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Kioko M, Mwangi S, Pance A, Ochola-Oyier LI, Kariuki S, Newton C, Bejon P, Rayner JC, Abdi AI. The mRNA content of plasma extracellular vesicles provides a window into molecular processes in the brain during cerebral malaria. SCIENCE ADVANCES 2024; 10:eadl2256. [PMID: 39151016 PMCID: PMC11328904 DOI: 10.1126/sciadv.adl2256] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Accepted: 07/10/2024] [Indexed: 08/18/2024]
Abstract
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.
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Affiliation(s)
- Mwikali Kioko
- Bioscience Department, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
- Open University, Milton Keynes, UK
| | - Shaban Mwangi
- Bioscience Department, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Alena Pance
- Pathogens and Microbes Programme, Wellcome Sanger Institute, Cambridge, UK
- School of Life and Medical Science, University of Hertfordshire, Hatfield, UK
| | - Lynette Isabella Ochola-Oyier
- Bioscience Department, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Symon Kariuki
- Bioscience Department, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
- Department of Psychiatry, University of Oxford, Oxford, UK
| | - Charles Newton
- Bioscience Department, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
- Department of Psychiatry, University of Oxford, Oxford, UK
| | - Philip Bejon
- Bioscience Department, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Julian C Rayner
- Cambridge Institute of Medical Research, University of Cambridge, Cambridge, UK
| | - Abdirahman I Abdi
- Bioscience Department, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
- Pwani University Biosciences Research Centre, Pwani University, Kilifi, Kenya
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2
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Bezzina AD, Spiteri Bailey J, Bertuello I. Type II Acute Macular Neuroretinopathy Secondary to Malaria. Case Rep Ophthalmol Med 2024; 2024:1577127. [PMID: 38938742 PMCID: PMC11208812 DOI: 10.1155/2024/1577127] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2024] [Revised: 05/09/2024] [Accepted: 05/11/2024] [Indexed: 06/29/2024] Open
Abstract
To the best of our knowledge, we present the first case of type II acute macular neuroretinopathy (AMN) exhibiting in a patient suffering from malarial retinopathy concomitant with cerebral malaria acquired after travelling to West Africa without taking the necessary antimalarial prophylaxis. The patient complained of bilateral blurring of vision after being removed off sedation whilst at the intensive care unit. Subsequent examination revealed bilateral retinal haemorrhages, cotton-wool spots, and foveal pigmentary changes in keeping malarial retinopathy. Macular optical coherence tomography (OCT) revealed patchy hyperreflective changes at the level of the outer plexiform and outer nuclear layers (ONL) in keeping with the areas of deep capillary plexus flow void noted on OCT-angiography (OCT-A). This case report sheds more light on the extent of neurosensory retinal ischaemia in malarial retinopathy and showcases a new imaging biomarker which may be utilized in assessing and quantifying the functional deficit created by this disease.
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Affiliation(s)
| | | | - Isaac Bertuello
- Ophthalmology DepartmentMater Dei General Teaching Hospital, Msida, Malta
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3
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Sharma I, Kataria P, Das J. Cerebral malaria pathogenesis: Dissecting the role of CD4 + and CD8 + T-cells as major effectors in disease pathology. Int Rev Immunol 2024; 43:309-325. [PMID: 38618863 DOI: 10.1080/08830185.2024.2336539] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2023] [Revised: 03/22/2024] [Accepted: 03/24/2024] [Indexed: 04/16/2024]
Abstract
Cerebral malaria (CM) is a severe complication of Plasmodium falciparum (P. falciparum) infection, with complex pathogenesis involving multiple factors, including the host's immunological response. T lymphocytes, specifically CD4+ T helper cells and CD8+ cytotoxic T cells, are crucial in controlling parasite growth and activating cells for parasite clearance via cytokine secretion. Contrary to this, reports also suggest the pathogenic nature of T lymphocytes as they are often involved in disease progression and severity. CD8+ cytotoxic T cells migrate to the host's brain vasculature, disrupting the blood-brain barrier and causing neurological manifestations. CD4+ T helper cells on the other hand play a variety of functions as they differentiate into different subtypes which may function as pro-inflammatory or anti-inflammatory. The excessive pro-inflammatory response in CM can lead to multi-organ failure, necessitating a check mechanism to maintain immune homeostasis. This is achieved by regulatory T cells and their characteristic cytokines, which counterbalance the pro-inflammatory immune response. Maintaining a critical balance between pro and anti-inflammatory responses is crucial for determining disease outcomes in CM. A slight change in this balance may contribute to a disease severity owing to an extreme inflammatory response or unrestricted parasite growth, a potential target for designing immunotherapeutic treatment approaches. The review briefly discusses the pathogenesis of CM and various mechanisms responsible for the disruption of the blood-brain barrier. It also highlights the role of different T cell subsets during infection and emphasizes the importance of balance between pro and anti-inflammatory T cells that ultimately decides the outcome of the disease.
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Affiliation(s)
- Indu Sharma
- Academy of Scientific and Innovative Research (AcSIR), Noida, India
- Division of Immunology, National Institute of Malaria Research, Dwarka, New Delhi, India
| | - Poonam Kataria
- Academy of Scientific and Innovative Research (AcSIR), Noida, India
- Division of Immunology, National Institute of Malaria Research, Dwarka, New Delhi, India
| | - Jyoti Das
- Academy of Scientific and Innovative Research (AcSIR), Noida, India
- Division of Immunology, National Institute of Malaria Research, Dwarka, New Delhi, India
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4
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Beare NAV. Cerebral malaria-using the retina to study the brain. Eye (Lond) 2023; 37:2379-2384. [PMID: 36788363 PMCID: PMC10397347 DOI: 10.1038/s41433-023-02432-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Revised: 01/14/2023] [Accepted: 01/30/2023] [Indexed: 02/16/2023] Open
Abstract
Cerebral malaria (CM) remains a common cause of death of children in Africa with annual mortality of 400 000. Malarial retinopathy is a unique set of fundus signs which has diagnostic and prognostic value in CM. Assessment of malarial retinopathy is now widely utilised in clinical care, and routinely incorporated into clinical studies to refine entry criteria. As a visible part of the central nervous system, the retina provides insights into the pathophysiology of this infectious small-vessel vasculitis with adherent parasitised red blood cells. Fluorescein angiography and optical coherence tomography (OCT) have shown that patchy capillary non-perfusion is common and causes ischaemic changes in the retina in CM. It is likely this is mirrored in the brain and may cause global neurological impairments evident on developmental follow up. Three types of blood-retina barrier breakdown are evident: large focal, punctate, and vessel leak. Punctate and large focal leak (haemorrhage in formation) are associated with severe brain swelling and fatal outcome. Vessel leak and capillary non-perfusion are associated with moderate brain swelling and neurological sequelae. These findings imply that death and neurological sequelae have separate mechanisms and are not a continuum of severity. Each haemorrhage causes a temporary uncontrolled outflow of fluid into the tissue. The rapid accumulation of haemorrhages, as evidenced by multiple focal leaks, is a proposed mechanism of severe brain swelling, and death. Current studies aim to use optic nerve head OCT to identify patients with severe brain swelling, and macula OCT to identify those at risk of neurological sequelae.
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Affiliation(s)
- Nicholas A V Beare
- Department of Eye and Vision Science, University of Liverpool, Liverpool, L7 8TX, UK.
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5
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Wilson KJ, Dhalla A, Meng Y, Tu Z, Zheng Y, Mhango P, Seydel KB, Beare NAV. Retinal imaging technologies in cerebral malaria: a systematic review. Malar J 2023; 22:139. [PMID: 37101295 PMCID: PMC10131356 DOI: 10.1186/s12936-023-04566-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Accepted: 04/20/2023] [Indexed: 04/28/2023] Open
Abstract
BACKGROUND Cerebral malaria (CM) continues to present a major health challenge, particularly in sub-Saharan Africa. CM is associated with a characteristic malarial retinopathy (MR) with diagnostic and prognostic significance. Advances in retinal imaging have allowed researchers to better characterize the changes seen in MR and to make inferences about the pathophysiology of the disease. The study aimed to explore the role of retinal imaging in diagnosis and prognostication in CM; establish insights into pathophysiology of CM from retinal imaging; establish future research directions. METHODS The literature was systematically reviewed using the African Index Medicus, MEDLINE, Scopus and Web of Science databases. A total of 35 full texts were included in the final analysis. The descriptive nature of the included studies and heterogeneity precluded meta-analysis. RESULTS Available research clearly shows retinal imaging is useful both as a clinical tool for the assessment of CM and as a scientific instrument to aid the understanding of the condition. Modalities which can be performed at the bedside, such as fundus photography and optical coherence tomography, are best positioned to take advantage of artificial intelligence-assisted image analysis, unlocking the clinical potential of retinal imaging for real-time diagnosis in low-resource environments where extensively trained clinicians may be few in number, and for guiding adjunctive therapies as they develop. CONCLUSIONS Further research into retinal imaging technologies in CM is justified. In particular, co-ordinated interdisciplinary work shows promise in unpicking the pathophysiology of a complex disease.
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Affiliation(s)
- Kyle J Wilson
- Department of Eye & Vision Sciences, University of Liverpool, Liverpool, UK.
- Malawi-Liverpool-Wellcome Trust, Blantyre, Malawi.
| | - Amit Dhalla
- Department of Ophthalmology, Sheffield Teaching Hospitals, Sheffield, UK
| | - Yanda Meng
- Department of Eye & Vision Sciences, University of Liverpool, Liverpool, UK
| | - Zhanhan Tu
- School of Psychology and Vision Sciences, College of Life Science, The University of Leicester Ulverscroft Eye Unit, Robert Kilpatrick Clinical Sciences Building, Leicester Royal Infirmary, Leicester, UK
| | - Yalin Zheng
- Department of Eye & Vision Sciences, University of Liverpool, Liverpool, UK
- St. Paul's Eye Unit, Royal Liverpool University Hospitals, Liverpool, UK
- Liverpool Centre for Cardiovascular Science, University of Liverpool and Liverpool Heart and Chest Hospital, Liverpool, UK
| | - Priscilla Mhango
- Department of Ophthalmology, Kamuzu University of Health Sciences, Blantyre, Malawi
| | - Karl B Seydel
- College of Osteopathic Medicine, Michigan State University, East Lansing, MI, USA
- Blantyre Malaria Project, Kamuzu University of Health Sciences, Blantyre, Malawi
| | - Nicholas A V Beare
- Department of Eye & Vision Sciences, University of Liverpool, Liverpool, UK.
- St. Paul's Eye Unit, Royal Liverpool University Hospitals, Liverpool, UK.
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6
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Kurup AR, Wigdahl J, Benson J, Martínez-Ramón M, Solíz P, Joshi V. Automated malarial retinopathy detection using transfer learning and multi-camera retinal images. Biocybern Biomed Eng 2023; 43:109-123. [PMID: 36685736 PMCID: PMC9851283 DOI: 10.1016/j.bbe.2022.12.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Cerebral malaria (CM) is a fatal syndrome found commonly in children less than 5 years old in Sub-saharan Africa and Asia. The retinal signs associated with CM are known as malarial retinopathy (MR), and they include highly specific retinal lesions such as whitening and hemorrhages. Detecting these lesions allows the detection of CM with high specificity. Up to 23% of CM, patients are over-diagnosed due to the presence of clinical symptoms also related to pneumonia, meningitis, or others. Therefore, patients go untreated for these pathologies, resulting in death or neurological disability. It is essential to have a low-cost and high-specificity diagnostic technique for CM detection, for which We developed a method based on transfer learning (TL). Models pre-trained with TL select the good quality retinal images, which are fed into another TL model to detect CM. This approach shows a 96% specificity with low-cost retinal cameras.
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Affiliation(s)
| | - Jeff Wigdahl
- VisionQuest Biomedical Inc., Albuquerque, NM, USA
| | | | | | - Peter Solíz
- VisionQuest Biomedical Inc., Albuquerque, NM, USA
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Abstract
Severe malaria is a medical emergency. It is a major cause of preventable childhood death in tropical countries. Severe malaria justifies considerable global investment in malaria control and elimination yet, increasingly, international agencies, funders and policy makers are unfamiliar with it, and so it is overlooked. In sub-Saharan Africa, severe malaria is overdiagnosed in clinical practice. Approximately one third of children diagnosed with severe malaria have another condition, usually sepsis, as the cause of their severe illness. But these children have a high mortality, contributing substantially to the number of deaths attributed to 'severe malaria'. Simple well-established tests, such as examination of the thin blood smear and the full blood count, improve the specificity of diagnosis and provide prognostic information in severe malaria. They should be performed more widely. Early administration of artesunate and broad-spectrum antibiotics to all children with suspected severe malaria would reduce global malaria mortality.
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Affiliation(s)
- Nicholas J White
- Mahidol Oxford Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK.
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8
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MacCormick IJC, Lewallen S, Beare N, Harding SP. Measuring the Impact of Malaria on the Living Human Retina. Methods Mol Biol 2022; 2470:731-748. [PMID: 35881386 DOI: 10.1007/978-1-0716-2189-9_54] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Retinal examination and imaging are relatively simple methods for studying the dynamic impact of cerebral malaria on the microcirculation of the central nervous system. Retina and brain are affected similarly by Plasmodium falciparum. Unlike the brain, the human retina can be directly observed using commercially available clinical instruments in the setting of a critical care unit, and this can be done repeatedly and non-invasively. Additional information about blood-tissue barriers can be gained from fluorescein angiography. Non-ophthalmologist clinician scientists are usually unfamiliar with ophthalmoscopy and retinal imaging, and some readers may feel that these techniques are beyond them. This chapter aims to quell these fears by providing a step-by-step description of how to examine and photograph the human retina in children with cerebral malaria.
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Affiliation(s)
- Ian James Callum MacCormick
- Centre for Inflammation Research, University of Edinburgh, The Queen's Medical Research Institute, Edinburgh, UK.
| | - Susan Lewallen
- Kilimanjaro Centre for Community Ophthalmology, Division of Ophthalmology, University of Cape Town, Observatory, South Africa
| | - Nicholas Beare
- Department of Eye and Vision Science, University of Liverpool, Liverpool, UK
- St. Paul's Eye Unit, Liverpool University Hospitals NHS Foundation Trust, Liverpool, L7 8XP, members of Liverpool Health Partners, Liverpool, UK
| | - Simon Peter Harding
- Department of Eye and Vision Science, University of Liverpool, Liverpool, UK
- St. Paul's Eye Unit, Liverpool University Hospitals NHS Foundation Trust, Liverpool, L7 8XP, members of Liverpool Health Partners, Liverpool, UK
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9
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White VA, Barrera V, MacCormick IJC. Ocular Pathology of Cerebral Malaria. Methods Mol Biol 2022; 2470:749-763. [PMID: 35881387 DOI: 10.1007/978-1-0716-2189-9_55] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Investigation of post-mortem eyes from children with malarial retinopathy has helped to explain the retinal pathology of cerebral malaria, and also demonstrated histological associations between evolving retinal pathogenesis-visible clinically-and similar cerebral features which can only be examined at autopsy. The pathology of malarial retinopathy has been well-described and correlates with brain pathology. Some clinical and pathological features are associated with outcome. This chapter describes the materials and methods needed to study the pathological features of malarial retinopathy. Some are common to histopathology in general, but accurate spatial correlation between retinal features observed in life and their associated pathology in post-mortem specimens requires special techniques.
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Affiliation(s)
- Valerie Ann White
- International Agency for Research on Cancer, WHO Classification of Tumours Group, Lyon Cedex, France
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10
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Faber H, Berens P, Rohrbach JM. [Ocular changes as a diagnostic tool for malaria]. Ophthalmologe 2021; 119:693-698. [PMID: 34940911 DOI: 10.1007/s00347-021-01554-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Revised: 10/29/2021] [Accepted: 11/26/2021] [Indexed: 11/28/2022]
Abstract
BACKGROUND According to the WHO Malaria Report 2019 a total of 229 million people fall ill with malaria each year and two thirds of deaths involve children under 5 years of age. AIM To review the fundus changes in the context of malaria and the importance of ophthalmoscopy in the diagnosis. MATERIAL AND METHODS Summary of changes in cerebral malaria visible on fundus examination, possible underlying pathomechanisms and the value of ophthalmoscopy in practice. RESULTS Retinal findings in malaria include white or gray staining of the retina (retinal whitening), color change of retinal vessels (orange or white staining), hemorrhages often with a white center, such as Roth's spot and papilledema. DISCUSSION The retinal changes in malaria are specific and may help to differentiate malaria from other causes of coma and fever. Smartphone-based fundus photography and artificial intelligence could support malaria diagnostics particularly in resource-poor regions.
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Affiliation(s)
- Hanna Faber
- Universitäts-Augenklinik Tübingen, Universitätsklinikum Tübingen, Tübingen, Deutschland. .,Department für Augenheilkunde, Universitätsklinikum Tübingen, Tübingen, Deutschland, Elfriede-Aulhorn-Str. 7, 72076.
| | - Philipp Berens
- Department für Augenheilkunde, Universitätsklinikum Tübingen, Tübingen, Deutschland, Elfriede-Aulhorn-Str. 7, 72076.,Tübingen AI Center, Tübingen, Deutschland
| | - Jens Martin Rohrbach
- Universitäts-Augenklinik Tübingen, Universitätsklinikum Tübingen, Tübingen, Deutschland
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11
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Andoh NE, Gyan BA. The Potential Roles of Glial Cells in the Neuropathogenesis of Cerebral Malaria. Front Cell Infect Microbiol 2021; 11:741370. [PMID: 34692564 PMCID: PMC8529055 DOI: 10.3389/fcimb.2021.741370] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Accepted: 09/17/2021] [Indexed: 01/02/2023] Open
Abstract
Cerebral malaria (CM) is a severe neurological complication of malaria caused by the Plasmodium falciparum parasite. It is one of the leading causes of death in children under 5 years of age in Sub-Saharan Africa. CM is associated with blood-brain barrier disruption and long-term neurological sequelae in survivors of CM. Despite the vast amount of research on cerebral malaria, the cause of neurological sequelae observed in CM patients is poorly understood. In this article, the potential roles of glial cells, astrocytes, and microglia, in cerebral malaria pathogenesis are reviewed. The possible mechanisms by which glial cells contribute to neurological damage in CM patients are also examined.
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Affiliation(s)
- Nana Efua Andoh
- Noguchi Memorial Institute for Medical Research, Department of Parasitology, University of Ghana, Accra, Ghana
| | - Ben Adu Gyan
- Noguchi Memorial Institute for Medical Research, Department of Immunology, University of Ghana, Accra, Ghana
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12
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Tu Z, Gormley J, Sheth V, Seydel KB, Taylor T, Beare N, Barrera V, Proudlock FA, Manda C, Harding S, Gottlob I. Cerebral malaria: insight into pathology from optical coherence tomography. Sci Rep 2021; 11:15722. [PMID: 34344903 PMCID: PMC8333417 DOI: 10.1038/s41598-021-94495-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2021] [Accepted: 07/08/2021] [Indexed: 01/25/2023] Open
Abstract
We aimed to investigate structural retinal changes in malarial retinopathy (MR) using hand-held optical coherence tomography (HH-OCT) to assess its diagnostic potential. Children with MR (n = 43) underwent ophthalmoscopy, fluorescein angiography and HH-OCT during admission, 1-month (n = 31) and 1-year (n = 8) post-discharge. Controls were comatose patients without malaria (n = 6) and age/sex-matched healthy children (n = 43). OCT changes and retinal layer thicknesses were compared. On HH-OCT, hyper-reflective areas (HRAs) were seen in the inner retina of 81% of MR patients, corresponding to ischaemic retinal whitening on fundus photography. Cotton wool spots were present in 37% and abnormal hyper-reflective dots, co-localized to capillary plexus, in 93%. Hyper-reflective vessel walls were present in 84%, and intra-retinal cysts in 9%. Vascular changes and cysts resolved within 48 h. HRAs developed into retinal thinning at 1 month (p = 0.027) which was more pronounced after 1 year (p = 0.009). Ischaemic retinal whitening is located within inner retinal layers, distinguishing it from cotton wool spots. Vascular hyper-reflectivity may represent the sequestration of parasitized erythrocytes in vessels, a key CM feature. The mechanisms of post-ischemic retinal atrophy and cerebral atrophy with cognitive impairment may be similar in CM survivors. HH-OCT has the potential for monitoring patients, treatment response and predicting neurological deficits.
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Affiliation(s)
- Zhanhan Tu
- Department of Neuroscience, Psychology and Behaviour, Ulverscroft Eye Unit, University of Leicester, Robert Kilpatrick Clinical Sciences Building, Leicester Royal Infirmary, Leicester, LE2 7LX, UK
| | - Jack Gormley
- Department of Eye and Vision Science, Institute of Ageing and Chronic Disease, University of Liverpool, Member of Liverpool Health Partners, Liverpool, UK
| | - Viral Sheth
- Department of Neuroscience, Psychology and Behaviour, Ulverscroft Eye Unit, University of Leicester, Robert Kilpatrick Clinical Sciences Building, Leicester Royal Infirmary, Leicester, LE2 7LX, UK
| | - Karl B Seydel
- Blantyre Malaria Project, University of Malawi College of Medicine, Blantyre, Malawi
- Department of Osteopathic Medical Specialties, College of Osteopathic Medicine, Michigan State University, East Lansing, MI, USA
| | - Terrie Taylor
- Blantyre Malaria Project, University of Malawi College of Medicine, Blantyre, Malawi
- Department of Osteopathic Medical Specialties, College of Osteopathic Medicine, Michigan State University, East Lansing, MI, USA
| | - Nicholas Beare
- Department of Eye and Vision Science, Institute of Ageing and Chronic Disease, University of Liverpool, Member of Liverpool Health Partners, Liverpool, UK
| | - Valentina Barrera
- Department of Eye and Vision Science, Institute of Ageing and Chronic Disease, University of Liverpool, Member of Liverpool Health Partners, Liverpool, UK
| | - Frank A Proudlock
- Department of Neuroscience, Psychology and Behaviour, Ulverscroft Eye Unit, University of Leicester, Robert Kilpatrick Clinical Sciences Building, Leicester Royal Infirmary, Leicester, LE2 7LX, UK
| | - Chatonda Manda
- University of Malawi College of Medicine, Blantyre, Malawi
| | - Simon Harding
- Department of Eye and Vision Science, Institute of Ageing and Chronic Disease, University of Liverpool, Member of Liverpool Health Partners, Liverpool, UK
| | - Irene Gottlob
- Department of Neuroscience, Psychology and Behaviour, Ulverscroft Eye Unit, University of Leicester, Robert Kilpatrick Clinical Sciences Building, Leicester Royal Infirmary, Leicester, LE2 7LX, UK.
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13
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Parasite histones are toxic to brain endothelium and link blood barrier breakdown and thrombosis in cerebral malaria. Blood Adv 2021; 4:2851-2864. [PMID: 32579667 DOI: 10.1182/bloodadvances.2019001258] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Accepted: 05/17/2020] [Indexed: 12/16/2022] Open
Abstract
Microvascular thrombosis and blood-brain barrier (BBB) breakdown are key components of cerebral malaria (CM) pathogenesis in African children and are implicated in fatal brain swelling. How Plasmodium falciparum infection causes this endothelial disruption and why this occurs, particularly in the brain, is not fully understood. In this study, we have demonstrated that circulating extracellular histones, equally of host and parasite origin, are significantly elevated in CM patients. Higher histone levels are associated with brain swelling on magnetic resonance imaging. On postmortem brain sections of CM patients, we found that histones are colocalized with P falciparum-infected erythrocytes sequestered inside small blood vessels, suggesting that histones might be expelled locally during parasite schizont rupture. Histone staining on the luminal vascular surface colocalized with thrombosis and leakage, indicating a possible link between endothelial surface accumulation of histones and coagulation activation and BBB breakdown. Supporting this, patient sera or purified P falciparum histones caused disruption of barrier function and were toxic to cultured human brain endothelial cells, which were abrogated with antihistone antibody and nonanticoagulant heparin. Overall, our data support a role for histones of parasite and host origin in thrombosis, BBB breakdown, and brain swelling in CM, processes implicated in the causal pathway to death. Neutralizing histones with agents such as nonanticoagulant heparin warrant exploration to prevent brain swelling in the development or progression of CM and thereby to improve outcomes.
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14
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Bioengineered 3D Microvessels for Investigating Plasmodium falciparum Pathogenesis. Trends Parasitol 2021; 37:401-413. [PMID: 33485788 DOI: 10.1016/j.pt.2020.12.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Revised: 12/15/2020] [Accepted: 12/25/2020] [Indexed: 12/18/2022]
Abstract
Plasmodium falciparum pathogenesis is complex and intimately connected to vascular physiology. This is exemplified by cerebral malaria (CM), a neurovascular complication that accounts for most of the malaria deaths worldwide. P. falciparum sequestration in the brain microvasculature is a hallmark of CM and is not replicated in animal models. Numerous aspects of the disease are challenging to fully understand from clinical studies, such as parasite binding tropism or causal pathways in blood-brain barrier breakdown. Recent bioengineering approaches allow for the generation of 3D microvessels and organ-specific vasculature that provide precise control of vessel architecture and flow dynamics, and hold great promise for malaria research. Here, we discuss recent and future applications of bioengineered microvessels in malaria pathogenesis research.
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Joste V, Guillochon E, Fraering J, Vianou B, Watier L, Jafari-Guemouri S, Cot M, Houzé S, Aubouy A, Faucher JF, Argy N, Bertin GI. PfEMP1 A-Type ICAM-1-Binding Domains Are Not Associated with Cerebral Malaria in Beninese Children. mBio 2020; 11:e02103-20. [PMID: 33203751 PMCID: PMC7683394 DOI: 10.1128/mbio.02103-20] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Accepted: 10/12/2020] [Indexed: 11/20/2022] Open
Abstract
PfEMP1 is the major antigen involved in Plasmodium falciparum-infected erythrocyte sequestration in cerebrovascular endothelium. While some PfEMP1 domains have been associated with clinical phenotypes of malaria, formal associations between the expression of a specific domain and the adhesion properties of clinical isolates are limited. In this context, 73 cerebral malaria (CM) and 98 uncomplicated malaria (UM) Beninese children were recruited. We attempted to correlate the cytoadherence phenotype of Plasmodium falciparum isolates with the clinical presentation and the expression of specific PfEMP1 domains. Cytoadherence level on Hbec-5i and CHO-ICAM-1 cell lines and var genes expression were measured. We also investigated the prevalence of the ICAM-1-binding amino acid motif and dual receptor-binding domains, described as a potential determinant of cerebral malaria pathophysiology. We finally evaluated IgG levels against PfEMP1 recombinant domains (CIDRα1.4, DBLβ3, and CIDRα1.4-DBLβ3). CM isolates displayed higher cytoadherence levels on both cell lines, and we found a correlation between CIDRα1.4-DBLβ1/3 domain expression and CHO-ICAM-1 cytoadherence level. Endothelial protein C receptor (EPCR)-binding domains were overexpressed in CM isolates compared to UM whereas no difference was found in ICAM-1-binding DBLβ1/3 domain expression. Surprisingly, both CM and UM isolates expressed ICAM-1-binding motif and dual receptor-binding domains. There was no difference in IgG response against DBLβ3 between CM and UM isolates expressing ICAM-1-binding DBLβ1/3 domain. It raises questions about the role of this motif in CM pathophysiology, and further studies are needed, especially on the role of DBLβ1/3 without the ICAM-1-binding motif.IMPORTANCE Cerebral malaria pathophysiology remains unknown despite extensive research. PfEMP1 proteins have been identified as the main Plasmodium antigen involved in cerebrovascular endothelium sequestration, but it is unclear which var gene domain is involved in Plasmodium cytoadhesion. EPCR binding is a major determinant of cerebral malaria whereas the ICAM-1-binding role is still questioned. Our study confirmed the EPCR-binding role in CM pathophysiology with a major overexpression of EPCR-binding domains in CM isolates. In contrast, ICAM-1-binding involvement appears less obvious with A-type ICAM-1-binding and dual receptor-binding domain expression in both CM and UM isolates. We did not find any variations in ICAM-1-binding motif sequences in CM compared to UM isolates. UM and CM patients infected with isolates expressing the ICAM-1-binding motif displayed similar IgG levels against DBLβ3 recombinant protein. Our study raises interrogations about the role of these domains in CM physiopathology and questions their use in vaccine strategies against cerebral malaria.
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Affiliation(s)
- V Joste
- Université de Paris, MERIT, IRD, Paris, France
| | | | - J Fraering
- Université de Paris, MERIT, IRD, Paris, France
| | - B Vianou
- Université de Paris, MERIT, IRD, Paris, France
- Institut de Recherche Clinique du Bénin (IRCB), Cotonou, Bénin
| | - L Watier
- Department of Biostatistics, Biomathematics, Pharmacoepidemiology and Infectious Diseases (B2PHI), Inserm, UVSQ, Institut Pasteur, Université Paris-Saclay, Paris, France
| | | | - M Cot
- Université de Paris, MERIT, IRD, Paris, France
| | - S Houzé
- Université de Paris, MERIT, IRD, Paris, France
- Parasitology Laboratory, Bichat-Claude Bernard hospital, Paris, France
- Malaria National Reference Center, Bichat-Claude Bernard hospital, Paris, France
| | - A Aubouy
- Université de Toulouse, PHARMADEV, IRD, UPS, Toulouse, France
| | - J F Faucher
- Université de Limoges, NET, INSERM, Limoges, France
| | - N Argy
- Université de Paris, MERIT, IRD, Paris, France
- Parasitology Laboratory, Bichat-Claude Bernard hospital, Paris, France
- Malaria National Reference Center, Bichat-Claude Bernard hospital, Paris, France
| | - G I Bertin
- Université de Paris, MERIT, IRD, Paris, France
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16
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MacCormick IJC, Barrera V, Beare NAV, Czanner G, Potchen M, Kampondeni S, Heyderman RS, Craig AG, Molyneux ME, Mallewa M, White VA, Milner D, Hiscott P, Taylor TE, Seydel KB, Harding SP. How Does Blood-Retinal Barrier Breakdown Relate to Death and Disability in Pediatric Cerebral Malaria? J Infect Dis 2020; 225:1070-1080. [PMID: 32845969 PMCID: PMC8922008 DOI: 10.1093/infdis/jiaa541] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Accepted: 08/24/2020] [Indexed: 11/25/2022] Open
Abstract
Background In cerebral malaria, the retina can be used to understand disease pathogenesis. The mechanisms linking sequestration, brain swelling, and death remain poorly understood. We hypothesized that retinal vascular leakage would be associated with brain swelling. Methods We used retinal angiography to study blood-retinal barrier integrity. We analyzed retinal leakage, histopathology, brain magnatic resonance imaging (MRI), and associations with death and neurological disability in prospective cohorts of Malawian children with cerebral malaria. Results Three types of retinal leakage were seen: large focal leak (LFL), punctate leak (PL), and vessel leak. The LFL and PL were associated with death (odds ratio [OR] = 13.20, 95% confidence interval [CI] = 5.21–33.78 and OR = 8.58, 95% CI = 2.56–29.08, respectively) and brain swelling (P < .05). Vessel leak and macular nonperfusion were associated with neurological disability (OR = 3.71, 95% CI = 1.26–11.02 and OR = 9.06, 95% CI = 1.79–45.90). Large focal leak was observed as an evolving retinal hemorrhage. A core of fibrinogen and monocytes was found in 39 (93%) white-centered hemorrhages. Conclusions Blood-retina barrier breakdown occurs in 3 patterns in cerebral malaria. Associations between LFL, brain swelling, and death suggest that the rapid accumulation of cerebral hemorrhages, with accompanying fluid egress, may cause fatal brain swelling. Vessel leak, from barrier dysfunction, and nonperfusion were not associated with severe brain swelling but with neurological deficits, suggesting hypoxic injury in survivors.
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Affiliation(s)
- Ian J C MacCormick
- Department of Eye and Vision Science, Institute of Life Course and Medical Sciences, University of Liverpool, a member of Liverpool Health Partners, Liverpool, UK.,Malawi-Liverpool-Wellcome Trust Clinical Research Programme, Queen Elizabeth Central Hospital, Blantyre, Malawi.,Centre for Inflammation Research, University of Edinburgh, Edinburgh, UK
| | - Valentina Barrera
- Department of Eye and Vision Science, Institute of Life Course and Medical Sciences, University of Liverpool, a member of Liverpool Health Partners, Liverpool, UK.,NHS Blood and Transplant, Tissue and Eye Services R&D, Liverpool UK
| | - Nicholas A V Beare
- Department of Eye and Vision Science, Institute of Life Course and Medical Sciences, University of Liverpool, a member of Liverpool Health Partners, Liverpool, UK.,St. Paul's Eye Unit, Liverpool University Hospitals Foundation Trust, Liverpool, UK
| | - Gabriela Czanner
- Department of Eye and Vision Science, Institute of Life Course and Medical Sciences, University of Liverpool, a member of Liverpool Health Partners, Liverpool, UK.,Department of Applied Mathematics, Liverpool John Moores University, Liverpool, UK
| | - Michael Potchen
- Department of Imaging Sciences, University of Rochester Medical Center, Rochester, NY, USA
| | - Samuel Kampondeni
- Department of Imaging Sciences, University of Rochester Medical Center, Rochester, NY, USA.,Blantyre Malaria Project, University of Malawi College of Medicine, Blantyre, Malawi
| | - Robert S Heyderman
- Malawi-Liverpool-Wellcome Trust Clinical Research Programme, Queen Elizabeth Central Hospital, Blantyre, Malawi.,Division of Infection & Immunity, University College London, London, UK
| | - Alister G Craig
- Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, UK
| | - Malcolm E Molyneux
- Malawi-Liverpool-Wellcome Trust Clinical Research Programme, Queen Elizabeth Central Hospital, Blantyre, Malawi.,Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, UK
| | - Macpherson Mallewa
- Department of Paediatrics and Child Health, Queen Elizabeth Central Hospital, Blantyre, Malawi
| | - Valerie A White
- Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Dan Milner
- American Society for Clinical Pathology, Chicago, IL, USA
| | - Paul Hiscott
- Department of Eye and Vision Science, Institute of Life Course and Medical Sciences, University of Liverpool, a member of Liverpool Health Partners, Liverpool, UK
| | - Terrie E Taylor
- Blantyre Malaria Project, University of Malawi College of Medicine, Blantyre, Malawi.,Department of Osteopathic Medical Specialties, College of Osteopathic Medicine, Michigan State University, East Lansing, USA
| | - Karl B Seydel
- Blantyre Malaria Project, University of Malawi College of Medicine, Blantyre, Malawi.,Department of Osteopathic Medical Specialties, College of Osteopathic Medicine, Michigan State University, East Lansing, USA
| | - Simon P Harding
- Department of Eye and Vision Science, Institute of Life Course and Medical Sciences, University of Liverpool, a member of Liverpool Health Partners, Liverpool, UK.,St. Paul's Eye Unit, Liverpool University Hospitals Foundation Trust, Liverpool, UK
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17
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Abstract
PURPOSE OF REVIEW Malaria threatens the lives of over 200 million individuals with the disease each year. Plasmodium falciparum is the predominant cause of severe malaria which may be lethal and result in neurocognitive sequelae despite appropriate treatment. We review recent advances regarding the pathophysiology of severe malaria and treatment recommendations for severe disease in the United States. RECENT FINDINGS Infected red blood cell (iRBC) sequestration in microvascular beds is a critical factor in the development of severe malaria syndromes. Interactions between iRBC variant adhesive peptides and the endothelial protein C receptor (EPCR) result in perturbations of coagulation and cytopreservation pathways. Alterations in the protein C/EPCR axis are implicated in cerebral malaria, respiratory distress, and anemia. Brain MRIs reveal the posterior reversible encephalopathy syndrome in cerebral malaria patients. Transcriptomic analysis reveals commonalities in disease pathogenesis in children and adults despite differences in clinical presentation. US guidelines for severe malaria treatment currently recommend intravenous artesunate including in pregnant women and children. SUMMARY Despite advances in our understanding of malarial pathogenesis much remains unknown. Antimalarial agents eradicate parasites but no treatments are available to prevent or ameliorate severe malaria or prevent disease sequelae. Further study is needed to develop effective adjunctive therapies.
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18
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Arakawa C, Gunnarsson C, Howard C, Bernabeu M, Phong K, Yang E, DeForest CA, Smith JD, Zheng Y. Biophysical and biomolecular interactions of malaria-infected erythrocytes in engineered human capillaries. SCIENCE ADVANCES 2020; 6:eaay7243. [PMID: 32010773 PMCID: PMC6968943 DOI: 10.1126/sciadv.aay7243] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2019] [Accepted: 11/20/2019] [Indexed: 05/14/2023]
Abstract
Microcirculatory obstruction is a hallmark of severe malaria, but mechanisms of parasite sequestration are only partially understood. Here, we developed a robust three-dimensional microvessel model that mimics the arteriole-capillary-venule (ACV) transition consisting of a narrow 5- to 10-μm-diameter capillary region flanked by arteriole- or venule-sized vessels. Using this platform, we investigated red blood cell (RBC) transit at the single cell and at physiological hematocrits. We showed normal RBCs deformed via in vivo-like stretching and tumbling with negligible interactions with the vessel wall. By comparison, Plasmodium falciparum-infected RBCs exhibited virtually no deformation and rapidly accumulated in the capillary-sized region. Comparison of wild-type parasites to those lacking either cytoadhesion ligands or membrane-stiffening knobs showed highly distinctive spatial and temporal kinetics of accumulation, linked to velocity transition in ACVs. Our findings shed light on mechanisms of microcirculatory obstruction in malaria and establish a new platform to study hematologic and microvascular diseases.
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Affiliation(s)
- Christopher Arakawa
- Department of Bioengineering, University of Washington, Seattle, WA 98105, USA
| | - Celina Gunnarsson
- Department of Bioengineering, University of Washington, Seattle, WA 98105, USA
| | - Caitlin Howard
- Department of Bioengineering, University of Washington, Seattle, WA 98105, USA
| | - Maria Bernabeu
- Seattle Children’s Research Institute, Seattle, WA 98101, USA
| | - Kiet Phong
- Department of Bioengineering, University of Washington, Seattle, WA 98105, USA
| | - Eric Yang
- Department of Bioengineering, University of Washington, Seattle, WA 98105, USA
| | - Cole A. DeForest
- Department of Bioengineering, University of Washington, Seattle, WA 98105, USA
- Department of Chemical Engineering, University of Washington, Seattle, WA 98195, USA
| | - Joseph D. Smith
- Seattle Children’s Research Institute, Seattle, WA 98101, USA
- Department of Global Health, University of Washington, Seattle, WA 98105, USA
| | - Ying Zheng
- Department of Bioengineering, University of Washington, Seattle, WA 98105, USA
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19
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Moxon CA, Gibbins MP, McGuinness D, Milner DA, Marti M. New Insights into Malaria Pathogenesis. ANNUAL REVIEW OF PATHOLOGY-MECHANISMS OF DISEASE 2019; 15:315-343. [PMID: 31648610 DOI: 10.1146/annurev-pathmechdis-012419-032640] [Citation(s) in RCA: 91] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Malaria remains a major public health threat in tropical and subtropical regions across the world. Even though less than 1% of malaria infections are fatal, this leads to about 430,000 deaths per year, predominantly in young children in sub-Saharan Africa. Therefore, it is imperative to understand why a subset of infected individuals develop severe syndromes and some of them die and what differentiates these cases from the majority that recovers. Here, we discuss progress made during the past decade in our understanding of malaria pathogenesis, focusing on the major human parasite Plasmodium falciparum.
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Affiliation(s)
- Christopher A Moxon
- Wellcome Centre for Integrative Parasitology, Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow G12 8TA, United Kingdom; ,
| | - Matthew P Gibbins
- Wellcome Centre for Integrative Parasitology, Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow G12 8TA, United Kingdom; ,
| | - Dagmara McGuinness
- Wellcome Centre for Integrative Parasitology, Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow G12 8TA, United Kingdom; ,
| | - Danny A Milner
- American Society for Clinical Pathology, Chicago, Illinois 60603, USA.,Department of Immunology and Infectious Disease, Harvard T.H. Chan School of Public Health, Boston, Massachusetts 02115, USA
| | - Matthias Marti
- Wellcome Centre for Integrative Parasitology, Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow G12 8TA, United Kingdom; , .,Department of Immunology and Infectious Disease, Harvard T.H. Chan School of Public Health, Boston, Massachusetts 02115, USA
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20
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Knackstedt SL, Georgiadou A, Apel F, Abu-Abed U, Moxon CA, Cunnington AJ, Raupach B, Cunningham D, Langhorne J, Krüger R, Barrera V, Harding SP, Berg A, Patel S, Otterdal K, Mordmüller B, Schwarzer E, Brinkmann V, Zychlinsky A, Amulic B. Neutrophil extracellular traps drive inflammatory pathogenesis in malaria. Sci Immunol 2019; 4:eaaw0336. [PMID: 31628160 PMCID: PMC6892640 DOI: 10.1126/sciimmunol.aaw0336] [Citation(s) in RCA: 94] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Revised: 06/04/2019] [Accepted: 09/17/2019] [Indexed: 12/13/2022]
Abstract
Neutrophils are essential innate immune cells that extrude chromatin in the form of neutrophil extracellular traps (NETs) when they die. This form of cell death has potent immunostimulatory activity. We show that heme-induced NETs are essential for malaria pathogenesis. Using patient samples and a mouse model, we define two mechanisms of NET-mediated inflammation of the vasculature: activation of emergency granulopoiesis via granulocyte colony-stimulating factor production and induction of the endothelial cytoadhesion receptor intercellular adhesion molecule-1. Soluble NET components facilitate parasite sequestration and mediate tissue destruction. We demonstrate that neutrophils have a key role in malaria immunopathology and propose inhibition of NETs as a treatment strategy in vascular infections.
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Affiliation(s)
- Sebastian Lorenz Knackstedt
- Max Planck Institute for Infection Biology, Department of Cellular Microbiology, Charitéplatz 1, 10117 Berlin, Germany
| | | | - Falko Apel
- Max Planck Institute for Infection Biology, Department of Cellular Microbiology, Charitéplatz 1, 10117 Berlin, Germany
| | - Ulrike Abu-Abed
- Max Planck Institute for Infection Biology, Microscopy Core Facility, Charitéplatz 1, 10117 Berlin, Germany
| | - Christopher A Moxon
- Wellcome Centre for Integrative Parasitology, Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, UK
- Institute of Infection and Global Health, University of Liverpool, 8 West Derby Street, Liverpool L69 7BE, UK
| | | | - Bärbel Raupach
- Max Planck Institute for Infection Biology, Department of Cellular Microbiology, Charitéplatz 1, 10117 Berlin, Germany
| | | | - Jean Langhorne
- Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Renate Krüger
- Charité-Universitätsmedizin Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Department of Pediatric Pneumology, Immunology and Intensive Care, Berlin, Germany
| | - Valentina Barrera
- Department of Eye and Vision Science, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, UK
| | - Simon P Harding
- Department of Eye and Vision Science, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, UK
| | - Aase Berg
- Stavanger University Hospital, Stavanger, Norway
| | - Sam Patel
- Maputo Central Hospital, Maputo, Mozambique
| | - Kari Otterdal
- Research Institute of Internal Medicine, Oslo University Hospital Rikshospitalet, Oslo, Norway
| | - Benjamin Mordmüller
- Centre de Recherches Médicales de Lambaréné (CERMEL), Lambaréné, Gabon
- Universität Tübingen, Institut für Tropenmedizin, Wilhelmstraße 27, 72074 Tübingen, Germany
| | - Evelin Schwarzer
- Department of Oncology, University of Turin, Via Santena 5 bis, 10126 Turin, Italy
| | - Volker Brinkmann
- Max Planck Institute for Infection Biology, Microscopy Core Facility, Charitéplatz 1, 10117 Berlin, Germany
| | - Arturo Zychlinsky
- Max Planck Institute for Infection Biology, Department of Cellular Microbiology, Charitéplatz 1, 10117 Berlin, Germany
| | - Borko Amulic
- Max Planck Institute for Infection Biology, Department of Cellular Microbiology, Charitéplatz 1, 10117 Berlin, Germany.
- University of Bristol, School of Cellular and Molecular Medicine, Bristol BS8 1TD, UK
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21
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Rosetting revisited: a critical look at the evidence for host erythrocyte receptors in Plasmodium falciparum rosetting. Parasitology 2019; 147:1-11. [PMID: 31455446 PMCID: PMC7050047 DOI: 10.1017/s0031182019001288] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Malaria remains a major cause of mortality in African children, with no adjunctive treatments currently available to ameliorate the severe clinical forms of the disease. Rosetting, the adhesion of infected erythrocytes (IEs) to uninfected erythrocytes, is a parasite phenotype strongly associated with severe malaria, and hence is a potential therapeutic target. However, the molecular mechanisms of rosetting are complex and involve multiple distinct receptor–ligand interactions, with some similarities to the diverse pathways involved in P. falciparum erythrocyte invasion. This review summarizes the current understanding of the molecular interactions that lead to rosette formation, with a particular focus on host uninfected erythrocyte receptors including the A and B blood group trisaccharides, complement receptor one, heparan sulphate, glycophorin A and glycophorin C. There is strong evidence supporting blood group A trisaccharides as rosetting receptors, but evidence for other molecules is incomplete and requires further study. It is likely that additional host erythrocyte rosetting receptors remain to be discovered. A rosette-disrupting low anti-coagulant heparin derivative is being investigated as an adjunctive therapy for severe malaria, and further research into the receptor–ligand interactions underlying rosetting may reveal additional therapeutic approaches to reduce the unacceptably high mortality rate of severe malaria.
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22
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Avril M, Benjamin M, Dols MM, Smith JD. Interplay of Plasmodium falciparum and thrombin in brain endothelial barrier disruption. Sci Rep 2019; 9:13142. [PMID: 31511575 PMCID: PMC6739390 DOI: 10.1038/s41598-019-49530-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Accepted: 08/19/2019] [Indexed: 01/05/2023] Open
Abstract
Recent concepts suggest that both Plasmodium falciparum factors and coagulation contribute to endothelial activation and dysfunction in pediatric cerebral malaria (CM) pathology. However, there is still limited understanding of how these complex inflammatory stimuli are integrated by brain endothelial cells. In this study, we examined how mature-stage P. falciparum infected erythrocytes (IE) interact with tumor necrosis factor α (TNFα) and thrombin in the activation and permeability of primary human brain microvascular endothelial cell (HBMEC) monolayers. Whereas trophozoite-stage P. falciparum-IE have limited effect on the viability of HBMEC or the secretion of pro-inflammatory cytokines or chemokines, except at super physiological parasite-host cell ratios, schizont-stage P. falciparum-IE induced low levels of cell death. Additionally, schizont-stage parasites were more barrier disruptive than trophozoite-stage P. falciparum-IE and prolonged thrombin-induced barrier disruption in both resting and TNFα-activated HBMEC monolayers. These results provide evidence that parasite products and thrombin may interact to increase brain endothelial permeability.
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Affiliation(s)
- Marion Avril
- Seattle Children's Research Institute, Seattle, WA, 98109, USA
| | - Max Benjamin
- Seattle Children's Research Institute, Seattle, WA, 98109, USA
| | | | - Joseph D Smith
- Seattle Children's Research Institute, Seattle, WA, 98109, USA. .,Department of Global Health, University of Washington, Seattle, WA, 98195, USA.
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23
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Binding Heterogeneity of Plasmodium falciparum to Engineered 3D Brain Microvessels Is Mediated by EPCR and ICAM-1. mBio 2019; 10:mBio.00420-19. [PMID: 31138740 PMCID: PMC6538777 DOI: 10.1128/mbio.00420-19] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Cerebral malaria research has been hindered by the inaccessibility of the brain. Here, we have developed an engineered 3D human brain microvessel model that mimics the blood flow rates and architecture of small blood vessels to study how P. falciparum-infected human erythrocytes attach to brain endothelial cells. By studying parasite lines with different adhesive properties, we show that the malaria parasite binding rate is heterogeneous and strongly influenced by physiological differences in flow and whether the endothelium has been previously activated by TNF-α, a proinflammatory cytokine that is linked to malaria disease severity. We also show the importance of human EPCR and ICAM-1 in parasite binding. Our model sheds new light on how P. falciparum binds within brain microvessels and provides a powerful method for future investigations of recruitment of human brain pathogens to the blood vessel lining of the brain. Cerebral malaria is a severe neurological complication associated with sequestration of Plasmodium falciparum-infected erythrocytes (IE) in the brain microvasculature, but the specific binding interactions remain under debate. Here, we have generated an engineered three-dimensional (3D) human brain endothelial microvessel model and studied P. falciparum binding under the large range of physiological flow velocities that occur in both health and disease. Perfusion assays on 3D microvessels reveal previously unappreciated phenotypic heterogeneity in parasite binding to tumor necrosis factor alpha (TNF-α)-activated brain endothelial cells. While clonal parasite lines expressing a group B P. falciparum erythrocyte membrane protein 1 (PfEMP1) present an increase in binding to activated 3D microvessels, P. falciparum-IE expressing DC8-PfEMP1 present a decrease in binding. The differential response to endothelium activation is mediated by surface expression changes of endothelial protein C receptor (EPCR) and intercellular adhesion molecule 1 (ICAM-1). These findings demonstrate heterogeneity in parasite binding and provide evidence for a parasite strategy to adapt to a changing microvascular environment during infection. The engineered 3D human brain microvessel model provides new mechanistic insight into parasite binding and opens opportunities for further studies on malaria pathogenesis and parasite-vessel interactions.
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24
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Blood-Brain Barrier in Cerebral Malaria: Pathogenesis and Therapeutic Intervention. Trends Parasitol 2019; 35:516-528. [PMID: 31147271 DOI: 10.1016/j.pt.2019.04.010] [Citation(s) in RCA: 60] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Revised: 04/25/2019] [Accepted: 04/25/2019] [Indexed: 02/06/2023]
Abstract
Cerebral malaria is a life-threatening complication of malaria caused by the parasite Plasmodium falciparum. The growing problem of drug resistance and the dearth of new antiparasitic drugs are a serious threat to the antimalaria treatment regimes. Studies on humans and the murine model have implicated the disruption of the blood-brain barrier (BBB) in the lethal course of the disease. Therefore, efforts to alleviate the BBB dysfunction could serve as an adjunct therapy. Here, we review the mechanisms associated with the disruption of the BBB. In addition, we discuss the current, still limited, knowledge on the contribution of different cell types, microparticles, and the kynurenine pathway in the regulation of BBB dysfunction, and how these molecules could be used as potential new therapeutic targets.
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25
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Abstract
Malaria is a causative factor in about 500.000 deaths each year world-wide. Cerebral malaria is a particularly severe complication of this disease and thus associated with an exceedingly high mortality. Malaria retinopathy is an ocular manifestation often associated with cerebral malaria, and presumably shares a substantial part of its pathophysiology. Here, we describe that indeed murine malaria retinopathy reproduced the main hallmarks of the corresponding human disease. In the living animal, we were able to follow the circulation and cellular localization of malaria parasites transgenically labelled with GFP via non-invasive in vivo retinal imaging. We found that malaria parasites cross the blood-retinal-barrier and infiltrate the neuroretina, concomitant with an extensive, irreversible, and long-lasting retinal neurodegeneration. Furthermore, anti-malarial treatment with dihydroartemisinin strongly diminished the load of circulating parasites but resolved the symptoms of the retinopathy only in part. In summary, we introduce here a novel preclinical model for human cerebral malaria that is much more directly accessible for studies into disease pathophysiology and development of novel treatment approaches. In vivo retinal imaging may furthermore serve as a valuable tool for the early diagnosis of the human disease.
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