RESUMO
The impact of cerebral malaria on the transcriptional profiles of cerebral tissues is difficult to study using noninvasive approaches. We isolated plasma extracellular vesicles (EVs) from patients with cerebral malaria and community controls and sequenced their mRNA content. Deconvolution analysis revealed that EVs from cerebral malaria are enriched in transcripts of brain origin. We ordered the patients with cerebral malaria based on their EV-transcriptional profiles from cross-sectionally collected samples and inferred disease trajectory while using healthy community controls as a starting point. We found that neuronal transcripts in plasma EVs decreased with disease trajectory, whereas transcripts from glial, endothelial, and immune cells increased. Disease trajectory correlated positively with severity indicators like death and was associated with increased VEGFA-VEGFR and glutamatergic signaling, as well as platelet and neutrophil activation. These data suggest that brain tissue responses in cerebral malaria can be studied noninvasively using EVs circulating in peripheral blood.
Assuntos
Encéfalo , Vesículas Extracelulares , Malária Cerebral , RNA Mensageiro , Humanos , Vesículas Extracelulares/metabolismo , Vesículas Extracelulares/genética , Malária Cerebral/parasitologia , Malária Cerebral/genética , Malária Cerebral/sangue , Malária Cerebral/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Encéfalo/metabolismo , Encéfalo/parasitologia , Feminino , Masculino , Adulto , Fator A de Crescimento do Endotélio Vascular/metabolismo , Fator A de Crescimento do Endotélio Vascular/genética , Fator A de Crescimento do Endotélio Vascular/sangue , Estudos de Casos e ControlesRESUMO
BACKGROUND: Transcriptomics has been used to evaluate immune responses during malaria in diverse cohorts worldwide. However, the high heterogeneity of cohorts and poor generalization of transcriptional signatures reported in each study limit their potential clinical applications. METHODS: We compiled 28 public data sets containing 1556 whole-blood or peripheral blood mononuclear cell transcriptome samples. We estimated effect sizes with Hedge's g value and the DerSimonian-Laird random-effects model for meta-analyses of uncomplicated malaria. Random forest models identified gene signatures that discriminate malaria from bacterial infections or malaria severity. Parasitological, hematological, immunological, and metabolomics data were used for validation. RESULTS: We identified 3 gene signatures: the uncomplicated Malaria Meta-Signature, which discriminates Plasmodium falciparum malaria from uninfected controls; the Malaria or Bacteria Signature, which distinguishes malaria from sepsis and enteric fever; and the cerebral Malaria Meta-Signature, which characterizes individuals with cerebral malaria. These signatures correlate with clinical hallmark features of malaria. Blood transcription modules indicate immune regulation by glucocorticoids, whereas cell development and adhesion are associated with cerebral malaria. CONCLUSIONS: Transcriptional meta-signatures reflecting immune cell responses provide potential biomarkers for translational innovation and suggest critical roles for metabolic regulators of inflammation during malaria.
Assuntos
Biomarcadores , Malária Falciparum , Plasmodium falciparum , Malária Falciparum/diagnóstico , Malária Falciparum/parasitologia , Humanos , Biomarcadores/sangue , Plasmodium falciparum/genética , Transcriptoma , Perfilação da Expressão Gênica , Malária Cerebral/diagnóstico , Malária Cerebral/genética , Malária Cerebral/sangue , Leucócitos Mononucleares/metabolismo , Leucócitos Mononucleares/imunologiaRESUMO
BACKGROUND: Cerebral malaria (CM) is a manifestation of malaria caused by plasmodium infection. It has a high mortality rate and severe neurological sequelae, existing a significant research gap and requiring further study at the molecular level. METHODS: We downloaded the GSE117613 dataset from the Gene Expression Omnibus (GEO) database to determine the differentially expressed genes (DEGs) between the CM group and the control group. Weighted gene coexpression network analysis (WGCNA) was applied to select the module and hub genes most relevant to CM. The common genes of the key module and DEGs were selected to perform further analysis. The least absolute shrinkage and selection operator (LASSO) logistic regression and support vector machine recursive feature elimination (SVM-RFE) were applied to screen and verify the diagnostic markers of CM. Eventually, the hub genes were validated in the external dataset. Gene set enrichment analysis (GSEA) was applied to investigate the possible roles of the hub genes. RESULTS: The GO and KEGG results showed that DEGs were enriched in some neutrophil-mediated pathways and associated with some lumen structures. Combining LASSO and the SVM-RFE algorithms, LEF1 and IRAK3 were identified as potential hub genes in CM. Through the GSEA enrichment results, we found that LEF1 and IRAK3 participated in maintaining the integrity of the blood-brain barrier (BBB), which contributed to improving the prognosis of CM. CONCLUSIONS: This study may help illustrate the pathophysiology of CM at the molecular level. LEF1 and IRAK3 can be used as diagnostic biomarkers, providing new insight into the diagnosis and prognosis prediction in pediatric CM.
Assuntos
Malária Cerebral , Criança , Humanos , Malária Cerebral/diagnóstico , Malária Cerebral/genética , África , Algoritmos , Aprendizado de Máquina , BiomarcadoresRESUMO
Complement Receptor Type 1 (CR1) is a malaria-associated gene that encodes a transmembrane receptor of erythrocytes and is crucial for malaria parasite invasion. The expression of CR1 contributes to the rosetting of erythrocytes in the brain bloodstream, causing cerebral malaria, the most severe form of the disease. Here, we study the history of adaptation against malaria by analyzing selection signals in the CR1 gene. We used whole-genome sequencing datasets of 907 healthy individuals from malaria-endemic and non-endemic populations. We detected robust positive selection in populations from the hyperendemic regions of East India and Papua New Guinea. Importantly, we identified a new adaptive variant, rs12034598, which is associated with a slower rate of erythrocyte sedimentation and is linked with a variant associated with low levels of CR1 expression. The combination of the variants likely drives natural selection. In addition, we identified a variant rs3886100 under positive selection in West Africans, which is also related to a low level of CR1 expression in the brain. Our study shows the fine-resolution history of positive selection in the CR1 gene and suggests a population-specific history of CR1 adaptation to malaria. Notably, our novel approach using population genomic analyses allows the identification of protective variants that reduce the risk of malaria infection without the need for patient samples or malaria individual medical records. Our findings contribute to understanding of human adaptation against cerebral malaria.
Assuntos
Malária Cerebral , Receptores de Complemento 3b , Humanos , Eritrócitos , Malária Cerebral/genética , Malária Cerebral/metabolismo , Papua Nova Guiné , Receptores de Complemento 3b/genética , Seleção Genética , Genética Populacional , ÍndiaRESUMO
BACKGROUND: Inducible expression of heme oxygenase-1 (encoded by the gene HMOX1) may determine protection from heme released during malaria infections. A variable length, short tandem GT(n) repeat (STR) in HMOX1 that may influence gene expression has been associated with outcomes of human malaria in some studies. In this study, an analysis of the association between variation at the STR in HMOX1 on severe malaria and severe malaria subtypes is presented in a large, prospectively collected dataset (MalariaGEN). METHODS: The HMOX1 STR was imputed using a recently developed reference haplotype panel designed for STRs. The STR was classified by total length and split into three alleles based on an observed trimodal distribution of repeat lengths. Logistic regression was used to assess the association between this repeat on cases of severe malaria and severe malaria subtypes (cerebral malaria and severe malarial anaemia). Individual analyses were performed for each MalariaGEN collection site and combined for meta-analysis. One site (Kenya), had detailed clinical metadata, allowing the assessment of the effect of the STR on clinical variables (e.g. parasite count, platelet count) and regression analyses were performed to investigate whether the STR interacted with any clinical variables. RESULTS: Data from 17,960 participants across 11 collection sites were analysed. In logistic regression, there was no strong evidence of association between STR length and severe malaria (Odds Ratio, OR: 0.96, 95% confidence intervals 0.91-1.02 per ten GT(n) repeats), although there did appear to be an association at some sites (e.g., Kenya, OR 0.90, 95% CI 0.82-0.99). There was no evidence of an interaction with any clinical variables. CONCLUSIONS: Meta-analysis suggested that increasing HMOX1 STR length is unlikely to be reliably associated with severe malaria. It cannot be ruled out that repeat length may alter risk in specific populations, although whether this is due to chance variation, or true variation due to underlying biology (e.g., gene vs environment interaction) remains unanswered.
Assuntos
Heme Oxigenase-1 , Malária Cerebral , Humanos , Heme Oxigenase-1/genética , Heme Oxigenase-1/metabolismo , Predisposição Genética para Doença , Polimorfismo Genético , Alelos , Malária Cerebral/genéticaRESUMO
BACKGROUND: cerebral malaria (CM) is an important complication of malaria with a high mortality rate. Artesunate is recommended as the first-line artemisinin compound treatment for severe malaria. Due to the difficulty of obtaining brain tissue samples clinically, the use of animals to research host responses to CM parasite infections is necessary. Rodent malaria models allow for detailed time series studies of host responses in multiple organs. To date, studies on the transcriptome of severe malaria are only limited to the parasites in the peripheral blood of patients, and there is little data on the transcriptional changes in brain tissue in mice with CM treated with artesunate. METHOD AND RESULT: in this study, fresh tissue samples (three biological replicates per mouse) from the same area of the brain in each animal were collected from the uninfected, Plasmodium berghei ANKA-infected and artesunate-treated C57BL/6 mice, and then transcriptome research was performed by the RNA-seq technique. Differentially expressed genes (DEGs) included Il-21, Tnf, Il-6, Il-1ß, Il-10, Ifng, and Icam-1. Among which, Il-6, Il-10, Tnf-α and Il-1ß were further verified and validated via qRT-PCR and ELISA. This revealed that Il-1ß (p < 0.0001), Il-10 (p < 0.05) and Tnf-α (p < 0.05) were significantly up-regulated in the Pb ANKA-infected versus uninfected group, while Il-1ß (p < 0.0001) and Tnf-α (p < 0.05) were significantly down-regulated after artesunate treatment. All DEGs were closely related to the top 3 artesunate treatment pathways, including the JAK-STAT signaling pathway, apoptosis, and Toll-like receptor signaling pathway. CONCLUSION: the mechanism of improving the prognosis of cerebral malaria by artesunate may not only involve the killing of plasmodium but also the inhibition of a cytokine storm in the host. This study provides new insights into the molecular mechanism by which artesunate improves the prognosis of cerebral malaria.
Assuntos
Antimaláricos , Artemisininas , Malária Cerebral , Animais , Anti-Inflamatórios/uso terapêutico , Antimaláricos/farmacologia , Antimaláricos/uso terapêutico , Artemisininas/farmacologia , Artemisininas/uso terapêutico , Artesunato/farmacologia , Artesunato/uso terapêutico , Modelos Animais de Doenças , Perfilação da Expressão Gênica , Molécula 1 de Adesão Intercelular/uso terapêutico , Interleucina-10/uso terapêutico , Interleucina-6/uso terapêutico , Chumbo/uso terapêutico , Malária Cerebral/tratamento farmacológico , Malária Cerebral/genética , Malária Cerebral/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , RNA-Seq , Receptores Toll-Like/uso terapêutico , Fator de Necrose Tumoral alfa/uso terapêuticoRESUMO
Plasmodium falciparum, the deadliest form of human malaria, remains one of the major threats to human health in endemic regions. Its virulence is attributed to its ability to modify infected red blood cells (iRBC) to adhere to endothelial receptors by placing variable antigens known as PfEMP1 on the iRBC surface. PfEMP1 expression determines the cytoadhesive properties of the iRBCs and is implicated in severe malaria. To evade antibody-mediated responses, the parasite undergoes continuous switches of expression between different PfEMP1 variants. Recently, it became clear that in addition to antibody-mediated responses, PfEMP1 triggers innate immune responses; however, the role of neutrophils, the most abundant white blood cells in the human circulation, in malaria remains elusive. Here, we show that neutrophils recognize and kill blood-stage P. falciparum isolates. We identify neutrophil ICAM-1 and specific PfEMP1 implicated in cerebral malaria as the key molecules involved in this killing. Our data provide mechanistic insight into the interactions between neutrophils and iRBCs and demonstrate the important influence of PfEMP1 on the selective innate response to cerebral malaria.
Assuntos
Malária Cerebral , Malária Falciparum , Plasmodium falciparum , Eritrócitos/parasitologia , Humanos , Malária Cerebral/genética , Malária Cerebral/metabolismo , Malária Falciparum/genética , Neutrófilos/metabolismo , Plasmodium falciparum/genética , Plasmodium falciparum/fisiologia , Proteínas de Protozoários/genética , Proteínas de Protozoários/metabolismoRESUMO
Cerebral malaria (CM) may cause death or long-term neurological damage in children, and several host genetic risk factors have been reported. Malaria-specific immunoglobulin (Ig) G3 antibodies are crucial to human immune response against malaria. The hinge region of IgG3 exhibits length polymorphism (with long [L], medium [M], and short [S] alleles), which may influence its functionality. We studied IgG3 hinge region length polymorphisms in 136 Ghanaian children with malaria. Using logistic regression models, we found that children with the recessive MM allotype encoding medium IgG3 hinge region length had an increased risk of CM (adjusted odds ratio, 6.67 [95% confidence interval,1.30-34.32]; P=.004) . This has implications for future epidemiological studies on CM.
Assuntos
Anticorpos Antiprotozoários , Imunoglobulina G , Malária Cerebral , Malária Falciparum , Anticorpos Antiprotozoários/genética , Criança , Gana/epidemiologia , Humanos , Imunoglobulina G/genética , Malária Cerebral/epidemiologia , Malária Cerebral/genética , Malária Falciparum/epidemiologia , Malária Falciparum/genética , Plasmodium falciparumRESUMO
Malaria is a major international public health problem that affects millions of patients worldwide especially in sub-Saharan Africa. Although many tests have been developed to diagnose malaria infections, we still lack reliable diagnostic biomarkers for the identification of disease severity, especially in endemic areas where the diagnosis of cerebral malaria is very difficult and requires the exclusion of all other possible causes. Previous host and pathogen transcriptomic studies have not yielded homogenous results that can be harnessed into a reliable diagnostic tool. Here we utilized a multi-cohort analysis approach using machine-learning algorithms to identify blood gene signatures that can distinguish severe and cerebral malaria from moderate and non-cerebral cases. Using a Regularized Random Forest model, we identified 28-gene and 32-gene signatures that can reliably distinguish severe and cerebral malaria, respectively. We tested the specificity of both signatures against other common infectious diseases to ensure the signatures reliability and suitability as diagnostic markers. The severe and cerebral malaria gene-signatures were further integrated through k-top scoring pairs classifiers into ten and nine gene pairs that could distinguish severe and cerebral malaria, respectively. These signatures have various implications that can be utilized as blood diagnostic tools for malaria severity in endemic countries.
Assuntos
Malária Cerebral , Malária Falciparum , Estudos de Coortes , Humanos , Malária Cerebral/diagnóstico , Malária Cerebral/genética , Reprodutibilidade dos Testes , Índice de Gravidade de DoençaRESUMO
BACKGROUND: Recent genome wide analysis studies have identified a strong association between single nucleotide variations within the human ATP2B4 gene and susceptibility to severe malaria. The ATP2B4 gene encodes the plasma membrane calcium ATPase 4 (PMCA4), which is responsible for controlling the physiological level of intracellular calcium in many cell types, including red blood cells (RBCs). It is, therefore, postulated that genetic differences in the activity or expression level of PMCA4 alters intracellular Ca2+ levels and affects RBC hydration, modulating the invasion and growth of the Plasmodium parasite within its target host cell. METHODS: In this study the course of three different Plasmodium spp. infections were examined in mice with systemic knockout of Pmca4 expression. RESULTS: Ablation of PMCA4 reduced the size of RBCs and their haemoglobin content but did not affect RBC maturation and reticulocyte count. Surprisingly, knockout of PMCA4 did not significantly alter peripheral parasite burdens or the dynamics of blood stage Plasmodium chabaudi infection or reticulocyte-restricted Plasmodium yoelii infection. Interestingly, although ablation of PMCA4 did not affect peripheral parasite levels during Plasmodium berghei infection, it did promote slight protection against experimental cerebral malaria, associated with a minor reduction in antigen-experienced T cell accumulation in the brain. CONCLUSIONS: The finding suggests that PMCA4 may play a minor role in the development of severe malarial complications, but that this appears independent of direct effects on parasite invasion, growth or survival within RBCs.
Assuntos
Resistência à Doença/genética , Malária/genética , ATPases Transportadoras de Cálcio da Membrana Plasmática/genética , Plasmodium/fisiologia , Animais , Membrana Celular , Malária/sangue , Malária/parasitologia , Malária Cerebral/genética , Malária Cerebral/parasitologia , Camundongos , Camundongos Knockout , ATPases Transportadoras de Cálcio da Membrana Plasmática/metabolismo , Plasmodium berghei/fisiologia , Plasmodium chabaudi/fisiologia , Plasmodium yoelii/fisiologiaAssuntos
Biomarcadores/sangue , Regulação da Expressão Gênica , Imageamento por Ressonância Magnética/métodos , Malária Cerebral/patologia , Malária Falciparum/patologia , MicroRNAs/genética , Plasmodium falciparum/fisiologia , Estudos de Casos e Controles , Humanos , Malária Cerebral/sangue , Malária Cerebral/genética , Malária Cerebral/parasitologia , Malária Falciparum/sangue , Malária Falciparum/genética , Malária Falciparum/parasitologia , MicroRNAs/sangue , Estudos RetrospectivosRESUMO
INTRODUCTION: A vaccine for malaria is urgently required but no vaccine has yet shown satisfactory protective efficacy especially for Plasmodium falciparum. P. falciparum infection can progress to cerebral malaria (CM), a neurological syndrome with exceedingly high mortality. Designing effective P. falciparum vaccines require more understanding of the protective immune response while the host immune response to CM and the mechanisms are still elusive. Here, we aim to identify host gene responses to CM and host gene networks associated with CM pathogenesis. METHODS: An innovative genomic analysis strategy, the weighted gene coexpression network analysis (WGCNA) combined with differential gene expression analysis, was used in this study. Data for analysis contain 93 whole blood samples, derived from two previous public transcriptome datasets. RESULTS: This approach led to the identification of numerous differentially expressed human transcripts and dozens of coexpression gene modules. We further identified nine key genes, including MBP, SAMSN1, PSMF1, SLC39A8, EIF3B, SMPDL3A, FABP5, SPSB3, and SHARPIN, of which the last four genes were first identified to be related to CM in the present study. CONCLUSION: The results provided a comprehensive characterization of host gene expression profiles in CM and offered some new insight into malaria vaccine design. These identified key genes could be potential targets or immune modulators for novel therapeutic interventions of CM.
Assuntos
Malária Cerebral , Malária Falciparum , Proteínas Adaptadoras de Transporte Vesicular , Proteínas de Ligação a Ácido Graxo , Genômica , Humanos , Imunidade , Malária Cerebral/genética , Malária Falciparum/genética , Plasmodium falciparum/genéticaRESUMO
Persistent high levels of proinflammatory and Th1 responses contribute to cerebral malaria (CM). Suppression of inflammatory responses and promotion of Th2 responses prevent pathogenesis. IL-4 commonly promotes Th2 responses and inhibits inflammatory and Th1 responses. Therefore, IL-4 is widely considered as a beneficial cytokine via its Th2-promoting role that is predicted to provide protection against severe malaria by inhibiting inflammatory responses. However, IL-4 may also induce inflammatory responses, as the result of IL-4 action depends on the timing and levels of its production and the tissue environment in which it is produced. Recently, we showed that dendritic cells (DCs) produce IL-4 early during malaria infection in response to a parasite protein and that this IL-4 response may contribute to severe malaria. However, the mechanism by which IL-4 produced by DCs contributing to lethal malaria is unknown. Using Plasmodium berghei ANKA-infected C57BL/6 mice, a CM model, we show here that mice lacking IL-4Rα only in CD8α+ DCs are protected against CM pathogenesis and survive, whereas WT mice develop CM and die. Compared with WT mice, mice lacking IL-4Rα in CD11c+ or CD8α+ DCs showed reduced inflammatory responses leading to decreased Th1 and cytotoxic CD8+ T cell responses, lower infiltration of CD8+ T cells to the brain, and negligible brain pathology. The novel results presented here reveal a paradoxical role of IL-4Rα signaling in CM pathogenesis that promotes CD8α+ DC-mediated inflammatory responses that generate damaging Th1 and cytotoxic CD8+ T cell responses.
Assuntos
Antígenos CD8/imunologia , Linfócitos T CD8-Positivos/imunologia , Células Dendríticas/imunologia , Malária Cerebral/imunologia , Plasmodium berghei/imunologia , Receptores de Superfície Celular/imunologia , Transdução de Sinais/imunologia , Células Th1/imunologia , Animais , Antígenos CD8/genética , Linfócitos T CD8-Positivos/patologia , Células Dendríticas/patologia , Interleucina-4/genética , Interleucina-4/imunologia , Malária Cerebral/genética , Malária Cerebral/patologia , Camundongos , Camundongos Knockout , Plasmodium berghei/genética , Receptores de Superfície Celular/genética , Transdução de Sinais/genética , Células Th1/patologia , Células Th2/imunologia , Células Th2/patologiaRESUMO
The Plasmodium falciparum erythrocyte-membrane-protein-1 (PF3D7_1150400/PF11_0521) contains both domain cassette DC13 and DBLß3 domain binding to EPCR and ICAM-1 receptors, respectively. This type of PfEMP1 proteins with dual binding specificity mediate specific interactions with brain micro-vessels endothelium leading to the development of cerebral malaria (CM). Using plasma collected from children at time of hospital admission and after 30 days, we study an acquisition of IgG response to PF3D7_1150400/PF11_0521 DC13 and DBLß3_D4 recombinant constructs, and five peptides located within these constructs, specifically in DBLα1.7_D2 and DBLß3_D4 domains. We found significant IgG responses against the entire DC13, PF11_0521_DBLß3_D4 domain, and peptides. The responses varied against different peptides and depended on the clinical status of children. The response was stronger at day 30, and mostly did not differ between CM and uncomplicated malaria (UM) groups. Specifically, the DBLß3 B3-34 peptide that contains essential residues involved in the interaction between PF11_0521 DBLß3_D4 domain and ICAM-1 receptor demonstrated significant increase in reactivity to IgG1 and IgG3 antibodies at convalescence. Further, IgG reactivity in CM group at time of admission against functionally active (ICAM-1-binding) PF11_0521 DBLß3_D4 domain was associated with protection against severe anemia. These results support development of vaccine based on the PF3D7_1150400/PF11_0521 structures to prevent CM.
Assuntos
Imunoglobulina G/sangue , Malária Cerebral/imunologia , Malária Falciparum/imunologia , Peptídeos/imunologia , Proteínas de Protozoários/imunologia , Anemia/complicações , Anticorpos Antiprotozoários/sangue , Anticorpos Antiprotozoários/imunologia , Antígenos de Protozoários/sangue , Antígenos de Protozoários/imunologia , Encéfalo/imunologia , Encéfalo/metabolismo , Encéfalo/parasitologia , Encéfalo/patologia , Pré-Escolar , Receptor de Proteína C Endotelial/genética , Receptor de Proteína C Endotelial/imunologia , Endotélio Vascular/metabolismo , Endotélio Vascular/parasitologia , Eritrócitos/parasitologia , Feminino , Humanos , Imunoglobulina G/imunologia , Lactente , Molécula 1 de Adesão Intercelular/genética , Molécula 1 de Adesão Intercelular/imunologia , Malária Cerebral/sangue , Malária Cerebral/genética , Malária Cerebral/parasitologia , Malária Falciparum/sangue , Malária Falciparum/genética , Malária Falciparum/parasitologia , Masculino , Peptídeos/genética , Plasmodium falciparum/genética , Plasmodium falciparum/patogenicidade , Ligação Proteica/genética , Ligação Proteica/imunologia , Proteínas de Protozoários/genéticaRESUMO
Cerebral malaria (CM) is the most severe complication caused by Plasmodium falciparum infection. The pathophysiological changes caused by parasite virulence factors and the human immune response to parasites contribute to CM. To date, very few parasite virulence proteins have been found to participate in CM. Here, we employed comparative genomics analysis and identified parasite-infected erythrocyte specific protein 2 (PIESP2) to be a CM-related protein. We conducted further experimental investigations and found that PIESP2 is an immunogenic protein. PIESP2 expression begins at the early trophozoite stage and progressively increases with parasite development. Although PIESP2 proteins mainly reside within infected red blood cells (IRBCs), some of them are present on the IRBC surface at the pigmented stage. Moreover, blockage of PIESP2 by antiserum apparently inhibited the adhesion of IRBCs to brain microvascular endothelial cells (BMECs). Western blot analysis detected the binding of PIESP2 to BMECs. Transcriptional analysis revealed that the binding of PIESP2 to BMECs can increase the expression of genes involved in the inflammatory response but decrease the expression of genes related to the anchoring junction. Overall, PIESP2 might be associated with CM by mediating the sequestration of IRBCs, inducing the inflammation response, and impairing the integrity of blood-brain barrier.
Assuntos
Malária Cerebral/genética , Malária Falciparum/genética , Plasmodium falciparum/genética , Proteínas de Protozoários/genética , Fatores de Virulência/genética , Humanos , Malária Cerebral/metabolismo , Malária Falciparum/metabolismo , Plasmodium falciparum/metabolismo , Plasmodium falciparum/patogenicidade , Proteínas de Protozoários/metabolismo , Fatores de Virulência/metabolismoRESUMO
Earlier studies indicate that either the canonical or non-canonical pathways of inflammasome activation have a limited role on malaria pathogenesis. Here, we report that caspase-8 is a central mediator of systemic inflammation, septic shock in the Plasmodium chabaudi-infected mice and the P. berghei-induced experimental cerebral malaria (ECM). Importantly, our results indicate that the combined deficiencies of caspases-8/1/11 or caspase-8/gasdermin-D (GSDM-D) renders mice impaired to produce both TNFα and IL-1ß and highly resistant to lethality in these models, disclosing a complementary, but independent role of caspase-8 and caspases-1/11/GSDM-D in the pathogenesis of malaria. Further, we find that monocytes from malaria patients express active caspases-1, -4 and -8 suggesting that these inflammatory caspases may also play a role in the pathogenesis of human disease.
Assuntos
Caspase 8/metabolismo , Inflamação/patologia , Malária Cerebral/enzimologia , Animais , Encéfalo/patologia , Caspase 1/metabolismo , Células Dendríticas/metabolismo , Ativação Enzimática , Matriz Extracelular/metabolismo , Regulação da Expressão Gênica , Humanos , Interferon gama/metabolismo , Interleucina-1beta/metabolismo , Lipopolissacarídeos , Malária Cerebral/genética , Camundongos Endogâmicos C57BL , Monócitos/metabolismo , Plasmodium chabaudi/fisiologia , Baço/metabolismo , Receptores Toll-Like/metabolismoRESUMO
BACKGROUND: Cerebral malaria (CM), a reversible encephalopathy affecting young children, is a medical emergency requiring rapid clinical assessment and treatment. However, understanding of the genes/proteins and the biological pathways involved in the disease outcome is still limited. METHODS: We have performed a whole transcriptomic analysis of blood samples from Malian children with CM or uncomplicated malaria (UM). Hierarchical clustering and pathway, network, and upstream regulator analyses were performed to explore differentially expressed genes (DEGs). We validated gene expression for 8 genes using real-time quantitative PCR (RT-qPCR). Plasma levels were measured for IP-10/CXCL10 and IL-18. RESULTS: A blood RNA signature including 538 DEGs (â£FC | ≥2.0, adjusted P value ≤ 0.01) allowed to discriminate between CM and UM. Ingenuity Pathway Analysis (IPA) and Kyoto Encyclopedia of Genes and Genomes (KEGG) revealed novel genes and biological pathways related to immune/inflammatory responses, erythrocyte alteration, and neurodegenerative disorders. Gene expressions of CXCL10, IL12RB2, IL18BP, IL2RA, AXIN2, and NET were significantly lower in CM whereas ARG1 and SLC6A9 were higher in CM compared to UM. Plasma protein levels of IP-10/CXCL10 were significantly lower in CM than in UM while levels of IL-18 were higher. Interestingly, among children with CM, those who died from a complication of malaria tended to have higher concentrations of IP-10/CXCL10 and IFN-γ than those who recovered. CONCLUSIONS: This study identified some new factors and mechanisms that play crucial roles in CM and characterized their respective biological pathways as well as some upstream regulators.
Assuntos
Encéfalo/metabolismo , Eritrócitos/metabolismo , Inflamação/sangue , Malária Cerebral/genética , Malária Cerebral/metabolismo , Transcriptoma/genética , Quimiocina CXCL10/sangue , Biologia Computacional/métodos , Humanos , Interleucina-18/sangue , Análise de Sequência com Séries de Oligonucleotídeos , Reação em Cadeia da Polimerase Via Transcriptase ReversaRESUMO
Heterogeneity and high plasticity are common features of cells from the mononuclear phagocyte system: monocytes (MOs), macrophages, and dendritic cells (DCs). Upon activation by microbial agents, MO can differentiate into MO-derived DCs (MODCs). In previous work, we have shown that during acute infection with Plasmodium berghei ANKA (PbA), MODCs become, transiently, the main CD11b+ myeloid population in the spleen (SP) and once recruited to the brain play an important role in the development of experimental cerebral malaria (ECM). Here, we isolated 4 cell populations: bone marrow (BM) MOs (BM-MOs) and SP-MOs from uninfected mice; BM inflammatory MOs (BM-iMOs) and SP-MODCs from PbA-infected mice and used a system biology approach to a holistic transcriptomic comparison and provide an interactome analysis by integrating differentially expressed miRNAs (DEMs) and their differentially expressed gene targets (DEGs) data. The Jaccard index (JI) was used for gauging the similarity and diversity among these cell populations. Whereas BM-MOs, BM-iMOs, and SP-MOs presented high similarity of DEGs, SP-MODCs distinguished by showing a greater number of DEGs. Moreover, functional analysis identified an enrichment in canonical pathways, such as DC maturation, neuroinflammation, and IFN signaling. Upstream regulator analysis identified IFNγ as the potential upstream molecule that can explain the observed DEMs-Target DEGs intersections in SP-MODCs. Finally, directed target analysis and in vivo/ex vivo assays indicate that SP-MODCs differentiate in the SP and IFNγ is a main driver of this process.
Assuntos
Células Dendríticas/imunologia , Regulação da Expressão Gênica/imunologia , Malária Cerebral/imunologia , MicroRNAs/imunologia , Monócitos/imunologia , Plasmodium berghei/imunologia , RNA Mensageiro/imunologia , Animais , Células Dendríticas/patologia , Malária Cerebral/genética , Malária Cerebral/patologia , Camundongos , Camundongos Knockout , MicroRNAs/genética , Monócitos/patologia , RNA Mensageiro/genética , Transcriptoma/imunologiaRESUMO
Disruption of blood-brain barrier (BBB) function is a key feature of cerebral malaria. Increased barrier permeability occurs due to disassembly of tight and adherens junctions between endothelial cells, yet the mechanisms governing junction disassembly and vascular permeability during cerebral malaria remain poorly characterized. We found that EphA2 is a principal receptor tyrosine kinase mediating BBB breakdown during Plasmodium infection. Upregulated on brain microvascular endothelial cells in response to inflammatory cytokines, EphA2 is required for the loss of junction proteins on mouse and human brain microvascular endothelial cells. Furthermore, EphA2 is necessary for CD8+ T cell brain infiltration and subsequent BBB breakdown in a mouse model of cerebral malaria. Blocking EphA2 protects against BBB breakdown highlighting EphA2 as a potential therapeutic target for cerebral malaria.
Assuntos
Barreira Hematoencefálica/parasitologia , Malária Cerebral/parasitologia , Receptor EphA2/metabolismo , Adolescente , Animais , Barreira Hematoencefálica/metabolismo , Criança , Pré-Escolar , Estudos Transversais , Feminino , Humanos , Lactente , Malária Cerebral/genética , Malária Cerebral/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Plasmodium falciparum/fisiologia , Receptor EphA2/genéticaRESUMO
We used a genome-wide screen in N-ethyl-N-nitrosourea (ENU)-mutagenized mice to identify genes in which recessive loss-of-function mutations protect against pathological neuroinflammation. We identified an R367Q mutation in the ZBTB7B (ThPOK) protein in which homozygosity causes protection against experimental cerebral malaria (ECM) caused by infection with Plasmodium berghei ANKA. Zbtb7bR367Q homozygous mice show a defect in the lymphoid compartment expressed as severe reduction in the number of single-positive CD4 T cells in the thymus and in the periphery, reduced brain infiltration of proinflammatory leukocytes in P. berghei ANKA-infected mice, and reduced production of proinflammatory cytokines by primary T cells ex vivo and in vivo Dampening of proinflammatory immune responses in Zbtb7bR367Q mice is concomitant to increased susceptibility to infection with avirulent (Mycobacterium bovis BCG) and virulent (Mycobacterium tuberculosis H37Rv) mycobacteria. The R367Q mutation maps to the first DNA-binding zinc finger domain of ThPOK and causes loss of base contact by R367 in the major groove of the DNA, which is predicted to impair DNA binding. Global immunoprecipitation of ThPOK-containing chromatin complexes coupled to DNA sequencing (ChIP-seq) identified transcriptional networks and candidate genes likely to play key roles in CD4+ CD8+ T cell development and in the expression of lineage-specific functions of these cells. This study highlights ThPOK as a global regulator of immune function in which alterations may affect normal responses to infectious and inflammatory stimuli.