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Bush MA, Anstey NM, Yeo TW, Florence SM, Granger DL, Mwaikambo ED, Weinberg JB. Vascular Dysfunction in Malaria: Understanding the Role of the Endothelial Glycocalyx. Front Cell Dev Biol 2021; 9:751251. [PMID: 34858979 PMCID: PMC8631294 DOI: 10.3389/fcell.2021.751251] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Accepted: 09/27/2021] [Indexed: 01/18/2023] Open
Abstract
Malaria caused by Plasmodium falciparum results in over 400,000 deaths annually, predominantly affecting African children. In addition, non-falciparum species including vivax and knowlesi cause significant morbidity and mortality. Vascular dysfunction is a key feature in malaria pathogenesis leading to impaired blood perfusion, vascular obstruction, and tissue hypoxia. Contributing factors include adhesion of infected RBC to endothelium, endothelial activation, and reduced nitric oxide formation. Endothelial glycocalyx (eGC) protects the vasculature by maintaining vessel integrity and regulating cellular adhesion and nitric oxide signaling pathways. Breakdown of eGC is known to occur in infectious diseases such as bacterial sepsis and dengue and is associated with adverse outcomes. Emerging studies using biochemical markers and in vivo imaging suggest that eGC breakdown occurs during Plasmodium infection and is associated with markers of malaria disease severity, endothelial activation, and vascular function. In this review, we describe characteristics of eGC breakdown in malaria and discuss how these relate to vascular dysfunction and adverse outcomes. Further understanding of this process may lead to adjunctive therapy to preserve or restore damaged eGC and reduce microvascular dysfunction and the morbidity/mortality of malaria.
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Affiliation(s)
- Margaret A Bush
- Duke University School of Nursing and Durham VA Medical Centers, Durham, NC, United States
| | - Nicholas M Anstey
- Menzies School of Health Research, Charles Darwin University, Darwin, NT, Australia
| | - Tsin W Yeo
- Menzies School of Health Research, Charles Darwin University, Darwin, NT, Australia.,Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore.,National Centre for Infectious Diseases, Tan Tock Seng Hospital, Singapore, Singapore
| | | | - Donald L Granger
- School of Medicine, University of Utah and Salt Lake City VA Medical Centers, Salt Lake City, UT, United States
| | | | - J Brice Weinberg
- Duke University School of Medicine and Durham VA Medical Centers, Durham, NC, United States
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Bush MA, Florence SM, Yeo TW, Kalingonji AR, Chen Y, Granger DL, Rubach MP, Anstey NM, Mwaikambo ED, Weinberg JB. Degradation of endothelial glycocalyx in Tanzanian children with falciparum malaria. FASEB J 2021; 35:e21805. [PMID: 34403544 DOI: 10.1096/fj.202100277rr] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2021] [Revised: 06/25/2021] [Accepted: 07/01/2021] [Indexed: 01/20/2023]
Abstract
A layer of glycocalyx covers the vascular endothelium serving important protective and homeostatic functions. The objective of this study was to determine if breakdown of the endothelial glycocalyx (eGC) occurs during malaria infection in children. Measures of eGC integrity, endothelial activation, and microvascular reactivity were prospectively evaluated in 146 children: 44 with moderately severe malaria (MSM), 42 with severe malaria (SM), and 60 healthy controls (HC). Biochemical measures of eGC integrity included plasma syndecan-1 and total urinary glycosaminoglycans (GAG). Side-stream dark field imaging was used to quantitatively assess integrity of eGC. Plasma angiopoietin-2 (Ang-2) was measured as a marker of endothelial activation and also as a possible mediator of eGC breakdown. Our results show that urinary GAG, syndecan-1, and Ang-2 were elevated in patients with MSM and SM compared with HC. Syndecan-1 and GAG levels correlated significantly with each other and with plasma Ang-2. The eGC breakdown products also inversely correlated significantly with hemoglobin and platelet count. In the MSM group, imaging results provided further evidence for eGC degradation. Although not correlated with markers of eGC degradation, vascular function (assessed by non-invasive near infrared spectroscopy [NIRS]) demonstrated reduced microvascular reactivity, particularly affecting the SM group. Our findings provide further evidence for breakdown of eGC in falciparum malaria that may contribute to endothelial activation and adhesion of parasitized red blood cells, with reduced nitric oxide formation, and vascular dysfunction.
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Affiliation(s)
- Margaret A Bush
- School of Medicine, Duke University and Durham VA Medical Centers, Durham, NC, USA
| | | | - Tsin W Yeo
- Menzies School of Health Research, Charles Darwin University, Darwin, Australia.,Lee Kong Chian School of Medicine, Nanyang Technological University, Republic of Singapore.,National Centre for Infectious Diseases, Tan Tock Seng Hospital, Republic of Singapore
| | | | - Youwei Chen
- School of Medicine, Duke University and Durham VA Medical Centers, Durham, NC, USA
| | - Donald L Granger
- University of Utah and VA Medical Centers, Salt Lake City, UT, USA
| | - Matthew P Rubach
- School of Medicine, Duke University and Durham VA Medical Centers, Durham, NC, USA
| | - Nicholas M Anstey
- Menzies School of Health Research, Charles Darwin University, Darwin, Australia
| | | | - Joe Brice Weinberg
- School of Medicine, Duke University and Durham VA Medical Centers, Durham, NC, USA
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Yeo TW, Bush PA, Chen Y, Young SP, Zhang H, Millington DS, Granger DL, Mwaikambo ED, Anstey NM, Weinberg JB. Glycocalyx breakdown is increased in African children with cerebral and uncomplicated falciparum malaria. FASEB J 2019; 33:14185-14193. [PMID: 31658834 DOI: 10.1096/fj.201901048rr] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Cerebral malaria (CM) from Plasmodium falciparum infection is associated with endothelial dysfunction and parasite sequestration. The glycocalyx (GCX), a carbohydrate-rich layer lining the endothelium, is crucial in vascular homeostasis. To evaluate the role of its loss in the pathogenesis of pediatric CM, we measured GCX degradation in Tanzanian children with World Health Organization-defined CM (n = 55), uncomplicated malaria (UM; n = 20), and healthy controls (HCs; n = 25). Urine GCX breakdown products [glycosaminoglycans (GAGs)] were quantified using dimethylmethylene blue (DMMB) and liquid chromatography-tandem mass spectrometry assays. DMMB-GAG and mass spectrometry (MS)-GAG (g/mol creatinine) were increased in CM and UM compared with HCs (P < 0.001), with no differences in DMMB-GAG and MS-GAG between CM and UM children or between those with and without a fatal outcome. In CM survivors, urinary GCX DMMB-GAG normalized by d 3. After adjusting for disease severity, DMMB-GAG was significantly associated with parasitemia [partial correlation coefficient (Pcorr) = 0.34; P = 0.01] and plasma TNF (Pcorr = 0.26; P = 0.04) and inversely with plasma and urine NO oxidation products [Pcorr = -0.31 (P = 0.01) and Pcorr = -0.26 (P = 0.03), respectively]. GCX breakdown is increased in children with falciparum malaria, with similar elevations in CM and UM. Endothelial GCX degradation may impair endothelial NO production, exacerbate adhesion-molecule expression, exposure, and parasite sequestration, and contribute to malaria pathogenesis.-Yeo, T. W., Bush, P. A., Chen, Y., Young, S. P., Zhang, H., Millington, D. S., Granger, D. L., Mwaikambo, E. D., Anstey, N. M., Weinberg, J. B. Glycocalyx breakdown is increased in African children with cerebral and uncomplicated falciparum malaria.
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Affiliation(s)
- Tsin W Yeo
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore.,National Centre for Infectious Diseases, Tan Tock Seng Hospital, Singapore.,Menzies School of Health Research, Charles Darwin University, Darwin, Northern Territory, Australia
| | - Peggy A Bush
- Duke University-Veterans Affairs (VA) Medical Center, Durham, North Carolina, USA
| | - Youwei Chen
- Duke University-Veterans Affairs (VA) Medical Center, Durham, North Carolina, USA
| | - Sarah P Young
- Duke University-Veterans Affairs (VA) Medical Center, Durham, North Carolina, USA
| | - Haoyue Zhang
- Duke University-Veterans Affairs (VA) Medical Center, Durham, North Carolina, USA
| | - David S Millington
- Duke University-Veterans Affairs (VA) Medical Center, Durham, North Carolina, USA
| | - Donald L Granger
- University of Utah-Veterans Affairs (VA) Medical Center, Salt Lake City, Utah, USA
| | | | - Nicholas M Anstey
- Menzies School of Health Research, Charles Darwin University, Darwin, Northern Territory, Australia
| | - J Brice Weinberg
- Duke University-Veterans Affairs (VA) Medical Center, Durham, North Carolina, USA
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The Plasmodium falciparum transcriptome in severe malaria reveals altered expression of genes involved in important processes including surface antigen-encoding var genes. PLoS Biol 2018; 16:e2004328. [PMID: 29529020 PMCID: PMC5864071 DOI: 10.1371/journal.pbio.2004328] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Revised: 03/22/2018] [Accepted: 02/16/2018] [Indexed: 01/13/2023] Open
Abstract
Within the human host, the malaria parasite Plasmodium falciparum is exposed to multiple selection pressures. The host environment changes dramatically in severe malaria, but the extent to which the parasite responds to-or is selected by-this environment remains unclear. From previous studies, the parasites that cause severe malaria appear to increase expression of a restricted but poorly defined subset of the PfEMP1 variant, surface antigens. PfEMP1s are major targets of protective immunity. Here, we used RNA sequencing (RNAseq) to analyse gene expression in 44 parasite isolates that caused severe and uncomplicated malaria in Papuan patients. The transcriptomes of 19 parasite isolates associated with severe malaria indicated that these parasites had decreased glycolysis without activation of compensatory pathways; altered chromatin structure and probably transcriptional regulation through decreased histone methylation; reduced surface expression of PfEMP1; and down-regulated expression of multiple chaperone proteins. Our RNAseq also identified novel associations between disease severity and PfEMP1 transcripts, domains, and smaller sequence segments and also confirmed all previously reported associations between expressed PfEMP1 sequences and severe disease. These findings will inform efforts to identify vaccine targets for severe malaria and also indicate how parasites adapt to-or are selected by-the host environment in severe malaria.
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