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Moreira DR, Uberti ACMG, Gomes ARQ, Ferreira MES, da Silva Barbosa A, Varela ELP, Dolabela MF, Percário S. Dexamethasone increased the survival rate in Plasmodium berghei-infected mice. Sci Rep 2021; 11:2623. [PMID: 33514836 PMCID: PMC7846581 DOI: 10.1038/s41598-021-82032-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Accepted: 01/11/2021] [Indexed: 01/30/2023] Open
Abstract
The present study aimed to evaluate the effects of dexamethasone on the redox status, parasitemia evolution, and survival rate of Plasmodium berghei-infected mice. Two-hundred and twenty-five mice were infected with Plasmodium berghei and subjected to stimulation or inhibition of NO synthesis. The stimulation of NO synthesis was performed through the administration of L-arginine, while its inhibition was made by the administration of dexamethasone. Inducible NO synthase (iNOS) inhibition by dexamethasone promoted an increase in the survival rate of P. berghei-infected mice, and the data suggested the participation of oxidative stress in the brain as a result of plasmodial infection, as well as the inhibition of brain NO synthesis, which promoted the survival rate of almost 90% of the animals until the 15th day of infection, with possible direct interference of ischemia and reperfusion syndrome, as seen by increased levels of uric acid. Inhibition of brain iNOS by dexamethasone caused a decrease in parasitemia and increased the survival rate of infected animals, suggesting that NO synthesis may stimulate a series of compensatory redox effects that, if overstimulated, may be responsible for the onset of severe forms of malaria.
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Affiliation(s)
- Danilo Reymão Moreira
- grid.271300.70000 0001 2171 5249Oxidative Stress Research Laboratory, Institute of Biological Sciences, Federal University of Pará, Av. Augusto Corrêa, 01, Belém, PA 66075-110 Brazil
| | - Ana Carolina Musa Gonçalves Uberti
- grid.271300.70000 0001 2171 5249Oxidative Stress Research Laboratory, Institute of Biological Sciences, Federal University of Pará, Av. Augusto Corrêa, 01, Belém, PA 66075-110 Brazil
| | - Antonio Rafael Quadros Gomes
- grid.271300.70000 0001 2171 5249Oxidative Stress Research Laboratory, Institute of Biological Sciences, Federal University of Pará, Av. Augusto Corrêa, 01, Belém, PA 66075-110 Brazil
| | - Michelli Erica Souza Ferreira
- grid.411204.20000 0001 2165 7632Laboratory of Pathophysiology and Therapeutic Research, Centro de Ciências Sociais Saúde e Tecnologia – CCSST, Federal University of Maranhão, Campus Avançado - Bom Jesus, Prédio de Medicina, Av. da Universidade, S/N, Imperatriz, MA 65915-240 Brazil
| | - Aline da Silva Barbosa
- grid.271300.70000 0001 2171 5249Oxidative Stress Research Laboratory, Institute of Biological Sciences, Federal University of Pará, Av. Augusto Corrêa, 01, Belém, PA 66075-110 Brazil
| | - Everton Luiz Pompeu Varela
- grid.271300.70000 0001 2171 5249Oxidative Stress Research Laboratory, Institute of Biological Sciences, Federal University of Pará, Av. Augusto Corrêa, 01, Belém, PA 66075-110 Brazil
| | - Maria Fani Dolabela
- grid.271300.70000 0001 2171 5249Institute of Health Sciences, Federal University of Pará, Av. Augusto Corrêa, 01, Belém, PA 66075-110 Brazil
| | - Sandro Percário
- grid.271300.70000 0001 2171 5249Oxidative Stress Research Laboratory, Institute of Biological Sciences, Federal University of Pará, Av. Augusto Corrêa, 01, Belém, PA 66075-110 Brazil
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Gun SY, Claser C, Teo TH, Howland SW, Poh CM, Chye RRY, Ng LFP, Rénia L. Interferon regulatory factor 1 is essential for pathogenic CD8+ T cell migration and retention in the brain during experimental cerebral malaria. Cell Microbiol 2018; 20:e12819. [PMID: 29281764 DOI: 10.1111/cmi.12819] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Revised: 10/15/2017] [Accepted: 11/26/2017] [Indexed: 12/22/2022]
Abstract
Host immune response has a key role in controlling the progression of malaria infection. In the well-established murine model of experimental cerebral malaria (ECM) with Plasmodium berghei ANKA infection, proinflammatory Th1 and CD8+ T cell response are essential for disease development. Interferon regulatory factor 1 (IRF1) is a transcription factor that promotes Th1 responses, and its absence was previously shown to protect from ECM death. Yet the exact mechanism of protection remains unknown. Here we demonstrated that IRF1-deficient mice (IRF1 knockout) were protected from ECM death despite displaying early neurological signs. Resistance to ECM death was a result of reduced parasite sequestration and pathogenic CD8+ T cells in the brain. Further analysis revealed that IRF1 deficiency suppress interferon-γ production and delayed CD8+ T cell proliferation. CXCR3 expression was found to be decreased in pathogenic CD8+ T cells, which limited their migration to the brain. In addition, reduced expression of adhesion molecules by brain endothelial cells hampered leucocyte retention in the brain. Taken together, these factors limited sequestration of pathogenic CD8+ T cells and consequently its ability to induce extensive damage to the blood-brain barrier.
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Affiliation(s)
- Sin Yee Gun
- Singapore Immunology Network, Agency for Science, Technology and Research (A*STAR), Singapore.,Department of Microbiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Carla Claser
- Singapore Immunology Network, Agency for Science, Technology and Research (A*STAR), Singapore
| | - Teck Hui Teo
- Singapore Immunology Network, Agency for Science, Technology and Research (A*STAR), Singapore
| | - Shanshan W Howland
- Singapore Immunology Network, Agency for Science, Technology and Research (A*STAR), Singapore
| | - Chek Meng Poh
- Singapore Immunology Network, Agency for Science, Technology and Research (A*STAR), Singapore.,Department of Microbiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Rebecca Ren Ying Chye
- Singapore Immunology Network, Agency for Science, Technology and Research (A*STAR), Singapore.,Department of Biological Science, National University of Singapore, Singapore
| | - Lisa F P Ng
- Singapore Immunology Network, Agency for Science, Technology and Research (A*STAR), Singapore
| | - Laurent Rénia
- Singapore Immunology Network, Agency for Science, Technology and Research (A*STAR), Singapore.,Department of Microbiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
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3
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Pai S, Qin J, Cavanagh L, Mitchell A, El-Assaad F, Jain R, Combes V, Hunt NH, Grau GER, Weninger W. Real-time imaging reveals the dynamics of leukocyte behaviour during experimental cerebral malaria pathogenesis. PLoS Pathog 2014; 10:e1004236. [PMID: 25033406 PMCID: PMC4102563 DOI: 10.1371/journal.ppat.1004236] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2013] [Accepted: 05/23/2014] [Indexed: 02/02/2023] Open
Abstract
During experimental cerebral malaria (ECM) mice develop a lethal neuropathological syndrome associated with microcirculatory dysfunction and intravascular leukocyte sequestration. The precise spatio-temporal context in which the intravascular immune response unfolds is incompletely understood. We developed a 2-photon intravital microscopy (2P-IVM)-based brain-imaging model to monitor the real-time behaviour of leukocytes directly within the brain vasculature during ECM. Ly6Chi monocytes, but not neutrophils, started to accumulate in the blood vessels of Plasmodium berghei ANKA (PbA)-infected MacGreen mice, in which myeloid cells express GFP, one to two days prior to the onset of the neurological signs (NS). A decrease in the rolling speed of monocytes, a measure of endothelial cell activation, was associated with progressive worsening of clinical symptoms. Adoptive transfer experiments with defined immune cell subsets in recombinase activating gene (RAG)-1-deficient mice showed that these changes were mediated by Plasmodium-specific CD8+ T lymphocytes. A critical number of CD8+ T effectors was required to induce disease and monocyte adherence to the vasculature. Depletion of monocytes at the onset of disease symptoms resulted in decreased lymphocyte accumulation, suggesting reciprocal effects of monocytes and T cells on their recruitment within the brain. Together, our studies define the real-time kinetics of leukocyte behaviour in the central nervous system during ECM, and reveal a significant role for Plasmodium-specific CD8+ T lymphocytes in regulating vascular pathology in this disease. Cerebral malaria (CM) is a severe complication of Plasmodium falciparum infection that takes a significant toll on human life. Blockage of the brain blood vessels contributes to the clinical signs of CM, however we know little about the precise pathological events that lead to this disease. To this end, studies in Plasmodium-infected mice, that also develop a similar fatal disease, have proven useful. These studies have revealed an important role for leukocytes not so much in protecting but rather promoting pathology in the brain. To better understand leukocyte behaviour during experimental CM, we established a brain-imaging model that allows us to ‘peek’ into the brain of living mice and watch immunological events as they unfold. We found that worsening of disease was accompanied by an accumulation of monocytes in the blood vessels. Monocyte accumulation was regulated by activated CD8+ T cells but only when present in critical numbers. Monocyte depletion resulted in reduced T cell trafficking to the brain, but this did not result in improved disease outcome. Our studies reveal the orchestration of leukocyte accumulation in real time during CM, and demonstrate that CD8+ T cells play a crucial role in promoting clinical signs in this disease.
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Affiliation(s)
- Saparna Pai
- Immune Imaging Laboratory, The Centenary Institute, Newtown, Sydney, New South Wales, Australia
- Sydney Medical School, University of Sydney, Sydney, New South Wales, Australia
- * E-mail: (SP); (WW)
| | - Jim Qin
- Immune Imaging Laboratory, The Centenary Institute, Newtown, Sydney, New South Wales, Australia
| | - Lois Cavanagh
- Immune Imaging Laboratory, The Centenary Institute, Newtown, Sydney, New South Wales, Australia
- Sydney Medical School, University of Sydney, Sydney, New South Wales, Australia
| | - Andrew Mitchell
- Immune Imaging Laboratory, The Centenary Institute, Newtown, Sydney, New South Wales, Australia
| | - Fatima El-Assaad
- Vascular Immunology Unit, Discipline of Pathology, Sydney Medical School, University of Sydney, Camperdown, Sydney, New South Wales, Australia
| | - Rohit Jain
- Immune Imaging Laboratory, The Centenary Institute, Newtown, Sydney, New South Wales, Australia
- Sydney Medical School, University of Sydney, Sydney, New South Wales, Australia
| | - Valery Combes
- Sydney Medical School, University of Sydney, Sydney, New South Wales, Australia
- Vascular Immunology Unit, Discipline of Pathology, Sydney Medical School, University of Sydney, Camperdown, Sydney, New South Wales, Australia
| | - Nicholas H. Hunt
- Sydney Medical School, University of Sydney, Sydney, New South Wales, Australia
- Molecular Immunopathology Unit, Discipline of Pathology, Sydney Medical School and Bosch Institute, University of Sydney, Camperdown, Sydney, New South Wales, Australia
| | - Georges E. R. Grau
- Sydney Medical School, University of Sydney, Sydney, New South Wales, Australia
- Vascular Immunology Unit, Discipline of Pathology, Sydney Medical School, University of Sydney, Camperdown, Sydney, New South Wales, Australia
| | - Wolfgang Weninger
- Immune Imaging Laboratory, The Centenary Institute, Newtown, Sydney, New South Wales, Australia
- Discipline of Dermatology, University of Sydney, Sydney, New South Wales, Australia
- Department of Dermatology, Royal Prince Alfred Hospital, Camperdown, Sydney, New South Wales, Australia
- * E-mail: (SP); (WW)
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Pathogenesis of malaria-associated acute respiratory distress syndrome. Trends Parasitol 2013; 29:346-58. [PMID: 23742967 DOI: 10.1016/j.pt.2013.04.006] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Revised: 04/26/2013] [Accepted: 04/26/2013] [Indexed: 12/13/2022]
Abstract
Malaria-associated acute respiratory distress syndrome (MA-ARDS) is an increasingly reported, often lethal, and incompletely understood complication of malaria. We discuss and compare the pathogenesis of MA-ARDS in patients and in different murine models, including recent models without cerebral involvement, and summarize the roles of different leukocyte subclasses, adhesion molecules, cytokines, and chemokines. In patients as well as in mice, severe edema and impaired gas exchange are associated with abundant inflammatory infiltrates consisting of mainly mononuclear cells and parasite sequestration, and the pathogenesis appears different from cerebral malaria (CM). Experimental anti-inflammatory interventions are successful in mice and remain to be validated in patients.
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Schmidt KE, Schumak B, Specht S, Dubben B, Limmer A, Hoerauf A. Induction of pro-inflammatory mediators in Plasmodium berghei infected BALB/c mice breaks blood-brain-barrier and leads to cerebral malaria in an IL-12 dependent manner. Microbes Infect 2011; 13:828-36. [PMID: 21609776 DOI: 10.1016/j.micinf.2011.04.006] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2010] [Revised: 03/24/2011] [Accepted: 04/18/2011] [Indexed: 01/07/2023]
Abstract
A severe complication of Plasmodium infection is cerebral malaria, a condition mainly attributed to overwhelming inflammatory immune reactions of the host. Murine models differing in susceptibility to experimental cerebral malaria (ECM) allow detailed studies of the host response. We show that ECM- resistant BALB/c mice were driven into interferon gamma- and IL-12-dependent ECM and subsequent death if they received CpG-oligonucleotides after Plasmodium berghei ANKA (PbA) infection. CpG application triggered production of pro-inflammatory cytokines systemically as well in spleen and brain and induced neuropathological symptoms, leading to increased mortality. Experiments with genetically deficient mice confirmed the role of IFN-γ and IL-12 during CpG-triggered immunopathology. Furthermore, the application of CpG and downstream production of pro-inflammatory cytokines contributed to the break down of the blood brain barrier visualized by Evan's Blue, comparable to PbA-infected C57BL/6 mice. Taken together, resistance of BALB/c mice towards ECM development could be altered through induction of pro-inflammatory cytokines by CpG. Therefore, approaches discussed earlier to induce pro-inflammatory immune reactions for malaria protection should be considered with caution.
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Affiliation(s)
- Kim E Schmidt
- Institute of Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Sigmund-Freud-Strasse 25, 53105 Bonn, Germany
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Waknine-Grinberg JH, Hunt N, Bentura-Marciano A, McQuillan JA, Chan HW, Chan WC, Barenholz Y, Haynes RK, Golenser J. Artemisone effective against murine cerebral malaria. Malar J 2010; 9:227. [PMID: 20691118 PMCID: PMC2928250 DOI: 10.1186/1475-2875-9-227] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2010] [Accepted: 08/09/2010] [Indexed: 11/12/2022] Open
Abstract
Background Artemisinins are the newest class of drug approved for malaria treatment. Due to their unique mechanism of action, rapid effect on Plasmodium, and high efficacy in vivo, artemisinins have become essential components of malaria treatment. Administration of artemisinin derivatives in combination with other anti-plasmodials has become the first-line treatment for uncomplicated falciparum malaria. However, their efficiency in cases of cerebral malaria (CM) remains to be determined. Methods The efficacy of several artemisinin derivatives for treatment of experimental CM was evaluated in ICR or C57BL/6 mice infected by Plasmodium berghei ANKA. Both mouse strains serve as murine models for CM. Results Artemisone was the most efficient drug tested, and could prevent death even when administered at relatively late stages of cerebral pathogenesis. No parasite resistance to artemisone was detected in recrudescence. Co-administration of artemisone together with chloroquine was more effective than monotherapy with either drug, and led to complete cure. Artemiside was even more effective than artemisone, but this substance has yet to be submitted to preclinical toxicological evaluation. Conclusions Altogether, the results support the use of artemisone for combined therapy of CM.
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Affiliation(s)
- Judith H Waknine-Grinberg
- Department of Microbiology and Molecular Genetics, The Hebrew University of Jerusalem, Jerusalem, 91120, Israel
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7
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Van den Steen PE, Geurts N, Deroost K, Van Aelst I, Verhenne S, Heremans H, Van Damme J, Opdenakker G. Immunopathology and Dexamethasone Therapy in a New Model for Malaria-associated Acute Respiratory Distress Syndrome. Am J Respir Crit Care Med 2010; 181:957-68. [DOI: 10.1164/rccm.200905-0786oc] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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8
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Cerebral malaria: why experimental murine models are required to understand the pathogenesis of disease. Parasitology 2009; 137:755-72. [PMID: 20028608 DOI: 10.1017/s0031182009991715] [Citation(s) in RCA: 165] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Cerebral malaria is a life-threatening complication of malaria infection. The pathogenesis of cerebral malaria is poorly defined and progress in understanding the condition is severely hampered by the inability to study in detail, ante-mortem, the parasitological and immunological events within the brain that lead to the onset of clinical symptoms. Experimental murine models have been used to investigate the sequence of events that lead to cerebral malaria, but there is significant debate on the merits of these models and whether their study is relevant to human disease. Here we review the current understanding of the parasitological and immunological events leading to human and experimental cerebral malaria, and explain why we believe that studies with experimental models of CM are crucial to define the pathogenesis of the condition.
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Protection against cerebral malaria by the low-molecular-weight thiol pantethine. Proc Natl Acad Sci U S A 2008; 105:1321-6. [PMID: 18195363 DOI: 10.1073/pnas.0706867105] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We report that administration of the low-molecular-weight thiol pantethine prevented the cerebral syndrome in Plasmodium berghei ANKA-infected mice. The protection was associated with an impairment of the host response to the infection, with in particular a decrease of circulating microparticles and preservation of the blood-brain barrier integrity. Parasite development was unaffected. Pantethine modulated one of the early steps of the inflammation-coagulation cascade, i.e., the transbilayer translocation of phosphatidylserine at the cell surface that we demonstrated on red blood cells and platelets. In this, pantethine mimicked the inactivation of the ATP-binding-cassette transporter A1 (ABCA1), which also prevents the cerebral syndrome in this malaria model. However, pantethine acts through a different pathway, because ABCA1 activity was unaffected by the treatment. The mechanisms of pantethine action were investigated, using the intact molecule and its constituents. The disulfide group (oxidized form) is necessary to lower the platelet response to activation by thrombin and collagen. Thio-sensitive mechanisms are also involved in the impairment of microparticle release by TNF-activated endothelial cells. In isolated cells, the effects were obtained by cystamine that lacks the pantothenic moiety of the molecule; however, the complete molecule is necessary to protect against cerebral malaria. Pantethine is well tolerated, and it has already been administered in other contexts to man with limited side effects. Therefore, trials of pantethine treatment in adjunctive therapy for severe malaria are warranted.
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Finney CA, Liles WC, Kain KC. Severe malaria and host response: time for a paradigm shift in therapeutic strategies to improve clinical outcome. ACTA ACUST UNITED AC 2007. [DOI: 10.1016/j.ddmec.2008.02.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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11
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Golenser J, Waknine JH, Krugliak M, Hunt NH, Grau GE. Current perspectives on the mechanism of action of artemisinins. Int J Parasitol 2006; 36:1427-41. [PMID: 17005183 DOI: 10.1016/j.ijpara.2006.07.011] [Citation(s) in RCA: 191] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2006] [Revised: 07/24/2006] [Accepted: 07/28/2006] [Indexed: 10/24/2022]
Abstract
Artemisinin derivatives are the most recent single drugs approved and introduced for public antimalarial treatment. Although their recommended use is for treatment of Plasmodium falciparum infection, these drugs also act against other parasites, as well as against tumor cells. The mechanisms of action attributed to artemisinin include interference with parasite transport proteins, disruption of parasite mitochondrial function, modulation of host immune function and inhibition of angiogenesis. Artemisinin combination therapies are currently the preferred treatment for malaria. These combinations may prevent the induction of parasite drug resistance. However, in view of the multiple mechanisms involved, especially when additional drugs are used, the combined therapy should be carefully examined for antagonistic effects. It is now a general theory that the crucial mechanism is interference with plasmodial SERCA. Therefore, future development of resistance may be associated with overproduction or mutations of this transporter. However, a general mechanism, such as alterations in general drug transport pathways, is feasible. In this article, we review the evidence for each mechanism of action suggested.
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Affiliation(s)
- Jacob Golenser
- Department of Parasitology - The Kuvin Centre for the Study of Infectious and Tropical Diseases, The Hebrew University of Jerusalem, Jerusalem 91120, Israel.
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12
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Hunt NH, Golenser J, Chan-Ling T, Parekh S, Rae C, Potter S, Medana IM, Miu J, Ball HJ. Immunopathogenesis of cerebral malaria. Int J Parasitol 2006; 36:569-82. [PMID: 16678181 DOI: 10.1016/j.ijpara.2006.02.016] [Citation(s) in RCA: 181] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2005] [Revised: 02/09/2006] [Accepted: 02/17/2006] [Indexed: 01/20/2023]
Abstract
Malaria is one of the most important global health problems, potentially affecting more than one third of the world's population. Cerebral malaria (CM) is a deadly complication of Plasmodium falciparum infection, yet its pathogenesis remains incompletely understood. In this review, we discuss some of the principal pathogenic events that have been described in murine models of the disease and relate them to the human condition. One of the earliest events in CM pathogenesis appears to be a mild increase in the permeability to protein of the blood-brain barrier. Recent studies have shown a role for CD8+T cells in mediating damage to the microvascular endothelium and this damage can result in the leakage of cytokines, malaria antigens and other potentially harmful molecules across the blood-brain barrier into the cerebral parenchyma. We suggest that this, in turn, leads to the activation of microglia and the activation and apoptosis of astrocytes. The role of hypoxia in the pathogenesis of cerebral malaria is also discussed, with particular reference to the local reduction of oxygen consumption in the brain as a consequence of vascular obstruction, to cytokine-driven changes in glucose metabolism, and to cytopathic hypoxia. Interferon-gamma, a cytokine known to be produced in malaria infection, induces increased expression, by microvascular endothelial cells, of the haem enzyme indoleamine 2,3-dioxygenase, the first enzyme in the kynurenine pathway of tryptophan metabolism. Enhanced indoleamine 2,3-dioxygenase expression leads to increased production of a range of biologically active metabolites that may be part of a tissue protective response. Damage to astrocytes may result in reduced production of the neuroprotectant molecule kynurenic acid, leading to a decrease in its ratio relative to the neuroexcitotoxic molecule quinolinic acid, which might contribute to some of the neurological symptoms of cerebral malaria. Lastly, we discuss the role of other haem enzymes, cyclooxygenase-2, inducible nitric oxide synthase and haem oxygenase-1, as potentially being components of mechanisms that protect host tissue against the effects of cytokine- and leukocyte-mediated stress induced by malaria infection.
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Affiliation(s)
- Nicholas H Hunt
- Molecular Immunopathology Unit, Institute for Biomedical Research, University of Sydney, Sydney, NSW, Australia.
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13
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Idro R, Jenkins NE, Newton CRJC. Pathogenesis, clinical features, and neurological outcome of cerebral malaria. Lancet Neurol 2006; 4:827-40. [PMID: 16297841 DOI: 10.1016/s1474-4422(05)70247-7] [Citation(s) in RCA: 313] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Cerebral malaria is the most severe neurological complication of Plasmodium falciparum malaria. Even though this type of malaria is most common in children living in sub-Saharan Africa, it should be considered in anybody with impaired consciousness that has recently travelled in a malaria-endemic area. Cerebral malaria has few specific features, but there are differences in clinical presentation between African children and non-immune adults. Subsequent neurological impairments are also most common and severe in children. Sequestration of infected erythrocytes within cerebral blood vessels seems to be an essential component of the pathogenesis. However, other factors such as convulsions, acidosis, or hypoglycaemia can impair consciousness. In this review, we describe the clinical features and epidemiology of cerebral malaria. We highlight recent insights provided by ex-vivo work on sequestration and examination of pathological specimens. We also summarise recent studies of persisting neurocognitive impairments in children who survive cerebral malaria and suggest areas for further research.
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Affiliation(s)
- Richard Idro
- Centre for Geographic Medicine Research-Coast, Kenya Medical Research Insitute, Kilifi, Kenya.
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14
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Kumar KA, Babu PP. CaM kinase II-alpha activity, levels and Ca/calmodulin dependent phosphorylation of substrate proteins in mice brain during fatal murine cerebral malaria. Neurosci Lett 2003; 336:121-5. [PMID: 12499055 DOI: 10.1016/s0304-3940(02)01100-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The activity and levels of CaM kinase II-alpha was investigated in the cytosolic and membrane fraction of mice cerebral cortex and cerebellum using an experimental model of fatal murine cerebral malaria (FMCM). In parallel, Ca(2+)/Calmodulin dependent phosphorylation of target substrate proteins was studied using syntide-2 as substrate. Pathology of FMCM resulted in decreased CaM kinase-II activity in both cortex and cerebellum though western analysis revealed no appreciable changes in the levels of CaM kinase-II alpha in cytosol and membrane fractions from control and cerebral malaria infected brain. Given the abundant expression of Cam kinase-II in neuronal tissue, its significance in neurotransmitter release and synthesis and signal transduction during apoptosis, decreased levels of enzyme activity and altered phosphorylation of substrate proteins by CaM kinase II may serve as important cues in understanding the CaM kinase signal transduction events central to neurological disorders during FMCM.
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Affiliation(s)
- Kota Arun Kumar
- Department of Animal Sciences, School of Life Sciences, University of Hyderabad, Hyderabad -500 046, India
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Kumar KA, Babu PP. Mitochondrial anomalies are associated with the induction of intrinsic cell death proteins-Bcl(2), Bax, cytochrome-c and p53 in mice brain during experimental fatal murine cerebral malaria. Neurosci Lett 2002; 329:319-23. [PMID: 12183040 DOI: 10.1016/s0304-3940(02)00470-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The levels of apoptosis associated proteins Bcl(2), Bax, cytochrome-c and p53 was investigated in mice cerebral cortex and cerebellum, using an experimental model of fatal murine cerebral malaria (FMCM). Owing to the activation of events central to mitochondrial dysfunctions, we monitored the structural integrity of mitochondria in cerebral malaria (CM) infected brain tissue by transmission EM (TEM) studies. Western blot analysis revealed the induction of Bcl(2), Bax, cytochrome-c and p53 in both cortex and cerebellum. The TEM studies revealed extensive vacuolation and swelling of mitochondria in infected brain suggestive of a late stage of degeneration. Our results underscore the activation of an intrinsic cell death pathway as evinced by the induction of mitochondria associated apoptotic proteins Bcl(2), Bax and cytochrome-c and further envisages the induction of p53 as a possible continuation of the post receptor signaling events associated with tumor necrosis factor induction following inflammatory responses during CM. These findings may be crucial to mitochondrial dysfunctions underlying the pathology of FMCM.
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Affiliation(s)
- Kota Arun Kumar
- Department of Animal Sciences, School of Life Sciences, University of Hyderabad, Hyderabad 500 046, India
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16
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Sanni LA, Rae C, Maitland A, Stocker R, Hunt NH. Is ischemia involved in the pathogenesis of murine cerebral malaria? THE AMERICAN JOURNAL OF PATHOLOGY 2001; 159:1105-12. [PMID: 11549603 PMCID: PMC1850448 DOI: 10.1016/s0002-9440(10)61786-5] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 05/14/2001] [Indexed: 12/01/2022]
Abstract
Sequestration of parasitized erythrocytes in the central nervous system microcirculation and increased cerebrospinal fluid lactate are prominent features of cerebral malaria (CM), suggesting that sequestration causes mechanical obstruction and ischemia. To examine the potential role of ischemia in the pathogenesis of CM, Plasmodium berghei ANKA (PbA) infection in CBA mice was compared to infection with P. berghei K173 (PbK) which does not cause CM (the non-CM model, NCM). Cerebral metabolite pools were measured by (1)H nuclear magnetic resonance spectroscopy during PbA and PbK infections. Lactate and alanine concentrations increased significantly at the terminal stage of CM, but not in NCM mice at any stage. These changes did not correlate with parasitemia. Brain NAD/NADH ratio was unchanged in CM and NCM mice at any time studied, but the total NAD pool size decreased significantly in the CM mice on day 7 after inoculation. Brain levels of glutamine and several essential amino acids were increased significantly in CM mice. There was a significant linear correlation between the time elapsed after infection and small, progressive decreases in the cell density/cell viability markers glycerophosphocholine and N-acetylaspartate in CM, indicative of gradual loss of cell viability. The metabolite changes followed a different pattern, with a sudden significant alteration in the levels of lactate, alanine, and glutamine at the time of terminal CM. In NCM, there were significant decreases with time of glutamate, the osmolyte myo-inositol, and glycerophosphocholine. These results are consistent with an ischemic change in the metabolic pattern of the brain in CM mice, whereas in NCM mice the changes were more consistent with hypoxia without vascular obstruction. Mild obstructive ischemia is a likely cause of the metabolic changes during CM, but a role for immune cell effector molecules cannot be ruled out.
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Affiliation(s)
- L A Sanni
- Department of Pathology, University of Sydney, Sydney, Australia
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Medana IM, Chaudhri G, Chan-Ling T, Hunt NH. Central nervous system in cerebral malaria: 'Innocent bystander' or active participant in the induction of immunopathology? Immunol Cell Biol 2001; 79:101-20. [PMID: 11264703 DOI: 10.1046/j.1440-1711.2001.00995.x] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Cerebral malaria (CM) is a major life-threatening complication of Plasmodium falciparum infection in humans, responsible for up to 2 million deaths annually. The mechanisms underlying the fatal cerebral complications are still not fully understood. Many theories exist on the aetiology of human CM. The sequestration hypo-thesis suggests that adherence of parasitized erythrocytes to the cerebral vasculature leads to obstruction of the microcirculation, anoxia or metabolic disturbances affecting brain function, resulting in coma. This mechanism alone seems insufficient to explain all the known features of CM. In this review we focus on another major school of thought, that CM is the result of an over-vigorous immune response originally evolved for the protection of the host. Evidence in support of this second hypothesis comes from studies in murine malaria models in which T cells, monocytes, adhesion molecules and cytokines, have been implicated in the development of the cerebral complications. Recent studies of human CM also indicate a role for the immune system in the neurological complications. However, it is likely that multiple mechanisms are involved in the induction of cerebral complications and both the presence of parasitized erythrocytes in the central nervous system (CNS) and immunopathological processes contribute to the pathogenesis of CM. Most studies examining immunopathological responses in CM have focused on reactions occurring primarily in the systemic circulation. However, these also do not fully account for the development of cerebral complications in CM. In this review we summarize results from human and mouse studies that demonstrate morphological and functional changes in the resident glial cells of the CNS. The degree of immune activation and degeneration of glial cells was shown to reflect the extent of neurological complications in murine cerebral malaria. From these results we highlight the need to consider the potentially important contribution within the CNS of glia and their secreted products, such as cytokines, in the development of human CM.
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Affiliation(s)
- I M Medana
- Departments of Pathology and Anatomy/Histology, University of Sydney, New South Wales, Australia
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Medana IM, Chan-Ling T, Hunt NH. Reactive changes of retinal microglia during fatal murine cerebral malaria: effects of dexamethasone and experimental permeabilization of the blood-brain barrier. THE AMERICAN JOURNAL OF PATHOLOGY 2000; 156:1055-65. [PMID: 10702421 PMCID: PMC1876828 DOI: 10.1016/s0002-9440(10)64973-5] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Microglial activation and redistribution toward blood vessels are some of the earliest observable events occurring within the central nervous system (CNS) during fatal murine cerebral malaria (FMCM). To investigate stimuli that might modulate microglial reactivity during FMCM we have performed two experimental manipulations and observed microglial responses in retinal whole mounts. First, to determine whether increased blood-brain barrier (BBB) permeability in the absence of the malaria parasite initiates the microglial changes, BBB function was compromised experimentally by intracarotid injection of arabinose and retinae were examined 12, 24, or 36 hours later. Second, to determine whether the immune response against the malaria parasite modulates microglial reactivity, infected mice were treated with dexamethasone before day 4 postinoculation. This treatment regime ameliorates cerebral complications without affecting parasite growth. We observed that increased BBB permeability was sufficient to elicit thickening of microglial processes and redistribution of microglia toward the vasculature, characteristic of the early stages of FMCM. However, despite the presence of plasma constituents in the CNS for up to 36 hours, microglia with amoeboid and vacuolated morphology were not observed. Dexamethasone treatment inhibited the up-regulation of alpha-D-galactose expression and reactive morphological changes in microglia during FMCM. These results suggest that disruption of the CNS milieu by entry of plasma constituents, or circulating malaria parasites in the absence of an immune response, by themselves are insufficient to induce the reactive microglial changes that are characteristic of FMCM. In addition, dexamethasone-sensitive event(s), presumably associated with immune system activation, occurring within the first few days of malaria infection are essential for the development of reactive microglia and subsequent fatal neurological complications.
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Affiliation(s)
- I M Medana
- Departments of Pathology and Anatomy and Histology, Institute for Biomedical Research, University of Sydney, Sydney, New South Wales, Australia
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Cardona AE, Restrepo BI, Jaramillo JM, Teale JM. Development of an Animal Model for Neurocysticercosis: Immune Response in the Central Nervous System Is Characterized by a Predominance of γδ T Cells. THE JOURNAL OF IMMUNOLOGY 1999. [DOI: 10.4049/jimmunol.162.2.995] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Abstract
Neurocysticercosis is the most common parasitic disease of the central nervous system worldwide. It is caused by the metacestode form of the helminth Taenia solium. Study of the immune response in the human brain has been limited by the chronic progression of the disease, the influence of corticosteroid treatment, and the scarcity of patients who undergo surgical intervention. To better understand the immune response and associated pathology in neurocysticercosis, a mouse model was developed by intracranial infection of BALB/c mice with Mesocestoides corti, a cestode organism related to T. solium. The immune response reveals the presence of abundant inflammatory infiltrates appearing as early as 2 days postinfection in extraparenchymal regions. In contrast, infiltration of immune cells into parenchymal tissue is significantly delayed. There is a natural progression of innate (neutrophils and macrophages), early induced (NK cells and γδ T cells), and adaptive immune responses (αβ T cells and B cells) in infected mice. γδ T cells are the predominant T cell population. A cell-mediated Th1 pathway of cytokine expression is evident in contrast to the previously described Th2 phenotype induced in the periphery.
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Affiliation(s)
- Astrid E. Cardona
- *Department of Microbiology, University of Texas Health Science Center, San Antonio, TX 78284; and
| | - Blanca I. Restrepo
- *Department of Microbiology, University of Texas Health Science Center, San Antonio, TX 78284; and
- †Corporación para Investigaciones Biológicas, Medellín, Colombia
| | - Juan M. Jaramillo
- *Department of Microbiology, University of Texas Health Science Center, San Antonio, TX 78284; and
- †Corporación para Investigaciones Biológicas, Medellín, Colombia
| | - Judy M. Teale
- *Department of Microbiology, University of Texas Health Science Center, San Antonio, TX 78284; and
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