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Hollingsworth BA, Aldrich JT, Case CM, DiCarlo AL, Hoffman CM, Jakubowski AA, Liu Q, Loelius SG, PrabhuDas M, Winters TA, Cassatt DR. Immune Dysfunction from Radiation Exposure. Radiat Res 2023; 200:396-416. [PMID: 38152282 PMCID: PMC10751071 DOI: 10.1667/rade-22-00004.1] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2023]
Abstract
The hematopoietic system is highly sensitive to ionizing radiation. Damage to the immune system may result in opportunistic infections and hemorrhage, which could lead to mortality. Inflammation triggered by tissue damage can also lead to additional local or widespread tissue damage. The immune system is responsible for tissue repair and restoration, which is made more challenging when it is in the process of self-recovery. Because of these challenges, the Radiation and Nuclear Countermeasures Program (RNCP) and the Basic Immunology Branch (BIB) under the Division of Allergy, Immunology, and Transplantation (DAIT) within the National Institute of Allergy and Infectious Diseases (NIAID), along with partners from the Biomedical Advanced Research and Development Authority (BARDA), and the Radiation Injury Treatment Network (RITN) sponsored a two-day meeting titled Immune Dysfunction from Radiation Exposure held on September 9-10, 2020. The intent was to discuss the manifestations and mechanisms of radiation-induced immune dysfunction in people and animals, identify knowledge gaps, and discuss possible treatments to restore immune function and enhance tissue repair after irradiation.
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Affiliation(s)
- Brynn A. Hollingsworth
- Radiation and Nuclear Countermeasures Program (RNCP), Division of Allergy, Immunology and Transplantation (DAIT), National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH), Rockville, Maryland
- Current address: Center for Biologics Evaluation and Research (CBER), Food and Drug Administration (FDA), Silver Spring, Maryland
| | | | - Cullen M. Case
- Radiation Injury Treatment Network, Minneapolis, Minnesota
| | - Andrea L. DiCarlo
- Radiation and Nuclear Countermeasures Program (RNCP), Division of Allergy, Immunology and Transplantation (DAIT), National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH), Rockville, Maryland
| | - Corey M. Hoffman
- Biomedical Advanced Research and Development Authority (BARDA), Office of the Assistant Secretary for Preparedness and Response (ASPR), Department of Health and Human Services (HHS), Washington, DC
| | | | - Qian Liu
- Basic Immunology Branch (BIB), Division of Allergy, Immunology and Transplantation (DAIT), National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH), Rockville, Maryland
| | - Shannon G. Loelius
- Biomedical Advanced Research and Development Authority (BARDA), Office of the Assistant Secretary for Preparedness and Response (ASPR), Department of Health and Human Services (HHS), Washington, DC
| | - Mercy PrabhuDas
- Basic Immunology Branch (BIB), Division of Allergy, Immunology and Transplantation (DAIT), National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH), Rockville, Maryland
| | - Thomas A. Winters
- Radiation and Nuclear Countermeasures Program (RNCP), Division of Allergy, Immunology and Transplantation (DAIT), National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH), Rockville, Maryland
| | - David R. Cassatt
- Radiation and Nuclear Countermeasures Program (RNCP), Division of Allergy, Immunology and Transplantation (DAIT), National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH), Rockville, Maryland
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Padhi S, Sarangi S, Nayak N, Barik D, Pati A, Panda AK. Interleukin 17A rs2275913 polymorphism is associated with susceptibility to systemic lupus erythematosus: A meta and trial sequential analysis. Lupus 2022; 31:674-683. [PMID: 35353646 DOI: 10.1177/09612033221090172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND The role of cytokines in the development of systemic lupus erythematosus (SLE) has received much attention. Interleukin-17 A upregulates several inflammation-related genes and is thought to have a crucial role in SLE development. The susceptibility to SLE development has been linked to functional genetic variations of the IL-17A gene; nevertheless, the findings have been conflicting. We conducted a meta-analysis that included previously published reports to establish a definitive conclusion on the role of the IL-17A rs2275913 polymorphism in SLE propensity. MATERIALS AND METHODS The PubMed, Google Scholar, and Scopus databases were used to find eligible published articles. All analyses were conducted using Comprehensive Meta-analysis V3.1. Funnel plots and Egger's regression analysis were used to assess publication bias. Q statistics and I2 test explored the heterogeneity among the included studies. Combined odds ratio, 95% confidence interval were calculated for each comparison model. RESULTS Based on the inclusion and exclusion criteria, a total of four reports, comprising of 608 SLE patients and 815 healthy controls, were considered for the present meta-analysis. The homozygous comparison (AA vs. GG: combined odds ratio= 2.046, p = 0.005) and recessive genetic model (AA vs. GG+GA: combined odds ratio=1.901, p = 0.010) analysis revealed a significant association of rs2275913 with susceptibility to the development of SLE. However, other genetic comparisons (A vs. G, GA vs. GG, AA+GA vs. GG) failed to demonstrate such association. Furthermore, trial sequential analysis revealed a sufficient number of studies, including enough cases and controls that have already been considered to conclude the role of IL17-A rs2275913 polymorphism in SLE. CONCLUSIONS IL-17A rs2275913 polymorphism is associated with susceptibility to SLE development.
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Affiliation(s)
- Sunali Padhi
- Department of Bioscience and Bioinformatics, Berhampur University, Bhanja Bihar, Berhampur, Odisha, India
| | - Surjyapratap Sarangi
- Department of Bioscience and Bioinformatics, Berhampur University, Bhanja Bihar, Berhampur, Odisha, India
| | - Nisha Nayak
- Department of Bioscience and Bioinformatics, Berhampur University, Bhanja Bihar, Berhampur, Odisha, India
| | - Debashis Barik
- Department of Bioscience and Bioinformatics, Berhampur University, Bhanja Bihar, Berhampur, Odisha, India
| | - Abhijit Pati
- Department of Bioscience and Bioinformatics, Berhampur University, Bhanja Bihar, Berhampur, Odisha, India
| | - Aditya K Panda
- Department of Bioscience and Bioinformatics, Berhampur University, Bhanja Bihar, Berhampur, Odisha, India
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Effect of acyl and alkyl analogs of platelet-activating factor on inflammatory signaling. Prostaglandins Other Lipid Mediat 2020; 151:106478. [PMID: 32711129 DOI: 10.1016/j.prostaglandins.2020.106478] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Revised: 07/20/2020] [Accepted: 07/20/2020] [Indexed: 01/11/2023]
Abstract
Platelet-activating factor (PAF), a bioactive ether phospholipid with significant pro-inflammatory properties, was identified almost half a century ago. Despite extensive study of this autocoid, therapeutic strategies for targeting its signaling components have not been successful, including the recent clinical trials with darapladib, a drug that targets plasma PAF-acetylhydrolase (PAF-AH). We recently provided experimental evidence that the previously unrecognized acyl analog of PAF, which is concomitantly produced along with PAF during biosynthesis, dampens PAF signaling by acting both as a sacrificial substrate for PAF-AH and probably as an endogenous PAF-receptor antagonist/partial agonist. If this is the scenario in vivo, PAF-AH needs to catalyze the selective hydrolysis of alkyl-PAF and not acyl-PAF. Accordingly, different approaches are needed for treating inflammatory diseases in which PAF signaling is implicated. The interplay between acyl-PAF, alkyl-PAF, PAF-AH, and PAF-R is complex, and the outcome of this interplay has not been previously appreciated. In this review, we discuss this interaction based on our recent findings. It is very likely that the relative abundance of acyl and alkyl-PAF and their interactions with PAF-R in the presence of their hydrolyzing enzyme PAF-AH may exert a modulatory effect on PAF signaling during inflammation.
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Huang F, Wang K, Shen J. Lipoprotein-associated phospholipase A2: The story continues. Med Res Rev 2019; 40:79-134. [PMID: 31140638 PMCID: PMC6973114 DOI: 10.1002/med.21597] [Citation(s) in RCA: 82] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Revised: 04/20/2019] [Accepted: 04/30/2019] [Indexed: 12/15/2022]
Abstract
Inflammation is thought to play an important role in the pathogenesis of vascular diseases. Lipoprotein-associated phospholipase A2 (Lp-PLA2) mediates vascular inflammation through the regulation of lipid metabolism in blood, thus, it has been extensively investigated to identify its role in vascular inflammation-related diseases, mainly atherosclerosis. Although darapladib, the most advanced Lp-PLA2 inhibitor, failed to meet the primary endpoints of two large phase III trials in atherosclerosis patients cotreated with standard medical care, the research on Lp-PLA2 has not been terminated. Novel pathogenic, epidemiologic, genetic, and crystallographic studies regarding Lp-PLA2 have been reported recently, while novel inhibitors were identified through a fragment-based lead discovery strategy. More strikingly, recent clinical and preclinical studies revealed that Lp-PLA2 inhibition showed promising therapeutic effects in diabetic macular edema and Alzheimer's disease. In this review, we not only summarized the knowledge of Lp-PLA2 established in the past decades but also emphasized new findings in recent years. We hope this review could be valuable for helping researchers acquire a much deeper insight into the nature of Lp-PLA2, identify more potent and selective Lp-PLA2 inhibitors, and discover the potential indications of Lp-PLA2 inhibitors.
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Affiliation(s)
- Fubao Huang
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica (SIMM), Chinese Academy of Sciences, Shanghai, China.,School of Pharmacy, University of Chinese Academy of Sciences, Beijing, China
| | - Kai Wang
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica (SIMM), Chinese Academy of Sciences, Shanghai, China
| | - Jianhua Shen
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica (SIMM), Chinese Academy of Sciences, Shanghai, China
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Gurung AB, Bhattacharjee A. Impact of a non-synonymous Q281R polymorphism on structure of human Lipoprotein-Associated Phospholipase A 2 (Lp-PLA 2 ). J Cell Biochem 2018; 119:7009-7021. [PMID: 29737567 DOI: 10.1002/jcb.26909] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2017] [Accepted: 03/28/2018] [Indexed: 01/27/2023]
Abstract
Non-synonymous single nucleotide polymorphisms (nsSNPs) are genetic variations at single base resulting in an amino acid change which have been associated with various complex human diseases. The human Lipoprotein-associated phospholipase A2 (Lp-PLA2 ) gene harbours a rare Q281R polymorphism which was previously reported to cause loss of enzymatic function. Lp-PLA2 is an important enzyme which catalyzes the hydrolysis of polar phospholipids releasing pro-atherogenic and pro-inflammatory mediators involved in the pathogenesis of atherosclerosis. Our current study is aimed at elucidating the structural and functional consequences of Q281R polymorphism on Lp-PLA2 . The Q281R mutation is classified as deleterious and causes protein instability as deduced from evolutionary, folding free energy changes and Support vector machine (SVM)-based methods. A Q281R mutant structure was deciphered using homology modelling approach and was validated using phi and psi dihedral angles distribution, ERRAT, Verify_3D scores, Protein Structure Analysis (ProSA) energ,y and Z-score. A decreased hydrophobic interactions and weaker substrate binding affinity was observed in the mutant compared to the wild- type (WT) using molecular docking. Further, the mutant displayed enhanced structural flexibility particularly in the low density lipoprotein (LDL) binding domain, decreased solvent accessibility of catalytic residues-Phe274 and Ser273 and increased Cɑ distance between Phe274 and Leu153 and large conformational entropy change as inferred from all-atom molecular dynamics (MD) simulation and essential dynamics (ED) studies. Our results corroborate well with previous experimental studies and thus these aberrations in the Q281R mutant structure may help explain the molecular basis of loss of enzyme activity.
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Affiliation(s)
- Arun B Gurung
- Computational Biology Laboratory, Department of Biotechnology and Bioinformatics, North-Eastern Hill University, Shillong, Meghalaya, India
| | - Atanu Bhattacharjee
- Computational Biology Laboratory, Department of Biotechnology and Bioinformatics, North-Eastern Hill University, Shillong, Meghalaya, India.,Bioinformatics Centre, North-Eastern Hill University, Shillong, Meghalaya, India
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Abstract
The structure of plasma PAF-AH was solved to a resolution of 1.5Å using X-ray crystallography. The enzyme has a classic α/β serine hydrolase fold containing a catalytic triad of Ser273, Asp296, and His351. A hydrophobic patch of the enzyme involving two α-helices (114-126 and 362-369) and neighboring residues have been shown to be essential for lipoprotein particle binding by mutagenesis and mass spectrometry hydrogen/deuterium exchange experiments. An interface-bound model of the enzyme positions the active site above the hydrophobic-hydrophilic interface and is consistent with the known substrate specificity of the enzyme. Several ligand-bound structures of plasma PAF-AH have been solved with organophosphorus compounds and modeled with competitive inhibitors of high affinity and selectivity. This chapter presents an overview of the structure of plasma PAF-AH, molecular details of its functional role, and the interaction of the enzyme with lipoprotein particles.
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Plasma PAF-AH (PLA2G7): Biochemical Properties, Association with LDLs and HDLs, and Regulation of Expression. Enzymes 2015; 38:71-93. [PMID: 26612648 DOI: 10.1016/bs.enz.2015.09.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
This chapter is focused on the plasma form of PAF-acetylhydrolase (PAF-AH), a lipoprotein-bound, calcium-independent phospholipase A2 activity also referred to as lipoprotein-associated phospholipase A2 and PLA2G7. PAF-AH catalyzes the removal of the acyl group at the sn-2 position of PAF and truncated phospholipids generated in settings of inflammation and oxidant stress. Here, I discuss current knowledge related to the structural features of this enzyme, including the molecular basis for association with lipoproteins and susceptibility to oxidative inactivation. The circulating form of PAF-AH is constitutively active and its expression is upregulated by mediators of inflammation at the transcriptional level. Several new mechanisms of regulation have been identified in recent years, including effects mediated by PPARs, VEGFR, and the state of cellular differentiation. Moreover, I discuss recent studies describing significant variations in the structure and regulation of PAF-AH from diverse species, which is likely to have important implications for the function of this enzyme in vivo.
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Rosenson RS, Stafforini DM. Modulation of oxidative stress, inflammation, and atherosclerosis by lipoprotein-associated phospholipase A2. J Lipid Res 2012; 53:1767-82. [PMID: 22665167 DOI: 10.1194/jlr.r024190] [Citation(s) in RCA: 115] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Lipoprotein-associated phospholipase A(2) (Lp-PLA(2)), also known as platelet-activating factor acetylhydrolase (PAF-AH), is a unique member of the phospholipase A(2) superfamily. This enzyme is characterized by its ability to specifically hydrolyze PAF as well as glycerophospholipids containing short, truncated, and/or oxidized fatty acyl groups at the sn-2 position of the glycerol backbone. In humans, Lp-PLA(2) circulates in active form as a complex with low- and high-density lipoproteins. Clinical studies have reported that plasma Lp-PLA(2) activity and mass are strongly associated with atherogenic lipids and vascular risk. These observations led to the hypothesis that Lp-PLA(2) activity and/or mass levels could be used as biomarkers of cardiovascular disease and that inhibition of the activity could offer an attractive therapeutic strategy. Darapladib, a compound that inhibits Lp-PLA(2) activity, is anti-atherogenic in mice and other animals, and it decreases atherosclerotic plaque expansion in humans. However, disagreement continues to exist regarding the validity of Lp-PLA(2) as an independent marker of atherosclerosis and a scientifically justified target for intervention. Circulating Lp-PLA(2) mass and activity are associated with vascular risk, but the strength of the association is reduced after adjustment for basal concentrations of the lipoprotein carriers with which the enzyme associates. Genetic studies in humans harboring an inactivating mutation at this locus indicate that loss of Lp-PLA(2) function is a risk factor for inflammatory and vascular conditions in Japanese cohorts. Consistently, overexpression of Lp-PLA(2) has anti-inflammatory and anti-atherogenic properties in animal models. This thematic review critically discusses results from laboratory and animal studies, analyzes genetic evidence, reviews clinical work demonstrating associations between Lp-PLA(2) and vascular disease, and summarizes results from animal and human clinical trials in which administration of darapladib was tested as a strategy for the management of atherosclerosis.
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Grallert H, Dupuis J, Bis JC, Dehghan A, Barbalic M, Baumert J, Lu C, Smith NL, Uitterlinden AG, Roberts R, Khuseyinova N, Schnabel RB, Rice KM, Rivadeneira F, Hoogeveen RC, Fontes JD, Meisinger C, Keaney JF, Lemaitre R, Aulchenko YS, Vasan RS, Ellis S, Hazen SL, van Duijn CM, Nelson JJ, März W, Schunkert H, McPherson RM, Stirnadel-Farrant HA, Psaty BM, Gieger C, Siscovick D, Hofman A, Illig T, Cushman M, Yamamoto JF, Rotter JI, Larson MG, Stewart AF, Boerwinkle E, Witteman JC, Tracy RP, Koenig W, Benjamin EJ, Ballantyne CM. Eight genetic loci associated with variation in lipoprotein-associated phospholipase A2 mass and activity and coronary heart disease: meta-analysis of genome-wide association studies from five community-based studies. Eur Heart J 2012; 33:238-51. [PMID: 22003152 PMCID: PMC3258449 DOI: 10.1093/eurheartj/ehr372] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/16/2010] [Revised: 08/16/2011] [Accepted: 09/09/2011] [Indexed: 12/20/2022] Open
Abstract
AIMS Lipoprotein-associated phospholipase A2 (Lp-PLA2) generates proinflammatory and proatherogenic compounds in the arterial vascular wall and is a potential therapeutic target in coronary heart disease (CHD). We searched for genetic loci related to Lp-PLA2 mass or activity by a genome-wide association study as part of the Cohorts for Heart and Aging Research in Genomic Epidemiology (CHARGE) Consortium. METHODS AND RESULTS In meta-analyses of findings from five population-based studies, comprising 13 664 subjects, variants at two loci (PLA2G7, CETP) were associated with Lp-PLA2 mass. The strongest signal was at rs1805017 in PLA2G7 [P = 2.4 × 10(-23), log Lp-PLA2 difference per allele (beta): 0.043]. Variants at six loci were associated with Lp-PLA2 activity (PLA2G7, APOC1, CELSR2, LDL, ZNF259, SCARB1), among which the strongest signals were at rs4420638, near the APOE-APOC1-APOC4-APOC2 cluster [P = 4.9 × 10(-30); log Lp-PLA2 difference per allele (beta): -0.054]. There were no significant gene-environment interactions between these eight polymorphisms associated with Lp-PLA2 mass or activity and age, sex, body mass index, or smoking status. Four of the polymorphisms (in APOC1, CELSR2, SCARB1, ZNF259), but not PLA2G7, were significantly associated with CHD in a second study. CONCLUSION Levels of Lp-PLA2 mass and activity were associated with PLA2G7, the gene coding for this protein. Lipoprotein-associated phospholipase A2 activity was also strongly associated with genetic variants related to low-density lipoprotein cholesterol levels.
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Affiliation(s)
- Harald Grallert
- Helmholtz Zentrum München, German Research Center for Environmental Health, Institute of Epidemiology, Neuherberg, Germany
| | - Josée Dupuis
- National Heart, Lung, and Blood Institute's and Boston University's Framingham Heart Study, 73 Mount Wayte Ave. Suite 2, Framingham, MA, USA
- Department of Biostatistics, Boston University School of Public Health, Boston, MA, USA
| | - Joshua C. Bis
- Cardiovascular Health Research Unit and Department of Medicine, University of Washington, Seattle, WA, USA
| | - Abbas Dehghan
- Department of Epidemiology, Erasmus University Medical Center, Rotterdam, The Netherlands
- Member of the Netherlands Consortium on Healthy Aging (NCHA), Leiden, The Netherlands
| | - Maja Barbalic
- Human Genetics Center, University of Texas Health Science Center at Houston, Houston, TX, USA
| | - Jens Baumert
- Helmholtz Zentrum München, German Research Center for Environmental Health, Institute of Epidemiology, Neuherberg, Germany
| | - Chen Lu
- Department of Biostatistics, Boston University School of Public Health, Boston, MA, USA
| | - Nicholas L. Smith
- Department of Epidemiology, University of Washington, Seattle, WA, USA
- Seattle Epidemiologic Research and Information Center of the Department of Veterans Affairs Office of Research and Development, Seattle, WA, USA
- Group Health Research Institute, Group Health Cooperative, Seattle, WA, USA
| | - André G. Uitterlinden
- Department of Epidemiology, Erasmus University Medical Center, Rotterdam, The Netherlands
- Member of the Netherlands Consortium on Healthy Aging (NCHA), Leiden, The Netherlands
- Department of Internal Medicine, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Robert Roberts
- John & Jennifer Ruddy Canadian Cardiovascular Genetics Centre, University of Ottawa Heart Institute, Ottawa, Ontario, Canada
| | - Natalie Khuseyinova
- Department of Internal Medicine II–Cardiology, University of Ulm Medical Center, Albert-Einstein-Allee 23, Ulm D-89081, Germany
| | - Renate B. Schnabel
- National Heart, Lung, and Blood Institute's and Boston University's Framingham Heart Study, 73 Mount Wayte Ave. Suite 2, Framingham, MA, USA
| | - Kenneth M. Rice
- Department of Biostatistics, University of Washington, Seattle, WA, USA
| | - Fernando Rivadeneira
- Department of Epidemiology, Erasmus University Medical Center, Rotterdam, The Netherlands
- Member of the Netherlands Consortium on Healthy Aging (NCHA), Leiden, The Netherlands
- Department of Internal Medicine, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Ron C. Hoogeveen
- Division of Atherosclerosis and Vascular Medicine, Department of Medicine, Baylor College of Medicine, Methodist DeBakey Heart and Vascular Center, 6565 Fannin, MS A-601, Houston, TX, USA
| | - João Daniel Fontes
- National Heart, Lung, and Blood Institute's and Boston University's Framingham Heart Study, 73 Mount Wayte Ave. Suite 2, Framingham, MA, USA
- Section of Preventive Medicine and Cardiology, Department of Medicine, Boston University School of Medicine, Boston, MA, USA
| | - Christa Meisinger
- Helmholtz Zentrum München, German Research Center for Environmental Health, Institute of Epidemiology, Neuherberg, Germany
| | - John F. Keaney
- Division of Cardiovascular Medicine, Department of Medicine, University of Massachusetts Medical School, Worcester, MA, USA
| | - Rozenn Lemaitre
- Cardiovascular Health Research Unit and Department of Medicine, University of Washington, Seattle, WA, USA
| | - Yurii S. Aulchenko
- Department of Epidemiology, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Ramachandran S. Vasan
- National Heart, Lung, and Blood Institute's and Boston University's Framingham Heart Study, 73 Mount Wayte Ave. Suite 2, Framingham, MA, USA
| | | | | | - Cornelia M. van Duijn
- Department of Epidemiology, Erasmus University Medical Center, Rotterdam, The Netherlands
- Member of the Netherlands Consortium on Healthy Aging (NCHA), Leiden, The Netherlands
| | - Jeanenne J. Nelson
- Worldwide Epidemiology, GlaxoSmithKline, Research Triangle Park, NC, USA
| | - Winfried März
- Synlab Center of Laboratory Diagnostics Heidelberg, Heidelberg, Germany
- Clinical Institute of Medical and Chemical Laboratory Diagnostics, Medical University of Graz, Graz, Austria
- Institute of Public Health, Social and Preventive Medicine, Medical Faculty Mannheim, University of Heidelberg, Heidelberg, Germany
| | | | - Ruth M. McPherson
- John & Jennifer Ruddy Canadian Cardiovascular Genetics Centre, University of Ottawa Heart Institute, Ottawa, Ontario, Canada
| | | | - Bruce M. Psaty
- Department of Epidemiology, University of Washington, Seattle, WA, USA
- Group Health Research Institute, Group Health Cooperative, Seattle, WA, USA
- Department of Medicine, University of Washington, Seattle, WA, USA
- Department of Health Services, University of Washington, Seattle, WA, USA
| | - Christian Gieger
- Helmholtz Zentrum München, German Research Center for Environmental Health, Institute of Epidemiology, Neuherberg, Germany
| | - David Siscovick
- Department of Epidemiology, University of Washington, Seattle, WA, USA
- Department of Medicine, University of Washington, Seattle, WA, USA
| | - Albert Hofman
- Department of Epidemiology, Erasmus University Medical Center, Rotterdam, The Netherlands
- Member of the Netherlands Consortium on Healthy Aging (NCHA), Leiden, The Netherlands
| | - Thomas Illig
- Helmholtz Zentrum München, German Research Center for Environmental Health, Institute of Epidemiology, Neuherberg, Germany
- Ludwig-Maximilians University Munich, Institute of Medical Data Management, Biometrics and Epidemiology, Chair of Epidemiology, Munich, Germany
| | - Mary Cushman
- Department of Medicine, University of Vermont, Burlington, VT, USA
| | - Jennifer F. Yamamoto
- National Heart, Lung, and Blood Institute's and Boston University's Framingham Heart Study, 73 Mount Wayte Ave. Suite 2, Framingham, MA, USA
| | - Jerome I. Rotter
- Medical Genetics Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Martin G. Larson
- National Heart, Lung, and Blood Institute's and Boston University's Framingham Heart Study, 73 Mount Wayte Ave. Suite 2, Framingham, MA, USA
| | - Alexandre F.R. Stewart
- John & Jennifer Ruddy Canadian Cardiovascular Genetics Centre, University of Ottawa Heart Institute, Ottawa, Ontario, Canada
| | - Eric Boerwinkle
- Human Genetics Center, University of Texas Health Science Center at Houston, Houston, TX, USA
| | - Jacqueline C.M. Witteman
- Department of Epidemiology, Erasmus University Medical Center, Rotterdam, The Netherlands
- Member of the Netherlands Consortium on Healthy Aging (NCHA), Leiden, The Netherlands
| | - Russell P. Tracy
- Department of Pathology, University of Vermont College of Medicine, Burlington, VT, USA
- Department of Biochemistry, University of Vermont College of Medicine, Burlington, VT, USA
| | - Wolfgang Koenig
- Department of Internal Medicine II–Cardiology, University of Ulm Medical Center, Albert-Einstein-Allee 23, Ulm D-89081, Germany
| | - Emelia J. Benjamin
- National Heart, Lung, and Blood Institute's and Boston University's Framingham Heart Study, 73 Mount Wayte Ave. Suite 2, Framingham, MA, USA
- Section of Preventive Medicine and Cardiology, Department of Medicine, Boston University School of Medicine, Boston, MA, USA
| | - Christie M. Ballantyne
- Division of Atherosclerosis and Vascular Medicine, Department of Medicine, Baylor College of Medicine, Methodist DeBakey Heart and Vascular Center, 6565 Fannin, MS A-601, Houston, TX, USA
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Dennis EA, Cao J, Hsu YH, Magrioti V, Kokotos G. Phospholipase A2 enzymes: physical structure, biological function, disease implication, chemical inhibition, and therapeutic intervention. Chem Rev 2011; 111:6130-85. [PMID: 21910409 PMCID: PMC3196595 DOI: 10.1021/cr200085w] [Citation(s) in RCA: 804] [Impact Index Per Article: 61.8] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Edward A. Dennis
- Department of Chemistry and Biochemistry and Pharmacology, School of Medicine, University of California, San Diego, La Jolla, California 92093-0601
| | - Jian Cao
- Department of Chemistry and Biochemistry and Pharmacology, School of Medicine, University of California, San Diego, La Jolla, California 92093-0601
| | - Yuan-Hao Hsu
- Department of Chemistry and Biochemistry and Pharmacology, School of Medicine, University of California, San Diego, La Jolla, California 92093-0601
| | - Victoria Magrioti
- Laboratory of Organic Chemistry, Department of Chemistry, University of Athens, Panepistimiopolis, Athens 15771, Greece
| | - George Kokotos
- Laboratory of Organic Chemistry, Department of Chemistry, University of Athens, Panepistimiopolis, Athens 15771, Greece
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Cao J, Hsu YH, Li S, Woods VL, Dennis EA. Lipoprotein-associated phospholipase A(2) interacts with phospholipid vesicles via a surface-disposed hydrophobic α-helix. Biochemistry 2011; 50:5314-21. [PMID: 21553808 DOI: 10.1021/bi101916w] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Lipoprotein-associated phospholipase A(2) (Lp-PLA(2)) plays important roles in both the inhibition and promotion of inflammation in human disease. It catalyzes the hydrolytic inactivation of plasma platelet activating factor (PAF) and is also known as PAF acetylhydrolase. High levels of PAF are implicated in a variety of inflammatory diseases such as asthma, necrotizing enterocolitis, and sepsis. Lp-PLA(2) also associates with lipoproteins in human plasma where it hydrolyzes oxidized phospholipids to produce pro-inflammatory lipid mediators that can promote inflammation and the development of atherosclerosis. Lp-PLA(2) plasma levels have recently been identified as a biomarker of vascular inflammation, atherosclerotic vulnerability, and future cardiovascular events. The enzyme is thus a prominent target for the development of inflammation and atherosclerosis-modulating therapeutics. While the crystallographically determined structure of the enzyme is known, the enzyme's mechanism of interaction with PAF and the function-modulating lipids in lipoproteins is unknown. We have employed peptide amide hydrogen-deuterium exchange mass spectrometry (DXMS) to characterize the association of Lp-PLA(2) with dimyristoylphosphatidylcholine (DMPC) vesicles and found that specific residues 113-120 in one of the enzyme's surface-disposed hydrophobic α-helices likely mediate liposome binding.
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Affiliation(s)
- Jian Cao
- Department of Chemistry and Biochemistry and Pharmacology, University of California, La Jolla, CA 92093-0601, USA
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White H, Held C, Stewart R, Watson D, Harrington R, Budaj A, Steg PG, Cannon CP, Krug-Gourley S, Wittes J, Trivedi T, Tarka E, Wallentin L. Study design and rationale for the clinical outcomes of the STABILITY Trial (STabilization of Atherosclerotic plaque By Initiation of darapLadIb TherapY) comparing darapladib versus placebo in patients with coronary heart disease. Am Heart J 2010; 160:655-61. [PMID: 20934559 DOI: 10.1016/j.ahj.2010.07.006] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/13/2010] [Accepted: 07/06/2010] [Indexed: 11/28/2022]
Abstract
BACKGROUND Elevated plasma levels of lipoprotein-associated phospholipase A(2) (Lp-PLA(2)) are associated with increased risk of cardiovascular (CV) events. Direct inhibition of this proinflammatory enzyme with darapladib may benefit CV patients when given as an adjunct to standard of care, including lipid-lowering and antiplatelet therapies. METHODS STABILITY is a randomized, placebo-controlled, double-blind, international, multicenter, event-driven trial. The study has randomized 15,828 patients with chronic coronary heart disease (CHD) receiving standard of care to darapladib enteric-coated (EC) tablets, 160 mg or placebo. RESULTS The primary end point is the composite of major adverse cardiovascular events (MACE): CV death, nonfatal myocardial infarction, and nonfatal stroke. The key secondary end points will include major coronary events, total coronary events, individual components of MACE, and all-cause mortality. Prespecified substudies include 24-hour ambulatory blood pressure monitoring, albuminuria progression, changes in cognitive function, and pharmacokinetic and biomarker analyses. Health economic outcomes and characterization of baseline lifestyle risk factors also will be assessed. The study will continue until 1,500 primary end points have occurred to achieve 90% power to detect a 15.5% reduction in the primary end point. The median treatment duration is anticipated to be 2.75 years. CONCLUSIONS STABILITY will assess whether direct inhibition of Lp-PLA(2) with darapladib added to the standard of care confers clinical benefit to patients with CHD.
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Affiliation(s)
- Harvey White
- Green Lane Cardiovascular Service, Auckland City Hospital, Auckland, New Zealand.
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Novel mechanism for regulation of plasma platelet-activating factor acetylhydrolase expression in mammalian cells. Biochem J 2010; 428:269-79. [DOI: 10.1042/bj20100039] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The plasma form of PAF-AH [PAF (platelet-activating factor) acetylhydrolase; also known as LpPLA2 (lipopoprotein-associated phospholipase A2), PLA2G7] catalyses the release of sn-2 fatty acyl residues from PAF, oxidatively fragmented phospholipids, and esterified isoprostanes. The plasma levels of this enzyme vary widely among mammalian species, including mice and humans, but the mechanisms that account for these differences are largely unknown. We investigated the basis for these variations using molecular and biochemical approaches. We identified an N-terminal domain that played key roles in the determination of steady-state expression levels. The mouse N-terminal domain robustly enhanced protein expression levels, possibly owing to its ability to adopt a globular conformation that is absent in the human protein. We investigated the mechanism(s) whereby the N-terminal stretch modulated PAF-AH levels and found that differential expression was not due to variations in the efficiency of transcription, translation, or mRNA stability. Studies designed to evaluate the ability of precursor forms of PAF-AH to mature to fully active proteins indicated that the N-terminal end of human and mouse PAF-AH played important and opposite roles in this process. These domains also modulated the levels of expression of an unrelated polypeptide by affecting the stability of precursor forms of the protein. These studies provide insights that contribute to our understanding of the molecular features and mechanisms that contribute to differential expression of plasma PAF-AH in mammals.
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Srinivasan P, Bahnson BJ. Molecular Model of Plasma PAF Acetylhydrolase-Lipoprotein Association: Insights from the Structure. Pharmaceuticals (Basel) 2010; 3:541-557. [PMID: 27713267 PMCID: PMC4033968 DOI: 10.3390/ph3030541] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2010] [Revised: 02/07/2010] [Accepted: 03/05/2010] [Indexed: 11/18/2022] Open
Abstract
Plasma platelet-activating factor acetylhydrolase (PAF-AH), also called lipoprotein-associated phospholipase A2 (Lp-PLA2), is a group VIIA PLA2 enzyme that catalyzes the hydrolysis of PAF and certain oxidized phospholipids. Although the role of PAF-AH as a pro- or anti-atherosclerotic enzyme is highly debated, several studies have shown it to be an independent marker of cardiovascular diseases. In humans the majority of plasma PAF-AH is bound to LDL and a smaller portion to HDL; the majority of the enzyme being associated with small dense LDL and VHDL-1 subclasses. Several studies suggest that the anti- or pro-atherosclerotic tendency of PAF-AH might be dependent on the type of lipoprotein it is associated with. Amino acid residues in PAF-AH necessary for binding to LDL and HDL have been identified. However our understanding of the interaction of PAF-AH with LDL and HDL is still incomplete. In this review we present an overview of what is already known about the interaction of PAF-AH with lipoprotein particles, and we pose questions that are yet to be answered. The recently solved crystal structure of PAF-AH, along with functional work done by others is used as a guide to develop a model of interaction of PAF-AH with lipoprotein particles.
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Affiliation(s)
| | - Brian J Bahnson
- Department of Chemistry & Biochemistry, University of Delaware, Newark, DE, 19716, USA.
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