Proteomic identification of the contents of small extracellular vesicles from in vivo Plasmodium yoelii infection.

Small extracellular vesicles, including exosomes, are formed by the endocytic pathway and contain genetic and protein material which reflect the contents of their cells of origin. These contents have a role in vesicle-mediated information transfer, as well as physiological and pathological functions. Thus, these vesicles are of great interest as therapeutic targets, or as vehicles for immunomodulatory control.

Identification of the Glycan Binding Profile of Human and Rodent Sporozoites.

The transmission of spp. sporozoites to the mammalian host is the first step in the initiation of the mosquito-borne disease known as malaria. The exact route of transmission from the bloodstream to the liver is still not clearly elucidated, and identification of the host glycan structures bound by the sporozoites may inform as to which host cells are involved.

A population of CD4CD38 T cells correlates with disease severity in patients with acute malaria.

Objective: CD4 T cells are critical mediators of immunity to spp. infection, but their characteristics during malarial episodes and immunopathology in naturally infected adults are poorly defined. Flow cytometric analysis of PBMCs from patients with either or malaria revealed a pronounced population of CD4 T cells co-expressing very high levels of CD4 and CD38 we have termed CD4CD38 T cells.

Chimeric Virus-Like Particles and Capsomeres Induce Similar CD8 T Cell Responses but Differ in Capacity to Induce CD4 T Cell Responses and Antibody Responses.

Despite extensive research, the development of an effective malaria vaccine remains elusive. The induction of robust and sustained T cell and antibody response by vaccination is an urgent unmet need. Chimeric virus-like particles (VLPs) are a promising vaccine platform.

Chimeric Murine Polyomavirus Virus-Like Particles Induce Antigen-Specific CD8 T Cell and Antibody Responses.

An effective vaccine against the parasite is likely to require the induction of robust antibody and T cell responses. Chimeric virus-like particles are an effective vaccine platform for induction of antibody responses, but their capacity to induce robust cellular responses and cell-mediated protection against pathogen challenge has not been established. To evaluate this, we produced chimeric constructs using the murine polyomavirus structural protein with surface-exposed CD8 or CD4 T cell or B cell repeat epitopes derived from the circumsporozoite protein, and assessed immunogenicity and protective capacity in a murine model.

Defined Small Molecules Produced by Himalayan Medicinal Plants Display Immunomodulatory Properties.

Plant-derived compounds that modulate the immune responses are emerging as frontline treatment agents for cancer, infectious diseases and autoimmunity. Herein we have isolated 40 phytochemicals from five Bhutanese medicinal plants-, , , and -and tested 14 purified compounds for their immunomodulatory properties using a murine dendritic cell (DC) line, and cytotoxicity against a human cholangiocyte cell line using xCELLigence real time cell monitoring. These compounds were: pseudaconitine, 14-veratryolpseudaconitine, 14--acetylneoline, linalool oxide acetate, ()-spiroether, luteolin, luteolin-7--β-d-glucopyranoside, protopine, ochrobirine, scoulerine, capnoidine, isomyristicin, bergapten, and isoimperatorin.

A Balanced Proinflammatory and Regulatory Cytokine Signature in Young African Children Is Associated With Lower Risk of Clinical Malaria.

Background: The effect of timing of exposure to first Plasmodium falciparum infections during early childhood on the induction of innate and adaptive cytokine responses and their contribution to the development of clinical malaria immunity is not well established.

Methods: As part of a double-blind, randomized, placebo-controlled trial in Mozambique using monthly chemoprophylaxis with sulfadoxine-pyrimethamine plus artesunate to selectively control timing of malaria exposure during infancy, peripheral blood mononuclear cells collected from participants at age 2.5, 5.

High production of pro-inflammatory cytokines by maternal blood mononuclear cells is associated with reduced maternal malaria but increased cord blood infection.

Background: Increased susceptibility to malaria during pregnancy is not completely understood. Cellular immune responses mediate both pathology and immunity but the effector responses involved in these processes have not been fully characterized. Maternal and fetal cytokine and chemokine responses to malaria at delivery, and their association with pregnancy and childhood outcomes, were investigated in 174 samples from a mother and child cohort from Mozambique.

Influence of Physicochemical Properties of Lipopeptide Adjuvants on the Immune Response: A Rationale for Engineering a Potent Vaccine.

Adjuvant development and understanding the physicochemical properties of particles and interpreting the subsequent immunological responses is a challenge faced by many researchers in the vaccine field. We synthesized and investigated the physicochemical properties and immunogenicity of a library of multiple epitope self-adjuvant lipopeptides in a novel asymmetric arrangement. Vaccine candidates were synthesized using a combination of solid-phase peptide synthesis and copper-mediated click chemistry.

Dichotomous miR expression and immune responses following primary blood-stage malaria.

Clinical responses to infection or vaccination and the development of effective immunity are characterized in humans by a marked interindividual variability. To gain an insight into the factors affecting this variability, we used a controlled human infection system to study early immune events following primary infection of healthy human volunteers with blood-stage Plasmodium falciparum malaria. By day 4 of infection, a dichotomous pattern of high or low expression of a defined set of microRNAs (miRs) emerged in volunteers that correlated with variation in parasite growth rate.

Polyfunctional and IFN- monofunctional human CD4 T cell populations are molecularly distinct.

Pathogen-specific polyfunctional T cell responses have been associated with favorable clinical outcomes, but it is not known whether molecular differences exist between polyfunctional and monofunctional cytokine-producing T cells. Here, we report that polyfunctional CD4 T cells induced during (. ) blood-stage infection in humans have a unique transcriptomic profile compared with IFN-γ monofunctional CD4 T cells and, thus, are molecularly distinct.

Reduced Plasmodium Parasite Burden Associates with CD38+ CD4+ T Cells Displaying Cytolytic Potential and Impaired IFN-γ Production.

Unlabelled: Using a unique resource of samples from a controlled human malaria infection (CHMI) study, we identified a novel population of CD4+ T cells whose frequency in the peripheral blood was inversely correlated with parasite burden following P. falciparum infection. These CD4+ T cells expressed the multifunctional ectoenzyme CD38 and had unique features that distinguished them from other CD4+ T cells.

Chemically Attenuated Blood-Stage Plasmodium yoelii Parasites Induce Long-Lived and Strain-Transcending Protection.

The development of a vaccine is essential for the elimination of malaria. However, despite many years of effort, a successful vaccine has not been achieved. Most subunit vaccine candidates tested in clinical trials have provided limited efficacy, and thus attenuated whole-parasite vaccines are now receiving close scrutiny.

Quantitative assessment of the functional plasticity of memory CD8(+) T cells.

While the functional plasticity of memory CD4(+) T cells has been studied extensively, less is known about this property in memory CD8(+) T cells. Here, we report the direct measurement of plasticity by paired daughter analysis of effector and memory OT-I CD8(+) T cells primed in vivo with ovalbumin. Naïve, effector, and memory OT-I cells were isolated and activated in single-cell culture; then, after the first division, their daughter cells were transferred to new cultures with and without IL-4; expression of IFN-γ and IL-4 mRNAs was measured 5 days later in the resultant subclones.

Systematic evaluation of self-adjuvanting lipopeptide nano-vaccine platforms for the induction of potent CD8(+) T-cell responses.

Aim: Systematically evaluate lipid core peptide vaccine delivery platforms to identify core features promoting strong CD8(+) T-cell responses.

Materials & Methods: Three different self-adjuvanting lipid core peptide nanovaccines each comprising four copies of the dominant ovalbumin CD8(+) T-cell epitope and varying in the utilization of a polylysine or glucose core with 2-amino-hexadecanoic acid (C16) or 2-amino-dodecanoic acid (C12) lipids were synthesized. Vaccines were tested for ability to induce CD8(+) T-cell responses and inhibit tumor growth in vivo.

Highly sensitive quantitative real-time PCR for the detection of Plasmodium liver-stage parasite burden following low-dose sporozoite challenge.

The pre-erythrocytic stages of Plasmodium spp. are increasingly recognised as ideal targets for prophylactic vaccines and drug treatments. Intense research efforts in the last decade have been focused on in vitro culture and in vivo detection and quantification of liver stage parasites to assess the effects of candidate vaccines or drugs.

Subcutaneous cholera toxin exposure induces potent CD103⁺ dermal dendritic cell activation and migration.

CD103⁺ dermal dendritic cells (dDCs) are a recently described DC subset of the skin shown to be the principal migratory DCs capable of efficiently cross-presenting antigens and activating CD8⁺ T cells. Harnessing their activity would promote vaccine efficacy, but it has been unclear how this can be achieved. We tested a panel of adjuvants for their ability to affect dDCs.

Evaluation of approaches to identify the targets of cellular immunity on a proteome-wide scale.

Background: Vaccine development against malaria and other complex diseases remains a challenge for the scientific community. The recent elucidation of the genome, proteome and transcriptome of many of these complex pathogens provides the basis for rational vaccine design by identifying, on a proteome-wide scale, novel target antigens that are recognized by T cells and antibodies from exposed individuals. However, there is currently no algorithm to effectively identify important target antigens from genome sequence data; this is especially challenging for T cell targets.

High-throughput multi-parameter flow-cytometric analysis from micro-quantities of plasmodium-infected blood.

Despite significant technological and conceptual advances over the last century, evaluation of the efficacy of anti-malarial vaccines or drugs continues to rely principally on direct microscopic visualisation of parasites on thick and/or thin Giemsa-stained blood smears. This requires technical expertise of the microscopist, is highly subjective and error-prone, and does not account for aberrations such as anaemia. Many published methods have shown that flow cytometric analysis of blood is a highly versatile method that can readily detect nucleic acid-stained parasitised red blood cells within cultured cell populations and in ex-vivo samples.

IFN-gamma inhibits IL-4-induced type 2 cytokine expression by CD8 T cells in vivo and modulates the anti-tumor response.

Activation of naive CD8 T cells in vitro in the presence of IL-4 induces type 2 cytokine expression, loss of CD8 expression, and reduced cytolytic potential. This represents a major shift from the canonical phenotype of effector CD8 T cells. It has not been established, however, whether IL-4 can induce comprehensive type 2 cytokine expression by CD8 T cells in vivo, nor whether the effects of IL-4 on type 2 cytokine production by CD8 T cells can be inhibited by IFN-gamma.

Interferon-gamma and interleukin-4 reciprocally regulate CD8 expression in CD8+ T cells.

The CD8 co-receptor can modulate CD8(+) T cell function through its contributions to T cell receptor (TCR) binding and signaling. Here we show that IFN-gamma and IL-4 exert opposing effects on the expression of CD8alpha mRNA and surface CD8 protein during CD8(+) T cell activation. IL-4 caused down-regulation of surface CD8 on ovalbumin (OVA)(257-264)-specific TCR-transgenic OT-I CD8(+) T cells activated with OVA(257-264)-coated antigen presenting cells or polyclonal stimuli, and on wild type CD8(+) T cells activated with polyclonal stimuli.

Branched and linear lipopeptide vaccines have different effects on primary CD4+ and CD8+ T-cell activation but induce similar tumor-protective memory CD8+ T-cell responses.

We compared murine T-cell responses to synthetic lipopeptide vaccines in which the TLR2 ligand Pam(2)Cys was attached to co-linear CD4+ and CD8+ T-cell epitopes of ovalbumin (OVA) in a linear or branched configuration. Mice received OVA-specific transgenic CD8+ and CD4+ T-cells followed by one injection of vaccine. Although the branched lipopeptide was more potent in activating OVA-specific CD4+ and CD8+ T-cells in the primary response, both vaccines induced cytolytic T lymphocytes (CTL) that expressed perforin, granzyme A-C, and IFN-gamma mRNAs and conferred long-term protection of most mice against challenge with OVA-expressing tumor cells.

Tumor-derived interleukin-4 reduces tumor clearance and deviates the cytokine and granzyme profile of tumor-induced CD8+ T cells.

An interleukin (IL)-4-containing tumor environment is reported to be beneficial for immune clearance of tumor cells in vivo; however, the effect of IL-4 on the effector CD8+ T cells contributing to tumor clearance is not well defined. We have used the immunogenic HLA-CW3-expressing P815 (P.CW3) mastocytoma and investigated whether IL-4 expression by the tumor affects tumor clearance and, if so, whether it alters the tumor-induced Vbeta10+ CD8+ T-cell response.