Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0024530 (malaria)
 44,886 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Various molecules expressed on the surface of platelets have been shown to mediate the protective or deleterious role of these cells in immuno-inflammatory mechanisms. Increasing evidence points to the involvement of the cell adhesion molecules, gpIIb-IIIa, P-selectin, CD31, LFA-1, and CD36 in the interaction between platelets and endothelial cells as well as other cell types. The possible role of these molecules in the ability of platelets to support endothelium and to protect against tumour necrosis factor mediated cytolysis or parasitic invasion are reviewed. The involvement of platelets as effectors of tissue damage in cerebral malaria, lipopolysaccharide induced pathology, and pulmonary fibrosis is also discussed. This has then been extended to include the intercellular mechanisms underpinning their pathogenic role in metastasis, transplant rejection, stroke, brain hypoxia, and related conditions. A better understanding of the complex regulation and hierarchical organisation of these various platelet adhesion molecules may prove useful in the development of new approaches to the treatment of such diseases.
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PMID:Role of platelet adhesion in homeostasis and immunopathology. 935 Mar

Excessive binding of Plasmodium falciparum-infected red blood cells (pRBCs) to the vascular endothelium (cytoadherence) and to uninfected erythrocytes (rosetting) may lead to occlusion of the microvasculature and thereby contribute directly to the acute pathology of severe human malaria. A number of endothelial receptors have been identified as targets for the pRBCs, including CD36, intercellular adhesion molecule-1 (ICAM-1) and chondroitin-4-sulfate (CSA). In vitro, CD36 is the most frequent target of strains from patients with mild as well as severe P. falciparum malaria, but is expressed at low levels on the cerebral microvasculature and therefore seems unlikely to be involved in the evolution of cerebral disease. Strains of P. falciparum that form rosettes are associated both with the occurrence of cerebral malaria and severe anemia. Here we report that malaria-infected RBCs adhere to platelet/endothelial cell adhesion molecule-1 (PECAM-1/CD31) on the vascular endothelium. pRBCs bind to endothelial cells, to PECAM-1/CD31 transfected cells, and directly to recombinant PECAM-1/CD31 absorbed onto plastic. Soluble PECAM-1/CD31 and monoclonal antibodies specific for the amino-terminal segment of PECAM-1/CD31 (domains 1-4) blocked the binding. Interferon-gamma (IFN-gamma)-essential for the development of cerebral malaria in the mouse-was found to augment adhesion of human pRBCs to PECAM-1/CD31 on endothelial cell monolayers. Our results suggest that PECAM-1/CD31 is a virulence-associated endothelial receptor of P. falciparum-infected RBCs.
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PMID:PECAM-1/CD31, an endothelial receptor for binding Plasmodium falciparum-infected erythrocytes. 939 93

Patients infected with the malaria parasite Plasmodium falciparum may develop a diffuse reversible encephalopathy, termed cerebral malaria. It is unclear how the intraerythrocytic parasite, which sequesters in the cerebral microvasculature but does not enter the brain parenchyma, induces this neurological syndrome. Adhesion of parasitized red blood cells in the brain microvasculature is mediated by specific receptors on the host endothelium, including intercellular adhesion molecule (ICAM)-1, CD36 and CD31. Leucocyte binding to cerebral endothelial cells in culture induces intracellular signalling via ICAM-1. The hypothesis that parasitized red blood cells binding to receptors on cerebral endothelial cells causes changes in the integrity of the blood-brain barrier was tested. Immunohistochemistry was used to examine the blood-brain barrier in human cerebral malaria, with antibodies to macrophage and endothelial activation markers, intercellular junction proteins, and plasma proteins. The distribution of the cell junction proteins occludin, vinculin and ZO-1 were altered in cerebral malaria cases compared to controls. While fibrinogen was the only plasma protein detected in the perivascular space, there was widespread perivascular macrophage activation, suggesting that these cells had been exposed to plasma proteins. It was concluded that functional changes to the blood-brain barrier occur in cerebral malaria, possibly as a result of the binding of parasitized red blood cells to cerebral endothelial cells. These changes require further examination in vitro.
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PMID:Evidence of blood-brain barrier dysfunction in human cerebral malaria. 1047 50

Erythrocytes infected with mature forms of Plasmodium falciparum do not circulate but are withdrawn from the peripheral circulation; they are bound to the endothelial lining and to uninfected erythrocytes in the microvasculature. Blockage of the blood flow, hampered oxygen delivery, and severe malaria may follow if binding is excessive. The NH(2)-terminal head structure (Duffy binding-like domain 1 [DBL1alpha]-cysteine-rich interdomain region [CIDR1alpha]) of a single species of P. falciparum erythrocyte membrane protein 1 (PfEMP1) is here shown to mediate adherence to multiple host receptors including platelet-endothelial cell adhesion molecule 1 (PECAM-1)/CD31, the blood group A antigen, normal nonimmune immunoglobulin M, three virulence-associated receptor proteins, a heparan sulfate-like glucosaminoglycan, and CD36. DBL2delta was found to mediate additional binding to PECAM-1/CD31. The exceptional binding activity of the PfEMP1 head structure and its relatively conserved nature argues that it holds an important role in erythrocyte sequestration and therefore in the virulence of the malaria parasite.
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PMID:The semiconserved head structure of Plasmodium falciparum erythrocyte membrane protein 1 mediates binding to multiple independent host receptors. 1088 May 21

Adhesion molecules on endothelial cells are known to be important ligands for malaria infected red blood cells (PRBC) [Mol Biochem Parasitol, 76, (1996) 1], and may be involved in the pathogenic process of cerebral malaria (CM) which is the most serious complication of falciparum malaria, through enhancing micro embolism or sequestration in the capillaries of the brain. PECAM-1/CD31 is one of these candidate ligands and is coded by a polymorphic gene. Two hundred and ten Thai malaria patients (43 cerebral, 89 severe and 78 uncomplicated) were analyzed for their genetic polymorphism of CD31 to examine the clinical relationship between the disease and specific genotypes. Four alleles were defined 125 valine (V)-563 asparagine (N); 125V-563 serine (S); 125 leucine (L)-563N; and 125L-563S. We found that the frequency of the 125 V/V 563 N/N genotype was significantly high in CM patients as compared with severe cases without CM (P<0.01, OR=2.92), suggesting that this genotype is one of the risk factors for CM.
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PMID:Association of adhesion molecule PECAM-1/CD31 polymorphism with susceptibility to cerebral malaria in Thais. 1171 9

Platelet-endothelial cell adhesion molecule 1 (PECAM-1/CD31) has been identified as an endothelial cell receptor of Plasmodium falciparum-infected erythrocytes. The significance of adhesion of infected erythrocytes to this receptor in malaria infection has not been determined. We have therefore studied the association of the functional mutation CTG-->GTG (Leu-->Val) in codon 125 of the Cd31 gene with severe disease in 2 case-control studies of malaria in Madang Hospital, Papua New Guinea, and in Kilifi District Hospital, Kenya. We analyzed data from 442 cases and controls from Papua New Guinea and data from 396 cases and controls from Kenya. The codon 125 polymorphism was not associated with severe malaria in either study. We conclude that the presence of CTG-->GTG (Leu-->Val) substitution in codon 125 in CD31 is not associated with protection from severe malaria, and we suggest that selective forces other than malaria may maintain this high-frequency polymorphism.
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PMID:Short report: codon 125 polymorphism of CD31 and susceptibility to malaria. 1179 67

Plasmodium falciparum may cause severe forms of malaria when excessive sequestration of infected and uninfected erythrocytes occurs in vital organs. The capacity of wild-type isolates of P falciparum-infected erythrocytes (parasitized red blood cells [pRBCs]) to bind glycosaminoglycans (GAGs) such as heparin has been identified as a marker for severe disease. Here we report that pRBCs of the parasite FCR3S1.2 and wild-type clinical isolates from Uganda adhere to heparan sulfate (HS) on endothelial cells. Binding to human umbilical vein endothelial cells (HUVECs) and to human lung endothelial cells (HLECs) was found to be inhibited by HS/heparin or enzymes that remove HS from cell surfaces. (35)S-labeled HS extracted from HUVECs bound directly to the pRBCs' membrane. Using recombinant proteins corresponding to the different domains of P falciparum erythrocyte membrane protein 1 (PfEMP1), we identified Duffy-binding-like domain-1alpha (DBL1alpha) as the ligand for HS. DBL1alpha bound in an HS-dependent way to endothelial cells and blocked the adherence of pRBCs in a dose-dependent manner. (35)S-labeled HS bound to DBL1alpha-columns and eluted as a distinct peak at 0.4 mM NaCl. (35)S-labeled chondroitin sulfate (CS) of HUVECs did not bind to PfEMP1 or to the pRBCs' membrane. Adhesion of pRBCs of FCR3S1.2 to platelet endothelial cell adhesion molecule-1 (PECAM-1)/CD31, mediated by the cysteine-rich interdomain region 1alpha (CIDR1alpha), was found be operative with, but independent of, the binding to HS. HS and the previously identified HS-like GAG on uninfected erythrocytes may act as coreceptors in endothelial and erythrocyte binding of rosetting parasites, causing excessive sequestration of both pRBCs and RBCs.
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PMID:Heparan sulfate on endothelial cells mediates the binding of Plasmodium falciparum-infected erythrocytes via the DBL1alpha domain of PfEMP1. 1243 89

It is proposed that the surface ligands of Plasmodium falciparum infected HbAS erythrocytes, not like infected HbAA erythrocytes, are altered due to the sickling that soon takes place once a HbAS erythrocyte gets infected with P. falciparum parasite. This alteration modulates cytoadherence and/or binding of the sickled erythrocytes to the peripheral blood mononuclear cells (PBMCs). Both cytoadherence and binding to PBMCs are responsible for the pathogenesis of malaria. Therefore, subjects of the HbAS genotype experience mild symptoms of malaria. The hypothesis could be tested in vitro by comparing the binding of P. falciparum infected HbAS and HbAA erythrocytes to platelet-endothelial cell adhesion molecule-1 (CD31) and by comparing the levels of tumor necrosis factor (TNF) and interferon gamma (IFN-gamma) following in vitro stimulation of PBMCs by HbAS and HbAA infected erythrocytes.
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PMID:Protection against severe clinical manifestations of Plasmodium falciparum malaria among sickle cell trait subjects is due to modification of the release of cytokines and/or cytoadherence of infected erythrocytes to the host vascular beds. 1269 25

The Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) antigens play a major role in cytoadhesion of infected erythrocytes (IE), antigenic variation, and immunity to malaria. The current consensus on control of variant surface antigen expression is that only one PfEMP1 encoded by one var gene is expressed per cell at a time. We measured var mRNA transcript levels by real-time Q-PCR, analysed var gene transcripts by single-cell FISH and directly compared these with PfEMP1 antigen surface expression and cytoadhesion in three different antibody-selected P. falciparum 3D7 sub-lines using live confocal microscopy, flow cytometry and in vitro adhesion assays. We found that one selected parasite sub-line simultaneously expressed two different var genes as surface antigens, on single IE. Importantly, and of physiological relevance to adhesion and malaria pathogenesis, this parasite sub-line was found to bind both CD31/PECAM1 and CD54/ICAM1 and to adhere twice as efficiently to human endothelial cells, compared to infected cells having only one PfEMP1 variant on the surface. These new results on PfEMP1 antigen expression indicate that a re-evaluation of the molecular mechanisms involved in P. falciparum adhesion and of the accepted paradigm of absolutely mutually exclusive var gene transcription is required.
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PMID:Surface co-expression of two different PfEMP1 antigens on single plasmodium falciparum-infected erythrocytes facilitates binding to ICAM1 and PECAM1. 2082 88

The Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) family plays a central role in antigenic variation and cytoadhesion of P. falciparum infected erythrocytes. PfEMP1 proteins/var genes are classified into three main subfamilies (UpsA, UpsB, and UpsC) that are hypothesized to have different roles in binding and disease. To investigate whether these subfamilies have diverged in binding specificity and test if binding could be predicted by adhesion domain classification, we generated a panel of 19 parasite lines that primarily expressed a single dominant var transcript and assayed binding against 12 known host receptors. By limited dilution cloning, only UpsB and UpsC var genes were isolated, indicating that UpsA var gene expression is rare under in vitro culture conditions. Consequently, three UpsA variants were obtained by rosette purification and selection with specific monoclonal antibodies to create a more representative panel. Binding assays showed that CD36 was the most common adhesion partner of the parasite panel, followed by ICAM-1 and TSP-1, and that CD36 and ICAM-1 binding variants were highly predicted by adhesion domain sequence classification. Binding to other host receptors, including CSA, VCAM-1, HABP1, CD31/PECAM, E-selectin, Endoglin, CHO receptor "X", and Fractalkine, was rare or absent. Our findings identify a category of larger PfEMP1 proteins that are under dual selection for ICAM-1 and CD36 binding. They also support that the UpsA group, in contrast to UpsB and UpsC var genes, has diverged from binding to the major microvasculature receptor CD36 and likely uses other mechanisms to sequester in the microvasculature. These results demonstrate that CD36 and ICAM-1 have left strong signatures of selection on the PfEMP1 family that can be detected by adhesion domain sequence classification and have implications for how this family of proteins is specializing to exploit hosts with varying levels of anti-malaria immunity.
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PMID:Investigating the host binding signature on the Plasmodium falciparum PfEMP1 protein family. 2157 38


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