods and in vivo homing was evaluated after intravenous or subcutaneous injection. R2*-maps of liver, spleen, and draining lymph nodes were obtained and inductively coupled plasma mass spectrometry or relaxometry methods were used to quantify the Feridex tissue concentrations. Correlations between in vivo R2* values and iron content were then determined. Feridex labeling did not affect dendritic cell maturation or function. Phantom results indicated that it was possible to detect 125 dendritic cells within a given slice. Strong correlation between in vivo R2* values and iron deposition was observed. Importantly, Feridex-labeled dendritic cells were detected in the spleen for up to 2 weeks postintravenous injection. This study suggests that magnetic resonance imaging may be used to longitudinally track Feridex-labeled human dendritic cells for up to 2 weeks after injection., (Copyright © 2010 Wiley-Liss, Inc.)

Dectin-1, a C-type lectin recognizing fungal and mycobacterial pathogens, can deliver intracellular signals that activate dendritic cells (DCs), resulting in initiation of immune responses and expansion of Th17 CD4(+) T cell responses. In this paper, we studied the roles of human Dectin-1 (hDectin-1) expressed on DCs in the induction and activation of Ag-specific CD8(+) T cell responses. We first generated an agonistic anti-hDectin-1 mAb, which recognizes the hDectin-1 Glu(143)-Ile(162) region. It bound to in vitro monocyte-derived DCs and to in vivo CD1c(+)CD1a(+) dermal DCs but not to epidermal Langerhans cells. Anti-hDectin-1-mediated DC activation resulted in upregulation of costimulatory molecules and secretion of multiple cytokines and chemokines in a Syk-dependent manner. DCs activated with the anti-hDectin-1 mAb could significantly enhance both neo and foreign Ag-specific CD8(+) T cell responses by promoting both the expansion of CD8(+) T cells and their functional activities. We further demonstrated that delivering Ags to DCs via hDectin-1 using anti-hDectin-1-Ag conjugates resulted in potent Ag-specific CD8(+) T cell responses. Thus, hDectin-1 expressed on DCs can contribute to the induction and activation of cellular immunity against intracellular pathogens, such as mycobacteria, that are recognized by DCs via Dectin-1. Vaccines based on delivering Ags to DCs with an agonistic anti-hDectin-1 mAb could elicit CD8(+) T cell-mediated immunity.

We evaluated human CD8(+) T-cell responses generated by targeting antigens to dendritic cells (DCs) through various lectin receptors. We found the immunoreceptor tyrosine-based inhibitory motif-containing DC immunoreceptor (DCIR) to mediate potent cross-presentation. A single exposure to a low dose of anti-DCIR-antigen conjugate initiated antigen-specific CD8(+) T-cell immunity by all human DC subsets including ex vivo-generated DCs, skin-isolated Langerhans cells, and blood myeloid DCs and plasmacytoid DCs. The delivery of influenza matrix protein (FluMP) through DCIR resulted in expansion of FluMP-specific memory CD8(+) T cells. Enhanced specific CD8(+) T-cell responses were observed when an antigen was delivered to the DCs via DCIR, compared with those induced by a free antigen, or antigen conjugated to a control monoclonal antibody or delivered via DC-SIGN, another lectin receptor. DCIR targeting also induced primary CD8(+) T-cell responses against self (MART-1) and viral (HIV gag) antigens. Addition of Toll-like receptor (TLR) 7/8 agonist enhanced DCIR-mediated cross-presentation as well as cross-priming, particularly when combined with a CD40 signal. TLR7/8 activation was associated with increased expansion of the primed CD8(+) T cells, high production of interferon-γ and tumor necrosis factor-α, and reduced levels of type 2-associated cytokines. Thus, antigen targeting via the human DCIR receptor allows activation of specific CD8(+) T-cell immunity.

Dendritic cells (DCs) orchestrate the innate and adaptive immune systems to induce tolerance and immunity. DC plasticity and subsets are prominent determinants in the regulation of immune responses. Our recent studies suggest that humoral and cellular immunity is regulated by different myeloid DC subsets with distinct intrinsic properties in humans. Although antibody response is preferentially mediated by CD14(+) dermal DCs, cytotoxic T-cell response is preferentially mediated by Langerhans cells (LCs). Thus, mechanisms whereby DCs induce humoral and cellular immunity seem to be fundamentally distinct. In this review, we will focus on the role of DCs in the development of humoral immunity. We will also discuss the mechanisms whereby DCs induce CD4(+) T cells associated with aiding B-cell response, including T follicular helper (Tfh) cells, and why human LCs lack this ability.

Plasmacytoid dendritic cells (pDCs) are key regulators of antiviral immunity. They rapidly secrete IFN-alpha and cross-present viral Ags, thereby launching adaptive immunity. In this study, we show that activated human pDCs inhibit replication of cancer cells and kill them in a contact-dependent fashion. Expression of CD2 distinguishes two pDC subsets with distinct phenotype and function. Both subsets secrete IFN-alpha and express granzyme B and TRAIL. CD2(high) pDCs uniquely express lysozyme and can be found in tonsils and in tumors. Both subsets launch recall T cell responses. However, CD2(high) pDCs secrete higher levels of IL12p40, express higher levels of costimulatory molecule CD80, and are more efficient in triggering proliferation of naive allogeneic T cells. Thus, human blood pDCs are composed of subsets with specific phenotype and functions.

Dendritic cells (DCs) orchestrate a repertoire of immune responses that endows resistance to infection and tolerance to self. Understanding the principles by which DCs control immunity and tolerance has provided a rich basis for studying and improving clinical outcome of human disease treatment. Several features contribute to the complexity of the DC system. Among these, plasticity and existence of subsets are prominent determinants to the quality of the elicited immune responses. Indeed, different DC subsets are distributed in peripheral tissues and the blood and display different microbial receptors, surface molecules and cytokine expression, all of which influence the immunologic outcome. The biologic raison d'être for separate DC subsets has been the focus of many studies including our own and is being reviewed with an emphasis on human skin DCs.

During viral infection, dendritic cells (DCs) capture infected cells and present viral Ags to CD8(+) T cells. However, activated DCs might potentially present cell-associated Ags derived from captured dead cells. In this study, we find that human DCs that captured dead cells containing the TLR3 agonist poly(I:C) produced cytokines and underwent maturation, but failed to elicit autologous CD8(+) T cell responses against Ags of dead cells. Accordingly, DCs that captured dead cells containing poly(I:C), or influenza virus, are unable to activate CD8(+) T cell clones specific to cell-associated Ags of captured dead cells. CD4(+) T cells are expanded with DCs that have captured poly(I:C)-containing dead cells, indicating the inhibition is specific for MHC class I-restricted cross-presentation. Furthermore, these DCs can expand naive allogeneic CD8(+) T cells. Finally, soluble or targeted Ag is presented when coloaded onto DCs that have captured poly(I:C)-containing dead cells, indicating the inhibition is specific for dead cell cargo that is accompanied by viral or poly(I:C) stimulus. Thus, DCs have a mechanism that prevents MHC class I-restricted cross-presentation of cell-associated Ag when they have captured dead infected cells.

The development of novel human vaccines would be greatly facilitated by the development of in vivo models that permit preclinical analysis of human immune responses. Here, we show that nonobese diabetic severe combined immunodeficiency (NOD/SCID) beta(2) microglobulin(-/-) mice, engrafted with human CD34+ hematopoietic progenitors and further reconstituted with T cells, can mount specific immune responses against influenza virus vaccines. Live attenuated trivalent influenza virus vaccine induces expansion of CD8+ T cells specific to influenza matrix protein (FluM1) and nonstructural protein 1 in blood, spleen, and lungs. On ex vivo exposure to influenza antigens, antigen-specific CD8+ T cells produce IFN-gamma and express cell-surface CD107a. FluM1-specific CD8+ T cells can be also expanded in mice vaccinated with inactivated trivalent influenza virus vaccine. Expansion of antigen-specific CD8+ T cells is dependent on reconstitution of the human myeloid compartment. Thus, this humanized mouse model permits preclinical testing of vaccines designed to induce cellular immunity, including those against influenza virus. Furthermore, this work sets the stage for systematic analysis of the in vivo functions of human DCs. This, in turn, will allow a new approach to the rational design and preclinical testing of vaccines that cannot be tested in human volunteers.

Cancer immunotherapy seeks to mobilize a patient's immune system for therapeutic benefit. It can be passive, that is, transfer of immune effector cells (T cells) or proteins (antibodies), or active, that is, vaccination. Early clinical trials testing vaccination with ex vivo generated dendritic cells (DCs) pulsed with tumor antigens provide a proof-of-principle that therapeutic immunity can be elicited. Yet, the clinical benefit measured by regression of established tumors in patients with stage IV cancer has been observed in a fraction of patients only. The next generation of DC vaccines is expected to generate large numbers of high avidity effector CD8 T cells and to overcome regulatory T cells and suppressive environment established by tumors, a major obstacle in metastatic disease. Therapeutic vaccination protocols will combine improved DC vaccines with chemotherapy to exploit immunogenic chemotherapy regimens. We foresee adjuvant vaccination in patients with resected tumors but at high risk of relapse to be based on in vivo targeting of DCs with fusion proteins containing anti-DCs antibodies, antigens from tumor stem/propagating cells, and DC activators.

Little is known about the functional differences between the human skin myeloid dendritic cell (DC) subsets, epidermal CD207(+) Langerhans cells (LCs) and dermal CD14(+) DCs. We showed that CD14(+) DCs primed CD4(+) T cells into cells that induce naive B cells to switch isotype and become plasma cells. In contrast, LCs preferentially induced the differentiation of CD4(+) T cells secreting T helper 2 (Th2) cell cytokines and were efficient at priming and crosspriming naive CD8(+) T cells. A third DC population, CD14(-)CD207(-)CD1a(+) DC, which resides in the dermis, could activate CD8(+) T cells better than CD14(+) DCs but less efficiently than LCs. Thus, the human skin displays three DC subsets, two of which, i.e., CD14(+) DCs and LCs, display functional specializations, the preferential activation of humoral and cellular immunity, respectively.

The analysis of patient blood transcriptional profiles offers a means to investigate the immunological mechanisms relevant to human diseases on a genome-wide scale. In addition, such studies provide a basis for the discovery of clinically relevant biomarker signatures. We designed a strategy for microarray analysis that is based on the identification of transcriptional modules formed by genes coordinately expressed in multiple disease data sets. Mapping changes in gene expression at the module level generated disease-specific transcriptional fingerprints that provide a stable framework for the visualization and functional interpretation of microarray data. These transcriptional modules were used as a basis for the selection of biomarkers and the development of a multivariate transcriptional indicator of disease progression in patients with systemic lupus erythematosus. Thus, this work describes the implementation and application of a methodology designed to support systems-scale analysis of the human immune system in translational research settings.

Summary: Our studies in children with rheumatic diseases have led to the identification of two of the oldest cytokines, type I interferon (IFN) and interleukin 1 (IL-1), as important pathogenic players in systemic lupus erythematosus (SLE) and systemic onset juvenile arthritis (SoJIA), respectively. These findings were obtained by studying the transcriptional profiles of patient blood cells and by assessing the biological and transcriptional effect(s) of active patient sera on healthy blood cells. We also identified a signature that can be used to promptly diagnose SoJIA from other febrile conditions. Finally, our pilot clinical trials using IL-1 blockers have shown remarkable clinical benefits in SoJIA patients refractory to other medications.

Substantial evidence shows that inflammation promotes oncogenesis and, occasionally, participates in cancer rejection. This paradox can be accounted for by a dynamic switch from chronic smouldering inflammation promoting cancer-cell survival to florid, tissue-disruptive inflammatory reactions that trigger cancer-cell destruction. Clinical and experimental observations suggest that the mechanism of this switch recapitulates the events associated with pathogen infection, which stimulate immune cells to recognise danger signals and activate immune effector functions. Generally, cancers do not have danger signals and, therefore, they cannot elicit strong immune reactions. Synthetic molecules have been developed that mimic pathogen invasion at the tumour site. These compounds activate dendritic cells to produce proinflammatory cytokines, which in turn trigger cytotoxic mechanisms leading to cancer death. Simultaneously, dendritic cells capture antigen shed by dying cancer cells, undergo activation, and stimulate antigen-specific T and B cells. This process results in massive amplification of the antineoplastic inflammatory process. Thus, although anti-inflammatory drugs can prevent onset of some malignant diseases, induction of T cells specific for tumour antigen by active immunisation, combined with powerful activation signals within the cancer microenvironment, might yield the best strategy for treatment of established cancers.

Dendritic cells (DCs) produce cytokines and are susceptible to cytokine-mediated activation. Thus, interaction of resting immature DCs with TLR ligands, for example nucleic acids, or with microbes leads to a cascade of pro-inflammatory cytokines and skewing of T cell responses. Conversely, several cytokines are able to trigger DC activation (maturation) via autocrine, for example TNF and plasmacytoid DCs, and paracrine, for example type I IFN and myeloid DCs, pathways. By controlling DC activation, cytokines regulate immune homeostasis and the balance between tolerance and immunity. The increased production and/or bioavailability of cytokines and associated alterations in DC homeostasis have been implicated in various human inflammatory and autoimmune diseases. Targeting these cytokines with biological agents as already is the case with TNF and IL-1 represents a success of immunology and the coming years will expand the range of cytokines as therapeutic targets in autoinflammatory and autoimmune pathology.

Dendritic cells (DCs) are antigen-presenting cells specialized to initiate and maintain immunity and tolerance. DCs initiate immune responses in a manner that depends on signals they receive from pathogens, surrounding cells and their products. Most tumors are infiltrated by DCs. Thus, interactions between DCs and dying tumor cells may determine the balance between immunity and tolerance to tumor cells. In addition, DCs also display non-immunologic effects on tumors and the tumor microenvironment. Therefore, improved understanding of the cross talk between tumor cells and DCs may suggest new approaches to improve cancer therapy.

Although it is accepted that regulatory T cells (T regs) contribute to cancer progression, most studies in the field consider nonantigen-specific suppression. Here, we show the presence of tumor antigen-specific CD4(+) T regs in the blood of patients with metastatic melanoma. These CD4(+) T regs recognize a broad range of tumor antigens, including gp100 and TRP1 (melanoma tissue differentiation antigens), NY-ESO-1 (cancer/testis antigen) and survivin (inhibitor of apoptosis protein (IAP) family antigen). These tumor antigen-specific T regs proliferate in peripheral blood mononuclear cells (PBMC) cultures in response to specific 15-mer peptides, produce preferentially IL-10 and express high levels of FoxP3. They suppress autologous CD4(+)CD25(-) T cell responses in a cell contact-dependent manner and thus share properties of both naturally occurring regulatory T cells and type 1 regulatory T cells. Such tumor antigen-specific T regs were not detected in healthy individuals. These tumor antigen-specific T regs might thus represent another target for immunotherapy of metastatic melanoma.

Immunotherapy seeks to mobilize a patient's immune system for therapeutic benefit. It can be passive, i.e. transfer of immune effector cells (T cells) or proteins (antibodies), or active, i.e. vaccination. In cancer, passive immunotherapy can lead to some objective clinical responses, thus demonstrating that the immune system can reject tumors. However, passive immunotherapy is not expected to yield long-lived memory T cells that might control tumor outgrowth. Active immunotherapy with dendritic cell (DC)-based vaccines has the potential to induce both tumor-specific effector and memory T cells. Early clinical trials testing vaccination with ex vivo-generated DCs pulsed with tumor antigens provide a proof-of-principle that therapeutic immunity can be elicited. Yet, there is a need to improve their efficacy. The next generation of DC vaccines is expected to generate large numbers of high-avidity effector CD8(+) T cells and to overcome regulatory T cells. Therapeutic vaccination protocols will combine improved ex vivo DC vaccines with therapies that offset the suppressive environment established by tumors.

The dendritic cell (DC) system of antigen-presenting cells controls immunity and tolerance. DCs initiate and regulate immune responses in a manner that depends on signals they receive from microbes and their cellular environment. They allow the immune system to make qualitatively distinct responses against different microbial infections. DCs are composed of subsets that express different microbial receptors and express different surface molecules and cytokines. Our studies lead us to propose that interstitial (dermal) DCs preferentially activate humoral immunity, whereas Langerhans cells preferentially induce cellular immunity. Alterations of the DC system result in diseases such as autoimmunity, allergy, and cancer. Conversely, DCs can be exploited for vaccination, and novel vaccines that directly target DCs in vivo are being designed.