RESUMO
BACKGROUND: Cerebral malaria (CM) is a severe immunovasculopathy caused for Plasmodium falciparum infection, which is characterised by the sequestration of parasitised red blood cells (pRBCs) in brain microvessels. Previous studies have shown that some terpenes, such as perillyl alcohol (POH), exhibit a marked efficacy in preventing cerebrovascular inflammation, breakdown of the brain-blood barrier (BBB) and brain leucocyte accumulation in experimental CM models. OBJECTIVE: To analyse the effects of POH on the endothelium using human brain endothelial cell (HBEC) monolayers co-cultured with pRBCs. METHODOLOGY: The loss of tight junction proteins (TJPs) and features of endothelial activation, such as ICAM-1 and VCAM-1 expression were evaluated by quantitative immunofluorescence. Microvesicle (MV) release by HBEC upon stimulation by P. falciparum was evaluated by flow cytometry. Finally, the capacity of POH to revert P. falciparum-induced HBEC monolayer permeability was examined by monitoring trans-endothelial electrical resistance (TEER). FINDINGS: POH significantly prevented pRBCs-induced endothelial adhesion molecule (ICAM-1, VCAM-1) upregulation and MV release by HBEC, improved their trans-endothelial resistance, and restored their distribution of TJPs such as VE-cadherin, Occludin, and JAM-A. CONCLUSIONS: POH is a potent monoterpene that is efficient in preventing P. falciparum-pRBCs-induced changes in HBEC, namely their activation, increased permeability and alterations of integrity, all parameters of relevance to CM pathogenesis.
Assuntos
Malária Cerebral , Malária Falciparum , Humanos , Plasmodium falciparum , Molécula 1 de Adesão Intercelular/metabolismo , Células Endoteliais , Molécula 1 de Adesão de Célula Vascular/metabolismo , Encéfalo/metabolismo , Encéfalo/patologia , Malária Cerebral/metabolismo , Malária Cerebral/patologia , Monoterpenos/metabolismo , Barreira Hematoencefálica/metabolismo , Barreira Hematoencefálica/patologia , Endotélio Vascular , PermeabilidadeRESUMO
This review will provide a better understanding of a set of signs known as malarial retinopathy. The discovery of this retinopathy in association with cerebral malaria is important because it best distinguishes patients with true cerebral malaria from those with coma due to other causes and incidental Plasmodium falciparum parasitemia. Identifying a comatose patient with malarial retinopathy increases the likelihood of an accurate severe or cerebral malaria diagnosis. As the World Health Organization does not specify that malarial retinopathy is one of the factors included in determining a cerebral malaria diagnosis, there are significant false-positive diagnoses of cerebral malaria. Once a cerebral malaria diagnosis is assigned, other possibilities and treatments are often excluded making an incorrect diagnosis of cerebral malaria potentially fatal. However, Plasmodium falciparum may also contribute to coma in some children with retinopathy-negative cerebral malaria, as this group is still not clinically well characterized, so all children with the WHO definition of cerebral malaria should be treated for severe malaria. Nevertheless, by raising awareness about malarial retinopathy, there could be a greater potential to accurately diagnose cerebral malaria and thus achieve more positive patient outcomes in the future. This literary review aims to raise awareness of the retinopathy by defining what it is to non-experts, explaining its pathology, clarifying the techniques needed to accurately diagnose malarial retinopathy, as well as the barriers that prevent clinicians from providing a proper diagnosis in malaria-endemic regions; and finally, discuss future directions to continue the study of malarial retinopathy.
Assuntos
Malária Cerebral , Malária Falciparum , Doenças Retinianas , Criança , Humanos , Malária Cerebral/diagnóstico , Malária Cerebral/patologia , Coma/diagnóstico , Doenças Retinianas/diagnóstico , Doenças Retinianas/patologia , Plasmodium falciparum , Malária Falciparum/diagnósticoRESUMO
Cerebral malaria (CM) is a neurological complication derived from the Plasmodium falciparum infection in humans. The mechanisms involved in the disease progression are still not fully understood, but both the sequestration of infected red blood cells (iRBC) and leukocytes and an exacerbated host inflammatory immune response are significant factors. In this study, we investigated the effect of Monocyte Locomotion Inhibitory Factor (MLIF), an anti-inflammatory peptide, in a well-characterized murine model of CM. Our data showed that the administration of MLIF increased the survival and avoided the neurological signs of CM in Plasmodium berghei ANKA (PbA) infected C57BL/6 mice. MLIF administration down-regulated systemic inflammatory mediators such as IFN-γ, TNF-α, IL-6, CXCL2, and CCL2, as well as the in situ expression of TNF-α in the brain. In the same way, MLIF reduced the expression of CD31, CD36, CD54, and CD106 in the cerebral endothelium of infected animals and prevented the sequestration of iRBC and leucocytes in the brain microvasculature. Furthermore, MLIF inhibited the activation of astrocytes and microglia and preserved the integrity of the blood-brain barrier (BBB). In conclusion, our results demonstrated that the administration of MLIF increased survival and conferred neuroprotection by decreasing neuroinflammation in murine CM.
Assuntos
Anti-Inflamatórios/administração & dosagem , Malária Cerebral/prevenção & controle , Fármacos Neuroprotetores/administração & dosagem , Oligopeptídeos/administração & dosagem , Animais , Astrócitos/efeitos dos fármacos , Astrócitos/imunologia , Encéfalo/efeitos dos fármacos , Encéfalo/imunologia , Encéfalo/patologia , Modelos Animais de Doenças , Regulação para Baixo/efeitos dos fármacos , Regulação para Baixo/imunologia , Feminino , Humanos , Mediadores da Inflamação/antagonistas & inibidores , Mediadores da Inflamação/metabolismo , Malária Cerebral/imunologia , Malária Cerebral/parasitologia , Malária Cerebral/patologia , Camundongos , Microglia/efeitos dos fármacos , Microglia/imunologia , Plasmodium berghei/imunologiaRESUMO
Cerebral malaria pathogenesis involves vascular dysfunction with low nitric oxide (NO) bioavailability, vasoconstriction and impaired vasodilation, leading to ischemia, tissue hypoxia and ultimately death. Cerebral blood flow (CBF) involves NO and other pathways, including arachidonic acid (AA)-derived metabolites. Here we show that mice with experimental cerebral malaria (ECM) by P. berghei ANKA showed marked decreases in CBF (as assessed by laser speckle contrast imaging - LSCI) and that administration of L-arginine supplementation (50 mg/kg) and/or of the thromboxane synthase inhibitor Ozagrel (100 mg/kg) induced immediate increases in CBF. L-arginine in combination with artesunate (32 mg/kg) induced immediate reversal of brain ischemia in the short-term (1 hour), but the effect subsided after 3 and 6 hours. Neither L-arginine nor Ozagrel reversed blood brain barrier breakdown. Mice with ECM showed brain levels of selected AA-derived metabolites with a vasoconstrictor profile, with increased levels of 8-isoprostanes, 20-HETE and 14,15-DHET, whereas mice infected with a non-ECM-inducing strain of P. berghei (NK65) showed a vasodilator profile, with normal levels of 20-HETE and 14,15-DHET and increased levels of PGE2. L-arginine is capable of partially reversing cerebral ischemia and AA metabolites may play a role in the cerebrovascular dysfunction in ECM.
Assuntos
Arginina/farmacologia , Circulação Cerebrovascular/efeitos dos fármacos , Malária Cerebral/patologia , Animais , Arginina/metabolismo , Barreira Hematoencefálica/efeitos dos fármacos , Encéfalo/patologia , Suplementos Nutricionais , Feminino , Malária Cerebral/metabolismo , Metacrilatos/metabolismo , Metacrilatos/farmacologia , Camundongos , Camundongos Endogâmicos C57BL , Plasmodium berghei/efeitos dos fármacos , Tromboxano-A Sintase/antagonistas & inibidores , Tromboxano-A Sintase/metabolismo , Tromboxanos/antagonistas & inibidores , Tromboxanos/metabolismo , Vasoconstrição/efeitos dos fármacosRESUMO
Increased resistance to the first-line treatment against P. falciparum malaria, artemisinin-based combination therapies, has been reported. Here, we tested the effect of crude ethanolic extract of the fungus Trichoderma stromaticum (Ext-Ts) on the growth of P. falciparum NF54 in infected human red blood cells (ihRBCs) and its anti-malarial and anti-inflammatory properties in a mouse model of experimental cerebral malaria. For this purpose, ihRBCs were treated with Ext-Ts and analysed for parasitaemia; C57BL/6 mice were infected with P. berghei ANKA (PbA), treated daily with Ext-Ts, and clinical, biochemical, histological and immunological features of the disease were monitored. It was observed that Ext-Ts presented a dose-dependent ability to control P. falciparum in ihRBCs. In addition, it was demonstrated that Ext-Ts treatment of PbA-infected mice was able to increase survival, prevent neurological signs and decrease parasitaemia at the beginning of infection. These effects were associated with systemically decreased levels of lipids and IFN-γ, ICAM-1, VCAM-1 and CCR5 cerebral expression, preserving blood brain barrier integrity and attenuating the inflammatory lesions in the brain, liver and lungs. These results suggest that Ext-Ts could be a source of immunomodulatory and antimalarial compounds that could improve the treatment of cerebral malaria.
Assuntos
Anti-Inflamatórios/farmacologia , Antimaláricos/farmacologia , Misturas Complexas/farmacologia , Malária Cerebral/tratamento farmacológico , Trichoderma/química , Animais , Anti-Inflamatórios/administração & dosagem , Anti-Inflamatórios/isolamento & purificação , Antimaláricos/administração & dosagem , Antimaláricos/isolamento & purificação , Encéfalo/parasitologia , Encéfalo/patologia , Misturas Complexas/administração & dosagem , Misturas Complexas/isolamento & purificação , Modelos Animais de Doenças , Relação Dose-Resposta a Droga , Eritrócitos/parasitologia , Histocitoquímica , Humanos , Imuno-Histoquímica , Malária Cerebral/parasitologia , Malária Cerebral/patologia , Camundongos Endogâmicos C57BL , Parasitemia/tratamento farmacológico , Plasmodium falciparum/efeitos dos fármacos , Análise de Sobrevida , Resultado do TratamentoRESUMO
Malaria, parasitic disease considered a major health public problem, is caused by Plasmodium protozoan genus and transmitted by the bite of infected female Anopheles mosquito genus. Cerebral malaria (CM) is the most severe presentation of malaria, caused by P. falciparum and responsible for high mortality and enduring development of cognitive deficits which may persist even after cure and cessation of therapy. In the present study we evaluated selected behavioral, neurochemical and neuropathologic parameters after rescue from experimental cerebral malaria caused by P. berghei ANKA in C57BL/6 mice. Behavioral tests showed impaired nest building activity as well as increased marble burying, indicating that natural behavior of mice remains altered even after cure of infection. Regarding the neurochemical data, we found decreased α2/α3 Na+,K+-ATPase activity and increased immunoreactivity of phosphorylated Na+,K+-ATPase at Ser943 in cerebral cortex after CM. In addition, [3H]-Flunitrazepam binding assays revealed a decrease of benzodiazepine/GABAA receptor binding sites in infected animals. Moreover, in hippocampus, dot blot analysis revealed increased levels of protein carbonyls, suggesting occurrence of oxidative damage to proteins. Interestingly, no changes in the neuropathological markers Fluoro-Jade C, Timm staining or IBA-1 were detected. Altogether, present data indicate that behavioral and neurochemical alterations persist even after parasitemia clearance and CM recovery, which agrees with available clinical findings. Some of the molecular mechanisms reported in the present study may underlie the behavioral changes and increased seizure susceptibility that persist after recovery from CM and may help in the future development of therapeutic strategies for CM sequelae.
Assuntos
Comportamento Animal , Malária Cerebral/metabolismo , Malária Cerebral/psicologia , Plasmodium berghei/patogenicidade , Animais , Proteínas de Ligação ao Cálcio/metabolismo , Córtex Cerebral/metabolismo , Feminino , Flunitrazepam/metabolismo , Fluoresceínas/metabolismo , Hipocampo/metabolismo , Malária Cerebral/parasitologia , Malária Cerebral/patologia , Camundongos , Proteínas dos Microfilamentos/metabolismo , Carbonilação Proteica , Ensaio Radioligante , Receptores de GABA-A/metabolismo , Compostos de Prata/metabolismo , ATPase Trocadora de Sódio-Potássio/imunologia , ATPase Trocadora de Sódio-Potássio/metabolismo , Trítio/metabolismoRESUMO
Proinflammatory responses are associated with the severity of cerebral malaria. NO, H2O2, eicosanoid and PPAR-γ are involved in proinflammatory responses, but regulation of these factors is unclear in malaria. This work aimed to compare the expression of eicosanoid-forming-enzymes in cerebral malaria-susceptible CBA and C57BL/6 and -resistant BALB/c mice. Mice were infected with Plasmodium berghei ANKA, and the survival rates and parasitemia curves were assessed. On the sixth day post-infection, cyclooxygenase-2 and 5-lipoxygenase in brain sections were assessed by immunohistochemistry, and, NO, H2O2, lipid bodies, and PPAR-γ expression were assessed in peritoneal macrophages. The C57BL/6 had more severe disease with a lower survival time, higher parasitemia and lower production of plasmodicidal NO and H2O2 molecules than BALB/c. Enhanced COX-2 and 5-LOX expression were observed in brain tissue cells and vessels from C57BL/6 mice, and these mice expressed higher constitutive PPAR-γ levels. There was no translocation of PPAR-γ from cytoplasm to nucleus in macrophages from these mice. CBA mice had enhanced COX-2 expression in brain tissue cells and vessels and also lacked PPAR-γ cytoplasm-to-nucleus translocation. The resistant BALB/c mice presented higher survival time, lower parasitemia and higher NO and H2O2 production on the sixth day post-infection. These mice did not express either COX-2 or 5-LOX in brain tissue cells and vessels. Our data showed that besides the high parasite burden and lack of microbicidal molecules, an imbalance with high COX-2 and 5-LOX eicosanoid expression and a lack of regulatory PPAR-γ cytoplasm-to-nucleus translocation in macrophages were observed in mice that develop cerebral malaria.
Assuntos
Araquidonato 5-Lipoxigenase/metabolismo , Ciclo-Oxigenase 2/metabolismo , Suscetibilidade a Doenças , Gotículas Lipídicas/metabolismo , Malária Cerebral/metabolismo , PPAR gama/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Animais , Araquidonato 5-Lipoxigenase/genética , Encéfalo/metabolismo , Encéfalo/parasitologia , Encéfalo/patologia , Ciclo-Oxigenase 2/genética , Expressão Gênica , Macrófagos Peritoneais/metabolismo , Malária Cerebral/mortalidade , Malária Cerebral/parasitologia , Malária Cerebral/patologia , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos CBA , Microglia/metabolismo , Óxido Nítrico/metabolismo , Nitritos/metabolismo , Plasmodium berghei , Transporte ProteicoRESUMO
Cerebral malaria (CM) is a life-threatening complication of Plasmodium falciparum infection, which can result in long-term cognitive and behavioral deficits despite successful anti-malarial therapy. Due to the substantial social and economic burden of CM, the development of adjuvant therapies is a scientific goal of highest priority. Apart from vascular and immune responses, changes in glutamate system have been reported in CM pathogenesis suggesting a potential therapeutic target. Based on that, we hypothesized that interventions in the glutamatergic system induced by blockage of N-methyl-D-aspartate (NMDA) receptors could attenuate experimental CM long-term cognitive and behavioral outcomes. Before the development of evident CM signs, susceptible mice infected with Plasmodium berghei ANKA (PbA) strain were initiated on treatment with dizocilpine maleate (MK801, 0.5 mg/kg), a noncompetitive NMDA receptor antagonist. On day 5 post-infection, mice were treated orally with a 10-day course chloroquine (CQ, 30 mg/kg). Control mice also received saline, CQ or MK801 + CQ therapy. After 10 days of cessation of CQ treatment, magnetic resonance images (MRI), behavioral and immunological assays were performed. Indeed, MK801 combined with CQ prevented long-term memory impairment and depressive-like behavior following successful PbA infection resolution. In addition, MK801 also modulated the immune system by promoting a balance of TH1/TH2 response and upregulating neurotrophic factors levels in the frontal cortex and hippocampus. Moreover, hippocampus abnormalities observed by MRI were partially prevented by MK801 treatment. Our results indicate that NMDA receptor antagonists can be neuroprotective in CM and could be a valuable adjuvant strategy for the management of the long-term impairment observed in CM.
Assuntos
Comportamento Animal , Cognição , Maleato de Dizocilpina/uso terapêutico , Antagonistas de Aminoácidos Excitatórios/uso terapêutico , Malária Cerebral/tratamento farmacológico , Malária Cerebral/fisiopatologia , Fármacos Neuroprotetores/uso terapêutico , Receptores de Glutamato/metabolismo , Animais , Ansiedade/complicações , Ansiedade/tratamento farmacológico , Ansiedade/fisiopatologia , Comportamento Animal/efeitos dos fármacos , Cognição/efeitos dos fármacos , Citocinas/sangue , Citocinas/metabolismo , Depressão/complicações , Depressão/tratamento farmacológico , Depressão/fisiopatologia , Maleato de Dizocilpina/farmacologia , Antagonistas de Aminoácidos Excitatórios/farmacologia , Feminino , Ácido Glutâmico/metabolismo , Hipocampo/metabolismo , Hipocampo/patologia , Leucócitos/metabolismo , Imageamento por Ressonância Magnética , Malária Cerebral/complicações , Malária Cerebral/patologia , Memória de Curto Prazo/efeitos dos fármacos , Camundongos Endogâmicos C57BL , Fatores de Crescimento Neural/metabolismo , Fármacos Neuroprotetores/farmacologia , Tamanho do Órgão , Parasitemia/sangue , Parasitemia/complicações , Parasitemia/patologia , Fenótipo , Plasmodium berghei/efeitos dos fármacos , Receptores de N-Metil-D-Aspartato/antagonistas & inibidores , Receptores de N-Metil-D-Aspartato/metabolismo , Análise de Sobrevida , Regulação para CimaRESUMO
Dendritic cells have an important role in immune surveillance. After being exposed to microbial components, they migrate to secondary lymphoid organs and activate T lymphocytes. Here we show that during mouse malaria, splenic inflammatory monocytes differentiate into monocyte-derived dendritic cells (MO-DCs), which are CD11b+F4/80+CD11c+MHCIIhighDC-SIGNhighLy6c+ and express high levels of CCR5, CXCL9 and CXCL10 (CCR5+CXCL9/10+ MO-DCs). We propose that malaria-induced splenic MO-DCs take a reverse migratory route. After differentiation in the spleen, CCR5+CXCL9/10+ MO-DCs traffic to the brain in a CCR2-independent, CCR5-dependent manner, where they amplify the influx of CD8+ T lymphocytes, leading to a lethal neuropathological syndrome.
Assuntos
Encéfalo/imunologia , Linfócitos T CD8-Positivos/imunologia , Células Dendríticas/fisiologia , Malária Cerebral/imunologia , Baço/fisiologia , Animais , Antígenos de Protozoários/imunologia , Encéfalo/citologia , Encéfalo/patologia , Diferenciação Celular/imunologia , Quimiocina CXCL10/metabolismo , Quimiocina CXCL9/metabolismo , Modelos Animais de Doenças , Humanos , Malária Cerebral/parasitologia , Malária Cerebral/patologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Monócitos/citologia , Plasmodium berghei/imunologia , Receptores CCR5/metabolismo , Baço/citologiaRESUMO
INTRODUCTION: Malaria is the most relevant parasitic disease worldwide, and still accounts for 1 million deaths each year. Since current antimalarial drugs are unable to prevent death in severe cases, new therapeutic strategies have been developed. Mesenchymal stromal cells (MSC) confer host resistance against malaria; however, thus far, no study has evaluated the therapeutic effects of MSC therapy on brain and distal organ damage in experimental cerebral malaria. METHODS: Forty C57BL/6 mice were injected intraperitoneally with 5 × 10(6) Plasmodium berghei-infected erythrocytes or saline. After 24 h, mice received saline or bone marrow (BM)-derived MSC (1x10(5)) intravenously and were housed individually in metabolic cages. After 4 days, lung and kidney morphofunction; cerebrum, spleen, and liver histology; and markers associated with inflammation, fibrogenesis, and epithelial and endothelial cell damage in lung tissue were analyzed. RESULTS: In P. berghei-infected mice, BM-MSCs: 1) reduced parasitemia and mortality; 2) increased phagocytic neutrophil content in brain, even though BM-MSCs did not affect the inflammatory process; 3) decreased malaria pigment detection in spleen, liver, and kidney; 4) reduced hepatocyte derangement, with an increased number of Kupffer cells; 5) decreased kidney damage, without effecting significant changes in serum creatinine levels or urinary flow; and 6) reduced neutrophil infiltration, interstitial edema, number of myofibroblasts within interstitial tissue, and collagen deposition in lungs, resulting in decreased lung static elastance. These morphological and functional changes were not associated with changes in levels of tumor necrosis factor-α, keratinocyte-derived chemokine (KC, a mouse analog of interleukin-8), or interferon-γ, which remained increased and similar to those of P. berghei animals treated with saline. BM-MSCs increased hepatocyte growth factor but decreased VEGF in the P. berghei group. CONCLUSIONS: BM-MSC treatment increased survival and reduced parasitemia and malaria pigment accumulation in spleen, liver, kidney, and lung, but not in brain. The two main organs associated with worse prognosis in malaria, lung and kidney, sustained less histological damage after BM-MSC therapy, with a more pronounced improvement in lung function.