Infection-induced resistance to experimental cerebral malaria
Ontology highlight
ABSTRACT: Cerebral malaria (CM) is one of the most severe complications of malaria infection. There is evidence that repeated parasite exposure promotes resistance against CM, as indicated by the low incidence of CM in adults in malaria-endemic regions. However, the immunological basis of this infection-induced resistance remains poorly understood. Here, a microarray study done utilising the tractable Plasmodium berghei ANKA model of experimental cerebral malaria (ECM), we show that three rounds of infection and drug-cure protects against the development of ECM during a subsequent fourth infection.
Project description:Cerebral Malaria (HCM) is a serious neurological complication caused by Plasmodium falciparum infection. Currently the only treatment for HCM is the provision of anti-malarial drugs; however, such treatment by itself often fails to prevent death or development of neurological sequelae. To identify new potential adjunct treatments for HCM, we performed a non-biased whole brain transcriptomic time-course analysis of anti-malarial drug chemotherapy of murine experimental CM (ECM).
Project description:Cerebral malaria (CM) is a severe complication of Plasmodium falciparum infection, predominantly experienced by children and non-immune adults, which results in great mortality and long-term sequelae. Recent reports based on histology of post-mortem brain tissue suggest that CM may be the common end point for a range of syndromes. Here, we have analysed the gene expression profiles in brain tissue taken from experimental CM (ECM)-susceptible, Plasmodium berghei ANKA (PbA)-infected C57BL/6 (B6) and CBA/CaH (CBA) mice with ECM. Gene expression profiles were largely heterogeneous between the two ECM-susceptible strains. These results, combined with experimental data, support the existence of distinct pathogenic pathways in CM. Experiment Overall Design: C57BL/6 and CBA/CaH mice were infected with 10e5 Plasmodium berghei ANKA-infected RBCs and monitored for ECM development. At onset of ECM symptoms, infected mice and naive controls were culled, perfused (in order to remove non-adherent circulating cells), and brains were removed. Total RNA was extracted from these brains and pooled (n=6 mice/ group). Pooled RNA samples were converted to cDNA and antisense cRNA, labelled and hybridized to GeneChip Mouse Genome 430 2.0 Arrays (Affymetrix, Surrey Hills, Australia). Arrays were scanned using the GeneChip Scanner 3000 (Affymetrix) and GeneChip Operating Software v1.1.1 (Affymetrix). Normalisation and initial analyses were carried out in GeneSpring v7 (Agilent Technologies). Values below 0.01 were set to 0.01. Each measurement was divided by the 50th percentile of all measurements in that sample. The data was filtered for genes flagged as present, which had at least an expression level of 50. Following this, a threshold of 2.5 fold up-regulation or down-regulation of genes differentially expressed during ECM was set.
Project description:Cerebral malaria (CM) is a severe complication of a Plasmodium falciparum infection and is still responsible for a high number of deaths and long term disabilities in children in sub-Saharan Africa. The pathogenesis of this syndrome remains incompletely understood but a number of mechanisms and effectors have been proposed, including plasma microparticles (MP). These submicron vesicles released by potentially all cells carry proteins and nucleic acids derived from the mother cell. In CM, their numbers are increased in patients’ circulation and, in the mouse model, they can be localised within inflamed vessels, suggesting their involvement in vascular damage. In the present work we define, for the first time, the protein cargo of MP during experimental cerebral malaria (ECM) with the overarching hypothesis that characterising this content could help in better understand CM pathogenesis. Using qualitative and quantitative high-throughput proteomics we compared MP proteins from non-infected mice and mice infected with P. berghei ANKA at two different stages of infection, i.e., pre-clinical phase and full blown syndrome. Overall, we identified 368 proteins, 60 of which were differentially expressed, as determined by quantitative comparison using the TMT® isobaric labelling. The analysis with Ingenuity® IPA highlighted important networks significantly represented among the proteins over-expressed (n=42) or identified only (n=21) in ECM, comprising mechanisms already proposed to be involved in CM, such as endothelial activation. Two proteins of interest, carbonic anhydrase I (CA-I) and S100A8, were verified by western blot on newly collected MP samples from DBA/1 (n=16) and C57BL/6 (n=8) mice, and confirmed to be associated with ECM MP. These results demonstrate that MP protein cargo represents a novel ECM pathogenic trait to consider in the understanding of CM pathogenesis. The identification of the cellular source of MP containing proteins associated to the disease state will contribute to further understanding their involvement in CM.
Project description:Cerebral malaria (CM) is a leading cause of death in the world. Better understanding of the pathogenesis of this disease is critical for the development of novel therapies. In this work, we investigated temporal gene expression profiles in the brains of CM-susceptible and CM-resistant mice during infection with P. Berghia ANKA (PbA). In this model of CM, susceptible mice develop neurological signs by day 6 post infection while resistant mice do not develop neurological manifestations during malarial infection. Experiment Overall Design: C57/B6 (CM-susceptible) and Balb/C (CM-resistant) mice were infected with PbA. Gene expression profiles from whole brains were obtained at day 0 (uninfected), day 1, day 3, and day 6.
Project description:Microarray analyses allow the identification and assessment of molecular signatures in whole tissues undergoing pathological processes. To better understand cerebral malaria pathogenesis, we investigated intra-cerebral gene-expression profiles in well-defined genetically cerebral malaria-resistant (CM-R) and CM-susceptible (CM-S) mice, upon infection by Plasmodium berghei ANKA. We investigated mouse transcriptional responses prior to infection, and at early and late stages of infection by use of cDNA microarrays. Through a rigorous statistical approach with multiple testing corrections, we showed that P. berghei ANKA significantly altered brain gene expression in CM-R (BALB/c), and in CM-S (CBA/J and C57BL/6) mice, and that 327 genes discriminated between early and late infection stages, between mouse strains, and between CM-R and CM-S mice. We further identified 104, 56, 84 genes with significant differential expression between CM-R and CM-S mice on days 2, 5, and 7 respectively. The analysis of their functional annotation suggests that genes involved in metabolic energy pathways, the inflammatory response, and the neuroprotection/neurotoxicity balance play a major role in cerebral malaria pathogenesis. In particular, we evidenced the down-regulation of genes involved in oxidative phosphorylation and the Reln pathway, and the up-regulation of genes involved in the NF-kB signalling pathway in CM-S mice. In addition, our data suggest that cerebral malaria and Alzheimers disease may share some common mechanisms of pathogenesis, as illustrated by the accumulation of beta-amyloid proteins in brains of CM-S mice, but not of CM-R mice. Our results indicate that microarray analyses can provide new insights into the key events that govern malaria pathogenesis.
Project description:We have used cDNA microarrays to compare gene expression profiles in brains from normal mice to those infected with the Anka strain of Plasmodium berghei, a model of cerebral malaria. For each of three brains in each group, we computed ratios of all quantifiable genes with a composite reference sample and then computed ratios of gene expression in infected brains with untreated controls. Of the almost 12,000 unigenes adequateluy quantified in all arrays, about 3% were significantly downregulated (p<0.05, >50% fold change) and about 7% were upregulated. Upon inspection of the lists of regulated genes, we identified a high number encoding proteins of importance to normal brain function or associated with neuropathology. These results emphasize the important impact of malarial infection on gene expression in brain and provide tentative target biomarkers that might provide novel therapeutic targets for neurological sequelae of disease. We have used a previously published protocol (Iacobas et al., Physiol Genomics 2005) and a composite reference RNA sample (R) prepared in sufficient quantity for the entire experiment from ten adult mouse tissues (aorta, brain, heart, kidney, liver, lung, ovary/testicles, spleen, and stomach - equal amounts from males and females). This combination of source tissues provided a high diversity of genes expressed in the midrange of the detection system for the AECOM mouse cDNA microarrays. Briefly, 60μg total RNA, extracted in Trizol® (Invitrogen, Carlsbad, CA) from brains of three infected (I) and three control (C) mice, purified with RNeasy® mini kit (Qiagen, Valencia, CA), were reverse transcribed into cDNA incorporating fluorescent Cy3-dUTP. The composite reference was reverse transcribed to incorporate Cy5-dUTP. Each of the six Cy3-labeled brain extracts was co-hybridized overnight at 50°C against the Cy5-labeled reference with AECOM 32k Mouse oligonucleotide arrays, MO3 printing series (platform described in http://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GPL5371). After hybridization, the slides were washed at room temperature, using solutions containing 0.1% sodium dodecyl sulfate (SDS) and 1% SSC (3M NaCl + 0.3M sodium citrate) to remove the non-hybridized cDNAs.
Project description:Gene expression patterns were investigated in well-defined genetically cerebral malaria-resistant (CM-R) and cerebral malaria-susceptible (CM-S) mouse strains. cDNA microarrays were used to search for differentially expressed genes in mouse brain. Four mouse strains, known to differ in susceptibility to cerebral malaria upon Plasmodium berghei ANKA infection, were compared: BALB/c and DBA/2 mice are CM-R, while C57BL/6 and CBA/J mice are CM-S.
Project description:Cerebral malaria (CM) lethality is attributable to brain edema induction but the cellular mechanisms involving brain microvascular endothelium in CM pathogenesis are unexplored. Activation of the STING-INFb-CXCL10 axis in brain endothelial cells (BECs) is a prominent component of the innate immune response in cerebral malaria (CM) development in mouse models. Using a T cell-reporter system, we show that Type 1 IFN signaling in BECs exposed to Plasmodium berghei-infected erythrocytes (PbA-IE), functionally enhances MHC Class-I antigen presentation through gamma-interferon independent immunoproteasome activation and impacted the proteome functionally related to vesicle trafficking, protein processing, and folding and antigen presentation. In vitro assays show that Type 1 IFN signaling and immunoproteasome activation are also involved in the dysfunction of the endothelial barrier through disturbing gene expression in the Wnt/ß-catenin signaling pathway. We demonstrate that IE exposure induces a substantial increase in BECs glucose uptake while glycolysis blockade abrogates INFb secretion impairing immunoproteasome activation, antigen presentation, and Wnt/ ß-catenin signaling. Metabolome analysis show that energy demand and production are markedly increased in BECs exposed to IE as revealed by enriched content in glucose and fatty acid catabolites. In accordance, glycolysis blockade in vivo delayed the clinical onset of CM in mice. Our results unveiled that Type 1 IFN signaling and subsequent immunoproteasome activation in BECs contribute to enhanced antigen presentation and the impairment of the endothelial barrier function. We also show that Type 1 IFN signaling and its downstream effects are licensed by dramatic increase in glucose uptake with an impact on energy metabolism pathways. This work raises the hypothesis that Type 1 IFN- immunoproteasome induction response in BECs contributes to CM pathology and fatality (1) by increasing antigen presentation to cytotoxic CD8+ T cells, which is a determinant of brain cytotoxic edema and (2) by promoting endothelial barrier dysfunction, that likely favors brain vasogenic edema.
Project description:We found that oral activated charcoal (oAC) provided significant protection against P. berghei ANKA-induced ECM, significantly increasing overall survival time compared to untreated mice. Protection from ECM by oAC was associated with a reduced numbers of splenic TNF+ CD4+ T cells and multifunctional IFNy+TNF+ CD4+ and CD8+ T cells. Furthermore, we identified a whole blood gene expression signature (68 genes) associated with protection from ECM. To evaluate whether oAC might affect current best available anti-malarial treatment, a group of female C57BL/6 mice infected with PbA received Activated Charcoal. At day 6 p.i., and prior to the first deaths of untreated PbA-infected mice, 5 untreated PbA-infected mice (Group 1) and 5 AC-treated PbA-infected mice (Group 2) were killed and fresh blood (300-500�l per mouse) was collected and processed into RNA. Blood was also taken from uninfected control mice (�baseline�- Group 3).
Project description:Infection of C57BL/6 mice with Plasmodium berghei ANKA (PbA) is a well-established experimental model of cerebral malaria (ECM). ECM is characterised by high levels of parasite sequestration and recruitment of pathogenic CD8+ T cells to the brain. The role of CD4+ T cells in this model has not yet been fully elucidated, although our laboratory has recently shown that CD4+ T cell depletion prior to infection results in significantly lower parasite burdens and protection from ECM. These data highlight a pathogenic role for CD4+ T cells in ECM. Our unpublished observations indicate that mice lacking the CD8+ T cell cytolytic effector molecule, Granzyme B, (GzmB), are resistant to ECM, showing markedly reduced parasite burdens. Late depletion of CD4+ T cells from PbA-infected GzmB-deficient mice results in enhanced parasite burdens, indicating that these cells may play an anti-parasitic role. In the present study, we have analysed splenic CD4+ T cell gene expression profiles in naïve C57BL/6 mice, and PbA-infected wild-type and GzmB-deficent mice to further our understanding of the CD4+ T cell response in ECM. Splenic CD4 T cells isolated by cell sorting from either uninfected C57BL/6 or PbA-infected C57BL/6 or B6.GzmB-/- mice at day 4 post-infection. Total RNA obtained from four mice per group.