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Ali O, Szabó A. Review of Eukaryote Cellular Membrane Lipid Composition, with Special Attention to the Fatty Acids. Int J Mol Sci 2023; 24:15693. [PMID: 37958678 PMCID: PMC10649022 DOI: 10.3390/ijms242115693] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Revised: 10/24/2023] [Accepted: 10/25/2023] [Indexed: 11/15/2023] Open
Abstract
Biological membranes, primarily composed of lipids, envelop each living cell. The intricate composition and organization of membrane lipids, including the variety of fatty acids they encompass, serve a dynamic role in sustaining cellular structural integrity and functionality. Typically, modifications in lipid composition coincide with consequential alterations in universally significant signaling pathways. Exploring the various fatty acids, which serve as the foundational building blocks of membrane lipids, provides crucial insights into the underlying mechanisms governing a myriad of cellular processes, such as membrane fluidity, protein trafficking, signal transduction, intercellular communication, and the etiology of certain metabolic disorders. Furthermore, comprehending how alterations in the lipid composition, especially concerning the fatty acid profile, either contribute to or prevent the onset of pathological conditions stands as a compelling area of research. Hence, this review aims to meticulously introduce the intricacies of membrane lipids and their constituent fatty acids in a healthy organism, thereby illuminating their remarkable diversity and profound influence on cellular function. Furthermore, this review aspires to highlight some potential therapeutic targets for various pathological conditions that may be ameliorated through dietary fatty acid supplements. The initial section of this review expounds on the eukaryotic biomembranes and their complex lipids. Subsequent sections provide insights into the synthesis, membrane incorporation, and distribution of fatty acids across various fractions of membrane lipids. The last section highlights the functional significance of membrane-associated fatty acids and their innate capacity to shape the various cellular physiological responses.
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Affiliation(s)
- Omeralfaroug Ali
- Agrobiotechnology and Precision Breeding for Food Security National Laboratory, Institute of Physiology and Animal Nutrition, Department of Animal Physiology and Health, Hungarian University of Agriculture and Life Sciences, Guba Sándor Str. 40, 7400 Kaposvár, Hungary;
| | - András Szabó
- Agrobiotechnology and Precision Breeding for Food Security National Laboratory, Institute of Physiology and Animal Nutrition, Department of Animal Physiology and Health, Hungarian University of Agriculture and Life Sciences, Guba Sándor Str. 40, 7400 Kaposvár, Hungary;
- HUN-REN-MATE Mycotoxins in the Food Chain Research Group, Hungarian University of Agriculture and Life Sciences, Guba Sándor Str. 40, 7400 Kaposvár, Hungary
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Nordin N, Jalil J, Ghani MFA, Abdullah AA, Othman R. Molecular Modelling Simulations and Inhibitory Effects of Naturally Derived Flavonoids Targeting Platelet-Activating Factor Receptor (PAFR). LETT DRUG DES DISCOV 2022. [DOI: 10.2174/1570180818666210614170322] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Background:
Platelet-activating factor (PAF) is an agonist mediator in the inflammatory
process, which interacts with PAF receptor (PAFR) that eventually causes cancers, respiratory and
neurodegenerative diseases. This interaction activates the mitogen-activated protein kinase (MAPK)
pathway, leading to a pro-inflammatory cascade. The pathophysiological conditions due to activation
of inflammatory cascade could be inhibited by PAF antagonists.
Objectives:
In this study, selected naturally derived flavonoids (flavone, biochanin A, and myricetin)
with different functional groups were subjected to molecular modelling and experimental studies to
investigate their potential as PAF antagonists.
Method:
Interactions of flavonoids and PAF were assessed via Autodock Vina for molecular docking
and the AMBER program for molecular dynamic simulations. The experimentally antagonistic effects
of the flavonoids were also conducted via PAF inhibitory assay to determine the IC50 values.
Results:
The findings of docking and dynamic simulations have revealed that all selected flavonoids
interact with PAFR in the binding site with considerably good binding affinity up to - 9.8 kcal mol-1 as
compared to cedrol (- 8.1 kcal mol-1) as a standard natural PAFR antagonist. The PAFR-flavonoid
complexes exhibited four conserved active site residues, which included W73, F97, F174, and L279.
The stability of all complexes was attained in a 30 ns simulation. The findings of in silico analyses
were then compared to the experimental study on PAF inhibitory assay. Inhibitory effects of flavonoids
against PAFR showed moderate activities, ranging from 27.8 – 30.8 μgM-1.
Conclusion:
All studied flavonoids could act as promising PAF antagonists with some enhancement in
their structures to exhibit potent antagonistic activity. However, these naturally derived flavonoids
demand further investigation at cellular and animal models to develop new PAF antagonist drug candidates
for treating PAF-mediated diseases.
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Affiliation(s)
- Noraziah Nordin
- Department of Basic Medical Sciences 1, Faculty of Medicine & Health Sciences, Universiti Sains Islam Malaysia,
71800, Nilai, Negeri Sembilan Malaysia
| | - Juriyati Jalil
- Drug and Herbal Research Centre, Faculty of Pharmacy, Universiti Kebangsaan
Malaysia, 50300, Kuala Lumpur, Malaysia
| | - Mohd Faiz Abd Ghani
- Department of Basic Medical Sciences 1, Faculty of Medicine & Health Sciences, Universiti Sains Islam Malaysia,
71800, Nilai, Negeri Sembilan Malaysia
| | - Adib Afandi Abdullah
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy,
University Malaya, 50603, Kuala Lumpur, Malaysia
| | - Rozana Othman
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy,
University Malaya, 50603, Kuala Lumpur, Malaysia
- Centre for Natural Product Research and Drug Discovery
(CENAR), University Malaya, 50603, Kuala Lumpur, Malaysia
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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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Yi L, Zhang J, Zhong J, Zheng Y. Elevated Levels of Platelet Activating Factor and Its Acetylhydrolase Indicate High Risk of Kawasaki Disease. J Interferon Cytokine Res 2020; 40:159-167. [PMID: 31841639 DOI: 10.1089/jir.2019.0141] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Affiliation(s)
- Lunyu Yi
- Ministry of Education Key Laboratory of Child Development and Disorders, National Clinical Research Center for Child Health and Disorders, China International Science and Technology Cooperation Base of Child Development and Critical Disorders, Children's Hospital of Chongqing Medical University, Chongqing Key Laboratory of Pediatrics, Chongqing, P. R. China
| | - Jing Zhang
- Department of Pediatrics, China Japan Friendship Hospital, Beijing, P. R. China
| | - Jiarong Zhong
- Ministry of Education Key Laboratory of Child Development and Disorders, National Clinical Research Center for Child Health and Disorders, China International Science and Technology Cooperation Base of Child Development and Critical Disorders, Children's Hospital of Chongqing Medical University, Chongqing Key Laboratory of Pediatrics, Chongqing, P. R. China
| | - Yuqiang Zheng
- Ministry of Education Key Laboratory of Child Development and Disorders, National Clinical Research Center for Child Health and Disorders, China International Science and Technology Cooperation Base of Child Development and Critical Disorders, Children's Hospital of Chongqing Medical University, Chongqing Key Laboratory of Pediatrics, Chongqing, P. R. China
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Chaithra VH, Jacob SP, Lakshmikanth CL, Sumanth MS, Abhilasha KV, Chen CH, Thyagarajan A, Sahu RP, Travers JB, McIntyre TM, Kemparaju K, Marathe GK. Modulation of inflammatory platelet-activating factor (PAF) receptor by the acyl analogue of PAF. J Lipid Res 2018; 59:2063-2074. [PMID: 30139761 DOI: 10.1194/jlr.m085704] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2018] [Revised: 08/20/2018] [Indexed: 11/20/2022] Open
Abstract
Platelet-activating factor (PAF) is a potent inflammatory mediator that exerts its actions via the single PAF receptor (PAF-R). Cells that biosynthesize alkyl-PAF also make abundant amounts of the less potent PAF analogue acyl-PAF, which competes for PAF-R. Both PAF species are degraded by the plasma form of PAF acetylhydrolase (PAF-AH). We examined whether cogenerated acyl-PAF protects alkyl-PAF from systemic degradation by acting as a sacrificial substrate to enhance inflammatory stimulation or as an inhibitor to dampen PAF-R signaling. In ex vivo experiments both PAF species are prothrombotic in isolation, but acyl-PAF reduced the alkyl-PAF-induced stimulation of human platelets that express canonical PAF-R. In Swiss albino mice, alkyl-PAF causes sudden death, but this effect can also be suppressed by simultaneously administering boluses of acyl-PAF. When PAF-AH levels were incrementally elevated, the protective effect of acyl-PAF on alkyl-PAF-induced death was serially decreased. We conclude that, although acyl-PAF in isolation is mildly proinflammatory, in a pathophysiological setting abundant acyl-PAF suppresses the action of alkyl-PAF. These studies provide evidence for a previously unrecognized role for acyl-PAF as an inflammatory set-point modulator that regulates both PAF-R signaling and hydrolysis.
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Affiliation(s)
| | - Shancy Petsel Jacob
- Department of Studies in Biochemistry University of Mysore, Manasagangothri, Mysuru 570006, India
| | | | - Mosale Seetharam Sumanth
- Department of Studies in Biochemistry University of Mysore, Manasagangothri, Mysuru 570006, India
| | | | - Chu-Huang Chen
- Vascular and Medicinal Research, Texas Heart Institute, Houston, TX 77030
| | - Anita Thyagarajan
- Department of Pharmacology and Toxicology, Boonshoft School of Medicine, Wright State University, Dayton, OH 45435
| | - Ravi P Sahu
- Department of Pharmacology and Toxicology, Boonshoft School of Medicine, Wright State University, Dayton, OH 45435
| | - Jeffery Bryant Travers
- Department of Pharmacology and Toxicology, Boonshoft School of Medicine, Wright State University, Dayton, OH 45435
| | - Thomas M McIntyre
- Department of Cellular and Molecular Medicine, Cleveland Clinic Lerner Research Institute, Cleveland, OH
| | - Kempaiah Kemparaju
- Department of Studies in Biochemistry University of Mysore, Manasagangothri, Mysuru 570006, India
| | - Gopal Kedihithlu Marathe
- Department of Studies in Biochemistry University of Mysore, Manasagangothri, Mysuru 570006, India .,and Department of Studies in Molecular Biology, University of Mysore, Manasagangothri, Mysuru 570006, India
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Noh KT, Jung ID, Cha GS, Han MK, Park YM. Platelet-activating Factor Mediates Endotoxin Tolerance by Regulating Indoleamine 2,3-Dioxygenase-dependent Expression of the Suppressor of Cytokine Signaling 3. J Biol Chem 2017; 292:3290-3298. [PMID: 28077574 DOI: 10.1074/jbc.m116.764464] [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] [Received: 11/06/2016] [Revised: 12/25/2016] [Indexed: 11/06/2022] Open
Abstract
Indoleamine 2,3-dioxygenase (IDO) mediates immune tolerance, and suppressor of cytokine signaling 3 (SOCS3) negatively regulates the JAK/STAT signal transduction pathway. We determined previously that platelet-activating factor (PAF) protects mice against LPS-induced endotoxic shock, but its detailed mechanism of action was unknown. We performed survival experiments in IDO+/+ and IDO-/- mice using an LPS-induced endotoxemia model and rated organ injury (neutrophil infiltration and liver function). Using ELISA and Western blotting, we also investigated the mechanism of PAF-mediated endotoxin tolerance during endotoxemia. PAF-mediated endotoxin tolerance was dependent on IDO in vivo and in vitro and was not observed in IDO-/- mice. JAK/STAT signaling, crucial for SOCS3 expression, was also impaired in the absence of IDO. In an IDO- and STAT-dependent manner, PAF mediated a decrease in IL-12 and a dramatic increase in IL-10 and reduced mouse mortality. In addition, PAF attenuated LPS-mediated neutrophil infiltration into the lungs and interactions between neutrophil-like (THP-1) and endothelial cells (human umbilical vein endothelial cells). These results indicate that PAF-mediated endotoxin tolerance is initiated via IDO- and JAK/STAT-dependent expression of SOCS3. Our study has revealed a novel tolerogenic mechanism of IDO action and an important association between IDO and SOCS3 with respect to endotoxin tolerance.
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Affiliation(s)
- Kyung Tae Noh
- Department of Infectious Diseases, Armed Forces Medical Research Institute, 90bun, Jaunro, Yuseong-gu, Daejeon 305-878, South Korea
| | - In Duk Jung
- Department of Immunology, College of Medicine, Konkuk University, Seoul 143-701, South Korea
| | - Gil Sun Cha
- Department of Immunology, College of Medicine, Konkuk University, Seoul 143-701, South Korea
| | - Myung-Kwan Han
- Department of Microbiology, Chonbuk National University Medical School, Jeonju 561-182, South Korea.
| | - Yeong-Min Park
- Department of Immunology, College of Medicine, Konkuk University, Seoul 143-701, South Korea.
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Palur Ramakrishnan AVK, Varghese TP, Vanapalli S, Nair NK, Mingate MD. Platelet activating factor: A potential biomarker in acute coronary syndrome? Cardiovasc Ther 2016; 35:64-70. [DOI: 10.1111/1755-5922.12233] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/04/2016] [Revised: 10/07/2016] [Accepted: 10/25/2016] [Indexed: 11/28/2022] Open
Affiliation(s)
| | - Treesa P. Varghese
- Department of Pharmacy Practice; JSS College of Pharmacy (Jagadguru Sri Shivarathreeswara University, Mysore); Udhagamandalam Tamil Nadu India
| | - Sreedevi Vanapalli
- Department of Pharmacy Practice; JSS College of Pharmacy (Jagadguru Sri Shivarathreeswara University, Mysore); Udhagamandalam Tamil Nadu India
| | - Narayanan K. Nair
- Department of Pharmacy Practice; JSS College of Pharmacy (Jagadguru Sri Shivarathreeswara University, Mysore); Udhagamandalam Tamil Nadu India
| | - Menge Denis Mingate
- Department of Pharmacy Practice; JSS College of Pharmacy (Jagadguru Sri Shivarathreeswara University, Mysore); Udhagamandalam Tamil Nadu India
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9
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Bhosle VK, Rivera JC, Zhou TE, Omri S, Sanchez M, Hamel D, Zhu T, Rouget R, Rabea AA, Hou X, Lahaie I, Ribeiro-da-Silva A, Chemtob S. Nuclear localization of platelet-activating factor receptor controls retinal neovascularization. Cell Discov 2016; 2:16017. [PMID: 27462464 PMCID: PMC4941644 DOI: 10.1038/celldisc.2016.17] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2016] [Accepted: 05/11/2016] [Indexed: 02/08/2023] Open
Abstract
Platelet-activating factor (PAF) is a pleiotropic phospholipid with proinflammatory, procoagulant and angiogenic actions on the vasculature. We and others have reported the presence of PAF receptor (Ptafr) at intracellular sites such as the nucleus. However, mechanisms of localization and physiologic functions of intracellular Ptafr remain poorly understood. We hereby identify the importance of C-terminal motif of the receptor and uncover novel roles of Rab11a GTPase and importin-5 in nuclear translocation of Ptafr in primary human retinal microvascular endothelial cells. Nuclear localization of Ptafr is independent of exogenous PAF stimulation as well as intracellular PAF biosynthesis. Moreover, nuclear Ptafr is responsible for the upregulation of unique set of growth factors, including vascular endothelial growth factor, in vitro and ex vivo. We further corroborate the intracrine PAF signaling, resulting in angiogenesis in vivo, using Ptafr antagonists with distinct plasma membrane permeability. Collectively, our findings show that nuclear Ptafr translocates in an agonist-independent manner, and distinctive functions of Ptafr based on its cellular localization point to another dimension needed for pharmacologic selectivity of drugs.
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Affiliation(s)
- Vikrant K Bhosle
- Department of Pharmacology and Therapeutics, McGill University, Montréal, QC, Canada; CHU Sainte Justine Hospital Research Centre, University of Montréal, Montréal, QC, Canada; Department of Ophthalmology, Research Centre of Hôpital Maisonneuve-Rosemont, University of Montréal, Montréal, QC, Canada
| | - José Carlos Rivera
- CHU Sainte Justine Hospital Research Centre, University of Montréal, Montréal, QC, Canada; Department of Ophthalmology, Research Centre of Hôpital Maisonneuve-Rosemont, University of Montréal, Montréal, QC, Canada
| | - Tianwei Ellen Zhou
- Department of Pharmacology and Therapeutics, McGill University, Montréal, QC, Canada; CHU Sainte Justine Hospital Research Centre, University of Montréal, Montréal, QC, Canada; Department of Ophthalmology, Research Centre of Hôpital Maisonneuve-Rosemont, University of Montréal, Montréal, QC, Canada; Department of Medicine, McGill University Health Center, Montreal, QC, Canada
| | - Samy Omri
- CHU Sainte Justine Hospital Research Centre, University of Montréal, Montréal, QC, Canada; Department of Ophthalmology, Research Centre of Hôpital Maisonneuve-Rosemont, University of Montréal, Montréal, QC, Canada
| | - Melanie Sanchez
- Department of Pharmacology and Therapeutics, McGill University, Montréal, QC, Canada; CHU Sainte Justine Hospital Research Centre, University of Montréal, Montréal, QC, Canada; Department of Ophthalmology, Research Centre of Hôpital Maisonneuve-Rosemont, University of Montréal, Montréal, QC, Canada
| | - David Hamel
- CHU Sainte Justine Hospital Research Centre, University of Montréal, Montréal, QC, Canada; Department of Pharmacology, University of Montréal, Montréal, QC, Canada
| | - Tang Zhu
- CHU Sainte Justine Hospital Research Centre, University of Montréal , Montréal, QC, Canada
| | - Raphael Rouget
- Department of Pharmacology and Therapeutics, McGill University, Montréal, QC, Canada; CHU Sainte Justine Hospital Research Centre, University of Montréal, Montréal, QC, Canada
| | - Areej Al Rabea
- Experimental Surgery, Montreal General Hospital, McGill University , Montréal, QC, Canada
| | - Xin Hou
- CHU Sainte Justine Hospital Research Centre, University of Montréal , Montréal, QC, Canada
| | - Isabelle Lahaie
- CHU Sainte Justine Hospital Research Centre, University of Montréal, Montréal, QC, Canada; Department of Ophthalmology, Research Centre of Hôpital Maisonneuve-Rosemont, University of Montréal, Montréal, QC, Canada
| | - Alfredo Ribeiro-da-Silva
- Department of Pharmacology and Therapeutics, McGill University, Montréal, QC, Canada; Alan Edwards Centre for Research on Pain, McGill University, Montréal, QC, Canada; Department of Anatomy and Cell Biology, McGill University, Montréal, QC, Canada
| | - Sylvain Chemtob
- Department of Pharmacology and Therapeutics, McGill University, Montréal, QC, Canada; CHU Sainte Justine Hospital Research Centre, University of Montréal, Montréal, QC, Canada; Department of Ophthalmology, Research Centre of Hôpital Maisonneuve-Rosemont, University of Montréal, Montréal, QC, Canada; Department of Pharmacology, University of Montréal, Montréal, QC, Canada; Departments of Pediatrics and Ophthalmology, Faculty of Medicine, University of Montréal, Montréal, QC, Canada
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Platelets in the immune response: Revisiting platelet-activating factor in anaphylaxis. J Allergy Clin Immunol 2015; 135:1424-32. [PMID: 26051949 DOI: 10.1016/j.jaci.2015.04.019] [Citation(s) in RCA: 79] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2015] [Revised: 04/21/2015] [Accepted: 04/21/2015] [Indexed: 01/09/2023]
Abstract
Anaphylaxis is an acute, severe, life-threatening multisystem allergic reaction resulting from the sudden systemic release of biochemical mediators and chemotactic substances. Release of both preformed granule-associated mediators and newly generated lipid-derived mediators contributes to the amplification and prolongation of anaphylaxis. Platelet-activating factor (PAF) is a potent phospholipid-derived mediator the central role of which has been well established in experimental models of both immune-mediated and non-immune mediated anaphylaxis. It is produced and secreted by several types of cells, including mast cells, monocytes, tissue macrophages, platelets, eosinophils, endothelial cells, and neutrophils. PAF is implicated in platelet aggregation and activation through release of vasoactive amines in the inflammatory response, resulting in increased vascular permeability, circulatory collapse, decreased cardiac output, and various other biological effects. PAF is rapidly hydrolyzed and degraded to an inactive metabolite, lysoPAF, by the enzyme PAF acetylhydrolase, the activity of which has shown to correlate inversely with PAF levels and predispose to severe anaphylaxis. In addition to its role in anaphylaxis, PAF has also been implicated as a mediator in both allergic and nonallergic inflammatory diseases, including allergic rhinitis, sepsis, atherosclerotic disease, and malignancy, in which PAF signaling has an established role. The therapeutic role of PAF antagonism has been investigated for several diseases, with variable results thus far. Further investigation of its role in pathology and therapeutic modulation is highly anticipated because of the pressing need for more selective and targeted therapy for the management of severe anaphylaxis.
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Mitchell MJ, Lin KS, King MR. Fluid shear stress increases neutrophil activation via platelet-activating factor. Biophys J 2014; 106:2243-53. [PMID: 24853753 PMCID: PMC4052238 DOI: 10.1016/j.bpj.2014.04.001] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2013] [Revised: 03/20/2014] [Accepted: 04/01/2014] [Indexed: 12/11/2022] Open
Abstract
Leukocyte exposure to hemodynamic shear forces is critical for physiological functions including initial adhesion to the endothelium, the formation of pseudopods, and migration into tissues. G-protein coupled receptors on neutrophils, which bind to chemoattractants and play a role in neutrophil chemotaxis, have been implicated as fluid shear stress sensors that control neutrophil activation. Recently, exposure to physiological fluid shear stresses observed in the microvasculature was shown to reduce neutrophil activation in the presence of the chemoattractant formyl-methionyl-leucyl-phenylalanine. Here, however, human neutrophil preexposure to uniform shear stress (0.1-2.75 dyn/cm(2)) in a cone-and-plate viscometer for 1-120 min was shown to increase, rather than decrease, neutrophil activation in the presence of platelet activating factor (PAF). Fluid shear stress exposure increased PAF-induced neutrophil activation in terms of L-selectin shedding, αMβ2 integrin activation, and morphological changes. Neutrophil activation via PAF was found to correlate with fluid shear stress exposure, as neutrophil activation increased in a shear stress magnitude- and time-dependent manner. These results indicate that fluid shear stress exposure increases neutrophil activation by PAF, and, taken together with previous observations, differentially controls how neutrophils respond to chemoattractants.
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Affiliation(s)
- Michael J Mitchell
- Department of Biomedical Engineering, Cornell University, Ithaca, New York
| | - Kimberly S Lin
- Department of Biomedical Engineering, Cornell University, Ithaca, New York
| | - Michael R King
- Department of Biomedical Engineering, Cornell University, Ithaca, New York.
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Abstract
Accurately diagnosing a patient with a possible food allergy is important to avoid unnecessary dietary restrictions and prevent life-threatening reactions. Routine testing modalities have limited accuracy, and an oral food challenge is often required to make a definitive diagnosis. Given that they are labor intensive and risk inducing an allergic reaction, several alternative diagnostic modalities have been investigated. Testing for IgE antibodies to particular protein components in foods has shown promise to improve diagnostics and has entered clinical practice. Additional modalities show potential, including epitope binding, T-cell studies, and basophil activation.
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Affiliation(s)
- Jacob D Kattan
- Department of Pediatric Allergy and Immunology, Jaffe Food Allergy Institute, Icahn School of Medicine at Mount Sinai, 1 Gustave L. Levy Place, Box 1198, New York, NY 10029, USA.
| | - Scott H Sicherer
- Department of Pediatric Allergy and Immunology, Jaffe Food Allergy Institute, Icahn School of Medicine at Mount Sinai, 1 Gustave L. Levy Place, Box 1198, New York, NY 10029, USA
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13
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Perelman B, Adil A, Vadas P. Relationship between platelet activating factor acetylhydrolase activity and apolipoprotein B levels in patients with peanut allergy. Allergy Asthma Clin Immunol 2014; 10:20. [PMID: 24808915 PMCID: PMC4012516 DOI: 10.1186/1710-1492-10-20] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2014] [Accepted: 03/31/2014] [Indexed: 11/10/2022] Open
Abstract
Background Platelet-activating factor (PAF) is a highly potent phospholipid mediator responsible for the life-threatening manifestations of anaphylaxis. PAF acetylhydrolase (PAF-AH) inactivates PAF and protects against severe anaphylaxis whereas deficiency of PAF-AH predisposes to severe or fatal anaphylaxis. Determinants of PAF-AH activity have not been studied in patients with peanut allergy. Objectives To determine whether plasma PAF-AH activity in patients with peanut allergy is related to formation of circulating complexes with apolipoprotein B (apoB) the main surface protein on low density lipoprotein particles. Methods Plasma PAF-AH activity and apoB concentrations were measured in 63 peanut allergic patients (35 boys, 28 girls, ages 2 – 19 years). ApoB concentration was measured immunoturbidimetrically using goat anti-human apoB. The correlation between PAF-AH activity and apoB concentration was determined. Results A positive correlation was found between PAF-AH activity and apoB concentration (r2 = 0.59, P < 0.0001). Conclusion In peanut allergic patients, PAF-AH activity strongly correlates with apoB concentration, suggesting the presence of circulating PAF-AH- lipoprotein complexes.
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Affiliation(s)
- Boris Perelman
- Division of Allergy and Clinical Immunology, Department of Medicine, St. Michael's Hospital, University of Toronto, 30 Bond St., M5B 1 W8 Toronto, ON, Canada
| | - Areej Adil
- Division of Allergy and Clinical Immunology, Department of Medicine, St. Michael's Hospital, University of Toronto, 30 Bond St., M5B 1 W8 Toronto, ON, Canada
| | - Peter Vadas
- Division of Allergy and Clinical Immunology, Department of Medicine, St. Michael's Hospital, University of Toronto, 30 Bond St., M5B 1 W8 Toronto, ON, Canada
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Teixeira-da-Cunha MGA, Gomes RN, Roehrs N, Bozza FA, Prescott SM, Stafforini D, Zimmerman GA, Bozza PT, Castro-Faria-Neto HC. Bacterial clearance is improved in septic mice by platelet-activating factor-acetylhydrolase (PAF-AH) administration. PLoS One 2013; 8:e74567. [PMID: 24069320 PMCID: PMC3771912 DOI: 10.1371/journal.pone.0074567] [Citation(s) in RCA: 22] [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: 12/30/2012] [Accepted: 08/05/2013] [Indexed: 11/18/2022] Open
Abstract
Current evidence indicates that dysregulation of the host inflammatory response to infectious agents is central to the mortality of patients with sepsis. Strategies to block inflammatory mediators such as PAF have been investigated as adjuvant therapies for sepsis. PAF-AH, the enzyme responsible for PAF degradation, showed positive results in pre-clinical studies and phase II clinical trials, but the results of a phase III study were disappointing. In this study, we investigated the potential protective mechanism of PAF-AH in sepsis using the murine model of cecal ligation and puncture (CLP). Treatment with rPAF-AH increased peritoneal fluid levels of the anti-inflammatory mediators MCP-1/CCL2 after CLP. The numbers of bacteria (CFU) in the peritoneal cavity were decreased in the rPAF-AH-treated group, indicating more efficient bacterial clearance after rPAF-AH treatment. Interestingly, we observed increased levels of nitric oxide (NO) after PAF-AH administration, and rPAF-AH treatment did not decrease CFU numbers either in iNOS-deficient mice or in CCR2-deficient mice. We concluded that administration of exogenous rPAF-AH reduced inflammatory injury, altered cytokine levels and favored bacterial clearance with a clear impact on mortality through modulation of MCP-1/CCL2 and NO levels in a clinically relevant sepsis model.
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Affiliation(s)
| | - Rachel N. Gomes
- Laboratório De Imunofarmacologia, Instituto Oswaldo Cruz, Fiocruz, RJ, Brazil
- Laboratório de Investigação em Medicina Intensiva, IPEC, Fiocruz, RJ, Brazil
- * E-mail:
| | - Nathassia Roehrs
- Laboratório De Imunofarmacologia, Instituto Oswaldo Cruz, Fiocruz, RJ, Brazil
| | - Fernando A. Bozza
- Laboratório de Investigação em Medicina Intensiva, IPEC, Fiocruz, RJ, Brazil
| | - Stephen M. Prescott
- Oklahoma Medical Research Foundation, Oklahoma City, United States of America
| | - Diana Stafforini
- Huntsman Cancer Institute, Salt Lake City, Utah, United States of America
| | - Guy A. Zimmerman
- Program in Human Molecular Biology and Genetics, University of Utah, Salt Lake City, Utah, United States of America
| | - Patricia T. Bozza
- Laboratório De Imunofarmacologia, Instituto Oswaldo Cruz, Fiocruz, RJ, Brazil
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Platelet-activating factor receptor knockout mice are protected from MPTP-induced dopaminergic degeneration. Neurochem Int 2013; 63:121-32. [DOI: 10.1016/j.neuint.2013.05.010] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2013] [Revised: 05/16/2013] [Accepted: 05/26/2013] [Indexed: 11/20/2022]
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Vadas P, Perelman B. Effect of epinephrine on platelet-activating factor-stimulated human vascular smooth muscle cells. J Allergy Clin Immunol 2012; 129:1329-33. [PMID: 22460068 DOI: 10.1016/j.jaci.2012.02.027] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2011] [Revised: 02/19/2012] [Accepted: 02/22/2012] [Indexed: 11/27/2022]
Abstract
BACKGROUND Animal and human data show that platelet-activating factor (PAF) mediates the life-threatening manifestations of anaphylaxis. Although administration of epinephrine is the mainstay of therapy of acute anaphylaxis, the interaction between epinephrine and PAF has not been studied. In particular, the effect of the timing of epinephrine administration on the action of PAF has not been examined. OBJECTIVE Using human vascular smooth muscle cells (HVSMCs), we examined the effect of timing of epinephrine addition on the action of PAF. METHODS The effect of epinephrine on PAF-mediated prostaglandin E(2) (PGE(2)) release from human aortic smooth muscle cells was examined. Epinephrine was added at various times before and after PAF stimulation. RESULTS HVSMCs stimulated with PAF released PGE(2) in a concentration- and time-dependent manner. Whereas preincubation of HVSMCs with epinephrine before the addition of PAF suppressed PGE(2) release, treatment with epinephrine after PAF stimulation was less effective with time after PAF stimulation. PGE(2) release was suppressed by means of preincubation with 8-bromo-cyclic AMP and forskolin. CONCLUSIONS PAF induced PGE(2) release from HVSMCs in a concentration- and time-dependent manner, and early addition of epinephrine was essential for the control of PAF-induced PGE(2) release. Epinephrine was most effective when administered before stimulation with PAF but was progressively less effective with time after PAF stimulation.
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Affiliation(s)
- Peter Vadas
- Department of Medicine, Division of Allergy and Clinical Immunology, St Michael's Hospital, University of Toronto, Toronto, Ontario, Canada.
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Nordin N, Jalil J, Jantan I, Murad S. Platelet-activating factor (PAF) receptor binding activity of the roots of Enicosanthellum pulchrum. PHARMACEUTICAL BIOLOGY 2012; 50:284-290. [PMID: 22103812 DOI: 10.3109/13880209.2011.602416] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
CONTEXT Enicosanthellum pulchrum (King) Heusden (Annonaceae) is a coniferous tree that is confined to mountain forests. The chemical constituents of this species have been studied previously; however, its biological activity has never been investigated before and is reported here for the first time. OBJECTIVE The extracts, fractions and compounds from the roots of E. pulchrum were investigated for their inhibitory effects on platelet-activating factor (PAF) receptor binding to rabbit platelets using (3)H-PAF as a ligand. MATERIALS AND METHODS The PAF receptor binding inhibitory effect using rabbit platelets was determined in vitro by measuring the difference between total amount of bound (3)H-PAF in the presence and the absence of excess unlabelled PAF. The compounds were isolated by bioassay-guided fractionation and their structures were elucidated by spectroscopic techniques. RESULTS AND DISCUSSION Among the extracts tested, the ethyl acetate extract was the most active with 85.6% inhibition, while hexane and methanol extracts showed 40.2 and 42.5% inhibition, respectively. Fractionation of the ethyl acetate extract using vacuum liquid chromatography (VLC) yielded six fractions AEA(I--VI). Chromatography fraction AEA(VI) yielded a new compound, 1-(2',3',4'-trimethoxyphenyl)hexan-1-ol, while fraction AEA(III) afforded three compounds, namely liriodenine, cleistopholine and dehydroanonaine. 1-(2',3',4'-Trimethoxyphenyl)hexan-1-ol, cleistopholine and dehydroanonaine showed relatively strong inhibition with IC(50) values of 26.6, 50.2 and 45.4 µM, respectively. CONCLUSION The results suggest that these compounds could be responsible for the PAF antagonistic activity of the ethyl acetate extract of this plant.
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Affiliation(s)
- Noraziah Nordin
- Faculty of Pharmacy, Universiti Kebangsaan Malaysia, Jalan Raja Muda Abd. Aziz, 50300 Kuala Lumpur, Malaysia
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Howard KM, Abdel-Al M, Ditmyer M, Patel N. Lipopolysaccharide and platelet-activating factor stimulate expression of platelet-activating factor acetylhydrolase via distinct signaling pathways. Inflamm Res 2011; 60:735-44. [PMID: 21432021 DOI: 10.1007/s00011-011-0326-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2010] [Revised: 02/22/2011] [Accepted: 03/03/2011] [Indexed: 11/30/2022] Open
Abstract
OBJECTIVES This study was designed to investigate and characterize the ability of platelet-activating factor (PAF) to induce the expression of platelet-activating factor acetylhydrolase (PAF-AH). METHODS Ribonuclease protection assays and quantitative real-time PCR were used to investigate the ability of lipopolysaccharide (LPS) and PAF to regulate PAF-AH mRNA expression in human monocyte-macrophage 6 (MM6) cells. Pharmacological inhibitors of mitogen activated protein kinases (MAPK) and PAF receptor antagonists were used to investigate the mechanism of regulation of PAF-AH. RESULTS PAF-AH mRNA levels were increased upon exposure to LPS or PAF in a dose-dependent manner. LPS elicited a more potent and rapid increase in PAF-AH expression than the PAF-stimulated response. However, when administered concomitantly, PAF augmented the LPS-stimulated response. LPS-stimulated PAF-AH expression was susceptible to partial inhibition by a p38 MAPK inhibitor and PAF receptor antagonists. PAF-induced up-regulation of PAF-AH levels was solely mediated via the PAF receptor and was p38 MAPK-independent. CONCLUSION The proinflammatory mediators, LPS and PAF, increased levels of PAF-AH mRNA via distinct signaling pathways.
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Affiliation(s)
- Katherine M Howard
- Department of Biomedical Sciences, University of Nevada Las Vegas School of Dental Medicine, 1001 Shadow Lane, Las Vegas, Nevada 89106, USA.
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Xu LF, Xu C, Mao ZQ, Teng X, Ma L, Sun M. Disruption of the F-actin cytoskeleton and monolayer barrier integrity induced by PAF and the protective effect of ITF on intestinal epithelium. Arch Pharm Res 2011; 34:245-51. [PMID: 21380808 DOI: 10.1007/s12272-011-0210-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2009] [Revised: 07/28/2010] [Accepted: 07/31/2010] [Indexed: 01/30/2023]
Abstract
To explore whether platelet-activating factor (PAF) can disrupt the intestinal epithelial barrier directly and is associated with structural alterations of the F-actin-based cytoskeleton, and to observe the protective effect of intestinal trefoil factor (ITF), we establish an intestinal epithelia barrier model using Caco-2 cells in vitro. Transepithelial electrical resistance and unidirectional flux of lucifer yellow were measured to evaluate barrier permeability; immunofluorescent staining and flow cytometry were applied to observe morphological alterations and to quantify proteins of the F-actin cytoskeleton: the tight junction marker ZO-1 and Claudin-1 were observed using immunofluorescent staining. PAF significantly increased paracellular permeability, at the same time, F-actin and tight junction proteins were disrupted. It was thought that ITF could reverse the high permeability by restoring normal F-actin, ZO-1 and Claudin-1 structures. These results collectively demonstrated that PAF plays an important role in the regulation of mucosal permeability and the effects of PAF are correlated with structural alterations of the F-actin-based cytoskeleton and of tight junctions. ITF can protect intestinal epithelium against PAF-induced disruption by restricting the rearrangement of the F-actin cytoskeleton and of tight junctions.
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Affiliation(s)
- Ling-fen Xu
- Department of Pediatrics, Shengjing Hospital of China Medical University, Shenyang, China
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Wakamoto S, Fujihara M, Takahashi D, Niwa K, Sato S, Kato T, Azuma H, Ikeda H. Enhancement of endothelial permeability by coculture with peripheral blood mononuclear cells in the presence of HLA Class II antibody that was associated with transfusion-related acute lung injury. Transfusion 2010; 51:993-1001. [PMID: 20977481 DOI: 10.1111/j.1537-2995.2010.02910.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BACKGROUND HLA Class II antibody-initiated activation of monocytes possessing the corresponding antigen is thought to participate in the pathogenesis of transfusion-related acute lung injury (TRALI). Pulmonary edema, a hallmark of TRALI, is caused by increasing vascular permeability. STUDY DESIGN AND METHODS To investigate the contribution of HLA Class II antibody and monocytes to the development of pulmonary edema in TRALI, we studied whether the permeability of human lung microvascular endothelial cells (HMVECs) could be enhanced by coculturing HMVECs with peripheral blood mononuclear cells (PBMNCs) in the presence of HLA Class II antibody-containing plasma, which was implicated in TRALI (anti-HLA-DR plasma). In addition, similar experiments were performed with human umbilical vein endothelial cells (HUVECs). The endothelial permeability to fluoresceinated dextran, which was added from the start of coculture, was measured. RESULTS The coculture of HMVECs or HUVECs with PBMNCs in the presence of anti-HLA-DR plasma resulted in the increase of endothelial permeability in the corresponding antigen-antibody-dependent manner. CV-3988, a platelet-activating factor (PAF) receptor antagonist, almost completely suppressed the increase in endothelial permeability. Neutralizing antibodies to tumor necrosis factor (TNF)-α alone and simultaneous addition of the antibodies to TNF-α and interleukin (IL)-1β to the coculture partially suppressed the permeability increase of HMVECs and HUVECs, respectively. CONCLUSIONS HLA Class II antibody and monocytes in the corresponding antigen-antibody combination caused the enhancement of endothelial permeability. PAF, TNF-α, and/or IL-1β might be involved in the endothelial permeability increase. HLA Class II antibody-initiated monocyte activation could lead to the development of pulmonary edema in TRALI.
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The endothelium: physiological functions and role in microcirculatory failure during severe sepsis. Intensive Care Med 2010; 36:1286-98. [DOI: 10.1007/s00134-010-1893-6] [Citation(s) in RCA: 149] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2009] [Accepted: 03/08/2010] [Indexed: 01/20/2023]
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Furukawa S, Urabe H, Nagai Y, Sameshima H, Ikenoue T, Sato Y. A rare case of amniotic fluid embolism with massive platelet aggregations in pulmonary capillaries. J Obstet Gynaecol Res 2010; 36:397-400. [DOI: 10.1111/j.1447-0756.2009.01151.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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23
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Karantonis HC, Gribilas G, Stamoulis I, Giaginis C, Spiliopoulou C, Kouraklis G, Demopoulos C, Theocharis SE. Platelet-activating factor involvement in thioacetamide-induced experimental liver fibrosis and cirrhosis. Dig Dis Sci 2010; 55:276-84. [PMID: 19242794 DOI: 10.1007/s10620-009-0745-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/04/2008] [Accepted: 01/27/2009] [Indexed: 12/13/2022]
Abstract
Platelet-activating factor (PAF) is a potent lipid inflammatory mediator acting on cells through its specific receptor. Plasma PAF-acetylhydrolase (PAF-AH) is the main enzyme that inactivates PAF in blood, participating in its homeostasis. The objective of this study was to investigate the involvement of PAF in the liver fibrotic process using an experimental animal model. Liver fibrosis was induced in adult male Wistar rats by administration of thioacetamide (TAA) in drinking water (300 mg/l) for three months. The animals were sacrificed at time 0 (control group) and after 1, 2, and 3 months. PAF levels in liver and blood and PAF-AH activity in plasma were determined. Liver histopathological examination was also performed. TAA administration resulted in progressively increased liver fibrosis, leading finally to the formation of cirrhotic nodules in the liver. Throughout the experiment PAF levels in liver tissue remained stable. "Total" ("free" plus "bound") PAF levels in blood decreased, reaching statistically significant differences in the first and third months compared with the control group (P < 0.05). "Free" PAF levels in blood were higher at one month (P < 0.05) and decreased gradually thereafter. In all treated groups, "bound" PAF levels in blood decreased whereas plasma PAF-AH activity increased (P < 0.05) compared with the control group. Our data indicated alterations of PAF levels in blood and PAF-AH activity during fibrosis induction, implicating participation of PAF in the liver fibrotic process.
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Affiliation(s)
- Haralabos C Karantonis
- Department of Forensic Medicine and Toxicology, School of Medicine, National and Kapodistrian University of Athens, 75 Mikras Asias str, 11527 Goudi, Athens, Greece
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24
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Jeong YI, Jung ID, Lee CM, Chang JH, Chun SH, Noh KT, Jeong SK, Shin YK, Lee WS, Kang MS, Lee SY, Lee JD, Park YM. The novel role of platelet-activating factor in protecting mice against lipopolysaccharide-induced endotoxic shock. PLoS One 2009; 4:e6503. [PMID: 19652714 PMCID: PMC2714981 DOI: 10.1371/journal.pone.0006503] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2009] [Accepted: 06/25/2009] [Indexed: 12/19/2022] Open
Abstract
Background Platelet-activating factor (PAF) has been long believed to be associated with many pathophysiological processes during septic shock. Here we present novel activities for PAF in protecting mice against LPS-mediated endotoxic shock. Principal Findings In vivo PAF treatment immediately after LPS challenge markedly improved the survival rate against mortality from endotoxic shock. Administration of PAF prominently attenuated LPS-induced organ injury, including profound hypotension, excessive polymorphonuclear neutrophil infiltration, and severe multiple organ failure. In addition, PAF treatment protects against LPS-induced lymphocytes apoptosis. These protective effects of PAF was correlated with significantly decreases in the production of the inflammatory mediators such as TNF-α, IL-1β, IL-12, and IFN-γ, while increasing production of the anti-inflammatory cytokine IL-10 in vivo and in vitro. Conclusions Taken together, these results suggest that PAF may protect mice against endotoxic shock via a complex mechanism involving modulation of inflammatory and anti-inflammatory mediators.
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Affiliation(s)
- Young-Il Jeong
- Department of Microbiology, College of Natural Science, Pusan National University, Geumjeong-Gu, Busan, Korea
- Department of Microbiology and Immunology and National Research Laboratory of Dendritic Cell Differentiation & Regulation, Medical Research Institute, College of Medicine, Pusan National University, Seo-gu, Busan, Korea
| | - In Duk Jung
- Department of Microbiology and Immunology and National Research Laboratory of Dendritic Cell Differentiation & Regulation, Medical Research Institute, College of Medicine, Pusan National University, Seo-gu, Busan, Korea
| | - Chang-Min Lee
- Department of Microbiology and Immunology and National Research Laboratory of Dendritic Cell Differentiation & Regulation, Medical Research Institute, College of Medicine, Pusan National University, Seo-gu, Busan, Korea
| | - Jeong Hyun Chang
- Department of Clinical Laboratory Science, Daegu Haany University, College of Health & Therapy, Gyeongsangbuk-do, Gyeongsan, Korea
| | - Sung Hak Chun
- Department of Microbiology and Immunology and National Research Laboratory of Dendritic Cell Differentiation & Regulation, Medical Research Institute, College of Medicine, Pusan National University, Seo-gu, Busan, Korea
| | - Kyung Tae Noh
- Department of Microbiology and Immunology and National Research Laboratory of Dendritic Cell Differentiation & Regulation, Medical Research Institute, College of Medicine, Pusan National University, Seo-gu, Busan, Korea
| | - Soo kyung Jeong
- Department of Microbiology and Immunology and National Research Laboratory of Dendritic Cell Differentiation & Regulation, Medical Research Institute, College of Medicine, Pusan National University, Seo-gu, Busan, Korea
| | - Yong Kyoo Shin
- Department of Pharmacology, College of Medicine, Chung-ang University, Seoul, Korea
| | - Won Suk Lee
- Department of Pharmacology, College of Medicine, Pusan National University, Seo-gu, Busan, Korea
| | - Mi Sun Kang
- Department of Pharmacology, College of Medicine, Pusan National University, Seo-gu, Busan, Korea
| | - Sang-Yull Lee
- Department of biochemistry, College of Medicine, Pusan National University, Seo-gu, Busan, Korea
| | - Jae-Dong Lee
- Department of Microbiology, College of Natural Science, Pusan National University, Geumjeong-Gu, Busan, Korea
| | - Yeong-Min Park
- Department of Microbiology and Immunology and National Research Laboratory of Dendritic Cell Differentiation & Regulation, Medical Research Institute, College of Medicine, Pusan National University, Seo-gu, Busan, Korea
- * E-mail:
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Vasileiou I, Xanthos T, Koudouna E, Perrea D, Klonaris C, Katsargyris A, Papadimitriou L. Propofol: A review of its non-anaesthetic effects. Eur J Pharmacol 2009; 605:1-8. [DOI: 10.1016/j.ejphar.2009.01.007] [Citation(s) in RCA: 173] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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Schenkein HA, Barbour SE, Tew JG. Cytokines and inflammatory factors regulating immunoglobulin production in aggressive periodontitis. Periodontol 2000 2007; 45:113-27. [PMID: 17850452 DOI: 10.1111/j.1600-0757.2007.00214.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- Harvey A Schenkein
- Department of Periodontics, Virginia Commonwealth University, School of Dentistry, Richmond, VA, USA
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Guerra CT, Caini P, Giannini C, Giannelli F, Gragnani L, Petrarca A, Solazzo V, Monti M, Laffi G, Zignego AL. Effect of chronic hepatitis C virus infection on inflammatory lipid mediators. Dig Liver Dis 2007; 39 Suppl 1:S76-82. [PMID: 17936229 DOI: 10.1016/s1590-8658(07)80016-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
BACKGROUND Platelet-activating factor (PAF), a powerful phospholipid mediator of inflammation, is degraded by plasma PAF-acetyl-hydxolase (pPAF-AH), an enzyme which circulates in serum mainly in a complex with lipoproteins that confer its biological activity. Hepatitis C virus (HCV) is linked to lipoproteins in serum too. Reduced pPAF-AH activity was observed in several diseases, including systemic vasculitis. AIM To evaluate if chronic HCV infection could alter pPAF-AH physiological functions. SUBJECTS 145 subjects were studied: 56 HCV- and 52 HBV-infected patients (pathologic controls); 37 healthy subjects (healthy controls). METHODS pPAF-AH activity, PAF and Apo B100 titers were determined in plasma; enzyme expression levels were evaluated in monocyte-derived macrophages. HCV-RNA was detected in plasma, peripheral blood mononuclear cells and liver samples. RESULTS HCV-infected patients showed an increase of PAF levels following a significant decrease of pPAF-AH activity. A recovery of pPAF-AH activity occurs only in patients who clear HCV after the antiviral treatment. Expression levels of pPAF-AH mRNA and Apo B100 titers were not modified in HCV patients in comparison to controls. CONCLUSION In light of these results, it is tempting to hypothesize that during chronic HCV infection, the PAF/pPAF-AH system may be altered and this condition may contribute to HCV-related vascular damage.
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Affiliation(s)
- Cristina Tosti Guerra
- Department of Internal Medicine, Center for the Study of Systemic Manifestations of Hepatitis Viruses MaSVE, University of Florence, Florence, Italy
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Winkler K, Hoffmann MM, Winkelmann BR, Friedrich I, Schäfer G, Seelhorst U, Wellnitz B, Wieland H, Boehm BO, März W. Lipoprotein-associated phospholipase A2 predicts 5-year cardiac mortality independently of established risk factors and adds prognostic information in patients with low and medium high-sensitivity C-reactive protein (the Ludwigshafen risk and cardiovascular health study). Clin Chem 2007; 53:1440-7. [PMID: 17573419 DOI: 10.1373/clinchem.2007.086298] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
BACKGROUND Lipoprotein-associated phospholipase A(2) (LpPLA(2)), also denoted as platelet-activating factor acetylhydrolase, is a lipoprotein-bound enzyme involved in inflammation and atherosclerosis. In this cohort study we investigated LpPLA(2) activity to predict cardiac mortality in patients scheduled for coronary angiography. METHODS LpPLA(2) activity was determined in 2513 patients with and in 719 patients without angiographically confirmed coronary artery disease (CAD). RESULTS During the median observation period of 5.5 years, 501 patients died. In patients with tertiles of LpPLA(2) activity of 420-509 U/L or >or=510 U/L, unadjusted hazard ratios (HRs) for cardiac death were 1.7 (95% CI 1.3-2.4; P = 0.001), and 1.9 (95% CI 1.4-2.5; P <0.001), respectively, compared with patients with LpPLA(2) activity <or=419 U/L. After we accounted for established risk factors and included angiographic CAD status, high-sensitivity C-reactive protein (hsCRP), and N-terminal pro-B-type natriuretic peptide, the 3rd tertile of LpPLA(2) activity predicted cardiac 5-year mortality with an HR of 2.0 (95% CI 1.4-3.1; P = 0.001). LpPLA(2) activity increased the adjusted risk for cardiac death by 2-fold in patients with hsCRP <3 mg/L in the 2nd (HR 2.4, 95% CI 1.4-4.2; P = 0.002) and 3rd (HR 2.1, 95% CI 1.1-4.0; P = 0.02) tertiles of LpPLA(2) activity and in patients with hsCRP of 3-10 mg/L in the 3rd tertile (HR 1.9, 95% CI 1.0-3.6; P = 0.03) of LpPLA(2) activity. CONCLUSIONS LpPLA(2) activity predicts risk for 5-year cardiac mortality independently from established risk factors and indicates risk for cardiac death in patients with low and medium-high hsCRP concentrations. Therefore, LpPLA(2) activity may provide information for the identification and management of patients at risk beyond established risk stratification strategies.
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Affiliation(s)
- Karl Winkler
- Department of Clinical Chemistry, University Medical Center Freiburg, Germany.
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Shin CR, Moores J, Best AM, Tew JG, Schenkein HA, Barbour SE. Differential platelet-activating factor synthesis by monocytes and polymorphonuclear leukocytes from subjects with localized aggressive periodontitis. J Periodontal Res 2007; 42:202-11. [PMID: 17451539 DOI: 10.1111/j.1600-0765.2006.00933.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BACKGROUND AND OBJECTIVE Platelet-activating factor is elevated in localized aggressive periodontitis. We previously demonstrated that the elevated level of platelet-activating factor in localized aggressive periodontitis is at least partially attributable to low levels of platelet-activating factor acetylhydrolase, the enzyme that catabolizes platelet-activating factor. The objective of this study was to determine if platelet-activating factor synthesis was also elevated in localized aggressive periodontitis. To test this, platelet-activating factor synthesis was quantified in the monocytes and polymorphonuclear neutrophils of periodontally healthy patients and of subjects with localized aggressive periodontitis. MATERIAL AND METHODS Cells were labeled with [(3)H]acetate and treated with vehicle or stimulated with calcium ionophore A23187. Platelet-activating factor was extracted and quantified by scintillation counting. RESULTS For both subject groups, resting monocytes and polymorphonuclear neutrophils produced platelet-activating factor, and calcium ionophore A23187 stimulated platelet-activating factor production in both cell types. However, calcium ionophore A23187-activated monocytes from subjects with localized aggressive periodontitis produced less platelet-activating factor than did activated periodontally healthy monocytes (p < 0.0001), suggesting an aberrant calcium ionophore A23187 response in monocytes from subjects with localized aggressive periodontitis. Indeed, when the data were expressed as fold induction of platelet-activating factor synthesis in response to calcium ionophore A23187, monocytes from subjects with localized aggressive periodontitis exhibited only a fourfold increase in platelet-activating factor synthesis, whereas calcium ionophore A23187-stimulated monocytes from periodontally healthy, chronic periodontitis and generalized aggressive periodontitis subjects produced approximately 12 times more platelet-activating factor than did resting monocytes. In contrast, both resting and activated localized aggressive periodontitis polymorphonuclear neutrophils synthesized more platelet-activating factor than did periodontally healthy polymorphonuclear neutrophils. CONCLUSION These data suggest that high levels of platelet-activating factor in subjects with localized aggressive periodontitis result from both increased synthesis and reduced catabolism. While localized aggressive periodontitis polymorphonuclear neutrophils contribute to increased platelet-activating factor mass through synthesis, the contribution of monocytes is probably the result of reduced catabolism by platelet-activating factor acetylhydrolase.
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Affiliation(s)
- C R Shin
- Department of Biochemistry, Virginia Commonwealth University, Richmond, VA 23298-0614, USA
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Caini P, Guerra CT, Giannini C, Giannelli F, Gragnani L, Petrarca A, Solazzo V, Monti M, Laffi G, Zignego AL. Modifications of plasma platelet-activating factor (PAF)-acetylhydrolase/PAF system activity in patients with chronic hepatitis C virus infection. J Viral Hepat 2007; 14:22-8. [PMID: 17212640 DOI: 10.1111/j.1365-2893.2006.00766.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/09/2022]
Abstract
Hepatitis C virus (HCV) chronically infects about 200 million individuals worldwide and leads to severe liver and lymphatic diseases. HCV circulates in the serum, associated with apoB-containing lipoproteins. Platelet-activating factor (PAF), a pro-inflammatory mediator, is mainly modulated by plasma PAF-acetylhydrolase (pPAF-AH), associated with ApoB100-containing low-density lipoproteins (LDL). The aim of the study was to evaluate the potential effects of chronic HCV infection on the PAF/pPAF-AH system. HCV-RNA was detected in plasma, peripheral blood mononuclear cells (PBMC) and liver samples. Plasma PAF levels, pPAF-AH activity, ApoB100 serum titres and pPAF-AH mRNA levels in cultured macrophages were determined. Plasma PAF levels were significantly higher and pPAF-AH activity was significantly lower in HCV patients than in controls. No significant modifications of pPAF-AH mRNA in macrophages or in ApoB100 values were observed in HCV patients compared with controls. Patients who cleared HCV after antiviral treatment showed a complete restoration of pPAF-AH activity and significant decrease of PAF levels during the follow-up. No data exist about the PAF/pPAF-AH system behaviour during HCV infection. This study shows that in HCV patients modifications of pPAF-AH activity/PAF levels take place and that HCV clearance restored pPAF-AH activity. This suggests that circulating viral particles play a role in PAF/pPAF-AH system modifications and such an alteration could be involved in HCV-related damage.
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Affiliation(s)
- P Caini
- Department of Internal Medicine, Center for the Study of Systemic Manifestations of Hepatitis Viruses MASVE and Higher Education Research and Transfer Center DENOTHE, University of Florence, Florence, Italy
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Gorgas K, Teigler A, Komljenovic D, Just WW. The ether lipid-deficient mouse: Tracking down plasmalogen functions. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2006; 1763:1511-26. [PMID: 17027098 DOI: 10.1016/j.bbamcr.2006.08.038] [Citation(s) in RCA: 157] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2006] [Revised: 08/15/2006] [Accepted: 08/23/2006] [Indexed: 10/24/2022]
Abstract
Chemical and physico-chemical properties as well as physiological functions of major mammalian ether-linked glycerolipids, including plasmalogens were reviewed. Their chemical structures were described and their effect on membrane fluidity and membrane fusion discussed. The recent generation of mouse models with ether lipid deficiency offered the possibility to study ether lipid and particularly plasmalogen functions in vivo. Ether lipid-deficient mice revealed severe phenotypic alterations, including arrest of spermatogenesis, development of cataract and defects in central nervous system myelination. In several cell culture systems lack of plasmalogens impaired intracellular cholesterol distribution affecting plasma membrane functions and structural changes of ER and Golgi cisternae. Based on these phenotypic anomalies that were accurately described conclusions were drawn on putative functions of plasmalogens. These functions were related to cell-cell or cell-extracellular matrix interactions, formation of lipid raft microdomains and intracellular cholesterol homeostasis. There are several human disorders, such as Zellweger syndrome, rhizomelic chondrodysplasia punctata, Alzheimer's disease, Down syndrome, and Niemann-Pick type C disease that are distinguished by altered tissue plasmalogen concentrations. The role plasmalogens might play in the pathology of these disorders is discussed.
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Affiliation(s)
- Karin Gorgas
- Institut für Anatomie und Zellbiologie, Abteilung Medizinische Zellbiologie, Im Neuenheimer Feld 307, D-69120 Heidelberg, Germany
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Karasawa K. Clinical aspects of plasma platelet-activating factor-acetylhydrolase. Biochim Biophys Acta Mol Cell Biol Lipids 2006; 1761:1359-72. [PMID: 17049457 DOI: 10.1016/j.bbalip.2006.06.017] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2006] [Accepted: 06/15/2006] [Indexed: 11/25/2022]
Abstract
Plasma platelet-activating factor (PAF)-acetylhydrolase (PAF-AH), which is characterized by tight association with plasma lipoproteins, degrades not only PAF but also phospholipids with oxidatively modified short fatty acyl chain esterified at the sn-2 position. Production and accumulation of these phospholipids are associated with the onset of inflammatory diseases and preventive role of this enzyme has been evidenced by many recent studies including prevalence of the genetic deficiency of the enzyme in the patients and therapeutic effects of treatment with recombinant protein or gene transfer. With respect to the atherosclerosis, however, it is not fully cleared whether this enzyme plays an anti-atherogenic role or pro-atherogenic role because plasma PAF-AH also might produce lysophosphatidylcholine (LysoPC) and oxidatively modified nonesterified fatty acids with potent pro-inflammatory and pro-atherogenic bioactivities. These dual roles of plasma PAF-AH might be regulated by the altered distribution of the enzyme between low density lipoprotein (LDL) and high density lipoprotein (HDL) particles because HDL-associated enzymes are considered to contribute to the protection of LDL from oxidative modification. This review focuses on the recent findings which address the role of this enzyme in the human diseases especially including asthma, septic shock and atherosclerosis.
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Affiliation(s)
- Ken Karasawa
- Laboratory of Molecular Pharmaceutics, Faculty of Pharmaceutical Sciences, Teikyo University, Sagamihara, Kanagawa 199-0195, Japan.
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Moreno SE, Alves-Filho JC, Rios-Santos F, Silva JS, Ferreira SH, Cunha FQ, Teixeira MM. Signaling via platelet-activating factor receptors accounts for the impairment of neutrophil migration in polymicrobial sepsis. THE JOURNAL OF IMMUNOLOGY 2006; 177:1264-71. [PMID: 16818786 DOI: 10.4049/jimmunol.177.2.1264] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Sepsis is a systemic inflammatory response that results from the inability of the immune system to limit bacterial spread during an ongoing infection. Recently, we have documented an impaired neutrophil migration toward the infectious focus in severe sepsis. This impairment seems to be mediated by circulating cytokines, chemokines, and NO. Platelet-activating factor (PAF) plays an important role in the orchestration of different inflammatory reactions, including the release of cytokines, chemokines, and free radicals. Using a PAFR antagonist, PCA-4248, and PAFR-deficient mice, we investigated whether signaling via PAFR was relevant for the failure of neutrophils to migrate to the site of infection after lethal sepsis caused by cecum ligation and puncture in mice. In PAFR-deficient mice or mice pretreated with PCA-4248 (5 mg/kg) and subjected to lethal sepsis, neutrophil migration failure was prevented, and bacterial clearance was more efficient. There was also reduced systemic inflammation (low serum cytokine levels), lower nitrate levels in plasma, and higher survival rate. Altogether, the results firmly establish a role for PAFR in mediating the early impairment of neutrophil migration toward the infectious focus. Blockade of PAFR may prevent the establishment of severe sepsis.
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Affiliation(s)
- Susana E Moreno
- Departamento de Farmacologia, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, São Paulo, Brazil
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Gomes RN, Bozza FA, Amâncio RT, Japiassú AM, Vianna RCS, Larangeira AP, Gouvêa JM, Bastos MS, Zimmerman GA, Stafforini DM, Prescott SM, Bozza PT, Castro-Faria-Neto HC. Exogenous platelet-activating factor acetylhydrolase reduces mortality in mice with systemic inflammatory response syndrome and sepsis. Shock 2006; 26:41-9. [PMID: 16783197 DOI: 10.1097/01.shk.0000209562.00070.1a] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Current evidence indicates that dysregulation of the host inflammatory response to infectious agents is central to the mortality of patients with sepsis and in those with systemic inflammatory response syndrome. Strategies to block inflammatory mediators, often with complicated outcomes, are currently being investigated as new adjuvant therapies for sepsis. Here, we determined if administration of recombinant platelet-activating factor (rPAF)-acetylhydrolase (rPAF-AH), an enzyme that inactivates PAF and PAF-like lipids, protects mice from inflammatory injury and death after administration of lipopolysaccharide (LPS) or cecal ligation and puncture (CLP). Administration of rPAF-AH increased plasma PAF-AH activity and reduced mortality in both models. Treatment with rPAF-AH increased peritoneal fluid levels of monocyte chemoattractant protein 1/CCL-2 and decreased interleukin 6 and migration inhibitory factor levels after LPS administration or CLP. Administration of a broad-spectrum antibiotic together with rPAF-AH was more protective than single treatment with either of these agents. The combined treatment was associated with reduced interleukin 6 levels in mice subjected to CLP. We observed acute decreases in plasma PAF-AH activity in mice subjected to CLP or challenged with LPS and in human patients with sepsis. We conclude that alterations in the endogenous PAF-AH contribute to the pathophysiology of sepsis and that administration of exogenous rPAF-AH reduces inflammatory injury and mortality in models relevant to the clinical syndrome. Variations in endogenous PAF-AH activity may potentially account for variable responses to exogenous rPAF-AH in previous clinical trials. Serial measurements of plasma PAF-AH activity in murine models demonstrate dynamic regulation of the endogenous enzyme, potentially explaining the variations in human subjects.
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Affiliation(s)
- Rachel N Gomes
- Laboratório de Imunofarmacologia, Departamento de Fisiologia e Farmacodinâmica, IOC, Fundação Oswaldo Cruz, Rio de Janeiro, RJ, Brazil
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Doi K, Okamoto K, Negishi K, Suzuki Y, Nakao A, Fujita T, Toda A, Yokomizo T, Kita Y, Kihara Y, Ishii S, Shimizu T, Noiri E. Attenuation of folic acid-induced renal inflammatory injury in platelet-activating factor receptor-deficient mice. THE AMERICAN JOURNAL OF PATHOLOGY 2006; 168:1413-24. [PMID: 16651609 PMCID: PMC1606605 DOI: 10.2353/ajpath.2006.050634] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Platelet-activating factor (PAF), a potent lipid mediator with various biological activities, plays an important role in inflammation by recruiting leukocytes. In this study we used platelet-activating factor receptor (PAFR)-deficient mice to elucidate the role of PAF in inflammatory renal injury induced by folic acid administration. PAFR-deficient mice showed significant amelioration of renal dysfunction and pathological findings such as acute tubular damage with neutrophil infiltration, lipid peroxidation observed with antibody to 4-hydroxy-2-hexenal (day 2), and interstitial fibrosis with macrophage infiltration associated with expression of monocyte chemoattractant protein-1 and tumor necrosis factor-alpha in the kidney (day 14). Acute tubular damage was attenuated by neutrophil depletion using a monoclonal antibody (RB6-8C5), demonstrating the contribution of neutrophils to acute phase injury. Macrophage infiltration was also decreased when treatment with a PAF antagonist (WEB2086) was started after acute phase. In vitro chemotaxis assay using a Boyden chamber demonstrated that PAF exhibits a strong chemotactic activity for macrophages. These results indicate that PAF is involved in pathogenesis of folic acid-induced renal injury by activating neutrophils in acute phase and macrophages in chronic interstitial fibrosis. Inhibiting the PAF pathway might be therapeutic to kidney injury from inflammatory cells.
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Affiliation(s)
- Kent Doi
- Department of Nephrology and Endocrinology, University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8655, Japan
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Stanimirovic D, Satoh K. Inflammatory mediators of cerebral endothelium: a role in ischemic brain inflammation. Brain Pathol 2006; 10:113-26. [PMID: 10668901 PMCID: PMC8098501 DOI: 10.1111/j.1750-3639.2000.tb00248.x] [Citation(s) in RCA: 219] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Brain inflammation has been implicated in the development of brain edema and secondary brain damage in ischemia and trauma. Adhesion molecules, cytokines and leukocyte chemoattractants released/presented at the site of blood-brain barrier (BBB) play an important role in mobilizing peripheral inflammatory cells into the brain. Cerebral endothelial cells (CEC) are actively engaged in processes of microvascular stasis and leukocyte infiltration by producing a plethora of pro-inflammatory mediators. When challenged by external stimuli including cytokines and hypoxia, CEC have been shown to release/express various products of arachidonic acid cascade with both vasoactive and pro-inflammatory properties, including prostaglandins, leukotrienes, and platelet-activating factor (PAF). These metabolites induce platelet and neutrophil activation and adhesion, changes in local cerebral blood flow and blood rheology, and increases in BBB permeability. Ischemic CEC have also been shown to express and release bioactive inflammatory cytokines and chemokines, including IL-1beta, IL-8 and MCP-1. Many of these mediators and ischemia in vitro and in vivo have been shown to up-regulate the expression of both selectin and Ig-families of adhesion molecules in CEC and to facilitate leukocyte adhesion and transmigration into the brain. Collectively, these studies demonstrate a pivotal role of CEC in initiating and regulating inflammatory responses in cerebral ischemia.
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Affiliation(s)
- D Stanimirovic
- Institute for Biological Sciences, National Research Council of Canada, Ottawa, ON.
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Papavasiliou EC, Gouva C, Siamopoulos KC, Tselepis AD. Erythrocyte PAF-acetylhydrolase activity in various stages of chronic kidney disease: effect of long-term therapy with erythropoietin. Kidney Int 2005; 68:246-55. [PMID: 15954914 DOI: 10.1111/j.1523-1755.2005.00399.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
BACKGROUND Erythrocytes represent an important component of the antioxidant capacity of blood, comprising, in particular, intracellular enzymes, including platelet-activating factor acetylhydrolase (PAF-AH) and glutathione peroxidase (Gpx). We evaluated the erythrocyte PAF-AH and Gpx activities in various stages of chronic kidney disease (CKD), and further investigated whether erythropoietin (EPO) administration in these patients has any influence on the enzyme activities. METHODS Thirty-six patients (19 men and 17 women) with CKD (stages 1 to 5) participated in the study. Thirteen of them presented with CKD stage 1 to 2 (group I), whereas 23 patients presented with CKD stage 3 to 5 and randomized into two groups (i.e., groups II and III). Patients of group II (N= 11) were administered EPO subcutaneously, 50 units per kg once per week. In group III (N= 12), EPO was initiated only when the hemoglobin (Hb) levels decreased during follow-up to less than 9 g/dL. All patients were seen on an outpatient basis at 2 and 4 months. Fifteen normolipidemic age- and sex-matched healthy volunteers also participated in the study and were used as controls. The PAF-AH and Gpx activities were determined in isolated washed erythrocytes. RESULTS The erythrocyte-associated PAF-AH and Gpx activities were higher in all CKD patient groups at baseline compared to controls, the groups II and III exhibiting significantly higher enzyme activities compared with group I. In all studied populations, both enzyme activities were negatively correlated with the creatinine clearance values. Importantly, the PAF-AH and Gpx activities were progressively decreased during the follow-up in patients not treated with EPO (group III), a phenomenon not observed in patients receiving EPO (group II), or in patients of group I. This reduction in enzyme activities was positively correlated with the decrease in the creatinine clearance values in patients of group III. CONCLUSION Significant alterations in the erythrocyte-associated PAF-AH and Gpx activities related to the disease stage are observed in CKD patients. Administration of EPO prevented the reduction in enzyme activities observed during the progression of the renal insufficiency, thus preserving the erythrocyte defense mechanisms against oxidative stress.
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Affiliation(s)
- Eleni C Papavasiliou
- Laboratory of Biochemistry, Department of Chemistry, Medical School, University of Ioannina, Ioannina, Greece
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38
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Sumita C, Yamane M, Matsuda T, Maeda M, Nariai T, Fujio Y, Azuma J. Platelet activating factor induces cytoskeletal reorganization through Rho family pathway in THP-1 macrophages. FEBS Lett 2005; 579:4038-42. [PMID: 16004986 DOI: 10.1016/j.febslet.2005.06.022] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2005] [Revised: 06/02/2005] [Accepted: 06/13/2005] [Indexed: 10/25/2022]
Abstract
In the process of atherosclerosis, platelet activating factor (PAF) promotes the infiltration of inflammatory cells into atherosclerotic plaque by modulating their cytoskeleton. Here, we examined whether Rho family proteins are involved in PAF-induced cytoskeletal reorganization in THP-1 macrophages. PAF stimulation rapidly induced cell elongation, accompanied by filopodia formation. The inhibition of Rho family proteins by the overexpression of Rho-GDI attenuated the PAF-mediated morphological changes. Both RhoA and Cdc42 were activated in response to PAF. Inhibition of RhoA or Cdc42 by dominant negative mutants abrogated morphological changes induced by PAF. Collectively, PAF regulates cytoarchitecture through Rho family proteins in macrophages.
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Affiliation(s)
- Chinuyo Sumita
- Department of Clinical Evaluation of Medicines and Therapeutics, Graduate School of Pharmaceutical Sciences, Osaka University, Japan
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39
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Minami T, Suzuki H, Takeuchi T, Uemura S, Sugatani J, Yoshikawa N. A polymorphism in plasma platelet-activating factor acetylhydrolase is involved in resistance to immunoglobulin treatment in Kawasaki disease. J Pediatr 2005; 147:78-83. [PMID: 16027700 DOI: 10.1016/j.jpeds.2005.03.037] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
OBJECTIVE To investigate whether reduced levels of plasma platelet-activating factor acetylhydrolase (PAF-AH) as a result of a genetic polymorphism are involved in the pathogenesis of Kawasaki disease (KD). STUDY DESIGN The frequency of a V279F polymorphism (G/T transversion) in the PAF-AH gene was quantified in 76 Japanese children with KD and 112 healthy Japanese adults using the allele-specific polymerase chain reaction (PCR). Associations between genotype, clinical features, and resistance to intravenous immunoglobulin (IVIG) were investigated in the patients with KD. Plasma PAF-AH activity was measured by using [3H]-acetyl-PAF. RESULTS There were no significant differences in genotype frequency between patients and controls (P = .51). Compared with the GG (normal genotype) group, significantly more patients in the GT (heterozygous) +TT (homozygous deficient) group required additional IVIG (52% vs 14%, P = .001). The duration of fever and maximum serum C-reactive protein (CRP) levels also were significantly increased in the GT+TT group (P = .012 and .036, respectively), whereas plasma PAF-AH activity was significantly lower (P <.0001). CONCLUSION We conclude that the V279F polymorphism in the plasma PAF-AH gene and consequent enzymatic deficiency is one of the factors for IVIG nonresponse in Japanese patients with acute KD.
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Affiliation(s)
- Takaomi Minami
- Department of Pediatrics, Wakayama Medical University, Wakayama, Japan.
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40
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Castro Faria Neto HC, Stafforini DM, Prescott SM, Zimmerman GA. Regulating inflammation through the anti-inflammatory enzyme platelet-activating factor-acetylhydrolase. Mem Inst Oswaldo Cruz 2005; 100 Suppl 1:83-91. [PMID: 15962103 DOI: 10.1590/s0074-02762005000900014] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Platelet-activating factor (PAF) is one of the most potent lipid mediators involved in inflammatory events. The acetyl group at the sn-2 position of its glycerol backbone is essential for its biological activity. Deacetylation induces the formation of the inactive metabolite lyso-PAF. This deacetylation reaction is catalyzed by PAF-acetylhydrolase (PAF-AH), a calcium independent phospholipase A2 that also degrades a family of PAF-like oxidized phospholipids with short sn-2 residues. Biochemical and enzymological evaluations revealed that at least three types of PAF-AH exist in mammals, namely the intracellular types I and II and a plasma type. Many observations indicate that plasma PAF AH terminates signals by PAF and oxidized PAF-like lipids and thereby regulates inflammatory responses. In this review, we will focus on the potential of PAF-AH as a modulator of diseases of dysregulated inflammation.
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Affiliation(s)
- Hugo C Castro Faria Neto
- Laboratório de Imunofarmacologia, Departamento de Fisiologia e Farmacodinâmica, Instituto Oswaldo Cruz, Fiocruz, Rio de Janeiro, RJ, Brasil
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41
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Denham W, Norman J. Potential new therapies for the treatment of acute pancreatitis. Expert Opin Investig Drugs 2005; 8:973-82. [PMID: 15992099 DOI: 10.1517/13543784.8.7.973] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The treatment of acute pancreatitis has remained virtually unchanged for the past 50 years, in large part due to a poor understanding of the initial intracellular events. Furthermore, there is a lack of knowledge regarding the mediator(s) responsible for the progression of the disease from local pancreatic inflammation to a systemic inflammatory disease, as well as the mediator(s) responsible for distant organ dysfunction and failure. With recent advances in the pathophysiology of pancreatitis, in particular the role of the inflammatory mediators interleukin-1 beta, tumour necrosis factor alpha and platelet-activating factor, the potential for new effective therapies has been realised. At present, a number of inflammatory mediator antagonists are being tested in humans, with the hope that we may soon develop a specific treatment for a disease, which thus far, has none.
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Affiliation(s)
- W Denham
- Department of Surgery, MDC 16, University of South Florida, 12901 Bruce B. Downs Blvd, Tampa, FL 33612, USA.
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Winkler K, Winkelmann BR, Scharnagl H, Hoffmann MM, Grawitz AB, Nauck M, Böhm BO, März W. Platelet-activating factor acetylhydrolase activity indicates angiographic coronary artery disease independently of systemic inflammation and other risk factors: the Ludwigshafen Risk and Cardiovascular Health Study. Circulation 2005; 111:980-7. [PMID: 15710755 DOI: 10.1161/01.cir.0000156457.35971.c8] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
BACKGROUND Platelet-activating factor acetylhydrolase (PAF-AH), also denoted as lipoprotein-associated phospholipase A2, is a lipoprotein-bound enzyme that is possibly involved in inflammation and atherosclerosis. This study investigates the relationship of PAF-AH activity to angiographic coronary artery disease (CAD), the use of cardiovascular drugs, and other established risk factors. METHODS AND RESULTS PAF-AH activity, lipoproteins, sensitive C-reactive protein (sCRP), fibrinogen, serum amyloid A, and white blood cell count were determined in 2454 subjects with angiographically confirmed CAD and in 694 control subjects. PAF-AH activity was highly correlated with LDL cholesterol (r=0.517), apolipoprotein B (r=0.644), and non-HDL cholesterol (r=0.648) but not with sCRP or fibrinogen. PAF-AH activity was lower in women than in men and was affected by the intake of lipid-lowering drugs (-12%; P<0.001), aspirin (-6%; P<0.001), beta-blockers (-6%; P<0.001), and digitalis (+7%; P<0.001). Unlike sCRP, fibrinogen, and serum amyloid A, PAF-AH activity was not elevated in unstable angina, non-ST-elevation myocardial infarction, or ST-elevation myocardial infarction. When nonusers of lipid-lowering drugs were examined, PAF-AH activity was associated with the severity of CAD and the number of coronary vessels with significant stenoses. In individuals not taking lipid-lowering drugs and after adjustment for use of aspirin, beta-blocker, and digitalis, the odds ratio for CAD associated with increasing PAF-AH activity was 1.39 (95% CI 1.26 to 1.54, P<0.001), a finding that was robust against further adjustments. CONCLUSIONS PAF-AH activity is not an indicator of the systemic inflammation that accompanies acute coronary syndromes. PAF-AH activity is affected by a number of cardiovascular drugs; however, after such medication use was accounted for, PAF-AH activity was associated with angiographic CAD, complementary to sCRP and independently of established risk factors such as LDL cholesterol.
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Affiliation(s)
- Karl Winkler
- Department of Medicine, University of Freiburg, Freiburg, Germany.
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Abstract
This review is focused on the effects of histamine and platelet-activating factor (PAF) in allergic rhinitis and the plausible implications for therapy. Rhinitis is defined as a heterogeneous disorder resulting from an IgE-mediated reaction associated with nasal inflammation of variable intensity. Two phases of response are triggered by an IgE/allergen cross-linking event: the first is the release of preformed mediators such as histamine or interleukins from mast cells and basophils; the second begins when cells start producing lipid-derived mediators. One of these mediators is PAF. Apart from leukotrienes, PAF is perhaps the most potent inflammatory mediator in allergic rhinitis for inducing vascular leakage, a response that may contribute to the appearance of rhinorrhea and nasal congestion.
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Affiliation(s)
- V Alfaro
- Department of Physiology, University of Barcelona, Avda. Diagonal 645, 08028 Barcelona, Spain.
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Lee E, Lee SJ, Lee TY, Chang HW. cDNA Cloning and Expression of Biologically Active Platelet Activating Factor-Acetylhydrolase (PAF-AH) from Bovine Mammary Gland. Biol Pharm Bull 2005; 28:580-3. [PMID: 15802790 DOI: 10.1248/bpb.28.580] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Platelet activating factor (PAF)-acetylhydrolase (PAF-AH) is an enzyme that hydrolyzes the acetyl ester at the sn-2 position of PAF, and converts it to the inactive metabolite, lyso PAF. This enzyme is distributed widely in the intracellular as well as the extracellular matrix and is believed to be a defense mechanism that protects the host against the toxic effects of PAF and other biologically active oxidized phospholipids. Purification and expression of cDNA cloning of the intracellular and extracellular types of PAF-AH from several sources from different species have been reported. In this study, the cDNA for PAF-AH was cloned by reverse transcription (RT)-PCR from total RNA of bovine mammary gland. The complete amino acid sequences from the cDNA contains 444 amino acids and was identical to that of the PAF-AH isolated from the bovine spleen cDNA library except for two mismatches of amino acid residues (Thr-247 to Met and Ile-431 to Thr). Recombinant PAF-AH was expressed in HEK 293 cells, which exhibited enzyme activity in the in vitro assay system. Furthermore, recombinant bovine PAF-AH was identified by western blot using human plasma PAF-AH antibody as a monomeric polypeptide with a molecular weight of approximately 43 kDa. This protein can be applied to in vivo models to test its protective role against the deleterious PAF actions.
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Affiliation(s)
- Eunkyung Lee
- College of Pharmacy, Yeungnam University, Gyonsan, Korea
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45
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Wu A, Hinds CJ, Thiemermann C. High-density lipoproteins in sepsis and septic shock: metabolism, actions, and therapeutic applications. Shock 2004; 21:210-21. [PMID: 14770033 DOI: 10.1097/01.shk.0000111661.09279.82] [Citation(s) in RCA: 137] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Sepsis and septic shock are important causes of morbidity and lethality in noncoronary intensive care units. Circulating levels of high-density lipoproteins (HDLs) are reduced in sepsis/septic shock, and the magnitude of this reduction is positively correlated with the severity of the illness. The mechanisms underlying this phenomenon are incompletely understood, although increased levels of several acute-phase proteins, including serum amyloid A (SAA) and secretory phospholipase A2 (sPLA2), may contribute to the decrease in plasma HDLs. It has been suggested that HDLs possess anti-inflammatory properties and, hence, may play a crucial role in innate immunity by regulating the inflammatory response as well as being capable of reducing the severity of organ injury in animals and patients with septic shock. These protective effects of HDLs are mediated mainly via (a) lipopolysaccharide (LPS) binding and neutralization, (b) the HDL-associated enzymes, plasma paraoxonase (PON1) and platelet-activating factor acetylhydrolase (PAF-AH), which protect low-density lipoproteins against peroxidative damage, (c) inhibition of the expression of endothelial cell adhesion molecules and release of proinflammatory cytokines, which prevents inflammatory cell infiltration and subsequent multiple organ dysfunction, and (d) stimulation of the expression of endothelial nitric oxide synthase (eNOS). Thus, HDL exerts potent anti-inflammatory effects, some of which are independent of endotoxin binding and might be useful in the treatment of patients with not only sepsis/septic shock but also other conditions associated with an uncontrolled inflammatory response, such as ischemia-reperfusion injury and hemorrhagic shock.
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Affiliation(s)
- Aihua Wu
- Department of Anaesthesia, Beijing Hospital, Beijing 100730, PR China
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Sumita C, Maeda M, Fujio Y, Kim J, Fujitsu J, Kasayama S, Yamamoto I, Azuma J. Pioglitazone induces plasma platelet activating factor-acetylhydrolase and inhibits platelet activating factor-mediated cytoskeletal reorganization in macrophage. Biochim Biophys Acta Gen Subj 2004; 1673:115-21. [PMID: 15279882 DOI: 10.1016/j.bbagen.2004.04.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2003] [Revised: 03/29/2004] [Accepted: 04/02/2004] [Indexed: 11/18/2022]
Abstract
Platelet activating factor (PAF) is a key molecule for inflammation. To examine a role of peroxisome proliferator-activated receptor gamma (PPARgamma) in inflammatory reactions of atherosclerosis, we investigated the effects of 15-deoxy-(Delta12,14)-Prostaglandin J2 (15d-PGJ2) and pioglitazone, PPARgamma ligands, on plasma PAF-acetylhydrolase (PAF-AH) expression in THP-1 macrophages. PAF-AH mRNA and protein were up-regulated by the PPARgamma ligands. Prostaglandin F2alpha (PGF2alpha), a PARgamma inhibitor, abrogated the up-regulation of PAF-AH mRNA by pioglitazone, suggesting that PPARgamma activation is involved in the induction of PAF-AH by pioglitazone. As PAF promotes the cell motility with cytoskeletal reorganization, we investigated the effect of pioglitazone on PAF-mediated morphological changes in THP-1 macrophages. In the absence of pioglitazone, PAF promoted the elongation of actin cytoskeleton, which was inhibited by pretreatment with pioglitazone. In contrast, pioglitazone was not able to inhibit the morphological changes induced by C-PAF, a non-hydrolyzable PAF agonist. Thus, it is suggested that PAF-induced morphological changes could be inhibited by pioglitazone through PAF-AH, which rapidly hydrolyzed PAF. These data propose that PPARgamma/PAF-AH pathway is a clinical target for the prevention against atherosclerosis.
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Affiliation(s)
- Chinuyo Sumita
- Department of Clinical Evaluation of Medicines and Therapeutics, Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamada-oka, Suita City, Osaka 565-0871, Japan
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Fourcade O, Simon MF, Litt L, Samii K, Chap H. Propofol Inhibits Human Platelet Aggregation Induced by Proinflammatory Lipid Mediators. Anesth Analg 2004; 99:393-8, table of contents. [PMID: 15271713 DOI: 10.1213/01.ane.0000123491.08697.ca] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Lysophosphatidic acid (LPA), platelet-activating factor (PAF), and thromboxane A(2) are proinflammatory lipid mediators that activate surface receptors on platelets, producing increased intracellular calcium, which is necessary for aggregation. We investigated propofol's effect on platelet aggregation and intracellular calcium mobilization caused by these three agonists. Platelets from human volunteers were incubated in buffers containing LPA (1 microM), U46619 (thromboxane A(2) analog; 1 microM), or PAF (10 nM). Propofol emulsion or 2,6-diisopropylphenol (propofol without fat emulsion) dissolved in ethanol was added to achieve concentrations of propofol used clinically: 5 or 10 microg/mL. After 2 min, aggregation or intracellular calcium concentrations were measured with optical techniques. Propofol emulsion and propofol in ethanol produced similar inhibition of platelet aggregation induced by LPA, PAF, and U46619 in a dose-dependent fashion. LPA, PAF, and U46619 each caused significant increases in intracellular calcium that were not modified by propofol. Because propofol does not significantly alter intracellular calcium increases caused by receptor activation, inhibition appears to act distal to platelet receptors, inositol phosphate 3, and phospholipase C. Because the three lipid mediators play a key role in inflammation, their inhibition by propofol might be clinically important.
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Affiliation(s)
- Olivier Fourcade
- Service d'Anesthésie-Réanimation, Hôpital Purpan, University of Toulouse, Place du Docteur Baylac, 31059 Toulouse Cedex, France.
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Opal S, Laterre PF, Abraham E, Francois B, Wittebole X, Lowry S, Dhainaut JF, Warren B, Dugernier T, Lopez A, Sanchez M, Demeyer I, Jauregui L, Lorente JA, McGee W, Reinhart K, Kljucar S, Souza S, Pribble J. Recombinant human platelet-activating factor acetylhydrolase for treatment of severe sepsis: results of a phase III, multicenter, randomized, double-blind, placebo-controlled, clinical trial. Crit Care Med 2004; 32:332-41. [PMID: 14758145 DOI: 10.1097/01.ccm.0000108867.87890.6d] [Citation(s) in RCA: 128] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE Platelet-activating factor (PAF) and structurally-related oxidized phospholipids are proinflammatory mediators in systemic inflammatory states such as severe sepsis. The enzyme platelet-activating factor acetylhydrolase (PAF-AH) rapidly degrades PAF and oxidized phospholipids into inactive metabolites. Reduced PAF-AH activity has been observed in patients with severe sepsis and may contribute to their systemic inflammatory response and organ dysfunction. A previous clinical trial with recombinant human PAF-AH (rPAF-AH, Pafase) suggested that this treatment may decrease 28-day all-cause mortality in patients with severe sepsis. The current study was undertaken to confirm this result. DESIGN A prospective, randomized, double-blind, placebo-controlled, multicenter, international trial. SETTING One hundred forty-six intensive care units from nine countries. PATIENTS Approximately 2,522 patients were planned to be enrolled < or =12 hrs after the onset of severe sepsis. Eligible patients were randomized to receive either rPAF-AH 1.0 mg/kg or placebo administered intravenously once daily for five consecutive days. MEASUREMENTS AND MAIN RESULTS The study was terminated based on the recommendation of an independent data and safety monitoring committee after the second of three planned interim analyses, and the enrollment of 1,425 patients. rPAF-AH treatment was well tolerated among the 1,261 patients included in the interim analysis (643 rPAF-AH and 618 placebo), but did not decrease 28-day all-cause mortality compared with placebo (25% for rPAF-AH vs. 24% for placebo; relative risk, 1.03; 95% confidence interval, 0.85-1.25; p =.80). There were no statistically significant differences between treatment groups in any of the secondary efficacy end points. The overall incidence of adverse events was similar among rPAF-AH and placebo-treated patients, and no rPAF-AH-treated patients developed antibodies to PAF-AH. CONCLUSIONS rPAF-AH was well tolerated and not antigenic, but did not decrease 28-day all-cause mortality in patients with severe sepsis.
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Affiliation(s)
- Steven Opal
- Division of Infectious Diseases, Brown Medical School, Providence, RI, USA
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Rhee CK. Candidate???s Thesis: Platelet-Activating Factor???Induced Hearing Loss: Mediated by Nitric Oxide? Laryngoscope 2003; 113:2059-66. [PMID: 14660903 DOI: 10.1097/00005537-200312000-00001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVES/HYPOTHESIS Platelet-activating factor (PAF)in middle ear effusion is thought to induce hearing loss. The purpose of this study is to investigate the role of nitric oxide (NO) in the mechanism of PAF-induced hearing loss by studying the effects of PAF application on the round window membrane (RWM) with and without PAF-antagonist NO-blocker. STUDY DESIGN Longitudinal study on randomized guinea pigs using PAF to induce hearing loss. METHODS Guinea pigs were divided into four groups: PBS, PAF, PAF-antagonist, and L-NAME. The PBS group received phosphate buffered saline (PBS) and the PAF groups received 10, 20, and 40 microg of PAF soaked into gelfoam and placed on the RWM. PAF-antagonist (WEB 2170) and NOS inhibitor NG-nitro-l-arginine-methylester (L-NAME) were injected intraperitoneally prior to PAF 20 microg application on the RWM. The following three tests were performed on each animal group: Hearing was tested with an auditory brainstem response (ABR) test over 24 hours. At the end of 24 hours, cochlear hair cells were examined by scanning electron microscopy (SEM) and immunohistochemistry was carried out on the cochlea to test the expression of inducible nitric oxide synthase (iNOS). RESULTS The PAF group developed significant elevation of ABR threshold and cochlear hair cell damage in the SEM group as compared with the PBS control group. The PAF-antagonist (WEB 2170) and the L-NAME groups did not show significant elevation of ABR threshold and cochlear hair cell damage compared with the group administered PAF 20 microg, but in the PAF-antagonist group, the elevation of ABR threshold was significant compared with that of the PBS control group, whereas it was not significant compared with the PBS group in the L-NAME group. Strong expression of iNOS on cochlea was observed in the PAF group and lighter expression was seen in PBS, WEB 2170, and L-NAME groups. CONCLUSIONS This study demonstrated that PAF placed on the RWM induced hearing loss and cochlear hair cell damage. The PAF-antagonists and L-NAME prevented the PAF-induced hearing loss and inhibited iNOS expression in the cochlea. These findings suggest that the PAF-induced hearing loss caused by cochlear hair cell damage may have been mediated by NO. PAF-antagonists and L-NAME may have future therapeutic implications in preventing sensorineural hearing loss associated with chronic otitis media. The results of this study have significant potential clinical application.
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Affiliation(s)
- Chung-Ku Rhee
- Department of Otolaryngology-Head and Neck Surgery, Medical Laser Research Center, College of Medicine, Dankook University, Anseo-dong, Cheonan-city, Chungnam-do, Korea 330-714.
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Narahara H, Kawano Y, Nasu K, Yoshimatsu J, Johnston JM, Miyakawa I. Platelet-activating factor inhibits the secretion of platelet-activating factor acetylhydrolase by human decidual macrophages. J Clin Endocrinol Metab 2003; 88:6029-33. [PMID: 14671207 DOI: 10.1210/jc.2003-030706] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Abstract
To clarify the role of platelet-activating factor (PAF) in parturition, the effects of PAF on the secretion of PAF-acetylhydrolase (PAF-AH), a PAF-inactivating enzyme, by decidual macrophage populations were examined. The cells were isolated from human decidual tissue by enzymatic digestion, Ficoll-Paque centrifugation, or flow cytometric sorting. The nonhydrolyzable agonist of PAF, carbamyl-PAF (C-PAF), inhibited the secretion of PAF-AH by either decidual cells or flow cytometrically purified decidual macrophages. A specific PAF receptor antagonist, WEB 2086, blocked the C-PAF-induced inhibition. Lyso-PAF, a metabolite of PAF, had no effect on the enzyme secretion. An intracellular calcium channel blocker, bis-(o-aminophenoxy)-ethane-N,N,N',N'-tetraacetic acid, tetra(acetoxymethyl)-ester, partially blocked the inhibition by C-PAF, whereas extracellular calcium channel blockers, nifedipine and verapamil, were without effect. The inhibitory effect of C-PAF was also partially blocked by protein kinase C (PKC) inhibitors, sphingosine and H-7. A PKC activator, 12-O-tetradecanoylphobol 13-acetate, decreased the secretion of PAF-AH. The decrease was abolished by the addition of sphingosine and H-7. It is suggested that PAF inhibits the PAF-AH secretion by decidual macrophages and that the inhibitory action is mediated by a signal transduction mechanism involving intracellular calcium and PKC.
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Affiliation(s)
- Hisashi Narahara
- Department of Obstetrics and Gynecology, Oita Medical University, Hasama, Oita 879-5593, Japan.
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