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Holmberg V, Onkamo P, Lahtela E, Lahermo P, Bedu-Addo G, Mockenhaupt FP, Meri S. Mutations of complement lectin pathway genes MBL2 and MASP2 associated with placental malaria. Malar J 2012; 11:61. [PMID: 22380611 PMCID: PMC3320545 DOI: 10.1186/1475-2875-11-61] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2011] [Accepted: 03/02/2012] [Indexed: 01/30/2023] Open
Abstract
Background Innate immunity plays a crucial role in the host defense against malaria including Plasmodium falciparum malaria in pregnancy, but the roles of the various underlying genes and mechanisms predisposing to the disease are poorly understood. Methods 98 single-nucletoide polymorphisms were genotyped in a set of 17 functionally related genes of the complement system in 145 primiparous Ghanaian women with placental malaria, defined by placental parasitaemia or malaria pigment, and as a control, in 124 non-affected primiparae. Results Placental malaria was significantly associated with SNPs in the lectin pathway genes MBL2, MASP2, FCN2 and in properdin. In particular, the main African mannose-binding lectin deficiency variant (MBL2*G57E, rs1800451) increased the odds of placental malaria (OR 1.6; permuted p-value 0.014). In contrast, a common MASP2 mutation (R439H, rs12085877), which reduces the activity of MBL-MASP2 complexes occurred in 33% of non-affected women and in 22% primiparae with placental malaria (OR 0.55, permuted p-value 0.020). Conclusions Excessive complement activation is of importance in the pathogenesis of placental malaria by mediating inflammation, coagulation, and endothelial dysfunction. Mutated MBL and MASP2 proteins could have direct intrinsic effects on the susceptibility to placental malaria, in addition to their roles in regulation of downstream complement activation.
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Affiliation(s)
- Ville Holmberg
- Department of Bacteriology and Immunology, University of Helsinki, Helsinki, Finland.
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Kane EG, Taylor-Robinson AW. Prospects and Pitfalls of Pregnancy-Associated Malaria Vaccination Based on the Natural Immune Response to Plasmodium falciparum VAR2CSA-Expressing Parasites. Malar Res Treat 2012; 2011:764845. [PMID: 22363896 PMCID: PMC3272661 DOI: 10.4061/2011/764845] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2011] [Revised: 11/28/2011] [Accepted: 11/30/2011] [Indexed: 01/05/2023] Open
Abstract
Pregnancy-associated malaria, a manifestation of severe malaria, is the cause of up to 200,000 infant deaths a year, through the effects of placental insufficiency leading to growth restriction and preterm delivery. Development of a vaccine is one strategy for control. Plasmodium falciparum-infected red blood cells accumulate in the placenta through specific binding of pregnancy-associated parasite variants that express the VAR2CSA antigen to chondroitin sulphate A on the surface of syncytiotrophoblast cells. Parasite accumulation, accompanied by an inflammatory infiltrate, disrupts the cytokine balance of pregnancy with the potential to cause placental damage and compromise foetal growth. Multigravid women develop immunity towards VAR2CSA-expressing parasites in a gravidity-dependent manner which prevents unfavourable pregnancy outcomes. Although current vaccine design, targeting VAR2CSA antigens, has succeeded in inducing antibodies artificially, this candidate may not provide protection during the first trimester and may only protect those women living in areas endemic for malaria. It is concluded that while insufficient information about placental-parasite interactions is presently available to produce an effective vaccine, incremental progress is being made towards achieving this goal.
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Affiliation(s)
- Elizabeth G. Kane
- Institute of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
- Faculty of Medicine, University of Liverpool, Liverpool L69 3GA, UK
| | - Andrew W. Taylor-Robinson
- Institute of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
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Conroy AL, Liles WC, Molyneux ME, Rogerson SJ, Kain KC. Performance characteristics of combinations of host biomarkers to identify women with occult placental malaria: a case-control study from Malawi. PLoS One 2011; 6:e28540. [PMID: 22174834 PMCID: PMC3236186 DOI: 10.1371/journal.pone.0028540] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2011] [Accepted: 11/10/2011] [Indexed: 12/31/2022] Open
Abstract
Background Because of its propensity to sequester in the placental intervillous space, Plasmodium falciparum can evade detection by peripheral smear in women with placental malaria (PM). We evaluated host biomarkers as potential indicators of occult PM infections. Methods and Findings Using a case-control design, we evaluated the ability of biomarkers to identify PM in the absence of circulating peripheral parasites (n = 24) compared to placental smear-negative controls (n = 326). We measured levels of biomarkers (C3a, C5a, CRP, angiopoietin-1, angiopoietin-2, sTie-2, sEndoglin, VEGF, sFlt-1, tissue factor, and leptin) in maternal peripheral plasma at delivery. Using ROC curve analysis, we assessed the ability of clinical parameters and biomarkers to accurately detect PM infections identified by placental smear. We show that decreases in sFlt-1 and leptin and increases in CRP were associated with occult PM infections (p<0.01) and correlated with placental parasitaemia (p<0.01). Individually, all markers had moderate ability to diagnose occult PM infections with areas under the ROC between 0.62 and 0.72. In order to improve diagnostic performance, we generated simple scoring systems to identify PM infections using either a clinical score (0–2), a biomarker score (0–3) or a clinical plus biomarker score (0–5). The combinatorial model that incorporated both clinical parameters and biomarkers had an area under curve (AUC) of 0.85 (95% CI, 0.81-0.89), which was significantly better at identifying occult PM infections than the clinical score alone (p = 0.001). Conclusion These data suggest that host biomarkers in the maternal peripheral blood may improve the detection of PM in the absence of peripheral parasitaemia.
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Affiliation(s)
- Andrea L. Conroy
- Sandra A. Rotman Laboratories, McLaughlin-Rotman Centre for Global Health, University Health Network-Toronto General Hospital, University of Toronto, Toronto, Ontario, Canada
| | - W. Conrad Liles
- Sandra A. Rotman Laboratories, McLaughlin-Rotman Centre for Global Health, University Health Network-Toronto General Hospital, University of Toronto, Toronto, Ontario, Canada
- Tropical Disease Unit, Division of Infectious Diseases, Department of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Malcolm E. Molyneux
- Malawi-Liverpool-Wellcome Trust Clinical Research Programme, Blantyre, Malawi
- College of Medicine, University of Malawi, Blantyre, Malawi
- School of Tropical Medicine, University of Liverpool, Liverpool, United Kingdom
| | - Stephen J. Rogerson
- Department of Medicine, University of Melbourne, Royal Melbourne Hospital, Parkville, Victoria, Australia
| | - Kevin C. Kain
- Sandra A. Rotman Laboratories, McLaughlin-Rotman Centre for Global Health, University Health Network-Toronto General Hospital, University of Toronto, Toronto, Ontario, Canada
- Tropical Disease Unit, Division of Infectious Diseases, Department of Medicine, University of Toronto, Toronto, Ontario, Canada
- * E-mail:
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Mullick A, Tremblay J, Leon Z, Gros P. A novel role for the fifth component of complement (C5) in cardiac physiology. PLoS One 2011; 6:e22919. [PMID: 21829669 PMCID: PMC3148243 DOI: 10.1371/journal.pone.0022919] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2011] [Accepted: 07/09/2011] [Indexed: 12/17/2022] Open
Abstract
We have previously demonstrated that C5-deficient A/J and recombinant congenic BcA17 mice suffer from cardiac dysfunction when infected with C. albicans blastospores intravenously. During these studies we had observed that, even in the control un-infected state, BcA17 hearts displayed alterations in gene expression that have been associated with pathological cardiac hypertrophy in comparison to parental C5-sufficient C57Bl/6J (B6) mice. Of note was an increase in the expression of Nppb, a member of the fetal gene program and a decrease in the expression of Rgs2, an inhibitor of the hypertrophic response. We now report that C5-deletion has also affected the expression of other elements of the fetal gene program. Moreover deleting the C5a receptor, C5aR, has essentially the same effect as deleting C5, indicating a key role for C5a-C5aR signaling in the phenotype. Having noted a pathological phenotype in the un-infected state, we investigated the role of C5 in the response to cardiac stress. In previous studies, comparison of the expression profiles of C. albicans-infected BcA17 and similarly infected B6 hearts had revealed a paucity of cardioprotective genes in the C5-deficient heart. To determine whether this was also directly linked to C5-deficiency, we tested the expression of 5 such genes in the C. albicans-infected C5aR(-/-) mice. We found again that deletion of C5aR recapitulated the alterations in stress response of BcA17. To determine whether our observations were relevant to other forms of cardiac injury, we tested the effect of C5-deficiency on the response to isoproterenol-induced hypertrophic stimulation. Consistent with our hypothesis, A/J, BcA17 and C5aR(-/-) mice responded with higher levels of Nppa expression than B6 and BALB/c mice. In conclusion, our results suggest that an absence of functional C5a renders the heart in a state of distress, conferring a predisposition to cardiac dysfunction in the face of additional injury.
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Affiliation(s)
- Alaka Mullick
- Biotechnology Research Institute, Montréal, Québec, Canada.
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Complement activation: a critical mediator of adverse fetal outcomes in placental malaria? Trends Parasitol 2011; 27:294-9. [DOI: 10.1016/j.pt.2011.02.005] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2010] [Revised: 02/17/2011] [Accepted: 02/22/2011] [Indexed: 11/19/2022]
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Ramos TN, Darley MM, Hu X, Billker O, Rayner JC, Ahras M, Wohler JE, Barnum SR. Cutting edge: the membrane attack complex of complement is required for the development of murine experimental cerebral malaria. THE JOURNAL OF IMMUNOLOGY 2011; 186:6657-60. [PMID: 21572031 DOI: 10.4049/jimmunol.1100603] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Cerebral malaria is the most severe complication of Plasmodium falciparum infection and accounts for a large number of malaria fatalities worldwide. Recent studies demonstrated that C5(-/-) mice are resistant to experimental cerebral malaria (ECM) and suggested that protection was due to loss of C5a-induced inflammation. Surprisingly, we observed that C5aR(-/-) mice were fully susceptible to disease, indicating that C5a is not required for ECM. C3aR(-/-) and C3aR(-/-) × C5aR(-/-) mice were equally susceptible to ECM as were wild-type mice, indicating that neither complement anaphylatoxin receptor is critical for ECM development. In contrast, C9 deposition in the brains of mice with ECM suggested an important role for the terminal complement pathway. Treatment with anti-C9 Ab significantly increased survival time and reduced mortality in ECM. Our data indicate that protection from ECM in C5(-/-) mice is mediated through inhibition of membrane attack complex formation and not through C5a-induced inflammation.
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Affiliation(s)
- Theresa N Ramos
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
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Umbers AJ, Aitken EH, Rogerson SJ. Malaria in pregnancy: small babies, big problem. Trends Parasitol 2011; 27:168-75. [PMID: 21377424 DOI: 10.1016/j.pt.2011.01.007] [Citation(s) in RCA: 152] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2010] [Revised: 01/24/2011] [Accepted: 01/27/2011] [Indexed: 11/28/2022]
Abstract
Placental malaria is hypothesized to lead to placental insufficiency, which causes fetal growth restriction (FGR). In this review, recent discoveries regarding the mechanisms of pathogenesis by which malaria causes FGR are discussed in the wider context of placental function and fetal growth. Placental malaria and associated host responses can induce changes in placental structure and function, affecting pregnancy-associated growth-regulating hormones and predisposing the offspring to hypertension and vascular dysfunction. Risk factors associated with FGR are highlighted, and potential interventions and studies to uncover remaining mechanisms of pathogenesis are proposed. Together, these strategies aim to decrease the burden of FGR associated with malaria in pregnancy.
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Affiliation(s)
- Alexandra J Umbers
- Department of Medicine (Royal Melbourne Hospital), The University of Melbourne, Post Office Royal Melbourne Hospital, Parkville, VIC 3050, Australia
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Silver KL, Higgins SJ, McDonald CR, Kain KC. Complement driven innate immune response to malaria: fuelling severe malarial diseases. Cell Microbiol 2010; 12:1036-45. [PMID: 20545944 DOI: 10.1111/j.1462-5822.2010.01492.x] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Severe malaria remains a major cause of global mortality. The innate immune response to infection is a key determinant of malaria severity and outcome. The complement system plays a key role in initiating and augmenting innate immune responses, including inflammation, endothelial activation, opsonization and coagulation, processes which have been implicated in malaria pathogenesis. In this review, we discuss the evidence supporting a role for excessive complement activation in the pathogenesis of severe malaria.
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Affiliation(s)
- Karlee L Silver
- McLaughlin-Rotman Centre for Global Health, University Health Network-Toronto General Hospital, University of Toronto, Toronto, ON, Canada
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Wang Y, Yang YX. Advances in understanding the role of complement in the pathogenesis of fatty liver disease. Shijie Huaren Xiaohua Zazhi 2010; 18:1577-1581. [DOI: 10.11569/wcjd.v18.i15.1577] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Patients with fatty liver disease (FLD) exhibit various immunologic abnormalities in the adipose tissue and the liver. Complement plays an important role in the development of FLD. Innate immune dysfunction in the adipose tissue can lead to abnormal production of adipose-derived factors, some of which can activate complement. Complement can not only amplify the inflammatory response and lead to mitochondrial damage, but also inhibit hepatic fat disposal and promote lipid accumulation in hepatocytes. An exploration of the relationship between complement ant the liver can help us have a deep understanding of the mechanisms underlying the pathogenesis of FLD. The antagonists of the C5L2 receptor provide us potential new medicines for FLD. A further study of the role of complement in stress-induced liver remodeling can help clarify the role of complement in the development and progression of FLD.
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Lynch AM, Salmon JE. Dysregulated complement activation as a common pathway of injury in preeclampsia and other pregnancy complications. Placenta 2010; 31:561-7. [PMID: 20427084 DOI: 10.1016/j.placenta.2010.03.010] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/11/2009] [Revised: 03/21/2010] [Accepted: 03/25/2010] [Indexed: 11/17/2022]
Abstract
The complement system protects the host against invading organisms, initiates inflammation and dispose of immune complexes and the products of inflammatory injury. The complement system provides an important link between the innate and adaptive immune systems. Experimental observations suggest that increased complement activation causes and/or perpetuates inflammation during pregnancy. Recent studies suggest a link between complement activation and preeclampsia. Excessive activation or insufficient regulation of complement recruits leukocytes and unleashes potent inflammatory and anti-angiogenic mediators associated with placental insufficiency and maternal endothelial dysfunction characteristic of preeclampsia. We review the animal and human studies that link complement activation and pathogenic events in preeclampsia, present evidence that activation of the complement system is associated with the development of preeclampsia and provides new targets to prevent its complications.
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Affiliation(s)
- A M Lynch
- Department of Obstetrics and Gynecology, University of Colorado Denver School of Medicine, Aurora, CO 80045, USA
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Silver KL, Zhong K, Leke RGF, Taylor DW, Kain KC. Dysregulation of angiopoietins is associated with placental malaria and low birth weight. PLoS One 2010; 5:e9481. [PMID: 20208992 PMCID: PMC2830425 DOI: 10.1371/journal.pone.0009481] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2009] [Accepted: 01/31/2010] [Indexed: 01/28/2023] Open
Abstract
Background Placental malaria (PM) is associated with adverse pregnancy outcomes including low birth weight (LBW). However, the precise mechanisms by which PM induces LBW are poorly defined. Based on the essential role of angiopoietin (ANG)-1 and -2 in normal placental vascular development, we hypothesized that PM may result in the dysregulation of angiopoietins and thereby contribute to LBW outcomes. Methods and Findings In a mouse model of PM, we show that Plasmodium berghei ANKA infection of pregnant mice resulted in dysregulated angiopoietin levels and fetal growth restriction. PM lead to decreased ANG-1, increased ANG-2, and an elevated ratio of ANG-2/ANG-1 in the placenta and the serum. These observations were extended to malaria-exposed pregnant women: In a study of primigravid women prospectively followed over the course of pregnancy, Plasmodium falciparum infection was associated with a decrease in maternal plasma ANG-1 levels (P = 0.031) and an increase in the ANG-2:ANG-1 ratio (P = 0.048). ANG-1 levels recovered with successful treatment of peripheral parasitemia (P = 0.010). In a cross-sectional study of primigravidae at delivery, angiopoietin dysregulation was associated with PM (P = 0.002) and LBW (P = 0.041). Women with PM who delivered LBW infants had increased ANG-2:ANG-1 ratios (P = 0.002) compared to uninfected women delivering normal birth weight infants. Conclusions These data support the hypothesis that dysregulation of angiopoietins is associated with PM and LBW outcomes, and suggest that ANG-1 and ANG-2 levels may be clinically informative biomarkers to identify P. falciparum-infected mothers at risk of LBW deliveries.
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Affiliation(s)
- Karlee L. Silver
- McLaughlin-Rotman Centre for Global Health, McLaughlin Centre for Molecular Medicine, University Health Network, University of Toronto, Toronto, Ontario, Canada
| | - Kathleen Zhong
- McLaughlin-Rotman Centre for Global Health, McLaughlin Centre for Molecular Medicine, University Health Network, University of Toronto, Toronto, Ontario, Canada
| | - Rose G. F. Leke
- Faculty of Medicine and Biomedical Sciences, University of Yaoundé 1, Yaoundé, Cameroon
| | - Diane Wallace Taylor
- Department of Biology, Georgetown University, Washington, D.C., United States of America
- Department of Tropical Medicine, John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii, United States of America
| | - Kevin C. Kain
- McLaughlin-Rotman Centre for Global Health, McLaughlin Centre for Molecular Medicine, University Health Network, University of Toronto, Toronto, Ontario, Canada
- Tropical Disease Unit, Division of Infectious Diseases, Department of Medicine, Toronto General Hospital, University of Toronto, Toronto, Ontario, Canada
- * E-mail:
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