1
|
Manson A, Winter T, Aukema HM. Phospholipase A 2 enzymes differently impact PUFA release and oxylipin formation ex vivo in rat hearts. Prostaglandins Leukot Essent Fatty Acids 2023; 191:102555. [PMID: 36878084 DOI: 10.1016/j.plefa.2023.102555] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/29/2022] [Revised: 02/16/2023] [Accepted: 02/23/2023] [Indexed: 03/04/2023]
Abstract
Phospholipase A2 (PLA2) enzymes cleave cell membrane phospholipids and release polyunsaturated fatty acids (PUFA), which can be converted into oxylipins. However, little is known about PLA2 preference for PUFA, and even less is known about how this further impacts oxylipin formation. Therefore, we investigated the role of different PLA2 groups in PUFA release and oxylipin formation in rat hearts. Sprague-Dawley rat heart homogenates were incubated without or with varespladib (VAR), methyl arachidonyl fluorophosphonate (MAFP) or EDTA. Free PUFA and oxylipins were determined by HPLC-MS/MS, and isoform expressions by RT-qPCR. Inhibition of sPLA2 IIA and/or V by VAR reduced the release of ARA and DHA, but only DHA oxylipins were inhibited. MAFP reduced the release of ARA, DHA, ALA, and EPA, and the formation of ARA, LA, DGLA, DHA, ALA, and EPA oxylipins. Interestingly, cyclooxygenase and 12-lipoxygenase oxylipins were not inhibited. mRNA expression levels of sPLA2 and iPLA2 isoforms were highest whereas levels of cPLA2 were low, consistent with activity. In conclusion, sPLA2 enzymes lead to the formation of DHA oxylipins, while iPLA2 is likely responsible for the formation of most other oxylipins in healthy rat hearts. Oxylipin formation cannot be implied from PUFA release, thus, both should be evaluated in PLA2 activity studies.
Collapse
Affiliation(s)
- Anne Manson
- Food and Human Nutritional Sciences, University of Manitoba, Winnipeg MB, Canada; Canadian Centre for Agri-Food Research in Health and Medicine (CCARM), Winnipeg MB, Canada
| | - Tanja Winter
- Food and Human Nutritional Sciences, University of Manitoba, Winnipeg MB, Canada; Canadian Centre for Agri-Food Research in Health and Medicine (CCARM), Winnipeg MB, Canada
| | - Harold M Aukema
- Food and Human Nutritional Sciences, University of Manitoba, Winnipeg MB, Canada; Canadian Centre for Agri-Food Research in Health and Medicine (CCARM), Winnipeg MB, Canada.
| |
Collapse
|
2
|
Ravindran R, PK PK, Kumar S, Roy S, Gowthaman SA, Rajkumar J. Computational Study Reveals PARP1 and P2Y1 Receptors as Prospective Targets of Withaferin-A for Cardiovascular Diseases. LETT DRUG DES DISCOV 2021. [DOI: 10.2174/1570180819666211228103102] [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:
Cardiovascular Diseases (CVDs) remain the leading cause of death worldwide, which urges for effective strategies of prevention and treatment. Withaferin-A (WFA), the key metabolite identified in Withania somnifera, has been known for its cardioprotective properties. Although it has been traditionally employed to treat cardiovascular ailments for several decades, its exact mechanism of action still remains unexplained
Objective:
The current study modelled and scored the interactions of WFA with nine prospective protein-targets associated with cardiovascular diseases through molecular docking and DSX-scoring.
Methods:
Molecular docking was carried out using Autodock and DSX-scoring was carried out using DSX standalone software. WFA was observed to favorably interact with six targets before DSX-based rescoring, but only with Poly (ADP-Ribose) Polymerase-1 and P2Y Purinoceptor-1 after DSX-based rescoring. The spatial orientation, physicochemical properties and structural features of Withaferin-A were compared with that of these approved drugs by pharmacophore modeling and hierarchical clustering
Results:
The results of molecular docking, DSX-based rescoring and complete pharmacophore modeling together revealed that PARP1 and P2Y1 receptor could be prospective targets of WFA for the treatment of CVD.
Conclusion:
Simulation using GROMACS has revealed that WFA forms a more stable complex with PARP1 and will be useful in developing the broad-spectrum drugs against cardiovascular diseases. Further computational studies through machine learning and network pharmacology methods can be carried out to improve Withaferin-A compound features by incorporating additional functional groups necessary for molecular recognition of the target genes in network responsible for cardiovascular diseases.
Collapse
Affiliation(s)
- Rekha Ravindran
- Department of Biotechnology, Rajalakshmi Engineering College, Rajalakshmi Nagar, Thandalam, Chennai-602105, Tamil Nadu, India
| | - Praveen Kumar PK
- Department of Biotechnology, Sri Venkateswara College of Engineering, Sriperumbudur Tk – 602117, Tamil Nadu, India
| | - Sriram Kumar
- Department of Biotechnology, Rajalakshmi Engineering College, Rajalakshmi Nagar, Thandalam, Chennai-602105, Tamil Nadu, India
| | - Sujata Roy
- Department of Biotechnology, Rajalakshmi Engineering College, Rajalakshmi Nagar, Thandalam, Chennai-602105, Tamil Nadu, India
| | - Sakthi Abirami Gowthaman
- Department of Biotechnology, Rajalakshmi Engineering College, Rajalakshmi Nagar, Thandalam, Chennai-602105, Tamil Nadu, India
| | - Johanna Rajkumar
- Department of Biotechnology, Rajalakshmi Engineering College, Rajalakshmi Nagar, Thandalam, Chennai-602105, Tamil Nadu, India
| |
Collapse
|
3
|
Yamamoto Y, Sugimura R, Watanabe T, Shigemori S, Okajima T, Nigar S, Namai F, Sato T, Ogita T, Shimosato T. Class A CpG Oligonucleotide Priming Rescues Mice from Septic Shock via Activation of Platelet-Activating Factor Acetylhydrolase. Front Immunol 2017; 8:1049. [PMID: 28912777 PMCID: PMC5582170 DOI: 10.3389/fimmu.2017.01049] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2017] [Accepted: 08/14/2017] [Indexed: 01/10/2023] Open
Abstract
Sepsis is a life-threatening, overwhelming immune response to infection with high morbidity and mortality. Inflammatory response and blood clotting are caused by sepsis, which induces serious organ damage and death from shock. As a mechanism of pathogenesis, platelet-activating factor (PAF) induces excessive inflammatory responses and blood clotting. In this study, we demonstrate that a Class A CpG oligodeoxynucleotide (CpG-A1585) strongly induced PAF acetylhydrolase, which generates lyso-PAF. CpG-A1585 rescued mice from acute lethal shock and decreased fibrin deposition, a hallmark of PAF-induced disseminated intravascular coagulation. Furthermore, CpG-A1585 improved endotoxin shock induced by lipopolysaccharide, which comprises the cell wall of Gram-negative bacteria and inhibits inflammatory responses induced by cytokines such as interleukin-6 and tumor necrosis factor-α. These results suggest that CpG-A1585 is a potential therapeutic target to prevent sepsis-related induction of PAF.
Collapse
Affiliation(s)
- Yoshinari Yamamoto
- Department of Bioscience and Food Production Science, Interdisciplinary Graduate School of Science and Technology, Shinshu University, Nagano, Japan.,Research Fellow of the Japan Society for the Promotion of Science, Japan Society for the Promotion of Science, Tokyo, Japan
| | - Ryu Sugimura
- Department of Agricultural and Life Science, Graduate School of Science and Technology, Shinshu University, Nagano, Japan
| | - Takafumi Watanabe
- Department of Agricultural and Life Science, Graduate School of Science and Technology, Shinshu University, Nagano, Japan
| | - Suguru Shigemori
- Faculty of Medicine, Department of Intestinal Ecosystem Regulation, University of Tsukuba, Ibaraki, Japan.,Metabologenomics Core, Transborder Medical Research Center, University of Tsukuba, Ibaraki, Japan
| | - Takuma Okajima
- Department of Agricultural and Life Science, Graduate School of Science and Technology, Shinshu University, Nagano, Japan
| | - Shireen Nigar
- Department of Bioscience and Food Production Science, Interdisciplinary Graduate School of Science and Technology, Shinshu University, Nagano, Japan.,Department of Nutrition and Food Technology, Jessore University of Science and Technology, Jessore, Bangladesh
| | - Fu Namai
- Department of Agricultural and Life Science, Graduate School of Science and Technology, Shinshu University, Nagano, Japan
| | - Takashi Sato
- Department of Pulmonology, Graduate School of Medicine, Yokohama City University, Kanagawa, Japan
| | - Tasuku Ogita
- Department of Interdisciplinary Genome Sciences and Cell Metabolism, Institute for Biomedical Sciences, Shinshu University, Nagano, Japan
| | - Takeshi Shimosato
- Department of Interdisciplinary Genome Sciences and Cell Metabolism, Institute for Biomedical Sciences, Shinshu University, Nagano, Japan.,Department of Supramolecular Complexes, Research Center for Fungal and Microbial Dynamism, Shinshu University, Nagano, Japan
| |
Collapse
|
4
|
Wu H, Bogdanov M, Zhang Y, Sun K, Zhao S, Song A, Luo R, Parchim NF, Liu H, Huang A, Adebiyi MG, Jin J, Alexander DC, Milburn MV, Idowu M, Juneja HS, Kellems RE, Dowhan W, Xia Y. Hypoxia-mediated impaired erythrocyte Lands' Cycle is pathogenic for sickle cell disease. Sci Rep 2016; 6:29637. [PMID: 27436223 PMCID: PMC4951653 DOI: 10.1038/srep29637] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Accepted: 06/17/2016] [Indexed: 02/08/2023] Open
Abstract
Although Lands' cycle was discovered in 1958, its function and cellular regulation in membrane homeostasis under physiological and pathological conditions remain largely unknown. Nonbiased high throughput metabolomic profiling revealed that Lands' cycle was impaired leading to significantly elevated erythrocyte membrane lysophosphatidylcholine (LysoPC) content and circulating and erythrocyte arachidonic acid (AA) in mice with sickle cell disease (SCD), a prevalent hemolytic genetic disorder. Correcting imbalanced Lands' cycle by knockdown of phospholipase 2 (cPLA2) or overexpression of lysophosphatidycholine acyltransferase 1 (LPCAT1), two key enzymes of Lands' cycle in hematopoietic stem cells, reduced elevated erythrocyte membrane LysoPC content and circulating AA levels and attenuated sickling, inflammation and tissue damage in SCD chimeras. Human translational studies validated SCD mouse findings and further demonstrated that imbalanced Lands' cycle induced LysoPC production directly promotes sickling in cultured mouse and human SCD erythrocytes. Mechanistically, we revealed that hypoxia-mediated ERK activation underlies imbalanced Lands' cycle by preferentially inducing the activity of PLA2 but not LPCAT in human and mouse SCD erythrocytes. Overall, our studies have identified a pathological role of imbalanced Lands' cycle in SCD erythrocytes, novel molecular basis regulating Lands' cycle and therapeutic opportunities for the disease.
Collapse
Affiliation(s)
- Hongyu Wu
- Department of Biochemistry and Molecular Biology, University of Texas-Medical School, Houston, TX, USA
| | - Mikhail Bogdanov
- Department of Biochemistry and Molecular Biology, University of Texas-Medical School, Houston, TX, USA
| | - Yujin Zhang
- Department of Biochemistry and Molecular Biology, University of Texas-Medical School, Houston, TX, USA
| | - Kaiqi Sun
- Department of Biochemistry and Molecular Biology, University of Texas-Medical School, Houston, TX, USA.,Graduate School of Biomedical Science, University of Texas, Houston, TX, USA
| | - Shushan Zhao
- Department of Biochemistry and Molecular Biology, University of Texas-Medical School, Houston, TX, USA
| | - Anren Song
- Department of Biochemistry and Molecular Biology, University of Texas-Medical School, Houston, TX, USA
| | - Renna Luo
- Department of Biochemistry and Molecular Biology, University of Texas-Medical School, Houston, TX, USA
| | - Nicholas F Parchim
- Department of Biochemistry and Molecular Biology, University of Texas-Medical School, Houston, TX, USA.,Graduate School of Biomedical Science, University of Texas, Houston, TX, USA
| | - Hong Liu
- Department of Biochemistry and Molecular Biology, University of Texas-Medical School, Houston, TX, USA.,Graduate School of Biomedical Science, University of Texas, Houston, TX, USA
| | - Aji Huang
- Department of Biochemistry and Molecular Biology, University of Texas-Medical School, Houston, TX, USA
| | - Morayo G Adebiyi
- Department of Biochemistry and Molecular Biology, University of Texas-Medical School, Houston, TX, USA.,Graduate School of Biomedical Science, University of Texas, Houston, TX, USA
| | - Jianping Jin
- Department of Biochemistry and Molecular Biology, University of Texas-Medical School, Houston, TX, USA
| | | | | | - Modupe Idowu
- Department of Internal Medicine, University of Texas-Medical School, Houston, TX, USA
| | - Harinder S Juneja
- Department of Internal Medicine, University of Texas-Medical School, Houston, TX, USA
| | - Rodney E Kellems
- Department of Biochemistry and Molecular Biology, University of Texas-Medical School, Houston, TX, USA.,Graduate School of Biomedical Science, University of Texas, Houston, TX, USA
| | - William Dowhan
- Department of Biochemistry and Molecular Biology, University of Texas-Medical School, Houston, TX, USA
| | - Yang Xia
- Department of Biochemistry and Molecular Biology, University of Texas-Medical School, Houston, TX, USA.,Graduate School of Biomedical Science, University of Texas, Houston, TX, USA
| |
Collapse
|
5
|
Giri S, Jennings LK. The Spectrum of Thrombin in Acute Coronary Syndromes. Thromb Res 2015; 135:782-7. [DOI: 10.1016/j.thromres.2015.02.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2014] [Revised: 02/06/2015] [Accepted: 02/10/2015] [Indexed: 12/25/2022]
|
6
|
Kispert SE, Marentette JO, McHowat J. Enhanced breast cancer cell adherence to the lung endothelium via PAF acetylhydrolase inhibition: a potential mechanism for enhanced metastasis in smokers. Am J Physiol Cell Physiol 2014; 307:C951-6. [PMID: 25186013 DOI: 10.1152/ajpcell.00218.2014] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Cancer deaths are primarily caused by distant metastases, rather than by primary tumor growth; however, the role of smoking in metastasis remains unclear. We demonstrated previously that endothelial cell platelet-activating factor (PAF) production results in enhanced inflammatory cell recruitment to the lung. We propose that endothelial cell PAF accumulation plays a role in cancer cell migration to distal locations. We used cigarette smoke extract (CSE) to inhibit the activity of endothelial cell PAF acetylhydrolase (PAF-AH), which hydrolyzes and inactivates PAF, and determined whether this results in increased endothelial cell PAF accumulation and breast cancer adherence. Incubation of human lung microvascular endothelial cells (HMVEC-L) with CSE resulted in a significant inhibition of PAF-AH activity that was accompanied by increased PAF production and adherence of highly invasive MDA-MB-231 breast cancer cells. Pretreatment of HMVEC-L with (S)-bromoenol lactone to inhibit calcium-independent phospholipase A2β (iPLA2β, which initiates endothelial cell PAF production) prior to CSE exposure resulted in complete inhibition of MDA-MB-231 cell adherence. Similarly, pretreatment of MDA-MB-231 cells with the PAF receptor antagonist Ginkgo biloba resulted in inhibition of adherence to the endothelium. Immunoblot analysis indicated an increase in MDA-MB-231 cell PAF receptor expression with CSE exposure. Taken together, our data indicate that CSE exposure increases endothelial cell PAF production, resulting in enhanced adherence of tumor cells to the endothelium. Our in vitro data indicate that increased tumor cell adherence would lead to enhanced metastasis formation in smokers. Potential therapeutic targets include endothelial cell iPLA2β or the tumor cell PAF receptor.
Collapse
Affiliation(s)
- Shannon E Kispert
- Department of Pathology, Saint Louis University School of Medicine, St. Louis, Missouri
| | - John O Marentette
- Department of Pathology, Saint Louis University School of Medicine, St. Louis, Missouri
| | - Jane McHowat
- Department of Pathology, Saint Louis University School of Medicine, St. Louis, Missouri
| |
Collapse
|
7
|
Wu H, Yang J, Su EM, Li L, Zhao C, Yang X, Gao Z, Pan M, Sun P, Sun W, Jiang Y, Su X. Lipoxin A4 and platelet activating factor are involved in E. coli or LPS-induced lung inflammation in CFTR-deficient mice. PLoS One 2014; 9:e93003. [PMID: 24671173 PMCID: PMC3966846 DOI: 10.1371/journal.pone.0093003] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2014] [Accepted: 02/28/2014] [Indexed: 01/03/2023] Open
Abstract
CFTR (cystic fibrosis transmembrane conductance regulator) is expressed by both neutrophils and platelets. Lack of functional CFTR could lead to severe lung infection and inflammation. Here, we found that mutation of CFTR (F508del) or inhibition of CFTR in mice led to more severe thrombocytopenia, alveolar neutrocytosis and bacteriosis, and lower lipoxin A4/MIP-2 (macrophage inhibitory protein-2) or lipoxin A4/neutrophil ratios in the BAL (bronchoalveolar lavage) during acute E. coli pneumonia. In vitro, inhibition of CFTR promotes MIP-2 production in LPS-stimulated neutrophils; however, lipoxin A4 could dose-dependently suppress this effect. In LPS-induced acute lung inflammation, blockade of PSGL-1 (P-selectin glycoprotein ligand-1) or P-selectin, antagonism of PAF by WEB2086, or correction of mutated CFTR trafficking by KM11060 could significantly increase plasma lipoxin A4 levels in F508del relevant to wildtype mice. Concurrently, F508del mice had higher plasma platelet activating factor (PAF) levels and PAF-AH activity compared to wildtype under LPS challenge. Inhibiting hydrolysis of PAF by a specific PAF-AH (PAF-acetylhydrolase) inhibitor, MAFP, could worsen LPS-induced lung inflammation in F508del mice compared to vehicle treated F508del group. Particularly, depletion of platelets in F508del mice could significantly decrease plasma lipoxin A4 and PAF-AH activity and deteriorate LPS-induced lung inflammation compared to control F508del mice. Taken together, lipoxin A4 and PAF are involved in E. coli or LPS-induced lung inflammation in CFTR-deficient mice, suggesting that lipoxin A4 and PAF might be therapeutic targets for ameliorating CFTR-deficiency deteriorated lung inflammation.
Collapse
Affiliation(s)
- Haiya Wu
- Key Laboratory of Molecular Virology & Immunology, Unit of Respiratory Infection and Immunity, Institut Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai, China
| | - Jun Yang
- Department of Entomology, University of California Davis, Davis, California, United States of America
| | - Emily M. Su
- Cardiovascular Research Institute, University of California San Francisco, San Francisco, California, United States of America
| | - Ling Li
- Key Laboratory of Molecular Virology & Immunology, Unit of Respiratory Infection and Immunity, Institut Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai, China
| | - Caiqi Zhao
- Key Laboratory of Molecular Virology & Immunology, Unit of Respiratory Infection and Immunity, Institut Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai, China
| | - Xi Yang
- Key Laboratory of Molecular Virology & Immunology, Unit of Respiratory Infection and Immunity, Institut Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai, China
| | - Zhaowei Gao
- Key Laboratory of Molecular Virology & Immunology, Unit of Respiratory Infection and Immunity, Institut Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai, China
| | - Mengyao Pan
- Key Laboratory of Molecular Virology & Immunology, Unit of Respiratory Infection and Immunity, Institut Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai, China
| | - Peiyu Sun
- Key Laboratory of Molecular Virology & Immunology, Unit of Respiratory Infection and Immunity, Institut Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai, China
| | - Wei Sun
- Key Laboratory of Molecular Virology & Immunology, Unit of Respiratory Infection and Immunity, Institut Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai, China
| | - Yiyi Jiang
- Key Laboratory of Molecular Virology & Immunology, Unit of Respiratory Infection and Immunity, Institut Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai, China
| | - Xiao Su
- Key Laboratory of Molecular Virology & Immunology, Unit of Respiratory Infection and Immunity, Institut Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai, China
- Cardiovascular Research Institute, University of California San Francisco, San Francisco, California, United States of America
- * E-mail:
| |
Collapse
|
8
|
Fitzgerald C, Gallagher E, O'Connor P, Prieto J, Mora-Soler L, Grealy M, Hayes M. Development of a seaweed derived platelet activating factor acetylhydrolase (PAF-AH) inhibitory hydrolysate, synthesis of inhibitory peptides and assessment of their toxicity using the Zebrafish larvae assay. Peptides 2013; 50:119-24. [PMID: 24140404 DOI: 10.1016/j.peptides.2013.10.006] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/13/2013] [Revised: 10/07/2013] [Accepted: 10/07/2013] [Indexed: 01/24/2023]
Abstract
The vascular inflammatory role of platelet activating factor acetylhydrolase (PAF-AH) is thought to be due to the formation of lysophosphatidyl choline and oxidized non-esterified fatty acids. This enzyme is considered a promising therapeutic target for the prevention of atherosclerosis and there is a need to expand the available chemical templates of PAF-AH inhibitors. This study demonstrated how natural PAF-AH inhibitory peptides were isolated and characterized from the red macroalga Palmaria palmata. The dried powdered alga was hydrolyzed using the food grade enzyme papain, and the resultant peptide containing fraction generated using RP-HPLC. Several oligopeptides were identified as potential PAF-AH inhibitors following bio-guided fractionation, and the amino acid sequences of these oligopeptides were confirmed by Q-TOF-MS and microwave-assisted solid phase de novo synthesis. The most promising PAF-AH inhibitory peptide had the amino acid sequence NIGK and a PAF-AH IC50 value of 2.32 mM. This peptide may constitute a valid drug template for PAF-AH inhibitors. Furthermore the P. palmata hydrolysate was nontoxic when assayed using the Zebrafish toxicity model at a concentration of 1mg/ml.
Collapse
Affiliation(s)
- Ciarán Fitzgerald
- Food Biosciences Department, Teagasc Food Research Centre, Ashtown, Dublin 15, Ireland.
| | | | | | | | | | | | | |
Collapse
|
9
|
Sharma J, Young DM, Marentette JO, Rastogi P, Turk J, McHowat J. Lung endothelial cell platelet-activating factor production and inflammatory cell adherence are increased in response to cigarette smoke component exposure. Am J Physiol Lung Cell Mol Physiol 2012; 302:L47-55. [PMID: 21984569 PMCID: PMC3349370 DOI: 10.1152/ajplung.00179.2011] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2011] [Accepted: 10/03/2011] [Indexed: 12/30/2022] Open
Abstract
An early event in the pathogenesis of emphysema is the development of inflammation associated with accumulation of polymorphonuclear leukocytes (PMN) in small airways, and inflammatory cell recruitment from the circulation involves migration across endothelial and epithelial cell barriers. Platelet-activating factor (PAF) promotes transendothelial migration in several vascular beds, and we postulated that increased PAF production in the airways of smokers might enhance inflammatory cell recruitment and exacerbate inflammation. To examine this possibility, we incubated human lung microvascular endothelial cells (HMVEC-L) with cigarette smoke extract (CSE) and found that CSE inhibits PAF-acetylhydrolase (PAF-AH) activity. This enhances HMVEC-L PAF production and PMN adherence, and adherence is blocked by PAF receptor antagonists (CV3988 or ginkgolide B). CSE also inhibited PAF-AH activity of lung endothelial cells isolated from wild-type (WT) and iPLA(2)β knockout mice, and with WT cells, CSE enhanced PAF production and RAW 264.7 cell adherence. In contrast, CSE did not affect PAF production or RAW 264.7 cell adherence to iPLA(2)β-null cells, suggesting that iPLA(2)β plays an important role in PAF production by lung endothelial cells. These findings suggest that inhibition of PAF-AH by components of cigarette smoke may initiate or exacerbate inflammatory lung disease by enhancing PAF production and promoting accumulation of inflammatory cells in small airways. In addition, iPLA(2)β is identified as a potential target for therapeutic interventions to reduce airway inflammation and the progression of chronic lung disease.
Collapse
Affiliation(s)
- Janhavi Sharma
- Department of Pathology, Saint Louis University School of Medicine, St. Louis, Missouri 63104, USA
| | | | | | | | | | | |
Collapse
|
10
|
Abstract
Vascular endothelium is a key regulator of homeostasis. In physiological conditions it mediates vascular dilatation, prevents platelet adhesion, and inhibits thrombin generation. However, endothelial dysfunction caused by physical injury of the vascular wall, for example during balloon angioplasty, acute or chronic inflammation, such as in atherothrombosis, creates a proinflammatory environment which supports leukocyte transmigration toward inflammatory sites. At the same time, the dysfunction promotes thrombin generation, fibrin deposition, and coagulation. The serine protease thrombin plays a pivotal role in the coagulation cascade. However, thrombin is not only the key effector of coagulation cascade; it also plays a significant role in inflammatory diseases. It shows an array of effects on endothelial cells, vascular smooth muscle cells, monocytes, and platelets, all of which participate in the vascular pathophysiology such as atherothrombosis. Therefore, thrombin can be considered as an important modulatory molecule of vascular homeostasis. This review summarizes the existing evidence on the role of thrombin in vascular inflammation.
Collapse
|
11
|
McHowat J, Gullickson G, Hoover RG, Sharma J, Turk J, Kornbluth J. Platelet-activating factor and metastasis: calcium-independent phospholipase A2β deficiency protects against breast cancer metastasis to the lung. Am J Physiol Cell Physiol 2011; 300:C825-32. [PMID: 21228317 DOI: 10.1152/ajpcell.00502.2010] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
We determined the contribution of calcium-independent phospholipase A(2)β (iPLA(2)β) to lung metastasis development following breast cancer injection into wild-type (WT) and iPLA(2)β-knockout (iPLA(2)β-KO) mice. WT and iPLA(2)β-KO mice were injected in the mammary pad with 200,000 E0771 breast cancer cells. There was no difference in primary tumor size between WT and iPLA(2)β-KO mice at 27 days postinjection. However, we observed an 11-fold greater number of breast cancer cells in the lungs of WT mice compared with iPLA(2)β-KO animals (P < 0.05). Isolated WT lung endothelial cells demonstrated a significant increase in platelet-activating factor (PAF) production when stimulated with thrombin [1 IU/ml, 10 min, 4,330 ± 555 vs. 15,227 ± 1,043 disintegrations per minute (dpm), P < 0.01] or TNF-α (10 ng/ml, 2 h, 16,532 ± 538 dpm, P < 0.01). Adherence of E0771 cells to WT endothelial cells was increased by thrombin (4.8 ± 0.3% vs. 70.9 ± 6.3, P < 0.01) or TNF-α (60.5 ± 4.3, P < 0.01). These responses were blocked by pretreatment with the iPLA(2)β-selective inhibitor (S)-bromoenol lactone and absent in lung endothelial cells from iPLA(2)β-KO mice. These data indicate that endothelial cell iPLA(2)β is responsible for PAF production and adherence of E0771 cells and may play a role in cancer cell migration to distal locations.
Collapse
Affiliation(s)
- Jane McHowat
- Department of Pathology, Saint Louis University School of Medicine, Missouri 63104, USA.
| | | | | | | | | | | |
Collapse
|
12
|
Sharma J, Turk J, Mancuso DJ, Sims HF, Gross RW, McHowat J. Activation of group VI phospholipase A2 isoforms in cardiac endothelial cells. Am J Physiol Cell Physiol 2010; 300:C872-9. [PMID: 21191104 DOI: 10.1152/ajpcell.00289.2010] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The endothelium comprises a cellular barrier between the circulation and tissues. We have previously shown that activation of protease-activated receptor 1 (PAR-1) and PAR-2 on the surface of human coronary artery endothelial cells by tryptase or thrombin increases group VIA phospholipase A(2) (iPLA(2)β) activity and results in production of multiple phospholipid-derived inflammatory metabolites. We isolated cardiac endothelial cells from hearts of iPLA(2)β-knockout (iPLA(2)β-KO) and wild-type (WT) mice and measured arachidonic acid (AA), prostaglandin I(2) (PGI(2)), and platelet-activating factor (PAF) production in response to PAR stimulation. Thrombin (0.1 IU/ml) or tryptase (20 ng/ml) stimulation of WT endothelial cells rapidly increased AA and PGI(2) release and increased PAF production. Selective inhibition of iPLA(2)β with (S)-bromoenol lactone (5 μM, 10 min) completely inhibited thrombin- and tryptase-stimulated responses. Thrombin or tryptase stimulation of iPLA(2)β-KO endothelial cells did not result in significant PAF production and inhibited AA and PGI(2) release. Stimulation of cardiac endothelial cells from group VIB (iPLA(2)γ)-KO mice increased PAF production to levels similar to those of WT cells but significantly attenuated PGI(2) release. These results indicate that cardiac endothelial cell PAF production is dependent on iPLA(2)β activation and that both iPLA(2)β and iPLA(2)γ may be involved in PGI(2) release.
Collapse
Affiliation(s)
- Janhavi Sharma
- Department of Pathology, Saint Louis University School of Medicine, Missouri, USA
| | | | | | | | | | | |
Collapse
|
13
|
Urothelial cell platelet-activating factor production mediated by calcium-independent phospholipase A2γ. Urology 2010; 77:248.e1-7. [PMID: 21094990 DOI: 10.1016/j.urology.2010.08.032] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2010] [Revised: 07/20/2010] [Accepted: 08/21/2010] [Indexed: 11/22/2022]
Abstract
OBJECTIVES To determine the effect of phospholipase A(2) (PLA(2)) inhibitors on urothelial cell platelet-activating factor (PAF) production in response to tryptase stimulation. METHODS Urothelial cells isolated from normal human ureters were immortalized with the human papillomavirus type 16E6E7 cell line (TEU-2 cells). PLA(2) activity in TEU-2 cells was measured using (16:0, [(3)H]18:1) plasmenylcholine and phosphatidylcholine substrates in the presence and absence of calcium. [(3)H]PAF production was measured in TEU-2 cells prelabeled with [(3)H] acetic acid. PAF-acetylhydrolase activity was measured by determining the amount of [(3)H] acetate hydrolyzed from [(3)H]PAF incubated with TEU-2 cellular protein. Adherence of human polymorphonuclear leukocyte (PMN) to TEU-2 cells was assessed by measuring myeloperoxidase activity in adherent PMNs after incubation with TEU-2 cells. RESULTS Most PLA(2) activity measured in TEU-2 cells was determined to be membrane-associated, calcium-independent PLA(2) and selective for plasmenylcholine substrate. Stimulation of TEU-2 cells with tryptase results in increased production of PAF and increased PMN adherence that were inhibited completely by pretreatment with the membrane-associated, calcium-independent PLA(2)γ-selective inhibitor (R)-bromoenol lactone. Pretreatment with the cytosolic PLA(2) inhibitor methyl arachidonyl fluorophosphonate resulted in potentiation of tryptase-stimulated PAF production and PMN adherence to TEU-2 cells that is a result of PAF-acetylhydrolase inhibition. CONCLUSIONS Tryptase stimulation of TEU-2 cells results in activation of membrane-associated, calcium-independent PLA(2)γ, leading to an increase in PAF production and increased PMN adherence. Inhibition of TEU-2 cell PAF-acetylhydrolase activity with methyl arachidonyl fluorophosphonate potentiated tryptase-stimulated PAF production and PMN adherence.
Collapse
|
14
|
Sharma J, Rastogi P, Creer MH, McHowat J. Polymorphonuclear leukocytes isolated from umbilical cord blood as a useful research tool to study adherence to cell monolayers. J Immunol Methods 2009; 351:30-5. [PMID: 19800347 DOI: 10.1016/j.jim.2009.09.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2009] [Revised: 09/22/2009] [Accepted: 09/24/2009] [Indexed: 10/20/2022]
Abstract
One of the initial steps in the inflammatory process involves the adherence and transmigration of circulating polymorphonuclear leukocytes (PMN) across the endothelial cell monolayer. One of the main constituents of the neutrophil phagosome that contributes to bacterial killing is myeloperoxidase (MPO) which can be measured spectrophotometrically, using hydrogen peroxide as a substrate, and hence can be used as an index to quantify neutrophil adherence. To evaluate whether PMN isolated from umbilical cord blood could be used for in vitro experiments to monitor neutrophil adherence, we compared the adherence to confluent endothelial and epithelial cell monolayers using PMN isolated from umbilical cord and adult peripheral blood. The extent of PMN adherence was assessed by measuring MPO activity. In initial experiments, we isolated PMN from umbilical cord and adult peripheral blood and measured MPO activity with respect to cell number and assay incubation times. Our data demonstrate that PMN obtained from either source had similar MPO activity and similar adherence to endothelial or epithelial cells. In conclusion, our data suggest that umbilical cord blood is a suitable source of leukocytes to examine PMN adherence in the setting of inflammation in a variety of disease processes.
Collapse
Affiliation(s)
- Janhavi Sharma
- Department of Pathology, Saint Louis University School of Medicine, 1402 S. grand Blvd., St Louis, Missouri 63104, USA
| | | | | | | |
Collapse
|
15
|
Kitsiouli E, Nakos G, Lekka ME. Phospholipase A2 subclasses in acute respiratory distress syndrome. Biochim Biophys Acta Mol Basis Dis 2009; 1792:941-53. [PMID: 19577642 DOI: 10.1016/j.bbadis.2009.06.007] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2009] [Revised: 06/25/2009] [Accepted: 06/25/2009] [Indexed: 01/12/2023]
Abstract
Phospholipases A2 (PLA2) catalyse the cleavage of fatty acids esterified at the sn-2 position of glycerophospholipids. In acute lung injury-acute respiratory distress syndrome (ALI-ARDS) several distinct isoenzymes appear in lung cells and fluid. Some are capable to trigger molecular events leading to enhanced inflammation and lung damage and others have a role in lung surfactant recycling preserving lung function: Secreted forms (groups sPLA2-IIA, -V, -X) can directly hydrolyze surfactant phospholipids. Cytosolic PLA2 (cPLA2-IVA) requiring Ca2+ has a preference for arachidonate, the precursor of eicosanoids which participate in the inflammatory response in the lung. Ca(2+)-independent intracellular PLA2s (iPLA2) take part in surfactant phospholipids turnover within alveolar cells. Acidic Ca(2+)-independent PLA2 (aiPLA2), of lysosomal origin, has additionally antioxidant properties, (peroxiredoxin VI activity), and participates in the formation of dipalmitoyl-phosphatidylcholine in lung surfactant. PAF-AH degrades PAF, a potent mediator of inflammation, and oxidatively fragmented phospholipids but also leads to toxic metabolites. Therefore, the regulation of PLA2 isoforms could be a valuable approach for ARDS treatment.
Collapse
Affiliation(s)
- Eirini Kitsiouli
- Department of Biological Applications and Technologies, School of Sciences and Technologies, University of Ioannina, Greece
| | | | | |
Collapse
|
16
|
Foulks JM, Weyrich AS, Zimmerman GA, McIntyre TM. A yeast PAF acetylhydrolase ortholog suppresses oxidative death. Free Radic Biol Med 2008; 45:434-42. [PMID: 18489912 PMCID: PMC2603548 DOI: 10.1016/j.freeradbiomed.2008.04.034] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/05/2008] [Revised: 04/17/2008] [Accepted: 04/18/2008] [Indexed: 11/26/2022]
Abstract
Phospholipids containing sn-2 polyunsaturated fatty acyl residues are primary targets of oxidizing radicals, producing proapoptotic and membrane perturbing fragmented phospholipids. The only known phospholipases that specifically select these oxidized and/or short-chained phospholipids as substrates are mammalian group VII phospholipases A2s that were purified and cloned as PAF acetylhydrolases. Platelet-activating factor (PAF) is a short-chained phospholipid, and whether these enzymes actually are PAF hydrolases or evolved as oxidized phospholipid phospholipases is unknown. The fission yeast Schizosaccharomyces pombe, which does not form or use PAF as a signaling molecule, contains an open-reading frame potentially homologous to mammalian group VII phospholipase A2s. We cloned this SPBC106.11c locus and expressed it in distantly related Saccharomyces cerevisiae that lack homologous sequences. The S. pombe locus encoded a functional phospholipase A2, now renamed plg7+, that hydrolyzed PAF and a synthetic oxidized phospholipid. Expression of human type II PAF acetylhydrolase or S. pombe Plg7p enhanced the viability of S. cerevisiae subjected to oxidative stress. We conclude that a single-celled organism with an exceedingly spare genome still expresses an unusually discriminating phospholipase A2, and that selective hydrolysis of phospholipid oxidation products is an early, and critical, way to overcome oxidative membrane damage and oxidant-induced cell death.
Collapse
Affiliation(s)
- Jason M. Foulks
- Department of Experimental Pathology, University of Utah School of Medicine, Salt Lake City, UT, 84112
- Department of Internal Medicine and Human Molecular Biology and Genetics, University of Utah School of Medicine, Salt Lake City, UT, 84112
| | - Andrew S. Weyrich
- Department of Internal Medicine and Human Molecular Biology and Genetics, University of Utah School of Medicine, Salt Lake City, UT, 84112
| | - Guy A. Zimmerman
- Department of Internal Medicine and Human Molecular Biology and Genetics, University of Utah School of Medicine, Salt Lake City, UT, 84112
| | - Thomas M. McIntyre
- Department of Cell Biology, Lerner Research Institute, Cleveland Clinic Lerner College of Medicine of CWRU, 9500 Euclid Ave, Cleveland, OH 44195
| |
Collapse
|
17
|
Ahn K, McKinney MK, Cravatt BF. Enzymatic pathways that regulate endocannabinoid signaling in the nervous system. Chem Rev 2008; 108:1687-707. [PMID: 18429637 DOI: 10.1021/cr0782067] [Citation(s) in RCA: 408] [Impact Index Per Article: 25.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Kay Ahn
- Pfizer Global Research and Development, Groton, Connecticut 06340, USA.
| | | | | |
Collapse
|
18
|
Cummings BS. Phospholipase A2 as targets for anti-cancer drugs. Biochem Pharmacol 2007; 74:949-59. [PMID: 17531957 DOI: 10.1016/j.bcp.2007.04.021] [Citation(s) in RCA: 116] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2007] [Revised: 04/23/2007] [Accepted: 04/24/2007] [Indexed: 02/04/2023]
Abstract
Phospholipase A(2) (PLA(2)) are esterases that cleave glycerophospholipids to release fatty acids and lysophospholipids. Inhibition of PLA(2) alters cancer cell growth and death in vitro and PLA(2) expression is increased in breast, lung, and prostate cancers compared to control tissues. Thus, PLA(2) may be novel targets for chemotherapeutics. However, PLA(2) are a diverse family of enzymes, encompassing 19 members. The selectivity of these individual PLA(2) for phospholipids varies, as does their location within the cell, and tissue expression. Thus, their role in cancer may also vary. This review summarizes the expression of individual PLA(2) in cancers, focuses on the potential mechanisms by which these esterases mediate carcinogenesis, and suggests that select PLA(2) isoforms may be targets for anti-cancer drugs.
Collapse
Affiliation(s)
- Brian S Cummings
- Department of Pharmaceutical and Biomedical Sciences, University of Georgia, Athens, GA 30602, USA.
| |
Collapse
|
19
|
Chen J, Yang L, Foulks JM, Weyrich AS, Marathe GK, McIntyre TM. Intracellular PAF catabolism by PAF acetylhydrolase counteracts continual PAF synthesis. J Lipid Res 2007; 48:2365-76. [PMID: 17693621 DOI: 10.1194/jlr.m700325-jlr200] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Stimulated inflammatory cells synthesize platelet-activating factor (PAF), but lysates of these cells show little enhancement in PAF synthase activity. We show that human neutrophils contain intracellular plasma PAF acetylhydrolase (PLA2G7), an enzyme normally secreted by monocytes. The esterase inhibitors methyl arachidonoylfluorophosphonate (MAFP), its linoleoyl homolog, and Pefabloc inhibit plasma PAF acetylhydrolase. All of these inhibitors induced PAF accumulation by quiescent neutrophils and monocytes that was equivalent to agonist stimulation. Agonist stimulation after esterase inhibition did not further increase PAF accumulation. PAF acetylhydrolase activity in intact neutrophils was reduced, but not abolished, by agonist stimulation. Erythrocytes, which do not participate in the acute inflammatory response, inexplicably express the type I PAF acetylhydrolase, whose only known substrate is PAF. Inhibition of this enzyme by MAFP caused PAF accumulation by erythrocytes, which was hemolytic in the absence of PAF acetylhydrolase activity. We propose that PAF is continuously synthesized by a nonselective acyltransferase activity(ies) found even in noninflammatory cells as a component of membrane remodeling, which is then selectively and continually degraded by intracellular PAF acetylhydrolase activity to modulate PAF production.
Collapse
Affiliation(s)
- Jiawei Chen
- Department of Cell Biology, Cleveland Clinic Lerner College of Medicine, Cleveland Clinic, Cleveland, OH 44195, USA
| | | | | | | | | | | |
Collapse
|
20
|
Abstract
Oleamide (cis-9,10-octadecenoamide), a fatty acid primary amide discovered in the cerebrospinal fluid of sleep-deprived cats, has a variety of actions that give it potential as a signaling molecule, although these actions have not been extensively investigated in the cardiovascular system. The synthetic pathway probably involves synthesis of oleoylglycine and then conversion to oleamide by peptidylglycine alpha-amidating monooxygenase (PAM); breakdown of oleamide is by fatty acid amide hydrolase (FAAH). Oleamide interacts with voltage-gated Na(+) channels and allosterically with GABA(A) and 5-HT(7) receptors as well as having cannabinoid-like actions. The latter have been suggested to be due to potentiation of the effects of endocannabinoids such as anandamide by inhibiting FAAH-mediated hydrolysis. This might underlie an "entourage effect" whereby co-released endogenous nonagonist congeners of endocannabinoids protect the active molecule from hydrolysis by FAAH. However, oleamide has direct agonist actions at CB(1) cannabinoid receptors and also activates the TRPV1 vanilloid receptor. Other actions include inhibition of gap-junctional communication, and this might give oleamide a role in myocardial development. Many of these actions are absent from the trans isomer of 9,10-octadecenoamide. One of the most potent actions of oleamide is vasodilation. In rat small mesenteric artery the response does not involve CB(1) cannabinoid receptors but another pertussis toxin-sensitive, G protein-coupled receptor, as yet unidentified. This receptor is sensitive to rimonabant and O-1918, an antagonist at the putative "abnormal-cannabidiol" or endothelial "anandamide" receptors. Vasodilation is mediated by endothelium-derived nitric oxide, endothelium-dependent hyperpolarization, and also through activation of TRPV1 receptors. A physiological role for oleamide in the heart and circulation has yet to be demonstrated, as has production by cells of the cardiovascular system, but this molecule has a range of actions that could give it considerable modulatory power.
Collapse
Affiliation(s)
- C Robin Hiley
- Department of Pharmacology, University of Cambridge, Cambridge, CB2 1PD, UK.
| | | |
Collapse
|
21
|
Rastogi P, Beckett CS, McHowat J. Prostaglandin production in human coronary artery endothelial cells is modulated differentially by selective phospholipase A(2) inhibitors. Prostaglandins Leukot Essent Fatty Acids 2007; 76:205-12. [PMID: 17374479 DOI: 10.1016/j.plefa.2006.12.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/28/2006] [Revised: 11/21/2006] [Accepted: 12/29/2006] [Indexed: 10/23/2022]
Abstract
Atherosclerotic plaque formation is a dynamic process involving repeated injury and inflammation of the endothelium. We have demonstrated previously that thrombin and tryptase stimulation of human coronary artery endothelial cells (HCAEC) leads to increased phospholipase A(2) (PLA(2)) activity and generation of membrane phospholipid derived inflammatory metabolites, including eicosanoids and platelet activating factor. Thus, our hypothesis is that selective PLA(2) inhibitors have therapeutic potential as anti-inflammatory agents. Stimulation of confluent HCAEC monolayers with thrombin or tryptase resulted in a concentration and time-dependent increase in both prostaglandin E(2) (PGE(2)) and prostacyclin (PGI(2)) production. Pretreatment with PX-18 to inhibit secretory PLA(2) or BEL to inhibit calcium-independent PLA(2) prior to thrombin or tryptase stimulation resulted in a significant inhibition of both PGI(2) and PGE(2) release. However, pretreatment with methyl arachidonyl fluorophosphonate (MAFP), a widely used inhibitor of cytosolic PLA(2) isoforms, resulted in a significant potentiation of both thrombin and tryptase stimulated PGI(2) and PGE(2) release as a consequence of increased free arachidonic acid production. We conclude that the use of selective PLA(2) inhibitors may be of therapeutic benefit in the development and progression of atherosclerosis, however, the development of such an agent requires rigorous screening.
Collapse
Affiliation(s)
- P Rastogi
- Department of Pathology, School of Medicine, Saint Louis University, 1402 S. Grand Blvd., St. Louis, MO 63104, USA
| | | | | |
Collapse
|
22
|
Kriska T, Marathe GK, Schmidt JC, McIntyre TM, Girotti AW. Phospholipase Action of Platelet-activating Factor Acetylhydrolase, but Not Paraoxonase-1, on Long Fatty Acyl Chain Phospholipid Hydroperoxides. J Biol Chem 2007; 282:100-8. [PMID: 17090529 DOI: 10.1074/jbc.m608135200] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Phospholipid hydroperoxide (PLOOH) degrading activity of high density lipoprotein (HDL)-derived paraoxonase-1 (PON1) was investigated, using peroxidized 1-palmitoyl-2-oleoyl phosphatidylcholine (PCOOH) as substrate and high performance thin layer chromatography for quantitative peroxide analysis. Incubation of PCOOH with PON1 resulted in decay of the latter and reciprocal buildup of oleic acid hydroperoxide (OAOOH) at rates unaffected by GSH or other reductants. A serine esterase inhibitor blocked this activity and a recombinant PON1 was devoid of it, raising the possibility that the activity represents platelet-activating factor acetylhydrolase (PAF-AH), an esterase that co-purifies with PON1 from HDL. This was verified by showing that a recombinant PAF-AH recapitulates the ability of natural PON1 to hydrolyze PCOOH and release OAOOH while having essentially no effect on parental PC. Furthermore, recombinant PAF-AH and natural PON1 were shown to have similar K(m) values for PCOOH hydrolysis. Finally, we found that recombinant PAF-AH, but not PON1, catalyzes PLOOH hydrolysis in peroxidized low density lipoprotein. We conclude from this study that PON1 is neither a PLOOH peroxidase nor hydrolase and that the phospholipase A(2)-like activity previously attributed to PON1 in natural enzyme preparations was actually due to novel PLOOH hydrolytic activity of contaminating PAF-AH.
Collapse
Affiliation(s)
- Tamas Kriska
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA
| | | | | | | | | |
Collapse
|
23
|
Forlenza OV, Mendes CT, Marie SKN, Gattaz WF. Inhibition of phospholipase A2 reduces neurite outgrowth and neuronal viability. Prostaglandins Leukot Essent Fatty Acids 2007; 76:47-55. [PMID: 17187973 DOI: 10.1016/j.plefa.2006.10.002] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/03/2006] [Revised: 09/27/2006] [Accepted: 10/06/2006] [Indexed: 10/23/2022]
Abstract
Phospholipase A2 (PLA(2)) has been implicated in neurodevelopmental processes and in the early development of the nervous system. We investigated the effects of the inhibition of calcium-dependent and calcium-independent subtypes of cytosolic PLA2 (cPLA2 and iPLA2) on the development and viability of primary cultures of cortical and hippocampal neurons. PLA2 in these cultures was continuously inhibited with methylarachidonyl-fluorophosphonate (MAFP), an irreversible inhibitor of cPLA2 and iPLA2, or with bromoenol lactone (BEL), an irreversible selective iPLA2 inhibitor. The effect of PLA2 inhibitors on the development of neuronal cultures was ascertained by total cell count and morphological characterisation. Neuronal viability was quantified with MTT assays. Inhibition of PLA2 resulted in reduction of neuritogenesis and neuronal viability, disrupting neuronal homeostasis and leading to neuronal death. We conclude that the functional integrity of both calcium-dependent and calcium-independent cytosolic PLA2 is necessary for the in vitro development of cortical and hippocampal neurons.
Collapse
Affiliation(s)
- Orestes V Forlenza
- Laboratory of Neuroscience (LIM-27), Department and Institute of Psychiatry, Faculty of Medicine, University of Sao Paulo, Rua Dr. Ovídio Pires de Campos s/n, 05403-010 Sao Paulo, Brazil.
| | | | | | | |
Collapse
|
24
|
Meyer MC, McHowat J. Calcium-independent phospholipase A2-catalyzed plasmalogen hydrolysis in hypoxic human coronary artery endothelial cells. Am J Physiol Cell Physiol 2007; 292:C251-8. [PMID: 16943248 DOI: 10.1152/ajpcell.00120.2006] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Thrombin stimulation of human coronary artery endothelial cells (HCAEC) results in activation of a membrane-associated, calcium-independent phospholipase A2(iPLA2) that selectively hydrolyzes membrane plasmalogen phospholipids. Rupture of an atherosclerotic plaque and occlusion of the coronary vasculature results in a coronary ischemic event in which HCAEC in the ischemic area would be exposed to dramatic decreases in oxygen tension in addition to thrombin exposure. We exposed HCAEC to hypoxia in the presence or absence of thrombin stimulation and measured iPLA2activation, membrane phospholipid hydrolysis, and the accumulation of biologically active phospholipid metabolites. HCAEC exposed to hypoxia, thrombin stimulation, or a combination of the two conditions demonstrated an increase in iPLA2activity and an increase in arachidonic acid release from plasmenylcholine. Thrombin stimulation of normoxic HCAEC did not result in an accumulation of choline lysophospholipids, but hypoxia alone and in combination with thrombin stimulation led to a significant accumulation of lysoplasmenylcholine (LPlsCho). We propose that the presence of hypoxia inhibits LPlsCho catabolism, at least in part, as a result of the accumulation of long-chain acylcarnitines. The combination of increased production and decreased catabolism of LPlsCho is necessary for its accumulation. Pretreatment with bromoenol lactone to inhibit iPLA2blocked membrane phospholipid hydrolysis and production of membrane phospholipid-derived metabolites. The increase in iPLA2activity and the subsequent accumulation of membrane phospholipid-derived metabolites in HCAEC exposed to hypoxia or thrombin stimulation alone, and particularly in combination, have important implications in inflammation and arrhythmogenesis in atherosclerosis/thrombosis and subsequent myocardial ischemia.
Collapse
Affiliation(s)
- Maureen C Meyer
- Department of Pathology, Saint Louis University School of Medicine, 1402 S. Grand Blvd., St. Louis, MO 63104, USA
| | | |
Collapse
|
25
|
Kinsey GR, McHowat J, Beckett CS, Schnellmann RG. Identification of calcium-independent phospholipase A2gamma in mitochondria and its role in mitochondrial oxidative stress. Am J Physiol Renal Physiol 2006; 292:F853-60. [PMID: 17047165 DOI: 10.1152/ajprenal.00318.2006] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Oxidant-induced lipid peroxidation and cell death mediate pathologies associated with ischemia-reperfusion and inflammation. Our previous work in rabbit renal proximal tubular cells (RPTC) demonstrated that inhibition of Ca(2+)-independent phospholipase A(2) (iPLA(2)) potentiates oxidant-induced lipid peroxidation and necrosis, implicating iPLA(2) in phospholipid repair. This study was conducted to identify a RPTC mitochondrial PLA(2) and determine the role of PLA(2) in oxidant-induced mitochondrial dysfunction. iPLA(2) activity was detected in Percoll-purified rabbit renal cortex mitochondria (RCM) and in isolated mitochondrial inner membrane fractions from rabbit and human RCM. Immunoblot analysis and inhibitor sensitivity profiles revealed that iPLA(2)gamma is the RCM iPLA(2) activity. RCM iPLA(2) activity was enhanced in the presence of ATP and was blocked by the PKCepsilon V1-2 inhibitor. Oxidant-induced mitochondrial lipid peroxidation and swelling were accelerated by pretreatment with R-BEL, but not S-BEL. Furthermore, oxidant treatment of isolated RCM resulted in decreased iPLA(2)gamma activity. These results reveal that RCM iPLA(2) is iPLA(2)gamma, RCM iPLA(2)gamma is regulated by phosphorylation by PKCepsilon, iPLA(2)gamma protects RCM from oxidant-induced lipid peroxidation and dysfunction, and that a strategy to preserve or enhance iPLA(2)gamma activity may be of therapeutic benefit.
Collapse
Affiliation(s)
- Gilbert R Kinsey
- Dept. of Pharmaceutical Sciences, Medical University of South Carolina, Charleston, SC 29425, USA
| | | | | | | |
Collapse
|
26
|
Flamand N, Picard S, Lemieux L, Pouliot M, Bourgoin SG, Borgeat P. Effects of pyrrophenone, an inhibitor of group IVA phospholipase A2, on eicosanoid and PAF biosynthesis in human neutrophils. Br J Pharmacol 2006; 149:385-92. [PMID: 16967052 PMCID: PMC1978440 DOI: 10.1038/sj.bjp.0706879] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
BACKGROUND AND PURPOSE The biosynthesis of leukotrienes (LT) and platelet-activating factor (PAF) involves the release of their respective precursors, arachidonic acid (AA) and lyso-PAF by the group IVA PLA2 (cPLA2alpha). This paper aims at characterizing the inhibitory properties of the cPLA2alpha inhibitor pyrrophenone on eicosanoids and PAF in human neutrophils (PMN). EXPERIMENTAL APPROACH Freshly isolated human PMN were activated with physiological and pharmacological agents (fMLP, PAF, exogenous AA, A23187 and thapsigargin) in presence and absence of the cPLA2alpha inhibitor pyrrophenone and biosynthesis of LT, PAF, and PGE2 was measured. KEY RESULTS Pyrrophenone potently inhibited LT, PGE2 and PAF biosynthesis in PMN with IC50s in the range of 1-20 nM. These inhibitory effects of pyrrophenone were specific (the consequence of substrate deprivation), as shown by the reversal of inhibition by exogenous AA and lyso-PAF. Comparative assessment of pyrrophenone, methyl-arachidonoyl-fluoro-phosphonate (MAFP) and arachidonoyl-trifluoromethylketone (AACOCF3) demonstrated that pyrrophenone was more specific and 100-fold more potent than MAFP and AACOCF3 for the inhibition of LT biosynthesis in A23187-activated PMN. The inhibitory effect of pyrrophenone on LT biosynthesis was reversible as LT biosynthesis was recovered when pyrrophenone-treated PMN were washed with autologous plasma. No alteration of phospholipase D (PLD) activity in fMLP-activated PMN was observed with up to 10 microM pyrrophenone, suggesting that the cPLA2alpha inhibitor does not directly inhibit PLD. CONCLUSIONS AND IMPLICATIONS Pyrrophenone is a more potent and specific cPLA2alpha inhibitor than MAFP and AACOCF3 and represents an excellent pharmacological tool to investigate the biosynthesis and the biological roles of eicosanoids and PAF.
Collapse
Affiliation(s)
- N Flamand
- Département d'anatomic et de physiologie, Centre de Recherche en Rhumatologie et Immunologie, Centre de recherche du CHUQ (CHUL), Faculté de Médecine, Université Laval Québec, Canada
| | - S Picard
- Département d'anatomic et de physiologie, Centre de Recherche en Rhumatologie et Immunologie, Centre de recherche du CHUQ (CHUL), Faculté de Médecine, Université Laval Québec, Canada
| | - L Lemieux
- Département d'anatomic et de physiologie, Centre de Recherche en Rhumatologie et Immunologie, Centre de recherche du CHUQ (CHUL), Faculté de Médecine, Université Laval Québec, Canada
| | - M Pouliot
- Département d'anatomic et de physiologie, Centre de Recherche en Rhumatologie et Immunologie, Centre de recherche du CHUQ (CHUL), Faculté de Médecine, Université Laval Québec, Canada
| | - S G Bourgoin
- Département d'anatomic et de physiologie, Centre de Recherche en Rhumatologie et Immunologie, Centre de recherche du CHUQ (CHUL), Faculté de Médecine, Université Laval Québec, Canada
| | - P Borgeat
- Département d'anatomic et de physiologie, Centre de Recherche en Rhumatologie et Immunologie, Centre de recherche du CHUQ (CHUL), Faculté de Médecine, Université Laval Québec, Canada
- Author for correspondence:
| |
Collapse
|
27
|
Schaloske RH, Dennis EA. The phospholipase A2 superfamily and its group numbering system. Biochim Biophys Acta Mol Cell Biol Lipids 2006; 1761:1246-59. [PMID: 16973413 DOI: 10.1016/j.bbalip.2006.07.011] [Citation(s) in RCA: 627] [Impact Index Per Article: 34.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2006] [Revised: 07/05/2006] [Accepted: 07/29/2006] [Indexed: 01/07/2023]
Abstract
The superfamily of phospholipase A(2) (PLA(2)) enzymes currently consists of 15 Groups and many subgroups and includes five distinct types of enzymes, namely the secreted PLA(2)s (sPLA(2)), the cytosolic PLA(2)s (cPLA(2)), the Ca(2+) independent PLA(2)s (iPLA(2)), the platelet-activating factor acetylhydrolases (PAF-AH), and the lysosomal PLA(2)s. In 1994, we established the systematic Group numbering system for these enzymes. Since then, the PLA(2) superfamily has grown continuously and over the intervening years has required several updates of this Group numbering system. Since our last update, a number of new PLA(2)s have been discovered and are now included. Additionally, tools for the investigation of PLA(2)s and approaches for distinguishing between the different Groups are described.
Collapse
Affiliation(s)
- Ralph H Schaloske
- Department of Pharmacology, School of Medicine, University of California at San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0601, USA
| | | |
Collapse
|
28
|
Abstract
Fatty acid amide hydrolase (FAAH) is a mammalian integral membrane enzyme that degrades the fatty acid amide family of endogenous signaling lipids, which includes the endogenous cannabinoid anandamide and the sleep-inducing substance oleamide. FAAH belongs to a large and diverse class of enzymes referred to as the amidase signature (AS) family. Investigations into the structure and function of FAAH, in combination with complementary studies of other AS enzymes, have engendered provocative molecular models to explain how this enzyme integrates into cell membranes and terminates fatty acid amide signaling in vivo. These studies, as well as their biological and therapeutic implications, are the subject of this review.
Collapse
Affiliation(s)
- Michele K McKinney
- Departments of Cell Biology and Chemistry, The Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, California 92037, USA.
| | | |
Collapse
|
29
|
Kessen UA, Schaloske RH, Stephens DL, Killermann Lucas K, Dennis EA. PGE2 release is independent of upregulation of Group V phospholipase A2 during long-term stimulation of P388D1 cells with LPS. J Lipid Res 2005; 46:2488-96. [PMID: 16150819 DOI: 10.1194/jlr.m500325-jlr200] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
P388D1 cells release arachidonic acid (AA) and produce prostaglandin E2 (PGE2) upon long-term stimulation with lipopolysaccharide (LPS). The cytosolic Group IVA (GIVA) phospholipase A2 (PLA2) has been implicated in this pathway. LPS stimulation also results in increased expression and secretion of a secretory PLA2, specifically GV PLA2. To test whether GV PLA2 contributes to PGE2 production and whether GIVA PLA2 activation increases the expression of GV PLA2, we utilized the specific GIVA PLA2 inhibitor pyrrophenone and second generation antisense oligonucleotides (AS-ONs) designed to specifically inhibit expression and activity of GV PLA2. Treatment of P388D1 cells with antisense caused a marked decrease in basal GV PLA2 mRNA and prevented the LPS-induced increase in GV PLA2 mRNA. LPS-stimulated cells release active GV PLA2 into the medium, which is inhibited to background levels by antisense treatment. However, LPS-induced PGE2 release by antisense-treated cells and by control cells are not significantly different. Collectively, the results suggest that the upregulation of GV PLA2 during long-term LPS stimulation is not required for PGE2 production by P388D1 cells. Experiments employing pyrrophenone suggested that GIVA PLA2 is the dominant player involved in AA release, but it appears not to be involved in the regulation of LPS-induced expression of GV PLA2 or cyclooxygenase-2.
Collapse
Affiliation(s)
- Ursula A Kessen
- Department of Chemistry, University of California-San Diego, La Jolla, CA 92093, USA
| | | | | | | | | |
Collapse
|
30
|
Vinson SM, Rickard A, Ryerse JS, McHowat J. Neutrophil Adherence to Bladder Microvascular Endothelial Cells following Platelet-Activating Factor Acetylhydrolase Inhibition. J Pharmacol Exp Ther 2005; 314:1241-7. [PMID: 15937147 DOI: 10.1124/jpet.105.085365] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Interstitial cystitis (IC) is an inflammatory bladder condition of unknown etiology. Tryptase released from elevated numbers of activated mast cells is a proposed mediator of the inflammatory process in IC. We have previously shown that tryptase increases human bladder microvascular endothelial cell (HBMEC) calcium-independent phospholipase A(2) (iPLA(2)) activity, resulting in the production of multiple biologically active phospholipid metabolites, including platelet-activating factor (PAF), that can mediate inflammation. Because the design of selective PLA(2) inhibitors may provide a useful therapeutic strategy to reduce the inflammatory process in IC, we tested several frequently used PLA(2) inhibitors on PAF production in tryptase-stimulated HBMEC. Among the inhibitors tested, methyl arachidonyl fluorophosphonate (MAFP) was found to be a potent inhibitor of PAF-acetylhydrolase activity. Pretreatment of HBMEC with MAFP significantly increased PAF production in both unstimulated and tryptase-stimulated cells. In addition, MAFP pretreatment of tryptase-stimulated HBMEC increased both surface expression of P-selectin and polymorphonuclear leukocyte adherence to the HBMEC monolayer. These effects suggest that MAFP has a proinflammatory effect, irrespective of its ability to inhibit PLA(2).
Collapse
Affiliation(s)
- Suzanne M Vinson
- Department of Pathology, St. Louis University School of Medicine, MO 63104, USA
| | | | | | | |
Collapse
|
31
|
Meyer MC, Kell PJ, Creer MH, McHowat J. Calcium-independent phospholipase A2 is regulated by a novel protein kinase C in human coronary artery endothelial cells. Am J Physiol Cell Physiol 2005; 288:C475-82. [PMID: 15643055 DOI: 10.1152/ajpcell.00306.2004] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We demonstrated previously that thrombin stimulation of endothelial cells activates a membrane-associated, Ca(2+)-independent phospholipase A2 (iPLA2) that selectively hydrolyzes arachidonylated plasmalogen phospholipids. We report that incubation of human coronary artery endothelial cells (HCAEC) with phorbol 12-myristate 13-acetate (PMA) to activate protein kinase C (PKC) resulted in hydrolysis of cellular phospholipids similar to that observed with thrombin stimulation (0.05 IU/ml; 10 min). Thrombin stimulation resulted in a decrease in arachidonylated plasmenylcholine (2.7 +/- 0.1 vs. 5.3 +/- 0.4 nmol PO4/mg of protein) and plasmenylethanolamine (7.5 +/- 1.0 vs. 12.0 +/- 0.9 nmol PO4/mg of protein). Incubation with PMA resulted in decreases in arachidonylated plasmenylcholine (3.2 +/- 0.3 nmol PO4/mg of protein) and plasmenylethanolamine (6.0 +/- 1.0 nmol PO4/mg of protein). Incubation of HCAEC with the selective iPLA2 inhibitor bromoenol lactone (5 mM; 10 min) inhibited accelerated plasmalogen phospholipid hydrolysis in response to both PMA and thrombin stimulation. Incubation of HCAEC with PMA (100 nM; 5 min) resulted in increased arachidonic acid release (7.1 +/- 0.3 vs. 1.1 +/- 0.1%) and increased production of lysoplasmenylcholine (1.4 +/- 0.2 vs. 0.6 +/- 0.1 nmol PO4/mg of protein), similar to the responses observed with thrombin stimulation. Downregulation of PKC by prolonged exposure to PMA (100 nM; 24 h) completely inhibited thrombin-stimulated increases in arachidonic acid release (7.1 +/- 0.6 to 0.5 +/- 0.1%) and lysoplasmenylcholine production (2.0 +/- 0.1 to 0.2 +/- 0.1 nmol PO4/mg of protein). These data suggest that PKC activates iPLA2 in HCAEC, leading to accelerated plasmalogen phospholipid hydrolysis and increased phospholipid metabolite production.
Collapse
Affiliation(s)
- Maureen C Meyer
- Department of Pathology, St. Louis University School of Medicine, St. Louis, Missouri 63104, USA
| | | | | | | |
Collapse
|
32
|
Rickard A, Portell C, Kell PJ, Vinson SM, McHowat J. Protease-activated receptor stimulation activates a Ca2+-independent phospholipase A2 in bladder microvascular endothelial cells. Am J Physiol Renal Physiol 2004; 288:F714-21. [PMID: 15561975 DOI: 10.1152/ajprenal.00288.2004] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Increased mast cell numbers and mast cell activation represent one of the prevalent etiologic theories for interstitial cystitis, an inflammatory condition in the bladder. This study was designed primarily to determine whether increased mast cell tryptase in the bladder wall may play a role in activating bladder endothelial cell phospholipase A(2) (PLA(2)), leading to increased inflammatory phospholipid metabolite accumulation, which may propagate the inflammatory process. We stimulated human bladder microvascular endothelial cells with thrombin or tryptase and measured the activation of PLA(2) and the production of multiple membrane phospholipid-derived inflammatory mediators. Thrombin and tryptase stimulation resulted in activation of a Ca(2+)-independent PLA(2), leading to increased release of arachidonic acid and prostacyclin and increased production of platelet-activating factor. These responses were blocked completely by pretreatment of human bladder microvascular endothelial cells with the Ca(2+)-independent PLA(2)-selective inhibitor bromoenol lactone. The combination of increased prostacyclin and platelet-activating factor in the bladder circulation may result in vasodilation and increased polymorphonuclear leukocyte adherence to the endothelium and may facilitate recruitment of polymorphonuclear leukocytes to the bladder wall of patients with interstitial cystitis.
Collapse
Affiliation(s)
- Alice Rickard
- Dept. of Pathology, Saint Louis Univ. School of Medicine, 1402 S. Grand Blvd., St. Louis, MO 63104, USA
| | | | | | | | | |
Collapse
|