Metabolic Phenotypes of Response to Vaccination in Humans
2017; 169 (5): 862-?
Herpes zoster (shingles) causes significant morbidity in immune compromised hosts and older adults. Whereas a vaccine is available for prevention of shingles, its efficacy declines with age. To help to understand the mechanisms driving vaccinal responses, we constructed a multiscale, multifactorial response network (MMRN) of immunity in healthy young and older adults immunized with the live attenuated shingles vaccine Zostavax. Vaccination induces robust antigen-specific antibody, plasmablasts, and CD4+ T cells yet limited CD8+ T cell and antiviral responses. The MMRN reveals striking associations between orthogonal datasets, such as transcriptomic and metabolomics signatures, cell populations, and cytokine levels, and identifies immune and metabolic correlates of vaccine immunity. Networks associated with inositol phosphate, glycerophospholipids, and sterol metabolism are tightly coupled with immunity. Critically, the sterol regulatory binding protein 1 and its targets are key integrators of antibody and T follicular cell responses. Our approach is broadly applicable to study human immunity and can help to identify predictors of efficacy as well as mechanisms controlling immunity to vaccination.
View details for DOI 10.1016/j.cell.2017.04.026
View details for Web of Science ID 000401515900012
View details for PubMedID 28502771
View details for PubMedCentralID PMC5711477
Systems analysis of protective immune responses to RTS, S malaria vaccination in humans
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
2017; 114 (9): 2425-2430
RTS,S is an advanced malaria vaccine candidate and confers significant protection against Plasmodium falciparum infection in humans. Little is known about the molecular mechanisms driving vaccine immunity. Here, we applied a systems biology approach to study immune responses in subjects receiving three consecutive immunizations with RTS,S (RRR), or in those receiving two immunizations of RTS,S/AS01 following a primary immunization with adenovirus 35 (Ad35) (ARR) vector expressing circumsporozoite protein. Subsequent controlled human malaria challenge (CHMI) of the vaccinees with Plasmodium-infected mosquitoes, 3 wk after the final immunization, resulted in ∼50% protection in both groups of vaccinees. Circumsporozoite protein (CSP)-specific antibody titers, prechallenge, were associated with protection in the RRR group. In contrast, ARR-induced lower antibody responses, and protection was associated with polyfunctional CD4+ T-cell responses 2 wk after priming with Ad35. Molecular signatures of B and plasma cells detected in PBMCs were highly correlated with antibody titers prechallenge and protection in the RRR cohort. In contrast, early signatures of innate immunity and dendritic cell activation were highly associated with protection in the ARR cohort. For both vaccine regimens, natural killer (NK) cell signatures negatively correlated with and predicted protection. These results suggest that protective immunity against P. falciparum can be achieved via multiple mechanisms and highlight the utility of systems approaches in defining molecular correlates of protection to vaccination.
View details for DOI 10.1073/pnas.1621489114
View details for Web of Science ID 000395101200083
View details for PubMedID 28193898
View details for PubMedCentralID PMC5338562
Adjuvanting a Simian Immunodeficiency Virus Vaccine with Toll-Like Receptor Ligands Encapsulated in Nanoparticles Induces Persistent Antibody Responses and Enhanced Protection in TRIM5 alpha Restrictive Macaques
JOURNAL OF VIROLOGY
2017; 91 (4)
Our previous work has shown that antigens adjuvanted with ligands specific for Toll-like receptor 4 (TLR4) and TLR7/8 encapsulated in poly(lactic-co-glycolic) acid (PLGA)-based nanoparticles (NPs) induce robust and durable immune responses in mice and macaques. We investigated the efficacy of these NP adjuvants in inducing protective immunity against simian immunodeficiency virus (SIV). Rhesus macaques (RMs) were immunized with NPs containing TLR4 and TLR7/8 agonists mixed with soluble recombinant SIVmac239-derived envelope (Env) gp140 and Gag p55 (protein) or with virus-like particles (VLPs) containing SIVmac239 Env and Gag. NP-adjuvanted vaccines induced robust innate responses, antigen-specific antibody responses of a greater magnitude and persistence, and enhanced plasmablast responses compared to those achieved with alum-adjuvanted vaccines. NP-adjuvanted vaccines induced antigen-specific, long-lived plasma cells (LLPCs), which persisted in the bone marrow for several months after vaccination. NP-adjuvanted vaccines induced immune responses that were associated with enhanced protection against repeated low-dose, intravaginal challenges with heterologous SIVsmE660 in animals that carried TRIM5α restrictive alleles. The protection induced by immunization with protein-NP correlated with the prechallenge titers of Env-specific IgG antibodies in serum and vaginal secretions. However, no such correlate was apparent for immunization with VLP-NP or alum as the adjuvant. Transcriptional profiling of peripheral blood mononuclear cells isolated within the first few hours to days after primary vaccination revealed that NP-adjuvanted vaccines induced a molecular signature similar to that induced by the live attenuated yellow fever viral vaccine. This systems approach identified early blood transcriptional signatures that correlate with Env-specific antibody responses in vaginal secretions and protection against infection. These results demonstrate the adjuvanticity of the NP adjuvant in inducing persistent and protective antibody responses against SIV in RMs with implications for the design of vaccines against human immunodeficiency virus (HIV).The results of the RV144 HIV vaccine trial, which demonstrated a rapid waning of protective immunity with time, have underscored the need to develop strategies to enhance the durability of protective immune responses. Our recent work in mice has highlighted the capacity of nanoparticle-encapsulated TLR ligands (NP) to induce potent and durable antibody responses that last a lifetime in mice. In the present study, we evaluated the ability of these NP adjuvants to promote robust and durable protective immune responses against SIV in nonhuman primates. Our results demonstrate that immunization of rhesus macaques with NP adjuvants mixed with soluble SIV Env or a virus-like particle form of Env (VLP) induces potent and durable Env-specific antibody responses in the serum and in vaginal secretions. These responses were superior to those induced by alum adjuvant, and they resulted in enhanced protection against a low-dose intravaginal challenge with a heterologous strain of SIV in animals with TRIM5a restrictive alleles. These results highlight the potential for such NP TLR L adjuvants in promoting robust and durable antibody responses against HIV in the next generation of HIV immunogens currently being developed.
View details for DOI 10.1128/JVI.01844-16
View details for Web of Science ID 000393883300015
View details for PubMedID 27928002
View details for PubMedCentralID PMC5286877
mTOR regulates metabolic adaptation of APCs in the lung and controls the outcome of allergic inflammation.
Science (New York, N.Y.)
2017; 357 (6355): 1014–21
Antigen-presenting cells (APCs) occupy diverse anatomical tissues, but their tissue-restricted homeostasis remains poorly understood. Here, working with mouse models of inflammation, we found that mechanistic target of rapamycin (mTOR)-dependent metabolic adaptation was required at discrete locations. mTOR was dispensable for dendritic cell (DC) homeostasis in secondary lymphoid tissues but necessary to regulate cellular metabolism and accumulation of CD103+ DCs and alveolar macrophages in lung. Moreover, while numbers of mTOR-deficient lung CD11b+ DCs were not changed, they were metabolically reprogrammed to skew allergic inflammation from eosinophilic T helper cell 2 (TH2) to neutrophilic TH17 polarity. The mechanism for this change was independent of translational control but dependent on inflammatory DCs, which produced interleukin-23 and increased fatty acid oxidation. mTOR therefore mediates metabolic adaptation of APCs in distinct tissues, influencing the immunological character of allergic inflammation.
View details for PubMedID 28798047
View details for PubMedCentralID PMC5746055
Sequential Infection with Common Pathogens Promotes Human-like Immune Gene Expression and Altered Vaccine Response
CELL HOST & MICROBE
2016; 19 (5): 713-719
Immune responses differ between laboratory mice and humans. Chronic infection with viruses and parasites are common in humans, but are absent in laboratory mice, and thus represent potential contributors to inter-species differences in immunity. To test this, we sequentially infected laboratory mice with herpesviruses, influenza, and an intestinal helminth and compared their blood immune signatures to mock-infected mice before and after vaccination against yellow fever virus (YFV-17D). Sequential infection altered pre- and post-vaccination gene expression, cytokines, and antibodies in blood. Sequential pathogen exposure induced gene signatures that recapitulated those seen in blood from pet store-raised versus laboratory mice, and adult versus cord blood in humans. Therefore, basal and vaccine-induced murine immune responses are altered by infection with agents common outside of barrier facilities. This raises the possibility that we can improve mouse models of vaccination and immunity by selective microbial exposure of laboratory animals to mimic that of humans.
View details for DOI 10.1016/j.chom.2016.04.003
View details for PubMedID 27107939
The amino acid sensor GCN2 controls gut inflammation by inhibiting inflammasome activation
2016; 531 (7595): 523-?
The integrated stress response (ISR) is a homeostatic mechanism by which eukaryotic cells sense and respond to stress-inducing signals, such as amino acid starvation. General controlled non-repressed (GCN2) kinase is a key orchestrator of the ISR, and modulates protein synthesis in response to amino acid starvation. Here we demonstrate in mice that GCN2 controls intestinal inflammation by suppressing inflammasome activation. Enhanced activation of ISR was observed in intestinal antigen presenting cells (APCs) and epithelial cells during amino acid starvation, or intestinal inflammation. Genetic deletion of Gcn2 (also known as Eif2ka4) in CD11c(+) APCs or intestinal epithelial cells resulted in enhanced intestinal inflammation and T helper 17 cell (TH17) responses, owing to enhanced inflammasome activation and interleukin (IL)-1β production. This was caused by reduced autophagy in Gcn2(-/-) intestinal APCs and epithelial cells, leading to increased reactive oxygen species (ROS), a potent activator of inflammasomes. Thus, conditional ablation of Atg5 or Atg7 in intestinal APCs resulted in enhanced ROS and TH17 responses. Furthermore, in vivo blockade of ROS and IL-1β resulted in inhibition of TH17 responses and reduced inflammation in Gcn2(-/-) mice. Importantly, acute amino acid starvation suppressed intestinal inflammation via a mechanism dependent on GCN2. These results reveal a mechanism that couples amino acid sensing with control of intestinal inflammation via GCN2.
View details for DOI 10.1038/nature17186
View details for Web of Science ID 000372701300045
View details for PubMedID 26982722
View details for PubMedCentralID PMC4854628
Systems biology of immunity to MF59-adjuvanted versus nonadjuvanted trivalent seasonal influenza vaccines in early childhood
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
2016; 113 (7): 1853-1858
The dynamics and molecular mechanisms underlying vaccine immunity in early childhood remain poorly understood. Here we applied systems approaches to investigate the innate and adaptive responses to trivalent inactivated influenza vaccine (TIV) and MF59-adjuvanted TIV (ATIV) in 90 14- to 24-mo-old healthy children. MF59 enhanced the magnitude and kinetics of serum antibody titers following vaccination, and induced a greater frequency of vaccine specific, multicytokine-producing CD4(+) T cells. Compared with transcriptional responses to TIV vaccination previously reported in adults, responses to TIV in infants were markedly attenuated, limited to genes regulating antiviral and antigen presentation pathways, and observed only in a subset of vaccinees. In contrast, transcriptional responses to ATIV boost were more homogenous and robust. Interestingly, a day 1 gene signature characteristic of the innate response (antiviral IFN genes, dendritic cell, and monocyte responses) correlated with hemagglutination at day 28. These findings demonstrate that MF59 enhances the magnitude, kinetics, and consistency of the innate and adaptive response to vaccination with the seasonal influenza vaccine during early childhood, and identify potential molecular correlates of antibody responses.
View details for DOI 10.1073/pnas.1519690113
View details for Web of Science ID 000370220000053
View details for PubMedID 26755593
View details for PubMedCentralID PMC4763735
Systems Analysis of Immunity to Influenza Vaccination across Multiple Years and in Diverse Populations Reveals Shared Molecular Signatures
2015; 43 (6): 1186-1198
Systems approaches have been used to describe molecular signatures driving immunity to influenza vaccination in humans. Whether such signatures are similar across multiple seasons and in diverse populations is unknown. We applied systems approaches to study immune responses in young, elderly, and diabetic subjects vaccinated with the seasonal influenza vaccine across five consecutive seasons. Signatures of innate immunity and plasmablasts correlated with and predicted influenza antibody titers at 1 month after vaccination with >80% accuracy across multiple seasons but were not associated with the longevity of the response. Baseline signatures of lymphocyte and monocyte inflammation were positively and negatively correlated, respectively, with antibody responses at 1 month. Finally, integrative analysis of microRNAs and transcriptomic profiling revealed potential regulators of vaccine immunity. These results identify shared vaccine-induced signatures across multiple seasons and in diverse populations and might help guide the development of next-generation vaccines that provide persistent immunity against influenza.
View details for DOI 10.1016/j.immuni.2015.11.012
View details for Web of Science ID 000366846600021
View details for PubMedID 26682988
View details for PubMedCentralID PMC4859820
Vaccinology in the era of high-throughput biology
PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY B-BIOLOGICAL SCIENCES
2015; 370 (1671)
Vaccination has been tremendously successful saving lives and preventing infections. However, the development of vaccines against global pandemics such as HIV, malaria and tuberculosis has been obstructed by several challenges. A major challenge is the lack of knowledge about the correlates and mechanisms of protective immunity. Recent advances in the application of systems biological approaches to analyse immune responses to vaccination in humans are beginning to yield new insights about mechanisms of vaccine immunity, and to define molecular signatures, induced rapidly after vaccination, that correlate with and predict vaccine induced immunity. Here, we review these advances and discuss the potential of this systems vaccinology approach in defining novel correlates of protection in clinical trials, and in infection-induced 'experimental challenge models' in humans.
View details for DOI 10.1098/rstb.2014.0146
View details for Web of Science ID 000355575800010
View details for PubMedID 25964458
View details for PubMedCentralID PMC4527391
The Varieties of Immunological Experience; Of Pathogens, Stress, and Dendritic Cells
ANNUAL REVIEW OF IMMUNOLOGY VOL 33
2015; 33: 563-606
In the 40 years since their discovery, dendritic cells (DCs) have been recognized as central players in immune regulation. DCs sense microbial stimuli through pathogen-recognition receptors (PRRs) and decode, integrate, and present information derived from such stimuli to T cells, thus stimulating immune responses. DCs can also regulate the quality of immune responses. Several functionally specialized subsets of DCs exist, but DCs also display functional plasticity in response to diverse stimuli. In addition to sensing pathogens via PRRs, emerging evidence suggests that DCs can also sense stress signals, such as amino acid starvation, through ancient stress and nutrient sensing pathways, to stimulate adaptive immunity. Here, I discuss these exciting advances in the context of a historic perspective on the discovery of DCs and their role in immune regulation. I conclude with a discussion of emerging areas in DC biology in the systems immunology era and suggest that the impact of DCs on immunity can be usefully contextualized in a hierarchy-of-organization model in which DCs, their receptors and signaling networks, cell-cell interactions, tissue microenvironment, and the host macroenvironment represent different levels of the hierarchy. Immunity or tolerance can then be represented as a complex function of each of these hierarchies.
View details for DOI 10.1146/annurev-immunol-020711-075049
View details for Web of Science ID 000352911900019
View details for PubMedID 25665078
Emerging functions of the unfolded protein response in immunity
2014; 15 (10): 910-919
The unfolded protein response (UPR) has traditionally been viewed as an adaptive response triggered by the accumulation of unfolded proteins in the endoplasmic reticulum (ER) and aimed at restoring ER function. The UPR can also be an anticipatory response that is activated well before the disruption of protein homeostasis. UPR signaling intersects at many levels with the innate and adaptive immune responses. In some types of cells of the immune system, such as dendritic cells (DCs) and B cells, particular sensors that detect the UPR seem to be constitutively active in the absence of induction of the traditional UPR gene program and are necessary for antigen presentation and immunoglobulin synthesis. The UPR also influences signaling via Toll-like receptors (TLRs) and activation of the transcription factor NF-κB, and some pathogens subvert the UPR. This Review summarizes these emerging noncanonical functions of the UPR in immunity.
View details for DOI 10.1038/ni.2991
View details for Web of Science ID 000342564800006
View details for PubMedID 25232821
View details for PubMedCentralID PMC4388558
TLR5-Mediated Sensing of Gut Microbiota Is Necessary for Antibody Responses to Seasonal Influenza Vaccination
2014; 41 (3): 478-492
Systems biological analysis of immunity to the trivalent inactivated influenza vaccine (TIV) in humans revealed a correlation between early expression of TLR5 and the magnitude of the antibody response. Vaccination of Trl5(-/-) mice resulted in reduced antibody titers and lower frequencies of plasma cells, demonstrating a role for TLR5 in immunity to TIV. This was due to a failure to sense host microbiota. Thus, antibody responses in germ-free or antibiotic-treated mice were impaired, but restored by oral reconstitution with a flagellated, but not aflagellated, strain of E. coli. TLR5-mediated sensing of flagellin promoted plasma cell differentiation directly and by stimulating lymph node macrophages to produce plasma cell growth factors. Finally, TLR5-mediated sensing of the microbiota also impacted antibody responses to the inactivated polio vaccine, but not to adjuvanted vaccines or the live-attenuated yellow fever vaccine. These results reveal an unappreciated role for gut microbiota in promoting immunity to vaccination.
View details for DOI 10.1016/j.immuni.2014.08.009
View details for Web of Science ID 000342626500017
View details for PubMedID 25220212
View details for PubMedCentralID PMC4169736
Systems vaccinology: Probing humanity's diverse immune systems with vaccines
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
2014; 111 (34): 12300-12306
Homo sapiens are genetically diverse, but dramatic demographic and socioeconomic changes during the past century have created further diversification with respect to age, nutritional status, and the incidence of associated chronic inflammatory disorders and chronic infections. These shifting demographics pose new challenges for vaccination, as emerging evidence suggests that age, the metabolic state, and chronic infections can exert major influences on the immune system. Thus, a key public health challenge is learning how to reprogram suboptimal immune systems to induce effective vaccine immunity. Recent advances have applied systems biological analysis to define molecular signatures induced early after vaccination that correlate with and predict the later adaptive immune responses in humans. Such "systems vaccinology" approaches offer an integrated picture of the molecular networks driving vaccine immunity, and are beginning to yield novel insights about the immune system. Here we discuss the promise of systems vaccinology in probing humanity's diverse immune systems, and in delineating the impact of genes, the environment, and the microbiome on protective immunity induced by vaccination. Such insights will be critical in reengineering suboptimal immune systems in immunocompromised populations.
View details for DOI 10.1073/pnas.1400476111
View details for Web of Science ID 000340780300021
View details for PubMedID 25136102
View details for PubMedCentralID PMC4151766
Dengue Virus Infection Induces Expansion of a CD14(+)CD16(+) Monocyte Population that Stimulates Plasmablast Differentiation
CELL HOST & MICROBE
2014; 16 (1): 115-127
Dengue virus (DENV) infection induces the expansion of plasmablasts, which produce antibodies that can neutralize DENV but also enhance disease upon secondary infection with another DENV serotype. To understand how these immune responses are generated, we used a systems biological approach to analyze immune responses to dengue in humans. Transcriptomic analysis of whole blood revealed that genes encoding proinflammatory mediators and type I interferon-related proteins were associated with high DENV levels during initial symptomatic disease. Additionally, CD14(+)CD16(+) monocytes increased in the blood. Similarly, in a nonhuman primate model, DENV infection boosted CD14(+)CD16(+) monocyte numbers in the blood and lymph nodes. Upon DENV infection in vitro, monocytes upregulated CD16 and mediated differentiation of resting B cells to plasmablasts as well as immunoglobulin G (IgG) and IgM secretion. These findings provide a detailed picture of innate responses to dengue and highlight a role for CD14(+)CD16(+) monocytes in promoting plasmablast differentiation and anti-DENV antibody responses.
View details for DOI 10.1016/j.chom.2014.06.001
View details for Web of Science ID 000341142600014
View details for PubMedID 24981333
View details for PubMedCentralID PMC4116428
Molecular signatures of antibody responses derived from a systems biology study of five human vaccines
2014; 15 (2): 195-204
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.
View details for DOI 10.1038/ni.2789
View details for Web of Science ID 000330150600014
View details for PubMedID 24336226
View details for PubMedCentralID PMC3946932
Vaccine Activation of the Nutrient Sensor GCN2 in Dendritic Cells Enhances Antigen Presentation
2014; 343 (6168): 313-317
The yellow fever vaccine YF-17D is one of the most successful vaccines ever developed in humans. Despite its efficacy and widespread use in more than 600 million people, the mechanisms by which it stimulates protective immunity remain poorly understood. Recent studies using systems biology approaches in humans have revealed that YF-17D-induced early expression of general control nonderepressible 2 kinase (GCN2) in the blood strongly correlates with the magnitude of the later CD8(+) T cell response. We demonstrate a key role for virus-induced GCN2 activation in programming dendritic cells to initiate autophagy and enhanced antigen presentation to both CD4(+) and CD8(+) T cells. These results reveal an unappreciated link between virus-induced integrated stress response in dendritic cells and the adaptive immune response.
View details for DOI 10.1126/science.1246829
View details for Web of Science ID 000329718600040
View details for PubMedID 24310610
View details for PubMedCentralID PMC4048998
Chronic but Not Acute Virus Infection Induces Sustained Expansion of Myeloid Suppressor Cell Numbers that Inhibit Viral-Specific T Cell Immunity
2013; 38 (2): 309-321
Resolution of acute and chronic viral infections requires activation of innate cells to initiate and maintain adaptive immune responses. Here we report that infection with acute Armstrong (ARM) or chronic Clone 13 (C13) strains of lymphocytic choriomeningitis virus (LCMV) led to two distinct phases of innate immune response. During the first 72 hr of infection, dendritic cells upregulated activation markers and stimulated antiviral CD8(+) T cells, independent of viral strain. Seven days after infection, there was an increase in Ly6C(hi) monocytic and Gr-1(hi) neutrophilic cells in lymphoid organs and blood. This expansion in cell numbers was enhanced and sustained in C13 infection, whereas it occurred only transiently with ARM infection. These cells resembled myeloid-derived suppressor cells and potently suppressed T cell proliferation. The reduction of monocytic cells in Ccr2(-/-) mice or after Gr-1 antibody depletion enhanced antiviral T cell function. Thus, innate cells have an important immunomodulatory role throughout chronic infection.
View details for DOI 10.1016/j.immuni.2012.10.022
View details for Web of Science ID 000330940800013
View details for PubMedID 23438822
View details for PubMedCentralID PMC3869405
Systems Biology of Vaccination in the Elderly
2013; 363: 117-142
Aging population demographics, combined with suboptimal vaccine responses in the elderly, make the improvement of vaccination strategies in the elderly a developing public health issue. The immune system changes with age, with innate and adaptive cell components becoming increasingly dysfunctional. As such, vaccine responses in the elderly are impaired in ways that differ depending on the type of vaccine (e.g., live attenuated, polysaccharide, conjugate, or subunit) and the mediators of protection (e.g., antibody and/or T cell). The rapidly progressing field of systems biology has been shown to be useful in predicting immunogenicity and offering insights into potential mechanisms of protection in young adults. Future application of systems biology to vaccination in the elderly may help to identify gene signatures that predict suboptimal responses and help to identify more accurate correlates of protection. Moreover, the identification of specific defects may be used to target novel vaccination strategies that improve efficacy in elderly populations.
View details for DOI 10.1007/82_2012_250
View details for Web of Science ID 000330590200008
View details for PubMedID 22903566
A Blueprint for HIV Vaccine Discovery
CELL HOST & MICROBE
2012; 12 (4): 396-407
Despite numerous attempts over many years to develop an HIV vaccine based on classical strategies, none has convincingly succeeded to date. A number of approaches are being pursued in the field, including building upon possible efficacy indicated by the recent RV144 clinical trial, which combined two HIV vaccines. Here, we argue for an approach based, in part, on understanding the HIV envelope spike and its interaction with broadly neutralizing antibodies (bnAbs) at the molecular level and using this understanding to design immunogens as possible vaccines. BnAbs can protect against virus challenge in animal models, and many such antibodies have been isolated recently. We further propose that studies focused on how best to provide T cell help to B cells that produce bnAbs are crucial for optimal immunization strategies. The synthesis of rational immunogen design and immunization strategies, together with iterative improvements, offers great promise for advancing toward an HIV vaccine.
View details for DOI 10.1016/j.chom.2012.09.008
View details for Web of Science ID 000310719700004
View details for PubMedID 23084910
View details for PubMedCentralID PMC3513329
New Paradigms in Type 2 Immunity
2012; 337 (6093): 431-435
Nearly half of the world's population harbors helminth infections or suffers from allergic disorders. A common feature of this population is the so-called "type 2 immune response," which confers protection against helminths, but also promotes pathologic responses associated with allergic inflammation. However, the mechanisms that initiate and control type 2 responses remain enigmatic. Recent advances have revealed a role for the innate immune system in orchestrating type 2 responses against a bewildering array of stimuli, from nanometer-sized allergens to 20-meter-long helminth parasites. Here, we review these advances and suggest that the human immune system has evolved multiple mechanisms of sensing such stimuli, from recognition of molecular patterns via innate immune receptors to detecting metabolic changes and tissue damage caused by these stimuli.
View details for DOI 10.1126/science.1221064
View details for Web of Science ID 000306802300033
View details for PubMedID 22837519
View details for PubMedCentralID PMC4078898
Distinct TLR adjuvants differentially stimulate systemic and local innate immune responses in nonhuman primates
2012; 119 (9): 2044-2055
TLR ligands (TLR-Ls) represent novel vaccine adjuvants, but their immunologic effects in humans remain poorly defined in vivo. In the present study, we analyzed the innate responses stimulated by different TLR-Ls in rhesus macaques. MPL (TLR4-L), R-848 (TLR7/8-L), or cytosine-phosphate-guanine oligodeoxynucleotide (TLR9-L) induced a rapid and robust expansion of blood neutrophils, with a concomitant reduction in PBMCs. Furthermore, all TLR-Ls induced rapid (3-8 hours) expansion of CD14(+) monocytes, but only TLR7/8-L and TLR9-L mobilized the CD14(+)CD16(+) and CD14(dim)CD16(++) monocytes, and only TLR7/8-L and TLR9-L induced activation of myeloid dendritic cells (mDCs) and plasmacytoid DCs (pDCs), production of IP-10 and type-I IFN, and expression of type-I IFN-related and chemokine genes in the blood. In the draining lymph nodes (LNs), consistent with the effects in blood, all TLR-Ls induced expansion of CD14(+) monocytes, but only TLR7/8-L and TLR9-L expanded the activated CD14(+)CD16(+) cells. TLR4-L and TLR9-L differentially induced the expansion of mDCs and pDCs (1-3 days), but did not activate DCs. In contrast, TLR7/8-L did not induce DC expansion, but did activate mDCs. Finally, both TLR9-L and TLR7/8-L induced the expression of genes related to chemokines and type-I IFNs in LNs. Thus different TLR-Ls mediate distinct signatures of early innate responses both locally and systemically.
View details for DOI 10.1182/blood-2011-10-388579
View details for Web of Science ID 000300949500014
View details for PubMedID 22246032
View details for PubMedCentralID PMC3311246
Learning vaccinology from viral infections
JOURNAL OF EXPERIMENTAL MEDICINE
2011; 208 (12): 2347-2349
This issue of the Journal of Experimental Medicine celebrates and honors the life of Ralph Steinman (1943-2011), winner of the 2011 Nobel Prize in Physiology or Medicine. Ralph's science was rooted in fundamental discovery with the goal of translating these findings into clinical medicine. He recognized the power of immunology in treating human disease and passionately championed studies on vaccine design, immune therapy, and human immunology. One particular collaborative effort between the Steinman and Sekaly laboratories resulted in a paper published in this issue of the journal.
View details for DOI 10.1084/jem.20112321
View details for Web of Science ID 000297870700003
View details for PubMedID 22110181
View details for PubMedCentralID PMC3256975
Systems biology of vaccination for seasonal influenza in humans
2011; 12 (8): 786-U149
Here we have used a systems biology approach to study innate and adaptive responses to vaccination against influenza in humans during three consecutive influenza seasons. We studied healthy adults vaccinated with trivalent inactivated influenza vaccine (TIV) or live attenuated influenza vaccine (LAIV). TIV induced higher antibody titers and more plasmablasts than LAIV did. In subjects vaccinated with TIV, early molecular signatures correlated with and could be used to accurately predict later antibody titers in two independent trials. Notably, expression of the kinase CaMKIV at day 3 was inversely correlated with later antibody titers. Vaccination of CaMKIV-deficient mice with TIV induced enhanced antigen-specific antibody titers, which demonstrated an unappreciated role for CaMKIV in the regulation of antibody responses. Thus, systems approaches can be used to predict immunogenicity and provide new mechanistic insights about vaccines.
View details for DOI 10.1038/ni.2067
View details for Web of Science ID 000292870700017
View details for PubMedID 21743478
View details for PubMedCentralID PMC3140559
Functional Specializations of Intestinal Dendritic Cell and Macrophage Subsets That Control Th17 and Regulatory T Cell Responses Are Dependent on the T Cell/APC Ratio, Source of Mouse Strain, and Regional Localization
JOURNAL OF IMMUNOLOGY
2011; 187 (2): 733-747
Although several subsets of intestinal APCs have been described, there has been no systematic evaluation of their phenotypes, functions, and regional localization to date. In this article, we used 10-color flow cytometry to define the major APC subsets in the small and large intestine lamina propria. Lamina propria APCs could be subdivided into CD11c(+)CD11b(-), CD11c(+)CD11b(+), and CD11c(dull)CD11b(+) subsets. CD11c(+)CD11b(-) cells were largely CD103(+)F4/80(-) dendritic cells (DCs), whereas the CD11c(+)CD11b(+) subset comprised CD11c(+)CD11b(+)CD103(+)F4/80(-) DCs and CD11c(+)CD11b(+)CD103(-)F4/80(+) macrophage-like cells. The majority of CD11c(dull)CD11b(+) cells were CD103(-)F4/80(+) macrophages. Although macrophages were more efficient at inducing Foxp3(+) regulatory T (T(reg)) cells than DCs, at higher T cell/APC ratios, all of the DC subsets efficiently induced Foxp3(+) T(reg) cells. In contrast, only CD11c(+)CD11b(+)CD103(+) DCs efficiently induced Th17 cells. Consistent with this, the regional distribution of CD11c(+)CD11b(+)CD103(+) DCs correlated with that of Th17 cells, with duodenum > jejunum > ileum > colon. Conversely, CD11c(+)CD11b(-)CD103(+) DCs, macrophages, and Foxp3(+) T(reg) cells were most abundant in the colon and scarce in the duodenum. Importantly, however, the ability of DC and macrophage subsets to induce Foxp3(+) T(reg) cells versus Th17 cells was strikingly dependent on the source of the mouse strain. Thus, DCs from C57BL/6 mice from Charles River Laboratories (that have segmented filamentous bacteria, which induce robust levels of Th17 cells in situ) were more efficient at inducing Th17 cells and less efficient at inducing Foxp3(+) T(reg) cells than DCs from B6 mice from The Jackson Laboratory. Thus, the functional specializations of APC subsets in the intestine are dependent on the T cell/APC ratio, regional localization, and source of the mouse strain.
View details for DOI 10.4049/jimmunol.1002701
View details for Web of Science ID 000292451000020
View details for PubMedID 21666057
View details for PubMedCentralID PMC3131424
Immunological mechanisms of vaccination
2011; 12 (6): 509-517
Vaccines represent one of the greatest triumphs of modern medicine. Despite the common origins of vaccinology and immunology more than 200 years ago, the two disciplines have evolved along such different trajectories that most of the highly successful vaccines have been made empirically, with little or no immunological insight. Recent advances in innate immunity have offered new insights about the mechanisms of vaccine-induced immunity and have facilitated a more rational approach to vaccine design. Here we will discuss these advances and emerging themes on the immunology of vaccination.
View details for DOI 10.1038/ni.2039
View details for Web of Science ID 000290707100009
View details for PubMedID 21739679
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Dendritic cell control of tolerogenic responses
2011; 241: 206-227
One of the most fundamental problems in immunology is the seemingly schizophrenic ability of the immune system to launch robust immunity against pathogens, while acquiring and maintaining a state of tolerance to the body's own tissues and the trillions of commensal microorganisms and food antigens that confront it every day. A fundamental role for the innate immune system, particularly dendritic cells (DCs), in orchestrating immunological tolerance has been appreciated, but emerging studies have highlighted the nature of the innate receptors and the signaling pathways that program DCs to a tolerogenic state. Furthermore, several studies have emphasized the major role played by cellular interactions and the microenvironment in programming tolerogenic DCs. Here, we review these studies and suggest that the innate control of tolerogenic responses can be viewed as different hierarchies of organization, in which DCs, their innate receptors and signaling networks, and their interactions with other cells and local microenvironments represent different levels of the hierarchy.
View details for DOI 10.1111/j.1600-065X.2011.01015.x
View details for Web of Science ID 000289468700014
View details for PubMedID 21488899
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Programming the magnitude and persistence of antibody responses with innate immunity
2011; 470 (7335): 543-U136
Many successful vaccines induce persistent antibody responses that can last a lifetime. The mechanisms by which they do so remain unclear, but emerging evidence indicates that they activate dendritic cells via Toll-like receptors (TLRs). For example, the yellow fever vaccine YF-17D, one of the most successful empiric vaccines ever developed, activates dendritic cells via multiple TLRs to stimulate proinflammatory cytokines. Triggering specific combinations of TLRs in dendritic cells can induce synergistic production of cytokines, which results in enhanced T-cell responses, but its impact on antibody responses remain unknown. Learning the critical parameters of innate immunity that program such antibody responses remains a major challenge in vaccinology. Here we demonstrate that immunization of mice with synthetic nanoparticles containing antigens plus ligands that signal through TLR4 and TLR7 induces synergistic increases in antigen-specific, neutralizing antibodies compared to immunization with nanoparticles containing antigens plus a single TLR ligand. Consistent with this there was enhanced persistence of germinal centres and of plasma-cell responses, which persisted in the lymph nodes for >1.5 years. Surprisingly, there was no enhancement of the early short-lived plasma-cell response relative to that observed with single TLR ligands. Molecular profiling of activated B cells, isolated 7 days after immunization, indicated that there was early programming towards B-cell memory. Antibody responses were dependent on direct triggering of both TLRs on B cells and dendritic cells, as well as on T-cell help. Immunization protected completely against lethal avian and swine influenza virus strains in mice, and induced robust immunity against pandemic H1N1 influenza in rhesus macaques.
View details for DOI 10.1038/nature09737
View details for Web of Science ID 000287652900044
View details for PubMedID 21350488
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2010; 33 (4): 516-529
Vaccination is one of the greatest triumphs of modern medicine, yet we remain largely ignorant of the mechanisms by which successful vaccines stimulate protective immunity. Two recent advances are beginning to illuminate such mechanisms: realization of the pivotal role of the innate immune system in sensing microbes and stimulating adaptive immunity, and advances in systems biology. Recent studies have used systems biology approaches to obtain a global picture of the immune responses to vaccination in humans. This has enabled the identification of early innate signatures that predict the immunogenicity of vaccines, and identification of potentially novel mechanisms of immune regulation. Here, we review these advances and critically examine the potential opportunities and challenges posed by systems biology in vaccine development.
View details for DOI 10.1016/j.immuni.2010.10.006
View details for Web of Science ID 000284300200008
View details for PubMedID 21029962
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Activation of beta-Catenin in Dendritic Cells Regulates Immunity Versus Tolerance in the Intestine
2010; 329 (5993): 849-853
Dendritic cells (DCs) play a vital role in initiating robust immunity against pathogens as well as maintaining immunological tolerance to self antigens. However, the intracellular signaling networks that program DCs to become tolerogenic remain unknown. We report here that the Wnt-beta-catenin signaling in intestinal dendritic cells regulates the balance between inflammatory versus regulatory responses in the gut. beta-catenin in intestinal dendritic cells was required for the expression of anti-inflammatory mediators such as retinoic acid-metabolizing enzymes, interleukin-10, and transforming growth factor-beta, and the stimulation of regulatory T cell induction while suppressing inflammatory effector T cells. Furthermore, ablation of beta-catenin expression in DCs enhanced inflammatory responses and disease in a mouse model of inflammatory bowel disease. Thus, beta-catenin signaling programs DCs to a tolerogenic state, limiting the inflammatory response.
View details for DOI 10.1126/science.1188510
View details for Web of Science ID 000280809900053
View details for PubMedID 20705860
View details for PubMedCentralID PMC3732486
Programming dendritic cells to induce T(H)2 and tolerogenic responses
2010; 11 (8): 647-655
A fundamental puzzle in immunology is how the immune system decides what types of immune responses to launch against different stimuli. Although much is known about control of T helper type 1 (T(H)1) and T(H)17 responses, the mechanisms that initiate T(H)2 and T regulatory (T(reg)) responses remain obscure. Emerging studies suggest a fundamental role for the innate immune system, particularly dendritic cells (DCs), in this process. We review these studies, and suggest that the innate control of T(H)2 and T(reg) responses can be viewed as different hierarchies of organization, in which DCs, their innate receptors and signaling networks, and their interactions with other cells and local microenvironments represent different levels of the hierarchy.
View details for DOI 10.1038/ni.1894
View details for Web of Science ID 000280149400002
View details for PubMedID 20644570
The T helper type 2 response to cysteine proteases requires dendritic cell-basophil cooperation via ROS-mediated signaling
2010; 11 (7): 608-U80
The mechanisms that initiate T helper type 2 (T(H)2) responses are poorly understood. Here we demonstrate that cysteine protease-induced T(H)2 responses occur via 'cooperation' between migratory dermal dendritic cells (DCs) and basophils positive for interleukin 4 (IL-4). Subcutaneous immunization with papain plus antigen induced reactive oxygen species (ROS) in lymph node DCs and in dermal DCs and epithelial cells of the skin. ROS orchestrated T(H)2 responses by inducing oxidized lipids that triggered the induction of thymic stromal lymphopoietin (TSLP) by epithelial cells mediated by Toll-like receptor 4 (TLR4) and the adaptor protein TRIF; by suppressing production of the T(H)1-inducing molecules IL-12 and CD70 in lymph node DCs; and by inducing the DC-derived chemokine CCL7, which mediated recruitment of IL-4(+) basophils to the lymph node. Thus, the T(H)2 response to cysteine proteases requires DC-basophil cooperation via ROS-mediated signaling.
View details for DOI 10.1038/ni.1883
View details for Web of Science ID 000278926400017
View details for PubMedID 20495560
View details for PubMedCentralID PMC3145206
Learning immunology from the yellow fever vaccine: innate immunity to systems vaccinology
NATURE REVIEWS IMMUNOLOGY
2009; 9 (10): 741-747
Despite their great success, we understand little about how effective vaccines stimulate protective immune responses. Two recent developments promise to yield such understanding: the appreciation of the crucial role of the innate immune system in sensing microorganisms and tuning immune responses, and advances in systems biology. Here I review how these developments are yielding insights into the mechanism of action of the yellow fever vaccine, one of the most successful vaccines ever developed, and the broader implications for vaccinology.
View details for DOI 10.1038/nri2629
View details for Web of Science ID 000270133000018
View details for PubMedID 19763148
Toll-like receptor 2-dependent induction of vitamin A-metabolizing enzymes in dendritic cells promotes T regulatory responses and inhibits autoimmunity
2009; 15 (4): 401-409
Immune sensing of a microbe occurs via multiple receptors. How signals from different receptors are coordinated to yield a specific immune response is poorly understood. We show that two pathogen recognition receptors, Toll-like receptor 2 (TLR2) and dectin-1, recognizing the same microbial stimulus, stimulate distinct innate and adaptive responses. TLR2 signaling induced splenic dendritic cells (DCs) to express the retinoic acid metabolizing enzyme retinaldehyde dehydrogenase type 2 and interleukin-10 (IL-10) and to metabolize vitamin A and stimulate Foxp3(+) T regulatory cells (T(reg) cells). Retinoic acid acted on DCs to induce suppressor of cytokine signaling-3 expression, which suppressed activation of p38 mitogen-activated protein kinase and proinflammatory cytokines. Consistent with this finding, TLR2 signaling induced T(reg) cells and suppressed IL-23 and T helper type 17 (T(H)17) and T(H)1-mediated autoimmune responses in vivo. In contrast, dectin-1 signaling mostly induced IL-23 and proinflammatory cytokines and augmented T(H)17 and T(H)1-mediated autoimmune responses in vivo. These data define a new mechanism for the systemic induction of retinoic acid and immune suppression against autoimmunity.
View details for DOI 10.1038/nm.1925
View details for Web of Science ID 000264937200027
View details for PubMedID 19252500
View details for PubMedCentralID PMC2768543
Systems biology approach predicts immunogenicity of the yellow fever vaccine in humans
2009; 10 (1): 116-125
A major challenge in vaccinology is to prospectively determine vaccine efficacy. Here we have used a systems biology approach to identify early gene 'signatures' that predicted immune responses in humans vaccinated with yellow fever vaccine YF-17D. Vaccination induced genes that regulate virus innate sensing and type I interferon production. Computational analyses identified a gene signature, including complement protein C1qB and eukaryotic translation initiation factor 2 alpha kinase 4-an orchestrator of the integrated stress response-that correlated with and predicted YF-17D CD8(+) T cell responses with up to 90% accuracy in an independent, blinded trial. A distinct signature, including B cell growth factor TNFRS17, predicted the neutralizing antibody response with up to 100% accuracy. These data highlight the utility of systems biology approaches in predicting vaccine efficacy.
View details for DOI 10.1038/ni.1688
View details for Web of Science ID 000261788800019
View details for PubMedID 19029902
View details for PubMedCentralID PMC4049462
Lamina propria macrophages and dendritic cells differentially induce regulatory and interleukin 17-producing T cell responses
2007; 8 (10): 1086-1094
The intestinal immune system must elicit robust immunity against harmful pathogens but must also restrain immune responses directed against commensal microbes and dietary antigens. The mechanisms that maintain this dichotomy are poorly understood. Here we describe a population of CD11b+F4/80+CD11c- macrophages in the lamina propria that expressed several anti-inflammatory molecules, including interleukin 10 (IL-10), but little or no proinflammatory cytokines, even after stimulation with Toll-like receptor ligands. These macrophages induced, by a mechanism dependent on IL-10, retinoic acid and exogenous transforming growth factor-beta, the differentiation of Foxp3+ regulatory T cells. In contrast, lamina propria CD11b+ dendritic cells elicited IL-17 production. This IL-17 production was suppressed by lamina propria macrophages, indicating that a dynamic interaction between these subsets may influence the balance between immune activation and tolerance.
View details for DOI 10.1038/ni1511
View details for Web of Science ID 000249691400023
View details for PubMedID 17873879
Translating innate immunity into immunological memory: Implications for vaccine development
2006; 124 (4): 849-863
Vaccination is the most effective means of preventing infectious diseases. Despite the success of many vaccines, there is presently little knowledge of the immunological mechanisms that mediate their efficacy. Such information will be critical in the design of future vaccines against old and new infectious diseases. Recent advances in immunology are beginning to provide an intellectual framework with which to address fundamental questions about how the innate immune system shapes adaptive immunity. In this review, we summarize current knowledge about how the innate immune system modulates the quantity and quality of long-term T and B cell memory and protective immune responses to pathogens. In addition, we point out unanswered questions and identify critical challenges, the solution of which, we believe, will greatly facilitate the rational design of novel vaccines against a multitude of emerging infections.
View details for DOI 10.1016/j.cell.2006.02.019
View details for Web of Science ID 000237240900026
View details for PubMedID 16497593
Yellow fever vaccine YF-17D activates multiple dendritic cell subsets via TLR2, 7, 8, and 9 to stimulate polyvalent immunity
JOURNAL OF EXPERIMENTAL MEDICINE
2006; 203 (2): 413-424
The live attenuated yellow fever vaccine 17D (YF-17D) is one of the most effective vaccines available, with a 65-yr history of use in >400 million people globally. Despite this efficacy, there is presently no information about the immunological mechanisms by which YF-17D acts. Here, we present data that suggest that YF-17D activates multiple Toll-like receptors (TLRs) on dendritic cells (DCs) to elicit a broad spectrum of innate and adaptive immune responses. Specifically, YF-17D activates multiple DC subsets via TLRs 2, 7, 8, and 9 to elicit the proinflammatory cytokines interleukin (IL)-12p40, IL-6, and interferon-alpha. Interestingly, the resulting adaptive immune responses are characterized by a mixed T helper cell (Th)1/Th2 cytokine profile and antigen-specific CD8+ T cells. Furthermore, distinct TLRs appear to differentially control the Th1/Th2 balance; thus, whilst MyD88-deficient mice show a profound impairment of Th1 cytokines, TLR2-deficient mice show greatly enhanced Th1 and Tc1 responses to YF-17D. Together, these data enhance our understanding of the molecular mechanism of action of YF-17D, and highlight the potential of vaccination strategies that use combinations of different TLR ligands to stimulate polyvalent immune responses.
View details for DOI 10.1084/jem.20051720
View details for Web of Science ID 000235707700020
View details for PubMedID 16461338
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Cutting edge: Different toll-like receptor agonists instruct dendritic cells to induce distinct th responses via differential modulation of extracellular signal-regulated kinase-mitogen-activated protein kinase and c-fos
JOURNAL OF IMMUNOLOGY
2003; 171 (10): 4984-4989
Dendritic cells (DCs) are pivotal in determining the class of an adaptive immune response. However, the molecular mechanisms within DCs that determine this decision-making process are unknown. Here, we demonstrate that distinct Toll-like receptor (TLR) ligands instruct human DCs to induce distinct Th cell responses by differentially modulating mitogen-activated protein kinase signaling. Thus, Escherichia coli LPS and flagellin, which trigger TLR4 and TLR5, respectively, instruct DCs to stimulate Th1 responses via IL-12p70 production, which depends on the phosphorylation of p38 and c-Jun N-terminal kinase 1/2. In contrast, the TLR2 agonist, Pam3cys, and the Th2 stimulus, schistosome egg Ags: 1) barely induce IL-12p70; 2) stimulate sustained duration and magnitude of extracellular signal-regulated kinase 1/2 phosphorylation, which results in stabilization of the transcription factor c-Fos, a suppressor of IL-12; and 3) yield a Th2 bias. Thus, distinct TLR agonists differentially modulate extracellular signal-regulated kinase signaling, c-Fos activity, and cytokine responses in DCs to stimulate different Th responses.
View details for Web of Science ID 000186643300007
View details for PubMedID 14607893
Impairment of dendritic cells and adaptive immunity by anthrax lethal toxin
2003; 424 (6946): 329-334
Anthrax poses a clear and present danger as an agent of biological terrorism. Infection with Bacillus anthracis, the causative agent of anthrax, if untreated can result in rampant bacteraemia, multisystem dysfunction and death. Anthrax lethal toxin (LT) is a critical virulence factor of B. anthracis, which occurs as a complex of protective antigen and lethal factor. Here we demonstrate that LT severely impairs the function of dendritic cells--which are pivotal to the establishment of immunity against pathogens--and host immune responses by disrupting the mitogen-activated protein (MAP) kinase intracellular signalling network. Dendritic cells exposed to LT and then stimulated with lipopolysaccharide do not upregulate co-stimulatory molecules, secrete greatly diminished amounts of proinflammatory cytokines, and do not effectively stimulate antigen-specific T cells in vivo. Furthermore, injections of LT induce a profound impairment of antigen-specific T- and B-cell immunity. These data suggest a role for LT in suppressing host immunity during B. anthracis infections, and represent an immune evasion strategy, where a microbe targets MAP kinases in dendritic cells to disarm the immune response.
View details for DOI 10.1038/nature01794
View details for Web of Science ID 000184183900046
View details for PubMedID 12867985
Cutting edge: impairment of dendritic cells and adaptive immunity by Ebola and Lassa viruses.
Journal of immunology
2003; 170 (6): 2797-2801
Acute infection of humans with Ebola and Lassa viruses, two principal etiologic agents of hemorrhagic fevers, often results in a paradoxical pattern of immune responses: early infection, characterized by an outpouring of inflammatory mediators such as TNF-alpha, IL-1 beta, and IL-6, vs late stage infections, which are associated with poor immune responses. The mechanisms underlying these diverse outcomes are poorly understood. In particular, the role played by cells of the innate immune system, such as dendritic cells (DC), is not known. In this study, we show that Ebola and Lassa viruses infect human monocyte-derived DC and impair their function. Monocyte-derived DC exposed to either virus fail to secrete proinflammatory cytokines, do not up-regulate costimulatory molecules, and are poor stimulators of T cells. These data represent the first evidence for a mechanism by which Ebola and Lassa viruses target DC to impair adaptive immunity.
View details for PubMedID 12626527
Lipopolysaccharides from distinct pathogens induce different classes of immune responses in vivo
JOURNAL OF IMMUNOLOGY
2001; 167 (9): 5067-5076
The adaptive immune system has evolved distinct responses against different pathogens, but the mechanism(s) by which a particular response is initiated is poorly understood. In this study, we investigated the type of Ag-specific CD4(+) Th and CD8(+) T cell responses elicited in vivo, in response to soluble OVA, coinjected with LPS from two different pathogens. We used Escherichia coli LPS, which signals through Toll-like receptor 4 (TLR4) and LPS from the oral pathogen Porphyromonas gingivalis, which does not appear to require TLR4 for signaling. Coinjections of E. coli LPS + OVA or P. gingivalis LPS + OVA induced similar clonal expansions of OVA-specific CD4(+) and CD8(+) T cells, but strikingly different cytokine profiles. E. coli LPS induced a Th1-like response with abundant IFN-gamma, but little or no IL-4, IL-13, and IL-5. In contrast, P. gingivalis LPS induced Th and T cell responses characterized by significant levels of IL-13, IL-5, and IL-10, but lower levels of IFN-gamma. Consistent with these results, E. coli LPS induced IL-12(p70) in the CD8alpha(+) dendritic cell (DC) subset, while P. gingivalis LPS did not. Both LPS, however, activated the two DC subsets to up-regulate costimulatory molecules and produce IL-6 and TNF-alpha. Interestingly, these LPS appeared to have differences in their ability to signal through TLR4; proliferation of splenocytes and cytokine secretion by splenocytes or DCs from TLR4-deficient C3H/HeJ mice were greatly impaired in response to E. coli LPS, but not P. gingivalis LPS. Therefore, LPS from different bacteria activate DC subsets to produce different cytokines, and induce distinct types of adaptive immunity in vivo.
View details for Web of Science ID 000171858500037
View details for PubMedID 11673516
View details for PubMedCentralID PMC3739327
Sensing pathogens and tuning immune responses
2001; 293 (5528): 253-256
The immune system is capable of making qualitatively distinct responses against different microbial infections, and recent advances are starting to reveal how it manages this complex task. An integral component of the immune system is a network of cells known as dendritic cells (DCs), which sense different microbial stimuli and convey this information to lymphocytes. A better understanding of DC biology has allowed a model to be constructed in which the type of immune response to an infection is viewed as a function of several determinants, including the subpopulation of DCs, the nature of the microbe, microbe recognition receptors, and the cytokine microenvironment.
View details for Web of Science ID 000169875200046
View details for PubMedID 11452116
Flt3-ligand and granulocyte colony-stimulating factor mobilize distinct human dendritic cell subsets in vivo
JOURNAL OF IMMUNOLOGY
2000; 165 (1): 566-572
Dendritic cells (DCs) have a unique ability to stimulate naive T cells. Recent evidence suggests that distinct DC subsets direct different classes of immune responses in vitro and in vivo. In humans, the monocyte-derived CD11c+ DCs induce T cells to produce Th1 cytokines in vitro, whereas the CD11c- plasmacytoid T cell-derived DCs elicit the production of Th2 cytokines. In this paper we report that administration of either Flt3-ligand (FL) or G-CSF to healthy human volunteers dramatically increases distinct DC subsets, or DC precursors, in the blood. FL increases both the CD11c+ DC subset (48-fold) and the CD11c- IL-3R+ DC precursors (13-fold). In contrast, G-CSF only increases the CD11c- precursors (>7-fold). Freshly sorted CD11c+ but not CD11c- cells stimulate CD4+ T cells in an allogeneic MLR, whereas only the CD11c- cells can be induced to secrete high levels of IFN-alpha, in response to influenza virus. CD11c+ and CD11c- cells can mature in vitro with GM-CSF + TNF-alpha or with IL-3 + CD40 ligand, respectively. These two subsets up-regulate MHC class II costimulatory molecules as well as the DC maturation marker DC-lysosome-associated membrane protein, and they stimulate naive, allogeneic CD4+ T cells efficiently. These two DC subsets elicit distinct cytokine profiles in CD4+ T cells, with the CD11c- subset inducing higher levels of the Th2 cytokine IL-10. The differential mobilization of distinct DC subsets or DC precursors by in vivo administration of FL and G-CSF offers a novel strategy to manipulate immune responses in humans.
View details for Web of Science ID 000087816800072
View details for PubMedID 10861097
Polyethylene glycol-modified GM-CSF expands CD11b(high)CD11c(high) but not CD11b(low)CD11c(high) murine dendritic cells in vivo: A comparative analysis with Flt3 ligand
JOURNAL OF IMMUNOLOGY
2000; 165 (1): 49-58
Dendritic cells (DC) are potent APCs that can be characterized in the murine spleen as CD11b(high)CD11c(high) or CD11b(low)CD11c(high). Daily injection of mice of Flt3 ligand (FL) into mice transiently expands both subsets of DC in vivo, but the effect of administration of GM-CSF on the expansion of DC in vivo is not well defined. To gain further insight into the role of GM-CSF in DC development and function in vivo, we treated mice with polyethylene glycol-modified GM-CSF (pGM-CSF) which has an increased half-life in vivo. Administration of pGM-CSF to mice for 5 days led to a 5- to 10-fold expansion of CD11b(high)CD11c(high) but not CD11b(low)CD11c(high) DC. DC from pGM-CSF-treated mice captured and processed Ag more efficiently than DC from FL-treated mice. Although both FL- and pGM-CSF-generated CD11b(high)CD11c(high) DC were CD8alpha-, a greater proportion of these DC from pGM-CSF-treated mice were 33D1+ than from FL-treated mice. CD11b(low)CD11c(high) DC from FL-treated mice expressed high levels of intracellular MHC class II. DC from both pGM-CSF- and FL-treated mice expressed high levels of surface class II, low levels of the costimulatory molecules CD40, CD80, and CD86 and were equally efficient at stimulating allogeneic and Ag-specific T cell proliferation in vitro. The data demonstrate that treatment with pGM-CSF in vivo preferentially expands CD11b(high)CD11c(high) DC that share phenotypic and functional characteristics with FL-generated CD11b(high)CD11c(high) DC but can be distinguished from FL-generated DC on the basis of Ag capture and surface expression of 33D1.
View details for Web of Science ID 000087816800009
View details for PubMedID 10861034
Mice lacking flt3 ligand have deficient hematopoiesis affecting hematopoietic progenitor cells, dendritic cells, and natural killer cells
2000; 95 (11): 3489-3497
The ligand for the receptor tyrosine kinase fms-like tyrosine kinase 3 (flt3), also referred to as fetal liver kinase-2 (flk-2), has an important role in hematopoiesis. The flt3 ligand (flt3L) is a growth factor for hematopoietic progenitors and induces hematopoietic progenitor and stem cell mobilization in vivo. In addition, when mice are treated with flt3L immature B cells, natural killer (NK) cells and dendritic cells (DC) are expanded in vivo. To further elucidate the role of flt3L in hematopoiesis, mice lacking flt3L (flt3L-/-) were generated by targeted gene disruption. Leukocyte cellularity was reduced in the bone marrow, peripheral blood, lymph nodes (LN), and spleen. Thymic cellularity, blood hematocrit, and platelet numbers were not affected. Significantly reduced numbers of myeloid and B-lymphoid progenitors were noted in the BM of flt3L-/- mice. In addition a marked deficiency of NK cells in the spleen was noted. DC numbers were also reduced in the spleen, LN, and thymus. Both myeloid-related (CD11c(++) CD8alpha(-)) and lymphoid-related (CD11c(++) CD8alpha(+)) DC numbers were affected. We conclude that flt3L has an important role in the expansion of early hematopoietic progenitors and in the generation of mature peripheral leukocytes.
View details for Web of Science ID 000087351600030
View details for PubMedID 10828034
Distinct dendritic cell subsets differentially regulate the class of immune response in vivo
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
1999; 96 (3): 1036-1041
Dendritic cells (DCs) are unique in their ability to stimulate T cells and initiate adaptive immunity. Injection of mice with the cytokine Flt3-ligand (FL) dramatically expands mature lymphoid and myeloid-related DC subsets. In contrast, injection of a polyethylene glycol-modified form of granulocyte/macrophage colony-stimulating factor (GM-CSF) into mice only expands the myeloid-related DC subset. These DC subsets differ in the cytokine profiles they induce in T cells in vivo. The lymphoid-related subset induces high levels of the Th1 cytokines interferon gamma and interleukin (IL)-2 but little or no Th2 cytokines. In contrast, the myeloid-related subset induces large amounts of the Th2 cytokines IL-4 and IL-10, in addition to interferon gamma and IL-2. FL- or GM-CSF-treated mice injected with soluble ovalbumin display dramatic increases in antigen-specific antibody titers, but the isotype profiles seem critically dependent on the cytokine used. Although FL treatment induces up to a 10, 000-fold increase in ovalbumin-specific IgG2a and a more modest increase in IgG1 titers, GM-CSF treatment favors a predominantly IgG1 response with little increase in IgG2a levels. These data suggest that distinct DC subsets have strikingly different influences on the type of immune response generated in vivo and may thus be targets for pharmacological intervention.
View details for Web of Science ID 000078484100044
View details for PubMedID 9927689
View details for PubMedCentralID PMC15346
Developmental pathways of dendritic cells in vivo - Distinct function, phenotype, and localization of dendritic cell subsets in FLT3 ligand-treated mice
JOURNAL OF IMMUNOLOGY
1997; 159 (5): 2222-2231
We have recently shown that Flt3 ligand administration dramatically increases dendritic cell (DC) numbers in various mouse tissues. This has enabled the identification of distinct mature DC subpopulations. These have been designated: population C (CD11c(bright) CD11b(bright)), D (CD11c(bright) CD11b(dull)), and E (CD11c(bright) CD11b(negative)) This report demonstrates that the mature DC subsets (C, D, and E) from Flt3 ligand-treated mice differ with respect to phenotype, geographic localization, and function. The myeloid Ags CD11b, F4/80, and Ly-6C are predominantly expressed by population C, but not D or E. In addition, a subset of population C-type DC expresses 33D1 and CD4. In contrast, DC within population D and E selectively express the lymphoid-related DC markers CD8alpha, DEC 205, CD1d, as well as CD23, elevated levels of CD117 (c-kit), CD24 (HSA), CD13, and CD54. Immunohistology indicates that the different DC subsets reside in distinct microenvironments, with populations D and E residing in the T cell areas of the white pulp, while DC within population C localize in the marginal zones. These DC subpopulations showed different capacities to phagocytose FITC-zymosan and to secrete IL-12 upon stimulation with Staphylococcus aureus cowan I strain + IFN-gamma + granulocyte-macrophage-CSF. Population C-type DC were more phagocytic but secreted little inducible IL-12 while population D- and E-type DC showed poor phagocytic capacity and secreted considerably higher levels of IL-12. These results underscore the importance of viewing DC development in vivo, as an interplay between distinct lineages and a maturational dependence on specific microenvironmental signals.
View details for Web of Science ID A1997XR80200021
View details for PubMedID 9278310
SOLUBLE-ANTIGEN CAN CAUSE ENHANCED APOPTOSIS OF GERMINAL-CENTER B-CELLS
1995; 375 (6529): 331-334
Germinal centres are dynamic microenvironments of B-lymphocyte differentiation, which develop in secondary lymphoid tissues during immune responses. Within germinal centres, activated B lymphocytes proliferate and point mutations are rapidly introduced into the genes encoding their immunoglobulin receptors. As a result, new specificities of B cells are created, including those with a heightened capacity to bind the immunizing antigen. Immunoglobulin gene mutation can also lead to reactivity to self antigens. It has been suggested that any newly formed self-reactive B cells are eliminated within the germinal centre in order to avoid autoimmunity. Here we present evidence that antigen-specific, high-affinity, germinal-centre B cells are rapidly killed by apoptosis in situ when they encounter soluble antigen. The effect seems to act directly on the B cells, rather than through helper T cells. Furthermore, the apoptosis is unique to germinal-centre cells, and is only incompletely impeded by constitutive expression of the proto-oncogene bcl-2. This phenomenon may reflect clonal deletion of self-reactive B cells within germinal centres.
View details for Web of Science ID A1995RA03000055
View details for PubMedID 7753199