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1.
Annu Rev Immunol ; 38: 727-757, 2020 04 26.
Article in English | MEDLINE | ID: mdl-32075461

ABSTRACT

Immune cells are characterized by diversity, specificity, plasticity, and adaptability-properties that enable them to contribute to homeostasis and respond specifically and dynamically to the many threats encountered by the body. Single-cell technologies, including the assessment of transcriptomics, genomics, and proteomics at the level of individual cells, are ideally suited to studying these properties of immune cells. In this review we discuss the benefits of adopting single-cell approaches in studying underappreciated qualities of immune cells and highlight examples where these technologies have been critical to advancing our understanding of the immune system in health and disease.


Subject(s)
Immune System/immunology , Immune System/metabolism , Immunity , Single-Cell Analysis , Animals , Biomarkers , Disease Susceptibility , Homeostasis , Humans , Immune System/cytology , Molecular Imaging , Single-Cell Analysis/methods
2.
Cell ; 181(6): 1291-1306.e19, 2020 06 11.
Article in English | MEDLINE | ID: mdl-32407674

ABSTRACT

Enteroendocrine cells (EECs) sense intestinal content and release hormones to regulate gastrointestinal activity, systemic metabolism, and food intake. Little is known about the molecular make-up of human EEC subtypes and the regulated secretion of individual hormones. Here, we describe an organoid-based platform for functional studies of human EECs. EEC formation is induced in vitro by transient expression of NEUROG3. A set of gut organoids was engineered in which the major hormones are fluorescently tagged. A single-cell mRNA atlas was generated for the different EEC subtypes, and their secreted products were recorded by mass-spectrometry. We note key differences to murine EECs, including hormones, sensory receptors, and transcription factors. Notably, several hormone-like molecules were identified. Inter-EEC communication is exemplified by secretin-induced GLP-1 secretion. Indeed, individual EEC subtypes carry receptors for various EEC hormones. This study provides a rich resource to study human EEC development and function.


Subject(s)
Enteroendocrine Cells/metabolism , RNA, Messenger/genetics , Cells, Cultured , Gastrointestinal Hormones/genetics , Gastrointestinal Tract/metabolism , Glucagon-Like Peptide 1/genetics , Humans , Organoids/metabolism , Transcription Factors/genetics , Transcriptome/genetics
3.
Nat Immunol ; 21(12): 1597-1610, 2020 12.
Article in English | MEDLINE | ID: mdl-33046889

ABSTRACT

The dynamics of CD4+ T cell memory development remain to be examined at genome scale. In malaria-endemic regions, antimalarial chemoprevention protects long after its cessation and associates with effects on CD4+ T cells. We applied single-cell RNA sequencing and computational modelling to track memory development during Plasmodium infection and treatment. In the absence of central memory precursors, two trajectories developed as T helper 1 (TH1) and follicular helper T (TFH) transcriptomes contracted and partially coalesced over three weeks. Progeny of single clones populated TH1 and TFH trajectories, and fate-mapping suggested that there was minimal lineage plasticity. Relationships between TFH and central memory were revealed, with antimalarials modulating these responses and boosting TH1 recall. Finally, single-cell epigenomics confirmed that heterogeneity among effectors was partially reset in memory. Thus, the effector-to-memory transition in CD4+ T cells is gradual during malaria and is modulated by antiparasitic drugs. Graphical user interfaces are presented for examining gene-expression dynamics and gene-gene correlations ( http://haquelab.mdhs.unimelb.edu.au/cd4_memory/ ).


Subject(s)
CD4-Positive T-Lymphocytes/immunology , CD4-Positive T-Lymphocytes/metabolism , Immunologic Memory , Malaria/immunology , Plasmodium/immunology , Transcriptome , Adoptive Transfer , Animals , Antimalarials/pharmacology , Biomarkers , Chromatin/genetics , Disease Models, Animal , Gene Expression Profiling , Humans , Malaria/parasitology , Malaria/therapy , Mice , Plasmodium/drug effects
4.
Nat Immunol ; 21(3): 343-353, 2020 03.
Article in English | MEDLINE | ID: mdl-32066951

ABSTRACT

Gastrointestinal microbiota and immune cells interact closely and display regional specificity; however, little is known about how these communities differ with location. Here, we simultaneously assess microbiota and single immune cells across the healthy, adult human colon, with paired characterization of immune cells in the mesenteric lymph nodes, to delineate colonic immune niches at steady state. We describe distinct helper T cell activation and migration profiles along the colon and characterize the transcriptional adaptation trajectory of regulatory T cells between lymphoid tissue and colon. Finally, we show increasing B cell accumulation, clonal expansion and mutational frequency from the cecum to the sigmoid colon and link this to the increasing number of reactive bacterial species.


Subject(s)
Colon/immunology , Colon/microbiology , Gastrointestinal Microbiome/immunology , Adult , B-Lymphocytes/immunology , Colon/cytology , Humans , Intestinal Mucosa/cytology , Intestinal Mucosa/immunology , Intestinal Mucosa/microbiology , Lymph Nodes/cytology , Lymph Nodes/immunology , Lymphocyte Activation , Organ Specificity , RNA-Seq , T-Lymphocytes, Helper-Inducer/immunology , T-Lymphocytes, Regulatory/immunology , Transcriptome
6.
Nature ; 597(7875): 196-205, 2021 09.
Article in English | MEDLINE | ID: mdl-34497388

ABSTRACT

The Human Developmental Cell Atlas (HDCA) initiative, which is part of the Human Cell Atlas, aims to create a comprehensive reference map of cells during development. This will be critical to understanding normal organogenesis, the effect of mutations, environmental factors and infectious agents on human development, congenital and childhood disorders, and the cellular basis of ageing, cancer and regenerative medicine. Here we outline the HDCA initiative and the challenges of mapping and modelling human development using state-of-the-art technologies to create a reference atlas across gestation. Similar to the Human Genome Project, the HDCA will integrate the output from a growing community of scientists who are mapping human development into a unified atlas. We describe the early milestones that have been achieved and the use of human stem-cell-derived cultures, organoids and animal models to inform the HDCA, especially for prenatal tissues that are hard to acquire. Finally, we provide a roadmap towards a complete atlas of human development.


Subject(s)
Cell Movement , Cell Tracking , Cells/cytology , Developmental Biology/methods , Embryo, Mammalian/cytology , Fetus/cytology , Information Dissemination , Organogenesis , Adult , Animals , Atlases as Topic , Cell Culture Techniques , Cell Survival , Data Visualization , Female , Humans , Imaging, Three-Dimensional , Male , Models, Animal , Organogenesis/genetics , Organoids/cytology , Stem Cells/cytology
7.
Nature ; 597(7875): 250-255, 2021 09.
Article in English | MEDLINE | ID: mdl-34497389

ABSTRACT

The cellular landscape of the human intestinal tract is dynamic throughout life, developing in utero and changing in response to functional requirements and environmental exposures. Here, to comprehensively map cell lineages, we use single-cell RNA sequencing and antigen receptor analysis of almost half a million cells from up to 5 anatomical regions in the developing and up to 11 distinct anatomical regions in the healthy paediatric and adult human gut. This reveals the existence of transcriptionally distinct BEST4 epithelial cells throughout the human intestinal tract. Furthermore, we implicate IgG sensing as a function of intestinal tuft cells. We describe neural cell populations in the developing enteric nervous system, and predict cell-type-specific expression of genes associated with Hirschsprung's disease. Finally, using a systems approach, we identify key cell players that drive the formation of secondary lymphoid tissue in early human development. We show that these programs are adopted in inflammatory bowel disease to recruit and retain immune cells at the site of inflammation. This catalogue of intestinal cells will provide new insights into cellular programs in development, homeostasis and disease.


Subject(s)
Aging , Enteric Nervous System/cytology , Fetus/cytology , Health , Intestines/cytology , Intestines/growth & development , Lymph Nodes/cytology , Lymph Nodes/growth & development , Adult , Animals , Child , Crohn Disease/pathology , Datasets as Topic , Enteric Nervous System/anatomy & histology , Enteric Nervous System/embryology , Enteric Nervous System/growth & development , Epithelial Cells/cytology , Female , Fetus/anatomy & histology , Fetus/embryology , Humans , Intestines/embryology , Intestines/innervation , Lymph Nodes/embryology , Lymph Nodes/pathology , Mice , Mice, Inbred C57BL , Organogenesis , Receptors, IgG/metabolism , Signal Transduction , Spatio-Temporal Analysis , Time Factors
8.
Blood ; 141(19): 2343-2358, 2023 05 11.
Article in English | MEDLINE | ID: mdl-36758207

ABSTRACT

Classic Hodgkin lymphoma (cHL) has a rich immune infiltrate, which is an intrinsic component of the neoplastic process. Malignant Hodgkin Reed-Sternberg cells (HRSCs) create an immunosuppressive microenvironment by the expression of regulatory molecules, preventing T-cell activation. It has also been demonstrated that mononuclear phagocytes (MNPs) in the vicinity of HRSCs express similar regulatory mechanisms in parallel, and their presence in tissue is associated with inferior patient outcomes. MNPs in cHL have hitherto been identified by a small number of canonical markers and are usually described as tumor-associated macrophages. The organization of MNP networks and interactions with HRSCs remains unexplored at high resolution. Here, we defined the global immune-cell composition of cHL and nonlymphoma lymph nodes, integrating data across single-cell RNA sequencing, spatial transcriptomics, and multiplexed immunofluorescence. We observed that MNPs comprise multiple subsets of monocytes, macrophages, and dendritic cells (DCs). Classical monocytes, macrophages and conventional DC2s were enriched in the vicinity of HRSCs, but plasmacytoid DCs and activated DCs were excluded. Unexpectedly, cDCs and monocytes expressed immunoregulatory checkpoints PD-L1, TIM-3, and the tryptophan-catabolizing protein IDO, at the same level as macrophages. Expression of these molecules increased with age. We also found that classical monocytes are important signaling hubs, potentially controlling the retention of cDC2 and ThExh via CCR1-, CCR4-, CCR5-, and CXCR3-dependent signaling. Enrichment of the cDC2-monocyte-macrophage network in diagnostic biopsies is associated with early treatment failure. These results reveal unanticipated complexity and spatial polarization within the MNP compartment, further demonstrating their potential roles in immune evasion by cHL.


Subject(s)
Hodgkin Disease , Humans , Hodgkin Disease/diagnosis , Reed-Sternberg Cells/metabolism , Macrophages/metabolism , Monocytes/metabolism , Immunosuppressive Agents , Tumor Microenvironment
9.
Nat Rev Genet ; 25(4): 235, 2024 Apr.
Article in English | MEDLINE | ID: mdl-38291235
10.
Gastroenterology ; 162(3): 859-876, 2022 03.
Article in English | MEDLINE | ID: mdl-34780721

ABSTRACT

BACKGROUND & AIMS: Monogenic forms of inflammatory bowel disease (IBD) illustrate the essential roles of individual genes in pathways and networks safeguarding immune tolerance and gut homeostasis. METHODS: To build a taxonomy model, we assessed 165 disorders. Genes were prioritized based on penetrance of IBD and disease phenotypes were integrated with multi-omics datasets. Monogenic IBD genes were classified by (1) overlapping syndromic features, (2) response to hematopoietic stem cell transplantation, (3) bulk RNA-sequencing of 32 tissues, (4) single-cell RNA-sequencing of >50 cell subsets from the intestine of healthy individuals and patients with IBD (pediatric and adult), and (5) proteomes of 43 immune subsets. The model was validated by addition of newly identified monogenic IBD defects. As a proof-of-concept, we explore the intersection between immunometabolism and antimicrobial activity for a group of disorders (G6PC3/SLC37A4). RESULTS: Our quantitative integrated taxonomy defines the cellular landscape of monogenic IBD gene expression across 102 genes with high and moderate penetrance (81 in the model set and 21 genes in the validation set). We illustrate distinct cellular networks, highlight expression profiles across understudied cell types (e.g., CD8+ T cells, neutrophils, epithelial subsets, and endothelial cells) and define genotype-phenotype associations (perianal disease and defective antimicrobial activity). We illustrate processes and pathways shared across cellular compartments and phenotypic groups and highlight cellular immunometabolism with mammalian target of rapamycin activation as one of the converging pathways. There is an overlap of genes and enriched cell-specific expression between monogenic and polygenic IBD. CONCLUSION: Our taxonomy integrates genetic, clinical and multi-omic data; providing a basis for genomic diagnostics and testable hypotheses for disease functions and treatment responses.


Subject(s)
Inflammatory Bowel Diseases/classification , Inflammatory Bowel Diseases/genetics , Age of Onset , Antiporters/genetics , Cells, Cultured , Classification , Gene Expression Profiling , Genetic Association Studies , Genotype , Glucose-6-Phosphatase/genetics , Glucose-6-Phosphate/metabolism , Humans , Inflammatory Bowel Diseases/metabolism , Macrophages , Metabolomics , Monosaccharide Transport Proteins/genetics , Penetrance , Phenotype , Signal Transduction/genetics
11.
J Immunol ; 204(11): 2949-2960, 2020 06 01.
Article in English | MEDLINE | ID: mdl-32321759

ABSTRACT

Despite extensive mapping of long noncoding RNAs in immune cells, their function in vivo remains poorly understood. In this study, we identify over 100 long noncoding RNAs that are differentially expressed within 24 h of Th1 cell activation. Among those, we show that suppression of Malat1 is a hallmark of CD4+ T cell activation, but its complete deletion results in more potent immune responses to infection. This is because Malat1-/- Th1 and Th2 cells express lower levels of the immunosuppressive cytokine IL-10. In vivo, the reduced CD4+ T cell IL-10 expression in Malat1-/- mice underpins enhanced immunity and pathogen clearance in experimental visceral leishmaniasis (Leishmania donovani) but more severe disease in a model of malaria (Plasmodium chabaudi chabaudi AS). Mechanistically, Malat1 regulates IL-10 through enhancing expression of Maf, a key transcriptional regulator of IL-10 Maf expression correlates with Malat1 in single Ag-specific Th cells from P. chabaudi chabaudi AS-infected mice and is downregulated in Malat1-/- Th1 and Th2 cells. The Malat1 RNA is responsible for these effects, as antisense oligonucleotide-mediated inhibition of Malat1 also suppresses Maf and IL-10 levels. Our results reveal that through promoting expression of the Maf/IL-10 axis in effector Th cells, Malat1 is a nonredundant regulator of mammalian immunity.


Subject(s)
Interleukin-10/metabolism , Leishmania donovani/physiology , Leishmaniasis, Visceral/immunology , Proto-Oncogene Proteins c-maf/metabolism , RNA, Long Noncoding/genetics , Th1 Cells/immunology , Th2 Cells/immunology , Animals , Female , Gene Expression Regulation , Humans , Immune Tolerance , Immunity/genetics , Lymphocyte Activation , Mice , Mice, Inbred C57BL , Mice, Knockout , Proto-Oncogene Proteins c-maf/genetics , Up-Regulation
12.
PLoS Pathog ; 15(2): e1007599, 2019 02.
Article in English | MEDLINE | ID: mdl-30811498

ABSTRACT

Plasmodium parasites invade and multiply inside red blood cells (RBC). Through a cycle of maturation, asexual replication, rupture and release of multiple infective merozoites, parasitised RBC (pRBC) can reach very high numbers in vivo, a process that correlates with disease severity in humans and experimental animals. Thus, controlling pRBC numbers can prevent or ameliorate malaria. In endemic regions, circulating parasite-specific antibodies associate with immunity to high parasitemia. Although in vitro assays reveal that protective antibodies could control pRBC via multiple mechanisms, in vivo assessment of antibody function remains challenging. Here, we employed two mouse models of antibody-mediated immunity to malaria, P. yoelii 17XNL and P. chabaudi chabaudi AS infection, to study infection-induced, parasite-specific antibody function in vivo. By tracking a single generation of pRBC, we tested the hypothesis that parasite-specific antibodies accelerate pRBC clearance. Though strongly protective against homologous re-challenge, parasite-specific IgG did not alter the rate of pRBC clearance, even in the presence of ongoing, systemic inflammation. Instead, antibodies prevented parasites progressing from one generation of RBC to the next. In vivo depletion studies using clodronate liposomes or cobra venom factor, suggested that optimal antibody function required splenic macrophages and dendritic cells, but not complement C3/C5-mediated killing. Finally, parasite-specific IgG bound poorly to the surface of pRBC, yet strongly to structures likely exposed by the rupture of mature schizonts. Thus, in our models of humoral immunity to malaria, infection-induced antibodies did not accelerate pRBC clearance, and instead co-operated with splenic phagocytes to block subsequent generations of pRBC.


Subject(s)
Malaria/immunology , Malaria/metabolism , Plasmodium/growth & development , Animals , Antibodies, Protozoan/metabolism , Disease Models, Animal , Erythrocytes/microbiology , Erythrocytes/physiology , Humans , Mice , Parasites , Phagocytes , Plasmodium/metabolism , Plasmodium/pathogenicity , Plasmodium chabaudi/immunology , Plasmodium chabaudi/pathogenicity , Plasmodium yoelii/immunology , Plasmodium yoelii/pathogenicity
13.
Immunol Cell Biol ; 98(6): 428-430, 2020 07.
Article in English | MEDLINE | ID: mdl-32418276

ABSTRACT

Chen et al. describe how B-cell clones observed in the gut of many different individuals (recurrent or "public" clonotypes) are shaped by the combined influences of common microbial antigens and underlying genomic recombination biases.


Subject(s)
Gastrointestinal Microbiome , B-Lymphocytes , Clone Cells , Germ Cells , Germinal Center , Humans
14.
J Immunol ; 200(4): 1443-1456, 2018 02 15.
Article in English | MEDLINE | ID: mdl-29321276

ABSTRACT

Differentiation of CD4+ Th cells is critical for immunity to malaria. Several innate immune signaling pathways have been implicated in the detection of blood-stage Plasmodium parasites, yet their influence over Th cell immunity remains unclear. In this study, we used Plasmodium-reactive TCR transgenic CD4+ T cells, termed PbTII cells, during nonlethal P. chabaudi chabaudi AS and P. yoelii 17XNL infection in mice, to examine Th cell development in vivo. We found no role for caspase1/11, stimulator of IFN genes, or mitochondrial antiviral-signaling protein, and only modest roles for MyD88 and TRIF-dependent signaling in controlling PbTII cell expansion. In contrast, IFN regulatory factor 3 (IRF3) was important for supporting PbTII expansion, promoting Th1 over T follicular helper (Tfh) differentiation, and controlling parasites during the first week of infection. IRF3 was not required for early priming by conventional dendritic cells, but was essential for promoting CXCL9 and MHC class II expression by inflammatory monocytes that supported PbTII responses in the spleen. Thereafter, IRF3-deficiency boosted Tfh responses, germinal center B cell and memory B cell development, parasite-specific Ab production, and resolution of infection. We also noted a B cell-intrinsic role for IRF3 in regulating humoral immune responses. Thus, we revealed roles for IRF3 in balancing Th1- and Tfh-dependent immunity during nonlethal infection with blood-stage Plasmodium parasites.


Subject(s)
Cell Differentiation/immunology , Interferon Regulatory Factor-3/immunology , Malaria/immunology , T-Lymphocytes, Helper-Inducer/immunology , Th1 Cells/immunology , Animals , Female , Germinal Center/immunology , Mice , Mice, Inbred C57BL , Mice, Transgenic , Spleen/immunology
15.
Proc Natl Acad Sci U S A ; 114(29): 7701-7706, 2017 07 18.
Article in English | MEDLINE | ID: mdl-28673996

ABSTRACT

Severe malaria and associated high parasite burdens occur more frequently in humans lacking robust adaptive immunity to Plasmodium falciparum Nevertheless, the host may partly control blood-stage parasite numbers while adaptive immunity is gradually established. Parasite control has typically been attributed to enhanced removal of parasites by the host, although in vivo quantification of this phenomenon remains challenging. We used a unique in vivo approach to determine the fate of a single cohort of semisynchronous, Plasmodium berghei ANKA- or Plasmodium yoelii 17XNL-parasitized red blood cells (pRBCs) after transfusion into naive or acutely infected mice. As previously shown, acutely infected mice, with ongoing splenic and systemic inflammatory responses, controlled parasite population growth more effectively than naive controls. Surprisingly, however, this was not associated with accelerated removal of pRBCs from circulation. Instead, transfused pRBCs remained in circulation longer in acutely infected mice. Flow cytometric assessment and mathematical modeling of intraerythrocytic parasite development revealed an unexpected and substantial slowing of parasite maturation in acutely infected mice, extending the life cycle from 24 h to 40 h. Importantly, impaired parasite maturation was the major contributor to control of parasite growth in acutely infected mice. Moreover, by performing the same experiments in rag1-/- mice, which lack T and B cells and mount weak inflammatory responses, we revealed that impaired parasite maturation is largely dependent upon the host response to infection. Thus, impairment of parasite maturation represents a host-mediated, immune system-dependent mechanism for limiting parasite population growth during the early stages of an acute blood-stage Plasmodium infection.


Subject(s)
Host-Parasite Interactions , Malaria, Falciparum/immunology , Malaria, Falciparum/parasitology , Plasmodium berghei/physiology , Plasmodium falciparum/physiology , Adaptive Immunity , Animals , Cytokines/metabolism , Erythrocytes/parasitology , Female , Flow Cytometry , Green Fluorescent Proteins/metabolism , Homeodomain Proteins/genetics , Immune System , Inflammation , Malaria , Mice , Mice, Inbred C57BL , Mice, Transgenic , Models, Theoretical , Plasmodium yoelii/physiology
16.
J Immunol ; 199(12): 4165-4179, 2017 12 15.
Article in English | MEDLINE | ID: mdl-29084838

ABSTRACT

We describe an MHC class II (I-Ab)-restricted TCR transgenic mouse line that produces CD4+ T cells specific for Plasmodium species. This line, termed PbT-II, was derived from a CD4+ T cell hybridoma generated to blood-stage Plasmodium berghei ANKA (PbA). PbT-II cells responded to all Plasmodium species and stages tested so far, including rodent (PbA, P. berghei NK65, Plasmodium chabaudi AS, and Plasmodium yoelii 17XNL) and human (Plasmodium falciparum) blood-stage parasites as well as irradiated PbA sporozoites. PbT-II cells can provide help for generation of Ab to P. chabaudi infection and can control this otherwise lethal infection in CD40L-deficient mice. PbT-II cells can also provide help for development of CD8+ T cell-mediated experimental cerebral malaria (ECM) during PbA infection. Using PbT-II CD4+ T cells and the previously described PbT-I CD8+ T cells, we determined the dendritic cell (DC) subsets responsible for immunity to PbA blood-stage infection. CD8+ DC (a subset of XCR1+ DC) were the major APC responsible for activation of both T cell subsets, although other DC also contributed to CD4+ T cell responses. Depletion of CD8+ DC at the beginning of infection prevented ECM development and impaired both Th1 and follicular Th cell responses; in contrast, late depletion did not affect ECM. This study describes a novel and versatile tool for examining CD4+ T cell immunity during malaria and provides evidence that CD4+ T cell help, acting via CD40L signaling, can promote immunity or pathology to blood-stage malaria largely through Ag presentation by CD8+ DC.


Subject(s)
Antigen Presentation , CD4-Positive T-Lymphocytes/immunology , CD40 Antigens/immunology , Dendritic Cells/immunology , Malaria/immunology , Mice, Transgenic/immunology , Parasitemia/immunology , T-Lymphocytes, Cytotoxic/immunology , Animals , Antigens, Protozoan/immunology , CD40 Antigens/deficiency , CD40 Ligand/immunology , Cells, Cultured , Crosses, Genetic , Hybridomas , Lymphocyte Activation , Malaria, Cerebral/immunology , Malaria, Cerebral/prevention & control , Mice, Inbred BALB C , Mice, Inbred C57BL , Mice, Transgenic/genetics , Plasmodium berghei/immunology , Radiation Chimera
17.
PLoS Pathog ; 12(11): e1005999, 2016 Nov.
Article in English | MEDLINE | ID: mdl-27812214

ABSTRACT

Parasite-specific antibodies protect against blood-stage Plasmodium infection. However, in malaria-endemic regions, it takes many months for naturally-exposed individuals to develop robust humoral immunity. Explanations for this have focused on antigenic variation by Plasmodium, but have considered less whether host production of parasite-specific antibody is sub-optimal. In particular, it is unclear whether host immune factors might limit antibody responses. Here, we explored the effect of Type I Interferon signalling via IFNAR1 on CD4+ T-cell and B-cell responses in two non-lethal murine models of malaria, P. chabaudi chabaudi AS (PcAS) and P. yoelii 17XNL (Py17XNL) infection. Firstly, we demonstrated that CD4+ T-cells and ICOS-signalling were crucial for generating germinal centre (GC) B-cells, plasmablasts and parasite-specific antibodies, and likewise that T follicular helper (Tfh) cell responses relied on B cells. Next, we found that IFNAR1-signalling impeded the resolution of non-lethal blood-stage infection, which was associated with impaired production of parasite-specific IgM and several IgG sub-classes. Consistent with this, GC B-cell formation, Ig-class switching, plasmablast and Tfh differentiation were all impaired by IFNAR1-signalling. IFNAR1-signalling proceeded via conventional dendritic cells, and acted early by limiting activation, proliferation and ICOS expression by CD4+ T-cells, by restricting the localization of activated CD4+ T-cells adjacent to and within B-cell areas of the spleen, and by simultaneously suppressing Th1 and Tfh responses. Finally, IFNAR1-deficiency accelerated humoral immune responses and parasite control by boosting ICOS-signalling. Thus, we provide evidence of a host innate cytokine response that impedes the onset of humoral immunity during experimental malaria.


Subject(s)
Antibodies, Protozoan/immunology , Immunity, Humoral/immunology , Inducible T-Cell Co-Stimulator Protein/immunology , Malaria/immunology , Receptor, Interferon alpha-beta/immunology , Animals , B-Lymphocytes/immunology , CD4-Positive T-Lymphocytes/immunology , Disease Models, Animal , Enzyme-Linked Immunosorbent Assay , Female , Flow Cytometry , Lymphocyte Activation/immunology , Mice , Mice, Inbred C57BL , Mice, Knockout , Microscopy, Confocal , Plasmodium chabaudi/immunology , Plasmodium yoelii/immunology , Signal Transduction/immunology
18.
Eur J Immunol ; 45(1): 130-41, 2015 Jan.
Article in English | MEDLINE | ID: mdl-25319247

ABSTRACT

Type I IFN signaling suppresses splenic T helper 1 (Th1) responses during blood-stage Plasmodium berghei ANKA (PbA) infection in mice, and is crucial for mediating tissue accumulation of parasites and fatal cerebral symptoms via mechanisms that remain to be fully characterized. Interferon regulatory factor 7 (IRF7) is considered to be a master regulator of type I IFN responses. Here, we assessed IRF7 for its roles during lethal PbA infection and nonlethal Plasmodium chabaudi chabaudi AS (PcAS) infection as two distinct models of blood-stage malaria. We found that IRF7 was not essential for tissue accumulation of parasites, cerebral symptoms, or brain pathology. Using timed administration of anti-IFNAR1 mAb, we show that late IFNAR1 signaling promotes fatal disease via IRF7-independent mechanisms. Despite this, IRF7 significantly impaired early splenic Th1 responses and limited control of parasitemia during PbA infection.  Finally, IRF7 also suppressed antiparasitic immunity and Th1 responses during nonlethal PcAS infection. Together, our data support a model in which IRF7 suppresses antiparasitic immunity in the spleen, while IFNAR1-mediated, but IRF7-independent, signaling contributes to pathology in the brain during experimental blood-stage malaria.


Subject(s)
Brain/immunology , Interferon Regulatory Factor-7/immunology , Malaria, Cerebral/immunology , Receptor, Interferon alpha-beta/immunology , Spleen/immunology , Th1 Cells/immunology , Animals , Antibodies, Monoclonal/pharmacology , Brain/drug effects , Brain/parasitology , Disease Susceptibility , Erythrocytes/parasitology , Female , Gene Expression Regulation , Host-Parasite Interactions , Interferon Regulatory Factor-7/genetics , Malaria, Cerebral/parasitology , Mice , Mice, Inbred C57BL , Plasmodium berghei/immunology , Plasmodium chabaudi/immunology , Receptor, Interferon alpha-beta/antagonists & inhibitors , Receptor, Interferon alpha-beta/genetics , Signal Transduction , Spleen/drug effects , Spleen/parasitology , Th1 Cells/parasitology , Time Factors
19.
J Immunol ; 192(8): 3709-18, 2014 Apr 15.
Article in English | MEDLINE | ID: mdl-24634490

ABSTRACT

Organ-specific immunity is a feature of many infectious diseases, including visceral leishmaniasis caused by Leishmania donovani. Experimental visceral leishmaniasis in genetically susceptible mice is characterized by an acute, resolving infection in the liver and chronic infection in the spleen. CD4+ T cell responses are critical for the establishment and maintenance of hepatic immunity in this disease model, but their role in chronically infected spleens remains unclear. In this study, we show that dendritic cells are critical for CD4+ T cell activation and expansion in all tissue sites examined. We found that FTY720-mediated blockade of T cell trafficking early in infection prevented Ag-specific CD4+ T cells from appearing in lymph nodes, but not the spleen and liver, suggesting that early CD4+ T cell priming does not occur in liver-draining lymph nodes. Extended treatment with FTY720 over the first month of infection increased parasite burdens, although this associated with blockade of lymphocyte egress from secondary lymphoid tissue, as well as with more generalized splenic lymphopenia. Importantly, we demonstrate that CD4+ T cells are required for the establishment and maintenance of antiparasitic immunity in the liver, as well as for immune surveillance and suppression of parasite outgrowth in chronically infected spleens. Finally, although early CD4+ T cell priming appeared to occur most effectively in the spleen, we unexpectedly revealed that protective CD4+ T cell-mediated hepatic immunity could be generated in the complete absence of all secondary lymphoid tissues.


Subject(s)
CD4-Positive T-Lymphocytes/immunology , Immunologic Memory , Leishmania donovani/immunology , Leishmaniasis, Visceral/immunology , Animals , Antigens, Protozoan/immunology , CD4-Positive T-Lymphocytes/drug effects , Dendritic Cells/immunology , Epitopes, T-Lymphocyte/immunology , Female , Fingolimod Hydrochloride , Immunosuppressive Agents/pharmacology , Liver/drug effects , Liver/immunology , Liver/parasitology , Lymphocyte Activation/immunology , Lymphoid Tissue/drug effects , Lymphoid Tissue/immunology , Lymphoid Tissue/parasitology , Mice , Mice, Knockout , Propylene Glycols/pharmacology , Sphingosine/analogs & derivatives , Sphingosine/pharmacology , Spleen/drug effects , Spleen/immunology , Spleen/parasitology
20.
Infect Immun ; 82(1): 212-20, 2014 Jan.
Article in English | MEDLINE | ID: mdl-24144725

ABSTRACT

Parasite biomass and microvasculature obstruction are strongly associated with disease severity and death in Plasmodium falciparum-infected humans. This is related to sequestration of mature, blood-stage parasites (schizonts) in peripheral tissue. The prevailing view is that schizont sequestration leads to an increase in pathogen biomass, yet direct experimental data to support this are lacking. Here, we first studied parasite population dynamics in inbred wild-type (WT) mice infected with the rodent species of malaria, Plasmodium berghei ANKA. As is commonly reported, these mice became moribund due to large numbers of parasites in multiple tissues. We then studied infection dynamics in a genetically targeted line of mice, which displayed minimal tissue accumulation of parasites. We constructed a mathematical model of parasite biomass dynamics, incorporating schizont-specific host clearance, both with and without schizont sequestration. Combined use of mathematical and in vivo modeling indicated, first, that the slowing of parasite growth in the genetically targeted mice can be attributed to specific clearance of schizonts from the circulation and, second, that persistent parasite growth in WT mice can be explained solely as a result of schizont sequestration. Our work provides evidence that schizont sequestration could be a major biological process driving rapid, early increases in parasite biomass during blood-stage Plasmodium infection.


Subject(s)
Biomass , Erythrocytes/parasitology , Malaria/parasitology , Models, Biological , Plasmodium berghei/growth & development , Animals , Cytokines/metabolism , Disease Models, Animal , Erythrocytes/metabolism , Female , Flow Cytometry , Luminescent Measurements , Malaria/blood , Mice , Mice, Inbred C57BL , Plasmodium berghei/pathogenicity , Schizonts/parasitology
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