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Lapointe S, Brkovic A, Cloutier I, Tanguay JF, Arm JP, Sirois MG. Group V secreted phospholipase A2 contributes to LPS-induced leukocyte recruitment. J Cell Physiol 2010; 224:127-34. [PMID: 20232296 DOI: 10.1002/jcp.22106] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Secreted phospholipases A(2) (sPLA(2)s) are well known for their contribution in the biosynthesis of inflammatory eicosanoids. These enzymes also participate in the inflammatory process by regulating chemokine production and protein expression of adhesion molecules. The majority of sPLA(2) isoforms are up-regulated by proinflammatory stimuli such as bacterial lipopolysaccharide (LPS), which predominantly increases the expression of group V sPLA(2) (sPLA(2)-V). Furthermore, it has recently been shown that sPLA(2)-V is a critical messenger in the regulation of cell migration during allergic airway responsiveness. Herein, we investigated the effect of sPLA(2)-V on LPS-mediated leukocyte recruitment and its capacity to modulate adhesion molecule expression. We conducted our study in the murine air pouch model, using sPLA(2)-V null mice (sPLA(2)-V(-/-)) and control wild-type (WT) littermates. We observed that LPS (1 microg/ml)-mediated leukocyte emigration in sPLA(2)-V(-/-) was attenuated by 52% and 86% upon 6 and 12 h of treatment respectively, as compared to WT mice. In WT mice, treatment with the cell-permeable sPLA(2) inhibitor (12-epi-scalaradial; SLD) reduced LPS-mediated leukocyte recruitment by 67%, but had no additional inhibitory effect in sPLA(2)-V(-/-) mice. Protein analyses from the air pouch skin were carried out upon LPS-challenge, and the expression of intercellular adhesion molecule (ICAM)-1 and vascular cell adhesion molecule (VCAM)-1 were both significantly reduced in sPLA(2)-V(-/-) mice as compared to control WT mice. Together, our data demonstrate the role of sPLA(2)-V in LPS-induced ICAM-1 and VCAM-1 protein overexpression and leukocyte recruitment, supporting the contribution of sPLA(2)-V in the development of inflammatory innate immune responses.
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Affiliation(s)
- Stéphanie Lapointe
- Research Centre, Montreal Heart Institute, Université de Montréal, Montreal, QC, Canada
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Dudek SM, Muñoz NM, Desai A, Osan CM, Meliton AY, Leff AR. Group V phospholipase A2 mediates barrier disruption of human pulmonary endothelial cells caused by LPS in vitro. Am J Respir Cell Mol Biol 2010; 44:361-8. [PMID: 20448053 DOI: 10.1165/rcmb.2009-0446oc] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
We examined the functional role of 14-kD secretory group V phospholipase A(2) (gVPLA(2)) on the barrier function of pulmonary endothelial cells (ECs) after LPS activation in vitro. Expression of gVPLA(2) was elicited by 20 ng/ml LPS as demonstrated by increased (1) mRNA, (2) protein content, and (3) cell surface expression of gVPLA(2) within 4 hours. The effect of LPS on EC barrier function was measured by transendothelial monolayer electrical resistance (TER). LPS increased permeability across EC monolayers at 2-3 hours, and was sustained for 10 hours or more. Blockade of gVPLA(2) with mouse monoclonal 3G1 (MCL-3G1) monoclonal antibody directed against gVPLA(2) inhibited EC barrier dysfunction elicited by LPS in a time- and concentration-dependent manner; control IgG had no effect on TER. Like LPS, exogenous gVPLA(2) caused increased EC permeability in a time- and concentration-dependent manner; neither gIIaPLA(2), a close homolog of gVPLA(2), nor W31A, an inactive mutant of gVPLA(2), caused a decrease in EC TER. Immunofluorescence analysis revealed comparable F-actin stress fiber and intercellular gap formation for ECs treated with either gVPLA(2) or LPS. Treatment with gVPLA(2) disrupted vascular endothelial-cadherin junctional complexes on ECs. Coincubation of ECs with MCL-3G1 substantially attenuated the structural changes caused by gVPLA(2) or LPS. We demonstrate that (1) gVPLA(2) is constitutively expressed in ECs and is up-regulated after LPS activation, (2) endogenously secreted gVPLA(2) from ECs after LPS increases EC permeability through F-actin and junctional complex rearrangement, and (3) inhibition of endogenous gVPLA(2) from ECs is sufficient to block disruption of the EC barrier function after LPS in vitro.
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Affiliation(s)
- Steven M Dudek
- Section of Pulmonary & Critical Care Medicine, Department of Medicine, University of Chicago, IL 60637, USA.
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53
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Sato H, Taketomi Y, Isogai Y, Miki Y, Yamamoto K, Masuda S, Hosono T, Arata S, Ishikawa Y, Ishii T, Kobayashi T, Nakanishi H, Ikeda K, Taguchi R, Hara S, Kudo I, Murakami M. Group III secreted phospholipase A2 regulates epididymal sperm maturation and fertility in mice. J Clin Invest 2010; 120:1400-14. [PMID: 20424323 DOI: 10.1172/jci40493] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2009] [Accepted: 02/10/2010] [Indexed: 11/17/2022] Open
Abstract
Although lipid metabolism is thought to be important for the proper maturation and function of spermatozoa, the molecular mechanisms that underlie this dynamic process in the gonads remains incompletely understood. Here, we show that group III phospholipase A2 (sPLA2-III), a member of the secreted phospholipase A2 (sPLA2) family, is expressed in the mouse proximal epididymal epithelium and that targeted disruption of the gene encoding this protein (Pla2g3) leads to defects in sperm maturation and fertility. Although testicular spermatogenesis in Pla2g3-/- mice was grossly normal, spermatozoa isolated from the cauda epididymidis displayed hypomotility, and their ability to fertilize intact eggs was markedly impaired. Transmission EM further revealed that epididymal spermatozoa in Pla2g3-/- mice had both flagella with abnormal axonemes and aberrant acrosomal structures. During epididymal transit, phosphatidylcholine in the membrane of Pla2g3+/+ sperm underwent a dramatic shift in its acyl groups from oleic, linoleic, and arachidonic acids to docosapentaenoic and docosahexaenoic acids, whereas this membrane lipid remodeling event was compromised in sperm from Pla2g3-/- mice. Moreover, the gonads of Pla2g3-/- mice contained less 12/15-lipoxygenase metabolites than did those of Pla2g3+/+ mice. Together, our results reveal a role for the atypical sPLA2 family member sPLA2-III in epididymal lipid homeostasis and indicate that its perturbation may lead to sperm dysfunction.
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Affiliation(s)
- Hiroyasu Sato
- Biomembrane Signaling Project, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan
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Murakami M, Taketomi Y, Girard C, Yamamoto K, Lambeau G. Emerging roles of secreted phospholipase A2 enzymes: Lessons from transgenic and knockout mice. Biochimie 2010; 92:561-82. [PMID: 20347923 DOI: 10.1016/j.biochi.2010.03.015] [Citation(s) in RCA: 105] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2009] [Accepted: 03/18/2010] [Indexed: 11/15/2022]
Abstract
Among the emerging phospholipase A(2) (PLA(2)) superfamily, the secreted PLA(2) (sPLA(2)) family consists of low-molecular-mass, Ca(2+)-requiring extracellular enzymes with a His-Asp catalytic dyad. To date, more than 10 sPLA(2) enzymes have been identified in mammals. Individual sPLA(2)s exhibit unique tissue and cellular localizations and enzymatic properties, suggesting their distinct pathophysiological roles. Despite numerous enzymatic and cell biological studies on this enzyme family in the past two decades, their precise in vivo functions still remain largely obscure. Recent studies using transgenic and knockout mice for several sPLA(2) enzymes, in combination with lipidomics approaches, have opened new insights into their distinct contributions to various biological events such as food digestion, host defense, inflammation, asthma and atherosclerosis. In this article, we overview the latest understanding of the pathophysiological functions of individual sPLA(2) isoforms fueled by studies employing transgenic and knockout mice for several sPLA(2)s.
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Affiliation(s)
- Makoto Murakami
- Biomembrane Signaling Project, The Tokyo Metropolitan Institute of Medical Science, 2-1-6 Kamikitazawa, Setagaya-ku, Tokyo 156-8506, Japan.
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55
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The role of mast cell-derived secreted phospholipases A2 in respiratory allergy. Biochimie 2010; 92:588-93. [PMID: 20219624 DOI: 10.1016/j.biochi.2010.02.030] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2009] [Accepted: 02/19/2010] [Indexed: 11/23/2022]
Abstract
Secreted phospholipases A(2) (sPLA(2)s) are molecules released in plasma and biological fluids of patients with systemic inflammatory, autoimmune and allergic diseases. These molecules exert proinflammatory effects by either enzymatic-mechanisms or through binding to surface molecules expressed on inflammatory cells. sPLA(2)s are released at low levels in the normal airways and tend to increase during respiratory allergies (e.g., rhinitis and bronchial asthma) as the result of local secretion. Several sPLA(2) isoforms are expressed in the human lung and some of them (e.g., group IIA and group X) are released in the airways of patients with rhinitis or asthma. Mast cells play a major role in the pathogenesis of respiratory allergies and other chronic inflammatory lung diseases. Recent evidence indicates that mast cells purified from human lung express most of the sPLA(2) isoforms so far described. IgE-mediated activation of these cells induce the release of sPLA(2)s suggesting that mast cells are a main source of extracellular sPLA(2)s during allergic reactions. Once released, sPLA(2)s may contribute to the generation of eicosanoids (e.g., PGD(2) and LTC(4)) and to the release of preformed mediators (e.g., histamine) by an autocrine loop involving the interaction of sPLA(2)s with surface molecules such as heparan sulphate proteoglycans or the M-type receptor. Thus, mast cell-derived sPLA(2)s may play an important role in the initiation and amplification of the inflammatory reactions in patients with allergic rhinitis and bronchial asthma.
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Magrioti V, Kokotos G. Phospholipase A2inhibitors as potential therapeutic agents for the treatment of inflammatory diseases. Expert Opin Ther Pat 2009; 20:1-18. [DOI: 10.1517/13543770903463905] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Abstract
PLA2 (phospholipase A2) group III is an atypical sPLA2 (secretory PLA2) that is homologous with bee venom PLA2 rather than with other mammalian sPLA2s. In the present paper, we show that endogenous group III sPLA2 (PLA2G3) is expressed in mouse skin and that Tg (transgenic) mice overexpressing human PLA2G3 spontaneously develop skin inflammation. Pla2g3-Tg mice over 9 months of age frequently developed dermatitis with hyperkeratosis, acanthosis, parakeratosis, erosion, ulcer and sebaceous gland hyperplasia. The dermatitis was accompanied by infiltration of neutrophils and macrophages and by elevated levels of pro-inflammatory cytokines, chemokines and prostaglandin E2. In addition, Pla2g3-Tg mice had increased lymph aggregates and mucus in the airway, lymphocytic sialadenitis, hepatic extramedullary haemopoiesis, splenomegaly with increased populations of granulocytes and monocytes/macrophages, and increased serum IgG1. Collectively, these observations provide the first demonstration of spontaneous development of inflammation in mice with Tg overexpression of mammalian sPLA2.
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58
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Muñoz NM, Meliton AY, Meliton LN, Dudek SM, Leff AR. Secretory group V phospholipase A2 regulates acute lung injury and neutrophilic inflammation caused by LPS in mice. Am J Physiol Lung Cell Mol Physiol 2009; 296:L879-87. [PMID: 19286925 DOI: 10.1152/ajplung.90580.2008] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
We investigated the regulatory role of 14-kDa secretory group V phospholipase A(2) (gVPLA(2)) in the development of acute lung injury (ALI) and neutrophilic inflammation (NI) caused by intratracheal administration of LPS. Experiments were conducted in gVPLA(2) knockout (pla2g5(-/-)) mice, which lack the gene, and gVPLA(2) wild-type littermate control (pla2g5(+/+)) mice. Indices of pulmonary injury were evaluated 24 h after intratracheal administration of LPS. Expression of gVPLA(2) in microsections of airways and mRNA content in lung homogenates were increased substantially in pla2g5(+/+) mice after LPS-administered compared with saline-treated pla2g5(+/+) mice. By contrast, expression of gVPLA(2) was neither localized in LPS- nor saline-treated pla2g5(-/-) mice. LPS also caused 1) reduced transthoracic static compliance, 2) lung edema, 3) neutrophilic infiltration, and 4) increased neutrophil myeloperoxidase activity in pla2g5(+/+) mice. These events were attenuated in pla2g5(-/-) mice exposed to LPS or in pla2g5(+/+) mice receiving MCL-3G1, a neutralizing MAb directed against gVPLA(2), before LPS administration. Our data demonstrate that gVPLA(2) is an inducible protein in pla2g5(+/+) mice but not in pla2g5(-/-) mice within 24 h after LPS treatment. Specific inhibition of gVPLA(2) with MCL-3G1 or gene-targeted mice lacking gVPLA(2) blocks ALI and attenuates NI caused by LPS.
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Affiliation(s)
- Nilda M Muñoz
- Dept. of Medicine, M6076, Univ. of Chicago, 5841 S. Maryland Ave., Chicago, IL 60637, USA
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59
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Expression of phospholipases A2 in primary human lung macrophages: role of cytosolic phospholipase A2-alpha in arachidonic acid release and platelet activating factor synthesis. Biochim Biophys Acta Mol Cell Biol Lipids 2008; 1791:92-102. [PMID: 19130898 DOI: 10.1016/j.bbalip.2008.12.002] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2008] [Revised: 11/24/2008] [Accepted: 12/05/2008] [Indexed: 10/21/2022]
Abstract
Macrophages are a major source of lipid mediators in the human lung. Expression and contribution of cytosolic (cPLA(2)) and secreted phospholipases A(2) (sPLA(2)) to the generation of lipid mediators in human macrophages are unclear. We investigated the expression and role of different PLA(2)s in the production of lipid mediators in primary human lung macrophages. Macrophages express the alpha, but not the zeta isoform of group IV and group VIA cPLA(2) (iPLA(2)). Two structurally-divergent inhibitors of group IV cPLA(2) completely block arachidonic acid release by macrophages in response to non-physiological (Ca(2+) ionophores and phorbol esters) and physiological agonists (lipopolysaccharide and Mycobacterium protein derivative). These inhibitors also reduce by 70% the synthesis of platelet-activating factor by activated macrophages. Among the full set of human sPLA(2)s, macrophages express group IIA, IID, IIE, IIF, V, X and XIIA, but not group IB and III enzymes. Me-Indoxam, a potent and cell impermeable inhibitor of several sPLA(2)s, has no effect on arachidonate release or platelet-activating factor production. Agonist-induced exocytosis is not influenced by cPLA(2) inhibitors at concentrations that block arachidonic acid release. Our results indicate that human macrophages express cPLA(2)-alpha, iPLA(2) and several sPLA(2)s. Cytosolic PLA(2)-alpha is the major enzyme responsible for lipid mediator production in human macrophages.
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60
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Sato H, Kato R, Isogai Y, Saka GI, Ohtsuki M, Taketomi Y, Yamamoto K, Tsutsumi K, Yamada J, Masuda S, Ishikawa Y, Ishii T, Kobayashi T, Ikeda K, Taguchi R, Hatakeyama S, Hara S, Kudo I, Itabe H, Murakami M. Analyses of group III secreted phospholipase A2 transgenic mice reveal potential participation of this enzyme in plasma lipoprotein modification, macrophage foam cell formation, and atherosclerosis. J Biol Chem 2008; 283:33483-97. [PMID: 18801741 DOI: 10.1074/jbc.m804628200] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Among the many mammalian secreted phospholipase A2 (sPLA2) enzymes, PLA2G3 (group III secreted phospholipase A2) is unique in that it possesses unusual N- and C-terminal domains and in that its central sPLA2 domain is homologous to bee venom PLA2 rather than to other mammalian sPLA2s. To elucidate the in vivo actions of this atypical sPLA2, we generated transgenic (Tg) mice overexpressing human PLA2G3. Despite marked increases in PLA2 activity and mature 18-kDa PLA2G3 protein in the circulation and tissues, PLA2G3 Tg mice displayed no apparent abnormality up to 9 months of age. However, alterations in plasma lipoproteins were observed in PLA2G3 Tg mice compared with control mice. In vitro incubation of low density (LDL) and high density (HDL) lipoproteins with several sPLA2s showed that phosphatidylcholine was efficiently converted to lysophosphatidylcholine by PLA2G3 as well as by PLA2G5 and PLA2G10, to a lesser extent by PLA2G2F, and only minimally by PLA2G2A and PLA2G2E. PLA2G3-modified LDL, like PLA2G5- or PLA2G10-treated LDL, facilitated the formation of foam cells from macrophages ex vivo. Accumulation of PLA2G3 was detected in the atherosclerotic lesions of humans and apoE-deficient mice. Furthermore, following an atherogenic diet, aortic atherosclerotic lesions were more severe in PLA2G3 Tg mice than in control mice on the apoE-null background, in combination with elevated plasma lysophosphatidylcholine and thromboxane A2 levels. These results collectively suggest a potential functional link between PLA2G3 and atherosclerosis, as has recently been proposed for PLA2G5 and PLA2G10.
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Affiliation(s)
- Hiroyasu Sato
- Biomembrane Signaling Project, Tokyo Metropolitan Institute of Medical Science, 3-18-22 Honkomagome, Tokyo 113-8613, Japan
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61
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Oslund RC, Cermak N, Gelb MH. Highly specific and broadly potent inhibitors of mammalian secreted phospholipases A2. J Med Chem 2008; 51:4708-14. [PMID: 18605714 DOI: 10.1021/jm800422v] [Citation(s) in RCA: 117] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We report a series of inhibitors of secreted phospholipases A2 (sPLA2s) based on substituted indoles, 6,7-benzoindoles, and indolizines derived from LY315920, a well-known indole-based sPLA2 inhibitor. Using the human group X sPLA2 crystal structure, we prepared a highly potent and selective indole-based inhibitor of this enzyme. Also, we report human and mouse group IIA and IIE specific inhibitors and a substituted 6,7-benzoindole that inhibits nearly all human and mouse sPLA2s in the low nanomolar range.
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Affiliation(s)
- Rob C Oslund
- Departments of Chemistry and Biochemistry, University of Washington, Seattle, Washington 98195, USA
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62
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Multiple roles of phospholipase A2 during lung infection and inflammation. Infect Immun 2008; 76:2259-72. [PMID: 18411286 DOI: 10.1128/iai.00059-08] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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63
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Murakami M. Physiological roles of secreted phospholipase A2 enzymes. Inflamm Regen 2008. [DOI: 10.2492/inflammregen.28.454] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
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