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Vera IM, Kessler A, Harawa V, Ahmadu A, Keller TE, Ray ST, Taylor TE, Rogerson SJ, Mandala WL, Reyes Gil M, Seydel KB, Kim K. Prothrombotic autoantibodies targeting platelet factor 4/polyanion are associated with pediatric cerebral malaria. J Clin Invest 2024; 134:e176466. [PMID: 38652559 PMCID: PMC11142751 DOI: 10.1172/jci176466] [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: 10/10/2023] [Accepted: 04/09/2024] [Indexed: 04/25/2024] Open
Abstract
BACKGROUNDFeatures of consumptive coagulopathy and thromboinflammation are prominent in cerebral malaria (CM). We hypothesized that thrombogenic autoantibodies contribute to a procoagulant state in CM.METHODSPlasma from children with uncomplicated malaria (UM) (n = 124) and CM (n = 136) was analyzed by ELISA for a panel of 8 autoantibodies including anti-platelet factor 4/polyanion (anti-PF4/P), anti-phospholipid, anti-phosphatidylserine, anti-myeloperoxidase, anti-proteinase 3, anti-dsDNA, anti-β-2-glycoprotein I, and anti-cardiolipin. Plasma samples from individuals with nonmalarial coma (NMC) (n = 49) and healthy controls (HCs) (n = 56) were assayed for comparison. Associations with clinical and immune biomarkers were determined using univariate and logistic regression analyses.RESULTSMedian anti-PF4/P and anti-PS IgG levels were elevated in individuals with malaria infection relative to levels in HCs (P < 0.001) and patients with NMC (PF4/P: P < 0.001). Anti-PF4/P IgG levels were elevated in children with CM (median = 0.27, IQR: 0.19-0.41) compared with those with UM (median = 0.19, IQR: 0.14-0.22, P < 0.0001). Anti-PS IgG levels did not differ between patients with UM and those with CM (P = 0.39). When patients with CM were stratified by malaria retinopathy (Ret) status, the levels of anti-PF4/P IgG correlated negatively with the peripheral platelet count in patients with Ret+ CM (Spearman's rho [Rs] = 0.201, P = 0.04) and associated positively with mortality (OR = 15.2, 95% CI: 1.02-275, P = 0.048). Plasma from patients with CM induced greater platelet activation in an ex vivo assay relative to plasma from patients with UM (P = 0.02), and the observed platelet activation was associated with anti-PF4/P IgG levels (Rs= 0.293, P = 0.035).CONCLUSIONSThrombosis mediated by elevated anti-PF4/P autoantibodies may be one mechanism contributing to the clinical complications of CM.
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Affiliation(s)
- Iset M. Vera
- Division of Infectious Disease and International Medicine, Department of Internal Medicine, University of South Florida, Tampa, Florida, USA
| | - Anne Kessler
- Center for Genomics and Systems Biology, Department of Biology, New York University, New York, New York, USA
| | - Visopo Harawa
- Malawi-Liverpool Wellcome Trust Clinical Research Programme, Blantyre, Malawi
- Biomedical Department, University of Malawi College of Medicine, Blantyre, Malawi
- Blantyre Malaria Project, Kamuzu University of Health Sciences, Blantyre, Malawi
| | - Ajisa Ahmadu
- Malawi-Liverpool Wellcome Trust Clinical Research Programme, Blantyre, Malawi
| | - Thomas E. Keller
- Division of Infectious Disease and International Medicine, Department of Internal Medicine, University of South Florida, Tampa, Florida, USA
| | - Stephen T.J. Ray
- Malawi-Liverpool Wellcome Trust Clinical Research Programme, Blantyre, Malawi
- Blantyre Malaria Project, Kamuzu University of Health Sciences, Blantyre, Malawi
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford, Oxford, United Kingdom
- Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool, United Kingdom
| | - Terrie E. Taylor
- Blantyre Malaria Project, Kamuzu University of Health Sciences, Blantyre, Malawi
- Department of Osteopathic Medical Specialties, Michigan State University, East Lansing, Michigan, USA
| | - Stephen J. Rogerson
- Department of Medicine (RMH), and
- Department of Infectious Diseases, Doherty Institute, The University of Melbourne, Melbourne, Australia
| | - Wilson L. Mandala
- Malawi-Liverpool Wellcome Trust Clinical Research Programme, Blantyre, Malawi
- Biomedical Department, University of Malawi College of Medicine, Blantyre, Malawi
- Academy of Medical Sciences, Malawi University of Science and Technology, Thyolo, Malawi
| | - Morayma Reyes Gil
- Department of Pathology, Albert Einstein College of Medicine and Montefiore Medical Center, Bronx, New York, USA
| | - Karl B. Seydel
- Blantyre Malaria Project, Kamuzu University of Health Sciences, Blantyre, Malawi
- Department of Osteopathic Medical Specialties, Michigan State University, East Lansing, Michigan, USA
| | - Kami Kim
- Division of Infectious Disease and International Medicine, Department of Internal Medicine, University of South Florida, Tampa, Florida, USA
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Li J, Saidi AM, Seydel K, Lillehoj PB. Rapid diagnosis and prognosis of malaria infection using a microfluidic point-of-care immunoassay. Biosens Bioelectron 2024; 250:116091. [PMID: 38325074 DOI: 10.1016/j.bios.2024.116091] [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: 11/15/2023] [Revised: 01/23/2024] [Accepted: 01/28/2024] [Indexed: 02/09/2024]
Abstract
Malaria is a major cause of illness and death worldwide. Rapid diagnostic tests are the most widely used tool for detecting malaria infection, however, they only provide binary results and lack the sensitivity needed to detect many asymptomatic infections. Molecular assays for quantifying malaria biomarkers offer higher detection sensitivity, however, they are time-consuming, and require expert training and expensive equipment, making them unsuitable for use in most of Africa. To address the need for simple, accurate and field-deployable malaria diagnostic tests, we have developed a microfluidic point-of-care (mPOC) immunoassay for rapid quantification of Plasmodium falciparum histidine-rich protein 2 (PfHRP2), a malaria parasite biomarker, in whole blood. This device features two diagnostic modes for detecting PfHRP2 at low (100's pg/mL) and high (1,000's ng/mL) concentrations, making it useful for multiple diagnostic applications, including the detection of asymptomatic infection, prediction of disease outcomes and diagnosis of cerebral malaria. Measurements of PfHRP2 in blood samples from malaria patients demonstrates that this platform offers similar accuracy as an ultra-sensitive PfHRP2 enzyme-linked immunosorbent assay (ELISA) test, while being 12× faster and simpler to use. This mPOC immunoassay can be deployed in rural health centers to assist clinicians in diagnosing and triaging malaria patients, ultimately improving patient outcomes.
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Affiliation(s)
- Jiran Li
- Department of Mechanical Engineering, Rice University, Houston, TX 77005, USA
| | - Alexuse M Saidi
- Blantyre Malaria Project, Kamuzu University of Health Sciences, Blantyre, Malawi
| | - Karl Seydel
- Blantyre Malaria Project, Kamuzu University of Health Sciences, Blantyre, Malawi; Department of Osteopathic Medical Specialties, College of Osteopathic Medicine, Michigan State University, East Lansing, MI 48864, USA
| | - Peter B Lillehoj
- Department of Mechanical Engineering, Rice University, Houston, TX 77005, USA; Department of Bioengineering, Rice University, Houston, TX 77030, USA.
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Nguyen ST, Du D, Wychrij D, Cain MD, Wu Q, Klein RS, Russo I, Goldberg DE. Histidine-rich protein II nanoparticle delivery of heme iron load drives endothelial inflammation in cerebral malaria. Proc Natl Acad Sci U S A 2023; 120:e2306318120. [PMID: 37307435 PMCID: PMC10293821 DOI: 10.1073/pnas.2306318120] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Accepted: 05/19/2023] [Indexed: 06/14/2023] Open
Abstract
Histidine-rich protein II (HRPII) is secreted by Plasmodium falciparum during the blood stage of malaria infection. High plasma levels of HRPII are associated with cerebral malaria, a severe and highly fatal complication of malaria. HRPII has been shown to induce vascular leakage, the hallmark of cerebral malaria, in blood-brain barrier (BBB) and animal models. We have discovered an important mechanism for BBB disruption that is driven by unique features of HRPII. By characterizing serum from infected patients and HRPII produced by P. falciparum parasites in culture, we found that HRPII exists in large multimeric particles of 14 polypeptides that are richly laden with up to 700 hemes per particle. Heme loading of HRPII is required for efficient binding and internalization via caveolin-mediated endocytosis in hCMEC/D3 cerebral microvascular endothelial cells. Upon acidification of endolysosomes, two-thirds of the hemes are released from acid-labile binding sites and metabolized by heme oxygenase 1, generating ferric iron and reactive oxygen species. Subsequent activation of the NLRP3 inflammasome and IL-1β secretion resulted in endothelial leakage. Inhibition of these pathways with heme sequestration, iron chelation, or anti-inflammatory drugs protected the integrity of the BBB culture model from HRPII:heme. Increased cerebral vascular permeability was seen after injection of young mice with heme-loaded HRPII (HRPII:heme) but not with heme-depleted HRPII. We propose that during severe malaria infection, HRPII:heme nanoparticles in the bloodstream deliver an overwhelming iron load to endothelial cells to cause vascular inflammation and edema. Disrupting this process is an opportunity for targeted adjunctive therapies to reduce the morbidity and mortality of cerebral malaria.
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Affiliation(s)
- Suong T. Nguyen
- Division of Infectious Diseases, Department of Pediatrics, Washington University School of Medicine, St. Louis, MO63110
- Division of Infectious Diseases, Department of Medicine, Washington University School of Medicine, St. Louis, MO63110
| | - Daniel Du
- Division of Infectious Diseases, Department of Medicine, Washington University School of Medicine, St. Louis, MO63110
| | - Daniel Wychrij
- Division of Infectious Diseases, Department of Medicine, Washington University School of Medicine, St. Louis, MO63110
| | - Matthew D. Cain
- Division of Infectious Diseases, Department of Medicine, Washington University School of Medicine, St. Louis, MO63110
| | - Qingping Wu
- Division of Infectious Diseases, Department of Medicine, Washington University School of Medicine, St. Louis, MO63110
| | - Robyn S. Klein
- Division of Infectious Diseases, Department of Medicine, Washington University School of Medicine, St. Louis, MO63110
| | - Ilaria Russo
- Division of Infectious Diseases, Department of Medicine, Washington University School of Medicine, St. Louis, MO63110
| | - Daniel E. Goldberg
- Division of Infectious Diseases, Department of Medicine, Washington University School of Medicine, St. Louis, MO63110
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO63110
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Lin Y, Tebulo A, Small D, Seydel K, Taylor T, Zhang B. Using Malarial Retinopathy to Improve the Diagnosis of Pediatric Cerebral Malaria. Am J Trop Med Hyg 2023; 108:69-75. [PMID: 36509055 PMCID: PMC9833082 DOI: 10.4269/ajtmh.22-0547] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2022] [Accepted: 10/03/2022] [Indexed: 12/14/2022] Open
Abstract
In malaria endemic areas, a high proportion of children have detectable parasitemia but show no clinical symptoms. When comatose from a cause other than malaria, this group confounds the cerebral malaria (CM) definition, making accurate diagnosis challenging. One important biomarker of CM is malarial retinopathy, a set of specific features visible in the ocular fundus. In this study, we quantified the contribution of malarial retinopathy in discriminating malaria-caused coma from non-malaria-caused coma. We estimated that 10% of our study cohort of N = 1,192 patients who met the WHO clinical definition of CM in Malawi had non-malarial coma based on a Gaussian mixture model using the parasite protein Plasmodium falciparum histidine-rich protein-2. A classification based on platelets, white blood cells, and retinopathy significantly improved the discriminative power of a previously established model including only platelets plus white blood cells (area under the receiver operating characteristic curve: 0.89 versus 0.75, P value < 0.001). We conclude that malarial retinopathy is highly predictive of malaria-caused versus non-malaria-caused coma and recommend that an ocular funduscopic examination to determine malarial retinopathy status be included in the assessment of parasitemic comatose African children.
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Affiliation(s)
- Yuzhou Lin
- Department of Statistics, Harvard University, Cambridge, Massachusetts
| | - Andrew Tebulo
- Blantyre Malaria Project, Kamuzu University of Health Sciences, Blantyre, Malawi
| | - Dylan Small
- Department of Statistics and Data Science, The Wharton School, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Karl Seydel
- Blantyre Malaria Project, Kamuzu University of Health Sciences, Blantyre, Malawi
- Department of Osteopathic Medical Specialties, Michigan State University, East Lansing, Michigan
| | - Terrie Taylor
- Blantyre Malaria Project, Kamuzu University of Health Sciences, Blantyre, Malawi
- Department of Osteopathic Medical Specialties, Michigan State University, East Lansing, Michigan
| | - Bo Zhang
- Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Center, Seattle, Washington
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5
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Tembo D, Mwanza S, Mwaba C, Dallah I, wa Somwe S, Seydel KB, Birbeck GL. Risk factors for acute kidney injury at presentation among children with CNS malaria: a case control study. Malar J 2022; 21:310. [PMID: 36316704 PMCID: PMC9624036 DOI: 10.1186/s12936-022-04327-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Accepted: 10/18/2022] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Recent research has established that acute kidney injury (AKI) is a common problem in severe paediatric malaria. Limited access to kidney diagnostic studies in the low resources settings where malaria is common has constrained research on this important problem. METHODS Enrolment data from an ongoing clinical trial of antipyretics in children with central nervous system (CNS) malaria, CNS malaria being malaria with seizures or coma, was used to identify risk factors for AKI at presentation. Children 2-11 years old with CNS malaria underwent screening and enrollment assessments which included demographic and anthropomorphic data, clinical details regarding the acute illness, and laboratory studies including creatinine (Cr), quantitative parasite count (qPC), quantitative histidine rich protein 2 (HRP2), lactate, and bilirubin levels. Children with a screening Cr > 106 µmol/l were excluded from the study due to the potential nephrotoxic effects of the study drug. To identify risk factors for AKI at the time of admission, children who were enrolled in the study were categorized as having AKI using estimates of their baseline (i.e. before this acute illness) kidney function and creatinine at enrollment applying the Kidney Disease: Improving Global Outcome (KDIGO) 2012 guidelines. Logistic regressions and a multivariate model were used to identify clinical and demographic risk factors for AKI at presentation among those children enrolled in the study. RESULTS 465 children were screened, 377 were age-appropriate with CNS malaria, 22 (5.8%) were excluded due to Cr > 106 µmol/l, and 209 were enrolled. Among the 209, AKI using KDIGO criteria was observed in 134 (64.1%). One child required dialysis during recovery. Risk factors for AKI in both the logistic regression and multivariate models included: hyperpyrexia (OR 3.36; 95% CI 1.39-8.12) and age with older children being less likely to have AKI (OR 0.72; 95% CI 0.62-0.84). CONCLUSION AKI is extremely common among children presenting with CNS malaria. Hyperpyrexia with associated dehydration may contribute to the AKI or may simply be a marker for a more inflammatory systemic response that is also affecting the kidney. Appropriate fluid management in children with CNS malaria and AKI may be challenging since generous hydration to support kidney recovery could worsen malaria-induced cerebral oedema in this critically ill population. Trial registration https://clinicaltrials.gov/ct2/show/NCT03399318.
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Affiliation(s)
- Derby Tembo
- Department of Paediatrics and Child Health, Chipata Central Hospital, Chipata, Zambia
| | - Suzanna Mwanza
- Department of Paediatrics and Child Health, Chipata Central Hospital, Chipata, Zambia
| | - Chisambo Mwaba
- grid.12984.360000 0000 8914 5257Dept. of Paediatric & Child Health, University of Zambia School of Medicine, Lusaka, Zambia
| | - Ifunanya Dallah
- grid.16416.340000 0004 1936 9174Department of Neurology, University of Rochester, Rochester, NY 14642 USA
| | - Somwe wa Somwe
- University Teaching Hospitals, Neurology Research Office, Lusaka, Zambia
| | - Karl B. Seydel
- Blantyre Malaria Project, Kamuzu University of Health Sciences, Blantyre, Malawi ,grid.17088.360000 0001 2150 1785Dept. of Osteopathic Medical Specialties, College of Osteopathic Medicine, Michigan State University, East Lansing, MI USA
| | - Gretchen L. Birbeck
- grid.12984.360000 0000 8914 5257Dept. of Paediatric & Child Health, University of Zambia School of Medicine, Lusaka, Zambia ,grid.16416.340000 0004 1936 9174Department of Neurology, University of Rochester, Rochester, NY 14642 USA ,University Teaching Hospitals Children’s Hospital, Lusaka, Zambia
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6
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Chilombe MB, McDermott MP, Seydel KB, Mathews M, Mwenechanya M, Birbeck GL. Aggressive antipyretics in central nervous system malaria: Study protocol of a randomized-controlled trial assessing antipyretic efficacy and parasite clearance effects (Malaria FEVER study). PLoS One 2022; 17:e0268414. [PMID: 36206262 PMCID: PMC9543763 DOI: 10.1371/journal.pone.0268414] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Accepted: 08/15/2022] [Indexed: 11/06/2022] Open
Abstract
BACKGROUND Malaria remains a major public health challenge in Africa where annually, ~250,000 children with malaria experience a neurologic injury with subsequent neuro-disability. Evidence indicates that a higher temperature during the acute illness is a risk factor for post-infectious neurologic sequelae. As such, aggressive antipyretic therapy may be warranted among children with complicated malaria at substantial risk of brain injury. Previous clinical trials conducted primarily in children with uncomplicated malaria and using only a single antipyretic medication have shown limited benefits in terms of fever reduction; however, no studies to date have examined malaria fever management using dual therapies. In this clinical trial of aggressive antipyretic therapy, children hospitalized with central nervous system (CNS) malaria will be randomized to usual care (acetaminophen every 6 hours for a temperature ≥ 38.5°C) vs. prophylactic acetaminophen and ibuprofen every 6 hours for 72 hours. METHODS In this double-blinded, placebo controlled, two-armed clinical trial, we will enroll 284 participants from three settings at Queen Elizabeth Central Hospital in Blantyre, Malawi; at the University Teaching Hospitals Children's Hospital in Lusaka, Zambia and at Chipata Central Hospital, Chipata, Zambia. Parents or guardians must provide written informed consent. Eligible participants are 2-11 years with evidence of P. falciparum malaria infection by peripheral blood smear or rapid diagnostic test with CNS symptoms associated with malaria. Eligible children will receive treatment allocation randomization either to standard of care for fever management or to prophylactic, scheduled treatment every 6 hours for 72 hours with dual antipyretic therapies using acetaminophen and ibuprofen. Assignment to treatment groups will be with 1:1 allocation using blocked randomization. The primary outcome will be maximum temperature in the 72 hours after enrolment. Secondary outcomes include parasite clearance as determined by quantitative Histidine Rich Protein II and seizures through 72 hours after enrolment. DISCUSSION This clinical trial seeks to challenge the practice paradigm of limited fever treatment based upon hyperpyrexia by evaluating the fever-reduction efficacy of more aggressive antipyretic using two antipyretics and prophylactic administration and will elucidate the impact of antipyretics on parasite clearance and acute symptomatic seizures. If aggressive antipyretic therapy is shown to safely reduce the maximum temperature, a clinical trial evaluating the neuroprotective effects of temperature reduction in CNS malaria is warranted.
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Affiliation(s)
- Moses B. Chilombe
- Blantyre Malaria Project, Queen Elizabeth Central Hospital, Blantyre, Malawi
| | - Michael P. McDermott
- Department of Biostatistics and Computational Biology, University of Rochester, Rochester, New York, United States of America
| | - Karl B. Seydel
- Department of Osteopathic Medical Specialties, College of Osteopathic Medicine, Michigan State University, East Lansing, Michigan, United States of America
| | - Manoj Mathews
- University Teaching Hospitals Children’s Hospital, Lusaka, Zambia
| | | | - Gretchen L. Birbeck
- University Teaching Hospitals Children’s Hospital, Lusaka, Zambia
- University of Zambia School of Medicine, Lusaka, Zambia
- Department of Neurology, University of Rochester, Rochester, New York, United States of America
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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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Uyoga S, Olupot-Olupot P, Connon R, Kiguli S, Opoka RO, Alaroker F, Muhindo R, Macharia AW, Dondorp AM, Gibb DM, Walker AS, George EC, Maitland K, Williams TN. Sickle cell anaemia and severe Plasmodium falciparum malaria: a secondary analysis of the Transfusion and Treatment of African Children Trial (TRACT). THE LANCET. CHILD & ADOLESCENT HEALTH 2022; 6:606-613. [PMID: 35785794 PMCID: PMC7613576 DOI: 10.1016/s2352-4642(22)00153-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Revised: 04/27/2022] [Accepted: 04/29/2022] [Indexed: 11/18/2022]
Abstract
BACKGROUND Sickle cell anaemia (SCA) has historically been associated with high levels of childhood mortality in Africa. Although malaria has a major contribution to this mortality, to date, the clinical pathology of malaria among children with SCA has been poorly described. We aimed to explore the relationship between SCA and Plasmodium falciparum malaria in further detail by investigating the burden and severity of malaria infections among children recruited with severe anaemia to the TRACT trial of blood transfusion in Africa. METHODS This study is a post-hoc secondary analysis of the TRACT trial data, conducted after trial completion. TRACT was an open-label, multicentre, factorial, randomised controlled trial enrolling children aged 2 months to 12 years who presented with severe anaemia (haemoglobin <6·0 g/dL) to four hospitals in Africa. This secondary analysis is restricted to Uganda, where the birth prevalence of SCA is approximately 1% and malaria transmission is high. Children were classified as normal (HbAA), heterozygous (HbAS), or homozygous (HbSS; SCA) for the rs334 A→T sickle mutation in HBB following batch-genotyping by PCR at the end of the trial. To avoid confounding from SCA-specific medical interventions, we considered children with an existing diagnosis of SCA (known SCA) separately from those diagnosed at the end of the trial (unknown SCA). The outcomes considered in this secondary analysis were measures of P falciparum parasite burden, features of severe malaria, and mortality at day 28 in malaria-positive children. FINDINGS Between Sept 17, 2014, and May 15, 2017, 3944 children with severe anaemia were enrolled into the TRACT trial. 3483 children from Uganda were considered in this secondary analysis. Overall, 1038 (30%) of 3483 Ugandan children had SCA. 1815 (78%) of 2321 children without SCA (HbAA) tested positive for P falciparum malaria, whereas the prevalence was significantly lower in children with SCA (347 [33%] of 1038; p<0·0001). Concentrations of plasma P falciparum histidine-rich protein 2 (PfHRP2), a marker of the total burden of malaria parasites within an individual, were significantly lower in children with either known SCA (median 8 ng/mL; IQR 0-57) or unknown SCA (7 ng/mL; 0-50) than in HbAA children (346 ng/mL; 21-2121; p<0·0001). In contrast to HbAA children, few HbSS children presented with classic features of severe and complicated malaria, but both the frequency and severity of anaemia were higher in HbSS children. We found no evidence for increased mortality at day 28 in those with SCA compared with those without SCA overall (hazard ratios 1·07 [95% CI 0·31-3·76] for known SCA and 0·67 [0·15-2·90] for unknown SCA). INTERPRETATION The current study suggests that children with SCA are innately protected against classic severe malaria. However, it also shows that even low-level infections can precipitate severe anaemic crises that would likely prove fatal without rapid access to blood transfusion services. FUNDING UK Medical Research Council, Wellcome, and UK National Institute for Health and Care Research.
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Affiliation(s)
- Sophie Uyoga
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Peter Olupot-Olupot
- Busitema University Faculty of Health Sciences, Mbale Regional Referral Hospital, Mbale, Uganda; Mbale Clinical Research Institute, Mbale, Uganda
| | - Roisin Connon
- Medical Research Council Clinical Trials Unit (MRC CTU) at University College London, London, UK
| | - Sarah Kiguli
- Department of Paediatrics and Child Health, School of Medicine, Makerere University, Kampala, Uganda
| | - Robert O Opoka
- Department of Paediatrics and Child Health, School of Medicine, Makerere University, Kampala, Uganda
| | | | - Rita Muhindo
- Mbale Clinical Research Institute, Mbale, Uganda
| | | | - Arjen M Dondorp
- Mahidol-Oxford Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Diana M Gibb
- Medical Research Council Clinical Trials Unit (MRC CTU) at University College London, London, UK
| | - A Sarah Walker
- Medical Research Council Clinical Trials Unit (MRC CTU) at University College London, London, UK
| | - Elizabeth C George
- Medical Research Council Clinical Trials Unit (MRC CTU) at University College London, London, UK
| | - Kathryn Maitland
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya; Department of Infectious Disease and Institute of Global Health Innovation, Division of Medicine, Imperial College London, London, UK
| | - Thomas N Williams
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya; Department of Infectious Disease and Institute of Global Health Innovation, Division of Medicine, Imperial College London, London, UK.
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MacCormick IJC, Zhang B, Hill D, Cordeiro MF, Small DS. A proposed theoretical framework for retinal biomarkers. ALZHEIMER'S & DEMENTIA (AMSTERDAM, NETHERLANDS) 2022; 14:e12327. [PMID: 35769873 PMCID: PMC9211063 DOI: 10.1002/dad2.12327] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 05/04/2022] [Accepted: 05/10/2022] [Indexed: 11/28/2022]
Abstract
Objective Propose a theoretical framework for retinal biomarkers of Alzheimer's disease (AD). Background The retina and brain share important biological features that are relevant to AD. Developing retinal biomarkers of AD is a strategic priority but as yet none have been validated for clinical use. Part of the reason may be that fundamental inferential assumptions have been overlooked. Failing to recognize these assumptions will disadvantage biomarker discovery and validation, but incorporating them into analyses could facilitate translation. New theory The biological assumption that a disease causes analogous effects in the brain and retina can be expressed within a Bayesian network. This allows inferences about abstract theory and individual events, and provides an opportunity to falsify the foundational hypothesis of retina-brain analogy. Graphical representation of the relationships between variables simplifies comparison between studies and facilitates judgements about whether key assumptions are valid given the current state of knowledge. Major challenges The framework provides a visual approach to retinal biomarkers and may help to rationalize analysis of future studies. It suggests possible reasons for inconsistent results in existing literature on AD biomarkers. Linkage to other theories The framework can be modified to describe alternative theories of retinal biomarker biology, such as retrograde degeneration resulting from brain disease, and can incorporate confounding factors such as co-existent glaucoma or macular degeneration. Parallels with analogue confirmation theory and surrogate marker validation suggest strengths and weaknesses of the framework that can be anticipated when developing analysis plans. Highlights Retinal biomarkers hold great promise for Alzheimer's disease (AD), but none are currently used clinically.Assumptions about the cause of retinal and brain changes are often overlooked, and this may disadvantage biomarker discovery and validation.We present a new approach to retinal biomarkers that describes cause and effect graphically in a Bayesian network.We show how this allows a more complete assessment of how well a biomarker might reflect the brain, and how data from right and left eyes can be used to rule out poor biomarker candidates.
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Affiliation(s)
- Ian James Callum MacCormick
- Centre for Inflammation ResearchUniversity of EdinburghThe Queen's Medical Research InstituteEdinburgh BioQuarterEdinburghUK
| | - Bo Zhang
- Wharton Department of Statistics and Data ScienceUniversity of PennsylvaniaPhiladelphiaPennsylvaniaUSA
| | - Daniel Hill
- Centre for Inflammation ResearchUniversity of EdinburghThe Queen's Medical Research InstituteEdinburgh BioQuarterEdinburghUK
- UCL Institute of OphthalmologyLondonUK
| | - Maria Francesca Cordeiro
- UCL Institute of OphthalmologyLondonUK
- Western Eye Hospital Imperial College Healthcare NHS TrustLondonUK
- ICORGImperial CollegeLondonUK
| | - Dylan S. Small
- Wharton Department of Statistics and Data ScienceUniversity of PennsylvaniaPhiladelphiaPennsylvaniaUSA
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10
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Keswani T, Obeidallah A, Nieves E, Sidoli S, Fazzari M, Taylor T, Seydel K, Daily JP. Pipecolic Acid, a Putative Mediator of the Encephalopathy of Cerebral Malaria and the Experimental Model of Cerebral Malaria. J Infect Dis 2022; 225:705-714. [PMID: 34932816 PMCID: PMC8844588 DOI: 10.1093/infdis/jiab615] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Accepted: 12/20/2021] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND We explored a metabolic etiology of cerebral malaria (CM) coma. METHODS Plasma metabolites were compared between Malawian children with CM and mild Plasmodium falciparum malaria. A candidate molecule was further studied in animal models of malaria. RESULTS Clinically abnormal concentrations of pipecolic acid (PA) were present in CM plasma, and nearly normal in mild malaria samples. PA is renally cleared and the elevated PA blood levels were associated with renal insufficiency, which was present only in CM subjects. Prior studies demonstrate that PA has neuromodulatory effects and is generated by malaria parasites. PA brain levels in Plasmodium berghei ANKA-infected animals in the experimental cerebral malaria (ECM) model inversely correlated with normal behavior and correlated with blood-brain barrier (BBB) permeability. Mice infected with malaria species that do not induce neurological abnormalities or manifest BBB permeability had elevated plasma PA levels similar to ECM plasma at 7 days postinfection; however, they had low PA levels in the brain compared to ECM mice brains at 7 days postinfection. CONCLUSIONS Our model suggests that malaria-generated PA induces coma in CM and in ECM. The role of BBB permeability and the mechanisms of PA neuromodulation in CM will require additional investigation.
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Affiliation(s)
- Tarun Keswani
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, New York, USA
| | - Aisha Obeidallah
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, New York, USA
| | - Edward Nieves
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York, USA
| | - Simone Sidoli
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York, USA
| | - Melissa Fazzari
- Department of Epidemiology and Population Health, Albert Einstein College of Medicine, Bronx, New York, USA
| | - Terrie Taylor
- Blantyre Malaria Project, Kamuzu University of Health Sciences, Blantyre, Malawi
- Department of Osteopathic Medical Specialties, College of Osteopathic Medicine, Michigan State University, East Lansing, Michigan, USA
| | - Karl Seydel
- Blantyre Malaria Project, Kamuzu University of Health Sciences, Blantyre, Malawi
- Department of Osteopathic Medical Specialties, College of Osteopathic Medicine, Michigan State University, East Lansing, Michigan, USA
| | - Johanna P Daily
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, New York, USA
- Infectious Diseases, Department of Medicine, Albert Einstein College of Medicine, Bronx, New York, USA
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11
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Ortolan LS, Avril M, Xue J, Seydel KB, Zheng Y, Smith JD. Plasmodium falciparum Parasite Lines Expressing DC8 and Group A PfEMP1 Bind to Brain, Intestinal, and Kidney Endothelial Cells. Front Cell Infect Microbiol 2022; 12:813011. [PMID: 35155278 PMCID: PMC8831842 DOI: 10.3389/fcimb.2022.813011] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Accepted: 01/10/2022] [Indexed: 11/13/2022] Open
Abstract
Cytoadhesion of Plasmodium falciparum-infected red blood cells is a virulence determinant associated with microvascular obstruction and organ complications. The gastrointestinal tract is a major site of sequestration in fatal cerebral malaria cases and kidney complications are common in severe malaria, but parasite interactions with these microvascular sites are poorly characterized. To study parasite tropism for different microvascular sites, we investigated binding of parasite lines to primary human microvascular endothelial cells from intestine (HIMEC) and peritubular kidney (HKMEC) sites. Of the three major host receptors for P. falciparum, CD36 had low or negligible expression; endothelial protein C receptor (EPCR) had the broadest constitutive expression; and intercellular adhesion molecule 1 (ICAM-1) was weakly expressed on resting cells and was strongly upregulated by TNF-α on primary endothelial cells from the brain, intestine, and peritubular kidney sites. By studying parasite lines expressing var genes linked to severe malaria, we provide evidence that both the DC8 and Group A EPCR-binding subsets of the P. falciparum erythrocyte membrane protein 1 (PfEMP1) family encodes binding affinity for brain, intestinal, and peritubular kidney endothelial cells, and that DC8 parasite adhesion was partially dependent on EPCR. Collectively, these findings raise the possibility of a brain-gut-kidney binding axis contributing to multi-organ complications in severe malaria.
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Affiliation(s)
- Luana S. Ortolan
- Center for Global Infectious Disease Research, Seattle Children’s Research Institute, Seattle, WA, United States
| | - Marion Avril
- Center for Global Infectious Disease Research, Seattle Children’s Research Institute, Seattle, WA, United States
| | - Jun Xue
- Department of Bioengineering, University of Washington, Seattle, WA, United States
| | - Karl B. Seydel
- Department of Osteopathic Medical Specialties, College of Osteopathic Medicine, Michigan State University, East Lansing, MI, United States
- Blantyre Malaria Project, Kamuzu University of Health Sciences, Blantyre, Malawi
| | - Ying Zheng
- Department of Bioengineering, University of Washington, Seattle, WA, United States
| | - Joseph D. Smith
- Center for Global Infectious Disease Research, Seattle Children’s Research Institute, Seattle, WA, United States
- Department of Pediatrics, University of Washington, Seattle, WA, United States
- *Correspondence: Joseph D. Smith,
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12
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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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13
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Sahu PK, Duffy FJ, Dankwa S, Vishnyakova M, Majhi M, Pirpamer L, Vigdorovich V, Bage J, Maharana S, Mandala W, Rogerson SJ, Seydel KB, Taylor TE, Kim K, Sather DN, Mohanty A, Mohanty RR, Mohanty A, Pattnaik R, Aitchison JD, Hoffman A, Mohanty S, Smith JD, Bernabeu M, Wassmer SC. Determinants of brain swelling in pediatric and adult cerebral malaria. JCI Insight 2021; 6:145823. [PMID: 34549725 PMCID: PMC8492338 DOI: 10.1172/jci.insight.145823] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Accepted: 07/28/2021] [Indexed: 01/08/2023] Open
Abstract
Cerebral malaria (CM) affects children and adults, but brain swelling is more severe in children. To investigate features associated with brain swelling in malaria, we performed blood profiling and brain MRI in a cohort of pediatric and adult patients with CM in Rourkela, India, and compared them with an African pediatric CM cohort in Malawi. We determined that higher plasma Plasmodium falciparum histidine rich protein 2 (PfHRP2) levels and elevated var transcripts that encode for binding to endothelial protein C receptor (EPCR) were linked to CM at both sites. Machine learning models trained on the African pediatric cohort could classify brain swelling in Indian children CM cases but had weaker performance for adult classification, due to overall lower parasite var transcript levels in this age group and more severe thrombocytopenia in Rourkela adults. Subgrouping of patients with CM revealed higher parasite biomass linked to severe thrombocytopenia and higher Group A–EPCR var transcripts in mild thrombocytopenia. Overall, these findings provide evidence that higher parasite biomass and a subset of Group A–EPCR binding variants are common features in children and adult CM cases, despite age differences in brain swelling.
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Affiliation(s)
- Praveen K Sahu
- Center for the Study of Complex Malaria in India, Ispat General Hospital (IGH), Rourkela, Odisha, India
| | - Fergal J Duffy
- Seattle Children's Research Institute, Seattle, Washington, USA
| | - Selasi Dankwa
- Seattle Children's Research Institute, Seattle, Washington, USA
| | | | | | - Lukas Pirpamer
- Department of Infection Biology, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | | | - Jabamani Bage
- Center for the Study of Complex Malaria in India, Ispat General Hospital (IGH), Rourkela, Odisha, India
| | - Sameer Maharana
- Center for the Study of Complex Malaria in India, Ispat General Hospital (IGH), Rourkela, Odisha, India
| | - Wilson Mandala
- Malawi University of Science and Technology, Limbe, Malawi
| | - Stephen J Rogerson
- Department of Medicine, The Doherty Institute, University of Melbourne, Melbourne, Australia
| | - Karl B Seydel
- Department of Osteopathic Medical Specialties, College of Osteopathic Medicine, Michigan State University, East Lansing, Michigan, USA.,Blantyre Malaria Project, Kamuzu University of Health Sciences, Blantyre, Malawi
| | - Terrie E Taylor
- Department of Osteopathic Medical Specialties, College of Osteopathic Medicine, Michigan State University, East Lansing, Michigan, USA.,Blantyre Malaria Project, Kamuzu University of Health Sciences, Blantyre, Malawi
| | - Kami Kim
- Division of Infectious Diseases and International Medicine, Morsani College of Medicine, University of South Florida, Tampa, Florida, USA
| | - D Noah Sather
- Seattle Children's Research Institute, Seattle, Washington, USA.,Department of Pediatrics, University of Washington, Seattle, Washington, USA
| | - Akshaya Mohanty
- Infectious Diseases Biology Unit, Institute of Life Sciences, Bhubaneswar, Odisha, India
| | | | - Anita Mohanty
- Department of Intensive Care, IGH, Rourkela, Odisha, India
| | | | - John D Aitchison
- Seattle Children's Research Institute, Seattle, Washington, USA.,Department of Pediatrics, University of Washington, Seattle, Washington, USA
| | - Angelika Hoffman
- Department of Neuroradiology, University Hospital Heidelberg, Heidelberg, Germany.,University Institute of Diagnostic and Interventional Neuroradiology, University Hospital Bern, Inselspital, University of Bern, Switzerland
| | - Sanjib Mohanty
- Center for the Study of Complex Malaria in India, Ispat General Hospital (IGH), Rourkela, Odisha, India
| | - Joseph D Smith
- Seattle Children's Research Institute, Seattle, Washington, USA.,Department of Pediatrics, University of Washington, Seattle, Washington, USA
| | - Maria Bernabeu
- Seattle Children's Research Institute, Seattle, Washington, USA.,European Molecular Biology Laboratory (EMBL), Barcelona, Spain
| | - Samuel C Wassmer
- Department of Infection Biology, London School of Hygiene & Tropical Medicine, London, United Kingdom
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14
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Bahmani T, Karimi A, Rezaei N, Daliri S. Retinopathy prematurity: a systematic review and meta-analysis study based on neonatal and maternal risk factors. J Matern Fetal Neonatal Med 2021; 35:8032-8050. [PMID: 34256661 DOI: 10.1080/14767058.2021.1940938] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
BACKGROUND Retinopathy of prematurity is the abnormal development of retinal arteries in preterm neonates less than 32 weeks and weighing 1500 g, and less, which can lead to visual impairment during life and blindness. This study aims to investigate the relationship between some clinical characteristics of neonates and mothers with Retinopathy of prematurity in the world via a systematic review and meta-analysis. MATERIALS AND METHODS The present study is a systematic review and meta-analysis on the relationship between maternal and neonatal clinical variables with Retinopathy of prematurity in the world from the beginning of 2000 to the end of 2020. Accordingly, all English articles published on the topic were searched in scientific databases of Web of Science, PubMed, Google Scholar, Science Direct, and Scopus. The articles were searched independently by two researchers. Statistical analysis of data was performed using fixed and random effects model statistical tests in the meta-analysis, Cochran, meta-regression, I2 index, Funnel plot, and Begg's by STATA software program, version 14. RESULT A total of 191 studies with a sample size of 140,921 persons were including in the meta-analysis. Accordingly, Preterm delivery ≤28 weeks (OR:6.3, 95% CI:4.9-8.1), Birth Weight ≤1000 g (OR:5.8, 95% CI:4.8-6.8), Birth Weight ≤1500 g (OR:4.8, 95% CI:3.8-6.1), PROM (OR:1.2, 95% CI:1.0-1.4), induced fertility (OR:1.9, 95% CI:1.1-3.0) and Chorioamnionitis (OR:1.5, 95% CI:1.0-2.2) There was a statistically significant association with retinopathy. CONCLUSION Based on the results of the present meta-analysis, the risk of retinopathy of prematurity in neonates born at 28 weeks and less, LBW (weight 1500 g and less), neonatal hypotension, chorioamnionitis, and induced fertility increases.
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Affiliation(s)
- Tahereh Bahmani
- School Medicine, Ilam University of Medical Science, Ilam, Iran
| | - Arezoo Karimi
- Department of Epidemiology, School of Public Health, Shahroud University of Medical Sciences, Shahroud, Iran
| | - Nazanin Rezaei
- Department of Midwifery, Faculty of Nursing and Midwifery, Ilam University of Medical Sciences, Ilam, Iran
| | - Salman Daliri
- Clinical Research Development Unit, Imam Hossein Hospital, Shahroud University of Medical Sciences, Shahroud, Iran
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15
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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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16
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Uyoga S, Wanjiku P, Rop JC, Makale J, Macharia AW, Nyutu GM, Shebe M, Awuondo KA, Mturi N, Woodrow CJ, Dondorp AM, Maitland K, Williams TN. Plasma Plasmodium falciparum Histidine-Rich Protein-2 concentrations in children with malaria infections of differing severity in Kilifi, Kenya. Clin Infect Dis 2020; 73:e2415-e2423. [PMID: 32772115 PMCID: PMC8492128 DOI: 10.1093/cid/ciaa1141] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Indexed: 11/13/2022] Open
Abstract
Background Most previous studies support a direct link between total parasite load and the clinical severity of Plasmodium falciparum malaria infections. Methods We estimated P. falciparum parasite loads in 3 groups of children with malaria infections of differing severity: (1) children with World Health Organization–defined severe malaria (n = 1544), (2) children admitted with malaria but without features of severity (n = 200), and (3) children in the community with asymptomatic parasitemia (n = 33). Results Peripheral parasitemias were highest in those with uncomplicated malaria (geometric mean [GM] parasite count, 111 064/μL; 95% confidence interval, CI, 86 798–141 819/μL), almost 3 times higher than in those with severe malaria (39 588/μL; 34 990–44 791/μL) and >100 times higher than in those with asymptomatic malaria (1092/μL; 523–2280/μL). However, the GM P. falciparum histidine-rich protein 2 (PfHRP2) values (95% CI) increased with severity, being 7 (4–12) ng/mL in asymptomatic malaria, 843 (655–1084) ng/mL in uncomplicated malaria, and 1369 (1244–1506) ng/mL in severe malaria. PfHRP2 concentrations were markedly lower in the subgroup of patients with severe malaria and concomitant invasive bacterial infections of blood or cerebrospinal fluid (GM concentration, 312 ng/mL; 95% CI, 175–557 ng/mL; P < .001) than in those without such infections (1439 ng/mL; 1307–1584; P < .001). Conclusions The clinical severity of malaria infections related strongly to the total burden of P. falciparum parasites. A quantitative test for plasma concentrations of PfHRP2 could be useful in identifying children at the greatest clinical risk and identifying critically ill children in whom malaria is not the primary cause.
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Affiliation(s)
- Sophie Uyoga
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | | | - Jesse C Rop
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | | | | | | | | | | | - Neema Mturi
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Charles J Woodrow
- 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, UK
| | - Arjen M Dondorp
- 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, UK
| | - Kathryn Maitland
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya.,Department of Infectious Diseases, Imperial College, London, UK
| | - Thomas N Williams
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya.,Department of Infectious Diseases, Imperial College, London, UK
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17
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Varo R, Erice C, Johnson S, Bassat Q, Kain KC. Clinical trials to assess adjuvant therapeutics for severe malaria. Malar J 2020; 19:268. [PMID: 32709257 PMCID: PMC7382078 DOI: 10.1186/s12936-020-03340-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Accepted: 07/17/2020] [Indexed: 01/07/2023] Open
Abstract
Despite potent anti-malarial treatment, mortality rates associated with severe falciparum malaria remain high. To attempt to improve outcome, several trials have assessed a variety of potential adjunctive therapeutics, however none to date has been shown to be beneficial. This may be due, at least partly, to the therapeutics chosen and clinical trial design used. Here, we highlight three themes that could facilitate the choice and evaluation of putative adjuvant interventions for severe malaria, paving the way for their assessment in randomized controlled trials. Most clinical trials of adjunctive therapeutics to date have been underpowered due to the large number of participants required to reach mortality endpoints, rendering these study designs challenging and expensive to conduct. These limitations may be mitigated by the use of risk-stratification of participants and application of surrogate endpoints. Appropriate surrogate endpoints include direct measures of pathways causally involved in the pathobiology of severe and fatal malaria, including markers of host immune and endothelial activation and microcirculatory dysfunction. We propose using circulating markers of these pathways to identify high-risk participants that would be most likely to benefit from adjunctive therapy, and further by adopting these biomarkers as surrogate endpoints; moreover, choosing interventions that target deleterious host immune responses that directly contribute to microcirculatory dysfunction, multi-organ dysfunction and death; and, finally, prioritizing where possible, drugs that act on these pathways that are already approved by the FDA, or other regulators, for other indications, and are known to be safe in target populations, including children. An emerging understanding of the critical role of the host response in severe malaria pathogenesis may facilitate both clinical trial design and the search of effective adjunctive therapeutics.
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Affiliation(s)
- Rosauro Varo
- ISGlobal, Barcelona Institute for Global Health, Hospital Clínic, Universitat de Barcelona, Barcelona, Spain.,Centro de Investigação em Saúde de Manhiça, Manhiça, Mozambique
| | - Clara Erice
- Sandra-Rotman Centre for Global Health, Toronto General Research Institute, University Health Network-Toronto General Hospital, Toronto, ON, Canada
| | | | - Quique Bassat
- ISGlobal, Barcelona Institute for Global Health, Hospital Clínic, Universitat de Barcelona, Barcelona, Spain.,Centro de Investigação em Saúde de Manhiça, Manhiça, Mozambique.,ICREA, Pg. Lluís Companys 23, 08010, Barcelona, Spain.,Pediatric Infectious Diseases Unit, Pediatrics Department, Hospital Sant Joan de Déu (University of Barcelona), Barcelona, Spain.,Consorcio de Investigación Biomédica en Red de Epidemiología y Salud Pública (CIBERESP), Madrid, Spain
| | - Kevin C Kain
- Sandra-Rotman Centre for Global Health, Toronto General Research Institute, University Health Network-Toronto General Hospital, Toronto, ON, Canada. .,Department of Medicine, Division of Infectious Diseases, Tropical Disease Unit, University of Toronto, Toronto, Canada.
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18
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Akech S, Chepkirui M, Ogero M, Agweyu A, Irimu G, English M, Snow RW. The Clinical Profile of Severe Pediatric Malaria in an Area Targeted for Routine RTS,S/AS01 Malaria Vaccination in Western Kenya. Clin Infect Dis 2020; 71:372-380. [PMID: 31504308 PMCID: PMC7353324 DOI: 10.1093/cid/ciz844] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2019] [Accepted: 08/23/2019] [Indexed: 01/05/2023] Open
Abstract
BACKGROUND The malaria prevalence has declined in western Kenya, resulting in the risk of neurological phenotypes in older children. This study investigates the clinical profile of pediatric malaria admissions ahead of the introduction of the RTS,S/AS01 vaccine. METHODS Malaria admissions in children aged 1 month to 15 years were identified from routine, standardized, inpatient clinical surveillance data collected between 2015 and 2018 from 4 hospitals in western Kenya. Malaria phenotypes were defined based on available data. RESULTS There were 5766 malaria admissions documented. The median age was 36 months (interquartile range, 18-60): 15% were aged between 1-11 months of age, 33% were aged 1-23 months of age, and 70% were aged 1 month to 5 years. At admission, 2340 (40.6%) children had severe malaria: 421/2208 (19.1%) had impaired consciousness, 665/2240 (29.7%) had an inability to drink or breastfeed, 317/2340 (13.6%) had experienced 2 or more convulsions, 1057/2340 (45.2%) had severe anemia, and 441/2239 (19.7%) had severe respiratory distress. Overall, 211 (3.7%) children admitted with malaria died; 163/211 (77% deaths, case fatality rate 7.0%) and 48/211 (23% deaths, case fatality rate 1.4%) met the criteria for severe malaria and nonsevere malaria at admission, respectively. The median age for fatal cases was 33 months (interquartile range, 12-72) and the case fatality rate was highest in those unconscious (44.4%). CONCLUSIONS Severe malaria in western Kenya is still predominantly seen among the younger pediatric age group and current interventions targeted for those <5 years are appropriate. However, there are increasing numbers of children older than 5 years admitted with malaria, and ongoing hospital surveillance would identify when interventions should target older children.
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Affiliation(s)
- Samuel Akech
- Kenya Medical Research Institute/Wellcome Trust Research Programme, Nairobi, Kenya
| | - Mercy Chepkirui
- Kenya Medical Research Institute/Wellcome Trust Research Programme, Nairobi, Kenya
| | - Morris Ogero
- Kenya Medical Research Institute/Wellcome Trust Research Programme, Nairobi, Kenya
| | - Ambrose Agweyu
- Kenya Medical Research Institute/Wellcome Trust Research Programme, Nairobi, Kenya
| | - Grace Irimu
- Kenya Medical Research Institute/Wellcome Trust Research Programme, Nairobi, Kenya
- Department of Paediatrics and Child Health, University of Nairobi, Nairobi, Kenya
| | - Mike English
- Kenya Medical Research Institute/Wellcome Trust Research Programme, Nairobi, Kenya
- Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, United Kingdom
| | - Robert W Snow
- Kenya Medical Research Institute/Wellcome Trust Research Programme, Nairobi, Kenya
- Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, United Kingdom
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19
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Vera IM, Kessler A, Ting LM, Harawa V, Keller T, Allen D, Njie M, Moss M, Soko M, Ahmadu A, Kadwala I, Ray S, Nyirenda TS, Mandala WL, Taylor TE, Rogerson SJ, Seydel KB, Kim K. Plasma cell-free DNA predicts pediatric cerebral malaria severity. JCI Insight 2020; 5:136279. [PMID: 32554925 DOI: 10.1172/jci.insight.136279] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Accepted: 05/20/2020] [Indexed: 12/28/2022] Open
Abstract
BACKGROUNDPrediction of adverse outcomes in cerebral malaria (CM) is difficult. We hypothesized that cell-free DNA (cfDNA) levels would facilitate identification of severe and potentially fatal CM cases.METHODSIn this retrospective study, plasma from Malawian children with CM (n = 134), uncomplicated malaria (UM, n = 77), and healthy controls (HC, n = 60) was assayed for cfDNA using a fluorescence assay. Host and parasite cfDNA was measured by quantitative PCR. Immune markers were determined by ELISA, Luminex, or cytometric bead array.RESULTSTotal cfDNA increased with malaria severity (HC versus UM, P < 0.001; HC versus CM, P < 0.0001; UM versus CM, P < 0.0001), was elevated in retinopathy-positive (Ret+) CM relative to Ret- CM (7.66 versus 5.47 ng/μL, P = 0.027), and differentiated Ret+ fatal cases from survivors (AUC 0.779; P < 0.001). cfDNA levels in patients with non-malarial febrile illness (NMF, P = 0.25) and non-malarial coma (NMC, P = 0.99) were comparable with UM. Host DNA, rather than parasite DNA, was the major cfDNA contributor (UM, 268 versus 67 pg/μL; CM, 2824 versus 463 pg/μL). Host and parasite cfDNA distinguished CM by retinopathy (host, AUC 0.715, P = 0.0001; parasite, AUC 0.745, P = 0.0001), but only host cfDNA distinguished fatal cases (AUC 0.715, P = 0.0001). Total cfDNA correlated with neutrophil markers IL-8 (rs = 0.433, P < 0.0001) and myeloperoxidase (rs = 0.683, P < 0.0001).CONCLUSIONQuantifying plasma cfDNA is a simple assay useful in identifying children at risk for fatal outcome and has promise as a point-of-care assay. Elevated cfDNA suggests a link with host inflammatory pathways in fatal CM.FUNDINGNIH NCATS (AK), Burroughs-Wellcome (AK), and National Health and Medical Research Council of Australia (SJR).
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Affiliation(s)
- Iset Medina Vera
- Morsani College of Medicine, University of South Florida, Tampa, Florida, USA
| | - Anne Kessler
- Albert Einstein College of Medicine, Bronx, New York, USA
| | - Li-Min Ting
- Morsani College of Medicine, University of South Florida, Tampa, Florida, USA.,Albert Einstein College of Medicine, Bronx, New York, USA
| | - Visopo Harawa
- Blantyre Malaria Project, University of Malawi College of Medicine, Blantyre, Malawi
| | - Thomas Keller
- Morsani College of Medicine, University of South Florida, Tampa, Florida, USA
| | - Dylan Allen
- Morsani College of Medicine, University of South Florida, Tampa, Florida, USA
| | - Madi Njie
- Department of Medicine, University of Melbourne, Melbourne, Victoria, Australia
| | - McKenze Moss
- Xavier University of Louisiana, New Orleans, Louisiana, USA
| | - Monica Soko
- College of Medicine, University of Malawi, Blantyre, Malawi
| | - Ajisa Ahmadu
- Malawi-Liverpool Wellcome Trust Clinical Research Programme, Blantyre, Malawi
| | | | - Stephen Ray
- Blantyre Malaria Project, University of Malawi College of Medicine, Blantyre, Malawi.,Malawi-Liverpool Wellcome Trust Clinical Research Programme, Blantyre, Malawi
| | - Tonney S Nyirenda
- College of Medicine, University of Malawi, Blantyre, Malawi.,Malawi-Liverpool Wellcome Trust Clinical Research Programme, Blantyre, Malawi
| | - Wilson L Mandala
- Malawi-Liverpool Wellcome Trust Clinical Research Programme, Blantyre, Malawi.,Malawi University of Science and Technology, Thyolo, Malawi
| | - Terrie E Taylor
- Blantyre Malaria Project, University of Malawi College of Medicine, Blantyre, Malawi.,College of Osteopathic Medicine, Michigan State University, East Lansing, Michigan, USA
| | - Stephen J Rogerson
- Department of Medicine, University of Melbourne, Melbourne, Victoria, Australia
| | - Karl B Seydel
- Blantyre Malaria Project, University of Malawi College of Medicine, Blantyre, Malawi.,College of Osteopathic Medicine, Michigan State University, East Lansing, Michigan, USA
| | - Kami Kim
- Morsani College of Medicine, University of South Florida, Tampa, Florida, USA.,Albert Einstein College of Medicine, Bronx, New York, USA
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20
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HRP2: Transforming Malaria Diagnosis, but with Caveats. Trends Parasitol 2020; 36:112-126. [DOI: 10.1016/j.pt.2019.12.004] [Citation(s) in RCA: 57] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Revised: 11/29/2019] [Accepted: 12/02/2019] [Indexed: 11/23/2022]
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21
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Jensen AR, Adams Y, Hviid L. Cerebral Plasmodium falciparum malaria: The role of PfEMP1 in its pathogenesis and immunity, and PfEMP1-based vaccines to prevent it. Immunol Rev 2020; 293:230-252. [PMID: 31562653 PMCID: PMC6972667 DOI: 10.1111/imr.12807] [Citation(s) in RCA: 81] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Revised: 09/04/2019] [Accepted: 09/09/2019] [Indexed: 12/13/2022]
Abstract
Malaria, a mosquito-borne infectious disease caused by parasites of the genus Plasmodium continues to be a major health problem worldwide. The unicellular Plasmodium-parasites have the unique capacity to infect and replicate within host erythrocytes. By expressing variant surface antigens Plasmodium falciparum has evolved to avoid protective immune responses; as a result in endemic areas anti-malaria immunity develops gradually over many years of multiple and repeated infections. We are studying the role of Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) expressed by asexual stages of P. falciparum responsible for the pathogenicity of severe malaria. The immunopathology of falciparum malaria has been linked to cyto-adhesion of infected erythrocytes to specific host receptors. A greater appreciation of the PfEMP1 molecules important for the development of protective immunity and immunopathology is a prerequisite for the rational discovery and development of a safe and protective anti-disease malaria vaccine. Here we review the role of ICAM-1 and EPCR receptor adhering falciparum-parasites in the development of severe malaria; we discuss our current research to understand the factors involved in the pathogenesis of cerebral malaria and the feasibility of developing a vaccine targeted specifically to prevent this disease.
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Affiliation(s)
- Anja Ramstedt Jensen
- Centre for Medical Parasitology at Department of Immunology and MicrobiologyFaculty of Health and Medical SciencesUniversity of CopenhagenCopenhagenDenmark
| | - Yvonne Adams
- Centre for Medical Parasitology at Department of Immunology and MicrobiologyFaculty of Health and Medical SciencesUniversity of CopenhagenCopenhagenDenmark
| | - Lars Hviid
- Centre for Medical Parasitology at Department of Immunology and MicrobiologyFaculty of Health and Medical SciencesUniversity of CopenhagenCopenhagenDenmark
- Department of Infectious DiseasesRigshospitaletCopenhagenDenmark
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22
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Meta-analysis of Plasmodium falciparum var Signatures Contributing to Severe Malaria in African Children and Indian Adults. mBio 2019; 10:mBio.00217-19. [PMID: 31040236 PMCID: PMC6495371 DOI: 10.1128/mbio.00217-19] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
The clinical presentation of severe Plasmodium falciparum malaria differs between children and adults, but the mechanistic basis for this remains unclear. Contributing factors to disease severity include total parasite biomass and the diverse cytoadhesive properties mediated by the polymorphic var gene parasite ligand family displayed on infected erythrocytes. To explore these factors, we performed a multicohort analysis of the contribution of var expression and parasite biomass to severe malaria in two previously published pediatric cohorts in Tanzania and Malawi and an adult cohort in India. Machine learning analysis revealed independent and complementary roles for var adhesion types and parasite biomass in adult and pediatric severe malaria and showed that similar var profiles, including upregulation of group A and DC8 var, predict severe malaria in adults and children. Among adults, patients with multiorgan complications presented infections with significantly higher parasite biomass without significant differences in var adhesion types. Conversely, pediatric patients with specific complications showed distinct var signatures. Cerebral malaria patients showed broadly increased expression of var genes, in particular group A and DC8 var, while children with severe malaria anemia were classified based on high transcription of DC8 var only. This study represents the first large multisite meta-analysis of var expression, and it demonstrates the presence of common var profiles in severe malaria patients of different ages across distant geographical sites, as well as syndrome-specific disease signatures. The complex associations between parasite biomass, var adhesion type, and clinical presentation revealed here represent the most comprehensive picture so far of the relationship between cytoadhesion, parasite load, and clinical syndrome.IMPORTANCE P. falciparum malaria can cause multiple disease complications that differ by patient age. Previous studies have attempted to address the roles of parasite adhesion and biomass in disease severity; however, these studies have been limited to single geographical sites, and there is limited understanding of how parasite adhesion and biomass interact to influence disease manifestations. In this meta-analysis, we compared parasite disease determinants in African children and Indian adults. This study demonstrates that parasite biomass and specific subsets of var genes are independently associated with detrimental outcomes in both childhood and adult malaria. We also explored how parasite var adhesion types and biomass play different roles in the development of specific severe malaria pathologies, including childhood cerebral malaria and multiorgan complications in adults. This work represents the largest study to date of the role of both var adhesion types and biomass in severe malaria.
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23
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Dutta G, Lillehoj PB. Wash-free, label-free immunoassay for rapid electrochemical detection of PfHRP2 in whole blood samples. Sci Rep 2018; 8:17129. [PMID: 30459336 PMCID: PMC6244414 DOI: 10.1038/s41598-018-35471-8] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2018] [Accepted: 11/05/2018] [Indexed: 02/06/2023] Open
Abstract
Currently, the diagnosis of many diseases relies on laboratory-based immunoassays (ELISA, Western Blot), which are laborious, time-consuming and expensive. To address these limitations, we report a wash-free and label-free electrochemical immunoassay for rapid measurements of protein biomarkers in blood samples. This immunosensor employs a unique detection scheme based on electrochemical-chemical (EC) redox cycling for signal amplification combined with an affinity-based protein quantification strategy. All of the reagents required for this assay are dried and stored on a stacked membrane assembly, consisting of a Vivid Plasma Separation membrane and two cellulose membranes situated above the sensor, enabling excellent stability at room temperature for up to 2 months. Proof of concept was carried out by performing measurements of Plasmodium falciparum histidine-rich protein 2 (PfHRP2) in whole blood samples, which could be detected from 100 ng/mL to 100 µg/mL with excellent specificity and reproducibility. Each measurement requires only two liquid dispensing steps and can completed in 5 min, making this diagnostic platform promising for point-of-care testing in resource-limited settings.
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Affiliation(s)
- Gorachand Dutta
- Department of Electronic and Electrical Engineering, University of Bath, Claverton Down, Bath, BA2 7AY, UK.,Centre for Biosensors, Bioelectronics and Biodevices, University of Bath, Claverton Down, Bath, BA2 7AY, UK
| | - Peter B Lillehoj
- Department of Mechanical Engineering, Michigan State University, East Lansing, MI, 48824, USA. .,Department of Biomedical Engineering, Michigan State University, East Lansing, MI, 48824, USA.
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24
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Glennon EKK, Dankwa S, Smith JD, Kaushansky A. Opportunities for Host-targeted Therapies for Malaria. Trends Parasitol 2018; 34:843-860. [PMID: 30122551 PMCID: PMC6168423 DOI: 10.1016/j.pt.2018.07.011] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Revised: 07/20/2018] [Accepted: 07/23/2018] [Indexed: 12/19/2022]
Abstract
Despite the recent successes of artemisinin-based antimalarial drugs, many still die from severe malaria, and eradication efforts are hindered by the limited drugs currently available to target transmissible gametocyte parasites and liver-resident dormant Plasmodium vivax hypnozoites. Host-targeted therapy is a new direction for infectious disease drug development and aims to interfere with host molecules, pathways, or networks that are required for infection or that contribute to disease. Recent advances in our understanding of host pathways involved in parasite development and pathogenic mechanisms in severe malaria could facilitate the development of host-targeted interventions against Plasmodium infection and malaria disease. This review discusses new opportunities for host-targeted therapeutics for malaria and the potential to harness drug polypharmacology to simultaneously target multiple host pathways using a single drug intervention.
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Affiliation(s)
- Elizabeth K K Glennon
- Center for Infectious Disease Research, 307 Westlake Ave N Suite 500, Seattle, WA 98109, USA; Department of Global Health, University of Washington, Harris Hydraulics Laboratory, Box 357965, Seattle, WA 98195, USA; These authors made an equal contribution
| | - Selasi Dankwa
- Center for Infectious Disease Research, 307 Westlake Ave N Suite 500, Seattle, WA 98109, USA; These authors made an equal contribution
| | - Joseph D Smith
- Center for Infectious Disease Research, 307 Westlake Ave N Suite 500, Seattle, WA 98109, USA; Department of Global Health, University of Washington, Harris Hydraulics Laboratory, Box 357965, Seattle, WA 98195, USA
| | - Alexis Kaushansky
- Center for Infectious Disease Research, 307 Westlake Ave N Suite 500, Seattle, WA 98109, USA; Department of Global Health, University of Washington, Harris Hydraulics Laboratory, Box 357965, Seattle, WA 98195, USA.
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25
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Kessler A, Campo JJ, Harawa V, Mandala WL, Rogerson SJ, Mowrey WB, Seydel KB, Kim K. Convalescent Plasmodium falciparum-specific seroreactivity does not correlate with paediatric malaria severity or Plasmodium antigen exposure. Malar J 2018; 17:178. [PMID: 29695240 PMCID: PMC5918990 DOI: 10.1186/s12936-018-2323-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2017] [Accepted: 04/18/2018] [Indexed: 12/17/2022] Open
Abstract
Background Antibody immunity is thought to be essential to prevent severe Plasmodium falciparum infection, but the exact correlates of protection are unknown. Over time, children in endemic areas acquire non-sterile immunity to malaria that correlates with development of antibodies to merozoite invasion proteins and parasite proteins expressed on the surface of infected erythrocytes. Results A 1000 feature P. falciparum 3D7 protein microarray was used to compare P. falciparum-specific seroreactivity during acute infection and 30 days after infection in 23 children with uncomplicated malaria (UM) and 25 children with retinopathy-positive cerebral malaria (CM). All children had broad P. falciparum antibody reactivity during acute disease. IgM reactivity decreased and IgG reactivity increased in convalescence. Antibody reactivity to CIDR domains of “virulent” PfEMP1 proteins was low with robust reactivity to the highly conserved, intracellular ATS domain of PfEMP1 in both groups. Although children with UM and CM differed markedly in parasite burden and PfEMP1 exposure during acute disease, neither acute nor convalescent PfEMP1 seroreactivity differed between groups. Greater seroprevalence to a conserved Group A-associated ICAM binding extracellular domain was observed relative to linked extracellular CIDRα1 domains in both case groups. Pooled immune IgG from Malawian adults revealed greater reactivity to PfEMP1 than observed in children. Conclusions Children with uncomplicated and cerebral malaria have similar breadth and magnitude of P. falciparum antibody reactivity. The utility of protein microarrays to measure serological recognition of polymorphic PfEMP1 antigens needs to be studied further, but the study findings support the hypothesis that conserved domains of PfEMP1 are more prominent targets of cross reactive antibodies than variable domains in children with symptomatic malaria. Protein microarrays represent an additional tool to identify cross-reactive Plasmodium antigens including PfEMP1 domains that can be investigated as strain-transcendent vaccine candidates. Electronic supplementary material The online version of this article (10.1186/s12936-018-2323-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Anne Kessler
- Albert Einstein College of Medicine, Bronx, NY, USA
| | | | - Visopo Harawa
- Malawi-Liverpool Wellcome Trust Clinical Research Programme, Blantyre, Malawi.,College of Medicine, Biomedical Department, University of Malawi, Blantyre, Malawi
| | - Wilson L Mandala
- Malawi-Liverpool Wellcome Trust Clinical Research Programme, Blantyre, Malawi.,College of Medicine, Biomedical Department, University of Malawi, Blantyre, Malawi.,Academy of Medical Sciences, Malawi University of Science and Technology, Thyolo, Malawi
| | | | | | - Karl B Seydel
- College of Osteopathic Medicine, Michigan State University, East Lansing, MI, USA. .,Blantyre Malaria Project, University of Malawi College of Medicine, Blantyre, Malawi.
| | - Kami Kim
- Albert Einstein College of Medicine, Bronx, NY, USA. .,Morsani College of Medicine, University of South Florida, Tampa, FL, USA.
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26
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Kessler A, Dankwa S, Bernabeu M, Harawa V, Danziger SA, Duffy F, Kampondeni SD, Potchen MJ, Dambrauskas N, Vigdorovich V, Oliver BG, Hochman SE, Mowrey WB, MacCormick IJC, Mandala WL, Rogerson SJ, Sather DN, Aitchison JD, Taylor TE, Seydel KB, Smith JD, Kim K. Linking EPCR-Binding PfEMP1 to Brain Swelling in Pediatric Cerebral Malaria. Cell Host Microbe 2017; 22:601-614.e5. [PMID: 29107642 DOI: 10.1016/j.chom.2017.09.009] [Citation(s) in RCA: 78] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2017] [Revised: 08/06/2017] [Accepted: 09/22/2017] [Indexed: 11/16/2022]
Abstract
Brain swelling is a major predictor of mortality in pediatric cerebral malaria (CM). However, the mechanisms leading to swelling remain poorly defined. Here, we combined neuroimaging, parasite transcript profiling, and laboratory blood profiles to develop machine-learning models of malarial retinopathy and brain swelling. We found that parasite var transcripts encoding endothelial protein C receptor (EPCR)-binding domains, in combination with high parasite biomass and low platelet levels, are strong indicators of CM cases with malarial retinopathy. Swelling cases presented low platelet levels and increased transcript abundance of parasite PfEMP1 DC8 and group A EPCR-binding domains. Remarkably, the dominant transcript in 50% of swelling cases encoded PfEMP1 group A CIDRα1.7 domains. Furthermore, a recombinant CIDRα1.7 domain from a pediatric CM brain autopsy inhibited the barrier-protective properties of EPCR in human brain endothelial cells in vitro. Together, these findings suggest a detrimental role for EPCR-binding CIDRα1 domains in brain swelling.
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Affiliation(s)
- Anne Kessler
- Department of Medicine, Albert Einstein College of Medicine and Montefiore Medical Center, Bronx, NY 10461, USA
| | - Selasi Dankwa
- Center for Infectious Disease Research, Seattle, WA 98109, USA
| | - Maria Bernabeu
- Center for Infectious Disease Research, Seattle, WA 98109, USA
| | - Visopo Harawa
- Malawi-Liverpool Wellcome Trust Clinical Research Programme, Blantyre BT3, Malawi; University of Malawi, College of Medicine, Biomedical Department, Blantyre BT3, Malawi
| | | | - Fergal Duffy
- Center for Infectious Disease Research, Seattle, WA 98109, USA
| | | | - Michael J Potchen
- Department of Imaging Sciences, University of Rochester, Rochester, NY 14642, USA
| | | | | | - Brian G Oliver
- Center for Infectious Disease Research, Seattle, WA 98109, USA
| | - Sarah E Hochman
- Department of Medicine, New York University Langone Health, New York, NY 10016, USA
| | - Wenzhu B Mowrey
- Department of Medicine, Albert Einstein College of Medicine and Montefiore Medical Center, Bronx, NY 10461, USA
| | - Ian J C MacCormick
- Malawi-Liverpool Wellcome Trust Clinical Research Programme, Blantyre BT3, Malawi; Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh EH16 4SB, UK; Department of Eye and Vision Sciences, University of Liverpool, Liverpool L69 3BX, UK
| | - Wilson L Mandala
- Malawi-Liverpool Wellcome Trust Clinical Research Programme, Blantyre BT3, Malawi; University of Malawi, College of Medicine, Biomedical Department, Blantyre BT3, Malawi; Academy of Medical Sciences, Malawi University of Science and Technology, Thyolo BT3, Malawi
| | - Stephen J Rogerson
- Department of Medicine at the Doherty Institute, The University of Melbourne, Melbourne, VIC 3000, Australia
| | - D Noah Sather
- Center for Infectious Disease Research, Seattle, WA 98109, USA
| | | | - Terrie E Taylor
- Blantyre Malaria Project, Blantyre BT3, Malawi; Department of Osteopathic Medical Specialities, College of Osteopathic Medicine, Michigan State University, East Lansing, MI 48824, USA
| | - Karl B Seydel
- Blantyre Malaria Project, Blantyre BT3, Malawi; Department of Osteopathic Medical Specialities, College of Osteopathic Medicine, Michigan State University, East Lansing, MI 48824, USA.
| | - Joseph D Smith
- Center for Infectious Disease Research, Seattle, WA 98109, USA; Department of Global Health, University of Washington, Seattle, WA 98195, USA.
| | - Kami Kim
- Department of Medicine, Albert Einstein College of Medicine and Montefiore Medical Center, Bronx, NY 10461, USA.
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27
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Shabani E, Hanisch B, Opoka RO, Lavstsen T, John CC. Plasmodium falciparum EPCR-binding PfEMP1 expression increases with malaria disease severity and is elevated in retinopathy negative cerebral malaria. BMC Med 2017; 15:183. [PMID: 29025399 PMCID: PMC5639490 DOI: 10.1186/s12916-017-0945-y] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/10/2017] [Accepted: 09/15/2017] [Indexed: 01/01/2023] Open
Abstract
BACKGROUND Expression of group A and the A-like subset of group B Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) is associated with severe malaria (SM). The diversity of var sequences combined with the challenges of distinct classification of patient pathologies has made studying the role of distinct PfEMP1 variants on malaria disease severity challenging. The application of retinopathy in the recent years has provided a further method to clinically evaluate children with cerebral malaria (CM). The question of whether children with clinical CM but no retinopathy represent a completely different disease process or a subgroup within the spectrum of CM remains an important question in malaria. In the current study, we use newly designed primer sets with the best coverage to date in a large cohort of children with SM to determine the role of var genes in malaria disease severity and especially CM as discriminated by retinopathy. METHODS We performed qRT-PCR targeting the different subsets of these var genes on samples from Ugandan children with CM (n = 98, of whom 50 had malarial retinopathy [RP] and 47 did not [RN]), severe malarial anemia (SMA, n = 47), and asymptomatic parasitemia (AP, n = 14). The primers used in this study were designed based on var sequences from 226 Illumina whole genome sequenced P. falciparum field isolates. RESULTS Increasing severity of illness was associated with increasing levels of endothelial protein C receptor (EPCR)-binding PfEMP1. EPCR-binding PfEMP1 transcript levels were highest in children with combined CM and SMA and then decreased by level of disease severity: RP CM > RN CM > SMA > AP. CONCLUSIONS The study findings indicate that PfEMP1 binding to EPCR is important in the pathogenesis of SM, including RN CM, and suggest that increased expression of EPCR-binding PfEMP1 is associated with progressively more severe disease. Agents that block EPCR-binding of PfEMP1 could provide novel interventions to prevent or decrease disease severity in malaria.
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Affiliation(s)
- Estela Shabani
- Ryan White Center for Pediatric Infectious Diseases and Global Health, Indiana University, 1044 W Walnut St R4 402D, Indianapolis, Indiana, USA.,Department of Pediatrics, Division of Global Pediatrics, University of Minnesota, Minneapolis, Minnesota, USA
| | | | - Robert O Opoka
- Department of Pediatrics and Child Health, Makerere University School of Medicine, Kampala, Uganda
| | - Thomas Lavstsen
- Centre for Medical Parasitology, Department of International Health, Immunology and Microbiology, University of Copenhagen and Department of Infectious Diseases, Copenhagen, Denmark
| | - Chandy C John
- Ryan White Center for Pediatric Infectious Diseases and Global Health, Indiana University, 1044 W Walnut St R4 402D, Indianapolis, Indiana, USA. .,Department of Pediatrics, Division of Global Pediatrics, University of Minnesota, Minneapolis, Minnesota, USA.
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28
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Njunge JM, Oyaro IN, Kibinge NK, Rono MK, Kariuki SM, Newton CR, Berkley JA, Gitau EN. Cerebrospinal fluid markers to distinguish bacterial meningitis from cerebral malaria in children. Wellcome Open Res 2017; 2:47. [PMID: 29181450 PMCID: PMC5686508 DOI: 10.12688/wellcomeopenres.11958.2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/11/2017] [Indexed: 12/23/2022] Open
Abstract
Background. Few hospitals in high malaria endemic countries in Africa have the diagnostic capacity for clinically distinguishing acute bacterial meningitis (ABM) from cerebral malaria (CM). As a result, empirical use of antibiotics is necessary. A biochemical marker of ABM would facilitate precise clinical diagnosis and management of these infections and enable rational use of antibiotics. Methods. We used label-free protein quantification by mass spectrometry to identify cerebrospinal fluid (CSF) markers that distinguish ABM (n=37) from CM (n=22) in Kenyan children. Fold change (FC) and false discovery rates (FDR) were used to identify differentially expressed proteins. Subsequently, potential biomarkers were assessed for their ability to discriminate between ABM and CM using receiver operating characteristic (ROC) curves. Results. The host CSF proteome response to ABM ( Haemophilusinfluenza and Streptococcuspneumoniae) is significantly different to CM. Fifty two proteins were differentially expressed (FDR<0.01, Log FC≥2), of which 83% (43/52) were upregulated in ABM compared to CM. Myeloperoxidase and lactotransferrin were present in 37 (100%) and 36 (97%) of ABM cases, respectively, but absent in CM (n=22). Area under the ROC curve (AUC), sensitivity, and specificity were assessed for myeloperoxidase (1, 1, and 1; 95% CI, 1-1) and lactotransferrin (0.98, 0.97, and 1; 95% CI, 0.96-1). Conclusion. Myeloperoxidase and lactotransferrin have a high potential to distinguish ABM from CM and thereby improve clinical management. Their validation requires a larger cohort of samples that includes other bacterial aetiologies of ABM.
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Affiliation(s)
- James M Njunge
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research Coast, Kilifi, Kenya
| | - Ian N Oyaro
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research Coast, Kilifi, Kenya.,University of Nairobi, Nairobi, Kenya
| | - Nelson K Kibinge
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research Coast, Kilifi, Kenya
| | - Martin K Rono
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research Coast, Kilifi, Kenya.,Pwani University Health and Research Institute, Pwani University, Kilifi, Kenya
| | - Symon M Kariuki
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research Coast, Kilifi, Kenya
| | - Charles R Newton
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research Coast, Kilifi, Kenya.,Department of Psychiatry, Medical Sciences Division, University of Oxford, Oxford, OX3 7JX, UK
| | - James A Berkley
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research Coast, Kilifi, Kenya.,Centre for Tropical Medicine and Global Health, University of Oxford, Oxford, OX3 7FZ, UK
| | - Evelyn N Gitau
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research Coast, Kilifi, Kenya.,Alliance for Accelerating Excellence in Science in Africa (AESA), Nairobi, Kenya
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29
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Park GS, Opoka RO, Shabani E, Wypyszynski A, Hanisch B, John CC. Plasmodium falciparum Histidine-Rich Protein-2 Plasma Concentrations Are Higher in Retinopathy-Negative Cerebral Malaria Than in Severe Malarial Anemia. Open Forum Infect Dis 2017; 4:ofx151. [PMID: 28948179 PMCID: PMC5597884 DOI: 10.1093/ofid/ofx151] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Accepted: 07/14/2017] [Indexed: 11/14/2022] Open
Abstract
Background Malaria retinopathy has been proposed as marker of “true” cerebral malaria (CM), ie, coma due to Plasmodium falciparum vs coma due to other causes, with incidental P falciparum parasitemia. Plasma P falciparum histidine-rich protein-2 (PfHRP2) concentrations distinguish retinopathy-positive (RP) from retinopathy-negative (RN) CM but have not been compared between RN CM and other forms of severe malaria or asymptomatic parasitemia (AP). Methods We compared plasma PfHRP2 concentrations in 260 children with CM (247 examined for retinopathy), 228 children with severe malarial anemia (SMA), and 30 community children with AP. Results Plasmodium falciparum HRP2 concentrations were higher in children with RP CM than RN CM (P = .006), with an area under the receiver operating characteristic curve of 0.61 (95% confidence interval, 0.53–0.68). Plasmodium falciparum HRP2 concentrations and sequestered parasite biomass were higher in RN CM than SMA (both P < .03) or AP (both P < .001). Conclusions Plasmodium falciparum HRP2 concentrations are higher in children with RN CM than in children with SMA or AP, suggesting that P falciparum is involved in disease pathogenesis in children with CM. Plasmodium falciparum HRP2 concentrations may provide a more feasible and consistent assessment of the contribution of P falciparum to severe disease than malaria retinopathy.
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Affiliation(s)
- Gregory S Park
- Department of Pediatrics, University of Minnesota Medical School, Minneapolis
| | - Robert O Opoka
- Makerere University College of Health Sciences, Kampala, Uganda
| | - Estela Shabani
- Department of Pediatrics, University of Minnesota Medical School, Minneapolis.,Ryan White Center for Pediatric Infectious Diseases and Global Health, Indiana University School of Medicine, Indianapolis
| | - Alexis Wypyszynski
- Department of Pediatrics, University of Minnesota Medical School, Minneapolis
| | - Benjamin Hanisch
- Division of Pediatric Infectious Diseases, Children's National Medical Center, Washington, District of Columbia
| | - Chandy C John
- Department of Pediatrics, University of Minnesota Medical School, Minneapolis.,Ryan White Center for Pediatric Infectious Diseases and Global Health, Indiana University School of Medicine, Indianapolis
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30
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Njunge JM, Oyaro IN, Kibinge NK, Rono MK, Kariuki SM, Newton CR, Berkley JA, Gitau EN. Cerebrospinal fluid markers to distinguish bacterial meningitis from cerebral malaria in children. Wellcome Open Res 2017. [DOI: 10.12688/wellcomeopenres.11958.1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Background. Few hospitals in high malaria endemic countries in Africa have the diagnostic capacity for clinically distinguishing acute bacterial meningitis (ABM) from cerebral malaria (CM). As a result, empirical use of antibiotics is necessary. A biochemical marker of ABM would facilitate precise clinical diagnosis and management of these infections and enable rational use of antibiotics. Methods. We used label-free protein quantification by mass spectrometry to identify cerebrospinal fluid (CSF) markers that distinguish ABM (n=37) from CM (n=22) in Kenyan children. Fold change (FC) and false discovery rates (FDR) were used to identify differentially expressed proteins. Subsequently, potential biomarkers were assessed for their ability to discriminate between ABM and CM using receiver operating characteristic (ROC) curves. Results. The host CSF proteome response to ABM (Haemophilus influenza and Streptococcus pneumoniae) is significantly different to CM. Fifty two proteins were differentially expressed (FDR<0.01, Log FC≥2), of which 83% (43/52) were upregulated in ABM compared to CM. Myeloperoxidase and lactotransferrin were present in 37 (100%) and 36 (97%) of ABM cases, respectively, but absent in CM (n=22). Area under the ROC curve (AUC), sensitivity, and specificity were assessed for myeloperoxidase (1, 1, and 1; 95% CI, 1-1) and lactotransferrin (0.98, 0.97, and 1; 95% CI, 0.96-1). Conclusion. Myeloperoxidase and lactotransferrin have a high potential to distinguish ABM from CM and thereby improve clinical management. Their validation requires a larger cohort of samples that includes other bacterial aetiologies of ABM.
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Small DS, Taylor TE, Postels DG, Beare NA, Cheng J, MacCormick IJ, Seydel KB. Evidence from a natural experiment that malaria parasitemia is pathogenic in retinopathy-negative cerebral malaria. eLife 2017; 6. [PMID: 28590246 PMCID: PMC5462542 DOI: 10.7554/elife.23699] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2016] [Accepted: 05/04/2017] [Indexed: 11/21/2022] Open
Abstract
Cerebral malaria (CM) can be classified as retinopathy-positive or retinopathy-negative, based on the presence or absence of characteristic retinal features. While malaria parasites are considered central to the pathogenesis of retinopathy-positive CM, their contribution to retinopathy-negative CM is largely unknown. One theory is that malaria parasites are innocent bystanders in retinopathy-negative CM and the etiology of the coma is entirely non-malarial. Because hospitals in malaria-endemic areas often lack diagnostic facilities to identify non-malarial causes of coma, it has not been possible to evaluate the contribution of malaria infection to retinopathy-negative CM. To overcome this barrier, we studied a natural experiment involving genetically inherited traits, and find evidence that malaria parasitemia does contribute to the pathogenesis of retinopathy-negative CM. A lower bound for the fraction of retinopathy-negative CM that would be prevented if malaria parasitemia were to be eliminated is estimated to be 0.93 (95% confidence interval: 0.68, 1). DOI:http://dx.doi.org/10.7554/eLife.23699.001 Malaria is a life-threatening disease caused by a parasite that is transferred between people by infected mosquitoes. Most infected individuals suffer flu-like symptoms, but in rare cases malaria can affect the brain, resulting in brain damage, coma or death. The World Health Organization defines a person as suffering from cerebral malaria if the person is in a coma, has malaria parasites in his or her blood, and has no known alternative cause of the coma. Patients suffering from cerebral malaria are categorized based on whether they have damage to the back of the eyes known as retinopathy. It had previously been found that children who died of “retinopathy-positive” cerebral malaria (i.e. those who had retinopathy) had malaria parasites stuck in small vessels in their brains, which likely caused the coma. By contrast, children who died of “retinopathy-negative” cerebral malaria lacked this parasitic condition, and often also had other infections that can cause a coma, such as meningitis or sepsis. Because hospitals in many of the areas most affected by malaria often lack the ability to identify what – other than malaria – caused a coma, it was not clear whether malaria parasites influence how retinopathy-negative cerebral malaria develops. People with certain genetic variants – such as those that underlie sickle cell disease – are protected against the symptoms of malaria infections, and so these variants should also protect against cerebral malaria cases caused by the parasites. Small et al. therefore looked through data that had been collected over several years from people who had been admitted to a hospital in Malawi for cerebral malaria. This revealed that the genetically inherited sickle cell trait is highly protective against retinopathy-negative (as well as retinopathy-positive) cerebral malaria. Therefore, malaria parasites do play a role in a substantial proportion of cases of retinopathy-negative cerebral malaria. Although Small et al. provide evidence that malaria parasites play a role in retinopathy-negative cerebral malaria, they may not be the only cause of the coma. In the future, the absence of retinopathy could be used as a sign to look for additional factors that contribute to the coma. Currently, all cerebral malaria patients are treated in the same way. Understanding how malaria parasites interact with other illnesses to produce a coma could lead to the development of targeted treatment plans for retinopathy-negative patients. DOI:http://dx.doi.org/10.7554/eLife.23699.002
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Affiliation(s)
- Dylan S Small
- Department of Statistics, The Wharton School, University of Pennsylvania, Philadelphia, United States
| | - Terrie E Taylor
- Department of Osteopathic Medical Specialties, College of Osteopathic Medicine, Michigan State University, East Lansing, United States.,Blantyre Malaria Project, Blantyre, Malawi
| | - Douglas G Postels
- Department of Neurology and Ophthalmology, College of Osteopathic Medicine, Michigan State University, East Lansing, United States
| | - Nicholas Av Beare
- Department of Eye and Vision Science, University of Liverpool, Liverpool, United Kingdom.,St. Paul's Eye Unit, Royal Liverpool University Hospital, Liverpool, United Kingdom
| | - Jing Cheng
- Department of Preventive and Restorative Dental Sciences, University of California, San Francisco, San Francisco, United States
| | - Ian Jc MacCormick
- Department of Eye and Vision Science, University of Liverpool, Liverpool, United Kingdom.,Malawi-Liverpool-Wellcome Trust Clinical Research Programme, Blantyre, Malawi
| | - Karl B Seydel
- Department of Osteopathic Medical Specialties, College of Osteopathic Medicine, Michigan State University, East Lansing, United States.,Blantyre Malaria Project, Blantyre, Malawi
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Villaverde C, Namazzi R, Shabani E, Opoka RO, John CC. Clinical Comparison of Retinopathy-Positive and Retinopathy-Negative Cerebral Malaria. Am J Trop Med Hyg 2017; 96:1176-1184. [PMID: 28138045 DOI: 10.4269/ajtmh.16-0315] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
AbstractCerebral malaria (CM) is a severe and often lethal complication of falciparum malaria. A classic malaria retinopathy is seen in some (retinopathy-positive [RP]) children but not others (retinopathy-negative [RN]), and is associated with increased parasite sequestration. It is unclear whether RN CM is a severe nonmalarial illness with incidental parasitemia or a less severe form of the same malarial illness as RP CM. Understanding the clinical differences between RP and RN CM may help shed light on the pathophysiology of malarial retinopathy. We compared clinical history, physical examination, laboratory findings, and outcomes of RP (N = 167) and RN (N = 87) children admitted to Mulago Hospital, Kampala, Uganda. Compared with RN children, RP children presented with a longer history of illness, as well as physical examination and laboratory findings indicative of more severe disease and organ damage. The hospital course of RP children was complicated by longer coma duration and a greater transfusion burden than RN children. Mortality did not differ significantly between RP and RN children (14.4% versus 8.0%, P = 0.14). Further, severity of retinal hemorrhage correlated with the majority of variables that differed between RP and RN children. The data suggest that RP and RN CM may reflect the spectrum of illness in CM, and that RN CM could be an earlier, less severe form of disease.
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Affiliation(s)
- Chandler Villaverde
- The Warren Alpert Medical School, Brown University, Providence, Rhode Island
| | - Ruth Namazzi
- Department of Paediatrics and Child Health, Makerere University College of Health Sciences, Kampala, Uganda
| | - Estela Shabani
- Department of Pediatrics, University of Minnesota, Minneapolis, Minnesota.,Department of Pediatrics, Indiana University, Indianapolis, Indiana
| | - Robert O Opoka
- Department of Paediatrics and Child Health, Makerere University College of Health Sciences, Kampala, Uganda
| | - Chandy C John
- Department of Pediatrics, University of Minnesota, Minneapolis, Minnesota.,Department of Pediatrics, Indiana University, Indianapolis, Indiana
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Bernabeu M, Smith JD. EPCR and Malaria Severity: The Center of a Perfect Storm. Trends Parasitol 2016; 33:295-308. [PMID: 27939609 DOI: 10.1016/j.pt.2016.11.004] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2016] [Revised: 11/07/2016] [Accepted: 11/10/2016] [Indexed: 12/20/2022]
Abstract
Severe malaria due to Plasmodium falciparum infection causes nearly half a million deaths per year. The different symptomatology and disease manifestations among patients have hampered understanding of severe malaria pathology and complicated efforts to develop targeted disease interventions. Infected erythrocyte sequestration in the microvasculature plays a critical role in the development of severe disease, and there is increasing evidence that cytoadherent parasites interact with host factors to enhance the damage caused by the parasite. The recent discovery that parasite binding to endothelial protein C receptor (EPCR) is associated with severe disease has suggested new mechanisms of pathology and provided new avenues for severe malaria adjunctive therapy research.
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Affiliation(s)
- Maria Bernabeu
- Center for Infectious Disease Research, Seattle, WA 98109, USA
| | - Joseph D Smith
- Center for Infectious Disease Research, Seattle, WA 98109, USA; Department of Global Health, University of Washington, Seattle, WA 98195, USA.
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Mbale EW, Moxon CA, Mukaka M, Chagomerana M, Glover S, Chisala N, Omar S, Molyneux M, Seydel K, Craig AG, Taylor T, Heyderman RS, Mallewa M. HIV coinfection influences the inflammatory response but not the outcome of cerebral malaria in Malawian children. J Infect 2016; 73:189-99. [PMID: 27311750 PMCID: PMC4990000 DOI: 10.1016/j.jinf.2016.05.012] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2016] [Revised: 05/23/2016] [Accepted: 05/28/2016] [Indexed: 11/21/2022]
Abstract
Objectives Study of the effect of HIV on disease progression in heterogeneous severe malaria syndromes with imprecise diagnostic criteria has led to varying results. Characteristic retinopathy refines cerebral malaria (CM) diagnosis, enabling more precise exploration of the hypothesis that HIV decreases the cytokine response in CM, leading to higher parasite density and a poor outcome. Methods We retrospectively reviewed data on clinical progression and laboratory parameters in 877 retinopathy-positive CM cases admitted 1996–2011 (14.4% HIV-infected) to a large hospital in Malawi. Admission plasma levels of TNF, interleukin-10, and soluble intercellular adhesion molecule (sICAM-1) were measured by ELISA in 135 retinopathy-positive CM cases. Results HIV-infected CM cases had lower median plasma levels of TNF (p = 0.008), interleukin-10 (p = 0.045) and sICAM-1 (p = 0.04) than HIV-uninfected cases. Although HIV-infected children were older and more likely to have co-morbidities, HIV-status did not significantly affect parasite density (p = 0.90) or outcome (24.8% infected, vs. 18.5% uninfected; p = 0.13). Conclusion In this well-characterised CM cohort, HIV-coinfection was associated with marked blunting of the inflammatory response but did not affect parasite density or outcome. These data highlight the complex influence of HIV on severe malaria and bring into question systemic inflammation as a primary driver of pathogenesis in human CM. Characteristic malaria retinopathy refined the diagnosis of cerebral malaria. HIV-infected cases had markedly lower TNF, IL10 and ICAM-1 than uninfected cases. HIV-infected children were older and more likely to have comorbidities. Peripheral parasite count, HRP2 and mortality were unaffected by HIV status.
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Affiliation(s)
- Emmie W Mbale
- Malawi-Liverpool-Wellcome Trust Clinical Research Programme, University of Malawi College of Medicine, Malawi; Department of Paediatrics, University of Malawi College of Medicine, Malawi
| | - Christopher A Moxon
- Malawi-Liverpool-Wellcome Trust Clinical Research Programme, University of Malawi College of Medicine, Malawi; Institute of Infection and Global Health, University of Liverpool, UK.
| | - Mavuto Mukaka
- Malawi-Liverpool-Wellcome Trust Clinical Research Programme, University of Malawi College of Medicine, Malawi
| | | | - Simon Glover
- School of Medicine, University of St. Andrews, UK
| | - Ngawina Chisala
- Malawi-Liverpool-Wellcome Trust Clinical Research Programme, University of Malawi College of Medicine, Malawi
| | - Sofia Omar
- Department of Paediatrics, University of Malawi College of Medicine, Malawi
| | - Malcolm Molyneux
- Malawi-Liverpool-Wellcome Trust Clinical Research Programme, University of Malawi College of Medicine, Malawi; Liverpool School of Tropical Medicine, UK
| | - Karl Seydel
- Blantyre Malaria Project, University of Malawi College of Medicine, Malawi; College of Osteopathic Medicine, Michigan State University, East Lansing, MI, United States
| | | | - Terrie Taylor
- Blantyre Malaria Project, University of Malawi College of Medicine, Malawi; College of Osteopathic Medicine, Michigan State University, East Lansing, MI, United States
| | - Robert S Heyderman
- Malawi-Liverpool-Wellcome Trust Clinical Research Programme, University of Malawi College of Medicine, Malawi; Liverpool School of Tropical Medicine, UK; University College London, UK
| | - Macpherson Mallewa
- Malawi-Liverpool-Wellcome Trust Clinical Research Programme, University of Malawi College of Medicine, Malawi; Department of Paediatrics, University of Malawi College of Medicine, Malawi
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Plasmodium falciparum Histidine-Rich Protein II Compromises Brain Endothelial Barriers and May Promote Cerebral Malaria Pathogenesis. mBio 2016; 7:mBio.00617-16. [PMID: 27273825 PMCID: PMC4959673 DOI: 10.1128/mbio.00617-16] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Cerebral malaria (CM) is a disease of the vascular endothelium caused by Plasmodium falciparum. It is characterized by parasite sequestration, inflammatory cytokine production, and vascular leakage. A distinguishing feature of P. falciparum infection is parasite production and secretion of histidine-rich protein II (HRPII). Plasma HRPII is a diagnostic and prognostic marker for falciparum malaria. We demonstrate that disruption of a human cerebral microvascular endothelial barrier by P. falciparum-infected erythrocytes depends on expression of HRPII. Purified recombinant or native HRPII can recapitulate these effects. HRPII action occurs via activation of the inflammasome, resulting in decreased integrity of tight junctions and increased endothelial permeability. We propose that HRPII is a virulence factor that may contribute to cerebral malaria by compromising endothelial barrier integrity within the central nervous system. Cerebral malaria is a devastating disease. Patients have high levels of the protein HRPII in their blood. We have found that endothelial cell barriers become leaky when treated with concentrations of HRPII similar to those found in patients. This result suggests that HRPII may be important in cerebral malaria. Our finding that HRPII functions by causing inflammation suggests points of intervention for therapy or vaccination against this disease.
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Severe adult malaria is associated with specific PfEMP1 adhesion types and high parasite biomass. Proc Natl Acad Sci U S A 2016; 113:E3270-9. [PMID: 27185931 DOI: 10.1073/pnas.1524294113] [Citation(s) in RCA: 74] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The interplay between cellular and molecular determinants that lead to severe malaria in adults is unexplored. Here, we analyzed parasite virulence factors in an infected adult population in India and investigated whether severe malaria isolates impair endothelial protein C receptor (EPCR), a protein involved in coagulation and endothelial barrier permeability. Severe malaria isolates overexpressed specific members of the Plasmodium falciparum var gene/PfEMP1 (P. falciparum erythrocyte membrane protein 1) family that bind EPCR, including DC8 var genes that have previously been linked to severe pediatric malaria. Machine learning analysis revealed that DC6- and DC8-encoding var transcripts in combination with high parasite biomass were the strongest indicators of patient hospitalization and disease severity. We found that DC8 CIDRα1 domains from severe malaria isolates had substantial differences in EPCR binding affinity and blockade activity for its ligand activated protein C. Additionally, even a low level of inhibition exhibited by domains from two cerebral malaria isolates was sufficient to interfere with activated protein C-barrier protective activities in human brain endothelial cells. Our findings demonstrate an interplay between parasite biomass and specific PfEMP1 adhesion types in the development of adult severe malaria, and indicate that low impairment of EPCR function may contribute to parasite virulence.
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Imported falciparum malaria in adults: host- and parasite-related factors associated with severity. The French prospective multicenter PALUREA cohort study. Intensive Care Med 2016; 42:1588-1596. [DOI: 10.1007/s00134-016-4356-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Accepted: 04/11/2016] [Indexed: 01/25/2023]
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Activated Neutrophils Are Associated with Pediatric Cerebral Malaria Vasculopathy in Malawian Children. mBio 2016; 7:e01300-15. [PMID: 26884431 PMCID: PMC4791846 DOI: 10.1128/mbio.01300-15] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Most patients with cerebral malaria (CM) sustain cerebral microvascular sequestration of Plasmodium falciparum-infected red blood cells (iRBCs). Although many young children are infected with P. falciparum, CM remains a rare outcome; thus, we hypothesized that specific host conditions facilitate iRBC cerebral sequestration. To identify these host factors, we compared the peripheral whole-blood transcriptomes of Malawian children with iRBC cerebral sequestration, identified as malarial-retinopathy-positive CM (Ret+CM), to the transcriptomes of children with CM and no cerebral iRBC sequestration, defined as malarial-retinopathy-negative CM (Ret-CM). Ret+CM was associated with upregulation of 103 gene set pathways, including cytokine, blood coagulation, and extracellular matrix (ECM) pathways (P < 0.01; false-discovery rate [FDR] of <0.05). Neutrophil transcripts were the most highly upregulated individual transcripts in Ret+CM patients. Activated neutrophils can modulate diverse host processes, including the ECM, inflammation, and platelet biology to potentially facilitate parasite sequestration. Therefore, we compared plasma neutrophil proteins and neutrophil chemotaxis between Ret+CM and Ret-CM patients. Plasma levels of human neutrophil elastase, myeloperoxidase, and proteinase 3, but not lactoferrin or lipocalin, were elevated in Ret+CM patients, and neutrophil chemotaxis was impaired, possibly related to increased plasma heme. Neutrophils were rarely seen in CM brain microvasculature autopsy samples, and no neutrophil extracellular traps were found, suggesting that a putative neutrophil effect on endothelial cell biology results from neutrophil soluble factors rather than direct neutrophil cellular tissue effects. Meanwhile, children with Ret-CM had lower levels of inflammation, higher levels of alpha interferon, and upregulation of Toll-like receptor pathways and other host transcriptional pathways, which may represent responses that do not favor cerebral iRBC sequestration. There were approximately 198 million cases of malaria worldwide in 2013, with an estimated 584,000 deaths occurring mostly in sub-Saharan African children. CM is a severe and rare form of Plasmodium falciparum infection and is associated with high rates of mortality and neurological morbidity, despite antimalarial treatment. A greater understanding of the pathophysiology of CM would allow the development of adjunctive therapies to improve clinical outcomes. A hallmark of CM is cerebral microvasculature sequestration of P. falciparum-infected red blood cells (iRBCs), which results in vasculopathy in some patients. Our data provide a global analysis of the host pathways associated with CM and newly identify an association of activated neutrophils with brain iRBC sequestration. Products of activated neutrophils could alter endothelial cell receptors and coagulation to facilitate iRBC adherence. Future studies can now examine the role of neutrophils in CM pathogenesis to improve health outcomes.
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Pappa V, Seydel K, Gupta S, Feintuch CM, Potchen MJ, Kampondeni S, Goldman-Yassen A, Veenstra M, Lopez L, Kim RS, Berman JW, Taylor T, Daily JP. Lipid metabolites of the phospholipase A2 pathway and inflammatory cytokines are associated with brain volume in paediatric cerebral malaria. Malar J 2015; 14:513. [PMID: 26691993 PMCID: PMC4687364 DOI: 10.1186/s12936-015-1036-1] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Accepted: 12/04/2015] [Indexed: 11/13/2022] Open
Abstract
Background Cerebral malaria (CM) remains a significant cause of morbidity and mortality in children in sub-Saharan Africa. CM mortality has been associated with increased brain volume, seen on neuroimaging studies. Methods To examine the potential role of blood metabolites and inflammatory mediators in increased brain volume in Malawian children with CM, an association study was performed between plasma metabolites, cytokine levels and phospholipase A2 (PLA2) activity with brain volume. Results The metabolomics analysis demonstrated arachidonic acid and other lysophospholipids to be positively associated with brain swelling. These lipids are products of the PLA2 enzyme and an association of plasma PLA2 enzymatic activity with brain swelling was confirmed. TNFα, which can upregulate PLA2 activity, was associated with brain volume. In addition, CCL2 and IL-8 were also associated with brain volume. Some of these cytokines can alter endothelial cell tight junction proteins and increase blood brain barrier permeability. Conclusions Taken together, paediatric CM brain volume was associated with products of the PLA2 pathway and inflammatory cytokines. Their role in causality is unknown. These molecules will need to undergo testing in vitro and in animal models to understand their role in processes of increased brain volume. These observations provide novel data on host physiology associated with paediatric CM brain swelling, and may both inform pathogenesis models and suggest adjunct therapies that could improve the morbidity and mortality associated with paediatric CM. Electronic supplementary material The online version of this article (doi:10.1186/s12936-015-1036-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Vasiliki Pappa
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, NY, 10461, USA.
| | - Karl 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, 48824, USA.
| | - Sanchit Gupta
- Department of Medicine (Infectious Diseases), Albert Einstein College of Medicine, Bronx, NY, 10461, USA.
| | - Catherine M Feintuch
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, NY, 10461, USA.
| | - Michael J Potchen
- Department of Radiology, University of Rochester, Rochester, NY, 14642, USA. .,Lusaka Apex Medical University, Medical Radiation Sciences, Lusaka, Zambia.
| | - Samuel Kampondeni
- Blantyre Malaria Project, University of Malawi College of Medicine, Blantyre, Malawi.
| | - Adam Goldman-Yassen
- Department of Medicine (Infectious Diseases), Albert Einstein College of Medicine, Bronx, NY, 10461, USA.
| | - Mike Veenstra
- Department of Pathology, Albert Einstein College of Medicine, Bronx, NY, 10461, USA.
| | - Lillie Lopez
- Department of Pathology, Albert Einstein College of Medicine, Bronx, NY, 10461, USA.
| | - Ryung S Kim
- Department of Epidemiology and Population Health, Albert Einstein College of Medicine, Bronx, NY, 10461, USA.
| | - Joan W Berman
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, NY, 10461, USA. .,Department of Pathology, Albert Einstein College of Medicine, Bronx, NY, 10461, 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, 48824, USA.
| | - Johanna P Daily
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, NY, 10461, USA. .,Department of Medicine (Infectious Diseases), Albert Einstein College of Medicine, Bronx, NY, 10461, USA.
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de Haan F, Onyamboko MA, Fanello CI, Woodrow CJ, Lubell Y, Boon WPC, Dondorp AM. Exploring health practitioners' acceptability of a prospective semi-quantitative pfHRP2 device to define severe malaria in the Democratic Republic of Congo. Malar J 2015; 14:503. [PMID: 26670489 PMCID: PMC4681050 DOI: 10.1186/s12936-015-0963-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2015] [Accepted: 10/24/2015] [Indexed: 11/22/2022] Open
Abstract
BACKGROUND A rapid diagnostic tool is being developed to discern severely ill children with severe malaria from children who are ill with alternative febrile diseases but have coincidental peripheral blood parasitaemia. The device semi-quantitatively measures plasma pfHRP2 and has the potential to reduce mortality in children with severe febrile illnesses by improving diagnosis. The aim of this study is to identify contributing and inhibiting factors that affect healthcare practitioners' acceptability of this prospective diagnostic device in a high malaria transmission setting in the Democratic Republic of Congo. METHODS Data were collected qualitatively by conducting semi-structured interviews with a purposeful sample of health professionals in Kinshasa, capital of Democratic Republic of Congo. In total, 11 interviews were held with professionals at four different institutes. RESULTS Four key findings emerged: (1) Congolese practitioners perceive the semi-quantitative pfHRP2 device as a welcome intervention as they recognize the limited reliability of their current diagnostic and therapeutic approaches to severe febrile illnesses; (2) compatibility of the semi-quantitative pfHRP2 device with clinical equipment and competences of Congolese health practitioners is considered to be limited, especially in rural settings; (3) a formal training programme is crucial for correct understanding and application of the semi-quantitative pfHRP2 device; and, (4) provision of evidence to practitioners, and support from health authorities would be important to establish confidence in the semi-quantitative pfHRP2 device. CONCLUSIONS Congolese practitioners perceive the prospective semi-quantitative pfHRP2 device as a welcome addition to their clinical equipment. The device could improve current diagnostic work-up of severe febrile illness, which might consequently improve treatment choices. However, despite this recognized potential, several hurdles and drivers need to be taken into account when implementing this device in DR Congo.
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Affiliation(s)
- Freek de Haan
- Innovation Studies Group, Copernicus Institute, Utrecht University, Utrecht, The Netherlands.
| | - Marie A Onyamboko
- Kinshasa School of Public Health, Kinshasa, Democratic Republic of Congo.
| | - Caterina I Fanello
- Centre for Tropical Medicine, Nuffield Department of Medicine, University of Oxford, Oxford, UK.
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.
| | - Charles J Woodrow
- Centre for Tropical Medicine, Nuffield Department of Medicine, University of Oxford, Oxford, UK.
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.
| | - Yoel Lubell
- Centre for Tropical Medicine, Nuffield Department of Medicine, University of Oxford, Oxford, UK.
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.
| | - Wouter P C Boon
- Innovation Studies Group, Copernicus Institute, Utrecht University, Utrecht, The Netherlands.
| | - Arjen M Dondorp
- Centre for Tropical Medicine, Nuffield Department of Medicine, University of Oxford, Oxford, UK.
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.
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Differential Plasmodium falciparum surface antigen expression among children with Malarial Retinopathy. Sci Rep 2015; 5:18034. [PMID: 26657042 PMCID: PMC4677286 DOI: 10.1038/srep18034] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Accepted: 11/10/2015] [Indexed: 11/08/2022] Open
Abstract
Retinopathy provides a window into the underlying pathology of life-threatening malarial coma ("cerebral malaria"), allowing differentiation between 1) coma caused by sequestration of Plasmodium falciparum-infected erythrocytes in the brain and 2) coma with other underlying causes. Parasite sequestration in the brain is mediated by PfEMP1; a diverse parasite antigen that is inserted into the surface of infected erythrocytes and adheres to various host receptors. PfEMP1 sub-groups called "DC8" and "DC13" have been proposed to cause brain pathology through interactions with endothelial protein C receptor. To test this we profiled PfEMP1 gene expression in parasites from children with clinically defined cerebral malaria, who either had or did not have accompanying retinopathy. We found no evidence for an elevation of DC8 or DC13 PfEMP1 expression in children with retinopathy. However, the proportional expression of a broad subgroup of PfEMP1 called "group A" was elevated in retinopathy patients suggesting that these variants may play a role in the pathology of cerebral malaria. Interventions targeting group A PfEMP1 may be effective at reducing brain pathology.
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Use of a rapid test to assess plasma Plasmodium falciparum HRP2 and guide management of severe febrile illness. Malar J 2015; 14:362. [PMID: 26391009 PMCID: PMC4578847 DOI: 10.1186/s12936-015-0900-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Accepted: 09/12/2015] [Indexed: 11/24/2022] Open
Abstract
Background Plasma Plasmodium falciparum histidine-rich protein-2 (PfHRP2) is the most accurate biomarker for severe malaria, but its measurement by ELISA has been considered too unwieldy to incorporate into clinical management. Methods Plasma samples covering a wide range of PfHRP2 concentrations were applied to rapid diagnostic tests (RDTs). RDTs were read by eye and digital capture, and PfHRP2 concentrations were measured via serial dilution with results compared to ELISA readings. Results The Paracheck® brand showed the strongest correlation (r2 = 0.963) as well as the lowest inter-observer variability (combined kappa across band intensities for three observers = 0.938). Plasma PfHRP2 measurement via serial dilution showed minimal bias compared to ELISA and acceptable limits of agreement. Three different dilutions of a well characterized set of admission samples from uncomplicated and severe malaria patients studied in a low transmission setting gave an area under the receiver operator characteristic curve of 0.844 in terms of identifying severe malaria. Conclusions These studies show that plasma PfHRP2 can be assessed via a single RDT, with application of a plasma dilution of 1:5 or 1:10 providing useful diagnostic information to assist in patient management or clinical trial inclusion.
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Fatal Pediatric Cerebral Malaria Is Associated with Intravascular Monocytes and Platelets That Are Increased with HIV Coinfection. mBio 2015; 6:e01390-15. [PMID: 26396242 PMCID: PMC4611030 DOI: 10.1128/mbio.01390-15] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Cerebral malaria (CM) is a major contributor to malaria deaths, but its pathophysiology is not well understood. While sequestration of parasitized erythrocytes is thought to be critical, the roles of inflammation and coagulation are controversial. In a large series of Malawian children hospitalized with CM, HIV coinfection was more prevalent than in pediatric population estimates (15% versus 2%, P < 0.0001, chi-square test), with higher mortality than that seen in HIV-uninfected children (23% versus 17%, P = 0.0178, chi-square test). HIV-infected (HIV+) children with autopsy-confirmed CM were older than HIV-uninfected children (median age, 99 months versus 32 months, P = 0.0007, Mann-Whitney U test) and appeared to lack severe immunosuppression. Because HIV infection is associated with dysregulated inflammation and platelet activation, we performed immunohistochemistry analysis for monocytes, platelets, and neutrophils in brain tissue from HIV+ and HIV-uninfected children with fatal CM. Children with autopsy-confirmed CM had significantly (>9 times) more accumulations of intravascular monocytes and platelets, but not neutrophils, than did children with nonmalarial causes of coma. The monocyte and platelet accumulations were significantly (>2-fold) greater in HIV+ children than in HIV-uninfected children with autopsy-confirmed CM. Our findings indicate that HIV is a risk factor for CM and for death from CM, independent of traditional measures of HIV disease severity. Brain histopathology supports the hypotheses that inflammation and coagulation contribute to the pathogenesis of pediatric CM and that immune dysregulation in HIV+ children exacerbates the pathological features associated with CM. Importance There are nearly 1 million malaria deaths yearly, primarily in sub-Saharan African children. Cerebral malaria (CM), marked by coma and sequestered malaria parasites in brain blood vessels, causes half of these deaths, although the mechanisms causing coma and death are uncertain. Sub-Saharan Africa has a high HIV prevalence, with 3 million HIV-infected (HIV+) children, but the effects of HIV on CM pathogenesis and mortality are unknown. In a study of pediatric CM in Malawi, HIV prevalence was high and CM-attributed mortality was higher in HIV+ than in HIV-uninfected children. Brain pathology in children with fatal CM was notable not only for sequestered malaria parasites but also for intravascular accumulations of monocytes and platelets that were more severe in HIV+ children. Our findings raise the possibility that HIV+ children at risk for malaria may benefit from targeted malaria prophylaxis and that adjunctive treatments targeting inflammation and/or coagulation may improve CM outcomes. There are nearly 1 million malaria deaths yearly, primarily in sub-Saharan African children. Cerebral malaria (CM), marked by coma and sequestered malaria parasites in brain blood vessels, causes half of these deaths, although the mechanisms causing coma and death are uncertain. Sub-Saharan Africa has a high HIV prevalence, with 3 million HIV-infected (HIV+) children, but the effects of HIV on CM pathogenesis and mortality are unknown. In a study of pediatric CM in Malawi, HIV prevalence was high and CM-attributed mortality was higher in HIV+ than in HIV-uninfected children. Brain pathology in children with fatal CM was notable not only for sequestered malaria parasites but also for intravascular accumulations of monocytes and platelets that were more severe in HIV+ children. Our findings raise the possibility that HIV+ children at risk for malaria may benefit from targeted malaria prophylaxis and that adjunctive treatments targeting inflammation and/or coagulation may improve CM outcomes.
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Wassmer SC, Taylor TE, Rathod PK, Mishra SK, Mohanty S, Arevalo-Herrera M, Duraisingh MT, Smith JD. Investigating the Pathogenesis of Severe Malaria: A Multidisciplinary and Cross-Geographical Approach. Am J Trop Med Hyg 2015; 93:42-56. [PMID: 26259939 PMCID: PMC4574273 DOI: 10.4269/ajtmh.14-0841] [Citation(s) in RCA: 102] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2014] [Accepted: 03/10/2015] [Indexed: 01/14/2023] Open
Abstract
More than a century after the discovery of Plasmodium spp. parasites, the pathogenesis of severe malaria is still not well understood. The majority of malaria cases are caused by Plasmodium falciparum and Plasmodium vivax, which differ in virulence, red blood cell tropism, cytoadhesion of infected erythrocytes, and dormant liver hypnozoite stages. Cerebral malaria coma is one of the most severe manifestations of P. falciparum infection. Insights into its complex pathophysiology are emerging through a combination of autopsy, neuroimaging, parasite binding, and endothelial characterizations. Nevertheless, important questions remain regarding why some patients develop life-threatening conditions while the majority of P. falciparum-infected individuals do not, and why clinical presentations differ between children and adults. For P. vivax, there is renewed recognition of severe malaria, but an understanding of the factors influencing disease severity is limited and remains an important research topic. Shedding light on the underlying disease mechanisms will be necessary to implement effective diagnostic tools for identifying and classifying severe malaria syndromes and developing new therapeutic approaches for severe disease. This review highlights progress and outstanding questions in severe malaria pathophysiology and summarizes key areas of pathogenesis research within the International Centers of Excellence for Malaria Research program.
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Affiliation(s)
| | | | | | | | | | | | | | - Joseph D. Smith
- Division of Parasitology, Department of Microbiology, New York University School of Medicine, New York, New York; Department of Pathology, Sydney Medical School, The University of Sydney, Sydney, Australia; Department of Osteopathic Medical Specialties, College of Osteopathic Medicine, Michigan State University, East Lansing, Michigan; Blantyre Malaria Project, University of Malawi College of Medicine, Blantyre, Malawi; Departments of Chemistry and Global Health, University of Washington, Seattle, Washington; Department of Internal Medicine, Ispat General Hospital, Orissa, India; Caucaseco Scientific Research Center, Cali, Colombia; Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, Massachusetts; Seattle Biomedical Research Institute, Seattle, Washington; Department of Global Health, University of Washington, Seattle, Washington
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Taylor TE, Molyneux ME. The pathogenesis of pediatric cerebral malaria: eye exams, autopsies, and neuroimaging. Ann N Y Acad Sci 2015; 1342:44-52. [PMID: 25708306 DOI: 10.1111/nyas.12690] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2014] [Revised: 12/02/2014] [Accepted: 12/18/2014] [Indexed: 12/23/2022]
Abstract
Several advances in our understanding of pediatric cerebral malaria (CM) have been made over the past 25 years. Accurate clinical diagnosis is enhanced by the identification of a characteristic retinopathy, visible by direct or indirect ophthalmoscopy, the retinal changes (retinal whitening, vessel color changes, white-centered hemorrhages) being consistently associated with intracerebral sequestration of parasites in autopsy studies. Autopsies have yielded information at tissue levels in fatal CM, but new insights into critical pathogenetic processes have emerged from neuroimaging studies, which, unlike autopsy-based studies, permit serial observations over time and allow comparisons between fatal cases and survivors. Brain swelling has emerged as the major risk factor for death, and, among survivors, brain volume diminishes spontaneously over 24-48 hours. Studies of life-threatening and fatal malaria are suggesting new approaches to identifying and caring for those at highest risk; potential adjuvants should be evaluated and implemented where they are most needed.
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Affiliation(s)
- Terrie E Taylor
- Department of Osteopathic Medical Specialties, College of Osteopathic Medicine, Michigan State University, East Lansing, MI; Blantyre Malaria Project, University of Malawi College of Medicine, Blantyre, Malawi
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MacCormick IJC, Czanner G, Faragher B. Developing retinal biomarkers of neurological disease: an analytical perspective. Biomark Med 2015; 9:691-701. [PMID: 26174843 PMCID: PMC4822679 DOI: 10.2217/bmm.15.17] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The inaccessibility of the brain poses a problem for neuroscience. Scientists have traditionally responded by developing biomarkers for brain physiology and disease. The retina is an attractive source of biomarkers since it shares many features with the brain. Some even describe the retina as a 'window' to the brain, implying that retinal signs are analogous to brain disease features. However, new analytical methods are needed to show whether or not retinal signs really are equivalent to brain abnormalities, since this requires greater evidence than direct associations between retina and brain. We, therefore propose a new way to think about, and test, how clearly one might see the brain through the retinal window, using cerebral malaria as a case study.
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Affiliation(s)
- Ian JC MacCormick
- Department of Eye & Vision Science, University of Liverpool, Liverpool, UK
- Malawi-Liverpool-Wellcome Trust Clinical Research Programme, Blantyre, Malawi
- Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, UK
| | - Gabriela Czanner
- Department of Eye & Vision Science, University of Liverpool, Liverpool, UK
- Department of Biostatistics, University of Liverpool, Liverpool, United Kingdom
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Imwong M, Woodrow CJ, Hendriksen ICE, Veenemans J, Verhoef H, Faiz MA, Mohanty S, Mishra S, Mtove G, Gesase S, Seni A, Chhaganlal KD, Day NPJ, Dondorp AM, White NJ. Plasma concentration of parasite DNA as a measure of disease severity in falciparum malaria. J Infect Dis 2014; 211:1128-33. [PMID: 25344520 PMCID: PMC4354984 DOI: 10.1093/infdis/jiu590] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In malaria-endemic areas, Plasmodium falciparum parasitemia is common in apparently healthy children and severe malaria is commonly misdiagnosed in patients with incidental parasitemia. We assessed whether the plasma Plasmodium falciparum DNA concentration is a useful datum for distinguishing uncomplicated from severe malaria in African children and Asian adults. P. falciparum DNA concentrations were measured by real-time polymerase chain reaction (PCR) in 224 African children (111 with uncomplicated malaria and 113 with severe malaria) and 211 Asian adults (100 with uncomplicated malaria and 111 with severe malaria) presenting with acute falciparum malaria. The diagnostic accuracy of plasma P. falciparum DNA concentrations in identifying severe malaria was 0.834 for children and 0.788 for adults, similar to that of plasma P. falciparum HRP2 levels and substantially superior to that of parasite densities (P < .0001). The diagnostic accuracy of plasma P. falciparum DNA concentrations plus plasma P. falciparum HRP2 concentrations was significantly greater than that of plasma P. falciparum HRP2 concentrations alone (0.904 for children [P = .004] and 0.847 for adults [P = .003]). Quantitative real-time PCR measurement of parasite DNA in plasma is a useful method for diagnosing severe falciparum malaria on fresh or archived plasma samples.
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Affiliation(s)
| | - Charles J Woodrow
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand Centre for Tropical Medicine, Churchill Hospital, University of Oxford
| | - Ilse C E Hendriksen
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand Centre for Tropical Medicine, Churchill Hospital, University of Oxford
| | - Jacobien Veenemans
- Cell Biology and Immunology Group, Wageningen University Laboratory for Microbiology and Infection Control, Amphia Hospital, Breda, the Netherlands
| | - Hans Verhoef
- MRC International Nutrition Group, London School of Hygiene and Tropical Medicine, United Kingdom Cell Biology and Immunology Group, Wageningen University MRC Keneba, the Gambia
| | | | | | - Saroj Mishra
- Department of Medicine, Ispat Hospital, Rourkela, India
| | - George Mtove
- Amani Centre, National Institute for Medical Research, Muheza
| | - Samwel Gesase
- Korogwe Research Laboratory, National Institute for Medical Research, Tanga, Tanzania
| | | | - Kajal D Chhaganlal
- Hospital Central da Beira Faculty of Health Sciences, Catholic University of Mozambique, Beira, Mozambique
| | - Nicholas P J Day
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand Centre for Tropical Medicine, Churchill Hospital, University of Oxford
| | - Arjen M Dondorp
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand Centre for Tropical Medicine, Churchill Hospital, University of Oxford
| | - Nicholas J White
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand Centre for Tropical Medicine, Churchill Hospital, University of Oxford
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Storm J, Craig AG. Pathogenesis of cerebral malaria--inflammation and cytoadherence. Front Cell Infect Microbiol 2014; 4:100. [PMID: 25120958 PMCID: PMC4114466 DOI: 10.3389/fcimb.2014.00100] [Citation(s) in RCA: 113] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2014] [Accepted: 07/07/2014] [Indexed: 01/08/2023] Open
Abstract
Despite decades of research on cerebral malaria (CM) there is still a paucity of knowledge about what actual causes CM and why certain people develop it. Although sequestration of P. falciparum infected red blood cells has been linked to pathology, it is still not clear if this is directly or solely responsible for this clinical syndrome. Recent data have suggested that a combination of parasite variant types, mainly defined by the variant surface antigen, P. falciparum erythrocyte membrane protein 1 (PfEMP1), its receptors, coagulation and host endothelial cell activation (or inflammation) are equally important. This makes CM a multi-factorial disease and a challenge to unravel its causes to decrease its detrimental impact.
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Affiliation(s)
- Janet Storm
- Department of Parasitology, Liverpool School of Tropical Medicine Liverpool, UK ; Malawi Liverpool Wellcome Trust Clinical Research Programme (MLW), University of Malawi College of Medicine Blantyre, Malawi
| | - Alister G Craig
- Department of Parasitology, Liverpool School of Tropical Medicine Liverpool, UK
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