101
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Wu K, Zhang Y. Clinical application of tear proteomics: Present and future prospects. Proteomics Clin Appl 2007; 1:972-82. [DOI: 10.1002/prca.200700125] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2007] [Indexed: 01/06/2023]
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102
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Evans DJ, McNamara NA, Fleiszig SMJ. Life at the front: dissecting bacterial-host interactions at the ocular surface. Ocul Surf 2007; 5:213-27. [PMID: 17660895 DOI: 10.1016/s1542-0124(12)70612-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The ocular surface usually looks quiet, presenting a general impression of biological inactivity. Yet, the ability of the cornea to maintain health while continually exposed to environmental insults, and in the relative absence of immune strategies afforded by other body sites, reflects its complexity. Because it is critical for transparency and, therefore, our survival, the fine structure of the cornea has likely provided the driving force for the evolution of what appears to be a truly remarkable system. While several molecules are now known to participate, we are only beginning to obtain the knowledge to fully explain the mechanisms involved in corneal resistance to infection. Full explanation will require a better understanding of the interplay between microbes and various components of the ocular surface, and of the critical factors determining health as the usual outcome. To understand infectious disease, we need to consider how the scenario changes in conditions associated with susceptibility. What we learn in the process could yield a wealth of potential therapies for a wide variety of diseases of the eye and of other sites.
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Affiliation(s)
- David J Evans
- School of Optometry, University of California, Berkeley, California 94720-2020, USA
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103
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Kuwata H, Fujimoto C, Yoda E, Shimbara S, Nakatani Y, Hara S, Murakami M, Kudo I. A novel role of group VIB calcium-independent phospholipase A2 (iPLA2gamma) in the inducible expression of group IIA secretory PLA2 in rat fibroblastic cells. J Biol Chem 2007; 282:20124-32. [PMID: 17475622 DOI: 10.1074/jbc.m611883200] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Group IIA secretory phospholipase A(2) (sPLA(2)-IIA) is a prototypic sPLA(2) enzyme that may play roles in modification of eicosanoid biosynthesis as well as antibacterial defense. In several cell types, inducible expression of sPLA(2) by pro-inflammatory stimuli is attenuated by group IVA cytosolic PLA(2) (cPLA(2)alpha) inhibitors such as arachidonyl trifluoromethyl ketone, leading to the proposal that prior activation of cPLA(2)alpha is required for de novo induction of sPLA(2). However, because of the broad specificity of several cPLA(2)alpha inhibitors used so far, a more comprehensive approach is needed to evaluate the relevance of this ambiguous pathway. Here, we provide evidence that the induction of sPLA(2)-IIA by pro-inflammatory stimuli requires group VIB calcium-independent PLA(2) (iPLA(2)gamma), rather than cPLA(2)alpha, in rat fibroblastic 3Y1 cells. Results with small interfering RNA unexpectedly showed that the cytokine induction of sPLA(2)-IIA in cPLA(2)alpha knockdown cells, in which cPLA(2)alpha protein was undetectable, was similar to that in replicate control cells. By contrast, knockdown of iPLA(2)gamma, another arachidonyl trifluoromethyl ketone-sensitive intracellular PLA(2), markedly reduced the cytokine-induced expression of sPLA(2)-IIA. Supporting this finding, the R-enantiomer of bromoenol lactone, an iPLA(2)gamma inhibitor, suppressed the cytokine-induced sPLA(2)-IIA expression, whereas (S)-bromoenol lactone, an iPLA(2)beta inhibitor, failed to do so. Moreover, lipopolysaccharide-stimulated sPLA(2)-IIA expression was also abolished by knockdown of iPLA(2)gamma. These findings open new insight into a novel regulatory role of iPLA(2)gamma in stimulus-coupled sPLA(2)-IIA expression.
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Affiliation(s)
- Hiroshi Kuwata
- Department of Health Chemistry, School of Pharmaceutical Sciences, Showa University, 1-5-8 Hatanodai, Shinagawa-ku, Tokyo 142-8555
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104
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Wang M, Liu LH, Wang S, Li X, Lu X, Gupta D, Dziarski R. Human peptidoglycan recognition proteins require zinc to kill both gram-positive and gram-negative bacteria and are synergistic with antibacterial peptides. THE JOURNAL OF IMMUNOLOGY 2007; 178:3116-25. [PMID: 17312159 DOI: 10.4049/jimmunol.178.5.3116] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Mammals have four peptidoglycan recognition proteins (PGRPs or PGLYRPs), which are secreted innate immunity pattern recognition molecules with effector functions. In this study, we demonstrate that human PGLYRP-1, PGLYRP-3, PGLYRP-4, and PGLYRP-3:4 have Zn(2+)-dependent bactericidal activity against both Gram-positive and Gram-negative bacteria at physiologic Zn(2+) concentrations found in serum, sweat, saliva, and other body fluids. The requirement for Zn(2+) can only be partially replaced by Ca(2+) for killing of Gram-positive bacteria but not for killing of Gram-negative bacteria. The bactericidal activity of PGLYRPs is salt insensitive and requires N-glycosylation of PGLYRPs. The LD(99) of PGLYRPs for Gram-positive and Gram-negative bacteria is 0.3-1.7 muM, and killing of bacteria by PGLYRPs, in contrast to killing by antibacterial peptides, does not involve permeabilization of cytoplasmic membrane. PGLYRPs and antibacterial peptides (phospholipase A(2), alpha- and beta-defensins, and bactericidal permeability-increasing protein), at subbactericidal concentrations, synergistically kill Gram-positive and Gram-negative bacteria. These results demonstrate that PGLYRPs are a novel class of recognition and effector molecules with broad Zn(2+)-dependent bactericidal activity against both Gram-positive and Gram-negative bacteria that are synergistic with antibacterial peptides.
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Affiliation(s)
- Minhui Wang
- Indiana University School of Medicine, Northwest Campus, 3400 Broadway, Gary, IN 46408, USA
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105
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Royet J, Dziarski R. Peptidoglycan recognition proteins: pleiotropic sensors and effectors of antimicrobial defences. Nat Rev Microbiol 2007; 5:264-77. [PMID: 17363965 DOI: 10.1038/nrmicro1620] [Citation(s) in RCA: 281] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Peptidoglycan recognition proteins (PGRPs) are innate immunity molecules that are present in most invertebrate and vertebrate animals. All PGRPs function in antimicrobial defence and are homologous to the prokaryotic peptidoglycan-lytic type 2 amidases. However, only some PGRPs have the catalytic activity that protects the host from excessive inflammation, and most PGRPs have diversified to carry out other host-defence functions. Insect and mammalian PGRPs defend host cells against infection through very different mechanisms. Insect PGRPs activate signal transduction pathways in host cells or trigger proteolytic cascades in the haemolymph, both of which generate antimicrobial effectors. By contrast, mammalian PGRPs are directly bactericidal. Here, we review these contrasting modes of action.
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Affiliation(s)
- Julien Royet
- Institut de Biologie du Développement de Marseille-Luminy, UMR 6216 CNRS, Université de la Méditérannée Aix-Marseille II, Marseille, France.
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106
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Belinsky GS, Rajan TV, Saria EA, Giardina C, Rosenberg DW. Expression of secretory phospholipase A2 in colon tumor cells potentiates tumor growth. Mol Carcinog 2007; 46:106-16. [PMID: 17091473 DOI: 10.1002/mc.20271] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Secretory phospholipase A2 (sPLA2-IIA) has been shown to attenuate intestinal tumorigenesis in Apc(Min) mice, demonstrating that it is a tumor modifier. To further explore the actions of sPLA2-IIA in tumorigenesis, sPLA2-IIA was overexpressed in two cell lines where it is normally absent, the murine colon tumor cell line AJ02nm0, and human colon carcinoma cell line HCT-116. Two allelic variants of sPLA2-IIA were tested in this study; sPLA2-IIA(AKR) and sPLA2-IIA(SWR), which are derived from AKR/J and SWR/J mice, respectively, and differ by a single amino acid at position 63 in the calcium- and receptor-binding domain. There was no change in cell-doubling time for either allele when compared to vector controls. Furthermore, sodium butyrate and arachidonic acid (AA)-induced cell death were unchanged in control and transfected cells. Addition of the sPLA2 substrate, palmitoyl-arachidonoyl-phosphatidic acid (PAPA), to AJ02nm0 cells resulted in a modest (12%-24%), but significant (P < 0.01), inhibition of growth that was dependent on sPLA2-IIA expression. However, when AJ02nm0 and HCT-116 cells were injected subcutaneously (sc) into nude mice, Pla2g2a expression resulted in a 2.5-fold increase in tumor size. In addition, sPLA2-IIA expressing HCT-116 tumors were found to be more infiltrative than controls. We conclude that the ability of sPLA2-IIA to slow tumor cell growth is dependent upon the availability of substrate, and that in some instances sPLA2-IIA may actually enhance tumor growth. Mechanisms that may account for differences between the tumor explant model versus the Apc(Min) model of intestinal cancer are discussed.
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Affiliation(s)
- Glenn S Belinsky
- Center for Molecular Medicine, The Neag Comprehensive Cancer Center, University of Connecticut Health Center, Farmington, Connecticut 06030-3101, USA
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107
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Aristoteli LP, Willcox MDP. The adhesion of Pseudomonas aeruginosa to high molecular weight human tear film species corresponds to glycoproteins reactive with Sambucus nigra lectin. Exp Eye Res 2006; 83:1146-53. [PMID: 16844114 DOI: 10.1016/j.exer.2006.06.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2005] [Revised: 06/05/2006] [Accepted: 06/07/2006] [Indexed: 11/27/2022]
Abstract
Pseudomonas aeruginosa is a pathogen gaining prevalence in contact lens-related corneal ulcers. Tear outflow protects the ocular surface, where high molecular weight tear glycoproteins bind bacteria for removal from the eye. The purpose of the present study was to identify glycoproteins in human tears involved in the adhesion of ocular P. aeruginosa isolates. Basal human tears were applied to a bacterial adhesion assay involving electrophoretic separation of tear components, transfer to nitrocellulose and incubation with biotin-labelled bacteria. Glycoproteins were further characterised using lectin profiling. The results showed large-dimension agarose gels were imperative for the detection of at least four glycoproteins with a migration >200 kDa, including species not previously identified. P. aeruginosa 6294 preferentially bound to a well-defined glycoprotein near the origin of the gel that, unlike other glycoproteins >200 kDa, reacted with Sambucus nigra lectin (sialic acid alpha2-6) but not WGA lectin (N-acetylglucosamine, sialic acid alpha2-3). Adhesion did not involve free biotin label or hydrophobic interactions. Also, the pre-incubation of separated tear glycoproteins with S. nigra lectin increased subsequent adhesion of 6294 to this tear glycoprotein. The less virulent Paer1 strain showed diffuse adhesion in the S. nigra-reactive region at the gel origin. In conclusion, an overlay adhesion assay was developed that identified slow-migrating sialylated glycoprotein species in human tears preferentially bound by P. aeruginosa ocular strains, and S. nigra lectin seemed to enhance the interaction. The study provides a basis for direct investigation of bacterial adhesion to glycoproteins with an apparent migration >200 kDa in tear fluid.
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Affiliation(s)
- Lina Panayiota Aristoteli
- Cooperative Research Centre for Eye Research and Technology, The University of New South Wales, Sydney NSW 2052, Australia.
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108
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Brueseke TJ, Bell JD. A new hat for an old enzyme: Waste management. Biochim Biophys Acta Mol Cell Biol Lipids 2006; 1761:1270-9. [PMID: 16828338 DOI: 10.1016/j.bbalip.2006.05.012] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2006] [Revised: 05/19/2006] [Accepted: 05/24/2006] [Indexed: 11/27/2022]
Abstract
The history of research regarding secretory phospholipase A(2) (sPLA(2)) has often focused in one of two directions. Originally, the enzyme was studied biophysically in terms of its fundamental structure, enzymology, and the relationship between membrane physics and catalytic activity. More recently, a large and growing body of information has accumulated concerning regulatory factors, tissue distribution, and physiological/pathological roles of sPLA(2). Evidence is presented that suggests an additional function for the protein in which it helps to clear dead and damaged cells while avoiding digestion of those that are healthy. Apparently, the ability of the enzyme to discriminate between susceptible and resistant cells depends on physical properties of membrane lipids related to order, distribution, and neighbor/neighbor interactions. Investigations into this action of the enzyme offer the rare opportunity to apply biophysical approaches and principles to a physiological setting.
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Affiliation(s)
- Taylor J Brueseke
- Department of Physiology and Developmental Biology, College of Biology and Agriculture, 302C WIDB, Brigham Young University, Provo, UT 84602, USA
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109
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Abstract
Acanthamoeba is an opportunistic protozoan that is widely distributed in the environment and is well recognized to produce serious human infections, including a blinding keratitis and a fatal encephalitis. This review presents our current understanding of the burden of Acanthamoeba infections on human health, their pathogenesis and pathophysiology, and molecular mechanisms associated with the disease, as well as virulence traits of Acanthamoeba that may be targets for therapeutic interventions and/or the development of preventative measures.
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Affiliation(s)
- Naveed Ahmed Khan
- School of Biological and Chemical Sciences, Birkbeck College, University of London, London, UK.
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110
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Yedgar S, Cohen Y, Shoseyov D. Control of phospholipase A2 activities for the treatment of inflammatory conditions. Biochim Biophys Acta Mol Cell Biol Lipids 2006; 1761:1373-82. [PMID: 16978919 DOI: 10.1016/j.bbalip.2006.08.003] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2006] [Accepted: 08/01/2006] [Indexed: 01/10/2023]
Abstract
Phospholipase-A2 (PLA2) enzymes hydrolyze cell membrane phospholipids to produce arachidonic acid (AA) and lyso-phospholipids (LysoPL), playing a key role in the production of inflammatory lipid mediators, mainly eicosanoids. They are therefore considered pro-inflammatory enzymes and their inhibition has long been recognized as a desirable therapeutic target. However, attempts to develop suitable PLA2 inhibitors for the treatment of inflammatory diseases have yet to succeed. This is due to their functional and structural diversity, and their homeostatic and even anti-inflammatory roles in certain circumstances. In the present review we outline the diversity and functions of PLA2 isoforms, and their interplay in the induction and inhibition of inflammatory processes, with emphasis on discussing approaches for therapeutic manipulation of PLA2 activities.
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Affiliation(s)
- Saul Yedgar
- Department of Biochemistry, Hebrew University-Hadassah Medical School, Jerusalem 91120, Israel.
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111
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Zhou L, Beuerman RW, Foo Y, Liu S, Ang LPK, Tan DTH. Characterisation of Human Tear Proteins Using High-resolution Mass Spectrometry. ANNALS OF THE ACADEMY OF MEDICINE, SINGAPORE 2006. [DOI: 10.47102/annals-acadmedsg.v35n6p400] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/05/2023]
Abstract
Introduction: The proteins found in tears play an important role in maintaining the ocular surface and changes in tear protein components may reflect changes in the health of the ocular surface. Proteomics provides a comprehensive approach for cataloguing all the proteins of the tear proteome, which will help to elucidate disease pathogenesis, make clinical diagnoses and evaluate the influence of medications on the structure, composition and secretion of tear proteins. In this study, an alternative proteomic strategy was investigated to explore the human tear proteome.
Materials and Methods: Tear samples were obtained from patients who had pterygium and were collected on the first day and third day after pterygium surgery. Tears pooled from 6 patients were used in the analysis. Reverse-phase high-pressure liquid chromatograph (RP-HPLC) was used as the first step to separate intact proteins into 21 peaks. Each fraction was then tryptic-digested and analysed by nanoLC-nano-ESI-MS/MS to characterise the protein components in each fraction.
Results: In total, 60 tear proteins were identified with high confidence, including well-known abundant tear proteins, and tear-specific proteins such as lacritin and proline-rich proteins. Among them, proline-rich protein 5 was found for the first time in tear fluid. A large number of plasma proteins were also observed in tear fluid.
Conclusions: The results showed that the proteomic strategy used in this study was successfully applied to analyse tear proteome.
Key words: Human tear proteins, Human tear proteome, NanoLC-nanoESI-MS/MS, Tear proteomics
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Affiliation(s)
- Lei Zhou
- Singapore Eye Research Institute, Singapore
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112
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Hunt CL, Nauseef WM, Weiss JP. Effect of d-Alanylation of (Lipo)Teichoic Acids ofStaphylococcus aureuson Host Secretory Phospholipase A2Action before and after Phagocytosis by Human Neutrophils. THE JOURNAL OF IMMUNOLOGY 2006; 176:4987-94. [PMID: 16585595 DOI: 10.4049/jimmunol.176.8.4987] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Invading bacteria such as Staphylococcus aureus induce mobilization of professional phagocytes (e.g., neutrophils) and extracellular antibacterial proteins (e.g., group IIA phospholipase A2 (gIIA PLA2)). Accumulation of gIIA PLA2 in inflammatory fluids confers potent extracellular antistaphylococcal activity and at lower concentrations promotes bacterial phospholipid degradation during phagocytosis of S. aureus by human neutrophils. D-alanylation of (lipo) teichoic acids of S. aureus increases bacterial resistance to gIIA PLA2 approximately 100-fold, raising the possibility that the resistance of ingested S. aureus to related gV and gX secretory PLA2 present in human neutrophil granules depends on D-alanylation mediated by the dlt operon. However, we show that isogenic wild-type and dltA S. aureus are equally resistant to gV/X PLA2 during phagocytosis and when exposed to the purified enzymes. The fates of wild-type and dltA S. aureus exposed to serum and human neutrophils differed significantly only when extracellular gIIA PLA2 was also present before phagocytosis. The extreme potency of the gIIA PLA2 toward dltA S. aureus suggests that even small amounts of this extracellular enzyme mobilized early in inflammation could contribute substantially to the overall cytotoxicity of acute inflammatory exudates toward S. aureus when D-alanylation of (lipo)teichoic acids is limiting.
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Affiliation(s)
- Catherine L Hunt
- The Inflammation Program, University of Iowa and Veterans Affairs Medical Center, Iowa City 52242, USA
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113
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Golik M, Cohen-Zinder M, Loor JJ, Drackley JK, Band MR, Lewin HA, Weller JI, Ron M, Seroussi E. Accelerated expansion of group IID-like phospholipase A2 genes in Bos taurus. Genomics 2006; 87:527-33. [PMID: 16469480 DOI: 10.1016/j.ygeno.2005.12.015] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2005] [Revised: 12/21/2005] [Accepted: 12/21/2005] [Indexed: 10/25/2022]
Abstract
Low-molecular-weight, calcium-dependent phospholipase A2 genes (PLA2s) that belong to the secreted type of PLA2s are clustered within a syntenic group on human 1p35-p36 and mouse 4qD3. We reassembled trace files available from the Whole Genome Sequencing (WGS) Project, obtaining an 86-kb contig with three tandem PLA2G2D duplications in the Hereford strain. We used mate-pair data to monitor the assembly and to exclude chimeric clones, demonstrating that the current WGS data may be assembled even in a highly repetitive region with a coverage exceeding fivefold. The genomic structure indicated that most of the PLA2G2D transcripts are formed by four exons. Two alternative first exons were present in all duplications. In two duplications insertions of satellite DNA in the third intron created a novel exon that gave rise to a two-exon product. Linkage and comparative mapping placed the bovine PLA2G2 locus on BTA2, indicating that it evolved from an ancestral PLA2G2D locus common to human, cattle, and rodents. Bovine PLA2G2D variants were capable of encoding 147-amino-acid polypeptides that consisted of putative signal peptide and metal-binding domains. Cysteine residues were conserved in positions analogous to those forming the seven disulfide bonds characteristic of PLA2G2 genes. Quantitative PCR analysis of bovine PLA2G2D transcripts indicated that their expression levels varied between the dry period and lactation in the mammary gland samples and that their expression was polymorphic in liver tissue. The recent burst of duplication and divergence of the bovine PLA2G2D genes and their polymorphic nature are typical of innate immune response genes.
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Affiliation(s)
- Marina Golik
- Institute of Animal Sciences, Agricultural Research Organization, The Volcani Center, Bet Dagan 50250, Israel
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114
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Menschikowski M, Hagelgans A, Siegert G. Secretory phospholipase A2 of group IIA: Is it an offensive or a defensive player during atherosclerosis and other inflammatory diseases? Prostaglandins Other Lipid Mediat 2006; 79:1-33. [PMID: 16516807 DOI: 10.1016/j.prostaglandins.2005.10.005] [Citation(s) in RCA: 98] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2005] [Revised: 10/29/2005] [Accepted: 10/31/2005] [Indexed: 02/07/2023]
Abstract
Since its discovery in the serum of patients with severe inflammation and in rheumatoid arthritic fluids, the secretory phospholipase A2 of group IIA (sPLA2-IIA) has been chiefly considered as a proinflammatory enzyme, the result of which has been very intense interest in selective inhibitors of sPLA2-IIA in the hope of developing new and efficient therapies for inflammatory diseases. The recent discovery of the antibacterial properties of sPLA2-IIA, however, has raised the question of whether the upregulation of sPLA2-IIA during inflammation is to be considered uniformly negative and the hindrance of sPLA2-IIA in every instance beneficial. The aim of this review is for this reason, along with the results of various investigations which argue for the proinflammatory and proatherogenic effects of an upregulation of sPLA2-IIA, also to array data alongside which point to a protective function of sPLA2-IIA during inflammation. Thus, it could be shown that sPLA2-IIA, apart from the bactericidal effects, possesses also antithrombotic properties and indeed plays a possible role in the resolution of inflammation and the accelerated clearance of oxidatively modified lipoproteins during inflammation via the liver and adrenals. Based on these multipotent properties the knowledge of the function of sPLA2-IIA during inflammation is a fundamental prerequisite for the development and establishment of new therapeutic strategies to prevent and treat severe inflammatory diseases up to and including sepsis.
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Affiliation(s)
- Mario Menschikowski
- Technische Universität Dresden, Medizinische Fakultät Carl Gustav Carus, Institut für Klinische Chemie and Laboratoriumsmedizin, Fetscherstrasse 74, D-01307 Dresden, Germany.
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115
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Hori Y, Spurr-Michaud SJ, Russo CL, Argüeso P, Gipson IK. Effect of retinoic acid on gene expression in human conjunctival epithelium: secretory phospholipase A2 mediates retinoic acid induction of MUC16. Invest Ophthalmol Vis Sci 2005; 46:4050-61. [PMID: 16249480 PMCID: PMC1473963 DOI: 10.1167/iovs.05-0627] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
PURPOSE How vitamin A contributes to the maintenance of the wet-surfaced phenotype at the ocular surface is not well understood. This study sought to identify vitamin A-responsive genes in ocular surface epithelia using gene microarray analysis of cultures of a human conjunctival epithelial (HCjE) cell line grown with all-trans-retinoic acid (RA). The analysis showed that secretory phospholipase A(2) group IIA (sPLA(2)-IIA) was the gene most upregulated by RA, followed by the membrane-associated mucin MUC16 at a later time point. Since eicosanoids, the product of arachidonic acid generated by the PLA(2) family, have been shown to increase mucin production, this study sought to determine whether sPLA(2) mediates the RA induction of MUC16. METHODS HCjE cells were cultured with or without RA for 3, 6, 24, and 48 hours. Complementary RNA prepared from RNA of the HCjE cells was hybridized to human gene chips and analyzed using commercial software. Microarray data on mucin expression were validated by real-time PCR. To investigate whether sPLA(2) is associated with RA-induced MUC16 upregulation, HCjE cells were incubated with RA and the broad-spectrum PLA(2) inhibitor aristolochic acid (ArA) or the specific sPLA(2)-IIA inhibitor LY315920, followed by analysis of MUC16 mRNA and protein by real-time PCR and Western blot analysis. RESULTS After RA addition, 28 transcripts were upregulated and 6 downregulated by more than twofold (P < 0.01) at both 3 and 6 hours (early phase). Eighty gene transcripts were upregulated and 45 downregulated at both 24 and 48 hours (late phase). Group IIA sPLA(2), significantly upregulated by 24 hours, and MUC16 were the most upregulated RNAs by RA at 48 hours. sPLA(2) upregulation by RA was confirmed by Western blot analysis. When HCjE cells were incubated with RA plus ArA or specific inhibitor of sPLA(2)-IIA, LY315920, the RA-induced MUC16 mRNA was significantly reduced (P < 0.01). CONCLUSIONS The RA-associated upregulation of membrane-associated mucin MUC16 at late phase appears to be through sPLA(2)-IIA. Upregulation of this hydrophilic membrane-associated mucin may be one of the important mechanisms by which vitamin A facilitates maintenance of the wet-surfaced phenotype on the ocular surface.
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Affiliation(s)
- Yuichi Hori
- Schepens Eye Research Institute and the Department of Ophthalmology, Harvard Medical School, Boston, MA 02114, USA
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116
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Femling JK, Nauseef WM, Weiss JP. Synergy between extracellular group IIA phospholipase A2 and phagocyte NADPH oxidase in digestion of phospholipids of Staphylococcus aureus ingested by human neutrophils. THE JOURNAL OF IMMUNOLOGY 2005; 175:4653-61. [PMID: 16177112 DOI: 10.4049/jimmunol.175.7.4653] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Acute inflammatory responses to invading bacteria such as Staphylococcus aureus include mobilization of polymorphonuclear leukocytes (PMN) and extracellular group IIA phospholipase A2 (gIIA-PLA2). Although accumulating coincidentally, the in vitro anti-staphylococcal activities of PMN and gIIA-PLA2 have thus far been studied separately. We now show that degradation of S. aureus phospholipids during and after phagocytosis by human PMN requires the presence of extracellular gIIA-PLA2. The concentration of extracellular gIIA-PLA2 required to produce bacterial digestion was reduced 10-fold by PMN. The effects of added gIIA-PLA2 were greater when present before phagocytosis but even apparent when added after S. aureus were ingested by PMN. Related group V and X PLA2, which are present within PMN granules, do not contribute to bacterial phospholipid degradation during and after phagocytosis even when added at concentrations 30-fold higher than that needed for action of the gIIA-PLA2. The action of added gIIA-PLA2 required catalytically active gIIA-PLA2 and, in PMN, a functional NADPH oxidase but not myeloperoxidase. These findings reveal a novel collaboration between cellular oxygen-dependent and extracellular oxygen-independent host defense systems that may be important in the ultimate resolution of S. aureus infections.
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Affiliation(s)
- Jon K Femling
- The Inflammation Program, University of Iowa and Veterans Affairs Medical Center, Iowa City 52242, USA
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117
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Varoga D, Pufe T, Mentlein R, Kohrs S, Grohmann S, Tillmann B, Hassenpflug J, Paulsen F. Expression and regulation of antimicrobial peptides in articular joints. Ann Anat 2005; 187:499-508. [PMID: 16320829 DOI: 10.1016/j.aanat.2005.03.004] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Articular joint infection is a surprisingly rare event considering the frequency of joint arthrocentesis and other invasive procedures applied to limb joints. This observation led us to the hypothesis that a local "chemical shield" in the form of antimicrobial proteins provides synovial membrane and articular cartilage with resistance to infection. We subsequently began a systematic analysis of in vitro and in vivo antimicrobially active proteins in healthy articular joints and in disease states such as pyogenic arthritis, rheumatoid arthritis, and osteoarthritis. An anatomical approach with systematic characterization combined with antimicrobial testing revealed expression and production of human antibiotic peptides and proteins. In this review, we focus on the most prominent antimicrobial proteins in articular joints, which we have identified as lysozyme, lactoferrin, secretory phospholipase A2, RNase 7, CAP37, the cathelicidin LL37, and especially the human beta-defensin-2 and -3 (HBD-2/-3). Activation pathways and possible antimicrobial functions are discussed and the involvement in non-antimicrobial processes such as tissue remodelling is also considered.
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Affiliation(s)
- Deike Varoga
- Department of Orthopaedic Surgery, University Hospital of Schleswig-Holstein, Campus Kiel, Michaelisstrasse 1, 24105 Kiel, Germany.
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Schumann A, Nutten S, Donnicola D, Comelli EM, Mansourian R, Cherbut C, Corthesy-Theulaz I, Garcia-Rodenas C. Neonatal antibiotic treatment alters gastrointestinal tract developmental gene expression and intestinal barrier transcriptome. Physiol Genomics 2005; 23:235-45. [PMID: 16131529 DOI: 10.1152/physiolgenomics.00057.2005] [Citation(s) in RCA: 118] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The postnatal maturation of the gut, partially modulated by bacterial colonization, ends up in the establishment of an efficient barrier to luminal antigens and bacteria. The use of broad-spectrum antibiotics in pediatric practices alters the gut bacterial colonization and, consequently, may impair the maturation of the gut barrier function. To test this hypothesis, suckling Sprague-Dawley rats received a daily intragastric gavage of antibiotic (Clamoxyl; an amoxicillin-based commercial preparation) or saline solution from postnatal day 7 (d7) until d17 or d21. Luminal microbiota composition and global gene expression profile were analyzed on samples from small intestine and colon of each group. The treatment with Clamoxyl resulted in the almost-complete eradication of Lactobacillus in the whole intestine and in a drastic reduction of colonic total aerobic and anaerobic bacteria, in particular Enterobacteriacae and Enterococcus. The global gene expression analysis revealed that Clamoxyl affects the maturation process of 249 and 149 Affymetrix probe sets in the proximal and distal small intestine, respectively, and 163 probe sets in the colon. The expression of genes coding for Paneth cell products (defensins, matrilysin, and phospholipase A2) was significantly downregulated by the Clamoxyl treatment. A significant downregulation of major histocompatibility complex (MHC) class Ib and II genes, involved in antigen presentation, was also observed. Conversely, mast cell proteases expression was upregulated. These results suggest that early treatment with a large-spectrum antibiotic deeply affects the gut barrier function at the suckling-weaning interface, a period during which the gut is challenged by an array of novel food-borne antigens.
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Affiliation(s)
- Alexandra Schumann
- Department of Nutrition and Health, Nestle Research Center, Vers-chez-les-Blanc, Lausanne, Switzerland
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Grönroos JO, Salonen JH, Viander M, Nevalainen TJ, Laine VJO. Roles of Group IIA Phospholipase A2 and Complement in Killing of Bacteria by Acute Phase Serum. Scand J Immunol 2005; 62:413-9. [PMID: 16253130 DOI: 10.1111/j.1365-3083.2005.01678.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The complement system is regarded as an important component of the innate defence system against invading bacteria. However, synergistic actions between the complement and the other components of innate immunity are incompletely known. Human group IIA phospholipase A(2) (hGIIA PLA(2)) is an effective antibacterial enzyme in serum of patients with severe bacterial infections. Our aim was to investigate the significance of complement and hGIIA PLA(2) in acute phase serum. Serum samples were collected from patients with acute bacterial infections and from healthy control subjects. We prepared hGIIA PLA(2)-depleted serum by immunoadsorption and inhibited the activity of complement by a specific inhibitor, compstatin. The bactericidal effects of treated and untreated serum were compared by incubating Staphylococcus aureus and Listeria monocytogenes in the presence of serum. Acute phase serum effectively killed S. aureus and L. monocytogenes, and depletion of hGIIA PLA(2) significantly reduced the antibacterial effect. Complement had a weak bactericidal effect against L. monocytogenes. We conclude that hGIIA PLA(2) is the major antibacterial factor in human acute phase serum against the gram-positive bacteria S. aureus and L. monocytogenes, exceeding complement in efficiency.
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Affiliation(s)
- J O Grönroos
- Department of Pathology, University of Turku, Finland.
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120
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Shen B, Porter EM, Reynoso E, Shen C, Ghosh D, Connor JT, Drazba J, Rho HK, Gramlich TL, Li R, Ormsby AH, Sy MS, Ganz T, Bevins CL. Human defensin 5 expression in intestinal metaplasia of the upper gastrointestinal tract. J Clin Pathol 2005; 58:687-94. [PMID: 15976333 PMCID: PMC1770712 DOI: 10.1136/jcp.2004.022426] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
BACKGROUND Upper gastrointestinal tract intestinal metaplasia (IM) is termed Barrett's oesophagus (BO) or gastric intestinal metaplasia (GIM), depending on its location. BO and GIM are associated with chemical exposure resulting from gastro-oesophageal reflux and chronic Helicobacter pylori infection, respectively. Paneth cells (PCs), characterised by cytoplasmic eosinophilic granules, are found in a subset of IM at these sites, but histology may not accurately detect them. AIM To determine human defensin 5 (HD5; an antimicrobial peptide produced by PCs) expression in BO and GIM, and to investigate its association with H pylori infection. METHODS Endoscopic biopsies from 33 patients with BO and 51 with GIM, and control tissues, were examined by routine histology and for H pylori infection and HD5 mRNA and protein expression. RESULTS In normal tissues, HD5 expression was specific for PCs in the small intestine. Five patients with BE and 42 with GIM expressed HD5, but few HD5 expressing cells in IM had the characteristic histological features of PCs. Most HD5 positive specimens were H pylori infected and most HD5 negative specimens were not infected. CONCLUSIONS HD5 immunohistochemistry was often positive in IM when PCs were absent by conventional histology. Thus, HD5 immunohistochemistry may be superior to histology for identifying metaplastic PCs and distinguishing GIM from BO. The higher frequency of HD5 expression in GIM than in BO is associated with a higher frequency of H pylori infection, suggesting that in IM PCs may form part of the mucosal antibacterial response.
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Affiliation(s)
- B Shen
- Department of Gastroenterology and Hepatology, The Cleveland Clinic Foundation, 9500 Euclid Avenue, Cleveland, OH 44195, USA
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Peuravuori H, Aho VV, Aho HJ, Collan Y, Saari KM. Bactericidal/permeability-increasing protein in lacrimal gland and in tears of healthy subjects. Graefes Arch Clin Exp Ophthalmol 2005; 244:143-8. [PMID: 16044323 DOI: 10.1007/s00417-005-0062-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2004] [Revised: 04/15/2005] [Accepted: 05/17/2005] [Indexed: 10/25/2022] Open
Abstract
BACKGROUND To determine the expression of bactericidal/permeability-increasing protein (BPI), a novel antimicrobial molecule, in the main lacrimal gland and its content in tears of young healthy subjects. METHODS BPI concentration of tears was measured in 42 healthy volunteers, 13 men and 29 women, with ages ranging from 22 to 30 (mean 24.7+/-2.1) years by a time-resolved fluoroimmunoassay (TR-FIA). Immunohistochemical analysis was made to localize BPI in lacrimal gland and conjunctiva of eight autopsied subjects, two men and six women, with the age range from 44 to 87 (mean 72.3+/-14.9) years. RESULT The mean concentration of BPI in tears was 27.8+/-29.5 microg/l, and it decreased with an increase in tear flow rate (P<0.0001). There was no statistically significant difference in BPI content of tears between the genders. BPI was immunohistochemically seen in outer basal epithelial cells of intralobular and excretory ducts, squamous and basal cells of conjunctiva as well as faintly in myoepithelial cell layer of acini. The presence of BPI in the lacrimal gland and in the tear fluid was verified by Western blotting. CONCLUSIONS The results indicate that outer basal epithelial cells of lacrimal gland ducts contain BPI, which occurs in a relatively high concentration in tears. BPI may have a substantial antibacterial role in human tears.
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Kari O, Aho VV, Peltonen S, Saari JM, Kari M, Määttä M, Collan Y, Saari KM. Group IIA phospholipase A2 concentration of tears in patients with ocular rosacea. ACTA ACUST UNITED AC 2005; 83:483-6. [PMID: 16029275 DOI: 10.1111/j.1600-0420.2005.00495.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
PURPOSE To determine the concentration of group IIA phospholipase A(2) (GIIAPLA(2)) in tears of patients with ocular rosacea, and to compare it with GIIAPLA(2) concentration in tears of age-matched healthy controls. METHODS The GIIAPLA(2) concentration in tears was measured with a time-resolved fluoroimmunoassay in 21 patients with ocular rosacea (mean age 55.6+/-9.2 years) and in 21 normal subjects (mean age 53.4+/-8.2 years). Conjunctival brush cytology was carried out and eosinophils, neutrophils, lymphocytes, squamous epithelial cells, columnar epithelial cells, metaplastic changes and goblet cells were calculated separately. RESULTS The GIIAPLA (2) concentration in tears was statistically significantly lower in patients with ocular rosacea (31.0+/-18.4 microg/ml, p=0.0099) and, more specifically, in patients who had dry eye (25.8+/-15.1 microg/ml, p=0.0034), compared to that in normal controls. There was no correlation between the GIIAPLA (2) content of tears and the conjunctival cells collected by the brush cytology. CONCLUSION The tears of patients with dry eye symptoms due to ocular rosacea have decreased GIIAPLA (2) content. The pathogenic importance of this finding is discussed.
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Affiliation(s)
- Osmo Kari
- Department of Allergology, University of Helsinki, Helsinki, Finland
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123
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Ikeno Y, Konno N, Cheon SH, Bolchi A, Ottonello S, Kitamoto K, Arioka M. Secretory Phospholipases A2 Induce Neurite Outgrowth in PC12 Cells through Lysophosphatidylcholine Generation and Activation of G2A Receptor. J Biol Chem 2005; 280:28044-52. [PMID: 15927955 DOI: 10.1074/jbc.m503343200] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We previously demonstrated that secretory phospholipase A2 (sPLA2) and lysophosphatidylcholine (LPC) exhibit neurotrophin-like neuritogenic activity in the rat pheochromocytoma cell line PC12. In this study, we further analyzed the mechanism whereby sPLA2 displays neurite-inducing activity. Exogenously added mammalian group X sPLA2 (sPLA2-X), but not group IB and IIA sPLA2s, induced neuritogenesis, which correlated with the ability of sPLA2-X to liberate LPC into the culture media. In accordance, blocking the effect of LPC by supplementation of bovine serum albumin or phospholipase B attenuated neuritogenesis by sPLA2 or LPC. Overproduction or suppression of G2A, a G-protein-coupled receptor involved in LPC signaling, resulted in the enhancement or reduction of neuritogenesis induced by sPLA2 treatment. These results indicate that the neuritogenic effect of sPLA2 is mediated by generation of LPC and subsequent activation of G2A.
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Affiliation(s)
- Yutaka Ikeno
- Department of Biotechnology, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
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Santamaría C, Larios S, Quirós S, Pizarro-Cerda J, Gorvel JP, Lomonte B, Moreno E. Bactericidal and antiendotoxic properties of short cationic peptides derived from a snake venom Lys49 phospholipase A2. Antimicrob Agents Chemother 2005; 49:1340-5. [PMID: 15793109 PMCID: PMC1068596 DOI: 10.1128/aac.49.4.1340-1345.2005] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The activities of short synthetic, nonhemolytic peptides derived from the C-terminal region of myotoxin II, a catalytically inactive phospholipase A2 homologue present in the venom of the snake Bothrops asper, have been shown to reproduce the bactericidal activity of the parent protein. They combine cationic and hydrophobic-aromatic amino acids, thus functionally resembling the antimicrobial peptides of innate defenses. This study evaluated the antimicrobial and antiendotoxic properties of a 13-mer derivative peptide of the C-terminal sequence from positions 115 to 129 of myotoxin II, named pEM-2. This peptide (KKWRWWLKALAKK) showed bactericidal activity against both gram-positive and gram-negative bacteria. In comparison to previously described peptide variants derived from myotoxin II, the toxicity of pEM-2 toward eukaryotic cells in culture was significantly reduced, being similar to that of lactoferricin B but lower than that of polymyxin B. The all-D enantiomer of pEM-2 [pEM-2 (D)] retained the same bactericidal potency of its L-enantiomeric counterpart, but it showed an enhanced ability to counteract the lethal activity of an intraperitoneal lipopolysaccharide challenge in mice, which correlated with a significant reduction of the serum tumor necrosis factor alpha levels triggered by this endotoxin. Lethality induced by intraperitoneal infection of mice with Escherichia coli or Salmonella enterica serovar Typhimurium was reduced by the administration of pEM-2 (D). These results demonstrate that phospholipase A2-derived peptides may have the potential to counteract microbial infections and encourage further evaluations of their actions in vivo.
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Affiliation(s)
- Carlos Santamaría
- Instituto Clodomiro Picado, Facultad de Microbiología, Universidad de Costa Rica, San José 2060, Costa Rica
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Nevalainen TJ, Eerola LI, Rintala E, Laine VJO, Lambeau G, Gelb MH. Time-resolved fluoroimmunoassays of the complete set of secreted phospholipases A2 in human serum. Biochim Biophys Acta Mol Cell Biol Lipids 2005; 1733:210-23. [PMID: 15863368 DOI: 10.1016/j.bbalip.2004.12.012] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2004] [Revised: 12/03/2004] [Accepted: 12/20/2004] [Indexed: 11/23/2022]
Abstract
Time-resolved fluoroimmunoassays (TR-FIA) were developed for all human secreted phospholipases A(2) (PLA(2)), viz. group (G) IB, GIIA, GIID, GIIE, GIIF, GIII, GV, GX and GXIIA PLA(2) and the GXIIB PLA(2)-like protein. Antibodies were raised in rabbits against recombinant human PLA(2) proteins and used in sandwich-type TR-FIAs as both catching and detecting antibodies, the latter after labeling with Europium. The antibodies were non-cross-reactive. The analytical sensitivities were 1 microg/L for the TR-FIA for GIB PLA(2), 1 microg/L (GIIA), 35 microg/L (GIID), 3 microg/L (GIIE), 4 microg/L (GIIF), 14 microg/L (GIII), 11 microg/L (GV), 2 microg/L (GX), 92 microg/L (GXIIA) and 242 microg/L (GXIIB). All secreted PLA(2)s were assayed by these TR-FIAs in serum samples from 34 patients (23 men and 11 women, mean age 53.2 years) treated in an intensive care unit for septic infections, and in control samples from 28 volunteer blood donors (14 men and 14 women, mean age 57.0 years). Five serum samples (3 in the sepsis group and 2 in the blood donor group) gave high TR-FIA signals that were reduced to background (blank) levels by the addition of non-immune rabbit IgG to the sera. This reactivity was assumed to be due to the presence of heterophilic antibodies in these subjects. In all other subjects, including septic patients and healthy blood donors, the TR-FIA signals for GIID, GIIE, GIIF, GIII, GV, GX and GXIIA PLA(2) and the GXIIB PLA(2)-like protein were at background (blank) levels. Four patients in the sepsis group had pancreatic involvement and elevated concentration of GIB PLA(2) in serum (median 19.0 microg/L, range 13.1-33.7 microg/L, n = 4) as compared to the healthy blood donors (median 1.8 microg/L, range 0.8-3.4 microg/L, n = 28, P < 0.0001). The concentration of GIIA PLA(2) in the sera of septic patients (median 315.7 microg/L, range 15.9-979.6 microg/L, n = 34) was highly elevated as compared to that of the blood donors (median 1.8 microg/L, range 0.8-5.8 microg/L, n = 28, P < 0.0001). Our current results confirmed elevated concentrations of GIB and GIIA PLA(2) in the sera of patients suffering from acute pancreatitis or septic infections, respectively, as compared to healthy subjects. However, in the same serum samples, the concentrations of the other secreted PLA(2)s, viz. GIID, GIIE, GIIF, GIII, GV, GX and GXIIA PLA(2) and the GXIIB PLA(2)-like protein were below the respective analytical sensitivities of the TR-FIAs. It is concluded that generalized bacterial infections do not lead to elevated serum levels of GIIE, GIIF, GIII, GV and GX PLA(2)s above the detection limits of the current TR-FIAs.
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Villarrubia VG, Costa LA, Díez RA. [Secreted phospholipases A2 (sPLA2): friends or foes? Are they actors in antibacterial and anti-HIV resistance?]. Med Clin (Barc) 2005; 123:749-57. [PMID: 15574291 DOI: 10.1016/s0025-7753(04)74656-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
In this paper the authors update on the deletereous or beneficial roles of human and animal secretory phospholipases A2 (sPLA2). Although human sPLA2-IIA (inflammatory) was initially thought as a foe because its pathogenic implication in sepsis, multiorganic failure or other related syndromes, recent data indicates its role in in the antiinfectious host resistance. Thus, sPLA2-IIA exhibits potent bactericidal activities against gram-negative and gram-positive (in this case, together with other endogenous inflammatory factors) bacteria. Surprisingly, human sPLA-IIA does not show in vitro anti-human immunodeficiency virus (HIV) activity, whilst several sPLA2-IA isolated from bee and serpent venons do it: this is the case for crotoxin, a sPLA2-IA isolated from the venon of Crotalus durissus terrificus (sPLA2-Cdt). The mechanism for the in vitro anti-HIV activity of sPLA2-Cdt (inhibition of Gag p24) appears to be related to the ability of the drug to desestabilize ancorage (heparans) and fusion (cholesterol) receptors on HIV target cells.
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Landreville S, Coulombe S, Carrier P, Gelb MH, Guérin SL, Salesse C. Expression of phospholipases A2 and C in human corneal epithelial cells. Invest Ophthalmol Vis Sci 2004; 45:3997-4003. [PMID: 15505048 PMCID: PMC2424249 DOI: 10.1167/iovs.04-0084] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To achieve a better understanding of the involvement of phospholipases in the inflammation and wound-healing processes in human corneal epithelial cells (HCECs), expression of phospholipase A2s (PLA2s) and phospholipase Cs (PLCs) was examined in the human corneal epithelium. METHODS Specific primers were designed for RT-PCR amplification of the known secreted (s)PLA2, cytosolic (c)PLA2, and PLC mRNAs. Corresponding PCR products were cloned and the DNA sequenced. Immunofluorescence of flatmounted corneal sections and Western blot analyses were used to detect the PLA2s and PLCs expressed by HCECs. RESULTS The mRNAs for the following phospholipases were detected by RT-PCR in the HCECs: sPLA2GIII, -GX, and -GXIIA; cPLA2alpha and -gamma; PLCbeta1, -beta2, -beta3, -beta4, -gamma1, -gamma2, -delta1, -delta3, -delta4, and -epsilon. Immunofluorescence analyses conducted on corneal epithelium cryosections and Western blot on freshly isolated HCECs demonstrated the presence of sPLA2GIII, -GX, and -GXIIA; cPLA2alpha and -gamma; and PLCbeta2, -beta3, -gamma1, -gamma2, and -delta3. CONCLUSIONS Many phospholipase isoforms are expressed by HCECs and may play a major role in signal transduction (PLCs) as well as in the release of precursors of potent mediators of inflammation, such as leukotrienes and prostaglandins (PLA2s). Moreover, the sPLA2s expressed by the corneal epithelium could be involved in the normal antibacterial activity in the tears and in wound healing.
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Affiliation(s)
- Solange Landreville
- Unité de Recherche en Ophtalmologie, Centre de Recherche du Centre Hospitalier Universitaire de Québec (CHUQ), Pavillon du Centre Hospitalier de l’Université Laval (CHUL), Faculté de Médecine
| | - Stéphanie Coulombe
- Unité de Recherche en Ophtalmologie, Centre de Recherche du Centre Hospitalier Universitaire de Québec (CHUQ), Pavillon du Centre Hospitalier de l’Université Laval (CHUL), Faculté de Médecine
| | - Patrick Carrier
- Laboratoire d’Organogenèse Expérimentale, Centre Hospitalier Affilié Universitaire, Pavillon Saint-Sacrement, Université Laval, Sainte-Foy, Québec, Canada
| | - Michael H. Gelb
- Departments of Chemistry and Biochemistry, University of Washington, Seattle, Washington
| | - Sylvain L. Guérin
- Centre de Recherche en Oncologie et Endocrinologie Moléculaire, Centre de Recherche du Centre Hospitalier Universitaire de Québec (CHUQ), Pavillon du Centre Hospitalier de l’Université Laval (CHUL), Faculté de Médecine
| | - Christian Salesse
- Unité de Recherche en Ophtalmologie, Centre de Recherche du Centre Hospitalier Universitaire de Québec (CHUQ), Pavillon du Centre Hospitalier de l’Université Laval (CHUL), Faculté de Médecine
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Abstract
PURPOSE OF REVIEW Innate immune defense of the small intestine is mediated in part by antimicrobial peptides and proteins secreted by Paneth cells, epithelial cells positioned at the base of the crypts of Lieberkuhn. Recent studies have yielded better understanding of the role that Paneth cells may play in host defense. Emerging data suggest that these cells may contribute to the pathophysiology of several human diseases. A wealth of data has also emerged on the regulatory pathways of Paneth cell functions and structure-function analysis on Paneth cell antimicrobials. This review discusses new reports in these areas. RECENT FINDINGS Studies of transgenic and knockout mice have supported a pivotal role of Paneth cell defensins in protection from oral bacterial pathogens. Other studies suggest that Paneth cells may be the targets of virulence mechanisms of bacterial pathogens. New observations also suggest that Paneth cell dysfunction may contribute to the clinical phenotype of Crohn disease, necrotizing enterocolitis, and, perhaps, intestinal manifestations of cystic fibrosis. SUMMARY Paneth cells are emerging as key mediators of innate host defense in the small intestine. The antimicrobial activity of Paneth cell secretory products on transient and resident microbes in the gut may have a profound influence on health. The possible role of Paneth cell dysfunction in human disease and a better understanding of Paneth cell regulatory pathways are areas poised for significant advances in the near future.
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Affiliation(s)
- Charles L Bevins
- The Department of Medical Microbiology and Immunology, School of Medicine, University of California, Davis, California 95616, USA.
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Fluckinger M, Haas H, Merschak P, Glasgow BJ, Redl B. Human tear lipocalin exhibits antimicrobial activity by scavenging microbial siderophores. Antimicrob Agents Chemother 2004; 48:3367-72. [PMID: 15328098 PMCID: PMC514737 DOI: 10.1128/aac.48.9.3367-3372.2004] [Citation(s) in RCA: 147] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Human tear lipocalin (TL; also known as Lcn1) is a secretory protein present in large amounts in fluids that cover epithelial surfaces such as tears and respiratory secretions. It is supposed to act as a physiological scavenger of hydrophobic, potentially harmful molecules, but there is evidence that it also inhibits bacterial growth. In the present study, we reconsidered the possibility that TL might interfere with microbial growth by scavenging of siderophores, as described for human neutrophil gelatinase-associated lipocalin (NGAL). Indeed, our experiments revealed that TL binds to microbial siderophores with high affinities. In contrast to NGAL, which was shown to have some specificity for bacterial catecholate-type siderophores, TL binds to a broad array of siderophores, including bacterial catecholate-type enterobactin and hydroxamate-type desferrioxamine B, and all major classes of fungal siderophores. By adding exogenous TL, bacterial and fungal growth could be inhibited under iron-limiting conditions. Thus, TL might be a novel member of the innate immune system especially involved in mucosal defense against fungal infections.
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Affiliation(s)
- Maria Fluckinger
- Department of Molecular Biology, Innsbruck Medical University, Peter-Mayr Strasse 4b, A-6020 Innsbruck, Austria
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Gimenez AP, Wu YZ, Paya M, Delclaux C, Touqui L, Goossens PL. High bactericidal efficiency of type iia phospholipase A2 against Bacillus anthracis and inhibition of its secretion by the lethal toxin. THE JOURNAL OF IMMUNOLOGY 2004; 173:521-30. [PMID: 15210813 DOI: 10.4049/jimmunol.173.1.521] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
There is a considerable body of evidence supporting the role of secretory type II-A phospholipase A(2) (sPLA(2)-IIA) as an effector of the innate immune response. This enzyme also exhibits bactericidal activity especially toward Gram-positive bacteria. In this study we examined the ability of sPLA(2)-IIA to kill Bacillus anthracis, the etiological agent of anthrax. Our results show that both germinated B. anthracis spores and encapsulated bacilli were sensitive to the bactericidal activity of recombinant sPLA(2)-IIA in vitro. In contrast, nongerminated spores were resistant. This bactericidal effect was correlated to the ability of sPLA(2)-IIA to hydrolyze bacterial membrane phospholipids. Guinea pig alveolar macrophages, the major source of sPLA(2)-IIA in an experimental model of acute lung injury, released enough sPLA(2)-IIA to kill extracellular B. anthracis. The production of sPLA(2)-IIA was significantly inhibited by B. anthracis lethal toxin. Human bronchoalveolar lavage fluids from acute respiratory distress syndrome patients are known to contain sPLA(2)-IIA; bactericidal activity against B. anthracis was detected in a high percentage of these samples. This anthracidal activity was correlated to the levels of sPLA(2)-IIA and was abolished by an sPLA(2)-IIA inhibitor. These results suggest that sPLA(2)-IIA may play a role in innate host defense against B. anthracis infection and that lethal toxin may help the bacteria to escape from the bactericidal action of sPLA(2)-IIA by inhibiting the production of this enzyme.
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Affiliation(s)
- Alejandro Piris Gimenez
- Unité Toxines et Pathogénie Bactérienne/Centre National de la Recherche Scientifique, Institut National de la Santé et de la Recherche Médicale, 25 rue du Dr. Roux, Institut Pasteur, 75724 Paris Cedex 15, France
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Liberty IF, Raichel L, Hazan-Eitan Z, Pessach I, Hadad N, Schlaeffer F, Levy R. Cytosolic phospholipase A2 is responsible for prostaglandin E2 and leukotriene B4 formation in phagocyte-like PLB-985 cells: studies of differentiated cPLA2-deficient PLB-985 cells. J Leukoc Biol 2004; 76:176-84. [PMID: 15123778 DOI: 10.1189/jlb.1003453] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Our previously established model of cytosolic phospholipase A(2) (cPLA(2))-deficient, differentiated PLB-985 cells (PLB-D cells) was used to determine the physiological role of cPLA(2) in eicosanoid production. Parent PLB-985 (PLB) cells and PLB-D cells were differentiated toward the monocyte or granulocyte lineages using 5 x 10(-)(8) M 1,25 dihydroxyvitamin D(3) or 1.25% dimethyl sulfoxide, respectively. Parent monocyte- or granulocyte-like PLB cells released prostaglandin E(2) (PGE(2)) when stimulated by ionomycin, A23187, opsonized zymosan, phorbol 12-myristate 13-acetate, or formyl-Met-Leu-Phe (fMLP), and monocyte- or granulocyte-like PLB-D cells did not release PGE(2) with any of the agonists. The kinetics of cPLA(2) translocation to nuclear fractions in monocyte-like PLB cells stimulated with fMLP or ionomycin was in correlation with the kinetics of PGE(2) production. Granulocyte-like PLB cells, but not granulocyte-like PLB-D cells, secreted leukotriene B(4) (LTB(4)) after stimulation with ionomycin or A23187. Preincubation of monocyte-like parent PLB cells with 100 ng/ml lipopolysaccharide (LPS) for 16 h enhanced stimulated PGE(2) production, which is in correlation with the increased levels of cPLA(2) detected in these cells. LPS preincubation was less potent in increasing PGE(2) and LTB(4) secretion and did not affect cPLA(2) expression in granulocyte-like PLB cells, which may be a result of their lower levels of surface LPS receptor expression. LPS had no effect on monocyte- or granulocyte-like PLB-D cells. The lack of eicosanoid formation in stimulated, differentiated cPLA(2)-deficient PLB cells indicates that cPLA(2) contributes to stimulated eicosanoid formation in monocyte- and granulocyte-like PLB cells.
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Affiliation(s)
- I Furstenberg Liberty
- Department of Clinical Biochemistry, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer Sheva 84105, Israel.
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133
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Canaan S, Zádori Z, Ghomashchi F, Bollinger J, Sadilek M, Moreau ME, Tijssen P, Gelb MH. Interfacial Enzymology of Parvovirus Phospholipases A2. J Biol Chem 2004; 279:14502-8. [PMID: 14726513 DOI: 10.1074/jbc.m312630200] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The capsid of parvoviruses proteins were recently shown to contain secreted phospholipase A(2) (sPLA(2))-like activity that is required during host cell entry. Parvoviral PLA(2) domains have little sequence identity with sPLA(2)s and lack disulfide bonds. In the present study, after bacterial expression and purification, the biochemical characterizations of these first PLA(2)s identified in viruses have been investigated, and a comparison has been made with other known PLA(2)s. The specific activities of three viral PLA(2)s differed by 3 orders of magnitude, with porcine parvovirus PLA(2) displaying a specific activity similar to that of the most active sPLA(2)s (e.g. human group IIA) and the human AAV2 and B19 parvoviral enzymes displaying approximately 10(3) lower specific activities (similar to human sPLA(2) groups IIE and XIIA). These differences were not caused by weaker Ca(2+) or interfacial binding. The specific activities of the viral PLA(2)s on zwitterionic or anionic phospholipid vesicles were comparable. The viral PLA(2)s did not display a preference for unsaturated versus saturated sn-2 fatty acyl chains and hydrolyzed all major classes of glycero-phospholipids except phosphatidylinositol. Incubation of mammalian cells with porcine parvovirus PLA(2) led to the release of arachidonic acid into the culture medium. Interestingly, among nine previously known sPLA(2) inhibitors, only a subset showed inhibition of the viral PLA(2)s and with weak potency, indicating that the active sites of these new enzymes are structurally distinct from those of sPLA(2)s. Based on these distinct enzymatic and structural properties, we propose to classify the parvovirus PLA(2)s within the PLA(2) superfamily as group XIII enzymes.
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Affiliation(s)
- Stéphane Canaan
- Departments of Chemistry and Biochemistry, University of Washington, Seattle, Washington 98195, USA
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134
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Abstract
Mammalian cells have developed specific pathways for the incorporation, remodeling, and release of arachidonic acid. Acyltransferase and transacylase pathways function to regulate the levels of esterified arachidonic acid in specific phospholipid pools. There are several distinct, differentially regulated phospholipases A2in cells that mediate agonist-induced release of arachidonic acid. These pathways are important in controlling cellular levels of free arachidonic acid. Both arachidonic acid and its oxygenated metabolites are potent bioactive mediators that regulate a myriad of physiological and pathophysiological processes.Key words: phospholipase A2, arachidonic acid, eicosanoid, phospholipid.
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Affiliation(s)
- Christina C Leslie
- Department of Pediatrics, National Jewish Medical and Research Center, Denver, CO 80206, USA.
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135
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Aho VV, Holopainen JM, Tervo T, Moilanen JAO, Nevalainen T, Saari KM. Group IIA phospholipase A(2) content in tears of patients having photorefractive keratectomy. J Cataract Refract Surg 2004; 29:2163-7. [PMID: 14670426 DOI: 10.1016/s0886-3350(03)00419-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE To study the effect of photorefractive keratectomy (PRK) on the concentration of group IIA phospholipase A(2) (GIIAPLA(2)) in tears. SETTING Departments of Ophthalmology and Pathology, University of Turku, Turku, and Helsinki University Eye Hospital, Helsinki, Finland. METHODS Tear samples were collected from 25 eyes of 23 patients (mean age 32.3 years +/- 8.6 [SD]) preoperatively and 2 and 7 days after PRK. The GIIAPLA(2) concentration in the tears was measured by time-resolved fluoroimmunoassay. RESULTS The GIIAPLA(2) concentration was significantly lower and the tear fluid flow rate significantly higher 2 days after PRK than preoperatively. At 7 days, the GIIAPLA(2) concentration and the tear fluid flow-corrected excretion of GIIAPLA(2) were significantly higher than preoperatively and at 2 days. The tear flow rate was also significantly higher than preoperatively. CONCLUSIONS The GIIAPLA(2) content in tears decreased 2 days after PRK due to dilution of the GIIAPLA(2) content during hypersecretion of reflex tears. Photorefractive keratectomy caused an increase in the tear flow rate, GIIAPLA(2) concentration, and tear fluid flow-corrected excretion of GIIAPLA(2) in tears 7 days after surgery, enhancing the protection of tears against bacterial infections.
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Affiliation(s)
- Valtteri V Aho
- Department of Ophthalmology, University of Turku, Turku, Finland
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136
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Dubouix A, Campanac C, Fauvel J, Simon MF, Salles JP, Roques C, Chap H, Marty N. Bactericidal properties of group IIa secreted phospholipase A2 against Pseudomonas aeruginosa clinical isolates. J Med Microbiol 2003; 52:1039-1045. [PMID: 14614061 DOI: 10.1099/jmm.0.05303-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
It has been shown that human group IIa secreted phospholipase A(2) (sPLA(2)), found at high levels in inflammatory fluids, displays direct bactericidal properties against Gram-positive bacteria, while activity against Gram-negative bacteria requires the complement system or additional co-factors produced by neutrophils. Pseudomonas aeruginosa, an increasingly prevalent opportunistic human pathogen, is the most common Gram-negative rod found in cystic fibrosis lung infections, where it is associated with an inflammatory environment. Because murine intestinal group II sPLA(2) produced by Paneth cells has been shown to be directly bactericidal against Gram-negative bacteria, IIa sPLA(2) activity against P. aeruginosa clinical isolates was evaluated and provides the first evidence that the enzyme can be fully bactericidal in a concentration- and time-dependent manner against Gram-negative rods. Furthermore, it was demonstrated that these bactericidal properties were unaffected by high protein and salt concentrations, as observed in cystic fibrosis secretions, and that bacterial killing paralleled phospholipid hydrolysis. Finally, no cytotoxicity was observed when IIa sPLA(2) was incubated with human pulmonary cells, highlighting its potential use to synergize bactericidal antibiotics by promoting sublethal alterations of the bacterial cell wall.
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Affiliation(s)
- Anne Dubouix
- INSERM CPTP-U563, CHU Purpan, 1 Place du Dr Baylac, TSA 40031, 31059 Toulouse Cedex 9, France 2,4Laboratoire de Bactériologie-Hygiène2 and INSERM U5834, CHU Rangueil, 1 Avenue Jean Poulhes, TSA 50032, 31059 Toulouse Cedex 9, France 3Laboratoire de Microbiologie, Faculté de Pharmacie, 27 Chemin des Maraîchers, 31400 Toulouse, France
| | - Catherine Campanac
- INSERM CPTP-U563, CHU Purpan, 1 Place du Dr Baylac, TSA 40031, 31059 Toulouse Cedex 9, France 2,4Laboratoire de Bactériologie-Hygiène2 and INSERM U5834, CHU Rangueil, 1 Avenue Jean Poulhes, TSA 50032, 31059 Toulouse Cedex 9, France 3Laboratoire de Microbiologie, Faculté de Pharmacie, 27 Chemin des Maraîchers, 31400 Toulouse, France
| | - Josette Fauvel
- INSERM CPTP-U563, CHU Purpan, 1 Place du Dr Baylac, TSA 40031, 31059 Toulouse Cedex 9, France 2,4Laboratoire de Bactériologie-Hygiène2 and INSERM U5834, CHU Rangueil, 1 Avenue Jean Poulhes, TSA 50032, 31059 Toulouse Cedex 9, France 3Laboratoire de Microbiologie, Faculté de Pharmacie, 27 Chemin des Maraîchers, 31400 Toulouse, France
| | - Marie-Françoise Simon
- INSERM CPTP-U563, CHU Purpan, 1 Place du Dr Baylac, TSA 40031, 31059 Toulouse Cedex 9, France 2,4Laboratoire de Bactériologie-Hygiène2 and INSERM U5834, CHU Rangueil, 1 Avenue Jean Poulhes, TSA 50032, 31059 Toulouse Cedex 9, France 3Laboratoire de Microbiologie, Faculté de Pharmacie, 27 Chemin des Maraîchers, 31400 Toulouse, France
| | - Jean-Pierre Salles
- INSERM CPTP-U563, CHU Purpan, 1 Place du Dr Baylac, TSA 40031, 31059 Toulouse Cedex 9, France 2,4Laboratoire de Bactériologie-Hygiène2 and INSERM U5834, CHU Rangueil, 1 Avenue Jean Poulhes, TSA 50032, 31059 Toulouse Cedex 9, France 3Laboratoire de Microbiologie, Faculté de Pharmacie, 27 Chemin des Maraîchers, 31400 Toulouse, France
| | - Christine Roques
- INSERM CPTP-U563, CHU Purpan, 1 Place du Dr Baylac, TSA 40031, 31059 Toulouse Cedex 9, France 2,4Laboratoire de Bactériologie-Hygiène2 and INSERM U5834, CHU Rangueil, 1 Avenue Jean Poulhes, TSA 50032, 31059 Toulouse Cedex 9, France 3Laboratoire de Microbiologie, Faculté de Pharmacie, 27 Chemin des Maraîchers, 31400 Toulouse, France
| | - Hugues Chap
- INSERM CPTP-U563, CHU Purpan, 1 Place du Dr Baylac, TSA 40031, 31059 Toulouse Cedex 9, France 2,4Laboratoire de Bactériologie-Hygiène2 and INSERM U5834, CHU Rangueil, 1 Avenue Jean Poulhes, TSA 50032, 31059 Toulouse Cedex 9, France 3Laboratoire de Microbiologie, Faculté de Pharmacie, 27 Chemin des Maraîchers, 31400 Toulouse, France
| | - Nicole Marty
- INSERM CPTP-U563, CHU Purpan, 1 Place du Dr Baylac, TSA 40031, 31059 Toulouse Cedex 9, France 2,4Laboratoire de Bactériologie-Hygiène2 and INSERM U5834, CHU Rangueil, 1 Avenue Jean Poulhes, TSA 50032, 31059 Toulouse Cedex 9, France 3Laboratoire de Microbiologie, Faculté de Pharmacie, 27 Chemin des Maraîchers, 31400 Toulouse, France
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137
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Espana EM, Tseng SCG. Analysis of contact lens intolerance by exploring neuroanatomic integration of ocular surface defense. Cont Lens Anterior Eye 2003; 26:131-7. [PMID: 16303508 DOI: 10.1016/s1367-0484(03)00021-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
This paper reviews the anatomic, neuronal and mechanical factors that affect contact lens wear, and outlines several areas where compromised ocular surface defense arising from dysfunctional neuroanatomic integration might be the source of or a contributor to contact lens intolerance. Suggestions for clinical work-up by analyzing neuroanatomic integration are presented as a logical way to dissect this complex problem.
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Affiliation(s)
- Edgar M Espana
- Ocular Surface Center and Ocular Surface Research & Education Foundation, 8780 SW 92 Street, Suite 203, Miami, FL 33176, USA
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138
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Tietge UJF, Maugeais C, Cain W, Rader DJ. Acute inflammation increases selective uptake of HDL cholesteryl esters into adrenals of mice overexpressing human sPLA2. Am J Physiol Endocrinol Metab 2003; 285:E403-11. [PMID: 12637261 DOI: 10.1152/ajpendo.00576.2002] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The acute-phase protein secretory phospholipase A2 (sPLA2) influences the metabolism of high-density lipoproteins (HDL). The adrenals are known to utilize HDL cholesterol as a source of sterols. The aim of the present study was to test the hypothesis that sPLA2 enhances the selective uptake of HDL into the adrenals in response to acute inflammation as a possible physiological role for the sPLA2-HDL interaction. Human sPLA2-transgenic mice, in which sPLA2 expression is upregulated by inflammatory stimuli, were used. Ten hours after induction of the acute-phase response (APR) by injection of bacterial lipopolysaccharide (LPS), plasma levels of HDL cholesterol decreased significantly in sPLA2-transgenic mice (-18%, P < 0.05) but remained unchanged in wild-type mice. The fractional catabolic rates of both 125I-labeled tyraminecellobiose (TC)-HDL and [3H]cholesteryl ether increased significantly in the sPLA2-transgenic mice after induction of the APR (0.18 +/- 0.01 vs. 0.21 +/- 0.01 pool/h, P < 0.05, and 0.31 +/- 0.02 vs. 0.42 +/- 0.05 pool/h, P < 0.05, respectively) but remained unchanged in the wild-type mice (0.10 +/- 0.01 vs. 0.22 +/- 0.02 pool/h, respectively). After induction of the APR, in both groups HDL holoparticle uptake by the liver was increased (P < 0.001). sPLA2-transgenic mice had 2.4-fold higher selective uptake into the adrenals after induction of the APR than wild-type mice (156 +/- 6 vs. 65 +/- 5%/ micro g tissue protein, P < 0.001). In summary, upregulation of sPLA2 expression during the APR specifically increases the selective uptake of HDL cholesteryl ester into the adrenals. These data suggest a novel metabolic role for sPLA2: modification of HDL during the APR to promote increased adrenal uptake of HDL cholesteryl ester to serve as source for steroid hormone synthesis.
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Affiliation(s)
- Uwe J F Tietge
- Univ. of Pennsylvania Medical Center, 654 BRB II/III, 421 Curie Blvd., Philadelphia, PA 19104-6160, USA.
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139
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Abstract
The increasing development of bacterial resistance to traditional antibiotics has reached alarming levels, thus creating a strong need to develop new antimicrobial agents. These new antibiotics should possess novel mechanisms of action and different cellular targets compared with existing antimicrobials. Recent discoveries and isolations of so-called animal antibiotics, mostly small cationic peptides, which represent a potent branch of natural immunity, offered the possibility to acquire new and effective antibiotics of this provenance. To this date, more than 500 antibiotic peptides have been distinguished and defined. Their antimicrobial properties present new opportunities for their use as antibiotics or for construction of their more effective derivatives, but much research is still required to pave the way to their practical use. This is a survey of substances forming an armamentarium of natural immunity of mammals.
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Affiliation(s)
- P Síma
- Division of Immunology and Gnotobiology, Institute of Microbiology, Academy of Sciences of the Czech Republic, 142 20 Prague, Czechia.
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140
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Fleiszig SMJ, Kwong MSF, Evans DJ. Modification of Pseudomonas aeruginosa interactions with corneal epithelial cells by human tear fluid. Infect Immun 2003; 71:3866-74. [PMID: 12819071 PMCID: PMC162005 DOI: 10.1128/iai.71.7.3866-3874.2003] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Both cytotoxic and invasive strains of Pseudomonas aeruginosa can damage corneal epithelial cells in vitro, but neither can infect healthy corneas in vivo. We tested the hypothesis that whole human tear fluid can protect corneal epithelia against P. aeruginosa virulence mechanisms. Cultured corneal epithelial cells were inoculated with 10(6) CFU of one of 10 strains of P. aeruginosa (five cytotoxic, five invasive)/ml with or without reflex tear fluid collected from the conjunctival sacs of human volunteers. Cytotoxicity was assessed by observation of trypan blue staining and measurement of lactate dehydrogenase release; invasion was quantified by using gentamicin survival assays. Tear fluid retarded growth of only 50% of the P. aeruginosa strains (three of five invasive strains, two of five cytotoxic strains) yet protected corneal cells against invasion by or cytotoxicity of 9 of 10 strains. The only strain resistant to the tear cytoprotective effects was susceptible to tear bacteriostatic activity. Dilution of tear fluid threefold significantly reduced cytoprotection, while bacteriostatic activity prevailed with dilutions beyond 100-fold. Sulfacetamide (1 mg/ml) with bacteriostatic activity matching that of tear fluid was less cytoprotective than tear fluid (80% protection with tear fluid, 48% with sulfacetamide). Video microscopy revealed bacterial chain formation in both tear fluid and sulfacetamide, but tear fluid also blocked bacterial swimming motility. After prolonged tear contact, bacteria regained normal growth rates, swimming motility, and cytotoxic activity, suggesting a breakdown of protective tear factors. Boiled tear fluid lost bacteriostatic activity and effects on bacterial motility but retained cytoprotective function. These results suggest that human tear fluid can protect corneal epithelial cells against P. aeruginosa virulence mechanisms in a manner not dependent upon bacteriostatic activity or effects on bacterial motility. Whether overlapping tear film components are involved in these defense functions is to be determined.
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Affiliation(s)
- Suzanne M J Fleiszig
- Morton D. Sarver Laboratory for Contact Lens and Cornea Research, School of Optometry, University of California, Berkeley, California 94720, USA.
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141
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Tollin M, Bergman P, Svenberg T, Jörnvall H, Gudmundsson GH, Agerberth B. Antimicrobial peptides in the first line defence of human colon mucosa. Peptides 2003; 24:523-30. [PMID: 12860195 DOI: 10.1016/s0196-9781(03)00114-1] [Citation(s) in RCA: 106] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Antimicrobial peptides and proteins are effector molecules in the protection of epithelial surfaces. We have evaluated the presence of antimicrobial peptides/proteins that can participate in human colonic defence against microbes. A peptide/protein extract of normal human colon mucosa was found to be active against Gram-positive bacteria, Gram-negative bacteria, and fungi. Four polypeptides with antimicrobial activity were isolated from this material and they were identified by N-terminal amino acid sequence analysis as ubiquicidin, histone H2B, eosinophil cationic protein, and phospholipase A(2) (PLA(2)). Using immunodetection and mass spectrometry, LL-37, HNP1-3, and HBD-1 were also identified. Combined, these results indicate that the colon mucosa is protected by a complex mixture of polypeptides, able to kill invading microbes and working in synergy as a barrier against bacterial invasion.
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Affiliation(s)
- Maria Tollin
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, SE-171 77 Stockholm, Sweden
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142
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Zhao H, Kinnunen PKJ. Modulation of the activity of secretory phospholipase A2 by antimicrobial peptides. Antimicrob Agents Chemother 2003; 47:965-71. [PMID: 12604528 PMCID: PMC149322 DOI: 10.1128/aac.47.3.965-971.2003] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The antimicrobial peptides magainin 2, indolicidin, and temporins B and L were found to modulate the hydrolytic activity of secretory phospholipase A(2) (sPLA(2)) from bee venom and in human lacrimal fluid. More specifically, hydrolysis of phosphatidylcholine (PC) liposomes by bee venom sPLA(2) at 10 micro M Ca(2+) was attenuated by these peptides while augmented product formation was observed in the presence of 5 mM Ca(2+). The activity of sPLA(2) towards anionic liposomes was significantly enhanced by the antimicrobial peptides at low [Ca(2+)] and was further enhanced in the presence of 5 mM Ca(2+). Similarly, with 5 mM Ca(2+) the hydrolysis of anionic liposomes was enhanced significantly by human lacrimal fluid sPLA(2), while that of PC liposomes was attenuated. These results indicate that concerted action of antimicrobial peptides and sPLA(2) could improve the efficiency of the innate response to infections. Interestingly, inclusion of a cationic gemini surfactant in the vesicles showed an essentially similar pattern on sPLA(2) activity, suggesting that the modulation of the enzyme activity by the antimicrobial peptides may involve also charge properties of the substrate surface.
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Affiliation(s)
- Hongxia Zhao
- Helsinki Biophysics & Biomembrane Group, Institute of Biomedicine, FIN-00014 University of Helsinki, Finland
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143
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Aho VV, Paavilainen V, Nevalainen TJ, Peuravuori H, Saari KM. Diurnal variation in group IIa phospholipase A2 content in tears of contact lens wearers and normal controls. Graefes Arch Clin Exp Ophthalmol 2003; 241:85-8. [PMID: 12605260 DOI: 10.1007/s00417-002-0607-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2002] [Revised: 10/28/2002] [Accepted: 11/14/2002] [Indexed: 10/22/2022] Open
Abstract
PURPOSE To study the diurnal rhythm in group IIA phospholipase A(2) (GIIAPLA(2)) content of tears and the effect of the wearing time of soft contact lenses (CL) on the content of GIIAPLA(2 )in tears. METHODS The GIIAPLA(2 )content of tears was measured by a time-resolved fluoroimmunoassay in 22 healthy controls at 8 a.m., noon, 4 p.m. and 8 p.m. and in 20 CL wearers at 4 p.m. 1-2 days before using CLs and after 4 h (at noon), 8 h (4 p.m.) and 12 h (8 p.m.) use of soft CLs. RESULTS The GIIAPLA(2 )content of tears of healthy controls was 80.6+/-47.8 micro g/ml (mean+/-SD). The GIIAPLA(2 )content was lower at 8 a.m. than at noon (p=0.006) and higher at 4 p.m. than at 8 p.m. ( P=0.003). There was no statistically significant difference in the GIIAPLA(2 )content of tears between the CL wearers without CLs (69.47+/-31.2 micro g/ml) and the normal subjects (92.3+/-48.2 micro g/ml) measured at 4 p.m. Compared with healthy controls, the GIIAPLA(2) values in subjects wearing CLs were statistically significantly lower at noon ( P=0.0001) and at 4 p.m. ( P=0.0002). CONCLUSION In normal subjects, the GIIAPLA(2) content of tears increased from 8 a.m. to noon and decreased from 4 p.m. to 8 p.m. The use of CLs for 4 h and 8 h caused a decrease in the GIIAPLA(2) content of tears. This difference was not seen at 4 p.m. the day when the CL wearers did not use CLs.
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Affiliation(s)
- Valtteri V Aho
- Department of Ophthalmology, University of Turku, 20520, Turku, Finland
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144
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Singer AG, Ghomashchi F, Le Calvez C, Bollinger J, Bezzine S, Rouault M, Sadilek M, Nguyen E, Lazdunski M, Lambeau G, Gelb MH. Interfacial kinetic and binding properties of the complete set of human and mouse groups I, II, V, X, and XII secreted phospholipases A2. J Biol Chem 2002; 277:48535-49. [PMID: 12359733 DOI: 10.1074/jbc.m205855200] [Citation(s) in RCA: 274] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Expression of the full set of human and mouse groups I, II, V, X, and XII secreted phospholipases A(2) (sPLA(2)s) in Escherichia coli and insect cells has provided pure recombinant enzymes for detailed comparative interfacial kinetic and binding studies. The set of mammalian sPLA(2)s display dramatically different sensitivity to dithiothreitol. The specific activity for the hydrolysis of vesicles of differing phospholipid composition by these enzymes varies by up to 4 orders of magnitude, and yet all enzymes display similar catalytic site specificity toward phospholipids with different polar head groups. Discrimination between sn-2 polyunsaturated versus saturated fatty acyl chains is <6-fold. These enzymes display apparent dissociation constants for activation by calcium in the 1-225 microm range, depending on the phospholipid substrate. Analysis of the inhibition by a set of 12 active site-directed, competitive inhibitors reveals a large variation in the potency among the mammalian sPLA(2)s, with Me-Indoxam being the most generally potent sPLA(2) inhibitor. A dramatic correlation exists between the ability of the sPLA(2)s to hydrolyze phosphatidylcholine-rich vesicles efficiently in vitro and the ability to release arachidonic acid when added exogenously to mammalian cells; the group V and X sPLA(2)s are uniquely efficient in this regard.
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Affiliation(s)
- Alan G Singer
- Department of Chemistry, University of Washington, Seattle 98195, USA
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145
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Leung SY, Chen X, Chu KM, Yuen ST, Mathy J, Ji J, Chan ASY, Li R, Law S, Troyanskaya OG, Tu IP, Wong J, So S, Botstein D, Brown PO. Phospholipase A2 group IIA expression in gastric adenocarcinoma is associated with prolonged survival and less frequent metastasis. Proc Natl Acad Sci U S A 2002; 99:16203-8. [PMID: 12456890 PMCID: PMC138589 DOI: 10.1073/pnas.212646299] [Citation(s) in RCA: 123] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/23/2002] [Indexed: 11/18/2022] Open
Abstract
We analyzed gene expression patterns in human gastric cancers by using cDNA microarrays representing approximately equal 30,300 genes. Expression of PLA2G2A, a gene previously implicated as a modifier of the Apc(Min/+) (multiple intestinal neoplasia 1) mutant phenotype in the mouse, was significantly correlated with patient survival. We confirmed this observation in an independent set of patient samples by using quantitative RT-PCR. Beyond its potential diagnostic and prognostic significance, this result suggests the intriguing possibility that the activity of PLA2G2A may suppress progression or metastasis of human gastric cancer.
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Affiliation(s)
- Suet Y Leung
- Departments of Pathology and Surgery, University of Hong Kong, Hong Kong, China
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146
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Koprivnjak T, Peschel A, Gelb MH, Liang NS, Weiss JP. Role of charge properties of bacterial envelope in bactericidal action of human group IIA phospholipase A2 against Staphylococcus aureus. J Biol Chem 2002; 277:47636-44. [PMID: 12359734 DOI: 10.1074/jbc.m205104200] [Citation(s) in RCA: 97] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mammalian Group IIA phospholipases A(2) (PLA(2)) potently kill Staphylococcus aureus. Highly cationic properties of these PLA(2) are important for Ca(2+)-independent binding and cell wall penetration, prerequisites for Ca(2+)-dependent degradation of membrane phospholipids and bacterial killing. To further delineate charge properties of the bacterial envelope important in Group IIA PLA(2) action against S. aureus, we examined the effects of mutations that prevent specific modifications of cell wall (dltA) and cell membrane (mprF) polyanions. In comparison to the parent strain, isogenic dltA(-) bacteria are approximately 30-100x more sensitive to PLA(2), whereas mprF(-) bacteria are <3-fold more sensitive. Differences in PLA(2) sensitivity of intact bacteria reflect differences in cell wall, not cell membrane, properties since protoplasts from all three strains are equally sensitive to PLA(2). A diminished positive charge in PLA(2) reduces PLA(2) binding and antibacterial activity. In contrast, diminished cell wall negative charge by substitution of (lipo)teichoic acids with d-alanine reduces antibacterial activity of bound PLA(2), but not initial PLA(2) binding. Therefore, the potent antistaphylococcal activity of Group IIA PLA(2) depends on cationic properties of the enzyme that promote binding to the cell wall, and polyanionic properties of cell wall (lipo)teichoic acids that promote attack of membrane phospholipids by bound PLA(2).
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Affiliation(s)
- Tomaz Koprivnjak
- Department of Microbiology, University of Iowa, Iowa City Veterans Affairs Medical Center, Iowa City, Iowa 52246, USA
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147
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Bezzine S, Bollinger JG, Singer AG, Veatch SL, Keller SL, Gelb MH. On the Binding Preference of Human Groups IIA and X Phospholipases A2 for Membranes with Anionic Phospholipids. J Biol Chem 2002; 277:48523-34. [PMID: 12244093 DOI: 10.1074/jbc.m203137200] [Citation(s) in RCA: 109] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mammals contain 9-10 secreted phospholipases A(2) (sPLA(2)s) that display widely different affinities for membranes, depending on the phospholipid composition. The much higher enzymatic activity of human group X sPLA(2) (hGX) compared with human group IIA sPLA(2) (hGIIA) on phosphatidylcholine (PC)-rich vesicles is due in large part to the higher affinity of the former enzyme for such vesicles; this result also holds when vesicles contain cholesterol and sphingomyelin. The inclusion of anionic phosphatidylserine in PC vesicles dramatically enhances interfacial binding and catalysis of hGIIA but not of hGX. This is the result of the large number of lysine and arginine residues scattered over the entire surface of hGIIA, which cause the enzyme to form a supramolecular aggregate with multiple vesicles. Thus, high affinity binding of hGIIA to anionic vesicles is a complex process and cannot be attributed to a few basic residues on its interfacial binding surface, as is also evident from mutagenesis studies. The main reason hGIIA binds poorly to PC-rich vesicles is that it lacks a tryptophan residue on its interfacial binding surface, a residue that contributes to the high affinity binding of hGX to PC-rich vesicles. Results show that the lag in the onset of hydrolysis of PC vesicles by hGIIA is due in part to the poor affinity of this enzyme for these vesicles. Binding affinity of hGIIA, hGX, and their mutants to PC-rich vesicles is well correlated to the ability of these enzymes to act on the PC-rich outer plasma membrane of mammalian cells.
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Affiliation(s)
- Sofiane Bezzine
- Department of Chemistry, University of Washington, Seattle 98195, USA.
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148
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Paulsen F, Pufe T, Conradi L, Varoga D, Tsokos M, Papendieck J, Petersen W. Antimicrobial peptides are expressed and produced in healthy and inflamed human synovial membranes. J Pathol 2002; 198:369-77. [PMID: 12375270 DOI: 10.1002/path.1224] [Citation(s) in RCA: 100] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The objective of this study was to determine the expression and production of antimicrobial peptides by healthy and inflamed human synovial membranes. Deposition of the antimicrobial peptides lysozyme, lactoferrin, secretory phospholipase A(2) (sPA(2)), matrilysin (MMP7), human neutrophil alpha-defensins 1-3 (HNP 1-3), human beta-defensin 1 (HBD-1), and human beta-defensin 2 (HBD-2) was determined by immunohistochemistry. Expression of mRNA for the antimicrobial peptides bactericidal permeability-increasing protein (BPI), heparin binding protein (CAP37), human cationic antimicrobial protein (LL37), human alpha-defensin 5 (HD5), human alpha-defensin 6 (HD6), HBD-1, HBD-2, and human beta-defensin 3 (HBD-3) was analysed by reverse transcription polymerase chain reaction (RT-PCR). RT-PCR revealed CAP37 and HBD-1 mRNA in samples of healthy synovial membrane. Additionally, HBD-3 and/or LL37 mRNA was detected in synovial membrane samples from patients with pyogenic arthritis (PA), osteoarthritis (OA) or rheumatoid arthritis (RA). BPI, HD5, HD6, and HBD-2 mRNAs were absent from all samples investigated. Immunohistochemistry identified lysozyme, lactoferrin, sPA(2), and MMP7 in type A synoviocytes of all samples. HBD-1 was only present in type B synoviocytes of some of the samples. Immunoreactive HBD-2 peptide was only visible in some inflamed samples. HNP1-3 was detected in both healthy and inflamed synovial membranes. The data suggest that human synovial membranes produce a broad spectrum of antimicrobial peptides. Under inflammatory conditions, the expression pattern changes, with induction of HBD-3 in PA (LL37 in RA; HBD-3 and LL37 in OA) as well as down-regulation of HBD-1. HBD-3 holds therapeutic potential in PA as it has a broad spectrum of antimicrobial activity and accelerates epithelial healing. However, caution is appropriate since defensins also promote fibrin formation and cell proliferation - key elements in joint infection. Clarification of the role of antimicrobial peptides in OA and RA will require further investigation.
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Affiliation(s)
- Friedrich Paulsen
- Institute of Anatomy, Christian Albrecht University of Kiel, Germany.
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149
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Canaan S, Nielsen R, Ghomashchi F, Robinson BH, Gelb MH. Unusual mode of binding of human group IIA secreted phospholipase A2 to anionic interfaces as studied by continuous wave and time domain electron paramagnetic resonance spectroscopy. J Biol Chem 2002; 277:30984-90. [PMID: 12039961 DOI: 10.1074/jbc.m203649200] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Human group IIA phospholipase A(2) (hGIIA) is secreted from a number of cells during inflammation and is known to interact strongly with anionic membranes and to exhibit potent Gram-positive bactericidal activity. This protein contains 23 cationic residues, which are scattered over its entire surface, resulting in a high pI of 9.39. To understand the molecular basis for the selective binding of hGIIA to anionic membranes, 14 single-site, spin-labeled hGIIA proteins were analyzed in the presence and absence of vesicles of anionic phospholipid by time domain and continuous wave electron paramagnetic resonance (EPR) spin relaxant techniques. Surprisingly, for hGIIA bound to anionic vesicles, all of the spin labels were highly protected from water-soluble spin relaxants. Together with light scattering studies, these EPR results suggest the formation of a supramolecular aggregate involving clusters of hGIIA molecules bridging together multiple vesicles. This anomalous mode of binding of hGIIA to anionic phospholipid explains previous data in which charge reversal mutation of a few cationic residues on multiple faces of hGIIA leads to a comparable and modest reduction in affinity of the protein for anionic vesicles. In the presence of mixed micelles composed of 10% anionic phospholipids in Triton X-100 a monodisperse protein-lipid complex is formed. Under these conditions, the EPR methods were used to map the surface of hGIIA that constitutes the interfacial binding site (IBS). The IBS of hGIIA consists of the highly hydrophobic surface that surrounds the opening to the active site slot.
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Affiliation(s)
- Stéphane Canaan
- Departments of Chemistry and Biochemistry, University of Washington, Seattle, WA 98195, USA
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150
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Abstract
Phospholipase A2 (PLA2) catalyzes the hydrolysis of the sn-2 position of membrane glycerophospholipids to liberate arachidonic acid (AA), a precursor of eicosanoids including prostaglandins and leukotrienes. The same reaction also produces lysophosholipids, which represent another class of lipid mediators. So far, at least 19 enzymes that possess PLA2 activity have been identified and cloned in mammals. The secretory PLA2 (sPLA2) family, in which 10 isozymes have been identified, consists of low-molecular weight, Ca2+-requiring secretory enzymes that have been implicated in a number of biological processes, such as modification of eicosanoid generation, inflammation, and host defense. The cytosolic PLA2 (cPLA2) family consists of three enzymes, among which cPLA2alpha has been paid much attention by researchers as an essential component of the initiation of AA metabolism. The activation of cPLA2alpha is tightly regulated by Ca2+ and phosphorylation. The Ca2+-independent PLA2 (iPLA2) family contains two enzymes and may play a major role in phospholipid remodeling. The platelet-activating factor (PAF) acetylhydrolase (PAF-AH) family contains four enzymes that exhibit unique substrate specificity toward PAF and/or oxidized phospholipids. Degradation of these bioactive phospholipids by PAF-AHs may lead to the termination of inflammatory reaction and atherosclerosis.
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Affiliation(s)
- Ichiro Kudo
- Department of Health Chemistry, School of Pharmaceutical Sciences, Showa University, Tokyo, Japan.
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