207 results on '"A. K. Pierce"'
Search Results
2. From zero to sixty and back to zero again: the metabolic life of B cells
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Susan K. Pierce and Munir Akkaya
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0301 basic medicine ,Cellular differentiation ,Immunology ,Immunoglobulins ,Lymphocyte Activation ,Article ,03 medical and health sciences ,0302 clinical medicine ,Animals ,Humans ,Immunology and Allergy ,Antigens ,Cell Proliferation ,Genome stability ,Gene Rearrangement ,B-Lymphocytes ,Chemistry ,Precursor Cells, B-Lymphoid ,Cell Differentiation ,Gene rearrangement ,Cell biology ,030104 developmental biology ,Antibody Formation ,Lymphocyte activation ,Metabolic activity ,human activities ,Antibody formation ,Signal Transduction ,030215 immunology - Abstract
Throughout their lifetimes B cells shift metabolic gears to move rapidly from quiescent states to full out proliferative expansion and back again. Here we discuss recent findings that shed light on how B cells rapidly shift gears to metabolically fuel expansion and then just as rapidly down shift during phases of receptor rearrangements to ensure genome stability. We also discuss the link between metabolic activity and fate decisions in B cells.
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- 2019
3. CYP2J19 mediates carotenoid colour introgression across a natural avian hybrid zone
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Sophia C. Hayes, Daniel K Pierce, Ara Monadjem, Sifiso M. Lukhele, Michaella Moysi, Alan Brelsford, Emmanuel C. Nwankwo, Alexander N. G. Kirschel, and Bridget O. Ogolowa
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0106 biological sciences ,0301 basic medicine ,Male ,Candidate gene ,Introgression ,Color ,Locus (genetics) ,Biology ,010603 evolutionary biology ,01 natural sciences ,Africa, Southern ,Birds ,03 medical and health sciences ,Hybrid zone ,Genetics ,Animals ,Ecology, Evolution, Behavior and Systematics ,Pigmentation ,Reproductive isolation ,Phenotypic trait ,Carotenoids ,030104 developmental biology ,Evolutionary biology ,Feather ,visual_art ,Backcrossing ,visual_art.visual_art_medium ,Female ,Genome-Wide Association Study - Abstract
It has long been of interest to identify the phenotypic traits that mediate reproductive isolation between related species, and more recently, the genes that underpin them. Much work has focused on identifying genes associated with animal colour, with the candidate gene CYP2J19 identified in laboratory studies as the ketolase converting yellow dietary carotenoids to red ketocarotenoids in birds with red pigments. However, evidence that CYP2J19 explains variation between red and yellow feather coloration in wild populations of birds is lacking. Hybrid zones provide the opportunity to identify genes associated with specific traits. Here we investigate genomic regions associated with colour in red-fronted and yellow-fronted tinkerbirds across a hybrid zone in southern Africa. We sampled 85 individuals, measuring spectral reflectance of forecrown feathers and scoring colours from photographs, while testing for carotenoid presence with Raman spectroscopy. We performed a genome-wide association study to identify associations with carotenoid-based coloration, using double-digest RAD sequencing aligned to a short-read whole genome of a Pogoniulus tinkerbird. Admixture mapping using 104,933 single nucleotide polymorphisms (SNPs) identified a region of chromosome 8 that includes CYP2J19 as the only locus with more than two SNPs significantly associated with both crown hue and crown score, while Raman spectra provided evidence of ketocarotenoids in red feathers. Asymmetric backcrossing in the hybrid zone suggests that yellow-fronted females mate more often with red-fronted males than vice versa. Female red-fronted tinkerbirds mating assortatively with red-crowned males is consistent with the hypothesis that converted carotenoids are an honest signal of quality.
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- 2020
4. Testing the impact of a single nucleotide polymorphism in a Plasmodium berghei ApiAP2 transcription factor on experimental cerebral malaria in mice
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Louis H. Miller, Susan K. Pierce, Mirna Pena, Takele Yazew, Chen Feng Qi, Thomas D. Otto, Patrick W. Sheehan, Munir Akkaya, Abhisheka Bansal, Oliver Billker, and Clare K. Cimperman
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0301 basic medicine ,Parasitic infection ,Plasmodium berghei ,Virulence Factors ,Cell- och molekylärbiologi ,Malaria, Cerebral ,Protozoan Proteins ,lcsh:Medicine ,Single-nucleotide polymorphism ,Polymorphism, Single Nucleotide ,Plasmodium ,Article ,Mice ,03 medical and health sciences ,0302 clinical medicine ,parasitic diseases ,Parasite immune evasion ,Parasite genetics ,Animals ,SNP ,lcsh:Science ,Transcription factor ,Gene ,Genetics ,Multidisciplinary ,biology ,lcsh:R ,Parasite genomics ,biology.organism_classification ,Phenotype ,Extracellular Matrix ,Mice, Inbred C57BL ,030104 developmental biology ,Cerebral Malaria ,Female ,lcsh:Q ,CRISPR-Cas Systems ,030217 neurology & neurosurgery ,Cell and Molecular Biology ,Parasite host response - Abstract
Cerebral malaria (CM) is the deadliest form of severe Plasmodium infections. Currently, we have limited understanding of the mechanisms by which Plasmodium parasites induce CM. The mouse model of CM, experimental CM (ECM), induced by infection with the rodent parasite, Plasmodium berghei ANKA (PbANKA) has been extensively used to study the pathophysiology of CM. Recent genomic analyses revealed that the coding regions of PbANKA and the closely related Plasmodium berghei NK65 (PbNK65), that does not cause ECM, differ in only 21 single nucleotide polymorphysims (SNPs). Thus, the SNP-containing genes might contribute to the pathogenesis of ECM. Although the majority of these SNPs are located in genes of unknown function, one SNP is located in the DNA binding site of a member of the Plasmodium ApiAP2 transcription factor family, that we recently showed functions as a virulence factor alternating the host’s immune response to the parasite. Here, we investigated the impact of this SNP on the development of ECM. Our results using CRISPR-Cas9 engineered parasites indicate that despite its immune modulatory function, the SNP is neither necessary nor sufficient to induce ECM and thus cannot account for parasite strain-specific differences in ECM phenotypes.
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- 2020
5. A single-nucleotide polymorphism in a Plasmodium berghei ApiAP2 transcription factor alters the development of host immunity
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Patrick W. Sheehan, Takele Yazew, Chen Feng Qi, Munir Akkaya, Oliver Billker, Lindsey M. Orchard, Abhisheka Bansal, Louis H. Miller, Susan K. Pierce, Girija Thiruvengadam, Clare K. Cimperman, Philipp Ross, Mirna Pena, Manuel Llinás, Thomas D. Otto, Alvaro Molina-Cruz, Sarah L. Anzick, and Daniel E. Sturdevant
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Plasmodium berghei ,Cell- och molekylärbiologi ,Immunology ,Biology ,Adaptive Immunity ,Polymorphism, Single Nucleotide ,Host-Parasite Interactions ,03 medical and health sciences ,0302 clinical medicine ,Immune system ,Interferon ,Immunity ,parasitic diseases ,medicine ,Animals ,Protein Interaction Domains and Motifs ,Research Articles ,030304 developmental biology ,0303 health sciences ,Multidisciplinary ,Germinal center ,SciAdv r-articles ,T helper cell ,biochemical phenomena, metabolism, and nutrition ,Th1 Cells ,Acquired immune system ,biology.organism_classification ,Virology ,3. Good health ,Malaria ,DNA-Binding Proteins ,medicine.anatomical_structure ,Culicidae ,Transcription Factor AP-2 ,biology.protein ,Antibody ,030217 neurology & neurosurgery ,Cell and Molecular Biology ,medicine.drug ,Research Article - Abstract
ApiAP2 transcription factor PBANKA_011210 is a novel Plasmodium virulence factor that blocks induction of host’s immune response., The acquisition of malaria immunity is both remarkably slow and unpredictable. At present, we know little about the malaria parasite genes that influence the host’s ability to mount a protective immune response. Here, we show that a single-nucleotide polymorphism (SNP) resulting in a single amino acid change (S to F) in an ApiAP2 transcription factor in the rodent malaria parasite Plasmodium berghei (Pb) NK65 allowed infected mice to mount a T helper cell 1 (TH1)–type immune response that controlled subsequent infections. As compared to PbNK65S, PbNK65F parasites differentially expressed 46 genes, most of which are predicted to play roles in immune evasion. PbNK65F infections resulted in an early interferon-γ response and a later expansion of germinal centers, resulting in high levels of infected red blood cell–specific TH1-type immunoglobulin G2b (IgG2b) and IgG2c antibodies. Thus, the Pb ApiAP2 transcription factor functions as a critical parasite virulence factor in malaria infections.
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- 2020
6. Toll-like receptor 9 antagonizes antibody affinity maturation
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Haewon Sohn, Jeff Skinner, Brandon P. Theall, Mirna Pena, Alexander S. Roesler, Juraj Kabat, Pietro Miozzo, Susan K. Pierce, Jinghua Lu, Ann S. Kim, David W. Dorward, Billur Akkaya, Eric Dahlstrom, Louis H. Miller, Munir Akkaya, and Travis Henke
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0301 basic medicine ,Immunology ,Antigen presentation ,Antibody Affinity ,Lymphocyte Activation ,Article ,Affinity maturation ,Mice ,03 medical and health sciences ,0302 clinical medicine ,Antigen ,Malaria Vaccines ,medicine ,Animals ,Humans ,Immunology and Allergy ,Receptor ,B cell ,Antigen Presentation ,biology ,Chemistry ,Antibody titer ,TLR9 ,Germinal Center ,Cell biology ,030104 developmental biology ,medicine.anatomical_structure ,Toll-Like Receptor 9 ,Antibody Formation ,biology.protein ,Antibody ,030215 immunology - Abstract
Key events in T cell–dependent antibody responses, including affinity maturation, are dependent on the B cell’s presentation of antigen to helper T cells at critical checkpoints in germinal-center formation in secondary lymphoid organs. Here we found that signaling via Toll-like receptor 9 (TLR9) blocked the ability of antigen-specific B cells to capture, process and present antigen and to activate antigen-specific helper T cells in vitro. In a mouse model in vivo and in a human clinical trial, the TLR9 agonist CpG enhanced the magnitude of the antibody response to a protein vaccine but failed to promote affinity maturation. Thus, TLR9 signaling might enhance antibody titers at the expense of the ability of B cells to engage in germinal-center events that are highly dependent on B cells’ capture and presentation of antigen. The presentation of antigen by germinal-center B cells to follicular T cells engenders the process of antibody affinity maturation and humoral memory. Pierce and colleagues show that TLR9 signaling in B cells antagonizes B cell–mediated antigen presentation, which leads to the enhanced generation of short-lived plasma cells and the production of lower-affinity antibodies.
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- 2018
7. B Cells Produce Type 1 IFNs in Response to the TLR9 Agonist CpG-A Conjugated to Cationic Lipids
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Mirna Pena, Susan K. Pierce, Pietro Miozzo, Billur Akkaya, Akanksha Chaturvedi, Olena Kamenyeva, Juraj Kabat, Patrick W. Sheehan, Munir Akkaya, Mukul Rawat, Ann S. Kim, and Silvia Bolland
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0301 basic medicine ,Immunology ,Biology ,Lymphocyte Activation ,Article ,Proinflammatory cytokine ,Mice ,03 medical and health sciences ,Immunity ,Cations ,medicine ,Animals ,Immunologic Factors ,Immunology and Allergy ,Receptor ,B cell ,B-Lymphocytes ,Innate immune system ,Interleukin-6 ,TLR9 ,Acquired immune system ,Lipids ,Immunity, Innate ,Cell biology ,B-1 cell ,030104 developmental biology ,medicine.anatomical_structure ,Oligodeoxyribonucleotides ,Toll-Like Receptor 9 ,Antibody Formation ,Interferon Type I ,Cytokines - Abstract
B cells express the innate receptor, TLR9, which signals in response to unmethylated CpG sequences in microbial DNA. Of the two major classes of CpG-containing oligonucleotides, CpG-A appears restricted to inducing type 1 IFN in innate immune cells and CpG-B to activating B cells to proliferate and produce Abs and inflammatory cytokines. Although CpGs are candidates for adjuvants to boost innate and adaptive immunity, our understanding of the effect of CpG-A and CpG-B on B cell responses is incomplete. In this study we show that both CpG-B and CpG-A activated B cells in vitro to proliferate, secrete Abs and IL-6, and that neither CpG-B nor CpG-A alone induced type 1 IFN production. However, when incorporated into the cationic lipid, DOTAP, CpG-A, but not CpG-B, induced a type 1 IFN response in B cells in vitro and in vivo. We provide evidence that differences in the function of CpG-A and CpG-B may be related to their intracellular trafficking in B cells. These findings fill an important gap in our understanding of the B cell response to CpGs, with implications for the use of CpG-A and CpG-B as immunomodulators.
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- 2017
8. A Preliminary Molecular and Phylogenetic Analysis of the Genome of a Novel Endogenous Retrovirus in the Sea SlugElysia chlorotica
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Steven E. Massey, Padmanabhan Mahadevan, Sidney K. Pierce, and Michael L. Middlebrooks
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0301 basic medicine ,animal structures ,viruses ,Gastropoda ,Endogenous retrovirus ,Retrotransposon ,Genome, Viral ,Genome ,Virus ,03 medical and health sciences ,Phylogenetics ,Animals ,Phylogeny ,Genetics ,Base Sequence ,Phylogenetic tree ,biology ,Endogenous Retroviruses ,fungi ,Genomics ,biology.organism_classification ,Sea slug ,030104 developmental biology ,embryonic structures ,Elysia chlorotica ,General Agricultural and Biological Sciences - Abstract
An endogenous retrovirus that is present in the sea slug Elysia chlorotica is expressed in all individuals at the end of the annual life cycle. But the precise role of the virus, if any, in slug senescence or death is unknown. We have determined the genomic sequence of the virus and performed a phylogenetic analysis of the data. The 6060-base pair genome of the virus possesses a reverse transcriptase-domain-containing protein that shows similarity to retrotransposon sequences found in Aplysia californica and Strongylocentrotus purpuratus. However, nucleotide BLAST analysis of the whole genome resulted in hits to only a few portions of the genome, indicating that the Elysia chlorotica retrovirus is novel, has not been previously sequenced, and does not have great genetic similarity to other known viral species. When more invertebrate retroviral genomes are examined, a more precise phylogenetic placement of the Elysia chlorotica retrovirus can be determined.
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- 2016
9. Overexpression of an antioxidant enzyme improves male mating performance after stress in a lek-mating fruit fly
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Bailey K. Pierce, Daniel A. Hahn, Marc F. Schetelig, Alfred M. Handler, Vanessa Simões Dias, and Nicholas M. Teets
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0106 biological sciences ,Male ,Development and Physiology ,Antioxidant ,media_common.quotation_subject ,medicine.medical_treatment ,Zoology ,Biology ,010603 evolutionary biology ,01 natural sciences ,General Biochemistry, Genetics and Molecular Biology ,Antioxidants ,Courtship ,Animals, Genetically Modified ,03 medical and health sciences ,Sexual Behavior, Animal ,Lek mating ,medicine ,Animals ,Mating ,030304 developmental biology ,General Environmental Science ,media_common ,chemistry.chemical_classification ,0303 health sciences ,General Immunology and Microbiology ,Superoxide Dismutase ,fungi ,Tephritidae ,General Medicine ,Mating Preference, Animal ,Oxidative Stress ,Enzyme ,chemistry ,Female ,General Agricultural and Biological Sciences ,Reactive Oxygen Species - Abstract
In many species, courtship displays are reliable signals of male quality, and current hypotheses suggest that these displays allow females to choose males with high cellular function. Environmental stressors generate excess reactive oxygen species (ROS) that impair cellular function, and thus antioxidant pathways that remove ROS are probably critical for preserving complex sexual behaviours. Here, we test the hypothesis that enhanced antioxidant activity in mitochondria preserves mating performance following oxidative stress. Using a transgenic approach, we directly manipulated mitochondrial antioxidant activity in the Caribbean fruit fly,Anastrepha suspensa,a lek-mating species with elaborate sexual displays and intense sexual selection that is also a model for sterile insect technique programmes. We generated seven transgenic lines that overexpress mitochondrial superoxide dismutase (MnSOD). Radiation is a severe oxidative stressor used to induce sterility for sterile insect programmes. After radiation treatment, two lines with intermediate MnSOD overexpression showed enhanced mating performance relative to wild-type males. These improvements in mating corresponded with reduced oxidative damage to lipids, demonstrating that MnSOD overexpression protects flies from oxidative stress at the cellular level. For lines with improved mating performance, overexpression also preserved locomotor activity, as indicated by a laboratory climbing assay. Our results show a clear link between oxidative stress, antioxidant capacity and male performance. Our work has implications for fundamentally understanding the role of antioxidants in sexual selection, and shows promise for using transgenic approaches to enhance the field performance of insects released for area-wide pest management strategies and improving performance of biological control agents in general.
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- 2019
10. Algal Sources of Sequestered Chloroplasts in the Sacoglossan Sea Slug Elysia crispata Vary by Location and Ecotype
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Nicholas E. Curtis, Michael L. Middlebrooks, and Sidney K. Pierce
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0106 biological sciences ,0301 basic medicine ,Chloroplasts ,biology ,Ecotype ,Coral ,Gastropoda ,Sequence Analysis, DNA ,biology.organism_classification ,01 natural sciences ,Elysia crispata ,Sea slug ,Diet ,Chloroplast ,03 medical and health sciences ,030104 developmental biology ,Caribbean Region ,Chlorophyta ,Botany ,Animals ,Green algae ,Photosynthesis ,General Agricultural and Biological Sciences ,Ecosystem ,010606 plant biology & botany - Abstract
Sacoglossan sea slugs feed by suctorially consuming siphonaceous green algae. Most sacoglossan species are feeding specialists, but the Caribbean coral reef-dwelling Elysia crispata is polyphagous and sequesters chloroplasts from multiple algal species into cells lining its digestive diverticulum for use in photosynthesis. We have used sequences of the chloroplast-encoded rbcL gene to compare the chloroplast donor algae in five populations of E. crispata from various Caribbean locations. We found that E. crispata utilizes more algal species than was previously known, including some algae previously not reported as present in the region. In addition, slugs from each location had unique chloroplast arrays with little overlap, except that all locations had slugs feeding on algae within the genus Bryopsis. This variation in diet between locations suggests that the slugs may be exhibiting local adaptation in their dietary choices, and it highlights ecological differences between the Caribbean-wide reef-dwelling ecotypes and the mangrove lagoon ecotypes found in the Florida Keys.
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- 2019
11. A draft genome assembly of the solar-powered sea slug Elysia chlorotica
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Mingji Feng, Nicholas E. Curtis, Sidney K. Pierce, Mitsuyasu Hasebe, Shuai Cheng Li, Tomoaki Nishiyama, Taro Maeda, Xiaodong Fang, Nina Lundholm, Julie A. Schwartz, Qiye Li, Tomoko Shibata, Shuji Shigenobu, Ji Li, Jian Wang, Andreas Altenburger, Huimin Cai, and Huanming Yang
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Statistics and Probability ,Data Descriptor ,010504 meteorology & atmospheric sciences ,Evolution ,Gastropoda ,Sequence assembly ,Genomics ,Biology ,Library and Information Sciences ,01 natural sciences ,Genome ,DNA sequencing ,Education ,03 medical and health sciences ,Animals ,Photosynthesis ,Gene ,030304 developmental biology ,0105 earth and related environmental sciences ,Marine biology ,0303 health sciences ,Molecular Sequence Annotation ,biology.organism_classification ,Sea slug ,Computer Science Applications ,Evolutionary biology ,Elysia chlorotica ,Statistics, Probability and Uncertainty ,Information Systems - Abstract
Elysia chlorotica, a sacoglossan sea slug found off the East Coast of the United States, is well-known for its ability to sequester chloroplasts from its algal prey and survive by photosynthesis for up to 12 months in the absence of food supply. Here we present a draft genome assembly of E. chlorotica that was generated using a hybrid assembly strategy with Illumina short reads and PacBio long reads. The genome assembly comprised 9,989 scaffolds, with a total length of 557 Mb and a scaffold N50 of 442 kb. BUSCO assessment indicated that 93.3% of the expected metazoan genes were completely present in the genome assembly. Annotation of the E. chlorotica genome assembly identified 176 Mb (32.6%) of repetitive sequences and a total of 24,980 protein-coding genes. We anticipate that the annotated draft genome assembly of the E. chlorotica sea slug will promote the investigation of sacoglossan genetics, evolution, and particularly, the genetic signatures accounting for the long-term functioning of algal chloroplasts in an animal. Machine-accessible metadata file describing the reported data (ISA-Tab format)
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- 2019
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12. MRI demonstrates glutamine antagonist-mediated reversal of cerebral malaria pathology in mice
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Susan K. Pierce, Louis H. Miller, Jeeva Munasinghe, Sanhita Sinharay, William Schreiber-Stainthorp, Eva Prchalova, Jonathan D. Powell, Dragan Maric, Dima A. Hammoud, Barbara S. Slusher, and Brittany A. Riggle
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Adult ,0301 basic medicine ,Pathology ,medicine.medical_specialty ,Glutamine ,Diazooxonorleucine ,Plasmodium falciparum ,Malaria, Cerebral ,Brain Edema ,Antimalarials ,Mice ,03 medical and health sciences ,In vivo ,Edema ,medicine ,Animals ,Humans ,Malaria, Falciparum ,Child ,Multidisciplinary ,biology ,business.industry ,Antagonist ,Brain ,biology.organism_classification ,Magnetic Resonance Imaging ,Mice, Inbred C57BL ,Disease Models, Animal ,030104 developmental biology ,PNAS Plus ,Blood-Brain Barrier ,Cerebral Malaria ,Adjunctive treatment ,Disease Progression ,Female ,medicine.symptom ,Complication ,business ,Biomarkers - Abstract
The deadliest complication of Plasmodium falciparum infection is cerebral malaria (CM), with a case fatality rate of 15 to 25% in African children despite effective antimalarial chemotherapy. No adjunctive treatments are yet available for this devastating disease. We previously reported that the glutamine antagonist 6-diazo-5-oxo-l-norleucine (DON) rescued mice from experimental CM (ECM) when administered late in the infection, a time by which mice had already suffered blood–brain barrier (BBB) dysfunction, brain swelling, and hemorrhaging. Herein, we used longitudinal MR imaging to visualize brain pathology in ECM and the impact of a new DON prodrug, JHU-083, on disease progression in mice. We demonstrate in vivo the reversal of disease markers in symptomatic, infected mice following treatment, including the resolution of edema and BBB disruption, findings usually associated with a fatal outcome in children and adults with CM. Our results support the premise that JHU-083 is a potential adjunctive treatment that could rescue children and adults from fatal CM.
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- 2018
13. A Simple, Versatile Antibody-Based Barcoding Method for Flow Cytometry
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Pietro Miozzo, Munir Akkaya, Amanda H. Holstein, Ethan M. Shevach, Susan K. Pierce, and Billur Akkaya
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0301 basic medicine ,Electronic Data Processing ,Staining and Labeling ,medicine.diagnostic_test ,Immunology ,Computational biology ,Biology ,Flow Cytometry ,Molecular biology ,Antibodies ,Article ,Flow cytometry ,Mice ,03 medical and health sciences ,030104 developmental biology ,0302 clinical medicine ,medicine ,Animals ,Humans ,Immunology and Allergy ,Fluorescent Dyes ,030215 immunology - Abstract
Barcoding of biological samples is a commonly used strategy to mark or identify individuals within a complex mixture. However, cell barcoding has not yet found wide use in flow cytometry that would benefit greatly from the ability to analyze pooled experimental samples simultaneously. This is due, in part, to technical and practical limitations of current fluorescent dye-based methods. In this study, we describe a simple, versatile barcoding strategy that relies on combinations of a single Ab conjugated to different fluorochromes and thus in principle can be integrated into any flow cytometry application. To demonstrate the efficacy of the approach, we describe the results of a variety of experiments using live cells as well as fixed and permeabilized cells. The results of these studies show that Ab-based barcoding provides a simple, practical method for identifying cells from individual samples pooled for analysis by flow cytometry that has broad applications in immunological research.
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- 2016
14. Multiple Weak Linear Motifs Enhance Recruitment and Processivity in SPOP-Mediated Substrate Ubiquitination
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Christy R. Grace, Jihun Lee, Junmin Peng, Melissa R. Marzahn, Amanda Nourse, Tanja Mittag, Edmond R. Watson, Anthony A. High, Wendy K. Pierce, and Brenda A. Schulman
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0301 basic medicine ,Ubiquitin-Protein Ligases ,Amino Acid Motifs ,Plasma protein binding ,SPOP ,Article ,03 medical and health sciences ,NMR spectroscopy ,Ubiquitin ,Structural Biology ,cancer ,Animals ,Short linear motif ,Speckle-type POZ protein ,Molecular Biology ,chemistry.chemical_classification ,DNA ligase ,biology ,Ubiquitination ,Processivity ,multivalency ,degron ,Ubiquitin ligase ,Cell biology ,030104 developmental biology ,Biochemistry ,chemistry ,Hedgehogs ,biology.protein ,Degron ,Protein Binding ,Transcription Factors - Abstract
Primary sequence motifs, with millimolar affinities for binding partners, are abundant in disordered protein regions. In multivalent interactions, such weak linear motifs can cooperate to recruit binding partners via avidity effects. If linear motifs recruit modifying enzymes, optimal placement of weak motifs may regulate access to modification sites. Weak motifs may thus exert physiological relevance stronger than that suggested by their affinities, but molecular mechanisms of their function are still poorly understood. Herein, we use the N-terminal disordered region of the Hedgehog transcriptional regulator Gli3 (Gli31-90) to determine the role of weak motifs encoded in its primary sequence for the recruitment of its ubiquitin ligase CRL3SPOP and the subsequent effect on ubiquitination efficiency. The substrate adaptor SPOP binds linear motifs through its MATH (meprin and TRAF homology) domain and forms higher-order oligomers through its oligomerization domains, rendering SPOP multivalent for its substrates. Gli3 has multiple weak SPOP binding motifs. We map three such motifs in Gli31-90, the weakest of which has a millimolar dissociation constant. Multivalency of ligase and substrate for each other facilitates enhanced ligase recruitment and stimulates Gli31-90 ubiquitination in in vitro ubiquitination assays. We speculate that the weak motifs enable processivity through avidity effects and by providing steric access to lysine residues that are otherwise not prioritized for polyubiquitination. Weak motifs may generally be employed in multivalent systems to act as gatekeepers regulating post-translational modification.
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- 2016
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15. Increased Mitochondrial Biogenesis and Reactive Oxygen Species Production Accompany Prolonged CD4
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Billur, Akkaya, Alexander S, Roesler, Pietro, Miozzo, Brandon P, Theall, Jafar, Al Souz, Margery G, Smelkinson, Juraj, Kabat, Javier, Traba, Michael N, Sack, Joseph A, Brzostowski, Mirna, Pena, David W, Dorward, Susan K, Pierce, and Munir, Akkaya
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CD4-Positive T-Lymphocytes ,Time Factors ,Mice, Transgenic ,Lymphocyte Activation ,Article ,Mitochondria ,Mice, Inbred C57BL ,Glutamate Plasma Membrane Transport Proteins ,Mice ,Animals ,Female ,Energy Metabolism ,Reactive Oxygen Species ,Glycolysis ,Cells, Cultured ,Signal Transduction - Abstract
Activation of CD4(+) T cells to proliferate, drives cells towards aerobic glycolysis for energy production while using mitochondria primarily for macromolecular synthesis. In addition, the mitochondria of activated T cells increase production of reactive oxygen species (ROS) providing an important second messenger for intracellular signaling pathways. To better understand the critical changes in mitochondria that accompany prolonged T cell activation, we carried out an extensive analysis of mitochondrial remodeling using a combination of conventional strategies and a novel high-resolution imaging method. We show that for four days following activation, mouse CD4(+) T cells sustained their commitment to glycolysis facilitated by increased glucose uptake through increased expression of GLUT transporters. Despite their limited contribution to energy production, mitochondria were active and showed increased ROS production. Moreover, prolonged activation of CD4(+) T cells led to increases in mitochondrial content and volume, in the number of mitochondria per cell and in mitochondrial biogenesis. Thus, during prolonged activation, CD4(+) T cells continue to obtain energy predominantly from glycolysis but also undergo extensive mitochondrial remodeling resulting in increased mitochondrial activity.
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- 2018
16. T cell-dependent antigen adjuvanted with DOTAP-CpG-B but not DOTAP-CpG-A induces robust germinal center responses and high affinity antibodies in mice
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Chen-Feng Qi, Pietro Miozzo, Susan K. Pierce, Munir Akkaya, Javier Manzella-Lapeira, Billur Akkaya, Silvia Bolland, Patrick W. Sheehan, and Mirna Pena
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0301 basic medicine ,T cell ,medicine.medical_treatment ,T-Lymphocytes ,Immunology ,Antibody Affinity ,Biology ,Article ,Affinity maturation ,Fatty Acids, Monounsaturated ,03 medical and health sciences ,Mice ,0302 clinical medicine ,Antigen ,Adjuvants, Immunologic ,medicine ,Immunology and Allergy ,Animals ,Vaccines ,TLR9 ,Germinal center ,Germinal Center ,Mice, Inbred C57BL ,Quaternary Ammonium Compounds ,030104 developmental biology ,medicine.anatomical_structure ,Immunoglobulin class switching ,Oligodeoxyribonucleotides ,biology.protein ,Antibody ,Adjuvant ,030215 immunology - Abstract
The development of vaccines for infectious diseases for which we currently have none, including HIV, will likely require the use of adjuvants that strongly promote germinal center responses and somatic hypermutation to produce broadly neutralizing antibodies. Here we compared the outcome of immunization with the T-cell dependent antigen, NP-conjugated to chicken gamma globulin (NP-CGG) adjuvanted with the toll-like receptor 9 (TLR9) ligands, CpG-A or CpG-B, alone or conjugated with the cationic lipid carrier, DOTAP. We provide evidence that only NP-CGG adjuvanted with DOTAP-CpG-B was an effective vaccine in mice resulting in robust germinal center responses, isotype switching and high affinity NP-specific antibodies. The effectiveness of DOTAP-CpG-B as an adjuvant was dependent on the expression of the TLR9 signaling adaptor MyD88 in immunized mice. These results indicate DOTAP-CpG-B but not DOTAP-CpG-A is an effective adjuvant for T cell-dependent protein antigen-based vaccines.
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- 2017
17. Malaria Immunity in Man and Mosquito: Insights into Unsolved Mysteries of a Deadly Infectious Disease
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Michael Waisberg, Carolina Barillas-Mury, Lindsey S. Garver, Silvia Portugal, Geoffrey T. Hart, Susan K. Pierce, Peter D. Crompton, Jacqueline Moebius, and Louis H. Miller
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Plasmodium ,medicine.medical_specialty ,Plasmodium falciparum ,Immunology ,Immune resistance ,Disease ,Biology ,Article ,Immunity ,parasitic diseases ,medicine ,Animals ,Humans ,Immunology and Allergy ,Intensive care medicine ,Life Cycle Stages ,Malaria vaccine ,medicine.disease ,biology.organism_classification ,Malaria ,Culicidae ,Infectious disease (medical specialty) ,Host-Pathogen Interactions - Abstract
Malaria is a mosquito-borne disease caused by parasites of the obligate intracellular Apicomplexa phylum the most deadly of which, Plasmodium falciparum, prevails in Africa. Malaria imposes a huge health burden on the world's most vulnerable populations, claiming the lives of nearly one million children and pregnant women each year. Although there is keen interest in eradicating malaria, we do not yet have the necessary tools to meet this challenge, including an effective malaria vaccine and adequate vector control strategies. Here we review what is known about the mechanisms at play in immune resistance to malaria in both the human and mosquito hosts at each step in the parasite's complex life cycle with a view toward developing the tools that will contribute to the prevention of disease and death and, ultimately, to the goal of malaria eradication. In so doing, we hope to inspire immunologists to participate in defeating this devastating disease.
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- 2014
18. CD8(+) T Cells Induce Fatal Brainstem Pathology during Cerebral Malaria via Luminal Antigen-Specific Engagement of Brain Vasculature
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Geoffrey T. Hart, Debasis Nayak, Matthew V. Russo, Chris J. Janse, Shahid M. Khan, Phillip A. Swanson, Takele Yazew, Mirna Pena, Dorian B. McGavern, and Susan K. Pierce
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Central Nervous System ,0301 basic medicine ,Pathology ,Plasmodium berghei ,CD8-Positive T-Lymphocytes ,Nervous System ,Pathogenesis ,Mice ,White Blood Cells ,0302 clinical medicine ,Animal Cells ,Medicine and Health Sciences ,Cytotoxic T cell ,Biology (General) ,Neuronal Death ,Cell Death ,biology ,T Cells ,Brain ,Flow Cytometry ,Immunohistochemistry ,medicine.anatomical_structure ,Blood-Brain Barrier ,Cell Processes ,Cerebral Malaria ,Cellular Types ,Anatomy ,Brainstem ,Research Article ,Programmed cell death ,medicine.medical_specialty ,QH301-705.5 ,Immune Cells ,T cell ,Immunology ,Malaria, Cerebral ,Mice, Transgenic ,Cytotoxic T cells ,Microbiology ,03 medical and health sciences ,Antigen ,Virology ,MHC class I ,Parasitic Diseases ,Genetics ,medicine ,Animals ,Molecular Biology ,Blood Cells ,Biology and Life Sciences ,Cell Biology ,RC581-607 ,Tropical Diseases ,Malaria ,Disease Models, Animal ,030104 developmental biology ,Cardiovascular Anatomy ,biology.protein ,Blood Vessels ,Parasitology ,Immunologic diseases. Allergy ,CD8 ,Brain Stem ,030215 immunology - Abstract
Cerebral malaria (CM) is a severe complication of Plasmodium falciparum infection that results in thousands of deaths each year, mostly in African children. The in vivo mechanisms underlying this fatal condition are not entirely understood. Using the animal model of experimental cerebral malaria (ECM), we sought mechanistic insights into the pathogenesis of CM. Fatal disease was associated with alterations in tight junction proteins, vascular breakdown in the meninges / parenchyma, edema, and ultimately neuronal cell death in the brainstem, which is consistent with cerebral herniation as a cause of death. At the peak of ECM, we revealed using intravital two-photon microscopy that myelomonocytic cells and parasite-specific CD8+ T cells associated primarily with the luminal surface of CNS blood vessels. Myelomonocytic cells participated in the removal of parasitized red blood cells (pRBCs) from cerebral blood vessels, but were not required for the disease. Interestingly, the majority of disease-inducing parasite-specific CD8+ T cells interacted with the lumen of brain vascular endothelial cells (ECs), where they were observed surveying, dividing, and arresting in a cognate peptide-MHC I dependent manner. These activities were critically dependent on IFN-γ, which was responsible for activating cerebrovascular ECs to upregulate adhesion and antigen-presenting molecules. Importantly, parasite-specific CD8+ T cell interactions with cerebral vessels were impaired in chimeric mice rendered unable to present EC antigens on MHC I, and these mice were in turn resistant to fatal brainstem pathology. Moreover, anti-adhesion molecule (LFA-1 / VLA-4) therapy prevented fatal disease by rapidly displacing luminal CD8+ T cells from cerebrovascular ECs without affecting extravascular T cells. These in vivo data demonstrate that parasite-specific CD8+ T cell-induced fatal vascular breakdown and subsequent neuronal death during ECM is associated with luminal, antigen-dependent interactions with cerebrovasculature., Author Summary Cerebral malaria (CM) is a severe and potentially fatal complication of malaria in humans that results in swelling and bleeding within the brain. The mechanisms that cause this fatal disease in humans are not completely understood. We studied an animal model known as experimental cerebral malaria to learn more about the factors that drive this disease process. Using a technique referred to as intravital microscopy, we captured movies of immune cells operating in the living brain as the disease developed. At the peak of disease, we observed evidence of immune cells interacting with and aggregating along blood vessels throughout the brain. These interactions were directly associated vascular leakage. This caused the brain to swell, which gave rise to an unsustainable pressure that ultimately killed neurons responsible for heart and lung function. The fatal swelling was induced by immune cells (referred to as T cells) interacting with bits of parasite presented by blood vessels in the brain. Removal of this parasite presentation protected the mice from fatal disease. We also evaluated a straightforward therapy that involved intravenous administration of antibodies that interfered with T cell sticking to blood vessels. Our movies revealed that this therapeutic approach rapidly displaced T cells from the blood vessels in the brain and prevented fatal disease.
- Published
- 2016
19. An Optimized Protocol to Analyze Glycolysis and Mitochondrial Respiration in Lymphocytes
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Javier Traba, Billur Akkaya, Munir Akkaya, Pietro Miozzo, and Susan K. Pierce
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lymphocytes ,0301 basic medicine ,Cell type ,General Chemical Engineering ,medicine.medical_treatment ,Lymphocyte ,Immunology ,T cells ,Mitochondrion ,Biology ,General Biochemistry, Genetics and Molecular Biology ,Mice ,03 medical and health sciences ,Immune system ,Issue 117 ,Extracellular ,medicine ,Animals ,magnetic separation ,mouse ,B cells ,General Immunology and Microbiology ,General Neuroscience ,glycolysis ,extracellular flux ,Mitochondria ,Cell biology ,030104 developmental biology ,Cytokine ,medicine.anatomical_structure ,Biochemistry ,Biological Assay ,Signal transduction ,metabolism ,Flux (metabolism) ,respiration ,Signal Transduction - Abstract
Lymphocytes respond to a variety of stimuli by activating intracellular signaling pathways, which in turn leads to rapid cellular proliferation, migration and differentiation, and cytokine production. All of these events are tightly linked to the energy status of the cell, and therefore studying the energy-producing pathways may give clues about the overall functionality of these cells. The extracellular flux analyzer is a commonly used device for evaluating the performance of glycolysis and mitochondrial respiration in many cell types. This system has been used to study immune cells in a few published reports, yet a comprehensive protocol optimized particularly for lymphocytes is lacking. Lymphocytes are fragile cells that survive poorly in ex vivo conditions. Oftentimes lymphocyte subsets are rare, and working with low cell numbers is inevitable. Thus, an experimental strategy that addresses these difficulties is required. Here, we provide a protocol that allows for rapid isolation of viable lymphocytes from lymphoid tissues, and for the analysis of their metabolic states in the extracellular flux analyzer. Furthermore, we provide results of experiments in which the metabolic activities of several lymphocyte subtypes at different cell densities were compared. These observations suggest that our protocol can be used to achieve consistent, well-standardized results even at low cell concentrations, and thus it may have broad applications in future studies focusing on the characterization of metabolic events in immune cells.
- Published
- 2016
20. The persistence of low-grade inflammatory monocytes contributes to aggravated atherosclerosis
- Author
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Susan K. Pierce, Yao Zhang, Wenhua Ling, Chun Chen, Keqiang Chen, Yuan Hu, Liwu Li, Liang Peng, Urmila Maitra, Na Diao, Ruoxi Yuan, Shuo Geng, Huabao Xiong, and Chen-Feng Qi
- Subjects
0301 basic medicine ,Lipopolysaccharides ,Science ,Regulator ,General Physics and Astronomy ,Inflammation ,General Biochemistry, Genetics and Molecular Biology ,Article ,Monocytes ,Pathogenesis ,03 medical and health sciences ,0302 clinical medicine ,Medicine ,Animals ,Homeostasis ,Base sequence ,Scavenger receptor ,Subclinical infection ,Smad4 Protein ,Multidisciplinary ,Base Sequence ,business.industry ,Monocyte homeostasis ,Cell Polarity ,General Chemistry ,Scavenger Receptors, Class B ,Atherosclerosis ,Endotoxemia ,Mice, Inbred C57BL ,MicroRNAs ,030104 developmental biology ,Interleukin-1 Receptor-Associated Kinases ,030220 oncology & carcinogenesis ,Immunology ,Disease Progression ,medicine.symptom ,business - Abstract
Sustained low-grade inflammation mediated by non-resolving inflammatory monocytes has long been suspected in the pathogenesis of atherosclerosis; however, the molecular mechanisms responsible for the sustainment of non-resolving inflammatory monocytes during atherosclerosis are poorly understood. Here we observe that subclinical endotoxemia, often seen in humans with chronic inflammation, aggravates murine atherosclerosis through programming monocytes into a non-resolving inflammatory state with elevated Ly6C, CCR5, MCP-1 and reduced SR-B1. The sustainment of inflammatory monocytes is due to the disruption of homeostatic tolerance through the elevation of miR-24 and reduction of the key negative-feedback regulator IRAK-M. miR-24 reduces the levels of Smad4 required for the expression of IRAK-M and also downregulates key lipid-processing molecule SR-B1. IRAK-M deficiency in turn leads to elevated miR-24 levels, sustains disruption of monocyte homeostasis and aggravates atherosclerosis. Our data define an integrated feedback circuit in monocytes and its disruption may lead to non-resolving low-grade inflammation conducive to atherosclerosis., Chronic low-grade inflammation has been suspected to promote atherosclerosis. Here, Geng et al. show that sustained low-grade inflammation promotes atherosclerosis in mice via monocyte programing that involves a coupled disruption of IRAK-M regulation and induction of miR-24.
- Published
- 2016
21. Encoding Immunological Memory in the Initiation of B-Cell Receptor Signaling
- Author
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Wanli Liu and Susan K. Pierce
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Cytoplasm ,Amino Acid Motifs ,B-cell receptor ,Naive B cell ,Biochemistry ,Immunoglobulin D ,Article ,Immunoglobulin G ,Mice ,Genetics ,medicine ,Animals ,Humans ,Antigens ,Molecular Biology ,B cell ,B-Lymphocytes ,biology ,Cell Membrane ,Receptors, IgG ,Germinal center ,Cell biology ,B-1 cell ,medicine.anatomical_structure ,Immunoglobulin M ,Immunology ,biology.protein ,Signal transduction ,Immunologic Memory ,Signal Transduction - Abstract
In one of the earliest events in the initiation of antigen-driven antibody responses, naïve, IgM-, and IgD-expressing B cells enter germinal centers where they irreversibly isotype switch to the expression of predominately IgG B-cell receptors (BCRs). The IgG-expressing B cells then undergo rounds of antigen-driven selection, ultimately exiting germinal centers as IgG-expressing memory B cells or plasma blast. This early switch from IgM to IgG begs the question: Of what advantage to the memory response is the B cell's expression of an IgG BCR? Despite convincing evidence that the expression of IgG BCRs is essential for antibody memory responses in vivo, the molecular basis of this requirement is only incompletely understood. Here we describe intrinsic features of IgG BCRs that endow memory B cells with the ability to rapidly and efficiently initiate signaling. Remarkably, efficient signaling is mediated through the cytoplasmic tail of the membrane IgG that binds to synapse associated protein 97, a member of a large family of proteins that are best studied for their role in regulating receptor signaling in neuronal synapses. These findings underscore an interesting parallel in the mechanisms at play in encoding immunological memory and memory in the nervous system.
- Published
- 2013
22. Formation of BCR oligomers provides a mechanism for B cell affinity discrimination
- Author
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Subhadip Raychaudhuri, C Das Somkanya, Susan K. Pierce, Wanli Liu, Philippos K. Tsourkas, and Paul Yu-Yang
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Statistics and Probability ,Cell signaling ,Time Factors ,B-cell receptor ,Antibody Affinity ,FOS: Physical sciences ,Receptors, Antigen, B-Cell ,Biology ,Article ,General Biochemistry, Genetics and Molecular Biology ,Antigen ,LYN ,Cell Behavior (q-bio.CB) ,medicine ,Animals ,Syk Kinase ,Computer Simulation ,Physics - Biological Physics ,Antigens ,Phosphorylation ,Protein Structure, Quaternary ,B cell ,B-Lymphocytes ,General Immunology and Microbiology ,Applied Mathematics ,Intracellular Signaling Peptides and Proteins ,Models, Immunological ,breakpoint cluster region ,General Medicine ,Protein-Tyrosine Kinases ,Kinetics ,medicine.anatomical_structure ,Biochemistry ,Biological Physics (physics.bio-ph) ,FOS: Biological sciences ,Modeling and Simulation ,Biophysics ,Quantitative Biology - Cell Behavior ,Protein Multimerization ,Signal transduction ,General Agricultural and Biological Sciences ,Signal Transduction - Abstract
B cells encounter antigen over a wide affinity range. The strength of B cell signaling in response to antigen increases with affinity, a process known as "affinity discrimination". In this work, we use a computational simulation of B cell surface dynamics and signaling to show that affinity discrimination can arise from the formation of BCR oligomers. It is known that BCRs form oligomers upon encountering antigen, and that the size and rate of formation of these oligomers increase with affinity. In our simulation, we have introduced a requirement that only BCR-antigen complexes that are part of an oligomer can engage cytoplasmic signaling molecules such as Src-family kinases. Our simulation shows that as affinity increases, not only does the number of collected antigen increases, but so does signaling activity. Our results are also consistent with the existence of an experimentally-observed threshold affinity of activation (no signaling activity below this affinity value) and affinity discrimination ceiling (no affinity discrimination above this affinity value). Comparison with experiments shows that the time scale of dimer formation predicted by our model (less than 10 s) is well within the time scale of experimentally observed association of BCR with Src-family kinases (10-20 s)., 29 pages, 9 figures
- Published
- 2012
23. Plasmodium falciparum merozoite surface protein 1 blocks the proinflammatory protein S100P
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Thomas L. Leto, Michael Waisberg, Balázs Rada, Jinghua Lu, Jan Lukszo, Susan K. Pierce, Louis H. Miller, Stephanie B. Yager, Ivo M.B. Francischetti, Prakash Srinivasan, Kent D. Barbian, Nidhi Gera, Gustavo C. Cerqueira, Stephen F. Porcella, Kazutoyo Miura, Najib M. El-Sayed, and David L. Narum
- Subjects
Two-hybrid screening ,Molecular Sequence Data ,Plasmodium falciparum ,Enzyme-Linked Immunosorbent Assay ,Biology ,Proinflammatory cytokine ,Microbiology ,Immune system ,Calcium-binding protein ,parasitic diseases ,Animals ,Humans ,Parasite hosting ,Amino Acid Sequence ,Peptide sequence ,Merozoite Surface Protein 1 ,Microscopy, Confocal ,Multidisciplinary ,Sequence Homology, Amino Acid ,Calcium-Binding Proteins ,Chemotaxis ,Surface Plasmon Resonance ,Biological Sciences ,biology.organism_classification ,Molecular biology ,Neoplasm Proteins ,Chromatography, Gel ,Electrophoresis, Polyacrylamide Gel - Abstract
The malaria parasite, Plasmodium falciparum , and the human immune system have coevolved to ensure that the parasite is not eliminated and reinfection is not resisted. This relationship is likely mediated through a myriad of host–parasite interactions, although surprisingly few such interactions have been identified. Here we show that the 33-kDa fragment of P. falciparum merozoite surface protein 1 (MSP1 33 ), an abundant protein that is shed during red blood cell invasion, binds to the proinflammatory protein, S100P. MSP1 33 blocks S100P-induced NFκB activation in monocytes and chemotaxis in neutrophils. Remarkably, S100P binds to both dimorphic alleles of MSP1, estimated to have diverged >27 Mya, suggesting an ancient, conserved relationship between these parasite and host proteins that may serve to attenuate potentially damaging inflammatory responses.
- Published
- 2012
24. Development and clinical evaluation of multiple investigational monovalent DENV vaccines to identify components for inclusion in a live attenuated tetravalent DENV vaccine
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Stephen S. Whitehead, Anna P. Durbin, Alexander C. Schmidt, Kristen K. Pierce, and Beth D. Kirkpatrick
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Serotype ,Dengue Vaccines ,Mice, SCID ,Vaccines, Attenuated ,Article ,Dengue fever ,Mice ,Aedes ,Animals ,Humans ,Medicine ,Dengue vaccine ,Clinical Trials as Topic ,General Veterinary ,General Immunology and Microbiology ,biology ,business.industry ,Public Health, Environmental and Occupational Health ,biology.organism_classification ,medicine.disease ,Macaca mulatta ,Virology ,Clinical trial ,Disease Models, Animal ,Infectious Diseases ,Immunology ,Molecular Medicine ,business ,Clinical evaluation - Abstract
The Laboratory of Infectious Diseases at the National Institute of Allergy and Infectious Diseases, National Institutes of Health has been engaged in an effort to develop a safe, efficacious, and affordable live attenuated tetravalent dengue vaccine (LATV) for more than ten years. Numerous recombinant monovalent DENV vaccine candidates have been evaluated in the SCID-HuH-7 mouse and in rhesus macaques to identify those candidates with a suitable attenuation phenotype. In addition, the ability of these candidates to infect and disseminate in Aedes mosquitoes had also been determined. Those candidates that were suitably attenuated in SCID-HuH-7 mice, rhesus macaques, and mosquitoes were selected for further evaluation in humans. This review will describe the generation of multiple candidate vaccines directed against each DENV serotype, the preclinical and clinical evaluation of these candidates, and the process of selecting suitable candidates for inclusion in a LATV dengue vaccine.
- Published
- 2011
25. Binding of Plasmodium merozoite proteins RON2 and AMA1 triggers commitment to invasion
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J. David Haynes, David L. Narum, Xavier Ambroggio, Prakash Srinivasan, Wandy L. Beatty, Louis H. Miller, John C. Boothroyd, Susan K. Pierce, Jessica S. Tyler, Ababacar Diouf, Raul Herrera, and J. Kathleen Moch
- Subjects
Cytochalasin D ,Erythrocytes ,Molecular Sequence Data ,Plasmodium falciparum ,Protozoan Proteins ,Antibodies, Protozoan ,Plasma protein binding ,Biology ,Models, Biological ,complex mixtures ,Conserved sequence ,Structure-Activity Relationship ,Fructose-Bisphosphate Aldolase ,parasitic diseases ,Animals ,Amino Acid Sequence ,Cysteine ,Apical membrane antigen 1 ,Binding site ,Peptide sequence ,Conserved Sequence ,Binding Sites ,Multidisciplinary ,Merozoites ,fungi ,Biological Sciences ,biology.organism_classification ,Transport protein ,Cell biology ,Protein Transport ,Rhoptry neck ,Hydrophobic and Hydrophilic Interactions ,Protein Binding - Abstract
The commitment of Plasmodium merozoites to invade red blood cells (RBCs) is marked by the formation of a junction between the merozoite and the RBC and the coordinated induction of the parasitophorous vacuole. Despite its importance, the molecular events underlying the parasite’s commitment to invasion are not well understood. Here we show that the interaction of two parasite proteins, RON2 and AMA1, known to be critical for invasion, is essential to trigger junction formation. Using antibodies (Abs) that bind near the hydrophobic pocket of AMA1 and AMA1 mutated in the pocket, we identified RON2’s binding site on AMA1. Abs specific for the AMA1 pocket blocked junction formation and the induction of the parasitophorous vacuole. We also identified the critical residues in the RON2 peptide (previously shown to bind AMA1) that are required for binding to the AMA1 pocket, namely, two conserved, disulfide-linked cysteines. The RON2 peptide blocked junction formation but, unlike the AMA1-specific Ab, did not block formation of the parasitophorous vacuole, indicating that formation of the junction and parasitophorous vacuole are molecularly distinct steps in the invasion process. Collectively, these results identify the binding of RON2 to the hydrophobic pocket of AMA1 as the step that commits Plasmodium merozoites to RBC invasion and point to RON2 as a potential vaccine candidate.
- Published
- 2011
26. Advances and challenges in malaria vaccine development
- Author
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Louis H. Miller, Peter D. Crompton, and Susan K. Pierce
- Subjects
Adult ,Male ,medicine.medical_specialty ,Plasmodium falciparum ,Antigens, Protozoan ,Biology ,Pregnancy ,Environmental health ,Malaria Vaccines ,parasitic diseases ,medicine ,Animals ,Humans ,Malaria, Falciparum ,Child ,Disease burden ,Clinical Trials as Topic ,Malaria vaccine ,Public health ,General Medicine ,Acquired immune system ,medicine.disease ,biology.organism_classification ,Vaccination ,Immunology ,Science in Medicine ,Female ,Malaria falciparum ,Malaria - Abstract
Malaria caused by Plasmodium falciparum remains a major public health threat, especially among children and pregnant women in Africa. An effective malaria vaccine would be a valuable tool to reduce the disease burden and could contribute to elimination of malaria in some regions of the world. Current malaria vaccine candidates are directed against human and mosquito stages of the parasite life cycle, but thus far, relatively few proteins have been studied for potential vaccine development. The most advanced vaccine candidate, RTS,S, conferred partial protection against malaria in phase II clinical trials and is currently being evaluated in a phase III trial in Africa. New vaccine targets need to be identified to improve the chances of developing a highly effective malaria vaccine. A better understanding of the mechanisms of naturally acquired immunity to malaria may lead to insights for vaccine development.
- Published
- 2010
27. Structural and Functional Studies of Igαβ and Its Assembly with the B Cell Antigen Receptor
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Zhongcheng Zou, Pavel Tolar, Susan K. Pierce, Sergei Radaev, Anh Nguyen, Peter D. Sun, Nicole Stutzman, Peter D. Krueger, and Khanh Q. Nguyen
- Subjects
Models, Molecular ,Protein Folding ,PROTEINS ,Protein Conformation ,DNA Mutational Analysis ,Molecular Sequence Data ,Receptors, Antigen, B-Cell ,Sequence alignment ,Plasma protein binding ,Biology ,Article ,Mice ,Protein structure ,Species Specificity ,Structural Biology ,medicine ,Animals ,Humans ,Amino Acid Sequence ,MOLIMMUNO ,Molecular Biology ,Peptide sequence ,B cell ,DNA Primers ,Crystallography ,Base Sequence ,breakpoint cluster region ,Surface Plasmon Resonance ,Cell biology ,medicine.anatomical_structure ,Biochemistry ,biology.protein ,Protein folding ,Antibody ,Dimerization ,Sequence Alignment ,CD79 Antigens - Abstract
The B cell antigen receptor (BCR) plays an essential role in all phases of B cell development. Here we show that the extracellular domains of murine and human Igbeta form an I-set immunoglobulin-like structure with an interchain disulfide between cysteines on their G strands. Structural and sequence analysis suggests that Igalpha displays a similar fold as Igbeta. An Igalphabeta heterodimer model was generated based on the unique disulfide-bonded Igbeta dimer. Solution binding studies showed that the extracellular domains of Igalphabeta preferentially recognize the constant region of BCR with mu chain specificity, suggesting a role for Igalphabeta to enhance BCRmu chain signaling. Cluster mutations on Igalpha, Igbeta, and a membrane-bound form of immunoglobulin (mIgM) based on the structural model identified distinct areas of potential contacts involving charged residues on both subunits of the coreceptor and the Cmu4 domain of mIgM. These studies provide the first structural model for understanding BCR function.
- Published
- 2010
28. A prospective analysis of the Ab response to Plasmodium falciparum before and after a malaria season by protein microarray
- Author
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Philip L. Felgner, Denise L. Doolan, Peter D. Crompton, Susan K. Pierce, Algis Jasinskas, David L. Narum, Greta E Weiss, Louis H. Miller, Xiaowu Liang, Didier Doumtabe, Michael Waisberg, Ogobara K. Doumbo, Douglas M. Molina, Matthew A. Kayala, Pierre Baldi, Safiatou Doumbo, Chad Burk, Kassoum Kayentao, Boubacar Traore, Xiaolin Tan, Younoussou Kone, and Aissata Ongoiba
- Subjects
Adult ,Proteomics ,Adolescent ,Microarray ,Plasmodium falciparum ,Protein Array Analysis ,Antigens, Protozoan ,Mali ,Immunomics ,Cohort Studies ,Antigen ,Immunity ,Malaria Vaccines ,parasitic diseases ,medicine ,Animals ,Humans ,Malaria, Falciparum ,Child ,Multidisciplinary ,biology ,Malaria vaccine ,Biological Sciences ,biology.organism_classification ,medicine.disease ,Virology ,Child, Preschool ,Immune System ,Immunology ,biology.protein ,Antibody ,Malaria - Abstract
Abs are central to malaria immunity, which is only acquired after years of exposure to Plasmodium falciparum ( Pf ). Despite the enormous worldwide burden of malaria, the targets of protective Abs and the basis of their inefficient acquisition are unknown. Addressing these knowledge gaps could accelerate malaria vaccine development. To this end, we developed a protein microarray containing ∼23% of the Pf 5,400-protein proteome and used this array to probe plasma from 220 individuals between the ages of 2–10 years and 18–25 years in Mali before and after the 6-month malaria season. Episodes of malaria were detected by passive surveillance over the 8-month study period. Ab reactivity to Pf proteins rose dramatically in children during the malaria season; however, most of this response appeared to be short-lived based on cross-sectional analysis before the malaria season, which revealed only modest incremental increases in Ab reactivity with age. Ab reactivities to 49 Pf proteins measured before the malaria season were significantly higher in 8–10-year-old children who were infected with Pf during the malaria season but did not experience malaria ( n = 12) vs. those who experienced malaria ( n = 29). This analysis also provided insight into patterns of Ab reactivity against Pf proteins based on the life cycle stage at which proteins are expressed, subcellular location, and other proteomic features. This approach, if validated in larger studies and in other epidemiological settings, could prove to be a useful strategy for better understanding fundamental properties of the human immune response to Pf and for identifying previously undescribed vaccine targets.
- Published
- 2010
29. Autophagy in immune cell regulation and dysregulation
- Author
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Susan K. Pierce and Akanksha Chaturvedi
- Subjects
Pulmonary and Respiratory Medicine ,Premature aging ,Programmed cell death ,Cell type ,T-Lymphocytes ,Immunology ,Cell ,Thymus Gland ,Biology ,Immune system ,Autophagy ,medicine ,Animals ,Humans ,Immunology and Allergy ,Tissue homeostasis ,Antigen Presentation ,B-Lymphocytes ,Histocompatibility Antigens Class I ,Neurodegeneration ,Histocompatibility Antigens Class II ,medicine.disease ,Cell biology ,medicine.anatomical_structure ,Receptors, Pattern Recognition ,Signal Transduction - Abstract
Autophagy is an ancient pathway required for cell and tissue homeostasis and differentiation. Initially thought to be a process leading to cell death, autophagy is currently viewed as a beneficial catabolic process that promotes cell survival under starvation conditions by sequestering components of the cytoplasm, including misfolded proteins, protein aggregates, and damaged organelles, and targeting them for lysosome-mediated degradation. In this way, autophagy plays a role in maintaining a balance between degradation and recycling of cellular material. The importance of autophagy is underscored by the fact that malfunctioning of this pathway results in neurodegeneration, cancer, susceptibility to microbial infection, and premature aging. Autophagy occurs in almost all cell types, including immune cells. Recent advances in the field suggest that autophagy plays a central role in regulating the immune system at multiple levels. In this review, we focus on recent developments in the area of autophagy-mediated modulation of immune responses.
- Published
- 2009
30. Atypical Memory B Cells Are Greatly Expanded in Individuals Living in a Malaria-Endemic Area
- Author
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Shanping Li, Peter D. Crompton, Susan Moir, Aissata Ongoiba, Susan K. Pierce, Laura A. Walsh, Boubacar Traore, Kassoum Kayentao, Ogobara K. Doumbo, and Greta E Weiss
- Subjects
Adult ,Adolescent ,Endemic Diseases ,Plasmodium falciparum ,Immunology ,Population ,Prevalence ,Receptors, Fc ,Article ,Immunophenotyping ,Young Adult ,parasitic diseases ,polycyclic compounds ,medicine ,Animals ,Humans ,Immunology and Allergy ,Young adult ,Child ,education ,B cell ,Cell Proliferation ,B-Lymphocytes ,education.field_of_study ,biology ,biology.organism_classification ,medicine.disease ,Virology ,Malaria ,medicine.anatomical_structure ,Case-Control Studies ,Child, Preschool ,Immunologic Memory ,Viral load - Abstract
Epidemiological observations in malaria endemic areas have long suggested a deficiency in the generation and maintenance of B cell memory to Plasmodium falciparum (Pf) in individuals chronically reinfected with the parasite. Recently, a functionally and phenotypically distinct population of FCRL4+ hyporesponsive memory B cells (MBCs) was reported to be expanded in HIV-infected individuals with high viral loads. In this study, we provide evidence that a phenotypically similar atypical MBC population is significantly expanded in Pf-exposed Malian adults and children as young as 2 years of age as compared with healthy U.S. adult controls. The number of these atypical MBCs was higher in children with chronic asymptomatic Pf infections compared with uninfected children, suggesting that the chronic presence of the parasite may drive expansion of these distinct MBCs. This is the first description of an atypical MBC phenotype associated with malaria. Understanding the origin and function of these MBCs could be important in informing the design of malaria vaccines.
- Published
- 2009
31. How Location Governs Toll-Like Receptor Signaling
- Author
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Akanksha Chaturvedi and Susan K. Pierce
- Subjects
Toll-like receptor ,Innate immune system ,Toll-Like Receptors ,Cell Biology ,Biology ,Biochemistry ,Article ,Cell biology ,Protein Transport ,Immune system ,Downregulation and upregulation ,Structural Biology ,Genetics ,Animals ,Humans ,Secretion ,Signal transduction ,Receptor ,Molecular Biology ,Intracellular ,Signal Transduction - Abstract
Toll-like receptors (TLRs) are a family of innate immune system receptors responsible for recognizing conserved pathogen-associated molecular patterns (PAMPs). PAMP binding to TLRs initiates intracellular signaling pathways that lead to the upregulation of a variety of costimulatory molecules and the synthesis and secretion of various cytokines and interferons by cells of the innate immune system. TLR-induced innate immune responses are a prerequisite for the generation of most adaptive immune responses, and in the case of B cells, TLRs directly regulate signaling from the antigen-specific B-cell receptor. The outcome of TLR signaling is determined, in part, by the cells in which they are expressed and by the selective use of signaling adaptors. Recent studies suggest that, in addition, both the ligand recognition by TLRs and the functional outcome of ligand binding are governed by the subcellular location of the TLRs and their signaling adaptors. In this review we describe what is known about the intracellular trafficking and compartmentalization of TLRs in innate system's dendritic cells and macrophages and in adaptive system's B cells, highlighting how location regulates TLR function.
- Published
- 2009
32. World Malaria Day 2009: What Malaria Knows about the Immune System That Immunologists Still Do Not
- Author
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Susan K. Pierce and Louis H. Miller
- Subjects
Tuberculosis ,Anopheles gambiae ,Plasmodium falciparum ,Immunology ,Drug Resistance ,Drug resistance ,Biology ,Article ,Immune system ,Acquired immunodeficiency syndrome (AIDS) ,Immunity ,Anopheles ,Malaria Vaccines ,parasitic diseases ,medicine ,Animals ,Humans ,Immunology and Allergy ,Child ,medicine.disease ,biology.organism_classification ,Insect Vectors ,Malaria ,Immune System ,Africa ,Female - Abstract
Malaria kills >1 million children each year, and there is little doubt that an effective vaccine would play a central role in preventing these deaths. However, the strategies that proved so successful in developing the vaccines we have today may simply not be adequate to confront complex, persistent infectious diseases, including malaria, AIDS, and tuberculosis. We believe that the development of a highly effective vaccine will require a better understanding of several features of the immune response to malaria. At the top of the list is the complex and ancient relationship between the parasite that causes malaria and the immune system that enables the parasite to persist in an otherwise functional immune system. A close second is the antigenic targets in malaria and how to overcome the enormous polymorphism of these targets. Meeting these challenges represents a call to arms of basic immunologists to advance our knowledge of malaria immunity.
- Published
- 2009
33. Change we can believe in—of the conformational type
- Author
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Susan K. Pierce and Pavel Tolar
- Subjects
T-cell receptor ,B-cell receptor ,Receptors, Antigen, T-Cell ,breakpoint cluster region ,Receptors, Antigen, B-Cell ,Review Article ,Biology ,Acquired immune system ,Models, Biological ,Biochemistry ,Immunological synapse ,Cell biology ,Receptors, Antigen ,Antigen ,Genetics ,Animals ,Humans ,Signal transduction ,Receptor ,Molecular Biology ,Signal Transduction - Abstract
The Cantoblanco Workshop on the Initiation of Antigen Receptor Signaling took place between 20 and 22 October 2008, in Cantoblanco, Madrid, Spain, and was organized by B. Alarcon, M. Davis & A. Weiss. ![][1] See Glossary for abbreviations used in this article In the back of our minds, we all know how antigen receptors trigger the activation of T‐ and B‐lymphocytes; it seems relatively well worked out. The binding of an antigen to the T‐cell receptor (TCR) and the B‐cell receptor (BCR) results in the phosphorylation of the cytoplasmic domains of these receptors, and off the cells go. Yet how exactly does that happen? For a group of researchers gathered in Madrid, Spain, in the autumn of 2008, that was the question. How does antigen binding to the ectodomains of the TCR and the BCR change the receptors so as to initiate intracellular signalling? Since the discovery of the TCR and the BCR, immunologists have learned a tremendous amount about the signalling cascades that are triggered by antigen binding and ultimately lead to T‐cell and B‐cell activation. However, the mechanisms that translate antigen binding into intracellular signalling remain among the real mysteries of adaptive immunity. How can that be if the mechanisms underlying the activation of a range of receptors—such as growth factor receptors—have been well worked out? In contrast to these conventional receptors, several unique characteristics of antigen receptors suggest that their inner workings are more complicated, including the enormous variability of their antigen‐binding domains and the need to learn to discriminate self from non‐self. How do the numerous unique interactions of antigens with the TCRs and BCRs expressed by each lymphocyte converge on a common change in the intracellular domains of the receptors that is sensitive to foreign antigens, but not self? To foster a discussion of antigen‐receptor activation, … [1]: /embed/graphic-1.gif
- Published
- 2009
34. The TLR9 Ligand CpG Promotes the Acquisition of Plasmodium falciparum-Specific Memory B Cells in Malaria-Naive Individuals
- Author
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F. Eun-Hyung Lee, Iñaki Sanz, Ruth D. Ellis, Anna P. Durbin, Peter D. Crompton, Marko Mircetic, Elissa Malkin, David L. Narum, Kazutoyo Miura, Amy W. Baughman, Laura B. Martin, Susan K. Pierce, Chiung Yu Huang, Gregory E. D. Mullen, John J. Treanor, David J. Topham, Louis H. Miller, and Greta E Weiss
- Subjects
Adult ,Plasmodium falciparum ,Immunology ,B-Lymphocyte Subsets ,Immunization, Secondary ,Aluminum Hydroxide ,Plasma cell ,Ligands ,Article ,Immune system ,Adjuvants, Immunologic ,Antigen ,Malaria Vaccines ,polycyclic compounds ,medicine ,Animals ,Humans ,Immunology and Allergy ,skin and connective tissue diseases ,neoplasms ,Cells, Cultured ,Innate immune system ,Clinical Trials, Phase I as Topic ,biology ,TLR9 ,bacterial infections and mycoses ,biology.organism_classification ,Malaria ,medicine.anatomical_structure ,Oligodeoxyribonucleotides ,CpG site ,Toll-Like Receptor 9 ,biology.protein ,Epitopes, B-Lymphocyte ,bacteria ,CpG Islands ,Antibody ,Immunologic Memory - Abstract
Despite the central role of memory B cells (MBC) in protective immune responses, little is understood about how they are acquired in naive individuals in response to Ag exposure, and how this process is influenced by concurrent activation of the innate immune system’s TLR. In this longitudinal study of malaria-naive individuals, we examined the MBC response to two candidate malaria vaccines administered with or without CpG, a TLR9 ligand. We show that the acquisition of MBC is a dynamic process in which the vaccine-specific MBC pool rapidly expands and then contracts, and that CpG enhances the kinetics, magnitude, and longevity of this response. We observed that the percentage of vaccine-specific MBC present at the time of reimmunization predicts vaccine-specific Ab levels 14 days later; and that at steady-state, there is a positive correlation between vaccine-specific MBC and Ab levels. An examination of the total circulating MBC and plasma cell pools also suggests that MBC differentiate into plasma cells through polyclonal activation, independent of Ag specificity. These results provide important insights into the human MBC response, which can inform the development of vaccines against malaria and other pathogens that disrupt immunological memory.
- Published
- 2009
35. The Constant Region of the Membrane Immunoglobulin Mediates B Cell-Receptor Clustering and Signaling in Response to Membrane Antigens
- Author
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Pavel Tolar, Joseph Hanna, Peter D. Krueger, and Susan K. Pierce
- Subjects
Conformational change ,B-cell receptor ,Immunology ,Receptors, Antigen, B-Cell ,Biology ,Lymphocyte Activation ,Article ,Cell membrane ,Mice ,Antigen ,hemic and lymphatic diseases ,medicine ,Animals ,Syk Kinase ,Immunology and Allergy ,Mice, Knockout ,B-Lymphocytes ,Mice, Inbred BALB C ,Cell Membrane ,Intracellular Signaling Peptides and Proteins ,breakpoint cluster region ,Nitrohydroxyiodophenylacetate ,Protein-Tyrosine Kinases ,Intercellular Adhesion Molecule-1 ,Cell biology ,MOLIMMUN ,medicine.anatomical_structure ,Infectious Diseases ,biology.protein ,Immunoglobulin Constant Region ,Signal transduction ,Antibody ,Immunoglobulin Constant Regions ,Signal Transduction - Abstract
B cells are activated in vivo after the B cell receptors (BCRs) bind to antigens captured on the surfaces of antigen-presenting cells. Antigen binding results in BCR microclustering and signaling; however, the molecular nature of the signaling-active BCR clusters is not well understood. Using single-molecule imaging techniques, we provide evidence that within microclusters, the binding of monovalent membrane antigens results in the assembly of immobile signaling-active BCR oligomers. The oligomerization depends on interactions between the membrane-proximal Cmicro4 domains of the membrane immunoglobulin that are both necessary and sufficient for assembly. Antigen-bound BCRs that lacked the Cmicro4 domain failed to cluster and signal, and conversely, Cmicro4 domains alone clustered spontaneously and activated B cells. These results support a unique mechanism for the initiation of BCR signaling in which antigen binding induces a conformational change in the Fc portion of the BCR, revealing an interface that promotes BCR clustering.
- Published
- 2009
- Full Text
- View/download PDF
36. The Agonists of TLR4 and 9 Are Sufficient to Activate Memory B Cells to Differentiate into Plasma Cells In Vitro but Not In Vivo
- Author
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Susan K. Pierce, Wenxia Song, and Katharina Richard
- Subjects
CpG Oligodeoxynucleotide ,Immunology ,Naive B cell ,B-cell receptor ,Lymphocyte Activation ,Article ,Mice ,medicine ,Animals ,Immunology and Allergy ,Memory B cell ,Cells, Cultured ,B cell ,B-Lymphocytes ,CD40 ,biology ,Cell Differentiation ,Cell biology ,Mice, Inbred C57BL ,Toll-Like Receptor 4 ,B-1 cell ,Phenotype ,medicine.anatomical_structure ,Toll-Like Receptor 7 ,Immunoglobulin class switching ,Immunoglobulin G ,Toll-Like Receptor 9 ,biology.protein ,Immunologic Memory - Abstract
Memory B cells can persist for a lifetime and be reactivated to yield high affinity, isotype switched plasma cells. The generation of memory B cells by Ag immunization requires adjuvants that generally contain TLR agonists. However, requirements for memory B cell activation and the role of TLRs in this activation are not well understood. In this study, we analyzed the response of memory B cells from immunized mice to TLR9 and 4 agonists CpG oligodeoxynucleotides (ODN) and LPS. Mouse memory B cells express both TLR9 and 4, and respond to both CpG ODN and LPS in vitro by differentiating into high affinity IgG secreting plasma cells. In contrast, neither CpG ODN nor LPS alone is sufficient to activate memory B cells in vivo. Ag is required for the clonal expansion of Ag-specific memory B cells, the differentiation of memory B cells to high affinity IgG secreting plasma cells, and the recall of high affinity Ab responses. The Ag-specific B cells that have not yet undergone isotype switching showed a relatively higher expression of TLR4 than memory B cells, which was reflected in a heightened response to LPS, but in both cases yielded mostly low affinity IgM secreting plasma cells. Thus, although memory B cells are sensitive to TLR agonists in vitro, TLR agonists alone appear to have little affect on B cell memory in vivo.
- Published
- 2008
37. Membrane heterogeneities in the formation of B cell receptor–Lyn kinase microclusters and the immune synapse
- Author
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Hae Won Sohn, Pavel Tolar, and Susan K. Pierce
- Subjects
Protein Conformation ,Immunology ,B-cell receptor ,Receptors, Antigen, B-Cell ,Biology ,Article ,Cell Line ,Immunological synapse ,Cell membrane ,Mice ,Membrane Microdomains ,LYN ,hemic and lymphatic diseases ,Fluorescence Resonance Energy Transfer ,medicine ,Animals ,Immunology and Allergy ,Src family kinase ,Lipid raft ,Research Articles ,Antigen Presentation ,B-Lymphocytes ,Cell Membrane ,Receptor Aggregation ,breakpoint cluster region ,Cell Biology ,Cell biology ,Antigens, Differentiation, B-Lymphocyte ,src-Family Kinases ,medicine.anatomical_structure ,Microscopy, Fluorescence ,Signal transduction ,Signal Transduction - Abstract
Antigen binding to the B cell receptors (BCRs) induces BCR clustering, phosphorylation of BCRs by the Src family kinase Lyn, initiation of signaling, and formation of an immune synapse. We investigated B cells as they first encountered antigen on a membrane using live cell high resolution total internal reflection fluorescence microscopy in conjunction with fluorescence resonance energy transfer. Newly formed BCR microclusters perturb the local membrane microenvironment, leading to association with a lipid raft probe. This early event is BCR intrinsic and independent of BCR signaling. Association of BCR microclusters with membrane-tethered Lyn depends on Lyn activity and persists as microclusters accumulate and form an immune synapse. Membrane perturbation and BCR–Lyn association correlate both temporally and spatially with the transition of microclustered BCRs from a “closed” to an “open” active signaling conformation. Visualization and analysis of the earliest events in BCR signaling highlight the importance of the membrane microenvironment for formation of BCR–Lyn complexes and the B cell immune synapse.
- Published
- 2008
38. The B Cell Receptor Governs the Subcellular Location of Toll-like Receptor 9 Leading to Hyperresponses to DNA-Containing Antigens
- Author
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Susan K. Pierce, Akanksha Chaturvedi, and David W. Dorward
- Subjects
Autophagosome ,Endosome ,B-cell receptor ,Immunology ,Receptors, Antigen, B-Cell ,Protein Serine-Threonine Kinases ,Biology ,Mice ,Phagosomes ,Animals ,Immunology and Allergy ,Antigens ,MOLIMMUNO ,Microscopy, Immunoelectron ,Receptor ,B-Lymphocytes ,breakpoint cluster region ,DNA ,Toll-Like Receptor 9 ,Cell biology ,Mice, Inbred C57BL ,Endocytic vesicle ,Infectious Diseases ,Mitogen-Activated Protein Kinases ,Signal transduction ,Spleen ,Signal Transduction - Abstract
SummarySynergistic engagement of the B cell receptor (BCR) and Toll-like receptor 9 (TLR9) in response to DNA-containing antigens underlies the production of many autoantibodies in systemic autoimmune diseases. However, the molecular basis of this synergistic engagement is not known. Given that these receptors are spatially segregated, with the BCR on the cell surface and TLR9 in endocytic vesicles, achieving synergy must involve unique mechanisms. We show that upon antigen binding, the BCR initiates signaling at the plasma membrane and continues to signal to activate MAP kinases as it traffics to autophagosome-like compartments. The internalized BCR signals through a phospholipase-D-dependent pathway to recruit TLR9-containing endosomes to the autophagosome via the microtubular network. The recruitment of TLR9 to the autophagosomes was necessary for hyperactivation of MAP kinases. This unique mechanism for BCR-induced TLR9 recruitment resulting in B cells hyperresponses may provide new targets for therapeutics for autoimmune diseases.
- Published
- 2008
- Full Text
- View/download PDF
39. Viewing the antigen-induced initiation of B-cell activation in living cells
- Author
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Hae Won Sohn, Pavel Tolar, and Susan K. Pierce
- Subjects
Antigen Presentation ,B-Lymphocytes ,biology ,Cell Membrane ,Immunology ,breakpoint cluster region ,Receptors, Antigen, B-Cell ,Lymphocyte Activation ,Major histocompatibility complex ,Cell biology ,medicine.anatomical_structure ,Antigen ,Live cell imaging ,hemic and lymphatic diseases ,Image Processing, Computer-Assisted ,biology.protein ,medicine ,Animals ,Humans ,Immunology and Allergy ,Receptor clustering ,Antigens ,Signal transduction ,Receptor ,B cell - Abstract
The binding of antigen to the B‐cell receptor (BCR) induces BCR clustering and signaling cascades that lead to the activation of a variety of genes associated with B‐cell activation. Over the last several years, our understanding of the molecular details of the BCR signaling pathways have been considerably advanced; what remains only poorly understood are the molecular events that initiate BCR clustering and how clustering leads to activation. Here, we review our progress using live cell imaging technologies to view the earliest events that follow the B cell's binding of antigen. We provide a model for BCR clustering and B‐cell activation that involves an intrinsic tendency of the BCR to cluster and does not require direct crosslinking of the BCR by multivalent antigens. We suggest that local membrane topology and lipid composition play key roles in BCR clustering and initiation of signaling. We believe that our model for B‐cell activation, in which receptor interactions with monovalent antigens on membrane surfaces lead to receptor clustering, may be highly relevant to the mechanisms by which other immune receptors cluster including the T‐cell receptor in response to monovalent peptide–major histocompatibility complex complexes.
- Published
- 2008
40. Live Cell Imaging Reveals that the Inhibitory FcγRIIB Destabilizes B Cell Receptor Membrane-Lipid Interactions and Blocks Immune Synapse Formation
- Author
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Hae Won Sohn, Susan K. Pierce, and Shiang-Jong Tzeng
- Subjects
Immunology ,B-cell receptor ,Receptors, Antigen, B-Cell ,Biology ,Cell Line ,Immunological synapse ,Mice ,Membrane Microdomains ,Live cell imaging ,hemic and lymphatic diseases ,Fluorescence Resonance Energy Transfer ,medicine ,Animals ,Immunology and Allergy ,Antigens ,Receptor ,Lipid raft ,B cell ,B-Lymphocytes ,Microscopy, Confocal ,Receptors, IgG ,breakpoint cluster region ,Cell biology ,Förster resonance energy transfer ,medicine.anatomical_structure ,lipids (amino acids, peptides, and proteins) - Abstract
The FcγRIIB is a potent regulator of BCR signaling and as such plays a decisive role in controlling autoimmunity. The use of advanced imaging technologies has provided evidence that the earliest events in Ag-induced BCR signaling include the clustering of the BCR, the selective and transient association of the clustered BCR with raft lipids, and the concentration of BCR clusters in an immune synapse. That lipid rafts play a role in FcγRIIB’s regulation of BCR signaling was suggested by recent studies showing that a lupus-associated loss of function mutation resulted in the receptor’s exclusion from lipid rafts and the failure to regulate BCR signaling. In this study, we provide evidence from both biochemical analyses and fluorescence resonance energy transfer in conjunction with both confocal and total internal reflection microscopy in living cells that the FcγRIIB, when coligated with the BCR, associates with lipid rafts and functions both to destabilize the association of the BCR with raft lipids and to block the subsequent formation of the B cell’s immune synapse. These results define new early targets of FcγRIIB inhibitory activity in the Ag-induced B cell activation pathway.
- Published
- 2008
41. Targeting glutamine metabolism rescues mice from late-stage cerebral malaria
- Author
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Susan K. Pierce, Takele Yazew, Tuan M. Tran, Chen Feng Qi, Geoffrey T. Hart, Sara E. Hamilton, Michael Waisberg, Chen Fang Lee, Mirna Pena, Ying-Chun Lo, Munir Akkaya, Jonathan D. Powell, Ann S. Kim, Louis H. Miller, and Emile B. Gordon
- Subjects
Multidisciplinary ,Effector ,Glutamine ,Diazooxonorleucine ,Malaria, Cerebral ,Biology ,Blood–brain barrier ,Antimalarials ,Mice ,medicine.anatomical_structure ,Cerebral Malaria ,Blood-Brain Barrier ,Case fatality rate ,Immunology ,medicine ,Cytotoxic T cell ,Animals ,Malaria, Falciparum ,Complication ,CD8 - Abstract
The most deadly complication of Plasmodium falciparum infection is cerebral malaria (CM) with a case fatality rate of 15-25% in African children despite effective antimalarial chemotherapy. There are no adjunctive treatments for CM, so there is an urgent need to identify new targets for therapy. Here we show that the glutamine analog 6-diazo-5-oxo-L-norleucine (DON) rescues mice from CM when administered late in the infection a time at which mice already are suffering blood-brain barrier dysfunction, brain swelling, and hemorrhaging accompanied by accumulation of parasite-specific CD8(+) effector T cells and infected red blood cells in the brain. Remarkably, within hours of DON treatment mice showed blood-brain barrier integrity, reduced brain swelling, decreased function of activated effector CD8(+) T cells in the brain, and levels of brain metabolites that resembled those in uninfected mice. These results suggest DON as a strong candidate for an effective adjunctive therapy for CM in African children.
- Published
- 2015
42. Inhibiting the Mammalian Target of Rapamycin Blocks the Development of Experimental Cerebral Malaria
- Author
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Michael Waisberg, Geoffrey T. Hart, Jeff Skinner, Susan K. Pierce, Mirna Pena, Louis H. Miller, Chen Feng Qi, Takele Yazew, Tuan M. Tran, Severin Zinöcker, Munir Akkaya, and Emile B. Gordon
- Subjects
Malaria, Cerebral ,VDP::Medical immunology: 716 ,Disease ,Microbiology ,VDP::Medisinsk immunologi: 716 ,Pathogenesis ,Mice ,Immune system ,Virology ,parasitic diseases ,medicine ,Animals ,PI3K/AKT/mTOR pathway ,Sirolimus ,business.industry ,Gene Expression Profiling ,TOR Serine-Threonine Kinases ,Brain ,medicine.disease ,Survival Analysis ,QR1-502 ,Malaria ,Cerebral Malaria ,Infectious disease (medical specialty) ,Immunology ,business ,CD8 ,Research Article - Abstract
Malaria is an infectious disease caused by parasites of several Plasmodium spp. Cerebral malaria (CM) is a common form of severe malaria resulting in nearly 700,000 deaths each year in Africa alone. At present, there is no adjunctive therapy for CM. Although the mechanisms underlying the pathogenesis of CM are incompletely understood, it is likely that both intrinsic features of the parasite and the human host’s immune response contribute to disease. The kinase mammalian target of rapamycin (mTOR) is a central regulator of immune responses, and drugs that inhibit the mTOR pathway have been shown to be antiparasitic. In a mouse model of CM, experimental CM (ECM), we show that the mTOR inhibitor rapamycin protects against ECM when administered within the first 4 days of infection. Treatment with rapamycin increased survival, blocked breakdown of the blood-brain barrier and brain hemorrhaging, decreased the influx of both CD4+ and CD8+ T cells into the brain and the accumulation of parasitized red blood cells in the brain. Rapamycin induced marked transcriptional changes in the brains of infected mice, and analysis of transcription profiles predicted that rapamycin blocked leukocyte trafficking to and proliferation in the brain. Remarkably, animals were protected against ECM even though rapamycin treatment significantly increased the inflammatory response induced by infection in both the brain and spleen. These results open a new avenue for the development of highly selective adjunctive therapies for CM by targeting pathways that regulate host and parasite metabolism., IMPORTANCE Malaria is a highly prevalent infectious disease caused by parasites of several Plasmodium spp. Malaria is usually uncomplicated and resolves with time; however, in about 1% of cases, almost exclusively among young children, malaria becomes severe and life threatening, resulting in nearly 700,000 deaths each year in Africa alone. Among the most severe complications of Plasmodium falciparum infection is cerebral malaria with a fatality rate of 15 to 20%, despite treatment with antimalarial drugs. Cerebral malaria takes a second toll on African children, leaving survivors at high risk of debilitating neurological defects. At present, we have no effective adjunctive therapies for cerebral malaria, and developing such therapies would have a large impact on saving young lives in Africa. Here we report results that open a new avenue for the development of highly selective adjunctive therapies for cerebral malaria by targeting pathways that regulate host and parasite metabolism.
- Published
- 2015
43. Notes on facultative predation in Prosimulium larvae (Diptera: Simuliidae) in alpine and subalpine streams in Colorado
- Author
-
Robert Hancock, Layla Al-Shaer, David Larson, and Allison K. Pierce
- Subjects
Larva ,Facultative ,Colorado ,Obligate ,Ecology ,fungi ,Public Health, Environmental and Occupational Health ,Cannibalism ,General Medicine ,STREAMS ,Biology ,biology.organism_classification ,Predation ,Lakes ,Rivers ,Insect Science ,Predatory Behavior ,Montane ecology ,Animals ,Simuliidae ,Black fly ,Ecology, Evolution, Behavior and Systematics - Abstract
Although it is widely accepted that black fly larvae employ filter feeding as their primary mode of nutrient intake, other forms of food acquisition, such as predation, may be more prevalent than previously realized. It has been suggested that environments where particulate matter is low, such as high-elevation seasonal streams, may drive predatory behavior in black fly larvae. Relatively little is known about the frequency at which larvae prey on other organisms or if predation may be obligate in some species. In order to supplement the idea that larval black fly predation may be a common method of feeding under certain conditions, a preliminary survey of predation by Prosimulium larvae was conducted in order to assess predation frequency at high-elevation sites (3,200 m) in the Colorado Rocky Mountains. Larvae were sampled from alpine and subalpine locations, and their gut content analysis revealed evidence of facultative predation and possible cannibalism. Evidence of predation was observed in all but 1 Prosimulium species collected. Predation frequency was highest in the North Fork Snake River headwater location, a small tributary stream of the Snake River in central Colorado. This survey suggests that further inquiry into predatory behavior of black fly larvae should be conducted to determine the mechanisms, behavior, and ecological impact of this understudied feeding strategy.
- Published
- 2015
44. Ups and downs in the search for a Herpes simplex virus vaccine
- Author
-
Silvia Bolland and Susan K. Pierce
- Subjects
Simplexvirus ,food.ingredient ,QH301-705.5 ,Science ,viruses ,Biology ,medicine.disease_cause ,General Biochemistry, Genetics and Molecular Biology ,Mice ,food ,Immunity ,Virology ,vaccine ,antibody ,medicine ,Glycoprotein D ,Animals ,Biology (General) ,mouse ,Microbiology and Infectious Disease ,General Immunology and Microbiology ,General Neuroscience ,Viral Vaccine ,Viral Vaccines ,General Medicine ,HSV-2 ,immunity ,Herpes simplex virus ,Infectious disease (medical specialty) ,Immunology ,biology.protein ,Medicine ,Antibody ,Insight - Abstract
Modified herpes simplex viruses that are unable to produce glycoprotein D may make effective vaccines.
- Published
- 2015
45. FISH labeling reveals a horizontally transferred algal (Vaucheria litorea) nuclear gene on a sea slug (Elysia chlorotica) chromosome
- Author
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Julie A. Schwartz, Nicholas E. Curtis, and Sidney K. Pierce
- Subjects
animal structures ,Nuclear gene ,Gene Transfer, Horizontal ,Slug ,fungi ,Algal Proteins ,Gastropoda ,Biology ,biology.organism_classification ,Molecular biology ,Chromosomes ,law.invention ,Sea slug ,Transcriptome ,Real-time polymerase chain reaction ,law ,Elysia chlorotica ,Animals ,General Agricultural and Biological Sciences ,Polymerase chain reaction ,In Situ Hybridization, Fluorescence ,Stramenopiles ,Vaucheria litorea - Abstract
The horizontal transfer of functional nuclear genes, coding for both chloroplast proteins and chlorophyll synthesis, from the food alga Vaucheria litorea to the sea slug Elysia chlorotica has been demonstrated by pharmacological, polymerase chain reaction (PCR), real time PCR (qRT-PCR), and transcriptome sequencing experiments. However, partial genomic sequencing of E. chlorotica larvae failed to find evidence for gene transfer. Here, we have used fluorescent in situ hybridization to localize an algal nuclear gene, prk, found in both larval and adult slug DNA by PCR and in adult RNA by transcriptome sequencing and RT-PCR. The prk probe hybridized with a metaphase chromosome in slug larvae, confirming gene transfer between alga and slug.
- Published
- 2015
46. The initiation of antigen-induced B cell antigen receptor signaling viewed in living cells by fluorescence resonance energy transfer
- Author
-
Hae Won Sohn, Susan K. Pierce, and Pavel Tolar
- Subjects
Conformational change ,Immunology ,B-cell receptor ,Receptors, Antigen, B-Cell ,Syk ,Biology ,Mice ,Antigen ,hemic and lymphatic diseases ,Fluorescence Resonance Energy Transfer ,Animals ,Syk Kinase ,Immunology and Allergy ,Src family kinase ,Antigens ,Phosphorylation ,B-Lymphocytes ,Enzyme Precursors ,T-cell receptor ,Intracellular Signaling Peptides and Proteins ,breakpoint cluster region ,Protein-Tyrosine Kinases ,Protein Structure, Tertiary ,Cell biology ,src-Family Kinases ,Signal transduction ,Signal Transduction - Abstract
Binding of antigen to the B cell antigen receptor (BCR) triggers signaling that ultimately leads to B cell activation. Using quantitative fluorescence resonance energy transfer imaging, we provide evidence here that the BCR is a monomer on the surface of resting cells. Binding of multivalent antigen clustered the BCR, resulting in the simultaneous phosphorylation of and a conformational change in the BCR cytoplasmic domains from a closed to an open form. Notably, the open conformation required immunoreceptor tyrosine-activation motif and continuous Src family kinase activity but not binding of the kinase Syk. Thus, the initiation of BCR signaling is a very dynamic process accompanied by reversible conformational changes induced by Src family kinase activity.
- Published
- 2005
47. The B Cell Inhibitory Fc Receptor Triggers Apoptosis by a Novel c-Abl Family Kinase-dependent Pathway
- Author
-
Susan K. Pierce, Shiang-Jong Tzeng, Kazunori Inabe, Tomohiro Kurosaki, and Silvia Bolland
- Subjects
Cytoplasm ,Amino Acid Motifs ,Blotting, Western ,B-cell receptor ,Fc receptor ,Receptors, Antigen, B-Cell ,Apoptosis ,Receptors, Fc ,Biochemistry ,Membrane Potentials ,Mice ,Antigens, CD ,Cell Line, Tumor ,hemic and lymphatic diseases ,In Situ Nick-End Labeling ,Animals ,Immunoprecipitation ,Antigens ,Phosphorylation ,Proto-Oncogene Proteins c-abl ,Receptor ,Molecular Biology ,B-Lymphocytes ,ABL ,biology ,Chemistry ,Cell Cycle ,Receptors, IgG ,breakpoint cluster region ,Cytochromes c ,DNA ,Cell Biology ,Protein-Tyrosine Kinases ,Hematopoietic Stem Cells ,Phosphoric Monoester Hydrolases ,Cell biology ,Caspases ,Mitochondrial Membranes ,biology.protein ,Signal transduction ,Immunoreceptor tyrosine-based inhibitory motif ,Chickens ,Tyrosine kinase ,Signal Transduction - Abstract
The inhibitory Fc receptors function to regulate the antigen-driven activation and expansion of lymphocytes. In B cells, the Fc gammaRIIB1 is a potent inhibitor of B cell antigen receptor (BCR) signaling when coligated to the BCR by engagement of antigen-containing immune complexes. Inhibition is mediated by the recruitment of the inositol phosphatase, SHIP, to the Fc gammaRIIB1 phosphorylated tyrosine-based inhibitory motif (ITIM). Here we show that BCR-independent aggregation of the Fc gammaRIIB1 transduces an ITIM- and SHIP-independent proapoptotic signal that is dependent on members of the c-Abl tyrosine kinase family. These results define a novel Abl family kinase-dependent Fc gammaRIIB1 signaling pathway that functions independently of the BCR in controlling antigen-driven B cell responses.
- Published
- 2005
48. CD21/CD19 Coreceptor Signaling Promotes B Cell Survival during Primary Immune Responses
- Author
-
Ming Zhang, Robert A. Barrington, Anu Cherukuri, Thomas L. Rothstein, Nichol E. Holodick, Helena Jonsson, Michael C. Carroll, Xuemei Zhong, and Susan K. Pierce
- Subjects
Adoptive cell transfer ,Cell Survival ,Antigens, CD19 ,Immunology ,B-cell receptor ,Naive B cell ,CASP8 and FADD-Like Apoptosis Regulating Protein ,Apoptosis ,chemical and pharmacologic phenomena ,CD19 ,Mice ,Antigen ,hemic and lymphatic diseases ,medicine ,Animals ,Immunology and Allergy ,fas Receptor ,B cell ,B-Lymphocytes ,biology ,Intracellular Signaling Peptides and Proteins ,Acquired immune system ,Cell biology ,Mice, Inbred C57BL ,medicine.anatomical_structure ,Complement C3d ,Receptors, Complement 3b ,biology.protein ,Muramidase ,Receptors, Complement 3d ,Antibody ,Signal Transduction - Abstract
The adaptive immune response is tightly regulated to limit responding cells in an Ag-specific manner. On B cells, coreceptors CD21/CD19 modulate the strength of BCR signals, potentially influencing cell fate. The importance of the CD95 pathway was examined in response of B cells to moderate affinity Ag using an adoptive transfer model of lysozyme-specific Ig transgenic (HEL immunoglobulin transgene (MD4) strain) B cells. Although adoptively transferred Cr2+/+ MD4 B cells are activated and persist within splenic follicles of duck egg lysozyme-immunized mice, Cr2−/− MD4 B cells do not. In contrast, Cr2−/− MD4 lpr B cells persist after transfer, suggesting that lack of CD21/CD35 signaling results in CD95-mediated elimination. Cr2 deficiency did not affect CD95 levels, but cellular FLIP (c-FLIP) protein and mRNA levels were reduced 2-fold compared with levels in Cr2+/+ MD4 B cells. In vitro culture with Cr2+/+ MD4 B cells demonstrated that equimolar amounts of rHEL-C3d3 were more effective than hen egg lysozyme alone in up-regulating c-FLIP levels and for protection against CD95-mediated apoptosis. Collectively, this study implies a mechanism for regulating B cell survival in vivo whereby the strength of BCR signaling (including coreceptor) determines c-FLIP levels and protection from CD95-induced death.
- Published
- 2005
49. Autoantigens act as tissue-specific chemoattractants
- Author
-
Olivera J. Finn, Susan K. Pierce, Joost J. Oppenheim, Michelle L. Dykstra, O. M. Zack Howard, Rachel R. Caspi, Omanand Koul, Hui Fang Dong, Roland Martin, Casey A. Carlos, and Paul H. Plotz
- Subjects
Leukocyte migration ,Chemokine ,Immunology ,Autoantigens ,CXCR5 ,Autoimmune Diseases ,Mice ,Immune system ,Antigens, Neoplasm ,Neoplasms ,medicine ,Animals ,Humans ,Immunology and Allergy ,CXC chemokine receptors ,Chemotactic Factors ,biology ,Experimental autoimmune encephalomyelitis ,Autoantibody ,Dendritic Cells ,Cell Biology ,medicine.disease ,Chemotaxis, Leukocyte ,Leukocytes, Mononuclear ,biology.protein ,CC chemokine receptors - Abstract
We have investigated the chemoattractant properties of self-antigens associated with autoimmune diseases and solid tumors. Many autoantigens induced leukocyte migration, especially by immature dendritic cells (iDC) by interacting with various chemoattractant Gi-protein-coupled receptors (GiPCR). Our initial observation that myositis-associated autoantigens, histidyl-tRNA synthetase and asparaginyl-tRNA synthetase, were chemotactic for CC chemokine receptor 5 (CCR5)- and CCR3-expressing leukocytes, while other nonautoantigenic aminoacyl-tRNA synthesases were not, suggested that only self-antigens capable of interacting with receptors on antigen-presenting cells were immunogenic. We next determined that self-antigens associated with autoimmune diseases, e.g., multiple sclerosis or experimental autoimmune encephalomyelitis, type I diabetes, scleroderma, systemic lupus erythematosus, autoimmune uveitis, or experimental autoimmune uveitis (EAU), were chemotactic for GiPCR expressed by iDC. The majority of autoantigens were DC chemoattractants at 10–100 ng/ml, but did not induce DC maturation until they reached 1000-fold higher concentrations. Interphotoreceptor retinoid-binding protein and retinal arrestin (S-antigen) are targets of autoantibodies in human uveitis and are chemotactic for CXC chemokine receptor 5 (CXCR5)- and/or CXCR3-expressing iDC. However, although S-antigen does not induce EAU in wild-type mice, it is nevertheless a chemoattractant for murine iDC. These unexpected observations suggested that the chemotactic activity of these tissue-specific self-antigens could be involved in promotion of tissue repair and restoration. Thus, the primary role of autoantigens may be to alert the immune system to danger signals from invaded and damaged tissues to facilitate repair, and autoimmune responses subsequently develop only in subjects with impaired immunoregulatory function.
- Published
- 2005
50. The Tetraspanin CD81 Is Necessary for Partitioning of Coligated CD19/CD21-B Cell Antigen Receptor Complexes into Signaling-Active Lipid Rafts
- Author
-
Anu Cherukuri, Stephen R. Brooks, Shoshana Levy, Robert H. Carter, Tsipi Shoham, T. Hae Won Sohn, and Susan K. Pierce
- Subjects
Male ,Tetraspanins ,Recombinant Fusion Proteins ,Antigens, CD19 ,Immunology ,B-cell receptor ,B-Lymphocyte Subsets ,Down-Regulation ,Receptors, Antigen, B-Cell ,Mice, Transgenic ,Nerve Tissue Proteins ,chemical and pharmacologic phenomena ,Biology ,Ligands ,CD19 ,Tetraspanin 28 ,Mice ,Membrane Microdomains ,Adjuvants, Immunologic ,Tetraspanin ,Antigens, CD ,immune system diseases ,hemic and lymphatic diseases ,medicine ,Animals ,Immunology and Allergy ,Receptor ,Lipid raft ,B cell ,Cell Line, Transformed ,Mice, Inbred BALB C ,breakpoint cluster region ,Membrane Proteins ,hemic and immune systems ,Cell biology ,medicine.anatomical_structure ,Mice, Inbred CBA ,biology.protein ,Female ,Receptors, Complement 3d ,lipids (amino acids, peptides, and proteins) ,Signal Transduction ,CD81 - Abstract
Tetraspanins have been hypothesized to facilitate the organization of functional multimolecular membrane complexes. In B cells the tetraspanin CD81 is a component of the CD19/CD21 complex. When coligated to the B cell Ag receptor (BCR), the CD19/CD21 complex significantly enhances BCR signaling in part by prolonging the association of the BCR with signaling-active lipid rafts. In this study CD81 is shown to associate with lipid rafts upon coligation of the BCR and the CD19/CD21 complex. Using B cells from CD81-deficient mice we demonstrate that in the absence of CD81, coligated BCR and CD19/CD21 complexes fail to partition into lipid rafts and enhance BCR signaling from rafts. Furthermore, a chimeric CD19 protein that associates only weakly if at all with CD81 fails to promote the association of coligated BCR with lipid rafts. The requirement for CD81 to promote lipid raft association may define a novel mechanism by which tetraspanins function as molecular facilitators of signaling receptors.
- Published
- 2004
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