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Pałgan K, Tretyn A. Platelet-activating factor as an endogenous cofactor of food anaphylaxis. Biofactors 2023; 49:976-983. [PMID: 37203358 DOI: 10.1002/biof.1956] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Accepted: 03/02/2023] [Indexed: 05/20/2023]
Abstract
Anaphylaxis is a severe, acute, life-threatening generalized or systemic hypersensitivity reaction. The incidence of anaphylaxis is increasing worldwide, with medications and food contributing to most cases. Physical exercise, acute infections, drugs, alcohol, and menstruation are the external cofactors associated with more severe systemic reaction. The aim of this review is to show that platelet-activating factor contributes to the development of severe anaphylactic reaction, and even to anaphylactic shock.
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Affiliation(s)
- Krzysztof Pałgan
- Department of Allergology, Clinical Immunology and Internal Diseases, Collegium Medicum in Bydgoszcz, Nicolaus Copernicus University, Bydgoszcz, Poland
| | - Andrzej Tretyn
- Faculty of Biological and Veterinary Sciences, Nicolaus Copernicus University, Toruń, Poland
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2
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Abohassan M, Al Shahrani M, Alshahrani MY, Begum N, Radhakrishnan S, Rajagopalan P. FNF-12, a novel benzylidene-chromanone derivative, attenuates inflammatory response in in vitro and in vivo asthma models mediated by M2-related Th2 cytokines via MAPK and NF-kB signaling. Pharmacol Rep 2021; 74:96-110. [PMID: 34468975 DOI: 10.1007/s43440-021-00325-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Revised: 08/02/2021] [Accepted: 08/23/2021] [Indexed: 01/13/2023]
Abstract
BACKGROUND AND AIM This study evaluates a novel benzylidene-chromanone derivative, FNF-12, for efficacy in in vitro and in vivo asthma models. METHODS Rat basophilic leukemia (RBL-2H3) and acute monocytic leukemia (THP-1)-derived M2 macrophages were used. Human whole blood-derived neutrophils and basophils were employed. Flow cytometry was used for studying key signalling proteins. Platelet activation factor (PAF)-induced asthma model in guinea pigs was used for in vivo studies. RESULTS The chemical structure of FNF-12 was confirmed with proton-nuclear mass resonance (NMR) and mass spectroscopy. FNF-12 controlled degranulation in RBL-2H3 cells with an IC50 value of 123.7 nM and inhibited TNF-α release from these cells in a dose-responsive way. The compound effectively controlled the migration and elastase release in activated neutrophils. IC50 value in the FcεRI-basophil activation assay was found to be 205 nM. FNF-12 controlled the release of lipopolysaccharide (LPS)-induced interleukin-10, I-309/CCL1 and MDC/CCL22 in THP-1 derived M2 macrophages. The compound suppressed LPS-induced mitogen activated protein kinase (MAPK)-p-p38 and nuclear factor kappa B(NF-kB)-p-p65 expression in these cells. A dose-dependent decrease in the accumulation of total leucocytes, eosinophils, neutrophils and macrophages was observed in PAF-induced animal models. CONCLUSION FNF-12 was able to control the inflammatory responses in in vitro and in vivo asthma models, which may be driven by controlling M2-related Th2 cytokines via MAPK and NF-kB signaling.
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Affiliation(s)
- Mohammad Abohassan
- Department of Clinical Laboratory Sciences, College of Applied Medical Sciences, King Khalid University, Abha, Saudi Arabia
| | - Mesfer Al Shahrani
- Department of Clinical Laboratory Sciences, College of Applied Medical Sciences, King Khalid University, Abha, Saudi Arabia
| | - Mohammad Y Alshahrani
- Department of Clinical Laboratory Sciences, College of Applied Medical Sciences, King Khalid University, Abha, Saudi Arabia
| | - Naseem Begum
- Department of Clinical Laboratory Sciences, College of Applied Medical Sciences, King Khalid University, Abha, Saudi Arabia
| | - Suresh Radhakrishnan
- Post Graduate and Research Department of Chemistry, Presidency College, Chennai, Tamil Nadu, India
| | - Prasanna Rajagopalan
- Department of Clinical Laboratory Sciences, College of Applied Medical Sciences, King Khalid University, Abha, Saudi Arabia.
- Central Research Laboratory, Department of Clinical Laboratory Sciences, College of Applied Medical Sciences, King Khalid University, Abha, Saudi Arabia.
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3
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Meng L, Zhen Z, Jiang Q, Li XH, Yuan Y, Yao W, Zhang MM, Li AJ, Shi L. Predictive model based on gene and laboratory data for intravenous immunoglobulin resistance in Kawasaki disease in a Chinese population. Pediatr Rheumatol Online J 2021; 19:95. [PMID: 34174887 PMCID: PMC8236184 DOI: 10.1186/s12969-021-00582-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Accepted: 04/04/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Here, we investigated the predictive efficiency of a newly developed model based on single nucleotide polymorphisms (SNPs) and laboratory data for intravenous immunoglobulin (IVIG) resistance in Kawasaki disease (KD) in a Chinese population. METHODS Data relating to children with KD were acquired from a single center between December 2015 and August 2019 and used to screen target SNPs. We then developed a predictive model of IVIG resistance using previous laboratory parameters. We then validated our model using data acquired from children with KD attending a second center between January and December 2019. RESULTS Analysis showed that rs10056474 GG, rs746994GG, rs76863441GT, rs16944 (CT/TT), and rs1143627 (CT/CC), increased the risk of IVIG-resistance in KD patients (odds ratio, OR > 1). The new predictive model, which combined SNP data with a previous model derived from laboratory data, significantly increased the area under the receiver-operator-characteristic curves (AUC) (0.832, 95% CI: 0.776-0.878 vs 0.793, 95%CI:0.734-0.844, P < 0.05) in the development dataset, and (0.820, 95% CI: 0.730-0.889 vs 0.749, 95% CI: 0.652-0.830, P < 0.05) in the validation dataset. The sensitivity and specificity of the new assay were 65.33% (95% CI: 53.5-76.0%) and 86.67% (95% CI: 80.2-91.7%) in the development dataset and 77.14% (95% CI: 59.9-89.6%) and 86.15% (95% CI: 75.3-93.5%) in the validation dataset. CONCLUSION Analysis showed that rs10056474 and rs746994 in the SMAD5 gene, rs76863441 in the PLA2G7 gene, and rs16944 or rs1143627 in the interleukin (IL)-1B gene, were associated with IVIG resistant KD in a Chinese population. The new model combined SNPs with laboratory data and improved the predictve efficiency of IVIG-resistant KD.
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Affiliation(s)
- Li Meng
- grid.418633.b0000 0004 1771 7032Capital Institute of Pediatrics-Peking University Teaching Hospital, Beijing, China ,grid.459434.bDepartment of Cardiology, Children’s Hospital Capital Institute of Pediatrics, No. 2 Ya-Bao Road, Chao Yang District, Beijing, 100020 China
| | - Zhen Zhen
- grid.24696.3f0000 0004 0369 153XDepartment of Cardiology, Beijing Children’s Hospital, Capital Medical University, National Center for Children’s Health, Beijing, China
| | - Qian Jiang
- grid.418633.b0000 0004 1771 7032Department of Genetics, Capital Institute of Pediatrics, Beijing, China
| | - Xiao-hui Li
- grid.418633.b0000 0004 1771 7032Capital Institute of Pediatrics-Peking University Teaching Hospital, Beijing, China ,grid.459434.bDepartment of Cardiology, Children’s Hospital Capital Institute of Pediatrics, No. 2 Ya-Bao Road, Chao Yang District, Beijing, 100020 China
| | - Yue Yuan
- grid.24696.3f0000 0004 0369 153XDepartment of Cardiology, Beijing Children’s Hospital, Capital Medical University, National Center for Children’s Health, Beijing, China
| | - Wei Yao
- grid.459434.bDepartment of Cardiology, Children’s Hospital Capital Institute of Pediatrics, No. 2 Ya-Bao Road, Chao Yang District, Beijing, 100020 China
| | - Ming-ming Zhang
- grid.459434.bDepartment of Cardiology, Children’s Hospital Capital Institute of Pediatrics, No. 2 Ya-Bao Road, Chao Yang District, Beijing, 100020 China
| | - Ai-jie Li
- grid.459434.bDepartment of Cardiology, Children’s Hospital Capital Institute of Pediatrics, No. 2 Ya-Bao Road, Chao Yang District, Beijing, 100020 China
| | - Lin Shi
- grid.459434.bDepartment of Cardiology, Children’s Hospital Capital Institute of Pediatrics, No. 2 Ya-Bao Road, Chao Yang District, Beijing, 100020 China
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4
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Sahu RP, Petrache I, Van Demark MJ, Rashid BM, Ocana JA, Tang Y, Yi Q, Turner MJ, Konger RL, Travers JB. Cigarette smoke exposure inhibits contact hypersensitivity via the generation of platelet-activating factor agonists. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2013; 190:2447-54. [PMID: 23355733 PMCID: PMC3577966 DOI: 10.4049/jimmunol.1202699] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Previous studies have established that pro-oxidative stressors suppress host immunity because of their ability to generate oxidized lipids with platelet-activating factor receptor (PAF-R) agonist activity. Although exposure to the pro-oxidative stressor cigarette smoke (CS) is known to exert immunomodulatory effects, little is known regarding the role of PAF in these events. The current studies sought to determine the role of PAF-R signaling in CS-mediated immunomodulatory effects. We demonstrate that CS exposure induces the generation of a transient PAF-R agonistic activity in the blood of mice. CS exposure inhibits contact hypersensitivity in a PAF-R-dependent manner as PAF-R-deficient mice were resistant to these effects. Blocking PAF-R agonist production either by systemic antioxidants or treatment with serum PAF-acetyl hydrolase enzyme blocked both the CS-mediated generation of PAF-R agonists and PAF-R-dependent inhibition of contact hypersensitivity (CHS) reactions, indicating a role for oxidized glycerophosphocholines with PAF-R agonistic activity in this process. In addition, cyclooxygenase-2 inhibition did not block PAF-R agonist production but prevented CS-induced inhibition of CHS. This suggests that cyclooxygenase-2 acts downstream of the PAF-R in mediating CS-induced systemic immunosuppression. Moreover, CS exposure induced a significant increase in the expression of the regulatory T cell reporter gene in Foxp3(EGFP) mice but not in Foxp3(EGFP) mice on a PAF-R-deficient background. Finally, regulatory T cell depletion via anti-CD25 Abs blocked CS-mediated inhibition of CHS, indicating the potential involvement of regulatory T cells in CS-mediated systemic immunosuppression. These studies provide the first evidence, to our knowledge, that the pro-oxidative stressor CS can modulate cutaneous immunity via the generation of PAF-R agonists produced through lipid oxidation.
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MESH Headings
- Animals
- Antioxidants/metabolism
- Cyclooxygenase 2/genetics
- Cyclooxygenase 2/metabolism
- Cyclooxygenase 2 Inhibitors/pharmacology
- Dermatitis, Contact/immunology
- Dermatitis, Contact/metabolism
- Dermatitis, Contact/pathology
- Dinitrofluorobenzene
- Female
- Forkhead Transcription Factors/genetics
- Forkhead Transcription Factors/metabolism
- Gene Expression/drug effects
- Glycerylphosphorylcholine/immunology
- Glycerylphosphorylcholine/metabolism
- Hydrolases/metabolism
- Immunosuppression Therapy
- Lipid Peroxidation/drug effects
- Lymphocyte Depletion
- Mice
- Mice, Transgenic
- Platelet Activating Factor/genetics
- Platelet Activating Factor/metabolism
- Platelet Membrane Glycoproteins/agonists
- Platelet Membrane Glycoproteins/genetics
- Platelet Membrane Glycoproteins/metabolism
- Receptors, G-Protein-Coupled/agonists
- Receptors, G-Protein-Coupled/genetics
- Receptors, G-Protein-Coupled/metabolism
- Signal Transduction/drug effects
- Smoke/adverse effects
- T-Lymphocytes, Regulatory/drug effects
- T-Lymphocytes, Regulatory/immunology
- T-Lymphocytes, Regulatory/pathology
- Nicotiana/adverse effects
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Affiliation(s)
- Ravi P Sahu
- Department of Dermatology, Herman B Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, IN 46202, USA
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5
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Li S, Stuart L, Zhang Y, Meduri GU, Umberger R, Yates CR. Inter-individual variability of plasma PAF-acetylhydrolase activity in ARDS patients and PAFAH genotype. J Clin Pharm Ther 2009; 34:447-55. [PMID: 19583678 DOI: 10.1111/j.1365-2710.2008.01014.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
BACKGROUND Platelet activating factor (PAF), a pro-inflammatory phospholipid, stimulates cytokine secretion from polymorphonuclear leukocytes expressing the transmembrane G-protein coupled PAF receptor. Elevated PAF levels are associated with acute respiratory distress syndrome (ARDS) and sepsis severity. The pro-inflammatory effects of PAF are terminated by PAF acetylhydrolase (PAF-AH). OBJECTIVE We sought to determine whether allelic variants in the human PAFAH gene (Arg92His, Ile198Thr, and Ala379Val) contribute to variability in PAF-AH activity in patient plasma obtained within 72 h of ARDS diagnosis. RESULTS Plasma PAF-AH activity (mean +/- SD) was higher in patients homozygous for the Arg92 allele compared to His92 allele carriers (2.21 +/- 0.77 vs. 1.64 +/- 0.68 U/min; P < 0.01; n = 31 and 21 respectively). Baseline plasma PAF-AH activity was higher among day 7 survivors vs. day 7 non-survivors (2.05 +/- 0.75 vs. 1.27 +/- 0.63, P = 0.05). CONCLUSION These data demonstrate an association between PAF-AH allelic variation, plasma activity, and outcome in ARDS.
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Affiliation(s)
- S Li
- Clinical Pharmacology, Quintiles, Inc., Overland Park, KS, USA
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6
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Stafforini DM. Biology of platelet-activating factor acetylhydrolase (PAF-AH, lipoprotein associated phospholipase A2). Cardiovasc Drugs Ther 2008; 23:73-83. [PMID: 18949548 DOI: 10.1007/s10557-008-6133-8] [Citation(s) in RCA: 161] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/31/2008] [Accepted: 08/06/2008] [Indexed: 12/26/2022]
Abstract
INTRODUCTION This article is focused on platelet-activating factor acetylhydrolase (PAF-AH), a lipoprotein bound, calcium-independent phospholipase A(2) activity also referred to as lipoprotein-associated phospholipase A(2) or PLA(2)G7. PAF-AH catalyzes the removal of the acyl group at the sn-2 position of PAF and truncated phospholipids generated in settings of inflammation and oxidant stress. DISCUSSION Here, I discuss current knowledge related to the structural features of this enzyme, including the molecular basis for association with lipoproteins and susceptibility to oxidative inactivation. The circulating form of PAF-AH is constitutively active and its expression is upregulated by mediators of inflammation at the transcriptional level. This mechanism is likely responsible for the observed up-regulation of PAF-AH during atherosclerosis and suggests that increased expression of this enzyme is a physiological response to inflammatory stimuli. Administration of recombinant forms of PAF-AH attenuate inflammation in a variety of experimental models. Conversely, genetic deficiency of PAF-AH in defined human populations increases the severity of atherosclerosis and other syndromes. Recent advances pointing to an interplay among oxidized phospholipid substrates, Lp(a), and PAF-AH could hold the key to a number of unanswered questions.
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Affiliation(s)
- Diana M Stafforini
- Huntsman Cancer Institute and Department of Internal Medicine, University of Utah, 2000 Circle of Hope, Suite 3364, Salt Lake City, UT 84112-5550, USA.
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7
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Gardner AA, Reichert EC, Topham MK, Stafforini DM. Identification of a domain that mediates association of platelet-activating factor acetylhydrolase with high density lipoprotein. J Biol Chem 2008; 283:17099-106. [PMID: 18434304 DOI: 10.1074/jbc.m802394200] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The plasma form of platelet-activating factor (PAF) acetylhydrolase (PAF-AH), also known as lipoprotein-associated phospholipase A(2) (Lp-PLA(2)) inactivates potent lipid messengers such as PAF and modified phospholipids generated in settings of oxidant stress. In humans, PAF-AH circulates in blood in fully active form and associates with high and low density lipoproteins (HDL and LDL). Several studies suggest that the location of PAF-AH affects both the catalytic efficiency and the function of the enzyme in vivo. The distribution of PAF-AH among lipoproteins varies widely among mammals. Here, we report that mouse and human PAF-AHs associate with human HDL particles of different density. We made use of this observation in the development of a binding assay to identify domains required for association of human PAF-AH with human HDL. Sequence comparisons among species combined with domain-swapping and site-directed mutagenesis studies led us to the identification of C-terminal residues necessary for the association of human PAF-AH with human HDL. Interestingly, the region identified is not conserved among PAF-AHs, suggesting that PAF-AH interacts with HDL particles in a manner that is unique to each species. These findings contribute to our understanding of the mechanisms responsible for association of human PAF-AH with HDL and may facilitate future studies aimed at precisely determining the function of PAF-AH in each lipoprotein particle.
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Affiliation(s)
- Alison A Gardner
- Huntsman Cancer Institute and Department of Internal Medicine, University of Utah, Salt Lake City, Utah 84112, USA
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8
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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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9
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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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10
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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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Zimmerman GA, McIntyre TM. PAF, ceramide and pulmonary edema: alveolar flooding and a flood of questions. Trends Mol Med 2004; 10:245-8. [PMID: 15177186 DOI: 10.1016/j.molmed.2004.03.009] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Guy A Zimmerman
- Department of Internal Medicine, University of Utah School of Medicine, Salt Lake City, UT 84112, USA.
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12
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Stafforini DM, McIntyre TM, Zimmerman GA, Prescott SM. Platelet-activating factor, a pleiotrophic mediator of physiological and pathological processes. Crit Rev Clin Lab Sci 2004; 40:643-72. [PMID: 14708958 DOI: 10.1080/714037693] [Citation(s) in RCA: 155] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Platelet-activating factor (PAF) is a potent proinflammatory phospholipid with diverse pathological and physiological effects. This bioactive phospholipid mediates processes as diverse as wound healing, physiological inflammation, apoptosis, angiogenesis, reproduction and long-term potentiation. Recent progress has demonstrated the participation of MAP kinase signaling pathways as modulators of the two critical enzymes, phospholipase A2 and acetyltransferase, involved in the remodeling pathway of PAF biosynthesis. The unregulated production of structural analogs of PAF by non-specific oxidative reactions has expanded this superfamily of signaling molecules to include "PAF-like" lipids whose mode of action is identical to that of authentic PAF. The action of members of this family is mediated by the PAF receptor, a G protein-coupled membrane-spanning molecule that can engage multiple signaling pathways in various cell types. Inappropriate activation of this signaling pathway is associated with many diseases in which inflammation is thought to be one of the underlying features. Inactivation of all members of the PAF superfamily occurs by a unique class of enzymes, the PAF acetylhydrolases, that have been characterized at the molecular level and that terminate signals initiated by both regulated and unregulated PAF production.
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Affiliation(s)
- Diana M Stafforini
- Huntsman Cancer Institute, University of Utah, Salt Lake City, Utah 84112-5550, USA.
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13
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Abstract
In canine renal tubular cells, the effect of Y-24180, a presumed specific platelet activating factor (PAF) receptor antagonist, on intracellular Ca(2+) concentration ([Ca(2+)](i)) was measured by using fura-2 as a Ca(2+)-sensitive fluorescent probe. Y-24180 (0.1-10 microM) caused a rapid and sustained [Ca(2+)](i) rise in a concentration-dependent manner. The [Ca(2+)](i) rise was prevented by 30% by removal of extracellular Ca(2+), but was not changed by dihydropyridines, verapamil and diltiazem. Y-24180-induced Ca(2+) influx was confirmed by Mn(2+)-influx induced quench of fura-2 fluorescence. In Ca(2+)-free medium, thapsigargin, an inhibitor of the endoplasmic reticulum Ca(2+)-ATPase, caused a monophasic [Ca(2+)](i) rise, after which the increasing effect of 5 microM Y-24180 on [Ca(2+)](i) was abolished; conversely, depletion of Ca(2+) stores with 5 microM Y-24180 abolished thapsigargin-induced [Ca(2+)](i) rise. U73122, an inhibitor of phoispholipase C, inhibited ATP-, but not Y-24180-induced [Ca(2+)](i) rise. Overnight treatment with Y-24180 did not alter cell proliferation rate. Collectively, these results suggest that Y-24180 acts as a potent, but not cytotoxic, Ca(2+) mobilizer in renal tubular cells, by stimulating both extracellular Ca(2+) influx and intracellular Ca(2+) release. Since alterations in Ca(2+) movement may interfere many cellular signaling processes unrelated to modulation of PAF receptors, caution must be applied in using this chemical as a selective PAF receptor antagonist.
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Affiliation(s)
- Yu-Ying Chao
- School of Public Health, Kaohsiung Medical University, Kaohsiung, Taiwan
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14
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Kujiraoka T, Iwasaki T, Ishihara M, Ito M, Nagano M, Kawaguchi A, Takahashi S, Ishi J, Tsuji M, Egashira T, Stepanova IP, Miller NE, Hattori H. Altered distribution of plasma PAF-AH between HDLs and other lipoproteins in hyperlipidemia and diabetes mellitus. J Lipid Res 2003; 44:2006-14. [PMID: 12867534 DOI: 10.1194/jlr.d300021-jlr200] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Platelet-activating factor acetylhydrolase (PAF-AH) is a phospholipase A2 associated with lipoproteins that hydrolyzes platelet-activating factor (PAF) and oxidized phospholipids. We have developed an ELISA for PAF-AH that is more sensitive than previous methods, and have quantified HDL-associated and non-HDL-associated PAF-AH in healthy, hyperlipidemic, and diabetic subjects. In healthy subjects, plasma total PAF-AH concentration was positively correlated with PAF-AH activity and with plasma total cholesterol, triacylglycerol, LDL cholesterol and apolipoprotein B (apoB) concentrations (all P < 0.01). HDL-associated PAF-AH concentration was correlated positively with plasma apoA-I and HDL cholesterol. Subjects with hyperlipidemia (n = 73) and diabetes mellitus (n = 87) had higher HDL-associated PAF-AH concentrations than did controls (P < 0.01). Non-HDL-associated PAF-AH concentration was lower in diabetic subjects than in controls (P < 0.01). Both hyperlipidemic and diabetic subjects had lower ratios of PAF-AH to apoB (P < 0.01) and higher ratios of PAF-AH to apoA-I (P < 0.01) than did controls. Our results show that the distribution of PAF-AH mass between HDLs and LDLs is determined partly by the concentrations of the lipoproteins and partly by the mass of enzyme per lipoprotein particle, which is disturbed in hyperlipidemia and diabetes mellitus.
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Affiliation(s)
- Takeshi Kujiraoka
- Department of Advanced Medical Technology and Development, BML, Inc., Saitama, Japan
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Abstract
Current asthma therapy is directed at the relief of chronic inflammation or improving lung function through bronchodilation. These approaches treat the overt symptoms of asthma but do not approach underlying causes of the disease. Such therapies have limited efficacy and for a number of patients the disease remains poorly controlled. The short-term future of asthma therapy will probably focus on the treatment of multiple symptoms to provide improved lung function. Long-term approaches to asthma will have to focus on modulation of the mechanisms that are the underlying causes of the various asthmatic pathophysiologies. These targets include a number of TH2-type T-cell-generated cytokines and chemokines, G-protein-coupled receptors, TH2-related transcription factors, neurotrophins and adhesion molecules. Additional new targets and understanding of asthma may also arise from genetic analysis.
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Affiliation(s)
- Scott Greenfeder
- Department of Allergy, Schering-Plough Research Institute, 2015 Galloping Hill Road, MS-1600, Kenilworth, NJ 07033, USA.
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Zimmerman GA, McIntyre TM, Prescott SM, Stafforini DM. The platelet-activating factor signaling system and its regulators in syndromes of inflammation and thrombosis. Crit Care Med 2002; 30:S294-301. [PMID: 12004251 DOI: 10.1097/00003246-200205001-00020] [Citation(s) in RCA: 257] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
OBJECTIVES To review the platelet-activating factor (PAF) signaling system, its regulation, and its dysregulation in acute inflammation and thrombosis and in syndromes that involve these cascades, including sepsis. DATA SOURCES A summary of published literature from MEDLINE search files and published reviews. DATA EXTRACTION, SYNTHESIS, AND SUMMARY: PAF, a phospholipid signaling molecule, transmits outside-in signals to intracellular transduction systems and effector mechanisms in a variety of cell types, including key cells of the innate immune and hemostatic systems: neutrophils, monocytes, and platelets. Thus, the PAF signaling system is a point of convergence at which injurious stimuli can trigger and amplify both acute inflammatory and thrombotic cascades. The biological activities of PAF are regulated by several precise mechanisms that, together, constrain and control its action in physiologic inflammation. Unregulated synthesis of PAF or defects in the mechanisms that limit its biological activities have the potential to cause pathologic inflammation and thrombosis. In addition, nonenzymatic generation of oxidized phospholipids that are recognized by the PAF receptor can trigger inflammatory and thrombotic events. There is evidence that the PAF signaling system is dysregulated in sepsis, shock, and traumatic injury and that interruption or termination of its effector responses leads to beneficial outcomes. Plasma PAF acetylhydrolase, an enzyme that hydrolyzes PAF and structurally related oxidized phospholipids, yielding products that are no longer recognized by the PAF receptor, may be a particularly important signal terminator. CONCLUSION The PAF signaling system can trigger inflammatory and thrombotic cascades, amplify these cascades when acting with other mediators, and mediate molecular and cellular interactions (cross talk) between inflammation and thrombosis. Evidence from in vitro experiments, studies of experimental animals, and clinical observations in humans indicates that the PAF signaling system is important in sepsis and other syndromes of inflammatory injury and that therapeutic strategies to interrupt or terminate signaling via the PAF signaling system may be useful in these conditions.
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Affiliation(s)
- Guy A Zimmerman
- Program in Human Molecular Biology and Genetics, University of Utah, Salt Lake City, UT 84112, USA.
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Prescott SM, McIntyre TM, Zimmerman GA, Stafforini DM. Sol Sherry lecture in thrombosis: molecular events in acute inflammation. Arterioscler Thromb Vasc Biol 2002; 22:727-33. [PMID: 12006383 DOI: 10.1161/01.atv.0000016153.47693.b2] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The inflammatory response is characterized by a multistep molecular interaction between "signaling" cells, such as endothelial cells, and "responding" cells, such as neutrophils and monocytes. In the first step, selectins produced by signaling cells mediate the tethering of responding cells at sites of inflammation. Subsequently, an additional mediator expressed by signaling cells activates the tethered responding cells. Under pathological conditions, the same mechanism is invoked in inappropriate ways: (1) by prolonged presentation of selectins on the cell surface and (2) by the unregulated production of oxidized phospholipids that mimic the normal secondary signaling molecule, platelet-activating factor (PAF). The enzyme PAF acetylhydrolase (PAF-AH) inactivates PAF and oxidized phospholipids and constitutes an "off" switch that suppresses inflammation. Inhibition of normal PAF-AH function or inactivating mutations of the PAF-AH gene can lead to increased susceptibility to inflammatory disease. These studies have relevance to atherosclerosis and thrombosis, because inflammation is a central feature of both.
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Affiliation(s)
- Stephen M Prescott
- Huntsman Cancer Institute, University of Utah, Salt Lake City 84112, USA.
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