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Plasmodium falciparum and TNF-α Differentially Regulate Inflammatory and Barrier Integrity Pathways in Human Brain Endothelial Cells. mBio 2022; 13:e0174622. [PMID: 36036514 PMCID: PMC9601155 DOI: 10.1128/mbio.01746-22] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Cerebral malaria is a severe complication of Plasmodium falciparum infection characterized by the loss of blood-brain barrier (BBB) integrity, which is associated with brain swelling and mortality in patients. P. falciparum-infected red blood cells and inflammatory cytokines, like tumor necrosis factor alpha (TNF-α), have been implicated in the development of cerebral malaria, but it is still unclear how they contribute to the loss of BBB integrity. Here, a combination of transcriptomic analysis and cellular assays detecting changes in barrier integrity and endothelial activation were used to distinguish between the effects of P. falciparum and TNF-α on a human brain microvascular endothelial cell (HBMEC) line and in primary human brain microvascular endothelial cells. We observed that while TNF-α induced high levels of endothelial activation, it only caused a small increase in HBMEC permeability. Conversely, P. falciparum-infected red blood cells (iRBCs) led to a strong increase in HBMEC permeability that was not mediated by cell death. Distinct transcriptomic profiles of TNF-α and P. falciparum in HBMECs confirm the differential effects of these stimuli, with the parasite preferentially inducing an endoplasmic reticulum stress response. Our results establish that there are fundamental differences in the responses induced by TNF-α and P. falciparum on brain endothelial cells and suggest that parasite-induced signaling is a major component driving the disruption of the BBB during cerebral malaria, proposing a potential target for much needed therapeutics.
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Jain V, Thomas T, Basak S, Sharma RK, Singh N. Sequential dysregulated plasma levels of angiopoietins (ANG-2 and ratios of ANG-2/ANG-1) are associated with malaria severity and mortality among hospital admitted cases in South Bastar Region of Chhattisgarh, Central India. Pathog Glob Health 2022; 116:47-58. [PMID: 34308785 PMCID: PMC8812749 DOI: 10.1080/20477724.2021.1953685] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Cerebral malaria (CM) is one of the most severe forms of P. falciparum infection, with an associated high case-fatality rate. Angiopoietins (ANG-1 and ANG-2) are important biomarkers of endothelial activation and dysfunction. This study was carried out in Maharani Hospital and associated Medical College, Jagdalpur, CG, Central India from 2010 to 2014. Based on the treatment recovery patterns, cases (n = 65) were classified as mild malaria with rapid recovery (MM-RR), n= 14; non-cerebral severe malaria with moderately fast recovery (NCSM-MFR), n= 9; CM survivors with slow recovery (CMS-SR), n= 36 and deteriorated CM non-survivors (Det-CMNS), n= 6. Plasma levels (pg/ml) of ANG-1 and ANG-2 were measured by ELISA in all the samples at the time of hospital admission and 48 hours of treatment. Levels were also measured in available samples at the third time point (time of discharge for survivors or 72 hours post-treatment in fatal cases). Data analysis was done by appropriate statistical tests using Stata 11.0 and SPSS 25.0 software. At the time of admission, ANG-2 and ratios of ANG-2/ANG-1 significantly distinguished Det-CMNS cases from MM-RR and NCSM-MFR cases with good AUC scores (0.8-0.9). Further, Det-CMNS cases could also be distinguished from MM-RR, NCSM-MFR, and CMS-SR cases by ANG-2 (AUC scores 0.9) and ratios of ANG-2/ANG-1 (AUC: 0.8-0.9) at 48 hours of treatment. Paired analysis of sequential measurement of angiopoietins revealed that compared to admission levels, the ratios of ANG-2/ANG-1 significantly declined 48 hours after treatment in MM-RR (p= 0.041), NCSM-MFR (p= 0.050), and CMS-SR (p= 0.0002) cases but not in cases of Det-CMNS (p= 0.916). In conclusion, plasma levels of ANG-2 and ratios of ANG-2/ANG-1 may serve as good biomarkers to distinguish the malaria severity at the time of hospital admission and recovery patterns upon treatment in Central India.
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Affiliation(s)
- Vidhan Jain
- Department of Virology and Zoonotic Diseases, ICMR-National Institute of Research in Tribal Health, Jabalpur, MP, India
| | - Trilok Thomas
- Department of Virology and Zoonotic Diseases, ICMR-National Institute of Research in Tribal Health, Jabalpur, MP, India
| | - Sanjay Basak
- Former District Malaria Officer, Maharani Hospital and Associated Medical College Jagdalpur, Chhattisgarh, India
| | - Ravendra Kumar Sharma
- Department of Statistics, ICMR-National Institute of Medical Statistics, ICMR Campus, New Delhi, India
| | - Neeru Singh
- Department of Virology and Zoonotic Diseases, ICMR-National Institute of Research in Tribal Health, Jabalpur, MP, India
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Onohuean H, Alagbonsi AI, Usman IM, Iceland Kasozi K, Alexiou A, Badr RH, Batiha GES, Ezeonwumelu JOC. Annona muricata Linn and Khaya grandifoliola C.DC. Reduce Oxidative Stress In Vitro and Ameliorate Plasmodium berghei-Induced Parasitemia and Cytokines in BALB/c Mice. J Evid Based Integr Med 2021; 26:2515690X211036669. [PMID: 34350806 PMCID: PMC8358498 DOI: 10.1177/2515690x211036669] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Background. Annona muricata and Khaya grandifoliola are ethnomedicinally used for the treatment of malaria and have been experimentally shown to have an anti-plasmodial effect, but the mechanisms involved are not fully understood. This study investigated the effect of the ethanol extracts of their leaves on parasitemia, radical scavenging and cytokines in Plasmodium berghei ANKA-infected BALB/c mice. Methods. BALB/c mice were infected with P. berghei and treated with chloroquine, A. muricata or K. grandifoliola extract for 4 days. The percentage of parasitemia and the level of cytokine expression were determined after treatment. Trace element, phytochemical and nitric oxide (NO) scavenging activity, 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging properties assays were done to study the antioxidant effects of AN and KG in vitro. Results. P. berghei consistently increased parasitemia in BALB/c mice. The tested doses (100-, 200-, and 400 mg/kg) of A. muricata and K. grandifoliola attenuated the P. berghei-induced elevation of parasitemia and cytokines (TNF-α, IL-5, and IL-6) in vivo during the experimental period, though not as much as chloroquine. Moreover, both extracts scavenged the DPPH and NO radicals, though A. muricata had more anti-oxidant effect than K. grandifoliola in-vitro. Conclusion. The ethanol extracts of A. muricata and K. grandifoliola reduce parasitemia in P. berghei-treated mice BALB/c by scavenging free radicals and reducing cytokines, though the extracts were not as effective as chloroquine.
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Affiliation(s)
- Hope Onohuean
- Biomolecules, Metagenomics, Endocrine and Tropical Disease Research Group (BMETDREG), Kampala International University, Western Campus, Ishaka-Bushenyi, Uganda.,Biopharmaceutics Unit, Department of Pharmacology and Toxicology, Kampala International University Western Campus, Ishaka-Bushenyi, Uganda
| | - Abdullateef I Alagbonsi
- Physiology Unit, Department of Clinical Biology, School of Medicine and Pharmacy, University of Rwanda College of Medicine and Health Sciences, Huye, Republic of Rwanda
| | - Ibe M Usman
- Biomolecules, Metagenomics, Endocrine and Tropical Disease Research Group (BMETDREG), Kampala International University, Western Campus, Ishaka-Bushenyi, Uganda.,Department of Anatomy, Faculty of Biomedical Sciences, Kampala International University, Western Campus, Ishaka-Bushenyi, Uganda
| | | | - Athanasios Alexiou
- Novel Global Community Educational Foundation, Hebersham, New South Wales, Australia.,AFNP Med Austria, Wien, Austria
| | - Reem H Badr
- Department of Plant Physiology Botany and Microbiology, Faculty of Science, Alex University, Egypt
| | - Gaber El-Saber Batiha
- Department of Pharmacology and Therapeutics, Faculty of Veterinary Medicine, Damanhour University, Damanhour, El Beheira, Egypt
| | - Joseph O C Ezeonwumelu
- Biomolecules, Metagenomics, Endocrine and Tropical Disease Research Group (BMETDREG), Kampala International University, Western Campus, Ishaka-Bushenyi, Uganda.,Department of Clinical Pharmacy and Biopharmacy, School of Pharmacy, Kampala International University, Western Campus, Ishaka-Bushenyi, Uganda
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Eisenhut M. The Identification of Native Epitopes Eliciting a Protective High-Affinity Immunoglobulin Subclass Response to Blood Stages of Plasmodium falciparum: Protocol for Observational Studies. JMIR Res Protoc 2020; 9:e15690. [PMID: 32706743 PMCID: PMC7395252 DOI: 10.2196/15690] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Revised: 03/20/2020] [Accepted: 05/27/2020] [Indexed: 11/13/2022] Open
Abstract
Background Antibodies to blood stages protective against complications of Plasmodium falciparum infection were found to be of immunoglobulin G 1 (IgG1) and IgG3 subclasses and of high affinity to the target epitopes. These target epitopes cannot be characterized using recombinant antigens because of a lack of appropriate glycosylation, phosphorylation, methylation, and bisulfide bond formation, which determine the structure of conformational and nonlinear epitopes within the tertiary and quaternary structures of native P. falciparum antigens. Objective This study aims to develop a method for the comprehensive detection of all P. falciparum schizont antigens, eliciting a protective immune response. Methods Purified parasitophorous vacuole membrane–enclosed merozoite structures (PEMSs) containing native schizont antigens are initially generated, separated by two-dimensional (2D) gel electrophoresis and blotted onto nitrocellulose. Antigens eliciting a protective antibody response are visualized by incubation with sera from patients with clinical immunity. This is followed by the elution of low-affinity antibodies with urea and detection of protective antibody responses by incubation with anti-IgG1 and anti-IgG3 antibodies, which were conjugated to horseradish peroxidase. This is followed by visualization with a color reaction. Blot signals are normalized by relating to the intensity of blot staining with a reference antibody and housekeeping antigens. Results are corrected for intensity of exposure by the relation of antibody responses to global P. falciparum antibody titers. Antigens eliciting the protective responses are identified as immunorelevant from the comparison of spot positions, indicating high-affinity IgG1 or IgG3 responses on the western blot, which is unique to or consistently more intensive in clinically immune individuals compared with nonimmune individuals. The results obtained are validated by using affinity chromatography. Results Another group previously applied 2D western blotting to analyze antibody responses to P. falciparum. The sera of patients allowed the detection of 42 antigenic spots on the 2D immunoblot. The spots detected were excised and subjected to mass spectrometry for identification. A total of 19 protein spots were successfully identified and corresponded to 13 distinct proteins. Another group used immunoaffinity chromatography to identify antigens bound by IgGs produced by mice with enhanced immunity to Plasmodium yoelii. Immunorelevant antigens were isolated and identified by immobilizing immunoglobulin from immune mice to a Sephadex column and then passing a blood-stage antigen mixture through the column followed by the elution of specific bound antigens with sodium deoxycholate and the identification of those antigens by western blotting with specific antibodies. Conclusions 2D western blotting using native antigens has the potential to identify antibody responses selective for specific defined isomeric forms of the same protein, including isoforms (protein species) generated by posttranscriptional modifications such as phosphorylation, glycosylation, and methylation. The process involved in 2D western blotting enables highly sensitive detection, high resolution, and preservation of antibody responses during blotting. Validation by immunoaffinity chromatography can compensate for the antigen loss associated with the blotting process. It has the potential for indirect quantification of protective antibody responses by enabling quantification of the amount of eluted antibody bound antigens through mass spectrometry. International Registered Report Identifier (IRRID) PRR1-10.2196/15690
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Affiliation(s)
- Michael Eisenhut
- Luton&Dunstable University Hospital NHS Foundation Trust, Luton, United Kingdom
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Joste V, Maurice L, Bertin GI, Aubouy A, Boumédiène F, Houzé S, Ajzenberg D, Argy N, Massougbodji A, Dossou-Dagba I, Alao MJ, Cot M, Deloron P, Faucher JF. Identification of Plasmodium falciparum and host factors associated with cerebral malaria: description of the protocol for a prospective, case-control study in Benin (NeuroCM). BMJ Open 2019; 9:e027378. [PMID: 31142528 PMCID: PMC6549734 DOI: 10.1136/bmjopen-2018-027378] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
INTRODUCTION In 2016, an estimated 216 million cases and 445 000 deaths of malaria occurred worldwide, in 91 countries. In Benin, malaria causes 26.8% of consultation and hospitalisation motif in the general population and 20.9% in children under 5 years old.The goal of the NeuroCM project is to identify the causative factors of neuroinflammation in the context of cerebral malaria. There are currently very few systematic data from West Africa on the aetiologies and management of non-malarial non-traumatic coma in small children, and NeuroCM will help to fill this gap. We postulate that an accurate understanding of molecular and cellular mechanisms involved in neuroinflammation may help to define efficient strategies to prevent and manage cerebral malaria. METHODS AND ANALYSIS This is a prospective, case-control study comparing cerebral malaria to uncomplicated malaria and non-malarial non-traumatic coma. This study takes place in Benin, precisely in Cotonou for children with coma and in Sô-Ava district for children with uncomplicated malaria. We aim to include 300 children aged between 24 and 71 months and divided in three different clinical groups during 12 months (from December 2017 to November 2018) with a 21 to 28 days follow-up for coma. Study data, including clinical, biological and research results will be collected and managed using CSOnline-Ennov Clinical. ETHICS AND DISSEMINATION Ethics approval for the NeuroCM study has been obtained from Comité National d'Ethique pour la Recherche en santé of Benin (n°67/MS/DC/SGM/DRFMT/CNERS/SA; 10/17/2017). NeuroCM study has also been approved by Comité consultatif de déontologie et d'éthique of Institut de Recherche pour le Développement (IRD; 10/24/2017). The study results will be disseminated through the direct consultations with the WHO's Multilateral Initiative on Malaria (TDR-MIM) and Roll Back Malaria programme, through scientific meetings and peer-reviewed publications in scientific or medical journals, and through guidelines and booklets.
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Affiliation(s)
| | - Laurine Maurice
- MERIT, Sorbonne Paris Cité, IRD, 75006, Paris, France
- PHARMADEV, Université de Toulouse, IRD, UPS, France, Toulouse, France
| | | | - Agnès Aubouy
- PHARMADEV, Université de Toulouse, IRD, UPS, France, Toulouse, France
| | | | - Sandrine Houzé
- MERIT, Sorbonne Paris Cité, IRD, 75006, Paris, France
- Parasitology Laboratory, Hopital Bichat - Claude-Bernard, Paris, France
| | | | - Nicolas Argy
- MERIT, Sorbonne Paris Cité, IRD, 75006, Paris, France
- Parasitology Laboratory, Hopital Bichat - Claude-Bernard, Paris, France
| | | | | | - Maroufou Jules Alao
- Paediatric Department, Mother and Child University and Hospital Center (CHU-MEL), Cotonou, Benin
| | - Michel Cot
- MERIT, Sorbonne Paris Cité, IRD, 75006, Paris, France
| | | | - Jean-François Faucher
- Tropical Neuroepidemiology, INSERM UMR 1094, Limoges, France
- Infectious diseases and tropical medicine department, Limoges University Hospital, Limoges, France
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6
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O'Brien NF, Mutatshi Taty T, Moore-Clingenpeel M, Bodi Mabiala J, Mbaka Pongo J, Ambitapio Musungufu D, Uchama M, Yotebieng M. Transcranial Doppler Ultrasonography Provides Insights into Neurovascular Changes in Children with Cerebral Malaria. J Pediatr 2018; 203:116-124.e3. [PMID: 30224088 DOI: 10.1016/j.jpeds.2018.07.075] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/30/2018] [Revised: 07/14/2018] [Accepted: 07/24/2018] [Indexed: 01/21/2023]
Abstract
OBJECTIVE To evaluate neurovascular changes in pediatric patients with cerebral malaria. STUDY DESIGN African children with cerebral malaria were enrolled and underwent daily transcranial Doppler ultrasound (TCD) examinations through hospital day 8, discharge, or death. Neurologic outcomes were assessed 2 weeks after enrollment. RESULTS In total, 160 children with cerebral malaria and 155 comparison patients were included. In patients with cerebral malaria, TCD flow changes characterized as hyperemia were seen in 42 (26%), low flow in 46 (28%), microvascular obstruction in 35 (22%), cerebral vasospasm in 21 (13%), and isolated posterior hyperemia in 7 (4%). Most had a single neurovascular phenotype observed throughout participation. Among comparison patients, 76% had normal TCD findings (P < .001). Impaired autoregulation was present in 80% of cases (transient hyperemic response ratio 1.01 ± 0.03) but improved through day 4 (1.1 ± 0.02, P = .014). Overall mortality was 24% (n = 39). Neurologic deficits were evident in 21% of survivors. Children meeting criteria for vasospasm were most likely to survive with sequelae, and children meeting criteria for low flow were most likely to die. Autoregulation was better in children with a normal neurologic outcome (1.09, 95% CI 1.06-1.12) than in others (0.98, 95% CI 0.95-1) (P ≤ .001). CONCLUSIONS Several distinct changes in TCD measurements were identified in children with cerebral malaria that permitted phenotypic grouping. Groups had distinct associations with neurologic outcomes. Validation of pathogenic mechanisms associated with each phenotype may aid in developing TCD as a portable, easy-to-use tool to help guide targeted adjunctive therapy in cerebral malaria aimed at causative mechanisms of injury on an individual level.
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Affiliation(s)
- Nicole Fortier O'Brien
- Department of Pediatrics, Division of Critical Care Medicine, Nationwide Children's Hospital, The Ohio State University, Columbus, OH.
| | - Tshimanga Mutatshi Taty
- Department of Pediatrics, University Clinics of Kinshasa, Kinshasa, Democratic Republic of the Congo
| | | | - Joseph Bodi Mabiala
- Department of Pediatrics, University Clinics of Kinshasa, Kinshasa, Democratic Republic of the Congo
| | - Jean Mbaka Pongo
- University of Science and Technology, General Referral Hospital of Lodja, Lodja, Democratic Republic of the Congo
| | - Davin Ambitapio Musungufu
- Department of Pediatrics, Medical Evangelical Center of Nyankunde, Bunia, Democratic Republic of the Congo
| | - Mananu Uchama
- Department of Pediatrics, Medical Evangelical Center of Nyankunde, Bunia, Democratic Republic of the Congo
| | - Marcel Yotebieng
- Division of Epidemiology, College of Public Health, The Ohio State University, Columbus, OH
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Hoffmann A, Wassmer SC. New Syndromes Identified by Neuroimaging during Cerebral Malaria. Am J Trop Med Hyg 2018; 98:349-350. [PMID: 29313484 PMCID: PMC5929216 DOI: 10.4269/ajtmh.17-0926] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Angelika Hoffmann
- Department of Neuroradiology, Heidelberg University Hospital, Heidelberg, Germany
| | - Samuel C Wassmer
- Department of Infection & Immunity, London School of Hygiene & Tropical Medicine, London, United Kingdom
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Yamamoto K, Kato Y, Shinohara K, Kutsuna S, Takeshita N, Hayakawa K, Iwagami M, Kano S, Watanabe S, Ohmagari N. Case Report: Reversible Cerebral Vasoconstriction Syndrome in Cerebral Malaria. Am J Trop Med Hyg 2017; 98:505-507. [PMID: 29260652 DOI: 10.4269/ajtmh.17-0665] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Cerebral malaria is a severe complication of falciparum malaria that occurs infrequently in adults. Here, we describe the case of a 21-year-old man who presented with fever and headache 13 days after returning from a 12-day trip to Kenya and was subsequently diagnosed with falciparum malaria. Complications of cerebral malaria developed within 1 day after the initiation of therapy with intravenous quinine, and the patient entered a deep coma. Magnetic resonance angiography (MRA) revealed multiple vasoconstrictions in his brain. The resulting neurocognitive disorders that persisted after parasite clearance improved gradually, as confirmed by MRA, enabling the patient to perform activities of daily living upon discharge. In this case of cerebral malaria, the MRA findings indicated the involvement of reversible cerebral vasoconstriction syndrome.
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Affiliation(s)
- Kei Yamamoto
- Disease Control and Prevention Center, National Center for Global Health and Medicine, Tokyo, Japan
| | - Yasuyuki Kato
- Disease Control and Prevention Center, National Center for Global Health and Medicine, Tokyo, Japan
| | - Koh Shinohara
- Disease Control and Prevention Center, National Center for Global Health and Medicine, Tokyo, Japan
| | - Satoshi Kutsuna
- Disease Control and Prevention Center, National Center for Global Health and Medicine, Tokyo, Japan
| | - Nozomi Takeshita
- Disease Control and Prevention Center, National Center for Global Health and Medicine, Tokyo, Japan
| | - Kayoko Hayakawa
- Disease Control and Prevention Center, National Center for Global Health and Medicine, Tokyo, Japan
| | - Moritoshi Iwagami
- Department of Tropical Medicine and Malaria, Research Institute, National Center for Global Health and Medicine, Tokyo, Japan
| | - Shigeyuki Kano
- Department of Tropical Medicine and Malaria, Research Institute, National Center for Global Health and Medicine, Tokyo, Japan
| | - Shu Watanabe
- Department of Rehabilitation Medicine, Jikei University School of Medicine, Tokyo, Japan
| | - Norio Ohmagari
- Disease Control and Prevention Center, National Center for Global Health and Medicine, Tokyo, Japan
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Magnetic Resonance Imaging of Cerebral Malaria Patients Reveals Distinct Pathogenetic Processes in Different Parts of the Brain. mSphere 2017; 2:mSphere00193-17. [PMID: 28596990 PMCID: PMC5463026 DOI: 10.1128/msphere.00193-17] [Citation(s) in RCA: 68] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2017] [Accepted: 05/09/2017] [Indexed: 12/02/2022] Open
Abstract
The pathophysiology and molecular mechanisms underlying cerebral malaria (CM) are still poorly understood. Recent neuroimaging studies demonstrated that brain swelling is a common feature in CM and a major contributor to death in pediatric patients. Consequently, determining the precise mechanisms responsible for this swelling could open new adjunct therapeutic avenues in CM patients. Using an MRI scanner with a higher resolution than the ones used in previous reports, we identified two distinct origins of brain swelling in both adult and pediatric patients from India, occurring in distinct parts of the brain. Our results support the hypothesis that both endothelial dysfunction and microvascular obstruction by Plasmodium falciparum-infected erythrocytes make independent contributions to the pathogenesis of CM, providing opportunities for novel therapeutic interventions. The mechanisms underlying the rapidly reversible brain swelling described in patients with cerebral malaria (CM) are unknown. Using a 1.5-Tesla (T) magnetic resonance imaging (MRI) scanner, we undertook an observational study in Rourkela, India, of 11 Indian patients hospitalized with CM and increased brain volume. Among the 11 cases, there were 5 adults and 6 children. All patients had reduced consciousness and various degrees of cortical swelling at baseline. The latter was predominately posterior in distribution. The findings on diffusion-weighted imaging (DWI) and apparent diffusion coefficient (ADC) maps were consistent with vasogenic edema in all cases. Reversibility after 48 to 72 h was observed in >90% of cases. DWI/ADC mismatch suggested the additional presence of cytotoxic edema in the basal nuclei of 5 patients; all of these had perfusion parameters consistent with vascular engorgement and not with ischemic infarcts. Our results suggest that an impairment of the blood-brain barrier is responsible for the brain swelling in CM. In 5 cases, vasogenic edema occurred in conjunction with changes in the basal nuclei consistent with venous congestion, likely to be caused by the sequestration of Plasmodium falciparum-infected erythrocytes. While both mechanisms have been individually postulated to play an important role in the development of CM, this is the first demonstration of their concurrent involvement in different parts of the brain. The clinical and radiological characteristics observed in the majority of our patients are consistent with posterior reversible encephalopathy syndrome (PRES), and we show for the first time a high frequency of PRES in the context of CM. IMPORTANCE The pathophysiology and molecular mechanisms underlying cerebral malaria (CM) are still poorly understood. Recent neuroimaging studies demonstrated that brain swelling is a common feature in CM and a major contributor to death in pediatric patients. Consequently, determining the precise mechanisms responsible for this swelling could open new adjunct therapeutic avenues in CM patients. Using an MRI scanner with a higher resolution than the ones used in previous reports, we identified two distinct origins of brain swelling in both adult and pediatric patients from India, occurring in distinct parts of the brain. Our results support the hypothesis that both endothelial dysfunction and microvascular obstruction by Plasmodium falciparum-infected erythrocytes make independent contributions to the pathogenesis of CM, providing opportunities for novel therapeutic interventions.
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Exported Epoxide Hydrolases Modulate Erythrocyte Vasoactive Lipids during Plasmodium falciparum Infection. mBio 2016; 7:mBio.01538-16. [PMID: 27795395 PMCID: PMC5082902 DOI: 10.1128/mbio.01538-16] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Erythrocytes are reservoirs of important epoxide-containing lipid signaling molecules, including epoxyeicosatrienoic acids (EETs). EETs function as vasodilators and anti-inflammatory modulators in the bloodstream. Bioactive EETs are hydrolyzed to less active diols (dihydroxyeicosatrienoic acids) by epoxide hydrolases (EHs). The malaria parasite Plasmodium falciparum infects host red blood cells (RBCs) and exports hundreds of proteins into the RBC compartment. In this study, we show that two parasite epoxide hydrolases, P. falciparum epoxide hydrolases 1 (PfEH1) and 2 (PfEH2), both with noncanonical serine nucleophiles, are exported to the periphery of infected RBCs. PfEH1 and PfEH2 were successfully expressed in Escherichia coli, and they hydrolyzed physiologically relevant erythrocyte EETs. Mutations in active site residues of PfEH1 ablated the ability of the enzyme to hydrolyze an epoxide substrate. Overexpression of PfEH1 or PfEH2 in parasite-infected RBCs resulted in a significant alteration in the epoxide fatty acids stored in RBC phospholipids. We hypothesize that the parasite disruption of epoxide-containing signaling lipids leads to perturbed vascular function, creating favorable conditions for binding and sequestration of infected RBCs to the microvascular endothelium. The malaria parasite exports hundreds of proteins into the erythrocyte compartment. However, for most of these proteins, their physiological function is unknown. In this study, we investigate two “hypothetical” proteins of the α/β-hydrolase fold family that share sequence similarity with epoxide hydrolases (EHs)—enzymes that destroy bioactive epoxides. Altering EH expression in parasite-infected erythrocytes resulted in a significant change in the epoxide fatty acids stored in the host cell. We propose that these EH enzymes may help the parasite to manipulate host blood vessel opening and inflame the vessel walls as they pass through the circulation system. Understanding how the malaria parasite interacts with its host RBCs will aid in our ability to combat this deadly disease.
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Li G, Wang QS, Lin TT. Alterations in the expression of protease-activated receptor 1 and tumor necrosis factor-α in the basilar artery of rats following a subarachnoid hemorrhage. Exp Ther Med 2016; 11:717-722. [PMID: 26997984 PMCID: PMC4774309 DOI: 10.3892/etm.2016.3010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2014] [Accepted: 10/22/2015] [Indexed: 12/15/2022] Open
Abstract
The present study aimed to investigate the expression of protease-activated receptor 1 (PAR1) and tumor necrosis factor (TNF)-α in a rat model of subarachnoid hemorrhage (SAH)-induced cerebral vasospasm (CVS). The rat models were established by twice injecting blood into the cisterna magna, after which the following experimental groups were established: The normal group, the SAH3d group, the SAH5d group and the SAH7d group. The rats were perfused and the basilar artery was removed for histological examination. The cross-sectional area of the basilar artery lumen was measured using computer software; and the protein expression of PAR1 and TNF-α was detected by immunohistochemistry. The cross-sectional area of the basilar artery of the rats in the SAH model groups was significantly decreased in a time-dependent manner, as compared with the normal group. The protein expression of PAR1 and TNF-α in the SAH3d, SAH5d and SAH7d groups was significantly increased over time (P<0.05), as compared with the normal group. CVS was detected in the basilar artery, and was associated with wall thickening and significant narrowing of the lumen, thus suggesting that the present model may be used for investigating cerebrovascular disease following SAH. The immunohistochemical analyses demonstrated that the protein expression of PAR1 and TNF-α was significantly increased in the basilar artery of the SAH model rats, and were positively correlated with the degree of CVS.
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Affiliation(s)
- Gang Li
- Department of Neurosurgery, Hainan Branch of the China PLA General Hospital, Sanya, Hainan 572013, P.R. China
| | - Qing-Song Wang
- Department of Neurosurgery, Haikou Municipal Hospital, Haikou, Hainan 570208, P.R. China
| | - Ting-Ting Lin
- Department of Neurosurgery, Haikou Municipal Hospital, Haikou, Hainan 570208, P.R. China
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