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Ramos S, Jeney V, Figueiredo A, Paixão T, Sambo MR, Quinhentos V, Martins R, Gouveia Z, Carlos AR, Ferreira A, Pais TF, Lainé H, Faísca P, Rebelo S, Cardoso S, Tolosano E, Penha-Gonçalves C, Soares MP. Targeting circulating labile heme as a defense strategy against malaria. Life Sci Alliance 2024; 7:e202302276. [PMID: 38307624 PMCID: PMC10837040 DOI: 10.26508/lsa.202302276] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2023] [Revised: 01/23/2024] [Accepted: 01/24/2024] [Indexed: 02/04/2024] Open
Abstract
Severe presentations of malaria emerge as Plasmodium (P.) spp. parasites invade and lyse red blood cells (RBC), producing extracellular hemoglobin (HB), from which labile heme is released. Here, we tested whether scavenging of extracellular HB and/or labile heme, by haptoglobin (HP) and/or hemopexin (HPX), respectively, counter the pathogenesis of severe presentations of malaria. We found that circulating labile heme is an independent risk factor for cerebral and non-cerebral presentations of severe P. falciparum malaria in children. Labile heme was negatively correlated with circulating HP and HPX, which were, however, not risk factors for severe P. falciparum malaria. Genetic Hp and/or Hpx deletion in mice led to labile heme accumulation in plasma and kidneys, upon Plasmodium infection This was associated with higher incidence of mortality and acute kidney injury (AKI) in ageing but not adult Plasmodium-infected mice, and was corroborated by an inverse correlation between heme and HPX with serological markers of AKI in P. falciparum malaria. In conclusion, HP and HPX act in an age-dependent manner to prevent the pathogenesis of severe presentation of malaria in mice and presumably in humans.
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Affiliation(s)
- Susana Ramos
- https://ror.org/04b08hq31 Instituto Gulbenkian de Ciência, Oeiras, Portugal
| | - Viktoria Jeney
- https://ror.org/04b08hq31 Instituto Gulbenkian de Ciência, Oeiras, Portugal
| | - Ana Figueiredo
- https://ror.org/04b08hq31 Instituto Gulbenkian de Ciência, Oeiras, Portugal
| | - Tiago Paixão
- https://ror.org/04b08hq31 Instituto Gulbenkian de Ciência, Oeiras, Portugal
| | - Maria Rosário Sambo
- Hospital Pediátrico David Bernardino, Luanda, Angola
- Faculdade de Medicina, Universidade Agostinho Neto, Luanda, Angola
| | - Vatúsia Quinhentos
- Hospital Pediátrico David Bernardino, Luanda, Angola
- Faculdade de Medicina, Universidade Agostinho Neto, Luanda, Angola
| | - Rui Martins
- https://ror.org/04b08hq31 Instituto Gulbenkian de Ciência, Oeiras, Portugal
| | - Zélia Gouveia
- https://ror.org/04b08hq31 Instituto Gulbenkian de Ciência, Oeiras, Portugal
| | - Ana Rita Carlos
- https://ror.org/04b08hq31 Instituto Gulbenkian de Ciência, Oeiras, Portugal
| | - Ana Ferreira
- https://ror.org/04b08hq31 Instituto Gulbenkian de Ciência, Oeiras, Portugal
| | - Teresa F Pais
- https://ror.org/04b08hq31 Instituto Gulbenkian de Ciência, Oeiras, Portugal
| | - Hugo Lainé
- https://ror.org/04b08hq31 Instituto Gulbenkian de Ciência, Oeiras, Portugal
| | - Pedro Faísca
- https://ror.org/04b08hq31 Instituto Gulbenkian de Ciência, Oeiras, Portugal
| | - Sofia Rebelo
- https://ror.org/04b08hq31 Instituto Gulbenkian de Ciência, Oeiras, Portugal
| | - Silvia Cardoso
- https://ror.org/04b08hq31 Instituto Gulbenkian de Ciência, Oeiras, Portugal
| | - Emanuela Tolosano
- Department Molecular Biotechnology and Health Sciences, University of Torino, Torino, Italy
| | | | - Miguel P Soares
- https://ror.org/04b08hq31 Instituto Gulbenkian de Ciência, Oeiras, Portugal
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Gul S, Ackerman HC, Daniel-Ribeiro CT, Carvalho LJM. Intravenous whole blood transfusion results in faster recovery of vascular integrity and increased survival in experimental cerebral malaria. Mem Inst Oswaldo Cruz 2023; 117:e220184. [PMID: 36700582 PMCID: PMC9870258 DOI: 10.1590/0074-02760220184] [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: 08/12/2022] [Accepted: 12/06/2022] [Indexed: 01/27/2023] Open
Abstract
BACKGROUND Cerebral malaria is a lethal complication of Plasmodium falciparum infections in need of better therapies. Previous work in murine experimental cerebral malaria (ECM) indicated that the combination of artemether plus intraperitoneal whole blood improved vascular integrity and increased survival compared to artemether alone. However, the effects of blood or plasma transfusion administered via the intravenous route have not previously been evaluated in ECM. OBJECTIVES To evaluate the effects of intravenous whole blood compared to intravenous plasma on hematological parameters, vascular integrity, and survival in artemether-treated ECM. METHODS Mice with late-stage ECM received artemether alone or in combination with whole blood or plasma administered via the jugular vein. The outcome measures were hematocrit and platelets; plasma angiopoietin 1, angiopoietin 2, and haptoglobin; blood-brain barrier permeability; and survival. FINDINGS Survival increased from 54% with artemether alone to 90% with the combination of artemether and intravenous whole blood. Intravenous plasma lowered survival to 18%. Intravenous transfusion provided fast and pronounced recoveries of hematocrit, platelets, angiopoietins levels and blood brain barrier integrity. MAIN CONCLUSIONS The outcome of artemether-treated ECM was improved by intravenous whole blood but worsened by intravenous plasma. Compared to prior studies of transfusion via the intraperitoneal route, intravenous administration was more efficacious.
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Affiliation(s)
- Saba Gul
- Fundação Oswaldo Cruz-Fiocruz, Instituto Oswaldo Cruz, Laboratório de Pesquisa em Malária, Rio de Janeiro, RJ, Brasil
| | - Hans C Ackerman
- National Institutes of Health, National Institute of Allergy and Infectious Diseases, Laboratory of Malaria and Vector Research, Rockville, MD, USA
| | - Cláudio Tadeu Daniel-Ribeiro
- Fundação Oswaldo Cruz-Fiocruz, Instituto Oswaldo Cruz, Laboratório de Pesquisa em Malária, Rio de Janeiro, RJ, Brasil
| | - Leonardo JM Carvalho
- Fundação Oswaldo Cruz-Fiocruz, Instituto Oswaldo Cruz, Laboratório de Pesquisa em Malária, Rio de Janeiro, RJ, Brasil,+ Corresponding author:
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Brain endothelial STING1 activation by Plasmodium-sequestered heme promotes cerebral malaria via type I IFN response. Proc Natl Acad Sci U S A 2022; 119:e2206327119. [PMID: 36037380 PMCID: PMC9457060 DOI: 10.1073/pnas.2206327119] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
CM results from loss of blood–brain endothelial barrier function caused by unrestrained inflammatory response in the natural course of infection by Plasmodium parasites. However, the role of brain endothelium in triggering inflammatory mechanisms is still undetermined. We found that the innate immune sensor STING1 is crucial for production of IFNβ by brain endothelial cells in Plasmodium-infected mice. This in turn stimulates CXCL10-mediated recruitment of leukocytes and subsequent brain inflammation and tissue damage. We identified within extracellular particles released from Plasmodium-infected erythrocytes, a fraction containing products of hemoglobin degradation, namely, heme, which we show can bind STING1. Our results unravel a mechanism of CM immunopathogenesis: Heme contained in extracellular particles triggers the STING/IFNβ/CXCL10 axis in brain endothelial cells. Cerebral malaria (CM) is a life-threatening form of Plasmodium falciparum infection caused by brain inflammation. Brain endothelium dysfunction is a hallmark of CM pathology, which is also associated with the activation of the type I interferon (IFN) inflammatory pathway. The molecular triggers and sensors eliciting brain type I IFN cellular responses during CM remain largely unknown. We herein identified the stimulator of interferon response cGAMP interactor 1 (STING1) as the key innate immune sensor that induces Ifnβ1 transcription in the brain of mice infected with Plasmodium berghei ANKA (Pba). This STING1/IFNβ-mediated response increases brain CXCL10 governing the extent of brain leukocyte infiltration and blood–brain barrier (BBB) breakdown, and determining CM lethality. The critical role of brain endothelial cells (BECs) in fueling type I IFN–driven brain inflammation was demonstrated in brain endothelial–specific IFNβ-reporter and STING1-deficient Pba-infected mice, which were significantly protected from CM lethality. Moreover, extracellular particles (EPs) released from Pba-infected erythrocytes activated the STING1-dependent type I IFN response in BECs, a response requiring intracellular acidification. Fractionation of the EPs enabled us to identify a defined fraction carrying hemoglobin degradation remnants that activates STING1/IFNβ in the brain endothelium, a process correlated with heme content. Notably, stimulation of STING1-deficient BECs with heme, docking experiments, and in vitro binding assays unveiled that heme is a putative STING1 ligand. This work shows that heme resultant from the parasite heterotrophic activity operates as an alarmin, triggering brain endothelial inflammatory responses via the STING1/IFNβ/CXCL10 axis crucial to CM pathogenesis and lethality.
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Chandana M, Anand A, Ghosh S, Das R, Beura S, Jena S, Suryawanshi AR, Padmanaban G, Nagaraj VA. Malaria parasite heme biosynthesis promotes and griseofulvin protects against cerebral malaria in mice. Nat Commun 2022; 13:4028. [PMID: 35821013 PMCID: PMC9276668 DOI: 10.1038/s41467-022-31431-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2021] [Accepted: 06/16/2022] [Indexed: 11/08/2022] Open
Abstract
Heme-biosynthetic pathway of malaria parasite is dispensable for asexual stages, but essential for mosquito and liver stages. Despite having backup mechanisms to acquire hemoglobin-heme, pathway intermediates and/or enzymes from the host, asexual parasites express heme pathway enzymes and synthesize heme. Here we show heme synthesized in asexual stages promotes cerebral pathogenesis by enhancing hemozoin formation. Hemozoin is a parasite molecule associated with inflammation, aberrant host-immune responses, disease severity and cerebral pathogenesis. The heme pathway knockout parasites synthesize less hemozoin, and mice infected with knockout parasites are protected from cerebral malaria and death due to anemia is delayed. Biosynthetic heme regulates food vacuole integrity and the food vacuoles from knockout parasites are compromised in pH, lipid unsaturation and proteins, essential for hemozoin formation. Targeting parasite heme synthesis by griseofulvin-a FDA-approved antifungal drug, prevents cerebral malaria in mice and provides an adjunct therapeutic option for cerebral and severe malaria.
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Affiliation(s)
- Manjunatha Chandana
- Infectious Disease Biology, Institute of Life Sciences, Bhubaneswar, 751023, Odisha, India
- School of Biotechnology, Kalinga Institute of Industrial Technology, Bhubaneswar, 751024, Odisha, India
| | - Aditya Anand
- Infectious Disease Biology, Institute of Life Sciences, Bhubaneswar, 751023, Odisha, India
- Regional Centre for Biotechnology, Faridabad, 121001, Haryana, India
| | - Sourav Ghosh
- Infectious Disease Biology, Institute of Life Sciences, Bhubaneswar, 751023, Odisha, India
- Regional Centre for Biotechnology, Faridabad, 121001, Haryana, India
| | - Rahul Das
- Infectious Disease Biology, Institute of Life Sciences, Bhubaneswar, 751023, Odisha, India
- Regional Centre for Biotechnology, Faridabad, 121001, Haryana, India
| | - Subhashree Beura
- Infectious Disease Biology, Institute of Life Sciences, Bhubaneswar, 751023, Odisha, India
| | - Sarita Jena
- Infectious Disease Biology, Institute of Life Sciences, Bhubaneswar, 751023, Odisha, India
| | | | - Govindarajan Padmanaban
- Department of Biochemistry, Indian Institute of Science, Bangalore, 560012, Karnataka, India
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Dalapati T, Moore JM. Hemozoin: a Complex Molecule with Complex Activities. CURRENT CLINICAL MICROBIOLOGY REPORTS 2022; 8:87-102. [PMID: 35096512 DOI: 10.1007/s40588-021-00166-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Purpose of Review Malaria is a disease caused by parasites that reside in host red blood cells and use hemoglobin as a nutrient source. Heme released by hemoglobin catabolism is modified by the parasite to produce hemozoin (HZ), which has toxic effects on the host. Experimentation aiming to elucidate how HZ contributes to malaria pathogenesis has utilized different preparations of this molecule, complicating interpretation and comparison of findings. We examine natural synthesis and isolation of HZ and highlight studies that have used multiple preparations, including synthetic forms, in a comparative fashion. Recent Findings Recent work utilizing sophisticated imaging and detection techniques reveals important molecular characteristics of HZ synthesis and biochemistry. Other recent studies further refine understanding of contributions of HZ to malaria pathogenesis yet highlight the continuing need to characterize HZ preparations and contextualize experimental conditions in the in vivo infection milieu. Summary This review highlights the necessity of collectively determining what is physiologically relevant HZ. Characterization of isolated natural HZ and use of multiple preparations in each study are recommended with application of in vivo studies whenever possible. Adoption of such practices is expected to improve reproducibility of results and elucidate the myriad of ways that HZ participates in malaria pathogenesis.
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Affiliation(s)
- Trisha Dalapati
- Duke University School of Medicine, Duke University, Durham, NC, USA
| | - Julie M Moore
- Department of Infectious Diseases and Immunology, College of Veterinary Medicine, University of Florida, Gainesville, FL, USA
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Whole blood transfusion improves vascular integrity and increases survival in artemether-treated experimental cerebral malaria. Sci Rep 2021; 11:12077. [PMID: 34103601 PMCID: PMC8187502 DOI: 10.1038/s41598-021-91499-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Accepted: 05/25/2021] [Indexed: 01/28/2023] Open
Abstract
Pathological features observed in both human and experimental cerebral malaria (ECM) are endothelial dysfunction and changes in blood components. Blood transfusion has been routinely used in patients with severe malarial anemia and can also benefit comatose and acidotic malaria patients. In the present study Plasmodium berghei-infected mice were transfused intraperitoneally with 200 μL of whole blood along with 20 mg/kg of artemether. ECM mice showed severe thrombocytopenia and decreases in hematocrit. Artemether treatment markedly aggravated anemia within 24 h. Whole blood administration significantly prevented further drop in hematocrit and partially restored the platelet count. Increased levels of plasma angiopoietin-2 (Ang-2) remained high 24 h after artemether treatment but returned to normal levels 24 h after blood transfusion, indicating reversal to quiescence. Ang-1 was depleted in ECM mice and levels were not restored by any treatment. Blood transfusion prevented the aggravation of the breakdown of blood brain barrier after artemether treatment and decreased spleen congestion without affecting splenic lymphocyte populations. Critically, blood transfusion resulted in markedly improved survival of mice with ECM (75.9% compared to 50.9% receiving artemether only). These findings indicate that whole blood transfusion can be an effective adjuvant therapy for cerebral malaria.
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Ackerman H, Ayestaran A, Olola CHO, Jallow M, Agbenyega T, Bojang K, Roberts DJ, Krishna S, Kremsner PG, Newton CR, Taylor T, Valim C, Casals-Pascual C. The effect of blood transfusion on outcomes among African children admitted to hospital with Plasmodium falciparum malaria: a prospective, multicentre observational study. Lancet Haematol 2020; 7:e789-e797. [PMID: 33091354 PMCID: PMC7611367 DOI: 10.1016/s2352-3026(20)30288-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 08/31/2020] [Accepted: 09/02/2020] [Indexed: 01/13/2023]
Abstract
BACKGROUND Infection with Plasmodium falciparum leads to severe malaria and death in approximately 400 000 children each year in sub-Saharan Africa. Blood transfusion might benefit some patients with malaria but could potentially harm others. The aim of this study was to estimate the association between transfusion and death among children admitted to hospital with P falciparum malaria. METHODS In this prospective, multicentre observational study, we analysed admissions to six tertiary care hospitals in The Gambia, Malawi, Gabon, Kenya, and Ghana that participated in the Severe Malaria in African Children network. Patients were enrolled if they were younger than 180 months and had a Giemsa-stained thick blood smear that was positive for P falciparum. Blood transfusion (whole blood at a target volume of 20 mL per kg) was administered at the discretion of the responsible physicians who were aware of local and international transfusion guidelines. The primary endpoint was death associated with transfusion, which was estimated using models adjusted for site and disease severity. We also aimed to identify factors associated with the decision to transfuse. The exploratory objective was to estimate optimal haemoglobin transfusion thresholds using generalised additive models. FINDINGS Between Dec 19, 2000, and March 8, 2005, 26 106 patients were enrolled in the study, 25 893 of whom had their transfusion status recorded and were included in the primary analysis. 8513 (32·8%) patients received a blood transfusion. Patients were followed-up until discharge from hospital for a median of 2 days (IQR 1-4). 405 (4·8%) of 8513 patients who received a transfusion died compared with 689 (4·0%) of 17 380 patients who did not receive a transfusion. Transfusion was associated with decreased odds of death in site-adjusted analysis (odds ratio [OR] 0·82 [95% CI 0·71-0·94]) and after adjusting for the increased disease severity of patients who received a transfusion (0·50 [0·42-0·60]). Severe anaemia, elevated lactate concentration, respiratory distress, and parasite density were associated with greater odds of receiving a transfusion. Among all study participants, transfusion was associated with improved survival when the admission haemoglobin concentration was up to 77 g/L (95% CI 65-110). Among those with impaired consciousness (Blantyre Coma Score ≤4), transfusion was associated with improved survival at haemoglobin concentrations up to 105 g/L (95% CI 71-115). Among those with hyperlactataemia (blood lactate ≥5·0 mmol/L), transfusion was not significantly associated with harm at any haemoglobin concentration-ie, the OR of death comparing transfused versus not transfused was less than 1 at all haemoglobin concentrations (lower bound of the 95% CI for the haemoglobin concentration at which the OR of death equals 1: 90 g/L; no upper bound). INTERPRETATION Our findings suggest that whole blood transfusion was associated with improved survival among children hospitalised with P falciparum malaria. Among those with impaired consciousness or hyperlactataemia, transfusion was associated with improved survival at haemoglobin concentrations above the currently recommended transfusion threshold. These findings highlight the need to do randomised controlled trials to test higher transfusion thresholds among African children with severe malaria complicated by these factors. FUNDING US National Institute of Allergy and Infectious Diseases.
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8
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Malaria in Pregnancy and Adverse Birth Outcomes: New Mechanisms and Therapeutic Opportunities. Trends Parasitol 2019; 36:127-137. [PMID: 31864896 DOI: 10.1016/j.pt.2019.12.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Revised: 11/29/2019] [Accepted: 12/02/2019] [Indexed: 12/28/2022]
Abstract
Malaria infection during pregnancy is associated with adverse birth outcomes but underlying mechanisms are poorly understood. Here, we discuss the impact of malaria in pregnancy on three pathways that are important regulators of healthy pregnancy outcomes: L-arginine-nitric oxide biogenesis, complement activation, and the heme axis. These pathways are not mutually exclusive, and they collectively create a proinflammatory, antiangiogenic milieu at the maternal-fetal interface that interferes with placental function and development. We hypothesize that targeting these host-response pathways would mitigate the burden of adverse birth outcomes attributable to malaria in pregnancy.
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Erice C, Kain KC. New insights into microvascular injury to inform enhanced diagnostics and therapeutics for severe malaria. Virulence 2019; 10:1034-1046. [PMID: 31775570 PMCID: PMC6930010 DOI: 10.1080/21505594.2019.1696621] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Revised: 11/05/2019] [Accepted: 11/13/2019] [Indexed: 12/25/2022] Open
Abstract
Severe malaria (SM) has high mortality and morbidity rates despite treatment with potent antimalarials. Disease onset and outcome is dependent upon both parasite and host factors. Infected erythrocytes bind to host endothelium contributing to microvascular occlusion and dysregulated inflammatory and immune host responses, resulting in endothelial activation and microvascular damage. This review focuses on the mechanisms of host endothelial and microvascular injury. Only a small percentage of malaria infections (≤1%) progress to SM. Early recognition and treatment of SM can improve outcome, but we lack triage tools to identify SM early in the course of infection. Current point-of-care pathogen-based rapid diagnostic tests do not address this critical barrier. Immune and endothelial activation have been implicated in the pathobiology of SM. We hypothesize that measuring circulating mediators of these pathways at first clinical presentation will enable early triage and treatment of SM. Moreover, that host-based interventions that modulate these pathways will stabilize the microvasculature and improve clinical outcome over that of antimalarial therapy alone.
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Affiliation(s)
- Clara Erice
- Sandra-Rotman Centre for Global Health, Toronto General Research Institute, University Health Network-Toronto General Hospital, Toronto, Ontario, Canada
| | - Kevin C Kain
- Sandra-Rotman Centre for Global Health, Toronto General Research Institute, University Health Network-Toronto General Hospital, Toronto, Ontario, Canada
- Tropical Disease Unit, Division of Infectious Diseases, Department of Medicine, University of Toronto, Toronto, Canada
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10
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Changes in monocyte subsets are associated with clinical outcomes in severe malarial anaemia and cerebral malaria. Sci Rep 2019; 9:17545. [PMID: 31772386 PMCID: PMC6879635 DOI: 10.1038/s41598-019-52579-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Accepted: 10/18/2019] [Indexed: 01/17/2023] Open
Abstract
Monocytes are plastic heterogeneous immune cells involved in host-parasite interactions critical for malaria pathogenesis. Human monocytes have been subdivided into three populations based on surface expression of CD14 and CD16. We hypothesised that proportions and phenotypes of circulating monocyte subsets can be markers of severity or fatality in children with malaria. To address this question, we compared monocytes sampled in children with uncomplicated malaria, severe malarial anaemia, or cerebral malaria. Flow cytometry was used to distinguish and phenotype monocyte subsets through CD14, CD16, CD36 and TLR2 expression. Data were first analysed by univariate analysis to evaluate their link to severity and death. Second, multinomial logistic regression was used to measure the specific effect of monocyte proportions and phenotypes on severity and death, after adjustments for other variables unrelated to monocytes. Multivariate analysis demonstrated that decreased percentages of non-classical monocytes were associated with death, suggesting that this monocyte subset has a role in resolving malaria. Using univariate analysis, we also showed that the role of non-classical monocytes involves a mostly anti-inflammatory profile and the expression of CD16. Further studies are needed to decipher the functions of this sub-population during severe malaria episodes, and understand the underlying mechanisms.
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11
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Gomes AC, Moreira AC, Mesquita G, Gomes MS. Modulation of Iron Metabolism in Response to Infection: Twists for All Tastes. Pharmaceuticals (Basel) 2018; 11:ph11030084. [PMID: 30200471 PMCID: PMC6161156 DOI: 10.3390/ph11030084] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Revised: 08/27/2018] [Accepted: 08/28/2018] [Indexed: 12/21/2022] Open
Abstract
Iron is an essential nutrient for almost all living organisms, but is not easily made available. Hosts and pathogens engage in a fight for the metal during an infection, leading to major alterations in the host’s iron metabolism. Important pathological consequences can emerge from the mentioned interaction, including anemia. Several recent reports have highlighted the alterations in iron metabolism caused by different types of infection, and several possible therapeutic strategies emerge, based on the targeting of the host’s iron metabolism. Here, we review the most recent literature on iron metabolism alterations that are induced by infection, the consequent development of anemia, and the potential therapeutic approaches to modulate iron metabolism in order to correct iron-related pathologies and control the ongoing infection.
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Affiliation(s)
- Ana Cordeiro Gomes
- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, 4200-135 Porto, Portugal.
- Instituto de Biologia Molecular e Celular, Universidade do Porto, 4200-135 Porto, Portugal.
| | - Ana C Moreira
- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, 4200-135 Porto, Portugal.
- Instituto de Biologia Molecular e Celular, Universidade do Porto, 4200-135 Porto, Portugal.
| | - Gonçalo Mesquita
- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, 4200-135 Porto, Portugal.
- Instituto de Biologia Molecular e Celular, Universidade do Porto, 4200-135 Porto, Portugal.
| | - Maria Salomé Gomes
- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, 4200-135 Porto, Portugal.
- Instituto de Biologia Molecular e Celular, Universidade do Porto, 4200-135 Porto, Portugal.
- Instituto de Ciências Biomédicas de Abel Salazar, Universidade do Porto, 4050-313 Porto, Portugal.
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12
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Conroy AL, Hawkes MT, Elphinstone R, Opoka RO, Namasopo S, Miller C, John CC, Kain KC. Chitinase-3-like 1 is a biomarker of acute kidney injury and mortality in paediatric severe malaria. Malar J 2018; 17:82. [PMID: 29448936 PMCID: PMC5815237 DOI: 10.1186/s12936-018-2225-5] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2018] [Accepted: 02/07/2018] [Indexed: 12/16/2022] Open
Abstract
Background Chitinase-3-like 1 (CHI3L1) is a glycoprotein elevated in paediatric severe malaria, and an emerging urinary biomarker of acute kidney injury (AKI). Based on the hypothesis that elevated CHI3L1 levels in malaria are associated with disease severity, the relationship between plasma CHI3L1 levels, AKI and mortality was investigated in Ugandan children enrolled in a clinical trial evaluating inhaled nitric oxide (iNO) as an adjunctive therapy for severe malaria. Methods Plasma CHI3L1 levels were measured daily for 4 days in children admitted to hospital with severe malaria and at day 14 follow up. AKI was defined using the Kidney Disease: Improving Global Outcomes consensus criteria. This is a secondary analysis of a randomized double-blind placebo-controlled trial of iNO versus placebo as an adjunctive therapy for severe malaria. Inclusion criteria were: age 1–10 years, and selected criteria for severe malaria. Exclusion criteria included suspected bacterial meningitis, known chronic illness including renal disease, haemoglobinopathy, or severe malnutrition. iNO was administered by non-rebreather mask for up to 72 h at 80 ppm. Results CHI3L1 was elevated in patients with AKI and remained higher over hospitalization (p < 0.0001). Admission CHI3L1 levels were elevated in children who died. By multivariable analysis logCHI3L1 levels were associated with increased risk of in-hospital death (relative risk, 95% CI 4.10, 1.32–12.75, p = 0.015) and all-cause 6 month mortality (3.21, 1.47–6.98, p = 0.003) following correction for iNO and AKI. Treatment with iNO was associated with delayed CHI3L1 recovery with a daily decline of 34% in the placebo group versus 29% in the iNO group (p = 0.012). CHI3L1 levels correlated with markers of inflammation (CRP, sTREM-1, CXCL10), endothelial activation (Ang-2, sICAM-1) and intravascular haemolysis (LDH, haem, haemopexin). Conclusions CHI3L1 is a novel biomarker of malaria-associated AKI and an independent risk factor for mortality that is associated with well-established pathways of severe malaria pathogenesis including inflammation, endothelial activation, and haemolysis. Trial registration Clinicaltrials.gov, NCT01255215. Registered December 7th 2010 Electronic supplementary material The online version of this article (10.1186/s12936-018-2225-5) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Andrea L Conroy
- Department of Pediatrics, Indiana University School of Medicine, 1044 West Walnut St., Building 4, Indianapolis, IN, 46202, USA. .,Sandra Rotman Centre for Global Health, Toronto General Hospital, University Health Network, MaRS Centre, 101 College St. TMDT 10-360A, Toronto, ON, M5G 1L7, Canada. .,Division of Infectious Diseases, Department of Medicine, University of Toronto, Toronto, ON, Canada.
| | - Michael T Hawkes
- Division of Pediatric Infectious Diseases, 3-593 Edmonton Clinic Health Academy, University of Alberta, Edmonton, AB, T6G1C9, Canada
| | - Robyn Elphinstone
- Sandra Rotman Centre for Global Health, Toronto General Hospital, University Health Network, MaRS Centre, 101 College St. TMDT 10-360A, Toronto, ON, M5G 1L7, Canada
| | - Robert O Opoka
- Department of Pediatrics and Child Health, Makerere University, Kampala, Uganda
| | - Sophie Namasopo
- Department of Pediatrics, Jinja Regional Referral Hospital, P.O. Box 43, Jinja, Uganda
| | | | - Chandy C John
- Department of Pediatrics, Indiana University School of Medicine, 1044 West Walnut St., Building 4, Indianapolis, IN, 46202, USA
| | - Kevin C Kain
- Sandra Rotman Centre for Global Health, Toronto General Hospital, University Health Network, MaRS Centre, 101 College St. TMDT 10-360A, Toronto, ON, M5G 1L7, Canada.,Division of Infectious Diseases, Department of Medicine, University of Toronto, Toronto, ON, Canada
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13
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Varo R, Crowley VM, Sitoe A, Madrid L, Serghides L, Kain KC, Bassat Q. Adjunctive therapy for severe malaria: a review and critical appraisal. Malar J 2018; 17:47. [PMID: 29361945 PMCID: PMC5781278 DOI: 10.1186/s12936-018-2195-7] [Citation(s) in RCA: 58] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2017] [Accepted: 01/19/2018] [Indexed: 01/22/2023] Open
Abstract
BACKGROUND Despite recent efforts and successes in reducing the malaria burden globally, this infection still accounts for an estimated 212 million clinical cases, 2 million severe malaria cases, and approximately 429,000 deaths annually. Even with the routine use of effective anti-malarial drugs, the case fatality rate for severe malaria remains unacceptably high, with cerebral malaria being one of the most life-threatening complications. Up to one-third of cerebral malaria survivors are left with long-term cognitive and neurological deficits. From a population point of view, the decrease of malaria transmission may jeopardize the development of naturally acquired immunity against the infection, leading to fewer total cases, but potentially an increase in severe cases. The pathophysiology of severe and cerebral malaria is not completely understood, but both parasite and host determinants contribute to its onset and outcomes. Adjunctive therapy, based on modulating the host response to infection, could help to improve the outcomes achieved with specific anti-malarial therapy. RESULTS AND CONCLUSIONS In the last decades, several interventions targeting different pathways have been tested. However, none of these strategies have demonstrated clear beneficial effects, and some have shown deleterious outcomes. This review aims to summarize evidence from clinical trials testing different adjunctive therapy for severe and cerebral malaria in humans. It also highlights some preclinical studies which have evaluated novel strategies and other candidate therapeutics that may be evaluated in future clinical trials.
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Affiliation(s)
- Rosauro Varo
- Centro de Investigação em Saúde de Manhiça, Rua 12, vila da Manhiça, 1929, Maputo, Mozambique.
- ISGlobal, Barcelona Institute for Global Health, Hospital Clínic, Universitat de Barcelona, Rosselló 132, 5th Floor, 08036, Barcelona, Spain.
| | - Valerie M Crowley
- S. A. Rotman Laboratories, Sandra Rotman Centre for Global Health, University Health Network-Toronto General Hospital, Toronto, Canada
| | - Antonio Sitoe
- Centro de Investigação em Saúde de Manhiça, Rua 12, vila da Manhiça, 1929, Maputo, Mozambique
| | - Lola Madrid
- Centro de Investigação em Saúde de Manhiça, Rua 12, vila da Manhiça, 1929, Maputo, Mozambique
- ISGlobal, Barcelona Institute for Global Health, Hospital Clínic, Universitat de Barcelona, Rosselló 132, 5th Floor, 08036, Barcelona, Spain
| | - Lena Serghides
- Toronto General Research Institute (TGRI), University Health Network, Toronto, Canada
- Women's College Research Institute, Women's College Hospital, Toronto, Canada
- Department of Immunology and Institute of Medical Sciences, University of Toronto, Toronto, Canada
| | - Kevin C Kain
- S. A. Rotman Laboratories, Sandra Rotman Centre for Global Health, University Health Network-Toronto General Hospital, Toronto, Canada
- Department of Medicine, University of Toronto, Toronto, ON, Canada
- Tropical Diseases Unit, Division of Infectious Diseases, Department of Medicine, UHN-Toronto General Hospital, Toronto, ON, Canada
| | - Quique Bassat
- Centro de Investigação em Saúde de Manhiça, Rua 12, vila da Manhiça, 1929, Maputo, Mozambique.
- ISGlobal, Barcelona Institute for Global Health, Hospital Clínic, Universitat de Barcelona, Rosselló 132, 5th Floor, 08036, Barcelona, Spain.
- ICREA, Pg. Lluís Companys 23, 08010, Barcelona, Spain.
- Pediatric Infectious Diseases Unit, Pediatrics Department, Hospital Sant Joan de Déu (University of Barcelona), Barcelona, Spain.
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14
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Crowley VM, Ayi K, Lu Z, Liby KT, Sporn M, Kain KC. Synthetic oleanane triterpenoids enhance blood brain barrier integrity and improve survival in experimental cerebral malaria. Malar J 2017; 16:463. [PMID: 29137631 PMCID: PMC5686938 DOI: 10.1186/s12936-017-2109-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2017] [Accepted: 11/04/2017] [Indexed: 12/31/2022] Open
Abstract
Background Cerebral malaria (CM) is a severe complication of Plasmodium falciparum infection associated with high mortality and neurocognitive impairment in survivors. New anti-malarials and host-based adjunctive therapy may improve clinical outcome in CM. Synthetic oleanane triterpenoid (SO) compounds have shown efficacy in the treatment of diseases where inflammation and oxidative stress contribute to pathogenesis. Methods A derivative of the SO 2-cyano-3,12-dioxooleana-1,9-dien-28-oic acid (CDDO), CDDO-ethyl amide (CDDO-EA) was investigated for the treatment of severe malaria in a pre-clinical model. CDDO-EA was evaluated in vivo as a monotherapy as well as adjunctive therapy with parenteral artesunate in the Plasmodium berghei strain ANKA experimental cerebral malaria (ECM) model. Results CDDO-EA alone improved outcome in ECM and, given as adjunctive therapy in combination with artesunate, it significantly improved outcome over artesunate alone (p = 0.009). Improved survival was associated with reduced inflammation, enhanced endothelial stability and blood–brain barrier integrity. Survival was improved even when administered late in the disease course after the onset of neurological symptoms. Conclusions These results indicate that SO are a new class of immunomodulatory drugs and support further studies investigating this class of agents as potential adjunctive therapy for severe malaria.
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Affiliation(s)
- Valerie M Crowley
- S. A. Rotman Laboratories, Sandra Rotman Centre for Global Health, University Health Network-Toronto General Hospital, Toronto, Canada
| | - Kodjo Ayi
- S. A. Rotman Laboratories, Sandra Rotman Centre for Global Health, University Health Network-Toronto General Hospital, Toronto, Canada
| | - Ziyue Lu
- S. A. Rotman Laboratories, Sandra Rotman Centre for Global Health, University Health Network-Toronto General Hospital, Toronto, Canada
| | - Karen T Liby
- Department of Pharmacology, Dartmouth Medical School, Hanover, NH, USA
| | - Michael Sporn
- Department of Pharmacology, Dartmouth Medical School, Hanover, NH, USA
| | - Kevin C Kain
- S. A. Rotman Laboratories, Sandra Rotman Centre for Global Health, University Health Network-Toronto General Hospital, Toronto, Canada. .,Department of Medicine, University of Toronto, Toronto, ON, Canada. .,Tropical Diseases Unit, Division of Infectious Diseases, Department of Medicine, UHN-Toronto General Hospital, Toronto, ON, Canada.
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15
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Hahl P, Hunt R, Bjes ES, Skaff A, Keightley A, Smith A. Identification of oxidative modifications of hemopexin and their predicted physiological relevance. J Biol Chem 2017; 292:13658-13671. [PMID: 28596380 DOI: 10.1074/jbc.m117.783951] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Revised: 06/07/2017] [Indexed: 12/26/2022] Open
Abstract
Hemopexin protects against heme toxicity in hemolytic diseases and conditions, sepsis, and sickle cell disease. This protection is sustained by heme-hemopexin complexes in biological fluids that resist oxidative damage during heme-driven inflammation. However, apo-hemopexin is vulnerable to inactivation by reactive nitrogen (RNS) and oxygen species (ROS) that covalently modify amino acids. The resultant nitration of amino acids is considered a specific effect reflecting biological events. Using LC-MS, we discovered low endogenous levels of tyrosine nitration in the peptide YYCFQGNQFLR in the heme-binding site of human hemopexin, which was similarly nitrated in rabbit and rat hemopexins. Immunoblotting and selective reaction monitoring were used to quantify tyrosine nitration of in vivo samples and when hemopexin was incubated in vitro with nitrating nitrite/myeloperoxidase/glucose oxidase. Significantly, heme binding by hemopexin declined as tyrosine nitration proceeded in vitro Three nitrated tyrosines reside in the heme-binding site of hemopexin, and we found that one, Tyr-199, interacts directly with the heme ring D propionate. Investigating the oxidative modifications of amino acids after incubation with tert-butyl hydroperoxide and hypochlorous acid in vitro, we identified additional covalent oxidative modifications on four tyrosine residues and one tryptophan residue of hemopexin. Importantly, three of the four modified tyrosines, some of which have more than one modification, cluster in the heme-binding site, supporting a hierarchy of vulnerable amino acids. We propose that during inflammation, apo-hemopexin is nitrated and oxidated in niches of the body containing activated RNS- and ROS-generating immune and endothelial cells, potentially impairing hemopexin's protective extracellular antioxidant function.
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Affiliation(s)
- Peter Hahl
- From the Department of Molecular Biology and Biochemistry, School of Biological Sciences, University of Missouri-Kansas City, Kansas City, Missouri 64110-2239
| | - Rachel Hunt
- From the Department of Molecular Biology and Biochemistry, School of Biological Sciences, University of Missouri-Kansas City, Kansas City, Missouri 64110-2239
| | - Edward S Bjes
- From the Department of Molecular Biology and Biochemistry, School of Biological Sciences, University of Missouri-Kansas City, Kansas City, Missouri 64110-2239
| | - Andrew Skaff
- From the Department of Molecular Biology and Biochemistry, School of Biological Sciences, University of Missouri-Kansas City, Kansas City, Missouri 64110-2239
| | - Andrew Keightley
- From the Department of Molecular Biology and Biochemistry, School of Biological Sciences, University of Missouri-Kansas City, Kansas City, Missouri 64110-2239
| | - Ann Smith
- From the Department of Molecular Biology and Biochemistry, School of Biological Sciences, University of Missouri-Kansas City, Kansas City, Missouri 64110-2239
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16
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Elphinstone RE, Conroy AL, Hawkes M, Hermann L, Namasopo S, Warren HS, John CC, Liles WC, Kain KC. Alterations in Systemic Extracellular Heme and Hemopexin Are Associated With Adverse Clinical Outcomes in Ugandan Children With Severe Malaria. J Infect Dis 2016; 214:1268-75. [PMID: 27515862 PMCID: PMC5034960 DOI: 10.1093/infdis/jiw357] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2016] [Accepted: 08/01/2016] [Indexed: 12/23/2022] Open
Abstract
Background. Malaria remains a major cause of global mortality. Extracellular heme, released during malaria-induced hemolysis, mediates a number of pathogenic processes associated with vascular and organ injury. Hemopexin (hpx) facilitates the degradation of extracellular heme. In this study, we explore the hypothesis that dysregulation of the heme-hpx axis is associated with disease severity, acute kidney injury (AKI), and outcome. Methods. Plasma levels of hemin and hpx (at admission, day 3, and day 14) were assessed in children with severe malaria in Jinja, Uganda. Results. The ratio of heme to hpx was higher at admission and decreased with recovery (median, 0.043 [interquartile range {IQR}, 0.007–0.239] on day 1, 0.024 [IQR, 0.005–0.126] on day 3, and 0.008 [IQR, 0.002–0.022] on day 14; P < .001). Ratios of heme to hpx at admission were higher in children with as compared to those without severe anemia (median, 0.124 [IQR, 0.024–0.431] vs 0.016 [IQR, 0.003–0.073]; P < .0001), children with as compared to those without respiratory distress (median, 0.063 [IQR, 0.017–0.413] vs 0.020 [IQR, 0.004–0.124]; P < .01), and children with as opposed to those without stage 3 AKI (median, 0.354 [IQR, 0.123–2.481] vs 0.037 [IQR, 0.005–0.172], P < .01). The heme to hpx ratio at admission was associated with 6-month mortality (median, 0.148 [IQR, 0.042–0.500] vs 0.039 [IQR, 0.007–0.172]; P = .012). Conclusions. The ratio of heme to hpx is associated with disease severity and adverse clinical outcomes in Ugandan children, and dysregulation of the heme axis may contribute to malaria pathogenesis.
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Affiliation(s)
- Robyn E Elphinstone
- Sandra Rotman Centre for Global Health, University Health Network-Toronto General Hospital Department of Laboratory Medicine and Pathobiology
| | - Andrea L Conroy
- Sandra Rotman Centre for Global Health, University Health Network-Toronto General Hospital Department of Pediatrics, Indiana University, Indianapolis
| | - Michael Hawkes
- Sandra Rotman Centre for Global Health, University Health Network-Toronto General Hospital Division of Pediatric Infectious Diseases, University of Alberta, Edmonton, Canada
| | - Laura Hermann
- Sandra Rotman Centre for Global Health, University Health Network-Toronto General Hospital
| | - Sophie Namasopo
- Department of Pediatrics, Jinja Regional Referral Hospital, Uganda
| | - H Shaw Warren
- Infectious Disease Unit, Department of Pediatrics, Massachusetts General Hospital, Boston
| | - Chandy C John
- Department of Pediatrics, Indiana University, Indianapolis
| | - W Conrad Liles
- Department of Medicine, University of Washington, Seattle
| | - Kevin C Kain
- Sandra Rotman Centre for Global Health, University Health Network-Toronto General Hospital Department of Laboratory Medicine and Pathobiology Tropical Disease Unit, Division of Infectious Diseases, Department of Medicine, University of Toronto
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17
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Conroy AL, Hawkes M, McDonald CR, Kim H, Higgins SJ, Barker KR, Namasopo S, Opoka RO, John CC, Liles WC, Kain KC. Host Biomarkers Are Associated With Response to Therapy and Long-Term Mortality in Pediatric Severe Malaria. Open Forum Infect Dis 2016; 3:ofw134. [PMID: 27703996 PMCID: PMC5047396 DOI: 10.1093/ofid/ofw134] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Accepted: 06/16/2016] [Indexed: 11/13/2022] Open
Abstract
Background. Host responses to infection are critical determinants of disease severity and clinical outcome. The development of tools to risk stratify children with malaria is needed to identify children most likely to benefit from targeted interventions. Methods. This study investigated the kinetics of candidate biomarkers of mortality associated with endothelial activation and dysfunction (angiopoietin-2 [Ang-2], soluble FMS-like tyrosine kinase-1 [sFlt-1], and soluble intercellular adhesion molecule-1 [sICAM-1]) and inflammation (10 kDa interferon γ-induced protein [CXCL10/IP-10] and soluble triggering receptor expressed on myeloid cells-1 [sTREM-1]) in the context of a randomized, double-blind, placebo-controlled, parallel-arm trial evaluating inhaled nitric oxide versus placebo as adjunctive therapy to parenteral artesunate for severe malaria. One hundred eighty children aged 1-10 years were enrolled at Jinja Regional Referral Hospital in Uganda and followed for up to 6 months. Results. There were no differences between the 2 study arms in the rate of biomarker recovery. Median levels of Ang-2, CXCL10, and sFlt-1 were higher at admission in children who died in-hospital (n = 15 of 180; P < .001, P = .027, and P = .004, respectively). Elevated levels of Ang-2, sTREM-1, CXCL10, and sICAM-1 were associated with prolonged clinical recovery times in survivors. The Ang-2 levels were also associated with postdischarge mortality (P < .0001). No biomarkers were associated with neurodisability. Conclusions. Persistent endothelial activation and dysfunction predict survival in children admitted with severe malaria.
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Affiliation(s)
- Andrea L Conroy
- Sandra A. Rotman Laboratories, Sandra Rotman Centre for Global Health, University Health Network-Toronto General Hospital, University of Toronto, Canada; Department of Pediatrics, Indiana University School of Medicine, Indianapolis
| | - Michael Hawkes
- Sandra A. Rotman Laboratories, Sandra Rotman Centre for Global Health, University Health Network-Toronto General Hospital, University of Toronto, Canada; Division of Pediatric Infectious Diseases, University of Alberta, Edmonton, Canada
| | - Chloe R McDonald
- Sandra A. Rotman Laboratories, Sandra Rotman Centre for Global Health , University Health Network-Toronto General Hospital, University of Toronto , Canada
| | - Hani Kim
- Sandra A. Rotman Laboratories, Sandra Rotman Centre for Global Health , University Health Network-Toronto General Hospital, University of Toronto , Canada
| | - Sarah J Higgins
- Sandra A. Rotman Laboratories, Sandra Rotman Centre for Global Health , University Health Network-Toronto General Hospital, University of Toronto , Canada
| | - Kevin R Barker
- Sandra A. Rotman Laboratories, Sandra Rotman Centre for Global Health , University Health Network-Toronto General Hospital, University of Toronto , Canada
| | | | - Robert O Opoka
- Department of Paediatrics and Child Health , Mulago Hospital and Makerere University , Kampala , Uganda
| | - Chandy C John
- Department of Pediatrics , Indiana University School of Medicine , Indianapolis
| | - W Conrad Liles
- Department of Medicine , University of Washington , Seattle
| | - Kevin C Kain
- Sandra A. Rotman Laboratories, Sandra Rotman Centre for Global Health, University Health Network-Toronto General Hospital, University of Toronto, Canada; Tropical Disease Unit, Division of Infectious Diseases, Department of Medicine, University of Toronto, Canada
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