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Lowe M, Bambhroliya Z, Patel H, Patel VJ, Vudugula SA, Cheruvu NP, Raza S, Okunlola OI. Emerging Therapies for the Management of Pain and Vaso-Occlusive Crises in Patients With Sickle Cell Disease: A Systematic Review of Randomized Controlled Trials. Cureus 2023; 15:e38014. [PMID: 37223201 PMCID: PMC10204617 DOI: 10.7759/cureus.38014] [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: 04/23/2023] [Indexed: 05/25/2023] Open
Abstract
Sickle cell disease (SCD) is an inherited disorder that impairs red blood cells (RBCs) and disrupts the delivery of oxygen to tissues. There is currently no cure. Symptoms can appear as early as six months of age and include anemia, acute episodes of pain, swelling, infections, delayed growth, and vision problems. A growing number of therapies are being investigated for reducing these episodes of pain, also known as vaso-occlusive crises (VOCs). The research literature evidence, however, currently includes far more approaches that have not shown superiority versus placebo than ones that have been proven effective. The purpose of this systematic review is to evaluate the body of randomized controlled trials (RCTs) to determine the quality of support for and against the use of a variety of current and emerging therapies for treading SCD VOCs. Several important new papers have emerged since previous systematic reviews with similar objectives were published. This review was conducted according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines and focused on PubMed exclusively. Only RCTs were sought, and no other filters, except for a five-year historical timeline cut-off, were used. Of the 46 publications that were returned in response to the query, 18 were ultimately accepted as meeting the pre-established inclusion criteria. The Cochrane risk-of-bias tool was utilized as a quality assessment measure, and the GRADE (Grading of Recommendations, Assessment, Development, and Evaluations) framework was used to assess the certainty of the evidence. Among the included publications, five out of 18 featured positive results with superiority and statistical significance versus placebo for either reduction in pain score or number/duration of VOCs. The approaches featured therapies ranging from de novo molecules to currently available drugs approved for other indications to naturally occurring metabolites such as amino acids and vitamins. A single therapy, arginine, was supported for both clinical endpoints: pain score reduction and shortened VOC duration. Currently, two therapies are approved by the United States Food and Drug Administration (FDA) and are commercially available (crizanlizumab, ADAKVEO and L-glutamine, Endari). All other therapies are investigational only in nature. Several studies included measurement of biomarker endpoints as well as clinical outcomes. Generally, beneficial outcomes related to improving biomarker levels did not also translate into statistically significant reduction of pain scores or number/duration of VOCs. While measuring biomarkers may contribute to the understanding of pathophysiology, it does not appear to directly offer predictive value toward treatment success clinically. It can be concluded that there exists a specific opportunity to design, fund, and execute investigations that both compare emerging and existing therapies versus one another and compare combinational therapies versus placebo.
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Affiliation(s)
- Michael Lowe
- Seeking Anesthesiology, Ross University School of Medicine, Fort Lauderdale, USA
| | - Zarna Bambhroliya
- Research, California Institute of Behavioral Neurosciences & Psychology, Fairfield, USA
| | - Hesha Patel
- Internal Medicine, Capital Health Medical Center, New Jersey, USA
| | - Vishva J Patel
- Medicine, Gujarat Medical Education and Research Society (GMERS) Medical College, Vadodara, IND
| | | | | | - Shafaat Raza
- Medicine, California Institute of Behavioral Neurosciences & Psychology, Fairfield, USA
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Lampro L, George EC. Outcomes reported in trials of treatments for severe malaria: The need for a core outcome set. Trop Med Int Health 2022; 27:767-775. [PMID: 35916146 PMCID: PMC9545330 DOI: 10.1111/tmi.13803] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
OBJECTIVES Malaria is one of the most important parasitic infectious diseases worldwide. Despite the scale-up of effective antimalarials, mortality rates from severe malaria (SM) remain significantly high; thus, numerous trials are investigating both antimalarials and adjunctive therapy. This review aimed to summarise all the outcome measures used in trials in the last 10 years to see the need for a core outcome set. METHODS A systematic review was undertaken to summarise outcomes of individually randomised trials assessing treatments for SM in adults and children. We searched key databases and trial registries between 1 January 2010 and 30 July 2020. Non-randomised trials were excluded to allow comparison of similar trials. Trial characteristics including phase, region, population, interventions, were summarised. All primary and secondary outcomes were extracted and categorised using a taxonomy table. RESULTS Twenty-seven of 282 screened trials met our inclusion criteria, including 10,342 patients from 19 countries: 19 (70%) trials from Africa and 8 (30%) from Asia. A large amount of heterogeneity was observed in the selection of outcomes and instruments, with 101 different outcomes measures recorded, 78/101 reported only in a single trial. Parasitological outcomes (17 studies), neurological status (14 studies), death (14 studies) and temperature (10 studies), were the most reported outcomes. Where an outcome was reported in >1 study it was often measured differently: temperature (4 different measures), renal function (7 measures), nervous system (13 measures) and parasitology (10 measures). CONCLUSION Outcomes used in SM trials are inconsistent and heterogeneous. Absence of consensus for outcome measures used impedes research synthesis and comparability of different interventions. This systematic review demonstrates the need to develop a standardised collection of core outcomes for clinical trials of treatments for SM and next steps to include the development of a panel of experts in the field, a Delphi process, and a consensus meeting.
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Affiliation(s)
- Lamprini Lampro
- Medical Research Council Clinical Trials Unit at University College London, London, UK.,Intensive Care National Audit and Research Centre, London, UK
| | - Elizabeth C George
- Medical Research Council Clinical Trials Unit at University College London, London, UK
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Gomes ARQ, Cunha N, Varela ELP, Brígido HPC, Vale VV, Dolabela MF, de Carvalho EP, Percário S. Oxidative Stress in Malaria: Potential Benefits of Antioxidant Therapy. Int J Mol Sci 2022; 23:ijms23115949. [PMID: 35682626 PMCID: PMC9180384 DOI: 10.3390/ijms23115949] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Revised: 05/17/2022] [Accepted: 05/19/2022] [Indexed: 01/07/2023] Open
Abstract
Malaria is an infectious disease and a serious public health problem in the world, with 3.3 billion people in endemic areas in 100 countries and about 200 million new cases each year, resulting in almost 1 million deaths in 2018. Although studies look for strategies to eradicate malaria, it is necessary to know more about its pathophysiology to understand the underlying mechanisms involved, particularly the redox balance, to guarantee success in combating this disease. In this review, we addressed the involvement of oxidative stress in malaria and the potential benefits of antioxidant supplementation as an adjuvant antimalarial therapy.
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Affiliation(s)
- Antonio Rafael Quadros Gomes
- Post-Graduate Program in Pharmaceutica Innovation, Institute of Health Sciences, Federal University of Pará, Belém 66075-110, PA, Brazil; (A.R.Q.G.); (H.P.C.B.); (V.V.V.); (M.F.D.)
- Oxidative Stress Research Laboratory, Institute of Biological Sciences, Federal University of Pará, Belém 66075-110, PA, Brazil; (N.C.); (E.L.P.V.); (E.P.d.C.)
| | - Natasha Cunha
- Oxidative Stress Research Laboratory, Institute of Biological Sciences, Federal University of Pará, Belém 66075-110, PA, Brazil; (N.C.); (E.L.P.V.); (E.P.d.C.)
| | - Everton Luiz Pompeu Varela
- Oxidative Stress Research Laboratory, Institute of Biological Sciences, Federal University of Pará, Belém 66075-110, PA, Brazil; (N.C.); (E.L.P.V.); (E.P.d.C.)
- Post-graduate Program in Biodiversity and Biotechnology (BIONORTE), Institute of Biological Sciences, Federal University of Pará, Belém 66075-110, PA, Brazil
| | - Heliton Patrick Cordovil Brígido
- Post-Graduate Program in Pharmaceutica Innovation, Institute of Health Sciences, Federal University of Pará, Belém 66075-110, PA, Brazil; (A.R.Q.G.); (H.P.C.B.); (V.V.V.); (M.F.D.)
| | - Valdicley Vieira Vale
- Post-Graduate Program in Pharmaceutica Innovation, Institute of Health Sciences, Federal University of Pará, Belém 66075-110, PA, Brazil; (A.R.Q.G.); (H.P.C.B.); (V.V.V.); (M.F.D.)
| | - Maria Fâni Dolabela
- Post-Graduate Program in Pharmaceutica Innovation, Institute of Health Sciences, Federal University of Pará, Belém 66075-110, PA, Brazil; (A.R.Q.G.); (H.P.C.B.); (V.V.V.); (M.F.D.)
- Post-graduate Program in Biodiversity and Biotechnology (BIONORTE), Institute of Biological Sciences, Federal University of Pará, Belém 66075-110, PA, Brazil
| | - Eliete Pereira de Carvalho
- Oxidative Stress Research Laboratory, Institute of Biological Sciences, Federal University of Pará, Belém 66075-110, PA, Brazil; (N.C.); (E.L.P.V.); (E.P.d.C.)
- Post-graduate Program in Biodiversity and Biotechnology (BIONORTE), Institute of Biological Sciences, Federal University of Pará, Belém 66075-110, PA, Brazil
| | - Sandro Percário
- Oxidative Stress Research Laboratory, Institute of Biological Sciences, Federal University of Pará, Belém 66075-110, PA, Brazil; (N.C.); (E.L.P.V.); (E.P.d.C.)
- Post-graduate Program in Biodiversity and Biotechnology (BIONORTE), Institute of Biological Sciences, Federal University of Pará, Belém 66075-110, PA, Brazil
- Correspondence:
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The Role of Amino Acids in Endothelial Biology and Function. Cells 2022; 11:cells11081372. [PMID: 35456051 PMCID: PMC9030017 DOI: 10.3390/cells11081372] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Revised: 04/08/2022] [Accepted: 04/16/2022] [Indexed: 12/20/2022] Open
Abstract
The vascular endothelium acts as an important component of the vascular system. It is a barrier between the blood and vessel wall. It plays an important role in regulating blood vessel tone, permeability, angiogenesis, and platelet functions. Several studies have shown that amino acids (AA) are key regulators in maintaining vascular homeostasis by modulating endothelial cell (EC) proliferation, migration, survival, and function. This review summarizes the metabolic and signaling pathways of AAs in ECs and discusses the importance of AA homeostasis in the functioning of ECs and vascular homeostasis. It also discusses the challenges in understanding the role of AA in the development of cardiovascular pathophysiology and possible directions for future research.
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Morris CR, Kuypers FA, Hagar R, Larkin S, Lavrisha L, Saulys A, Vichinsky EP, Suh JH. Implications for the Metabolic Fate of Oral Glutamine Supplementation within Plasma and Erythrocytes of Patients with Sickle Cell Disease: A Pharmacokinetics Study. Complement Ther Med 2022; 64:102803. [PMID: 35032556 DOI: 10.1016/j.ctim.2022.102803] [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] [Received: 12/04/2020] [Revised: 11/13/2021] [Accepted: 01/10/2022] [Indexed: 12/25/2022] Open
Abstract
OBJECTIVES L-Glutamine is FDA-approved for sickle cell disease (SCD), yet the mechanism(s)-of-action are poorly understood. We performed a pharmacokinetics (pK) study to determine the metabolic fate of glutamine supplementation on plasma and erythrocyte amino acids in patients with SCD. DESIGN A pK study was performed where patients with SCD fasting for >8hours received oral L-glutamine (10 grams). Blood was analyzed at baseline, 30/60/90minutes/2/3/4/8 hrs. A standardized diet was administered to all participants at 3 established time-points (after 2/5/7hrs). A subset of patients also had pK studies performed without glutamine supplementation to follow normal diurnal fluctuations in amino acids. SETTING Comprehensive SCD Center in Oakland, California RESULTS: Five patients with SCD were included, three of whom performed pK studies both with and without glutamine supplementation. Average age was 50.6 ± 5.6 years, 60% were female, 40% SS, 60% SC. Plasma glutamine levels increased significantly after oral glutamine supplementation, compared to minimal fluctuations with diet. Plasma glutamine concentration peaked within 30-minutes of ingestion (p=0.01) before decreasing to a plateau by 2-hours that remained higher than baseline by 8hours. Oral glutamine also increased plasma arginine concentration, which peaked by 4-hrs (p=0.03) and remained elevated through 8-hrs. Erythrocyte glutamine levels began to increase by 8-hours, while erythrocyte arginine concentration peaked at 4-hours. CONCLUSIONS Oral glutamine supplementation acutely improved glutamine and arginine bioavailability in both plasma and erythrocytes. This is the first study to demonstrate that glutamine therapy increases arginine bioavailability and may provide insight into shared mechanisms-of-action between these conditionally-essential amino acids.
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Affiliation(s)
- Claudia R Morris
- Department of Pediatrics, Emory University School of Medicine, Atlanta, Georgia, USA; Children's Healthcare of Atlanta, Atlanta, Georgia, USA.
| | - Frans A Kuypers
- Department of Hematology/Oncology, UCSF-Benioff Children's Hospital Oakland, Oakland, CA, USA
| | - Robert Hagar
- Department of Hematology/Oncology, UCSF-Benioff Children's Hospital Oakland, Oakland, CA, USA
| | - Sandra Larkin
- Department of Hematology/Oncology, UCSF-Benioff Children's Hospital Oakland, Oakland, CA, USA
| | - Lisa Lavrisha
- Department of Hematology/Oncology, UCSF-Benioff Children's Hospital Oakland, Oakland, CA, USA
| | - Augusta Saulys
- Department of Emergency Medicine, UCSF-Benioff Children's Hospital Oakland, Oakland, CA, USA
| | - Elliott P Vichinsky
- Department of Hematology/Oncology, UCSF-Benioff Children's Hospital Oakland, Oakland, CA, USA
| | - Jung H Suh
- Department of Hematology/Oncology, UCSF-Benioff Children's Hospital Oakland, Oakland, CA, USA
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Metabolomic Analysis of Diverse Mice Reveals Hepatic Arginase-1 as Source of Plasma Arginase in Plasmodium chabaudi Infection. mBio 2021; 12:e0242421. [PMID: 34607466 PMCID: PMC8546868 DOI: 10.1128/mbio.02424-21] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Infections disrupt host metabolism, but the factors that dictate the nature and magnitude of metabolic change are incompletely characterized. To determine how host metabolism changes in relation to disease severity in murine malaria, we performed plasma metabolomics on eight Plasmodium chabaudi-infected mouse strains with diverse disease phenotypes. We identified plasma metabolic biomarkers for both the nature and severity of different malarial pathologies. A subset of metabolic changes, including plasma arginine depletion, match the plasma metabolomes of human malaria patients, suggesting new connections between pathology and metabolism in human malaria. In our malarial mice, liver damage, which releases hepatic arginase-1 (Arg1) into circulation, correlated with plasma arginine depletion. We confirmed that hepatic Arg1 was the primary source of increased plasma arginase activity in our model, which motivates further investigation of liver damage in human malaria patients. More broadly, our approach shows how leveraging phenotypic diversity can identify and validate relationships between metabolism and the pathophysiology of infectious disease. IMPORTANCE Malaria is a severe and sometimes fatal infectious disease endemic to tropical and subtropical regions. Effective vaccines against malaria-causing Plasmodium parasites remain elusive, and malaria treatments often fail to prevent severe disease. Small molecules that target host metabolism have recently emerged as candidates for therapeutics in malaria and other diseases. However, our limited understanding of how metabolites affect pathophysiology limits our ability to develop new metabolite therapies. By providing a rich data set of metabolite-pathology correlations and by validating one of those correlations, our work is an important step toward harnessing metabolism to mitigate disease. Specifically, we showed that liver damage in P. chabaudi-infected mice releases hepatic arginase-1 into circulation, where it may deplete plasma arginine, a candidate malaria therapeutic that mitigates vascular stress. Our data suggest that liver damage may confound efforts to increase levels of arginine in human malaria patients.
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Onalo R, Cooper P, Cilliers A, Vorster BC, Uche N, Oluseyi OO, Onalo VD, Zubairu Y, Ayodele‐Kehinde AU, Damilare OM, Figueroa J, Morris CR. Randomized control trial of oral arginine therapy for children with sickle cell anemia hospitalized for pain in Nigeria. Am J Hematol 2021; 96:89-97. [PMID: 33075179 DOI: 10.1002/ajh.26028] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Revised: 10/16/2020] [Accepted: 10/17/2020] [Indexed: 12/15/2022]
Abstract
Low arginine bioavailability is associated with vaso-occlusive painful crisis (VOC) severity in sickle cell anemia (SCA) and predicts need for pediatric hospitalization. Intravenous arginine therapy has opioid-sparing effects and was found to significantly decrease pain scores in children hospitalized with SCA-VOC in a phase-two randomized placebo-controlled trial (RCT). Efficacy of oral arginine is unknown. Our objective was to determine the safety and efficacy of oral arginine therapy in Nigerian children with SCA. A double-blind RCT of oral L-arginine-hydrochloride (100 mg/kg TID) was conducted in children with SCA-VOC, aged 5-17 years, hospitalized at two Nigerian sites. The primary outcome measure was analgesic usage, quantified by difference in the mean Analgesic Medication Quantification Scale (MQS). Secondary outcomes included daily pain scores, time-to-crisis-resolution and length-of-hospital-stay. An intention-to-treat analysis was performed. Sixty-eight children (age 5-17 years, mean 10.6 ± 0.4 years; 56% male), were randomized to receive L-arginine (35 patients) or placebo (33 patients). The mean total MQS for the arginine group was 73.4 (95% CI, 62.4-84.3) vs 120.0 (96.7-143.3) for placebo (P < .001). The mean rate of decline in worst pain scores was faster in the arginine arm vs placebo (1.50 [1.23-1.77] vs 1.09 [0.94-1.24] point/d, P = .009). Children receiving arginine had a shorter time-to-crisis-resolution (P = .02), shorter hospital-stay (P = .002) and experienced no serious adverse event. Pain control was more rapid, total analgesic requirement was significantly reduced, and most notably, time-to-crisis-resolution and length-of-hospital-stay were shorter in children with SCA-VOC receiving arginine vs placebo. Given the established safety and low cost, oral arginine is a promising adjuvant therapy for SCA-VOC management.
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Affiliation(s)
- Richard Onalo
- Department of Paediatrics Faculty of Clinical Sciences, University of Abuja Gwagwalada Nigeria
- Department of Paediatrics Faculty of Clinical Sciences, University of the Witwatersrand Johannesburg South Africa
| | - Peter Cooper
- Department of Paediatrics Faculty of Clinical Sciences, University of the Witwatersrand Johannesburg South Africa
| | - Antoinette Cilliers
- Department of Paediatrics Chris Hani Baragwanath Academic Hospital, University of the Witwatersrand Johannesburg South Africa
| | - Barend C. Vorster
- Centre for Human Metabolomics North West University Potchefstroom South Africa
| | - Nnebe‐Agumadu Uche
- Department of Paediatrics Faculty of Clinical Sciences, University of Abuja Gwagwalada Nigeria
| | | | - Victoria D. Onalo
- Emergency Paediatric Pharmacy University of Abuja Teaching Hospital Gwagwalada Nigeria
| | - Yunusa Zubairu
- Emergency Paediatric Pharmacy University of Abuja Teaching Hospital Gwagwalada Nigeria
| | | | | | - Janet Figueroa
- Department of Pediatrics Biostatistical Core, Emory University School of Medicine Atlanta Georgia USA
| | - Claudia R. Morris
- Division of Pediatric Emergency Medicine, Department of Pediatrics Emory University School of Medicine Atlanta Georgia USA
- Childrenʼs Healthcare of Atlanta Atlanta Georgia USA
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Zou Y, Tuo F, Zhang Z, Guo J, Yuan Y, Zhang H, Xu Z, Pan Z, Tang Y, Deng C, Julie N, Wu W, Guo W, Li C, Huang X, Xu Q, Song J, Wang Q. Safety and Efficacy of Adjunctive Therapy With Artesunate in the Treatment of Severe Malaria: A Systematic Review and Meta-Analysis. Front Pharmacol 2020; 11:596697. [PMID: 33343367 PMCID: PMC7748123 DOI: 10.3389/fphar.2020.596697] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Accepted: 10/02/2020] [Indexed: 11/13/2022] Open
Abstract
Objective: The purpose of this meta-analysis of longitudinal studies is to determine the safety and efficacy of artesunate combined with other forms of adjunctive therapies for severe malaria. Methods: Following the PRISMA guidelines, we searched multiple databases with the search terms "artesunate" and "adjunctive therapy" and "severe malaria" in July 2020. If the search showed a randomized controlled trial, the study was included in this meta-analysis. The random-effects model was used to calculate the combined incidence rate and relative risk or risk difference. Results: This meta-analysis included nine longitudinal studies with 724 participants. We found that the mortality rates in the artesunate monotherapy group and the artesunate + adjuvant therapy group are similar (RD = -0.02, 95% confidence interval: -0.06-0.02). The incidence of adverse reactions in the artesunate monotherapy group and the artesunate + adjuvant therapy group was also similar. Conclusion: No significant differences in safety and efficacy were observed between the artesunate monotherapy group and the artesunate + adjuvant therapy group. Higher quality and rigorously designed randomized controlled studies are needed to validate our findings.
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Affiliation(s)
- Yuanyuan Zou
- Artemisinin Research Center, Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Fei Tuo
- Artemisinin Research Center, Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Zhiqi Zhang
- Artemisinin Research Center, Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Jiawen Guo
- Institute of Science and Technology, Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Yueming Yuan
- Artemisinin Research Center, Guangzhou University of Chinese Medicine, Guangzhou, China.,Institute of Science and Technology, Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Hongying Zhang
- Artemisinin Research Center, Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Zhiyong Xu
- Institute of Science and Technology, Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Ziyi Pan
- Artemisinin Research Center, Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Yexiao Tang
- Artemisinin Research Center, Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Changsheng Deng
- Artemisinin Research Center, Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Nadia Julie
- Artemisinin Research Center, Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Wanting Wu
- Artemisinin Research Center, Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Wenfeng Guo
- Artemisinin Research Center, Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Changqing Li
- Artemisinin Research Center, Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Xinan Huang
- Artemisinin Research Center, Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Qin Xu
- Artemisinin Research Center, Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Jianping Song
- Artemisinin Research Center, Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Qi Wang
- Artemisinin Research Center, Guangzhou University of Chinese Medicine, Guangzhou, China
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Abstract
Supplemental arginine has shown promise as a safe therapeutic option to improve endogenous nitric oxide (NO) regulation in cardiovascular diseases associated with endothelial dysfunction. In clinical studies in adults, L-arginine, an endogenous amino acid, was reported to improve cardiovascular function in hypertension, pulmonary hypertension, preeclampsia, angina, and MELAS (mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes) syndrome. L-citrulline, a natural precursor of L-arginine, is more bioavailable than L-arginine because it avoids hepatic first-pass metabolism and has a longer circulation time. Although not yet well-studied, arginine/citrulline has immense therapeutic potential in some life-threatening diseases in children. However, the optimal clinical development of arginine or citrulline in children requires more information about pharmacokinetics and exposure-response relationships at appropriate ages and under relevant disease states. This article summarizes the preclinical and clinical studies of arginine/citrulline in both adults and children, including currently available pharmacokinetic information. The pharmacology of arginine/citrulline is confounded by several patient-specific factors such as variations in baseline arginine/citrulline due to developmental ages and disease states. Currently available pharmacokinetic studies are insufficient to inform the optimal design of clinical studies, especially in children. Successful bench-to-bedside clinical translation of arginine supplementation awaits information from well-designed pharmacokinetic/pharmacodynamic studies, along with pharmacometric approaches.
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L-arginine supplementation and thromboxane synthase inhibition increases cerebral blood flow in experimental cerebral malaria. Sci Rep 2019; 9:13621. [PMID: 31541129 PMCID: PMC6754365 DOI: 10.1038/s41598-019-49855-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Accepted: 08/30/2019] [Indexed: 12/14/2022] Open
Abstract
Cerebral malaria pathogenesis involves vascular dysfunction with low nitric oxide (NO) bioavailability, vasoconstriction and impaired vasodilation, leading to ischemia, tissue hypoxia and ultimately death. Cerebral blood flow (CBF) involves NO and other pathways, including arachidonic acid (AA)-derived metabolites. Here we show that mice with experimental cerebral malaria (ECM) by P. berghei ANKA showed marked decreases in CBF (as assessed by laser speckle contrast imaging - LSCI) and that administration of L-arginine supplementation (50 mg/kg) and/or of the thromboxane synthase inhibitor Ozagrel (100 mg/kg) induced immediate increases in CBF. L-arginine in combination with artesunate (32 mg/kg) induced immediate reversal of brain ischemia in the short-term (1 hour), but the effect subsided after 3 and 6 hours. Neither L-arginine nor Ozagrel reversed blood brain barrier breakdown. Mice with ECM showed brain levels of selected AA-derived metabolites with a vasoconstrictor profile, with increased levels of 8-isoprostanes, 20-HETE and 14,15-DHET, whereas mice infected with a non-ECM-inducing strain of P. berghei (NK65) showed a vasodilator profile, with normal levels of 20-HETE and 14,15-DHET and increased levels of PGE2. L-arginine is capable of partially reversing cerebral ischemia and AA metabolites may play a role in the cerebrovascular dysfunction in ECM.
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Kinetic and Cross-Sectional Studies on the Genesis of Hypoargininemia in Severe Pediatric Plasmodium falciparum Malaria. Infect Immun 2019; 87:IAI.00655-18. [PMID: 30718287 DOI: 10.1128/iai.00655-18] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2018] [Accepted: 01/05/2019] [Indexed: 12/12/2022] Open
Abstract
The low bioavailability of nitric oxide (NO) and its precursor, arginine, contributes to the microvascular pathophysiology of severe falciparum malaria. To better characterize the mechanisms underlying hypoargininemia in severe malaria, we measured the plasma concentrations of amino acids involved in de novo arginine synthesis in children with uncomplicated falciparum malaria (UM; n = 61), children with cerebral falciparum malaria (CM; n = 45), and healthy children (HC; n = 109). We also administered primed infusions of l-arginine uniformly labeled with 13C6 and 15N4 to 8 children with severe falciparum malaria (SM; age range, 4 to 9 years) and 7 healthy children (HC; age range, 4 to 8 years) to measure the metabolic flux of arginine, hypothesizing that arginine flux is increased in SM. Using two different tandem mass spectrometric methods, we measured the isotopic enrichment of arginine in plasma obtained at 0, 60, 90, 120, 150, and 180 min during the infusion. The plasma concentrations of glutamine, glutamate, proline, ornithine, citrulline, and arginine were significantly lower in UM and CM than in HC (P ≤ 0.04 for all pairwise comparisons). Of these, glutamine concentrations were the most markedly decreased: median, 457 μM (interquartile range [IQR], 400 to 508 μM) in HC, 300 μM (IQR, 256 to 365 μM) in UM, and 257 μM (IQR, 195 to 320 μM) in CM. Arginine flux during steady state was not significantly different in SM than in HC by the respective mass spectrometric methods: 93.2 μmol/h/kg of body weight (IQR, 84.4 to 129.3 μmol/h/kg) versus 88.0 μmol/h/kg (IQR, 73.0 to 102.2 μmol/h/kg) (P = 0.247) by the two mass spectrometric methods in SM and 93.7 μmol/h/kg (IQR, 79.1 to 117.8 μmol/h/kg) versus 81.0 μmol/h/kg (IQR, 75.9 to 88.6 μmol/h/kg) (P = 0.165) by the two mass spectrometric methods in HC. A limited supply of amino acid precursors for arginine synthesis likely contributes to the hypoargininemia and NO insufficiency in falciparum malaria in children.
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Gramaglia I, Velez J, Chang YS, Caparros-Wanderley W, Combes V, Grau G, Stins MF, van der Heyde HC. Citrulline protects mice from experimental cerebral malaria by ameliorating hypoargininemia, urea cycle changes and vascular leak. PLoS One 2019; 14:e0213428. [PMID: 30849122 PMCID: PMC6407779 DOI: 10.1371/journal.pone.0213428] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Accepted: 02/21/2019] [Indexed: 12/18/2022] Open
Abstract
Clinical and model studies indicate that low nitric oxide (NO) bioavailability due in part to profound hypoargininemia contributes to cerebral malaria (CM) pathogenesis. Protection against CM pathogenesis may be achieved by altering the diet before infection with Plasmodium falciparum infection (nutraceutical) or by administering adjunctive therapy that decreases CM mortality (adjunctive therapy). This hypothesis was tested by administering citrulline or arginine in experimental CM (eCM). We report that citrulline injected as prophylaxis immediately post infection (PI) protected virtually all mice by ameliorating (i) hypoargininemia, (ii) urea cycle impairment, and (iii) disruption of blood brain barrier. Citrulline prophylaxis inhibited plasma arginase activity. Parasitemia was similar in citrulline- and vehicle control-groups, indicating that protection from pathogenesis was not due to decreased parasitemia. Both citrulline and arginine administered from day 1 PI in the drinking water significantly protected mice from eCM. These observations collectively indicate that increasing dietary citrulline or arginine decreases eCM mortality. Citrulline injected ip on day 4 PI with quinine-injected ip on day 6 PI partially protected mice from eCM; citrulline plus scavenging of superoxide with pegylated superoxide dismutase and pegylated catalase protected all recipients from eCM. These findings indicate that ameliorating hypoargininemia with citrulline plus superoxide scavenging decreases eCM mortality.
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Affiliation(s)
- Irene Gramaglia
- La Jolla Infectious Disease Institute, San Diego, CA, United States of America
- * E-mail:
| | - Joyce Velez
- La Jolla Infectious Disease Institute, San Diego, CA, United States of America
| | | | | | - Valery Combes
- La Jolla Infectious Disease Institute, San Diego, CA, United States of America
- School of Life Sciences, University of Technology Sydney, Sydney, Australia
| | - Georges Grau
- La Jolla Infectious Disease Institute, San Diego, CA, United States of America
- Vascular Immunology Unit, University of Sydney, Sydney, Australia
| | - Monique F. Stins
- Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, United States of America
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13
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Najjar N, McColl ER, Weckman A, Kain KC, Piquette-Miller M. Dysregulation of solute carrier transporters in malaria-infected pregnant mice. Parasite Immunol 2019; 41:e12614. [PMID: 30703256 DOI: 10.1111/pim.12614] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Revised: 01/24/2019] [Accepted: 01/25/2019] [Indexed: 12/18/2022]
Abstract
AIMS Malaria in pregnancy (MiP) alters the expression of ATP-binding cassette efflux transporters in maternal and foetal tissues, as well as the placenta. Malaria induces oxidative stress, and pregnancy is associated with arginine deficiency. We hypothesized that reducing oxidative stress during MiP by supplementation with L-arginine, a NO precursor, would attenuate transcriptional changes in a second superfamily of transporters, solute carrier (SLC) transporters, and improve pregnancy outcomes. METHODS AND RESULTS Pregnant BALB/c mice receiving L-arginine (1.2%) in water, or water alone, were infected with Plasmodium berghei ANKA on gestational day 13 and sacrificed on gestational day 19. Compared to controls, the mRNA of numerous SLC transporters was downregulated in maternal and foetal tissues, as well as in the placentas of infected mice. While supplementation with L-arginine did improve foetal viability, it did not improve the mRNA expression of oxidative stress markers, transporters nor other indices of foetal and maternal health. Moreover, amino acid uptake transporters were downregulated upon infection, which could potentially contribute to decreased foetal birthweight. CONCLUSIONS Malaria in pregnancy significantly alters the expression of SLC transporters in maternal and foetal tissues as well as the placenta, regardless of L-arginine supplementation. Further studies to investigate methods of reducing oxidative stress in MiP are warranted.
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Affiliation(s)
- Najwa Najjar
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada
| | - Eliza R McColl
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada
| | - Andrea Weckman
- Sandra Rotman Centre for Global Health, University Health Network: Toronto General Hospital, Toronto, Ontario, Canada
| | - Kevin C Kain
- Sandra Rotman Centre for Global Health, University Health Network: Toronto General Hospital, Toronto, Ontario, Canada
| | - Micheline Piquette-Miller
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada
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14
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Corbett Y, D'Alessandro S, Parapini S, Scaccabarozzi D, Kalantari P, Zava S, Giavarini F, Caruso D, Colombo I, Egan TJ, Basilico N. Interplay between Plasmodium falciparum haemozoin and L-arginine: implication for nitric oxide production. Malar J 2018; 17:456. [PMID: 30522493 PMCID: PMC6282336 DOI: 10.1186/s12936-018-2602-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Accepted: 11/29/2018] [Indexed: 01/07/2023] Open
Abstract
Background Plasmodium falciparum haemozoin, a detoxification product of digested haemoglobin from infected erythrocytes, is released into the bloodstream upon schizont rupture and accumulates in leukocytes. High levels of haemozoin correlate with disease severity. Some studies have shown that concentrations of the substrate of inducible nitric oxide synthase (iNOS), l-arginine, as well as nitric oxide are low in patients infected with P. falciparum malaria. The present study investigates, in vitro, the role of P. falciparum haemozoin on nitric oxide production, iNOS expression in macrophages, and the possible interaction between l-arginine and haemozoin. Methods Plasmodium falciparum haemozoin was obtained from in vitro cultures through magnetic isolation. Phagocytosis of haemozoin by immortalized bone marrow derived macrophages was detected by confocal reflection combined with fluorescence microscopy. Nitrite concentrations in the supernatants was evaluated by Griess assay as a standard indication of nitric oxide production, while iNOS expression was detected on cell extracts by western blotting. Detection of l-arginine in haemozoin-treated or untreated media was achieved by liquid chromatography–tandem mass spectrometry (LC–MS/MS). Results Haemozoin synergizes in vitro with interferon-gamma to produce nitric oxide. However, when mouse macrophages were stimulated with haemozoin, a proportional increase of nitric oxide was observed up to 25 μM of haemozoin, followed by a decrease with doses up to 100 μM, when nitric oxide release was completely abrogated. This was not due to reactive oxygen species production, nor to an effect on iNOS activity. Interestingly, when at 24 h, haemozoin-treated macrophages were washed and incubated in fresh medium for further 24 h, the nitric oxide production was restored in a dose–response manner. Similar results were seen when l-arginine-enriched media was used in the stimulation. Moreover, muramyldipeptide, a strong nitric oxide inducer, was unable to activate macrophages to release nitric oxide in the presence of haemozoin-treated medium. By LC–MS/MS a complete depletion of l-arginine was observed in this haemozoin-treated, conditioned medium. Conclusions It is proposed that haemozoin interacts with l-arginine reducing its availability for iNOS, and thus decreasing nitric oxide production. The clinical (or pathological) implications of these results are discussed. Electronic supplementary material The online version of this article (10.1186/s12936-018-2602-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Yolanda Corbett
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, 20133, Milan, MI, Italy. .,Dipartimento di Bioscienze, Università degli Studi di Milano, 20133, Milan, MI, Italy.
| | - Sarah D'Alessandro
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, 20133, Milan, MI, Italy.,Dipartimento di Scienze Biomediche, Chirurgiche e Odontoiatriche, Università degli Studi di Milano, 20133, Milan, MI, Italy
| | - Silvia Parapini
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, 20133, Milan, MI, Italy.,Dipartimento di Scienze Biomediche, Chirurgiche e Odontoiatriche, Università degli Studi di Milano, 20133, Milan, MI, Italy
| | - Diletta Scaccabarozzi
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, 20133, Milan, MI, Italy
| | - Parisa Kalantari
- Department of Immunology, Tufts University School of Medicine, Boston, MA, 02111, USA
| | - Stefania Zava
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, 20133, Milan, MI, Italy
| | - Flavio Giavarini
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, 20133, Milan, MI, Italy
| | - Donatella Caruso
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, 20133, Milan, MI, Italy
| | - Irma Colombo
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, 20133, Milan, MI, Italy
| | - Timothy J Egan
- Department of Chemistry, University of Cape Town, Private Bag X3, Rondebosch, 7701, South Africa
| | - Nicoletta Basilico
- Dipartimento di Scienze Biomediche, Chirurgiche e Odontoiatriche, Università degli Studi di Milano, 20133, Milan, MI, Italy
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15
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Wang Q, Feng Y, Sun X, Pang W, Fu W, Cao Y. Prophylactic treatment of L-Arg improves malaria outcomes by regulating host immune responses during Plasmodium yoelii 17XL infection. Exp Parasitol 2018; 195:1-7. [DOI: 10.1016/j.exppara.2018.09.013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Revised: 02/23/2018] [Accepted: 09/20/2018] [Indexed: 12/24/2022]
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16
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Ong PK, Moreira AS, Daniel-Ribeiro CT, Frangos JA, Carvalho LJM. Reversal of cerebrovascular constriction in experimental cerebral malaria by L-arginine. Sci Rep 2018; 8:15957. [PMID: 30374028 PMCID: PMC6206133 DOI: 10.1038/s41598-018-34249-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Accepted: 10/08/2018] [Indexed: 12/15/2022] Open
Abstract
Vascular dysfunction associated with low nitric oxide (NO) biavailability and low plasma L-arginine levels is observed in both human and experimental cerebral malaria (ECM). In ECM, cerebrovascular constriction results in decreased pial blood flow and hypoxia, and administration of NO donors reverses constriction and increases survival. Supplementation of L-arginine, the substrate for NO synthesis by NO synthases, has been considered as a strategy to improve vascular health and act as adjunctive therapy in human severe malaria. We investigated the effect of L-arginine supplementation on pial vascular tonus of mice with ECM after direct superfusion on the brain surface or systemic delivery. Pial arteriolar diameters of Plasmodium berghei-infected mice with implanted cranial windows were measured using intravital microscopy methods, before and after L-arginine administration. Systemic delivery of L-arginine was performed intravenously, at 10, 50, 100 and 200 mg/kg, as bolus injection or slowly through osmotic pumps, combined or not with artesunate. Direct superfusion of L-arginine (10-7M, 10-5M and 10-3M) on the brain surface of mice with ECM resulted in immediate, consistent and dose-dependent dilation of pial arterioles. ECM mice showed marked cerebrovascular constriction that progressively worsened over a 24 h-period after subcutaneous saline bolus administration. L-arginine administration prevented the worsening in pial constriction at all the doses tested, and at 50 mg/kg and 100 mg/kg it induced temporary reversal of vasoconstriction. Slow, continuous delivery of L-arginine by osmotic pumps, or combined bolus administration of artesunate with L-arginine, also prevented worsening of pial constriction and resulted in improved survival of mice with ECM. L-arginine ameliorates pial vasoconstriction in mice with ECM.
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Affiliation(s)
- Peng Kai Ong
- La Jolla Bioengineering Institute, La Jolla, CA, USA
| | - Aline S Moreira
- Laboratory of Malaria Research, Instituto Oswaldo Cruz, Fiocruz, Rio de Janeiro, Brazil
| | | | | | - Leonardo J M Carvalho
- La Jolla Bioengineering Institute, La Jolla, CA, USA. .,Laboratory of Malaria Research, Instituto Oswaldo Cruz, Fiocruz, Rio de Janeiro, Brazil.
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17
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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: 51] [Impact Index Per Article: 8.5] [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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18
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Shilo NR, Morris CR. Pathways to pulmonary hypertension in sickle cell disease: the search for prevention and early intervention. Expert Rev Hematol 2017; 10:875-890. [PMID: 28817980 DOI: 10.1080/17474086.2017.1364989] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
INTRODUCTION Pulmonary hypertension (PH) develops in a significant number of patients with sickle cell disease (SCD), resulting in increased morbidity and mortality. This review focuses on PH pathophysiology, risk stratification, and new recommendations for screening and treatment for patients with SCD. Areas covered: An extensive PubMed literature search was performed. While the pathophysiology of PH in SCD is yet to be fully deciphered, it is known that the etiology is multifactorial; hemolysis, hypercoagulability, hypoxemia, ischemic-reperfusion injury, oxidative stress, and genetic susceptibility all contribute in varying degrees to endothelial dysfunction. Hemolysis, in particular, seems to play a key role by inciting an imbalance in the regulatory axis of nitric oxide and arginine metabolism. Systematic risk stratification starting in childhood based on clinical features and biomarkers that enable early detection is necessary. Multi-faceted, targeted interventions, before irreversible vasculopathy develops, will allow for improved patient outcomes and life expectancy. Expert commentary: Despite progress in our understanding of PH in SCD, clinically proven therapies remain elusive and additional controlled clinical trials are needed. Prevention of disease starts in childhood, a critical window for intervention. Given the complex and multifactorial nature of SCD, patients will ultimately benefit from combination therapies that simultaneously targets multiple mechanisms.
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Affiliation(s)
- Natalie R Shilo
- a Department of Pediatrics, Division of Pulmonary Medicine , University of Connecticut Heath Center , Farmington , CT , USA
| | - Claudia R Morris
- b Department of Pediatrics, Division of Pediatric Emergency Medicine, Emory-Children's Center for Cystic Fibrosis and Airways Disease Research , Emory University School of Medicine , Atlanta , GA , USA
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19
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Alkaitis MS, Wang H, Ikeda AK, Rowley CA, MacCormick IJC, Chertow JH, Billker O, Suffredini AF, Roberts DJ, Taylor TE, Seydel KB, Ackerman HC. Decreased Rate of Plasma Arginine Appearance in Murine Malaria May Explain Hypoargininemia in Children With Cerebral Malaria. J Infect Dis 2017; 214:1840-1849. [PMID: 27923948 DOI: 10.1093/infdis/jiw452] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2016] [Accepted: 09/16/2016] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Plasmodium infection depletes arginine, the substrate for nitric oxide synthesis, and impairs endothelium-dependent vasodilation. Increased conversion of arginine to ornithine by parasites or host arginase is a proposed mechanism of arginine depletion. METHODS We used high-performance liquid chromatography to measure plasma arginine, ornithine, and citrulline levels in Malawian children with cerebral malaria and in mice infected with Plasmodium berghei ANKA with or without the arginase gene. Heavy isotope-labeled tracers measured by quadrupole time-of-flight liquid chromatography-mass spectrometry were used to quantify the in vivo rate of appearance and interconversion of plasma arginine, ornithine, and citrulline in infected mice. RESULTS Children with cerebral malaria and P. berghei-infected mice demonstrated depletion of plasma arginine, ornithine, and citrulline. Knock out of Plasmodium arginase did not alter arginine depletion in infected mice. Metabolic tracer analysis demonstrated that plasma arginase flux was unchanged by P. berghei infection. Instead, infected mice exhibited decreased rates of plasma arginine, ornithine, and citrulline appearance and decreased conversion of plasma citrulline to arginine. Notably, plasma arginine use by nitric oxide synthase was decreased in infected mice. CONCLUSIONS Simultaneous arginine and ornithine depletion in malaria parasite-infected children cannot be fully explained by plasma arginase activity. Our mouse model studies suggest that plasma arginine depletion is driven primarily by a decreased rate of appearance.
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Affiliation(s)
- Matthew S Alkaitis
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville.,Radcliffe Department of Medicine, University of Oxford, John Radcliffe Hospital, Headington
| | - Honghui Wang
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Bethesda, Maryland
| | - Allison K Ikeda
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville
| | - Carol A Rowley
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville
| | - Ian J C MacCormick
- Department of Eye and Vision Science, University of Liverpool.,Centre for Clinical Brain Sciences, University of Edinburgh.,Malawi-Liverpool-Wellcome Trust Clinical Research Programme
| | - Jessica H Chertow
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville
| | | | - Anthony F Suffredini
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Bethesda, Maryland
| | - David J Roberts
- Radcliffe Department of Medicine, University of Oxford, John Radcliffe Hospital, Headington.,National Health Service Blood and Transplant, John Radcliffe Hospital, Oxford, United Kingdom
| | - Terrie E Taylor
- Michigan State University, East Lansing.,Blantyre Malaria Project, Malawi
| | - Karl B Seydel
- Michigan State University, East Lansing.,Blantyre Malaria Project, Malawi
| | - Hans C Ackerman
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville
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20
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Morris CR, Hamilton-Reeves J, Martindale RG, Sarav M, Ochoa Gautier JB. Acquired Amino Acid Deficiencies: A Focus on Arginine and Glutamine. Nutr Clin Pract 2017; 32:30S-47S. [PMID: 28388380 DOI: 10.1177/0884533617691250] [Citation(s) in RCA: 92] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Nonessential amino acids are synthesized de novo and therefore not diet dependent. In contrast, essential amino acids must be obtained through nutrition since they cannot be synthesized internally. Several nonessential amino acids may become essential under conditions of stress and catabolic states when the capacity of endogenous amino acid synthesis is exceeded. Arginine and glutamine are 2 such conditionally essential amino acids and are the focus of this review. Low arginine bioavailability plays a pivotal role in the pathogenesis of a growing number of varied diseases, including sickle cell disease, thalassemia, malaria, acute asthma, cystic fibrosis, pulmonary hypertension, cardiovascular disease, certain cancers, and trauma, among others. Catabolism of arginine by arginase enzymes is the most common cause of an acquired arginine deficiency syndrome, frequently contributing to endothelial dysfunction and/or T-cell dysfunction, depending on the clinical scenario and disease state. Glutamine, an arginine precursor, is one of the most abundant amino acids in the body and, like arginine, becomes deficient in several conditions of stress, including critical illness, trauma, infection, cancer, and gastrointestinal disorders. At-risk populations are discussed together with therapeutic options that target these specific acquired amino acid deficiencies.
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Affiliation(s)
- Claudia R Morris
- 1 Department of Pediatrics, Division of Pediatric Emergency Medicine, Emory-Children's Center for Cystic Fibrosis and Airways Disease Research, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Jill Hamilton-Reeves
- 2 Department of Dietetics and Nutrition, University of Kansas, Kansas City, Kansas, USA
| | - Robert G Martindale
- 3 Department of Surgery, Oregon Health and Science University, Portland, Oregon, USA
| | - Menaka Sarav
- 4 Department of Medicine, Division of Nephrology, Northshore University Health System, University of Chicago, Chicago, Illinois, USA
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21
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Jeeyapant A, Kingston HW, Plewes K, Maude RJ, Hanson J, Herdman MT, Leopold SJ, Ngernseng T, Charunwatthana P, Phu NH, Ghose A, Hasan MMU, Fanello CI, Faiz MA, Hien TT, Day NPJ, White NJ, Dondorp AM. Defining Surrogate Endpoints for Clinical Trials in Severe Falciparum Malaria. PLoS One 2017; 12:e0169307. [PMID: 28052109 PMCID: PMC5215574 DOI: 10.1371/journal.pone.0169307] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2016] [Accepted: 12/14/2016] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Clinical trials in severe falciparum malaria require a large sample size to detect clinically meaningful differences in mortality. This means few interventions can be evaluated at any time. Using a validated surrogate endpoint for mortality would provide a useful alternative allowing a smaller sample size. Here we evaluate changes in coma score and plasma lactate as surrogate endpoints for mortality in severe falciparum malaria. METHODS Three datasets of clinical studies in severe malaria were re-evaluated: studies from Chittagong, Bangladesh (adults), the African 'AQUAMAT' trial comparing artesunate and quinine (children), and the Vietnamese 'AQ' study (adults) comparing artemether with quinine. The absolute change, relative change, slope of the normalization over time, and time to normalization were derived from sequential measurements of plasma lactate and coma score, and validated for their use as surrogate endpoint, including the proportion of treatment effect on mortality explained (PTE) by these surrogate measures. RESULTS Improvements in lactate concentration or coma scores over the first 24 hours of admission, were strongly prognostic for survival in all datasets. In hyperlactataemic patients in the AQ study (n = 173), lower mortality with artemether compared to quinine closely correlated with faster reduction in plasma lactate concentration, with a high PTE of the relative change in plasma lactate at 8 and 12 hours of 0.81 and 0.75, respectively. In paediatric patients enrolled in the 'AQUAMAT' study with cerebral malaria (n = 785), mortality was lower with artesunate compared to quinine, but this was not associated with faster coma recovery. CONCLUSIONS The relative changes in plasma lactate concentration assessed at 8 or 12 hours after admission are valid surrogate endpoints for severe malaria studies on antimalarial drugs or adjuvant treatments aiming at improving the microcirculation. Measures of coma recovery are not valid surrogate endpoints for mortality.
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Affiliation(s)
- Atthanee Jeeyapant
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Hugh W. Kingston
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Charles Darwin University, Darwin, Northern Territory, Australia
- Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, United Kingdom
| | - Katherine Plewes
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, United Kingdom
| | - Richard J. Maude
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Josh Hanson
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Global Health Division, Menzies School of Health Research, Darwin, Australia
| | - M. Trent Herdman
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- University College, Oxford, United Kingdom
| | - Stije J. Leopold
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Thatsanun Ngernseng
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Prakaykaew Charunwatthana
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Department of Clinical Tropical Medicine, Faculty of Tropical Medicine, Mahidol Unversity,Bangkok,Thailand
| | - Nguyen Hoan Phu
- Oxford University Clinical Research Unit. Hospital for Tropical Diseases, Ho Chi Minh City, Vietnam
| | - Aniruddha Ghose
- Department of Medicine, Chittagong Medical College Hospital, Chittagong, Bangladesh
| | | | - Caterina I. Fanello
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Kinshasa School of Public Health, University of Kinshasa, Kinshasa, Democratic Republic of the Congo
| | - Md Abul Faiz
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Malaria Research Group, Dev Care Foundation, Dhaka, Bangladesh
| | - Tran Tinh Hien
- Oxford University Clinical Research Unit. Hospital for Tropical Diseases, Ho Chi Minh City, Vietnam
| | - Nicholas P. J. Day
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, United Kingdom
| | - Nicholas J. White
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, United Kingdom
| | - Arjen M. Dondorp
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, United Kingdom
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22
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Alkaitis MS, Ackerman HC. Tetrahydrobiopterin Supplementation Improves Phenylalanine Metabolism in a Murine Model of Severe Malaria. ACS Infect Dis 2016; 2:827-838. [PMID: 27641435 PMCID: PMC6289270 DOI: 10.1021/acsinfecdis.6b00124] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Tetrahydrobiopterin (BH4) is an essential cofactor for both phenylalanine hydroxylase and nitric oxide synthase. Patients with severe malaria have low urinary BH4, elevated plasma phenylalanine, and impaired endothelium-dependent vasodilation, suggesting that BH4 depletion may limit phenylalanine metabolism and nitric oxide synthesis. We infected C57BL/6 mice with Plasmodium berghei ANKA to characterize BH4 availability and to investigate the effects of BH4 supplementation. P. berghei ANKA infection lowered BH4 in plasma, erythrocytes, and brain tissue but raised it in aorta and liver tissue. The ratio of BH4 to 7,8-BH2 (the major product of BH4 oxidation) was decreased in plasma, erythrocytes, and brain tissue, suggesting that oxidation contributes to BH4 depletion. The continuous infusion of sepiapterin (a BH4 precursor) and citrulline (an arginine precursor) raised the concentrations of BH4 and arginine in both blood and tissue compartments. The restoration of systemic BH4 and arginine availability in infected mice produced only a minor improvement in whole blood nitrite concentrations, a biomarker of NO synthesis, and failed to prevent the onset of severe disease symptoms. However, sepiapterin and citrulline infusion reduced the ratio of phenylalanine to tyrosine in plasma, aortic tissue, and brain tissue. In summary, BH4 depletion in P. berghei infection may compromise both nitric oxide synthesis and phenylalanine metabolism; however, these findings require further investigation in human patients with severe malaria.
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Affiliation(s)
- Matthew S. Alkaitis
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892, United States
- Radcliffe Department of Medicine, University of Oxford, John Radcliffe Hospital, Headington Oxford, United Kingdom
| | - Hans C. Ackerman
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892, United States
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23
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Severe malaria: what's new on the pathogenesis front? Int J Parasitol 2016; 47:145-152. [PMID: 27670365 DOI: 10.1016/j.ijpara.2016.08.002] [Citation(s) in RCA: 71] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Revised: 08/09/2016] [Accepted: 08/15/2016] [Indexed: 12/25/2022]
Abstract
Plasmodium falciparum causes the most severe and fatal form of malaria in humans with over half a million deaths each year. Cerebral malaria, a complex neurological syndrome of severe falciparum malaria, is often fatal and represents a major public health burden. Despite vigorous efforts, the pathophysiology of cerebral malaria remains to be elucidated, thereby hindering the development of adjunctive therapies. In recent years, multidisciplinary and collaborative approaches have led to groundbreaking progress both in the laboratory and in the field. Here we review the latest breakthroughs in severe malaria pathogenesis, with a specific focus on new pathogenetic mechanisms leading to cerebral malaria. The most recent findings point towards specific parasite phenotypes targeting brain microvasculature, endothelial dysfunction and subsequent oedema-induced brain swelling.
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Kayano ACAV, Dos-Santos JCK, Bastos MF, Carvalho LJ, Aliberti J, Costa FTM. Pathophysiological Mechanisms in Gaseous Therapies for Severe Malaria. Infect Immun 2016; 84:874-882. [PMID: 26831465 PMCID: PMC4807480 DOI: 10.1128/iai.01404-15] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Over 200 million people worldwide suffer from malaria every year, a disease that causes 584,000 deaths annually. In recent years, significant improvements have been achieved on the treatment of severe malaria, with intravenous artesunate proving superior to quinine. However, mortality remains high, at 8% in children and 15% in adults in clinical trials, and even worse in the case of cerebral malaria (18% and 30%, respectively). Moreover, some individuals who do not succumb to severe malaria present long-term cognitive deficits. These observations indicate that strategies focused only on parasite killing fail to prevent neurological complications and deaths associated with severe malaria, possibly because clinical complications are associated in part with a cerebrovascular dysfunction. Consequently, different adjunctive therapies aimed at modulating malaria pathophysiological processes are currently being tested. However, none of these therapies has shown unequivocal evidence in improving patient clinical status. Recently, key studies have shown that gaseous therapies based mainly on nitric oxide (NO), carbon monoxide (CO), and hyperbaric (pressurized) oxygen (HBO) alter vascular endothelium dysfunction and modulate the host immune response to infection. Considering gaseous administration as a promising adjunctive treatment against severe malaria cases, we review here the pathophysiological mechanisms and the immunological aspects of such therapies.
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Affiliation(s)
- Ana Carolina A V Kayano
- Laboratory of Tropical Diseases-Prof. Dr. Luiz Jacintho da Silva, Department of Genetics, Evolution and Bioagents, Institute of Biology, University of Campinas, Campinas, SP, Brazil
| | - João Conrado K Dos-Santos
- Laboratory of Tropical Diseases-Prof. Dr. Luiz Jacintho da Silva, Department of Genetics, Evolution and Bioagents, Institute of Biology, University of Campinas, Campinas, SP, Brazil
| | - Marcele F Bastos
- Laboratory of Tropical Diseases-Prof. Dr. Luiz Jacintho da Silva, Department of Genetics, Evolution and Bioagents, Institute of Biology, University of Campinas, Campinas, SP, Brazil
| | - Leonardo J Carvalho
- Laboratory of Malaria Research, Instituto Oswaldo Cruz, FIOCRUZ, Rio de Janeiro, RJ, Brazil
| | - Júlio Aliberti
- Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA
| | - Fabio T M Costa
- Laboratory of Tropical Diseases-Prof. Dr. Luiz Jacintho da Silva, Department of Genetics, Evolution and Bioagents, Institute of Biology, University of Campinas, Campinas, SP, Brazil
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25
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Panackal AA, Williamson KC, van de Beek D, Boulware DR, Williamson PR. Fighting the Monster: Applying the Host Damage Framework to Human Central Nervous System Infections. mBio 2016; 7:e01906-15. [PMID: 26814182 PMCID: PMC4742705 DOI: 10.1128/mbio.01906-15] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The host damage-response framework states that microbial pathogenesis is a product of microbial virulence factors and collateral damage from host immune responses. Immune-mediated host damage is particularly important within the size-restricted central nervous system (CNS), where immune responses may exacerbate cerebral edema and neurological damage, leading to coma and death. In this review, we compare human host and therapeutic responses in representative nonviral generalized CNS infections that induce archetypal host damage responses: cryptococcal menigoencephalitis and tuberculous meningitis in HIV-infected and non-HIV-infected patients, pneumococcal meningitis, and cerebral malaria. Consideration of the underlying patterns of host responses provides critical insights into host damage and may suggest tailored adjunctive therapeutics to improve disease outcome.
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Affiliation(s)
- Anil A Panackal
- Laboratory of Clinical Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Kim C Williamson
- Department of Microbiology and Immunology, Uniformed Services University of the Health Sciences, Bethesda, Maryland, USA
| | - Diederik van de Beek
- Department of Neurology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - David R Boulware
- Division of Infectious Diseases and International Medicine, Department of Medicine, University of Minnesota, Minneapolis, Minnesota, USA
| | - Peter R Williamson
- Laboratory of Clinical Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
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Pharmacokinetic-Pharmacodynamic Model for the Effect of l-Arginine on Endothelial Function in Patients with Moderately Severe Falciparum Malaria. Antimicrob Agents Chemother 2015; 60:198-205. [PMID: 26482311 DOI: 10.1128/aac.01479-15] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Accepted: 10/13/2015] [Indexed: 11/20/2022] Open
Abstract
Impaired organ perfusion in severe falciparum malaria arises from microvascular sequestration of parasitized cells and endothelial dysfunction. Endothelial dysfunction in malaria is secondary to impaired nitric oxide (NO) bioavailability, in part due to decreased plasma concentrations of l-arginine, the substrate for endothelial cell NO synthase. We quantified the time course of the effects of adjunctive l-arginine treatment on endothelial function in 73 patients with moderately severe falciparum malaria derived from previous studies. Three groups of 10 different patients received 3 g, 6 g, or 12 g of l-arginine as a half-hour infusion. The remaining 43 received saline placebo. A pharmacokinetic-pharmacodynamic (PKPD) model was developed to describe the time course of changes in exhaled NO concentrations and reactive hyperemia-peripheral arterial tonometry (RH-PAT) index values describing endothelial function and then used to explore optimal dosing regimens for l-arginine. A PK model describing arginine concentrations in patients with moderately severe malaria was extended with two pharmacodynamic biomeasures, the intermediary biochemical step (NO production) and endothelial function (RH-PAT index). A linear model described the relationship between arginine concentrations and exhaled NO. NO concentrations were linearly related to RH-PAT index. Simulations of dosing schedules using this PKPD model predicted that the time within therapeutic range would increase with increasing arginine dose. However, simulations demonstrated that regimens of continuous infusion over longer periods would prolong the time within the therapeutic range even more. The optimal dosing regimen for l-arginine is likely to be administration schedule dependent. Further studies are necessary to characterize the effects of such continuous infusions of l-arginine on NO and microvascular reactivity in severe malaria.
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27
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Eisenhut M. The evidence for a role of vasospasm in the pathogenesis of cerebral malaria. Malar J 2015; 14:405. [PMID: 26463364 PMCID: PMC4603731 DOI: 10.1186/s12936-015-0928-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2015] [Accepted: 10/01/2015] [Indexed: 12/31/2022] Open
Abstract
Due to delay in treatment, cerebral malaria (CM) remains a significant complication of Plasmodium falciparum infection and is a common cause of death from malaria. In addition, more than 10 % of children surviving CM have neurological and long-term cognitive deficits. Understanding the pathogenesis of CM enables design of supportive treatment, reducing neurological morbidity and mortality. Vaso-occlusion and brain swelling appear to be leading to clinical features, neuronal damage and death in CM. It is proposed that parasitized red blood cells (pRBC), due to cytoadhesion to the endothelium and vasospasm induced by reduced bioavailability of nitric oxide, are causes. Stasis of blood flow and accumulation of pRBC may allow, after schizont rupture, for high concentration of products of haemolysis to accumulate, which leads to localized nitric oxide depletion, inducing adhesion molecules and cerebral vasospasm. Features consistent with an involvement of vasospasm are rapid reversibility of neurological symptoms, intermittently increased or absent flow in medium cerebral artery detectable on Doppler ultrasound and hemispheric reversible changes on cerebral magnetic resonance imaging in some patients. Clinical trials of treatment that can rapidly reduce cerebral vasospasm, including nitric oxide donors, inhaled nitric oxide, endothelin or calcium antagonists, or tissue plasminogen activators, are warranted.
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Affiliation(s)
- Michael Eisenhut
- Luton and Dunstable University Hospital NHS Foundation Trust, Lewsey Road, Luton, LU4ODZ, UK.
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28
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Abidin RS, Lua LHL, Middelberg APJ, Sainsbury F. Insert engineering and solubility screening improves recovery of virus-like particle subunits displaying hydrophobic epitopes. Protein Sci 2015; 24:1820-8. [PMID: 26401641 DOI: 10.1002/pro.2775] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Accepted: 08/20/2015] [Indexed: 11/09/2022]
Abstract
The Polyomavirus coat protein, VP1 has been developed as an epitope presentation system able to provoke humoral immunity against a variety of pathogens, such as Influenza and Group A Streptococcus. The ability of the system to carry cytotoxic T cell epitopes on a surface-exposed loop and the impact on protein solubility has not been examined. Four variations of three selected epitopes were cloned into surface-exposed loops of VP1, and expressed in Escherichia coli. VP1 pentamers, also known as capsomeres, were purified via a glutathione-S-transferase tag. Size exclusion chromatography indicated severe aggregation of the recombinant VP1 during enzymatic tag removal resulting from the introduction the hydrophobic epitopes. Inserts were modified to possess double aspartic acid residues at each end of the hydrophobic epitopes and a high-throughput buffer condition screen was implemented with protein aggregation monitored during tag removal by spectrophotometry and dynamic light scattering. These analyses showed that the insertion of charged residues at the extremities of epitopes could improve solubility of capsomeres and revealed multiple windows of opportunity for further condition optimization. A combination of epitope design, pH optimization, and the additive l-arginine permitted the recovery of soluble VP1 pentamers presenting hydrophobic epitopes and their subsequent assembly into virus-like particles.
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Affiliation(s)
- R S Abidin
- The University of Queensland, Australian Institute for Bioengineering and Nanotechnology Centre for Biomolecular Engineering, St Lucia, Queensland, 4072, Australia
| | - L H L Lua
- Protein Expression Facility, The University of Queensland, St Lucia, Queensland, 4072, Australia
| | - A P J Middelberg
- The University of Queensland, Australian Institute for Bioengineering and Nanotechnology Centre for Biomolecular Engineering, St Lucia, Queensland, 4072, Australia
| | - F Sainsbury
- The University of Queensland, Australian Institute for Bioengineering and Nanotechnology Centre for Biomolecular Engineering, St Lucia, Queensland, 4072, Australia
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29
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Endothelial-Leukocyte Interaction in Severe Malaria: Beyond the Brain. Mediators Inflamm 2015; 2015:168937. [PMID: 26491221 PMCID: PMC4605361 DOI: 10.1155/2015/168937] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2015] [Revised: 08/25/2015] [Accepted: 09/01/2015] [Indexed: 01/23/2023] Open
Abstract
Malaria is the most important parasitic disease worldwide, accounting for 1 million deaths each year. Severe malaria is a systemic illness characterized by dysfunction of brain tissue and of one or more peripheral organs as lungs and kidney. The most severe and most studied form of malaria is associated with cerebral complications due to capillary congestion and the adhesion of infected erythrocytes, platelets, and leukocytes to brain vasculature. Thus, leukocyte rolling and adhesion in the brain vascular bed during severe malaria is singular and distinct from other models of inflammation. The leukocyte/endothelium interaction and neutrophil accumulation are also observed in the lungs. However, lung interactions differ from brain interactions, likely due to differences in the blood-brain barrier and blood-air barrier tight junction composition of the brain and lung endothelium. Here, we review the importance of endothelial dysfunction and the mechanism of leukocyte/endothelium interaction during severe malaria. Furthermore, we hypothesize a possible use of adjunctive therapies to antimalarial drugs that target the interaction between the leukocytes and the endothelium.
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30
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Carvalho LJDM, Moreira ADS, Daniel-Ribeiro CT, Martins YC. Vascular dysfunction as a target for adjuvant therapy in cerebral malaria. Mem Inst Oswaldo Cruz 2015; 109:577-88. [PMID: 25185000 PMCID: PMC4156451 DOI: 10.1590/0074-0276140061] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2014] [Accepted: 04/02/2014] [Indexed: 12/27/2022] Open
Abstract
Cerebral malaria (CM) is a life-threatening complication of Plasmodium
falciparum malaria that continues to be a major global health problem.
Brain vascular dysfunction is a main factor underlying the pathogenesis of CM and can
be a target for the development of adjuvant therapies for the disease. Vascular
occlusion by parasitised red blood cells and vasoconstriction/vascular dysfunction
results in impaired cerebral blood flow, ischaemia, hypoxia, acidosis and death. In
this review, we discuss the mechanisms of vascular dysfunction in CM and the roles of
low nitric oxide bioavailability, high levels of endothelin-1 and dysfunction of the
angiopoietin-Tie2 axis. We also discuss the usefulness and relevance of the murine
experimental model of CM by Plasmodium berghei ANKA to identify
mechanisms of disease and to screen potential therapeutic interventions.
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Affiliation(s)
| | - Aline da Silva Moreira
- Laboratório de Pesquisas em Malária, Instituto Oswaldo Cruz-Fiocruz, Rio de Janeiro, RJ, Brasil
| | | | - Yuri Chaves Martins
- Department of Pathology, Albert Einstein College of Medicine, Bronx, NY, USA
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31
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Abstract
Over 90% of the world's severe and fatal Plasmodium falciparum malaria is estimated to affect young children in sub-Sahara Africa, where it remains a common cause of hospital admission and inpatient mortality. Few children will ever be managed on high dependency or intensive care units and, therefore, rely on simple supportive treatments and parenteral anti-malarials. There has been some progress on defining best practice for antimalarial treatment with the publication of the AQUAMAT trial in 2010, involving 5,425 children at 11 centres across 9 African countries, showing that in artesunate-treated children, the relative risk of death was 22.5% (95% confidence interval (CI) 8.1 to 36.9) lower than in those receiving quinine. Human trials of supportive therapies carried out on the basis of pathophysiology studies, have so far made little progress on reducing mortality; despite appearing to reduce morbidity endpoints, more often than not they have led to an excess of adverse outcomes. This review highlights the spectrum of complications in African children with severe malaria, the therapeutic challenges of managing these in resource-poor settings and examines in-depth the results from clinical trials with a view to identifying the treatment priorities and a future research agenda.
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32
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Yeo TW, Lampah DA, Kenangalem E, Tjitra E, Price RN, Weinberg JB, Hyland K, Granger DL, Anstey NM. Impaired systemic tetrahydrobiopterin bioavailability and increased dihydrobiopterin in adult falciparum malaria: association with disease severity, impaired microvascular function and increased endothelial activation. PLoS Pathog 2015; 11:e1004667. [PMID: 25764397 PMCID: PMC4357386 DOI: 10.1371/journal.ppat.1004667] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Accepted: 01/07/2015] [Indexed: 12/22/2022] Open
Abstract
Tetrahydrobiopterin (BH₄) is a co-factor required for catalytic activity of nitric oxide synthase (NOS) and amino acid-monooxygenases, including phenylalanine hydroxylase. BH4 is unstable: during oxidative stress it is non-enzymatically oxidized to dihydrobiopterin (BH₂), which inhibits NOS. Depending on BH₄ availability, NOS oscillates between NO synthase and NADPH oxidase: as the BH₄/BH₂ ratio decreases, NO production falls and is replaced by superoxide. In African children and Asian adults with severe malaria, NO bioavailability decreases and plasma phenylalanine increases, together suggesting possible BH₄ deficiency. The primary three biopterin metabolites (BH₄, BH₂ and B₀ [biopterin]) and their association with disease severity have not been assessed in falciparum malaria. We measured pterin metabolites in urine of adults with severe falciparum malaria (SM; n=12), moderately-severe malaria (MSM, n=17), severe sepsis (SS; n=5) and healthy subjects (HC; n=20) as controls. In SM, urinary BH₄ was decreased (median 0.16 ¼mol/mmol creatinine) compared to MSM (median 0.27), SS (median 0.54), and HC (median 0.34)]; p<0.001. Conversely, BH₂ was increased in SM (median 0.91 ¼mol/mmol creatinine), compared to MSM (median 0.67), SS (median 0.39), and HC (median 0.52); p<0.001, suggesting increased oxidative stress and insufficient recycling of BH2 back to BH4 in severe malaria. Overall, the median BH₄/BH₂ ratio was lowest in SM [0.18 (IQR: 0.04-0.32)] compared to MSM (0.45, IQR 0.27-61), SS (1.03; IQR 0.54-2.38) and controls (0.66; IQR 0.43-1.07); p<0.001. In malaria, a lower BH₄/BH₂ ratio correlated with decreased microvascular reactivity (r=0.41; p=0.03) and increased ICAM-1 (r=-0.52; p=0.005). Decreased BH4 and increased BH₂ in severe malaria (but not in severe sepsis) uncouples NOS, leading to impaired NO bioavailability and potentially increased oxidative stress. Adjunctive therapy to regenerate BH4 may have a role in improving NO bioavailability and microvascular perfusion in severe falciparum malaria.
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Affiliation(s)
- Tsin W. Yeo
- Global and Tropical Health Division, Menzies School of Health Research and Charles Darwin University, Darwin, Northern Territory, Australia
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore
- Institute of Infectious Disease and Epidemiology, Tan Tock Seng Hospital, Singapore
| | - Daniel A. Lampah
- Menzies School of Health Research-National Institute of Health Research and Development Research Program, and District Ministry of Health, Timika, Papua, Indonesia
| | - Enny Kenangalem
- Menzies School of Health Research-National Institute of Health Research and Development Research Program, and District Ministry of Health, Timika, Papua, Indonesia
| | - Emiliana Tjitra
- National Institute of Health Research and Development, Jakarta, Indonesia
| | - Ric N. Price
- Global and Tropical Health Division, Menzies School of Health Research and Charles Darwin University, Darwin, Northern Territory, Australia
- Centre for Tropical Medicine, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, United Kingdom
| | - J. Brice Weinberg
- Duke University and VA Medical Centers, Durham, North Carolina, United States of America
| | - Keith Hyland
- Medical Neurogenetics LLC, Atlanta, Georgia, United States of America
| | - Donald L. Granger
- Division of Infectious Diseases, University of Utah and Veterans Affairs Medical Center, Salt Lake City, Utah, United States of America
| | - Nicholas M. Anstey
- Global and Tropical Health Division, Menzies School of Health Research and Charles Darwin University, Darwin, Northern Territory, Australia
- Division of Medicine, Royal Darwin Hospital, Darwin, Northern Territory, Australia
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33
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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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34
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Control of Disease Tolerance to Malaria by Nitric Oxide and Carbon Monoxide. Cell Rep 2014; 8:126-36. [DOI: 10.1016/j.celrep.2014.05.054] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2014] [Revised: 04/23/2014] [Accepted: 05/29/2014] [Indexed: 12/30/2022] Open
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35
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Yeo TW, Lampah DA, Kenangalem E, Tjitra E, Weinberg JB, Granger DL, Price RN, Anstey NM. Decreased endothelial nitric oxide bioavailability, impaired microvascular function, and increased tissue oxygen consumption in children with falciparum malaria. J Infect Dis 2014; 210:1627-32. [PMID: 24879801 DOI: 10.1093/infdis/jiu308] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Endothelial nitric oxide (NO) bioavailability, microvascular function, and host oxygen consumption have not been assessed in pediatric malaria. We measured NO-dependent endothelial function by using peripheral artery tonometry to determine the reactive hyperemia index (RHI), and microvascular function and oxygen consumption (VO2) using near infrared resonance spectroscopy in 13 Indonesian children with severe falciparum malaria and 15 with moderately severe falciparum malaria. Compared with 19 controls, children with severe malaria and those with moderately severe malaria had lower RHIs (P = .03); 12% and 8% lower microvascular function, respectively (P = .03); and 29% and 25% higher VO2, respectively. RHIs correlated with microvascular function in all children with malaria (P < .001) and all with severe malaria (P < .001). Children with malaria have decreased endothelial and microvascular function and increased oxygen consumption, likely contributing to the pathogenesis of the disease.
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Affiliation(s)
- Tsin W Yeo
- Global Health Division, Menzies School of Health Research and Charles Darwin University Lee Kong Chian School of Medicine, Nanyang Technological University Institute of Infectious Disease and Epidemiology, Tan Tock Seng Hospital, Singapore
| | - Daniel A Lampah
- District Ministry of Health, Menzies School of Health Research-National Institute of Health Research and Development Research Program, Timika
| | - Enny Kenangalem
- District Ministry of Health, Menzies School of Health Research-National Institute of Health Research and Development Research Program, Timika
| | - Emiliana Tjitra
- National Institute of Health Research and Development, Jakarta, Indonesia
| | - J Brice Weinberg
- Division of Hematology, Department of Medicine, School of Medicine, Duke University Division of Hematology-Oncology, Durham VA Medical Center, North Carolina
| | - Donald L Granger
- Division of Infectious Diseases, Department of Internal Medicine, University of Utah School of Medicine, Division of Infectious Diseases, Department of Internal Medicine, VA Salt Lake Health Care System, Salt Lake City, Utah
| | - Ric N Price
- Global Health Division, Menzies School of Health Research and Charles Darwin University Division of Medicine, Royal Darwin Hospital, Australia Centre for Vaccinology and Tropical Medicine, Nuffield Department of Clinical Medicine, Churchill Hospital, Oxford, United Kingdom
| | - Nicholas M Anstey
- Global Health Division, Menzies School of Health Research and Charles Darwin University Division of Medicine, Royal Darwin Hospital, Australia
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36
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Polimeni M, Prato M. Host matrix metalloproteinases in cerebral malaria: new kids on the block against blood-brain barrier integrity? Fluids Barriers CNS 2014; 11:1. [PMID: 24467887 PMCID: PMC3905658 DOI: 10.1186/2045-8118-11-1] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2013] [Accepted: 01/24/2014] [Indexed: 12/23/2022] Open
Abstract
Cerebral malaria (CM) is a life-threatening complication of falciparum malaria, associated with high mortality rates, as well as neurological impairment in surviving patients. Despite disease severity, the etiology of CM remains elusive. Interestingly, although the Plasmodium parasite is sequestered in cerebral microvessels, it does not enter the brain parenchyma: so how does Plasmodium induce neuronal dysfunction? Several independent research groups have suggested a mechanism in which increased blood–brain barrier (BBB) permeability might allow toxic molecules from the parasite or the host to enter the brain. However, the reported severity of BBB damage in CM is variable depending on the model system, ranging from mild impairment to full BBB breakdown. Moreover, the factors responsible for increased BBB permeability are still unknown. Here we review the prevailing theories on CM pathophysiology and discuss new evidence from animal and human CM models implicating BBB damage. Finally, we will review the newly-described role of matrix metalloproteinases (MMPs) and BBB integrity. MMPs comprise a family of proteolytic enzymes involved in modulating inflammatory response, disrupting tight junctions, and degrading sub-endothelial basal lamina. As such, MMPs represent potential innovative drug targets for CM.
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Affiliation(s)
| | - Mauro Prato
- Dipartimento di Neuroscienze, Università di Torino, C,so Raffaello 30, 10125 Torino, Italy.
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