The Basis of Oncoimmunology.

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.

Molecular signatures of antibody responses derived from a systems biology study of five human vaccines.

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.

Functional specializations of human epidermal Langerhans cells and CD14+ dermal dendritic cells.

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.

A modular analysis framework for blood genomics studies: application to systemic lupus erythematosus.

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.

Human CD141+ dendritic cells induce CD4+ T cells to produce type 2 cytokines.

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.

Dendritic cells as therapeutic vaccines against cancer.

Mouse studies have shown that the immune system can reject tumours, and the identification of tumour antigens that can be recognized by human T cells has facilitated the development of immunotherapy protocols. Vaccines against cancer aim to induce tumour-specific effector T cells that can reduce the tumour mass, as well as tumour-specific memory T cells that can control tumour relapse. Owing to their capacity to regulate T-cell immunity, dendritic cells are increasingly used as adjuvants for vaccination, and the immunogenicity of antigens delivered by dendritic cells has now been shown in patients with cancer. A better understanding of how dendritic cells regulate immune responses will allow us to better exploit these cells to induce effective antitumour immunity.

Breast cancer instructs dendritic cells to prime interleukin 13-secreting CD4+ T cells that facilitate tumor development.

We previously reported (Bell, D., P. Chomarat, D. Broyles, G. Netto, G.M. Harb, S. Lebecque, J. Valladeau, J. Davoust, K.A. Palucka, and J. Banchereau. 1999. J. Exp. Med. 190: 1417-1426) that breast cancer tumors are infiltrated with mature dendritic cells (DCs), which cluster with CD4(+) T cells. We now show that CD4(+) T cells infiltrating breast cancer tumors secrete type 1 (interferon gamma) as well as high levels of type 2 (interleukin [IL] 4 and IL-13) cytokines. Immunofluorescence staining of tissue sections revealed intense IL-13 staining on breast cancer cells. The expression of phosphorylated signal transducer and activator of transcription 6 in breast cancer cells suggests that IL-13 actually delivers signals to cancer cells. To determine the link between breast cancer, DCs, and CD4(+) T cells, we implanted human breast cancer cell lines in nonobese diabetic/LtSz-scid/scid beta2 microglobulin-deficient mice engrafted with human CD34(+) hematopoietic progenitor cells and autologous T cells. There, CD4(+) T cells promote early tumor development. This is dependent on DCs and can be partially prevented by administration of IL-13 antagonists. Thus, breast cancer targets DCs to facilitate its development.

Cross-priming CD8+ T cells by targeting antigens to human dendritic cells through DCIR.

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.

How the study of children with rheumatic diseases identified interferon-alpha and interleukin-1 as novel therapeutic targets.

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.

Humanized mice: are we there yet?

Animal models have been instrumental in increasing the understanding of human physiology, particularly immunity. However, these animal models have been limited by practical considerations and genetic diversity. The creation of humanized mice that carry partial or complete human physiological systems may help overcome these obstacles. The National Institute of Allergy and Infectious Diseases convened a workshop on humanized mouse models for immunity in Bethesda, MD, on June 13-14, 2005, during which researchers discussed the benefits and limitations of existing animal models and offered insights into the development of future humanized mouse models.

Influenza virus and poly(I:C) inhibit MHC class I-restricted presentation of cell-associated antigens derived from infected dead cells captured by human dendritic cells.

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.

CD2 distinguishes two subsets of human plasmacytoid dendritic cells with distinct phenotype and functions.

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 and cytokines in human inflammatory and autoimmune diseases.

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.

Expansion of melanoma-specific cytolytic CD8+ T cell precursors in patients with metastatic melanoma vaccinated with CD34+ progenitor-derived dendritic cells.

Cancer vaccines aim at inducing (a) tumor-specific effector T cells able to reduce/eliminate the tumor mass, and (b) long-lasting tumor-specific memory T cells able to control tumor relapse. We have shown earlier, in 18 human histocompatibility leukocyte antigen (HLA)-A*0201 patients with metastatic melanoma, that vaccination with peptide-loaded CD34-dendritic cells (DCs) leads to expansion of melanoma-specific interferon gamma-producing CD8+ T cells in the blood. Here, we show in 9 out of 12 analyzed patients the expansion of cytolytic CD8+ T cell precursors specific for melanoma differentiation antigens. These precursors yield, upon single restimulation with melanoma peptide-pulsed DCs, cytotoxic T lymphocytes (CTLs) able to kill melanoma cells. Melanoma-specific CTLs can be grown in vitro and can be detected in three assays: (a) melanoma tetramer binding, (b) killing of melanoma peptide-pulsed T2 cells, and (c) killing of HLA-A*0201 melanoma cells. The cytolytic activity of expanded CTLs correlates with the frequency of melanoma tetramer binding CD8+ T cells. Thus, CD34-DC vaccines can expand melanoma-specific CTL precursors that can kill melanoma antigen-expressing targets. These results justify the design of larger follow-up studies to assess the immunological and clinical response to peptide-pulsed CD34-DC vaccines.

Interferon and granulopoiesis signatures in systemic lupus erythematosus blood.

Systemic lupus erythematosus (SLE) is a prototype systemic autoimmune disease characterized by flares of high morbidity. Using oligonucleotide microarrays, we now show that active SLE can be distinguished by a remarkably homogeneous gene expression pattern with overexpression of granulopoiesis-related and interferon (IFN)-induced genes. Using the most stringent statistical analysis (Bonferroni correction), 15 genes were found highly up-regulated in SLE patients, 14 of which are targets of IFN and one, defensin DEFA-3, a major product of immature granulocytes. A more liberal correction (Benjamini and Hochberg correction) yielded 18 additional genes, 12 of which are IFN-regulated and 4 granulocyte-specific. Indeed immature neutrophils were identified in a large fraction of SLE patients white blood cells. High dose glucocorticoids, a standard treatment of disease flares, shuts down the interferon signature, further supporting the role of this cytokine in SLE. The expression of 10 genes correlated with disease activity according to the SLEDAI. The most striking correlation (P < 0.001, r = 0.55) was found with the formyl peptide receptor-like 1 protein that mediates chemotactic activities of defensins. Therefore, while the IFN signature confirms the central role of this cytokine in SLE, microarray analysis of blood cells reveals that immature granulocytes may be involved in SLE pathogenesis.

Dendritic cells and humoral immunity in humans.

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.

Longitudinal tracking of human dendritic cells in murine models using magnetic resonance imaging.

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.

Broad influenza-specific CD8+ T-cell responses in humanized mice vaccinated with influenza virus vaccines.

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.

Circulating tumor antigen-specific regulatory T cells in patients with metastatic melanoma.

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.

Tumour immunity: effector response to tumour and role of the microenvironment.

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.