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Hamu-Tanoue A, Takagi K, Taketomi Y, Miki Y, Nishito Y, Kano K, Aoki J, Matsuyama T, Kondo K, Dotake Y, Matsuyama H, Machida K, Murakami M, Inoue H. Group III secreted phospholipase A 2 -driven lysophospholipid pathway protects against allergic asthma. FASEB J 2024; 38:e23428. [PMID: 38236184 DOI: 10.1096/fj.202301976r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2023] [Revised: 12/21/2023] [Accepted: 01/03/2024] [Indexed: 01/19/2024]
Abstract
Asthma is a chronic inflammatory disease of the airways characterized by recurrent episodes of airway obstruction, hyperresponsiveness, remodeling, and eosinophilia. Phospholipase A2 s (PLA2 s), which release fatty acids and lysophospholipids from membrane phospholipids, have been implicated in exacerbating asthma by generating pro-asthmatic lipid mediators, but an understanding of the association between individual PLA2 subtypes and asthma is still incomplete. Here, we show that group III-secreted PLA2 (sPLA2 -III) plays an ameliorating, rather than aggravating, role in asthma pathology. In both mouse and human lungs, sPLA2 -III was expressed in bronchial epithelial cells and decreased during the asthmatic response. In an ovalbumin (OVA)-induced asthma model, Pla2g3-/- mice exhibited enhanced airway hyperresponsiveness, eosinophilia, OVA-specific IgE production, and type 2 cytokine expression as compared to Pla2g3+/+ mice. Lipidomics analysis showed that the pulmonary levels of several lysophospholipids, including lysophosphatidylcholine, lysophosphatidylethanolamine, and lysophosphatidic acid (LPA), were decreased in OVA-challenged Pla2g3-/- mice relative to Pla2g3+/+ mice. LPA receptor 2 (LPA2 ) agonists suppressed thymic stromal lymphopoietin (TSLP) expression in bronchial epithelial cells and reversed airway hyperresponsiveness and eosinophilia in Pla2g3-/- mice, suggesting that sPLA2 -III negatively regulates allergen-induced asthma at least by producing LPA. Thus, the activation of the sPLA2 -III-LPA pathway may be a new therapeutic target for allergic asthma.
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Affiliation(s)
- Asako Hamu-Tanoue
- Department of Pulmonary Medicine, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - Koichi Takagi
- Department of Pulmonary Medicine, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - Yoshitaka Taketomi
- Laboratory of Microenvironmental and Metabolic Health Science, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
- Center for Basic Technology Research, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan
| | - Yoshimi Miki
- Laboratory of Microenvironmental and Metabolic Health Science, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Yasumasa Nishito
- Center for Basic Technology Research, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan
| | - Kuniyuki Kano
- Department of Health Chemistry, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan
| | - Junken Aoki
- Department of Health Chemistry, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan
| | - Takahiro Matsuyama
- Department of Pulmonary Medicine, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - Kiyotaka Kondo
- Department of Pulmonary Medicine, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - Yoichi Dotake
- Department of Pulmonary Medicine, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - Hiromi Matsuyama
- Department of Pulmonary Medicine, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - Kentaro Machida
- Department of Pulmonary Medicine, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - Makoto Murakami
- Laboratory of Microenvironmental and Metabolic Health Science, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
- AMED-CREST, Japan Agency for Medical Research and Development, Tokyo, Japan
| | - Hiromasa Inoue
- Department of Pulmonary Medicine, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
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2
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Vieira BM, de São José VS, Niemeyer Filho PS, Moura-Neto V. Eosinophils induces glioblastoma cell suppression and apoptosis - Roles of GM-CSF and cysteinyl-leukotrienes. Int Immunopharmacol 2023; 123:110729. [PMID: 37536182 DOI: 10.1016/j.intimp.2023.110729] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2023] [Revised: 07/10/2023] [Accepted: 07/27/2023] [Indexed: 08/05/2023]
Abstract
BACKGROUND Glioblastoma is the most common and lethal primary brain tumor in adults. Despite the available cancer treatments, the recurrence of the tumor is high, and the survival rate is low. New approaches to antitumor therapies are needed. Eosinophils are prominent in allergic diseases and accumulate in several human brain tumors. Recently, the antitumor role of eosinophils has been targeted as eosinophils release several cytotoxic factors that induce cell impairment and death. OBJECTIVE Here we aim to evaluate the interaction of the eosinophil and glioblastoma cells, the mechanism involved in the potential killing of the glioblastoma cells by the eosinophils, and how allergy/asthma could confer a better glioblastoma prognosis. METHODS Eosinophils and serum from asthmatic and non-asthmatic donors were cultivated with different glioblastoma cell lines. RESULTS Glioblastoma cells recruit eosinophils via GM-CSF signaling, activating and increasing eosinophil survivability and function on a GM-CSF-dependent manner. Eosinophils reduce glioblastoma cells metabolism, proliferation, and migration, via Fas/FasL. Cysteinyl-leukotrienes are accounted for the asthmatic serum enhancement of the glioblastoma cell migration and proliferation. Cysteinyl-leukotrienes enhance glioblastoma cell proliferation and migration, albeit activate eosinophils that suppress glioblastoma cells. CONCLUSION Eosinophils have the potential to be key cells on glioblastoma therapeutics, as allergy and eosinophilia are correlated with a better glioblastoma prognosis. Eosinophils are elicited and attach to glioblastoma cells, where, by its cytotoxic function, via Fas/FasL, hind glioblastoma cell metabolism, proliferation, migration, and induce cell death.
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Affiliation(s)
- Bruno Marques Vieira
- Laboratório de Biomedicina do Cérebro, Instituto Estadual do Cérebro Paulo Niemeyer (IECPN), Rio de Janeiro, Brazil.
| | - Vitória Santório de São José
- Laboratório de Biomedicina do Cérebro, Instituto Estadual do Cérebro Paulo Niemeyer (IECPN), Rio de Janeiro, Brazil; Laboratório de Avaliação e Síntese de Substâncias Bioativas (LASSBio®), Instituto Nacional de Ciência e Tecnologia de Fármacos e Medicamentos (INCT-INOFAR), Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Paulo Soares Niemeyer Filho
- Laboratório de Biomedicina do Cérebro, Instituto Estadual do Cérebro Paulo Niemeyer (IECPN), Rio de Janeiro, Brazil
| | - Vivaldo Moura-Neto
- Laboratório de Biomedicina do Cérebro, Instituto Estadual do Cérebro Paulo Niemeyer (IECPN), Rio de Janeiro, Brazil
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3
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Murakami M, Sato H, Taketomi Y. Modulation of immunity by the secreted phospholipase A 2 family. Immunol Rev 2023; 317:42-70. [PMID: 37035998 DOI: 10.1111/imr.13205] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Revised: 03/23/2023] [Accepted: 03/28/2023] [Indexed: 04/11/2023]
Abstract
Among the phospholipase A2 (PLA2 ) superfamily, which typically catalyzes the sn-2 hydrolysis of phospholipids to yield fatty acids and lysophospholipids, the secreted PLA2 (sPLA2 ) family contains 11 isoforms in mammals. Individual sPLA2 s have unique enzymatic specificity toward fatty acids and polar heads of phospholipid substrates and display distinct tissue/cellular distributions, suggesting their distinct physiological functions. Recent studies using knockout and/or transgenic mice for a full set of sPLA2 s have revealed their roles in modulation of immunity and related disorders. Application of mass spectrometric lipidomics to these mice has enabled to identify target substrates and products of individual sPLA2 s in given tissue microenvironments. sPLA2 s hydrolyze not only phospholipids in the plasma membrane of activated, damaged or dying mammalian cells, but also extracellular phospholipids such as those in extracellular vesicles, microbe membranes, lipoproteins, surfactants, and dietary phospholipids, thereby exacerbating or ameliorating various diseases. The actions of sPLA2 s are dependent on, or independent of, the generation of fatty acid- or lysophospholipid-derived lipid mediators according to the pathophysiological contexts. In this review, we make an overview of our current understanding of the roles of individual sPLA2 s in various immune responses and associated diseases.
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Affiliation(s)
- Makoto Murakami
- Laboratory of Microenvironmental and Metabolic Health Science, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
- AMED-CREST, Japan Agency for Medical Research and Development, Tokyo, Japan
| | - Hiroyasu Sato
- Laboratory of Microenvironmental and Metabolic Health Science, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Yoshitaka Taketomi
- Laboratory of Microenvironmental and Metabolic Health Science, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
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4
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Jaiswal A, Rehman R, Dutta J, Singh S, Ray A, Shridhar M, Jaisankar J, Bhatt M, Khandelwal D, Sahoo B, Ram A, Mabalirajan U. Cellular Distribution of Secreted Phospholipase A2 in Lungs of IPF Patients and Its Inhibition in Bleomycin-Induced Pulmonary Fibrosis in Mice. Cells 2023; 12:cells12071044. [PMID: 37048117 PMCID: PMC10092981 DOI: 10.3390/cells12071044] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Revised: 01/13/2023] [Accepted: 01/29/2023] [Indexed: 04/03/2023] Open
Abstract
Idiopathic pulmonary fibrosis (IPF) is a chronic lung disease with a very poor prognosis as it has a 2.5 to 5 years mean survival after proper diagnosis. Even nintedanib and pirfenidone cannot halt the progression, though they slow the progression of IPF. Hence, there is a need to understand the novel pathophysiology. Phospholipase A2 (PLA2) could be the ideal candidate to study in IPF, as they have a role in both inflammation and fibrosis. In the present study, we have shown the expression profile of various secretory Phospholipase A2 (PLA2) isoforms by analyzing publicly available transcriptome data of single cells from the lungs of healthy individuals and IPF patients. Among 11 members of sPLA2, PLA2G2A is found to be increased in the fibroblasts and mesothelial cells while PLA2G5 is found to be increased in the fibroblasts of IPF patients. We identified a subset of fibroblasts expressing high PLA2G2A with moderate expression of PLA2G5 and which are specific to IPF only; we named it as PLA2G2A+ IPF fibroblast. Pathway analysis revealed that these PLA2G2A+ IPF fibroblast have upregulation of both inflammatory and fibrosis-related pathways like the TGF-β signaling pathway, IL-17 signaling, the arachidonic acid metabolism pathway and ECM-receptor interaction. In addition to this, we found elevated levels of sPLA2-IIA in plasma samples of IPF patients in our cohort. PLA2G3, PLA2G10 and PLA2G12B are found in to be increased in certain epithelial cells of IPF patients. Thus, these findings indicate that these five isoforms have a disease-dominant role along with innate immune roles as these isoforms are found predominantly in structural cells of IPF patients. Further, we have targeted sPLA2 in mice model of bleomycin-induced lung fibrosis by pBPB, a known sPLA2 inhibitor. pBPB treatment attenuated lung fibrosis induced by bleomycin along with a reduction in TGF-β and deposition of extracellular matrix in lung. Thus, these findings indicate that these sPLA2 isoforms especially PLA2G2A may serve as a therapeutic target in lung fibrosis.
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5
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Petan T, Manček-Keber M. Half is enough: Oxidized lysophospholipids as novel bioactive molecules. Free Radic Biol Med 2022; 188:351-362. [PMID: 35779690 DOI: 10.1016/j.freeradbiomed.2022.06.228] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Revised: 06/01/2022] [Accepted: 06/13/2022] [Indexed: 10/17/2022]
Abstract
Studies in the last decade have established the roles of oxidized phospholipids as modulators of various cellular processes, from inflammation and immunity to cell death. Oxidized lysophospholipids, formed through the activity of phospholipases and oxidative enzymes and lacking an acyl chain in comparison with parent phospholipids, are now emerging as novel bioactive lipid mediators. Their detection and structural characterization have been limited in the past due to low amounts and the complexity of their biosynthetic and removal pathways, but recent studies have unequivocally demonstrated their formation under inflammatory conditions. The involvement of oxidized lysophospholipids in immune regulation classifies them as damage-associated molecular patterns (DAMPs), which can promote sterile inflammation and contribute to autoimmune and chronic diseases as well as aging-related diseases. Their signaling pathways are just beginning to be revealed. As the first publications indicate that oxidized lysophospholipids use the same receptors as pathogen-associated molecular patterns (PAMPs), it is likely that the inhibition of signaling pathways activated by oxidized lysophospholipids would affect innate immunity per se. On the other hand, inhibition or modulation of their enzymatic formation, which would not interfere with the response to pathogens, might be beneficial and is potentially a promising new field of research.
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Affiliation(s)
- Toni Petan
- Department of Molecular and Biomedical Sciences, Jožef Stefan Institute, 1000, Ljubljana, Slovenia.
| | - Mateja Manček-Keber
- Department of Synthetic Biology and Immunology, National Institute of Chemistry, 1000, Ljubljana, Slovenia.
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Kartha S, Ghimire P, Winkelstein BA. Inhibiting spinal secretory phospholipase A 2 after painful nerve root injury attenuates established pain and spinal neuronal hyperexcitability by altering spinal glutamatergic signaling. Mol Pain 2021; 17:17448069211066221. [PMID: 34919471 PMCID: PMC8721705 DOI: 10.1177/17448069211066221] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Neuropathic injury is accompanied by chronic inflammation contributing to the onset and maintenance of pain after an initial insult. In addition to their roles in promoting immune cell activation, inflammatory mediators like secretory phospholipase A2 (sPLA2) modulate nociceptive and excitatory neuronal signaling during the initiation of pain through hydrolytic activity. Despite having a known role in glial activation and cytokine release, it is unknown if sPLA2 contributes to the maintenance of painful neuropathy and spinal hyperexcitability later after neural injury. Using a well-established model of painful nerve root compression, this study investigated if inhibiting spinal sPLA2 7 days after painful injury modulates the behavioral sensitivity and/or spinal dorsal horn excitability that is typically evident. The effects of sPLA2 inhibition on altered spinal glutamatergic signaling was also probed by measuring spinal intracellular glutamate levels and spinal glutamate transporter (GLAST and GLT1) and receptor (mGluR5, GluR1, and NR1) expression. Spinal sPLA2 inhibition at day 7 abolishes behavioral sensitivity, reduces both evoked and spontaneous neuronal firing in the spinal cord, and restores the distribution of neuronal phenotypes to those of control conditions. Inhibiting spinal sPLA2 also increases intracellular glutamate concentrations and restores spinal expression of GLAST, GLT1, mGluR5, and GluR1 to uninjured expression with no effect on NR1. These findings establish a role for spinal sPLA2 in maintaining pain and central sensitization after neural injury and suggest this may be via exacerbating glutamate excitotoxicity in the spinal cord.
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Affiliation(s)
- Sonia Kartha
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, USA
| | - Prabesh Ghimire
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, USA
| | - Beth A Winkelstein
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, USA.,Department of Neurosurgery, University of Pennsylvania, Hospital of the University of Pennsylvania, Philadelphia, PA, USA
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7
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Knuplez E, Sturm EM, Marsche G. Emerging Role of Phospholipase-Derived Cleavage Products in Regulating Eosinophil Activity: Focus on Lysophospholipids, Polyunsaturated Fatty Acids and Eicosanoids. Int J Mol Sci 2021; 22:4356. [PMID: 33919453 PMCID: PMC8122506 DOI: 10.3390/ijms22094356] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 04/16/2021] [Accepted: 04/19/2021] [Indexed: 12/19/2022] Open
Abstract
Eosinophils are important effector cells involved in allergic inflammation. When stimulated, eosinophils release a variety of mediators initiating, propagating, and maintaining local inflammation. Both, the activity and concentration of secreted and cytosolic phospholipases (PLAs) are increased in allergic inflammation, promoting the cleavage of phospholipids and thus the production of reactive lipid mediators. Eosinophils express high levels of secreted phospholipase A2 compared to other leukocytes, indicating their direct involvement in the production of lipid mediators during allergic inflammation. On the other side, eosinophils have also been recognized as crucial mediators with regulatory and homeostatic roles in local immunity and repair. Thus, targeting the complex network of lipid mediators offer a unique opportunity to target the over-activation and 'pro-inflammatory' phenotype of eosinophils without compromising the survival and functions of tissue-resident and homeostatic eosinophils. Here we provide a comprehensive overview of the critical role of phospholipase-derived lipid mediators in modulating eosinophil activity in health and disease. We focus on lysophospholipids, polyunsaturated fatty acids, and eicosanoids with exciting new perspectives for future drug development.
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Affiliation(s)
| | | | - Gunther Marsche
- Otto Loewi Research Center, Division of Pharmacology, Medical University of Graz, 8010 Graz, Austria; (E.K.); (E.M.S.)
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8
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Ogden HL, Lai Y, Nolin JD, An D, Frevert CW, Gelb MH, Altemeier WA, Hallstrand TS. Secreted Phospholipase A 2 Group X Acts as an Adjuvant for Type 2 Inflammation, Leading to an Allergen-Specific Immune Response in the Lung. THE JOURNAL OF IMMUNOLOGY 2020; 204:3097-3107. [PMID: 32341057 DOI: 10.4049/jimmunol.2000102] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Accepted: 04/05/2020] [Indexed: 11/19/2022]
Abstract
Secreted phospholipase A2 (sPLA2) enzymes release free fatty acids, including arachidonic acid, and generate lysophospholipids from phospholipids, including membrane phospholipids from cells and bacteria and surfactant phospholipids. We have shown that an endogenous enzyme sPLA2 group X (sPLA2-X) is elevated in the airways of asthmatics and that mice lacking the sPLA2-X gene (Pla2g10) display attenuated airway hyperresponsiveness, innate and adaptive immune responses, and type 2 cytokine production in a model of airway sensitization and challenge using a complete allergen that induces endogenous adjuvant activity. This complete allergen also induces the expression of sPLA2-X/Pla2g10 In the periphery, an sPLA2 found in bee venom (bee venom PLA2) administered with the incomplete Ag OVA leads to an Ag-specific immune response. In this study, we demonstrate that both bee venom PLA2 and murine sPLA2-X have adjuvant activity, leading to a type 2 immune response in the lung with features of airway hyperresponsiveness and Ag-specific type 2 airway inflammation following peripheral sensitization and subsequent airway challenge with OVA. Further, the adjuvant effects of sPLA2-X that result in the type 2-biased OVA-specific adaptive immune response in the lung were dependent upon the catalytic activity of the enzyme, as a catalytically inactive mutant form of sPLA2-X does not elicit the adaptive component of the immune response, although other components of the immune response were induced by the inactive enzyme, suggesting receptor-mediated effects. Our results demonstrate that exogenous and endogenous sPLA2s play an important role in peripheral sensitization, resulting in airway responses to inhaled Ags.
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Affiliation(s)
- Herbert Luke Ogden
- Division of Pulmonary, Critical Care and Sleep, Department of Medicine, University of Washington, Seattle, WA 98109
| | - Ying Lai
- Division of Pulmonary, Critical Care and Sleep, Department of Medicine, University of Washington, Seattle, WA 98109
| | - James D Nolin
- Division of Pulmonary, Critical Care and Sleep, Department of Medicine, University of Washington, Seattle, WA 98109
| | - Dowon An
- Division of Pulmonary, Critical Care and Sleep, Department of Medicine, University of Washington, Seattle, WA 98109
| | - Charles W Frevert
- Division of Pulmonary, Critical Care and Sleep, Department of Medicine, University of Washington, Seattle, WA 98109.,Department of Comparative Medicine, University of Washington, Seattle, WA 98109
| | - Michael H Gelb
- Department of Chemistry, University of Washington, Seattle, WA 98195; and.,Department of Biochemistry, University of Washington, Seattle, WA 98195
| | - William A Altemeier
- Division of Pulmonary, Critical Care and Sleep, Department of Medicine, University of Washington, Seattle, WA 98109
| | - Teal S Hallstrand
- Division of Pulmonary, Critical Care and Sleep, Department of Medicine, University of Washington, Seattle, WA 98109;
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9
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Knuplez E, Curcic S, Theiler A, Bärnthaler T, Trakaki A, Trieb M, Holzer M, Heinemann A, Zimmermann R, Sturm EM, Marsche G. Lysophosphatidylcholines inhibit human eosinophil activation and suppress eosinophil migration in vivo. Biochim Biophys Acta Mol Cell Biol Lipids 2020; 1865:158686. [PMID: 32171907 DOI: 10.1016/j.bbalip.2020.158686] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Revised: 03/04/2020] [Accepted: 03/09/2020] [Indexed: 02/08/2023]
Abstract
Eosinophils are important multifaceted effector cells involved in allergic inflammation. Following allergen challenge, eosinophils and other immune cells release secreted phospholipases, generating lysophosphatidylcholines (LPCs). LPCs are potent lipid mediators, and serum levels of LPCs associate with asthma severity, suggesting a regulatory activity of LPCs in asthma development. As of yet, the direct effects of LPCs on eosinophils remain unclear. In the present study, we tested the effects of the major LPC species (16:0, 18:0 and 18:1) on eosinophils isolated from healthy human donors. Addition of saturated LPCs in the presence of albumin rapidly disrupted cholesterol-rich nanodomains on eosinophil cell membranes and suppressed multiple eosinophil effector responses, such as CD11b upregulation, degranulation, chemotaxis, and downstream signaling. Furthermore, we demonstrate in a mouse model of allergic cell recruitment, that LPC treatment markedly reduces immune cell infiltration into the lungs. Our observations suggest a strong modulatory activity of LPCs in the regulation of eosinophilic inflammation in vitro and in vivo.
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Affiliation(s)
- Eva Knuplez
- Division of Pharmacology, Otto Loewi Research Center, Medical University of Graz, Universitätsplatz 4, 8010 Graz, Austria
| | - Sanja Curcic
- Division of Biophysics, Gottfried-Schatz-Research-Center, Medical University of Graz, Neue Stiftingtalstrasse 6/D04, 8010 Graz, Austria
| | - Anna Theiler
- Division of Pharmacology, Otto Loewi Research Center, Medical University of Graz, Universitätsplatz 4, 8010 Graz, Austria
| | - Thomas Bärnthaler
- Division of Pharmacology, Otto Loewi Research Center, Medical University of Graz, Universitätsplatz 4, 8010 Graz, Austria
| | - Athina Trakaki
- Division of Pharmacology, Otto Loewi Research Center, Medical University of Graz, Universitätsplatz 4, 8010 Graz, Austria
| | - Markus Trieb
- Division of Pharmacology, Otto Loewi Research Center, Medical University of Graz, Universitätsplatz 4, 8010 Graz, Austria; BioTechMed-Graz, Graz, Austria
| | - Michael Holzer
- Division of Pharmacology, Otto Loewi Research Center, Medical University of Graz, Universitätsplatz 4, 8010 Graz, Austria; BioTechMed-Graz, Graz, Austria
| | - Akos Heinemann
- Division of Pharmacology, Otto Loewi Research Center, Medical University of Graz, Universitätsplatz 4, 8010 Graz, Austria; BioTechMed-Graz, Graz, Austria
| | - Robert Zimmermann
- BioTechMed-Graz, Graz, Austria; Institute of Molecular Biosciences, University of Graz, Graz, Austria
| | - Eva M Sturm
- Division of Pharmacology, Otto Loewi Research Center, Medical University of Graz, Universitätsplatz 4, 8010 Graz, Austria
| | - Gunther Marsche
- Division of Pharmacology, Otto Loewi Research Center, Medical University of Graz, Universitätsplatz 4, 8010 Graz, Austria; BioTechMed-Graz, Graz, Austria.
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10
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Cysteinyl leukotriene metabolism of human eosinophils in allergic disease. Allergol Int 2020; 69:28-34. [PMID: 31248811 DOI: 10.1016/j.alit.2019.06.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Revised: 05/09/2019] [Accepted: 05/23/2019] [Indexed: 01/14/2023] Open
Abstract
Eosinophils are multifaceted immune cells with diverse functions that enhance allergic inflammation. Cysteinyl leukotrienes (cys-LTs), mainly synthesized in eosinophils, are a class of inflammatory lipid mediators produced via multiple enzymatic reactions from arachidonic acid. Multiple clinical studies have reported dysregulated fatty acid metabolism in severe asthma and aspirin-exacerbated respiratory diseases. Therefore, understanding the mechanism responsible for this metabolic abnormality has attracted a lot of attention. In eosinophils, various stimuli (including cytokines, chemokines, and pathogen-derived factors) prime and/or induce leukotriene generation and secretion. Cell-cell interactions with component cells (endothelial cells, epithelial cells, fibroblasts) also enhance this machinery to augment allergic responses. Nasal polyp-derived eosinophils from patients with eosinophilic rhinosinusitis present a characteristic fatty acid metabolism with selectively higher production of leukotriene D4. Interestingly, type 2 cytokines and microbiome components might be responsible for this metabolic change with altered enzyme expression. Here, we review the regulation of fatty acid metabolism, especially cys-LT metabolism, in human eosinophils toward allergic inflammatory status.
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11
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Kippelen P, Anderson SD, Hallstrand TS. Mechanisms and Biomarkers of Exercise-Induced Bronchoconstriction. Immunol Allergy Clin North Am 2019; 38:165-182. [PMID: 29631728 DOI: 10.1016/j.iac.2018.01.008] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Exercise is a common trigger of bronchoconstriction. In recent years, there has been increased understanding of the pathophysiology of exercise-induced bronchoconstriction. Although evaporative water loss and thermal changes have been recognized stimuli for exercise-induced bronchoconstriction, accumulating evidence points toward a pivotal role for the airway epithelium in orchestrating the inflammatory response linked to exercise-induced bronchoconstriction. Overproduction of inflammatory mediators, underproduction of protective lipid mediators, and infiltration of the airways with eosinophils and mast cells are all established contributors to exercise-induced bronchoconstriction. Sensory nerve activation and release of neuropeptides maybe important in exercise-induced bronchoconstriction, but further research is warranted.
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Affiliation(s)
- Pascale Kippelen
- Department of Life Sciences, Division of Sport, Health and Exercise Sciences, Centre for Human Performance, Exercise and Rehabilitation, Brunel University London, Kingston Lane, Uxbridge UB8 3PH, UK
| | - Sandra D Anderson
- Central Clinical School, Sydney Medical School, University of Sydney, Parramatta Road, Sydney New South Wales 2006, Australia.
| | - Teal S Hallstrand
- Department of Medicine, Division of Pulmonary, Critical Care and Sleep Medicine, Center for Lung Biology, University of Washington, Box 358052, 850 Republican Street, Seattle, WA 98109-4714, USA
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12
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Nolin JD, Murphy RC, Gelb MH, Altemeier WA, Henderson WR, Hallstrand TS. Function of secreted phospholipase A 2 group-X in asthma and allergic disease. Biochim Biophys Acta Mol Cell Biol Lipids 2018; 1864:827-837. [PMID: 30529275 DOI: 10.1016/j.bbalip.2018.11.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Revised: 11/28/2018] [Accepted: 11/30/2018] [Indexed: 12/11/2022]
Abstract
Elevated secreted phospholipase A2 (sPLA2) activity in the airways has been implicated in the pathogenesis of asthma and allergic disease for some time. The identity and function of these enzymes in asthma is becoming clear from work in our lab and others. We focused on sPLA2 group X (sPLA2-X) after identifying increased levels of this enzyme in asthma, and that it is responsible for a large portion of sPLA2 activity in the airways and that the levels are strongly associated with features of airway hyperresponsiveness (AHR). In this review, we discuss studies that implicated sPLA2-X in human asthma, and murine models that demonstrate a critical role of this enzyme as a regulator of type-2 inflammation, AHR and production of eicosanoids. We discuss the mechanism by which sPLA2-X acts to regulate eicosanoids in leukocytes, as well as effects that are mediated through the generation of lysophospholipids and through receptor-mediated functions. This article is part of a Special Issue entitled Novel functions of phospholipase A2 Guest Editors: Makoto Murakami and Gerard Lambeau.
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Affiliation(s)
- James D Nolin
- Department of Medicine, Division of Pulmonary, Critical Care and Sleep, University of Washington, Seattle, WA, United States of America
| | - Ryan C Murphy
- Department of Medicine, Division of Pulmonary, Critical Care and Sleep, University of Washington, Seattle, WA, United States of America
| | - Michael H Gelb
- Department of Chemistry, University of Washington, Seattle, WA, United States of America; Department of Biochemistry, University of Washington, Seattle, WA, United States of America
| | - William A Altemeier
- Department of Medicine, Division of Pulmonary, Critical Care and Sleep, University of Washington, Seattle, WA, United States of America
| | - William R Henderson
- Division of Allergy and Infectious DIseases, University of Washington, Seattle, WA, United States of America
| | - Teal S Hallstrand
- Department of Medicine, Division of Pulmonary, Critical Care and Sleep, University of Washington, Seattle, WA, United States of America.
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Samuchiwal SK, Balestrieri B. Harmful and protective roles of group V phospholipase A 2: Current perspectives and future directions. Biochim Biophys Acta Mol Cell Biol Lipids 2018; 1864:819-826. [PMID: 30308324 DOI: 10.1016/j.bbalip.2018.10.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2018] [Revised: 09/27/2018] [Accepted: 10/01/2018] [Indexed: 12/17/2022]
Abstract
Group V Phospholipase A2 (Pla2g5) is a member of the PLA2 family of lipid-generating enzymes. It is expressed in immune and non-immune cell types and is inducible during several pathologic conditions serving context-specific functions. In this review, we recapitulate the protective and detrimental functions of Pla2g5 investigated through preclinical and translational approaches. This article is part of a Special Issue entitled Novel functions of phospholipase A2 Guest Editors: Makoto Murakami and Gerard Lambeau.
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Affiliation(s)
- Sachin K Samuchiwal
- Department of Medicine, Harvard Medical School, Division of Rheumatology, Immunology and Allergy, Brigham and Women's Hospital, Boston, MA 02115, USA
| | - Barbara Balestrieri
- Department of Medicine, Harvard Medical School, Division of Rheumatology, Immunology and Allergy, Brigham and Women's Hospital, Boston, MA 02115, USA.
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14
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Selectivity of phospholipid hydrolysis by phospholipase A 2 enzymes in activated cells leading to polyunsaturated fatty acid mobilization. Biochim Biophys Acta Mol Cell Biol Lipids 2018; 1864:772-783. [PMID: 30010011 DOI: 10.1016/j.bbalip.2018.07.002] [Citation(s) in RCA: 73] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Revised: 07/08/2018] [Accepted: 07/10/2018] [Indexed: 12/14/2022]
Abstract
Phospholipase A2s are enzymes that hydrolyze the fatty acid at the sn-2 position of the glycerol backbone of membrane glycerophospholipids. Given the asymmetric distribution of fatty acids within phospholipids, where saturated fatty acids tend to be present at the sn-1 position, and polyunsaturated fatty acids such as those of the omega-3 and omega-6 series overwhelmingly localize in the sn-2 position, the phospholipase A2 reaction is of utmost importance as a regulatory checkpoint for the mobilization of these fatty acids and the subsequent synthesis of proinflammatory omega-6-derived eicosanoids on one hand, and omega-3-derived specialized pro-resolving mediators on the other. The great variety of phospholipase A2s, their differential substrate selectivity under a variety of pathophysiological conditions, as well as the different compartmentalization of each enzyme and accessibility to substrate, render this class of enzymes also key to membrane phospholipid remodeling reactions, and the generation of specific lipid mediators not related with canonical metabolites of omega-6 or omega-3 fatty acids. This review highlights novel findings regarding the selective hydrolysis of phospholipids by phospholipase A2s and the influence this may have on the ability of these enzymes to generate distinct lipid mediators with essential functions in biological processes. This brings a new understanding of the cellular roles of these enzymes depending upon activation conditions.
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15
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Zhang D, Li J, Sun S, Huang C. The inhibitory effect of saPLIγ, a snake sourced PLA 2 inhibitor on carrageenan-induced inflammation in mice. Toxicon 2018; 151:89-95. [PMID: 30003915 DOI: 10.1016/j.toxicon.2018.07.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2018] [Revised: 06/07/2018] [Accepted: 07/05/2018] [Indexed: 12/23/2022]
Abstract
SaPLIγ is a natural phospholipase A2 (PLA2) inhibitor, isolated from Sinonatrix annularis, that has been demonstrated to protect against envenomation by other venomous snakes. As snake venom PLA2s and mammalian secretory PLA2s are similar, saPLIγ is thought to have potential to alleviate inflammatory reactions in which PLA2s act as a key enzyme for arachidonic acid release. The aim of this study was to investigate the anti-inflammatory effects and mechanisms of action of saPLIγ in an animal model of carrageenan-induced acute inflammation. The results indicated that saPLIγ inhibited PLA2 subtypes extensively, especially IIA-PLA2, in a dose-dependent manner. Paw swelling in mice was reduced markedly by intraperitoneal saPLIγ 2.5 mg/kg, and the effect was significantly better than observed with dexamethasone at the same dose. Lower neutrophil infiltration and tissue edema was observed in the paws of saPLIγ-treated mice. Additionally, carrageenan-induced cyclooxygenase-2 (COX-2) and pro-inflammatory cytokines (TNFα and IL-1β) were also significantly down-regulated by saPLIγ in a dose-dependent manner. These results suggested that saPLIγ had effective anti-inflammatory effects in vivo, and these were produced by blocking mammalian IB, IIA, V and X sPLA2 subtypes.
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Affiliation(s)
- Denghong Zhang
- Department of Biochemistry, College of Basic Medical Science, Nanchang University, Jiangxi province, China
| | - Jingjing Li
- Department of Biochemistry, College of Basic Medical Science, Nanchang University, Jiangxi province, China
| | - Shimin Sun
- Department of Biochemistry, College of Basic Medical Science, Nanchang University, Jiangxi province, China
| | - Chunhong Huang
- Department of Biochemistry, College of Basic Medical Science, Nanchang University, Jiangxi province, China.
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16
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Nolin JD, Lai Y, Ogden HL, Manicone AM, Murphy RC, An D, Frevert CW, Ghomashchi F, Naika GS, Gelb MH, Gauvreau GM, Piliponsky AM, Altemeier WA, Hallstrand TS. Secreted PLA2 group X orchestrates innate and adaptive immune responses to inhaled allergen. JCI Insight 2017; 2:94929. [PMID: 29093264 PMCID: PMC5752296 DOI: 10.1172/jci.insight.94929] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Accepted: 09/26/2017] [Indexed: 01/15/2023] Open
Abstract
Phospholipase A2 (PLA2) enzymes regulate the formation of eicosanoids and lysophospholipids that contribute to allergic airway inflammation. Secreted PLA2 group X (sPLA2-X) was recently found to be increased in the airways of asthmatics and is highly expressed in airway epithelial cells and macrophages. In the current study, we show that allergen exposure increases sPLA2-X in humans and in mice, and that global deletion of Pla2g10 results in a marked reduction in airway hyperresponsiveness (AHR), eosinophil and T cell trafficking to the airways, airway occlusion, generation of type-2 cytokines by antigen-stimulated leukocytes, and antigen-specific immunoglobulins. Further, we found that Pla2g10-/- mice had reduced IL-33 levels in BALF, fewer type-2 innate lymphoid cells (ILC2s) in the lung, less IL-33-induced IL-13 expression in mast cells, and a marked reduction in both the number of newly recruited macrophages and the M2 polarization of these macrophages in the lung. These results indicate that sPLA2-X serves as a central regulator of both innate and adaptive immune response to proteolytic allergen.
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Affiliation(s)
- James D. Nolin
- Department of Medicine, Division of Pulmonary and Critical Care
| | - Ying Lai
- Department of Medicine, Division of Pulmonary and Critical Care
| | | | | | - Ryan C. Murphy
- Department of Medicine, Division of Pulmonary and Critical Care
| | - Dowon An
- Department of Medicine, Division of Pulmonary and Critical Care
| | - Charles W. Frevert
- Department of Medicine, Division of Pulmonary and Critical Care
- Department of Comparative Medicine
| | | | | | - Michael H. Gelb
- Department of Chemistry, and
- Department of Biochemistry, University of Washington, Seattle, Washington, USA
| | - Gail M. Gauvreau
- Department of Medicine, McMaster University, Hamilton, Ontario, Canada
| | - Adrian M. Piliponsky
- Center for Immunity and Immunotherapies, Seattle Children’s Research Institute, Seattle, Washington, USA
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17
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Weiler JM, Brannan JD, Randolph CC, Hallstrand TS, Parsons J, Silvers W, Storms W, Zeiger J, Bernstein DI, Blessing-Moore J, Greenhawt M, Khan D, Lang D, Nicklas RA, Oppenheimer J, Portnoy JM, Schuller DE, Tilles SA, Wallace D. Exercise-induced bronchoconstriction update-2016. J Allergy Clin Immunol 2016; 138:1292-1295.e36. [PMID: 27665489 DOI: 10.1016/j.jaci.2016.05.029] [Citation(s) in RCA: 101] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Revised: 05/13/2016] [Accepted: 05/25/2016] [Indexed: 12/26/2022]
Abstract
The first practice parameter on exercise-induced bronchoconstriction (EIB) was published in 2010. This updated practice parameter was prepared 5 years later. In the ensuing years, there has been increased understanding of the pathogenesis of EIB and improved diagnosis of this disorder by using objective testing. At the time of this publication, observations included the following: dry powder mannitol for inhalation as a bronchial provocation test is FDA approved however not currently available in the United States; if baseline pulmonary function test results are normal to near normal (before and after bronchodilator) in a person with suspected EIB, then further testing should be performed by using standardized exercise challenge or eucapnic voluntary hyperpnea (EVH); and the efficacy of nonpharmaceutical interventions (omega-3 fatty acids) has been challenged. The workgroup preparing this practice parameter updated contemporary practice guidelines based on a current systematic literature review. The group obtained supplementary literature and consensus expert opinions when the published literature was insufficient. A search of the medical literature on PubMed was conducted, and search terms included pathogenesis, diagnosis, differential diagnosis, and therapy (both pharmaceutical and nonpharmaceutical) of exercise-induced bronchoconstriction or exercise-induced asthma (which is no longer a preferred term); asthma; and exercise and asthma. References assessed as relevant to the topic were evaluated to search for additional relevant references. Published clinical studies were appraised by category of evidence and used to document the strength of the recommendation. The parameter was then evaluated by Joint Task Force reviewers and then by reviewers assigned by the parent organizations, as well as the general membership. Based on this process, the parameter can be characterized as an evidence- and consensus-based document.
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18
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Murakami M, Yamamoto K, Miki Y, Murase R, Sato H, Taketomi Y. The Roles of the Secreted Phospholipase A 2 Gene Family in Immunology. Adv Immunol 2016; 132:91-134. [PMID: 27769509 PMCID: PMC7112020 DOI: 10.1016/bs.ai.2016.05.001] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Within the phospholipase A2 (PLA2) family that hydrolyzes phospholipids to yield fatty acids and lysophospholipids, secreted PLA2 (sPLA2) enzymes comprise the largest group containing 11 isoforms in mammals. Individual sPLA2s exhibit unique tissue or cellular distributions and enzymatic properties, suggesting their distinct biological roles. Although PLA2 enzymes, particularly cytosolic PLA2 (cPLA2α), have long been implicated in inflammation by driving arachidonic acid metabolism, the precise biological roles of sPLA2s have remained a mystery over the last few decades. Recent studies employing mice gene-manipulated for individual sPLA2s, in combination with mass spectrometric lipidomics to identify their target substrates and products in vivo, have revealed their roles in diverse biological events, including immunity and associated disorders, through lipid mediator-dependent or -independent processes in given microenvironments. In this review, we summarize our current knowledge of the roles of sPLA2s in various immune responses and associated diseases.
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Affiliation(s)
- M Murakami
- Lipid Metabolism Project, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan; AMED-CREST, Japan Agency for Medical Research and Development, Tokyo, Japan.
| | - K Yamamoto
- Lipid Metabolism Project, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan; Faculty of Bioscience and Bioindustry, Tokushima University, Tokushima, Japan
| | - Y Miki
- Lipid Metabolism Project, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan
| | - R Murase
- Lipid Metabolism Project, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan
| | - H Sato
- Lipid Metabolism Project, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan
| | - Y Taketomi
- Lipid Metabolism Project, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan
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19
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Yamaguchi M, Zacharia J, Laidlaw TM, Balestrieri B. PLA2G5 regulates transglutaminase activity of human IL-4-activated M2 macrophages through PGE2 generation. J Leukoc Biol 2016; 100:131-41. [PMID: 26936936 DOI: 10.1189/jlb.3a0815-372r] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2015] [Accepted: 02/12/2016] [Indexed: 12/22/2022] Open
Abstract
Phospholipases A2 are enzymes that liberate membrane-bound lipids in a tissue and cell-specific fashion. Group V secretory phospholipase A2 is necessary for the development of M2 macrophages and their effector functions in a mouse model of the T-helper-2 allergic airway inflammation. However, the function of group V phospholipase A2 in human M2 activation and T-helper-2 inflammation is ill-defined. Transglutaminase-2, a protein cross-linking enzyme, is a newly identified marker of both human and mouse interleukin-4-activated M2 macrophages and is also found in the lungs of patients with asthma. We report that group V phospholipase A2 and transglutaminase-2 colocalized in macrophages of human nasal polyp tissue obtained from patients with T-helper-2 eosinophilic inflammation, and their coexpression positively correlated with the number of eosinophils in each tissue specimen. We demonstrate that in human monocyte-derived macrophages activated by interleukin-4, group V phospholipase A2 translocated and colocalized with transglutaminase-2 in the cytoplasm and on the membrane of macrophages. Moreover, knocking down group V phospholipase A2 with small interfering ribonucleic acid reduced macrophage transglutaminase activity, whereas mass spectrometry analysis of lipids also showed reduced prostaglandin E2 production. Finally, exogenous prostaglandin E2 restored transglutaminase activity of group V phospholipase A2-small interfering ribonucleic acid-treated macrophages. Thus, our study shows a novel function of group V phospholipase A2 in regulating the transglutaminase activity of human interleukin-4-activated M2 macrophages through prostaglandin E2 generation and suggests that group V phospholipase A2 is a functionally relevant enzyme that may have therapeutic value for the treatment of human T-helper-2 inflammatory disorders.
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Affiliation(s)
- Munehiro Yamaguchi
- Department of Medicine, Harvard Medical School, Boston Massachusetts, USA; and the Jeff and Penny Vinik Center for Allergic Disease Research, Division of Rheumatology, Immunology and Allergy, Brigham and Women's Hospital, Boston, Massachusetts, USA
| | - Jennifer Zacharia
- Department of Medicine, Harvard Medical School, Boston Massachusetts, USA; and the Jeff and Penny Vinik Center for Allergic Disease Research, Division of Rheumatology, Immunology and Allergy, Brigham and Women's Hospital, Boston, Massachusetts, USA
| | - Tanya M Laidlaw
- Department of Medicine, Harvard Medical School, Boston Massachusetts, USA; and the Jeff and Penny Vinik Center for Allergic Disease Research, Division of Rheumatology, Immunology and Allergy, Brigham and Women's Hospital, Boston, Massachusetts, USA
| | - Barbara Balestrieri
- Department of Medicine, Harvard Medical School, Boston Massachusetts, USA; and the Jeff and Penny Vinik Center for Allergic Disease Research, Division of Rheumatology, Immunology and Allergy, Brigham and Women's Hospital, Boston, Massachusetts, USA
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20
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Murase R, Sato H, Yamamoto K, Ushida A, Nishito Y, Ikeda K, Kobayashi T, Yamamoto T, Taketomi Y, Murakami M. Group X Secreted Phospholipase A2 Releases ω3 Polyunsaturated Fatty Acids, Suppresses Colitis, and Promotes Sperm Fertility. J Biol Chem 2016; 291:6895-911. [PMID: 26828067 DOI: 10.1074/jbc.m116.715672] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Indexed: 12/31/2022] Open
Abstract
Within the secreted phospholipase A2(sPLA2) family, group X sPLA2(sPLA2-X) has the highest capacity to hydrolyze cellular membranes and has long been thought to promote inflammation by releasing arachidonic acid, a precursor of pro-inflammatory eicosanoids. Unexpectedly, we found that transgenic mice globally overexpressing human sPLA2-X (PLA2G10-Tg) displayed striking immunosuppressive and lean phenotypes with lymphopenia and increased M2-like macrophages, accompanied by marked elevation of free ω3 polyunsaturated fatty acids (PUFAs) and their metabolites. Studies usingPla2g10-deficient mice revealed that endogenous sPLA2-X, which is highly expressed in the colon epithelium and spermatozoa, mobilized ω3 PUFAs or their metabolites to protect against dextran sulfate-induced colitis and to promote fertilization, respectively. In colitis, sPLA2-X deficiency increased colorectal expression of Th17 cytokines, and ω3 PUFAs attenuated their production by lamina propria cells partly through the fatty acid receptor GPR120. In comparison, cytosolic phospholipase A2(cPLA2α) protects from colitis by mobilizing ω6 arachidonic acid metabolites, including prostaglandin E2 Thus, our results underscore a previously unrecognized role of sPLA2-X as an ω3 PUFA mobilizerin vivo, segregated mobilization of ω3 and ω6 PUFA metabolites by sPLA2-X and cPLA2α, respectively, in protection against colitis, and the novel role of a particular sPLA2-X-driven PUFA in fertilization.
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Affiliation(s)
- Remi Murase
- From the Lipid Metabolism Project and School of Pharmacy, Showa University, Tokyo 142-8555, Japan
| | | | | | - Ayako Ushida
- From the Lipid Metabolism Project and Department of Biology, Faculty of Science, Ochanomizu University, Tokyo 112-8610, Japan
| | - Yasumasa Nishito
- Core Technology and Research Center, Tokyo Metropolitan Institute of Medical Science, Tokyo 156-8506, Japan
| | - Kazutaka Ikeda
- Laboratory for Metabolomics, RIKEN Center for Integrative Medical Sciences, Yokohama 230-0045, Japan, and
| | - Tetsuyuki Kobayashi
- Department of Biology, Faculty of Science, Ochanomizu University, Tokyo 112-8610, Japan
| | | | | | - Makoto Murakami
- From the Lipid Metabolism Project and AMED-CREST, Japan Agency for Medical Research and Development, Tokyo 100-0004, Japan
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21
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Rundell KW, Anderson SD, Sue-Chu M, Bougault V, Boulet LP. Air quality and temperature effects on exercise-induced bronchoconstriction. Compr Physiol 2016; 5:579-610. [PMID: 25880506 DOI: 10.1002/cphy.c130013] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Exercise-induced bronchoconstriction (EIB) is exaggerated constriction of the airways usually soon after cessation of exercise. This is most often a response to airway dehydration in the presence of airway inflammation in a person with a responsive bronchial smooth muscle. Severity is related to water content of inspired air and level of ventilation achieved and sustained. Repetitive hyperpnea of dry air during training is associated with airway inflammatory changes and remodeling. A response during exercise that is related to pollution or allergen is considered EIB. Ozone and particulate matter are the most widespread pollutants of concern for the exercising population; chronic exposure can lead to new-onset asthma and EIB. Freshly generated emissions particulate matter less than 100 nm is most harmful. Evidence for acute and long-term effects from exercise while inhaling high levels of ozone and/or particulate matter exists. Much evidence supports a relationship between development of airway disorders and exercise in the chlorinated pool. Swimmers typically do not respond in the pool; however, a large percentage responds to a dry air exercise challenge. Studies support oxidative stress mediated pathology for pollutants and a more severe acute response occurs in the asthmatic. Winter sport athletes and swimmers have a higher prevalence of EIB, asthma and airway remodeling than other athletes and the general population. Because of fossil fuel powered ice resurfacers in ice rinks, ice rink athletes have shown high rates of EIB and asthma. For the athlete training in the urban environment, training during low traffic hours and in low traffic areas is suggested.
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Affiliation(s)
- Kenneth W Rundell
- Department of The Basic Sciences, The Commonwealth Medical College, Scranton, PA, USA
| | - Sandra D Anderson
- Clinical Professor Department of Respiratory and Sleep Medicine, Royal Prince Alfred Hospital, Camperdown, New South Wales, Australia
| | - Malcolm Sue-Chu
- Department of Thoracic Medicine, St Olavs Hospital, Trondheim University Hospital, Department of Circulation and Medical Imaging, Norwegian University of Science and Technology, Trondheim, Norway
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Endogenous secreted phospholipase A2 group X regulates cysteinyl leukotrienes synthesis by human eosinophils. J Allergy Clin Immunol 2015; 137:268-277.e8. [PMID: 26139511 DOI: 10.1016/j.jaci.2015.05.026] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2014] [Revised: 04/23/2015] [Accepted: 05/04/2015] [Indexed: 02/05/2023]
Abstract
BACKGROUND Phospholipase A2s mediate the rate-limiting step in the formation of eicosanoids such as cysteinyl leukotrienes (CysLTs). Group IVA cytosolic PLA2α (cPLA2α) is thought to be the dominant PLA2 in eosinophils; however, eosinophils also have secreted PLA2 (sPLA2) activity that has not been fully defined. OBJECTIVES To examine the expression of sPLA2 group X (sPLA2-X) in eosinophils, the participation of sPLA2-X in the formation of CysLTs, and the mechanism by which sPLA2-X initiates the synthesis of CysLTs in eosinophils. METHODS Peripheral blood eosinophils were obtained from volunteers with asthma and/or allergy. A rabbit polyclonal anti-sPLA2-X antibody identified sPLA2-X by Western blot. We used confocal microscopy to colocalize the sPLA2-X to intracellular structures. An inhibitor of sPLA2-X (ROC-0929) that does not inhibit other mammalian sPLA2s, as well as inhibitors of the mitogen-activated kinase cascade (MAPK) and cPLA2α, was used to examine the mechanism of N-formyl-methionyl-leucyl-phenylalanine (fMLP)-mediated formation of CysLT. RESULTS Eosinophils express the mammalian sPLA2-X gene (PLA2G10). The sPLA2-X protein is located in the endoplasmic reticulum, golgi, and granules of eosinophils and moves to the granules and lipid bodies during fMLP-mediated activation. Selective sPLA2-X inhibition attenuated the fMLP-mediated release of arachidonic acid and CysLT formation by eosinophils. Inhibitors of p38, extracellular-signal-regulated kinases 1/2 (p44/42 MAPK), c-Jun N-terminal kinase, and cPLA2α also attenuated the fMLP-mediated formation of CysLT. The sPLA2-X inhibitor reduced the phosphorylation of p38 and extracellular-signal-regulated kinases 1/2 (p44/42 MAPK) as well as cPLA2α during cellular activation, indicating that sPLA2-X is involved in activating the MAPK cascade leading to the formation of CysLT via cPLA2α. We further demonstrate that sPLA2-X is activated before secretion from the cell during activation. Short-term priming with IL-13 and TNF/IL-1β increased the expression of PLA2G10 by eosinophils. CONCLUSIONS These results demonstrate that sPLA2-X plays a significant role in the formation of CysLTs by human eosinophils. The predominant role of the enzyme is the regulation of MAPK activation that leads to the phosphorylation of cPLA2α. The sPLA2-X protein is regulated by proteolytic cleavage, suggesting that an inflammatory environment may promote the formation of CysLTs through this mechanism. These results have important implications for the treatment of eosinophilic disorders such as asthma.
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23
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Loxham M, Davies DE, Blume C. Epithelial function and dysfunction in asthma. Clin Exp Allergy 2015; 44:1299-313. [PMID: 24661647 DOI: 10.1111/cea.12309] [Citation(s) in RCA: 75] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2013] [Revised: 03/06/2014] [Accepted: 03/19/2014] [Indexed: 12/15/2022]
Abstract
Asthma was previously defined as an allergic Th2-mediated inflammatory immune disorder. Recently, this paradigm has been challenged because not all pathological changes observed in the asthmatic airways are adequately explained simply as a result of Th2-mediated processes. Contemporary thought holds that asthma is a complex immune disorder involving innate as well as adaptive immune responses, with the clinical heterogeneity of asthma perhaps a result of the different relative contribution of these two systems to the disease. Epidemiological studies show that exposure to certain environmental substances is strongly associated with the risk of developing asthma. The airway epithelium is first barrier to interact with, and respond to, environmental agents (pollution, viral infection, allergens), suggesting that it is a key player in the pathology of asthma. Epithelial cells play a key role in the regulation of tissue homeostasis by the modulation of numerous molecules, from antioxidants and lipid mediators to growth factors, cytokines, and chemokines. Additionally, the epithelium is also able to suppress mechanisms involved in, for example, inflammation in order to maintain homeostasis. An intrinsic alteration or defect in these regulation mechanisms compromises the epithelial barrier, and therefore, the barrier may be more prone to environmental substances and thus more likely to exhibit an asthmatic phenotype. In support of this, polymorphisms in a number of genes that are expressed in the bronchial epithelium have been linked to asthma susceptibility, while environmental factors may affect epigenetic mechanisms that can alter epithelial function and response to environmental insults. A detailed understanding of the regulatory role of the airway epithelium is required to develop new therapeutic strategies for asthma that not only address the symptoms but also the underlining pathogenic mechanism(s) and prevent airway remodelling.
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Affiliation(s)
- M Loxham
- Academic Unit of Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, University Hospital Southampton, Southampton, Hampshire, UK
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24
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Trian T, Allard B, Dupin I, Carvalho G, Ousova O, Maurat E, Bataille J, Thumerel M, Begueret H, Girodet PO, Marthan R, Berger P. House dust mites induce proliferation of severe asthmatic smooth muscle cells via an epithelium-dependent pathway. Am J Respir Crit Care Med 2015; 191:538-46. [PMID: 25569771 DOI: 10.1164/rccm.201409-1582oc] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
RATIONALE Asthma is a frequent airway disease, and asthma control determinants have been associated with indoor allergen sensitization. The most frequent allergens are house dust mites (HDM), which act in vivo on the bronchial epithelial layer. Severe asthma has also been associated with bronchial remodeling and more specifically with increased mass of bronchial smooth muscle (BSM). However, the relationship between HDM stimulation of the bronchial epithelial layer and BSM remodeling is unknown. OBJECTIVES To evaluate whether epithelial stimulation with HDM induces BSM cell proliferation in subjects with severe asthma. METHODS A total of 22 subjects with severe asthma and 27 subjects with no asthma were recruited. We have developed an in vitro culture model combining an epithelium layer in air-liquid interface (ALI) interacting with BSM. We assessed BSM proliferation using BrdU incorporation. We explored the role of epithelium-derived mediators using reverse-transcriptase polymerase chain reaction (RT-PCR) and ELISA in vitro and in vivo. Finally, leukotrienes receptor expression was assessed in vitro by flow cytometry and RT-PCR and ex vivo by laser microdissection and RT-PCR. MEASUREMENTS AND MAIN RESULTS We found that epithelial stimulation by HDM selectively increased the proliferation of asthmatic BSM cells and not that of nonasthmatic cells. The mechanism involved epithelial protease-activated receptor-2-dependent production of leukotrienes C4 associated with an overexpression of leukotrienes receptor CysLTR1 by asthmatic BSM cells in vitro and ex vivo. CONCLUSIONS This work demonstrates the selective role of HDM on BSM remodeling in patients with severe asthma and points out different therapeutic targets at epithelial and smooth muscle levels.
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Murakami M, Sato H, Miki Y, Yamamoto K, Taketomi Y. A new era of secreted phospholipase A₂. J Lipid Res 2015; 56:1248-61. [PMID: 25805806 DOI: 10.1194/jlr.r058123] [Citation(s) in RCA: 161] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Indexed: 12/18/2022] Open
Abstract
Among more than 30 members of the phospholipase A2 (PLA2) superfamily, secreted PLA2 (sPLA2) enzymes represent the largest family, being Ca(2+)-dependent low-molecular-weight enzymes with a His-Asp catalytic dyad. Individual sPLA2s exhibit unique tissue and cellular distributions and enzymatic properties, suggesting their distinct biological roles. Recent studies using transgenic and knockout mice for nearly a full set of sPLA2 subtypes, in combination with sophisticated lipidomics as well as biochemical and cell biological studies, have revealed distinct contributions of individual sPLA2s to various pathophysiological events, including production of pro- and anti-inflammatory lipid mediators, regulation of membrane remodeling, degradation of foreign phospholipids in microbes or food, or modification of extracellular noncellular lipid components. In this review, we highlight the current understanding of the in vivo functions of sPLA2s and the underlying lipid pathways as revealed by a series of studies over the last decade.
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Affiliation(s)
- Makoto Murakami
- Lipid Metabolism Project, Tokyo Metropolitan Institute of Medical Science, Tokyo 156-8506, Japan CREST, Japan Science and Technology Agency, Saitama 332-0012, Japan
| | - Hiroyasu Sato
- Lipid Metabolism Project, Tokyo Metropolitan Institute of Medical Science, Tokyo 156-8506, Japan
| | - Yoshimi Miki
- Lipid Metabolism Project, Tokyo Metropolitan Institute of Medical Science, Tokyo 156-8506, Japan
| | - Kei Yamamoto
- Lipid Metabolism Project, Tokyo Metropolitan Institute of Medical Science, Tokyo 156-8506, Japan
| | - Yoshitaka Taketomi
- Lipid Metabolism Project, Tokyo Metropolitan Institute of Medical Science, Tokyo 156-8506, Japan
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Murakami M, Taketomi Y. Secreted phospholipase A2 and mast cells. Allergol Int 2015; 64:4-10. [PMID: 25572553 DOI: 10.1016/j.alit.2014.07.005] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2014] [Accepted: 07/18/2014] [Indexed: 12/24/2022] Open
Abstract
Phospholipase A2s (PLA2s) are a group of enzymes that hydrolyze the sn-2 position of phospholipids to release (typically unsaturated) fatty acids and lysophospholipids, which serve as precursors for a variety of bioactive lipid mediators. Among the PLA2 superfamily, secreted PLA2 (sPLA2) enzymes comprise the largest subfamily that includes 11 isoforms with a conserved His-Asp catalytic dyad. Individual sPLA2 enzymes exhibit unique tissue and cellular localizations and specific enzymatic properties, suggesting their distinct biological roles. Recent studies using transgenic and knockout mice for individual sPLA2 isofoms have revealed their involvement in various pathophysiological events. Here, we overview the current state of knowledge about sPLA2s, specifically their roles in mast cells (MCs) in the context of allergology. In particular, we highlight group III sPLA2 (PLA2G3) as an "anaphylactic sPLA2" that promotes MC maturation and thereby anaphylaxis through a previously unrecognized lipid-orchestrated circuit.
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Affiliation(s)
- Makoto Murakami
- Lipid Metabolism Project, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan; CREST, Japan Science and Technology Agency, Saitama, Japan.
| | - Yoshitaka Taketomi
- Lipid Metabolism Project, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan
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Claar D, Hartert TV, Peebles RS. The role of prostaglandins in allergic lung inflammation and asthma. Expert Rev Respir Med 2014; 9:55-72. [PMID: 25541289 DOI: 10.1586/17476348.2015.992783] [Citation(s) in RCA: 84] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Prostaglandins (PGs) are products of the COX pathway of arachidonic acid metabolism. There are five primary PGs, PGD₂, PGE₂, PGF₂, PGI₂ and thromboxane A₂, all of which signal through distinct seven transmembrane, G-protein coupled receptors. Some PGs may counteract the actions of others, or even the same PG may have opposing physiologic or immunologic effects, depending on the specific receptor through which it signals. In this review, we examine the effects of COX activity and the various PGs on allergic airway inflammation and physiology that is associated with asthma. We also highlight the potential therapeutic benefit of targeting PGs in allergic lung inflammation and asthma based on basic science, animal model and human studies.
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Affiliation(s)
- Dru Claar
- Department of Medicine, Division of Allergy, Pulmonary, and Critical Care Medicine, T-1217 MCN Vanderbilt University Medical Center, Vanderbilt University School of Medicine, Nashville, TN 37232-2650, USA
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Murakami M, Taketomi Y, Miki Y, Sato H, Yamamoto K, Lambeau G. Emerging roles of secreted phospholipase A2 enzymes: the 3rd edition. Biochimie 2014; 107 Pt A:105-13. [PMID: 25230085 DOI: 10.1016/j.biochi.2014.09.003] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2014] [Accepted: 09/05/2014] [Indexed: 12/19/2022]
Abstract
Within the phospholipase A2 (PLA2) superfamily, secreted PLA2 (sPLA2) enzymes comprise the largest family that contains 11 to 12 mammalian isoforms with a conserved His-Asp catalytic dyad. Individual sPLA2s exhibit unique tissue and cellular localizations and specific enzymatic properties, suggesting distinct biological roles. Individual sPLA2s are involved in diverse biological events through lipid mediator-dependent or -independent processes and act redundantly or non-redundantly in a given microenvironment. In the past few years, new biological aspects of sPLA2s have been clarified using their transgenic and knockout mouse lines in combination with mass spectrometric lipidomics to unveil their target substrates and products in vivo. In the 3rd edition of this review series, we highlight the newest understanding of the in vivo functions of sPLA2s in pathophysiological conditions in the context of immunity and metabolism. We will also describe the latest knowledge on PLA2R1, the best known sPLA2 receptor, which may serve either as a clearance or signaling receptor for sPLA2 or may even act independently of sPLA2 function.
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Affiliation(s)
- Makoto Murakami
- Lipid Metabolism Project, The Tokyo Metropolitan Institute of Medical Science, 2-1-6 Kamikitazawa, Setagaya-ku, Tokyo 156-8506, Japan; CREST, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan.
| | - Yoshitaka Taketomi
- Lipid Metabolism Project, The Tokyo Metropolitan Institute of Medical Science, 2-1-6 Kamikitazawa, Setagaya-ku, Tokyo 156-8506, Japan
| | - Yoshimi Miki
- Lipid Metabolism Project, The Tokyo Metropolitan Institute of Medical Science, 2-1-6 Kamikitazawa, Setagaya-ku, Tokyo 156-8506, Japan
| | - Hiroyasu Sato
- Lipid Metabolism Project, The Tokyo Metropolitan Institute of Medical Science, 2-1-6 Kamikitazawa, Setagaya-ku, Tokyo 156-8506, Japan
| | - Kei Yamamoto
- Lipid Metabolism Project, The Tokyo Metropolitan Institute of Medical Science, 2-1-6 Kamikitazawa, Setagaya-ku, Tokyo 156-8506, Japan
| | - Gérard Lambeau
- Institut de Pharmacologie Moléculaire et Cellulaire, UMR 7275, Centre National de la Recherche Scientifique - Université Nice Sophia Antipolis, Valbonne 06560, France
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The step further to understand the role of cytosolic phospholipase A2 alpha and group X secretory phospholipase A2 in allergic inflammation: pilot study. BIOMED RESEARCH INTERNATIONAL 2014; 2014:670814. [PMID: 25247183 PMCID: PMC4163415 DOI: 10.1155/2014/670814] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/27/2014] [Revised: 08/11/2014] [Accepted: 08/11/2014] [Indexed: 11/18/2022]
Abstract
Allergens, viral, and bacterial infections are responsible for asthma exacerbations that occur with progression of airway inflammation. cPLA2α and sPLA2X are responsible for delivery of arachidonic acid for production of eicosanoids—one of the key mediators of airway inflammation. However, cPLA2α and sPLA2X role in allergic inflammation has not been fully elucidated. The aim of this study was to analyze the influence of rDer p1 and rFel d1 and lipopolysaccharide (LPS) on cPLA2α expression and sPLA2X secretion in PBMC of asthmatics and in A549 cell line. PBMC isolated from 14 subjects, as well as A549 cells, were stimulated with rDer p1, rFel d1, and LPS. Immunoblotting technique was used to study the changes in cPLA2α protein expression and ELISA was used to analyze the release of sPLA2X. PBMC of asthmatics released more sPLA2X than those from healthy controls in the steady state. rDer p1 induced more sPLA2X secretion than cPLA2α protein expression. rFel d1 caused decrease in cPLA2α relative expression in PBMC of asthmatics and in A549 cells. Summarizing, Der p1 and Fel d1 involve phospholipase A2 enzymes in their action. sPLA2X seems to be one of important PLA2 isoform in allergic inflammation, especially caused by house dust mite allergens.
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Hallstrand TS, Lai Y, Altemeier WA, Appel CL, Johnson B, Frevert CW, Hudkins KL, Bollinger JG, Woodruff PG, Hyde DM, Henderson WR, Gelb MH. Regulation and function of epithelial secreted phospholipase A2 group X in asthma. Am J Respir Crit Care Med 2013; 188:42-50. [PMID: 23614662 PMCID: PMC3735246 DOI: 10.1164/rccm.201301-0084oc] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2013] [Accepted: 04/08/2013] [Indexed: 11/16/2022] Open
Abstract
RATIONALE Indirect airway hyperresponsiveness (AHR) is a fundamental feature of asthma that is manifest as exercise-induced bronchoconstriction (EIB). Secreted phospholipase A2 group X (sPLA2-X) plays a key role in regulating eicosanoid formation and the development of inflammation and AHR in murine models. OBJECTIVES We sought to examine sPLA2-X in the airway epithelium and airway wall of patients with asthma, the relationship to AHR in humans, and the regulation and function of sPLA2-X within the epithelium. METHODS We precisely phenotyped 34 patients with asthma (19 with and 15 without EIB) and 10 normal control subjects to examine in vivo differences in epithelial gene expression, quantitative morphometry of endobronchial biopsies, and levels of secreted protein. The regulation of sPLA2-X gene (PLA2G10) expression was examined in primary airway epithelial cell cultures. The function of epithelial sPLA2-X in eicosanoid formation was examined using PLA2 inhibitors and murine tracheal epithelial cells with Pla2g10 deletion. MEASUREMENTS AND MAIN RESULTS We found that sPLA2-X protein is increased in the airways of patients with asthma and that epithelial-derived sPLA2-X may be increased in association with indirect AHR. The expression of sPLA2-X increases during in vitro epithelial differentiation; is regulated by inflammatory signals including tumor necrosis factor, IL-13, and IL-17; and is both secreted from the epithelium and directly participates in the release of arachidonic acid by epithelial cells. CONCLUSIONS These data reveal a relationship between epithelial-derived sPLA2-X and indirect AHR in asthma and that sPLA2-X serves as an epithelial regulator of inflammatory eicosanoid formation. Therapies targeting epithelial sPLA2-X may be useful in asthma.
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Hallstrand TS, Lai Y, Henderson WR, Altemeier WA, Gelb MH. Epithelial regulation of eicosanoid production in asthma. Pulm Pharmacol Ther 2013; 25:432-7. [PMID: 23323271 DOI: 10.1016/j.pupt.2012.02.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Alterations in the airway epithelium have been associated with the development of asthma in elite athletes and in subjects that are susceptible to exercise-induced bronchoconstriction (EIB). The syndrome of EIB refers to acute airflow obstruction that is triggered by a period of physical exertion. Asthmatics who are susceptible to EIB have increased levels of cysteinyl leukotrienes (CysLTs, i.e., LTs C₄, D₄, and E₄) in induced sputum and exhaled breath condensate, and greater shedding of epithelial cells into the airway lumen. Exercise challenge in individuals susceptible to this disorder initiates a sustained increase in CysLTs in the airways, and secreted mucin release and smooth muscle constriction, which may be mediated in part through activation of sensory nerves. We have identified a secreted phospholipase A₂ (sPLA₂) with increased levels in the airways of patients with EIB called sPLA₂ group X(sPLA₂-X).We have found that sPLA₂-X is strongly expressed in the airway epithelium in asthma. Further,we discovered that transglutaminase 2 (TGM2) is expressed at increased levels in asthma and serves asa regulator of sPLA₂-X. Finally, we demonstrated that sPLA₂-X acts on target cells such as eosinophils to initiate cellular eicosanoid synthesis. Collectively, these studies identify a novel mechanism linking the airway epithelium to the production of inflammatory eicosanoids by leukocytes.
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Affiliation(s)
- Teal S Hallstrand
- Division of Pulmonary and Critical Care, University of Washington, Box 356522, 1959 NE Pacific Street, Seattle, WA 98195, USA.
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Pniewska E, Pawliczak R. The involvement of phospholipases A2 in asthma and chronic obstructive pulmonary disease. Mediators Inflamm 2013; 2013:793505. [PMID: 24089590 PMCID: PMC3780701 DOI: 10.1155/2013/793505] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2012] [Revised: 01/02/2013] [Accepted: 02/27/2013] [Indexed: 12/21/2022] Open
Abstract
The increased morbidity, mortality, and ineffective treatment associated with the pathogenesis of chronic inflammatory diseases such as asthma and chronic obstructive pulmonary disease (COPD) have generated much research interest. The key role is played by phospholipases from the A2 superfamily: enzymes which are involved in inflammation through participation in pro- and anti-inflammatory mediators production and have an impact on many immunocompetent cells. The 30 members of the A2 superfamily are divided into 7 groups. Their role in asthma and COPD has been studied in vitro and in vivo (animal models, cell cultures, and patients). This paper contains complete and updated information about the involvement of particular enzymes in the etiology and course of asthma and COPD.
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Affiliation(s)
- Ewa Pniewska
- Department of Immunopathology, Faculty of Biomedical Sciences and Postgraduate Training, Medical University of Lodz, 7/9 Zeligowskiego Street, Building 2, Room 122, 90-752 Lodz, Poland
| | - Rafal Pawliczak
- Department of Immunopathology, Faculty of Biomedical Sciences and Postgraduate Training, Medical University of Lodz, 7/9 Zeligowskiego Street, Building 2, Room 122, 90-752 Lodz, Poland
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Mickleborough TD, Vaughn CL, Shei RJ, Davis EM, Wilhite DP. Marine lipid fraction PCSO-524 (lyprinol/omega XL) of the New Zealand green lipped mussel attenuates hyperpnea-induced bronchoconstriction in asthma. Respir Med 2013; 107:1152-63. [PMID: 23660397 DOI: 10.1016/j.rmed.2013.04.010] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/12/2013] [Revised: 04/09/2013] [Accepted: 04/10/2013] [Indexed: 02/06/2023]
Abstract
PURPOSE Evaluate the effect of the marine lipid fraction of the New Zealand green-lipped mussel (Perna canaliculus) PCSO-524 (Lyprinol/Omega XL), rich in omega-3 fatty acids, on airway inflammation and the bronchoconstrictor response to eucapnic voluntary hyperpnea (EVH) in asthmatics. METHODS Twenty asthmatic subjects, with documented HIB, participated in a placebo controlled double-blind randomized crossover trial. Subjects entered the study on their usual diet and were then placed on 3 weeks of PCSO-524 or placebo supplementation, followed by a 2 week washout period, before crossing over to the alternative diet. Pre- and post-eucapnic voluntary hyperpnea (EVH) pulmonary function, fraction of exhaled nitric oxide (FENO), asthma symptom scores, medication use, exhaled breath condensate (EBC) pH, cysteinyl leukotrienes (cyst-LT), 8-isoprostane and urinary 9α, 11β-prostaglandin (PG)F2 and Clara (CC16) protein concentrations were assessed at the beginning of the trial and at the end of each treatment period. RESULTS The PCSO-524 diet significantly reduced (p < 0.05) the maximum fall in post-EVH FEV1 (-8.4 ± 3.2%) compared to usual (-19.3 ± 5.4%) and placebo diet (-22.5 ± 13.7%). Pre- and post- EVH EBC cyst-LT and 8-isoprostane, and urinary 9α, 11β-PGF2 and CC16 concentrations were significantly reduced (p < 0.05) on the PCSO-524 diet compared to the usual and placebo diet. EBC pH and asthma symptom scores were significantly improved (p < 0.05) and rescue medication use significantly reduced (p < 0.05) on the PCSO-524 diet compared to the usual and placebo diet. CONCLUSION PCSO-524 (Lyprinol)/Omega XL) may have beneficial effects in HIB and asthma by serving as a pro-resolving agonist and/or inflammatory antagonist.
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Affiliation(s)
- Timothy D Mickleborough
- School of Public Health-Bloomington, Department of Kinesiology, Human Performance and Exercise Biochemistry Laboratory, 1025 E. 7th St. SPH 112, Bloomington, IN 47404, USA.
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Hallstrand TS, Kippelen P, Larsson J, Bougault V, van Leeuwen JC, Driessen JMM, Brannan JD. Where to from here for exercise-induced bronchoconstriction: the unanswered questions. Immunol Allergy Clin North Am 2013; 33:423-42, ix. [PMID: 23830134 DOI: 10.1016/j.iac.2013.02.010] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The role of epithelial injury is an unanswered question in those with established asthma and in elite athletes who develop features of asthma and exercise-induced bronchorestriction (EIB) after years of training. The movement of water in response to changes in osmolarity is likely to be an important signal to the epithelium that may be central to the onset of EIB. It is generally accepted that the mast cell and its mediators play a major role in EIB and the presence of eosinophils is likely to enhance EIB severity.
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Affiliation(s)
- Teal S Hallstrand
- Division of Pulmonary and Critical Care, University of Washington, Department of Medicine, 1959 NE Pacific Street, Box 356166, Seattle, WA 98195-6522, USA.
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Role of cells and mediators in exercise-induced bronchoconstriction. Immunol Allergy Clin North Am 2013; 33:313-28, vii. [PMID: 23830127 DOI: 10.1016/j.iac.2013.02.003] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
A susceptible group of subjects with asthma develops airflow obstruction in response to the transfer of water out of the airways during exercise. The transfer of water or the challenge with a hypertonic solution serves as a strong stimulus to the airway epithelium. Susceptible subjects have epithelial shedding into the airway lumen, and airway inflammation that leads to the overproduction of leukotrienes and other eicosanoids following exercise challenge. The sensory nerves of the airways may serve as a critical link that mediates the effect of eicosanoids, leading to bronchoconstriction and mucus production in response to exercise challenge.
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Sun J, Dahlén B, Agerberth B, Haeggström JZ. The antimicrobial peptide LL-37 induces synthesis and release of cysteinyl leukotrienes from human eosinophils--implications for asthma. Allergy 2013; 68:304-11. [PMID: 23330796 DOI: 10.1111/all.12087] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/28/2012] [Indexed: 12/12/2022]
Abstract
BACKGROUND Eosinophils and their products, including leukotrienes and eosinophil cationic protein (ECP), are well-known mediators of inflammation and tissue damage in asthma. The antimicrobial peptide LL-37 exhibits a variety of immunomodulatory activities. However, the role of LL-37 in asthma has not been fully addressed. Here, we aim to investigate the effect of LL-37 on inducing inflammatory mediators in human eosinophils, probe the underlying mechanisms, and search for a clinical correlate. METHODS Primary eosinophils were isolated from peripheral blood. Leukotriene and ECP levels were measured using EIAs or ELISAs. Activation of leukotriene-synthesizing enzymes and signaling kinases was analyzed by Western blot or immunofluorescent imaging. LL-37/its proform hCAP18 expression was analyzed by Western blot. RESULTS LL-37, via formyl peptide receptor-2 (FPR-2), triggered the release of cysteinyl leukotrienes (cys-LTs) from eosinophils. The release was more prominent in cells primed with the eosinophilopoietic cytokine GM-CSF or IL-5 or cells from asthmatic patients. LL-37 stimulates lipid body formation and activates cys-LT-synthesizing enzymes by multiple mechanisms: enhancing cPLA(2) activity by pERK1/2-mediated phosphorylation and inducing intracellular translocation and assembly of 5-LO and LTC(4) S at perinuclear locations and lipid bodies. In addition to cys-LTs, LL-37 enhances ECP release from eosinophils via pERK1/2. The expression of hCAP18 and its release following leukotriene stimulation are significantly higher in eosinophils from asthmatics. CONCLUSIONS This study identifies LL-37 as an eosinophil-activating peptide that triggers release of inflammatory mediators. The clinical correlation suggests that LL-37/hCAP18 and its signaling pathway represent potential therapeutic targets for this disease.
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Affiliation(s)
- J. Sun
- Division of Physiological Chemistry II; Department of Medical Biochemistry and Biophysics; Karolinska Institutet; Stockholm; Sweden
| | | | - B. Agerberth
- Division of Physiological Chemistry II; Department of Medical Biochemistry and Biophysics; Karolinska Institutet; Stockholm; Sweden
| | - J. Z. Haeggström
- Division of Physiological Chemistry II; Department of Medical Biochemistry and Biophysics; Karolinska Institutet; Stockholm; Sweden
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37
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Emerging roles of secreted phospholipase A2 enzymes: An update. Biochimie 2013; 95:43-50. [DOI: 10.1016/j.biochi.2012.09.007] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2012] [Accepted: 09/11/2012] [Indexed: 01/18/2023]
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New insights into pathogenesis of exercise-induced bronchoconstriction. Curr Opin Allergy Clin Immunol 2012; 12:42-8. [PMID: 22157157 DOI: 10.1097/aci.0b013e32834ecc67] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE OF REVIEW Exercise-induced bronchoconstriction (EIB) refers to acute airflow obstruction that is triggered by a period of physical exertion. Here we review recent findings about the epidemiology of EIB, immunopathology leading to EIB, and the latest understanding of the pathogenesis of EIB. RECENT FINDINGS Longitudinal studies demonstrated that airway hyper-responsiveness to exercise or cold air at an early age are among the strongest predictors of persistent asthma. Patients that are susceptible to EIB have epithelial disruption and increased levels of inflammatory eicosanoids such as cysteinyl leukotrienes (CysLT)s. The leukocytes implicated in production of eicosanoids in the airways include both a unique mast cell population as well as eosinophils. A secreted phospholipase A(2) (sPLA(2)) enzyme that serves as a regulator of CysLT formation is present in increased quantities in asthma. Transglutaminase 2 (TGM2) is expressed at increased levels in asthma and serves as a regulator of secreted phospholipase A(2) group X (sPLA(2)-X). Further, sPLA(2)-X acts on target cells such as eosinophils to initiate cellular eicosanoid synthesis. SUMMARY Recent studies have advanced our understanding of EIB as a syndrome that is caused by the increased production of inflammatory eicosanoids. The airway epithelium may be an important regulator of the production of inflammatory eicosanoids by leukocytes.
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Tebbutt SJ, He JQ, Singh A, Shannon CP, Ruan J, Carlsten C. Transcriptional Changes of Blood Eosinophils After Methacholine Inhalation Challenge in Asthmatics. GENOMICS INSIGHTS 2012. [PMID: 26217105 PMCID: PMC4510604 DOI: 10.4137/gei.s9125] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Background Methacholine challenge is commonly used within the asthma diagnostic algorithm. Methacholine challenge has recently been shown to induce airway remodelling in asthma via bronchoconstriction, without additional airway inflammation. We evaluated the effect of methacholine-induced bronchoconstriction on the peripheral whole-blood transcriptome. Methods Fourteen males with adult-onset, occupational asthma, 26–77 years of age, underwent methacholine inhalation challenges. The concentration of methacholine eliciting a ≥20% fall in FEV1 (PC20) was determined. Blood was collected immediately prior to and two hours after challenge. Complete blood counts and leukocyte differentials were obtained. Transcriptome analysis was performed using Affymetrix GeneChip® Human Gene 1.0 ST arrays. Data were analyzed using robust LIMMA and SAM. The cell-specific Significance Analysis of Microarrays (csSAM) algorithm was used to deconvolute the gene expression data according to cell type. Results Microarray pathway analysis indicated that inflammatory processes were differentially affected. CsSAM identified 1,559 transcripts differentially expressed (all down-regulated) between pre- and post-methacholine in eosinophils at a false discovery cutoff of 10%. Notable changes included the GOLGA5 and METTL2B genes and the protein ubiquitination and CCR3 pathways. Conclusions We demonstrated significant changes in the peripheral blood eosinophil-specific transcriptome of asthmatics two hours after methacholine challenge. CCR3 and protein ubiquitination pathways are both significantly down-regulated.
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Affiliation(s)
- Scott J Tebbutt
- James Hogg Research Centre, St. Paul's Hospital, University of British Columbia, Vancouver, British Columbia, Canada. ; Institute for HEART+LUNG Health, Vancouver, BC, Canada. ; Department of Medicine, Division of Respiratory Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Jian-Qing He
- James Hogg Research Centre, St. Paul's Hospital, University of British Columbia, Vancouver, British Columbia, Canada. ; Institute for HEART+LUNG Health, Vancouver, BC, Canada
| | - Amrit Singh
- James Hogg Research Centre, St. Paul's Hospital, University of British Columbia, Vancouver, British Columbia, Canada. ; Institute for HEART+LUNG Health, Vancouver, BC, Canada
| | - Casey P Shannon
- James Hogg Research Centre, St. Paul's Hospital, University of British Columbia, Vancouver, British Columbia, Canada. ; Institute for HEART+LUNG Health, Vancouver, BC, Canada
| | - Jian Ruan
- James Hogg Research Centre, St. Paul's Hospital, University of British Columbia, Vancouver, British Columbia, Canada. ; Institute for HEART+LUNG Health, Vancouver, BC, Canada
| | - Chris Carlsten
- Institute for HEART+LUNG Health, Vancouver, BC, Canada. ; Department of Medicine, Division of Respiratory Medicine, University of British Columbia, Vancouver, BC, Canada. ; Vancouver Coastal Health Research Institute, Vancouver General Hospital, Vancouver, BC, Canada
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40
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Jemel I, Ii H, Oslund RC, Payré C, Dabert-Gay AS, Douguet D, Chargui K, Scarzello S, Gelb MH, Lambeau G. Group X secreted phospholipase A2 proenzyme is matured by a furin-like proprotein convertase and releases arachidonic acid inside of human HEK293 cells. J Biol Chem 2011; 286:36509-21. [PMID: 21878635 DOI: 10.1074/jbc.m111.268540] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Among mammalian secreted phospholipases A(2) (sPLA(2)s), group X sPLA(2) has the most potent hydrolyzing activity toward phosphatidylcholine and is involved in arachidonic acid (AA) release. Group X sPLA(2) is produced as a proenzyme and contains a short propeptide of 11 amino acids ending with a dibasic motif, suggesting cleavage by proprotein convertases. Although the removal of this propeptide is clearly required for enzymatic activity, the cellular location and the protease(s) involved in proenzyme conversion are unknown. Here we have analyzed the maturation of group X sPLA(2) in HEK293 cells, which have been extensively used to analyze sPLA(2)-induced AA release. Using recombinant mouse (PromGX) and human (ProhGX) proenzymes; HEK293 cells transfected with cDNAs coding for full-length ProhGX, PromGX, and propeptide mutants; and various permeable and non-permeable sPLA(2) inhibitors and protease inhibitors, we demonstrate that group X sPLA(2) is mainly converted intracellularly and releases AA before externalization from the cell. Most strikingly, the exogenous proenzyme does not elicit AA release, whereas the transfected proenzyme does elicit AA release in a way insensitive to non-permeable sPLA(2) inhibitors. In transfected cells, a permeable proprotein convertase inhibitor, but not a non-permeable one, prevents group X sPLA(2) maturation and partially blocks AA release. Mutations at the dibasic motif of the propeptide indicate that the last basic residue is required and sufficient for efficient maturation and AA release. All together, these results argue for the intracellular maturation of group X proenzyme in HEK293 cells by a furin-like proprotein convertase, leading to intracellular release of AA during secretion.
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Affiliation(s)
- Ikram Jemel
- Institut de Pharmacologie Moléculaire et Cellulaire, UMR6097, CNRS et Université de Nice-Sophia-Antipolis, 660 Route des Lucioles, Sophia Antipolis, 06560 Valbonne, France
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41
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Abstract
Current therapy for asthma is highly effective. β(2)-Adrenergic receptor (β(2)AR) agonists are the most effective bronchodilators and relax airway smooth muscle cells through increased cAMP concentrations and directly opening large conductance Ca(2+) channels. β(2)AR may also activate alternative signaling pathways that may have detrimental effects in asthma. Glucocorticoids are the most effective anti-inflammatory treatments and switch off multiple activated inflammatory genes through recruitment of histone deacetylase-2, activating anti-inflammatory genes, and through increasing mRNA stability of inflammatory genes. There are beneficial molecular interactions between β(2)AR and glucocorticoid-activated pathways. Understanding these signaling pathways may lead to even more effective therapies in the future.
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Affiliation(s)
- Peter J Barnes
- National Heart and Lung Institute, Imperial College, London SW3 6LY, United Kingdom.
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42
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Murakami M, Taketomi Y, Sato H, Yamamoto K. Secreted phospholipase A2 revisited. J Biochem 2011; 150:233-55. [PMID: 21746768 DOI: 10.1093/jb/mvr088] [Citation(s) in RCA: 150] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Phospholipase A(2) (PLA(2)) catalyses the hydrolysis of the sn-2 position of glycerophospholipids to yield fatty acids and lysophospholipids. So far, more than 30 enzymes that possess PLA(2) or related activity have been identified in mammals. About one third of these enzymes belong to the secreted PLA(2) (sPLA(2)) family, which comprises low molecular weight, Ca(2+) requiring, secreted enzymes with a His/Asp catalytic dyad. Individual sPLA(2)s display distinct localizations and enzymatic properties, suggesting their specialized biological roles. However, in contrast to intracellular PLA(2)s, whose roles in signal transduction and membrane homoeostasis have been well documented, the biological roles of sPLA(2)s in vivo have remained obscure until recently. Over the past decade, information fuelled by studies employing knockout and transgenic mice as well as specific inhibitors, in combination with lipidomics, has clarified when and where the different sPLA(2) isoforms are expressed, which isoforms are involved in what types of pathophysiology, and how they exhibit their specific functions. In this review, we highlight recent advances in PLA(2) research, focusing mainly on the physiological functions of sPLA(2)s and their modes of action on 'extracellular' phospholipid targets versus lipid mediator production.
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Affiliation(s)
- Makoto Murakami
- Lipid Metabolism Project, Tokyo Metropolitan Institute of Medical Science, 2-1-6 Kamikitazawa, Setagaya-ku, Tokyo 156-8506, Japan
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Henderson WR, Oslund RC, Bollinger JG, Ye X, Tien YT, Xue J, Gelb MH. Blockade of human group X secreted phospholipase A2 (GX-sPLA2)-induced airway inflammation and hyperresponsiveness in a mouse asthma model by a selective GX-sPLA2 inhibitor. J Biol Chem 2011; 286:28049-55. [PMID: 21652694 DOI: 10.1074/jbc.m111.235812] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Group X (GX) phospholipase A(2), a member of a large group of secreted phospholipases A(2) (sPLA(2)s), has recently been demonstrated to play an important in vivo role in the release of arachidonic acid and subsequent formation of eicosanoids. In a Th2 cytokine-driven mouse asthma model, deficiency of mouse GX (mGX)-sPLA(2) significantly impairs development of the asthma phenotype. In this study, we generated mGX-sPLA(2)(-/-) mice with knock-in of human GX (hGX)-sPLA(2) (i.e. hGX-sPLA(2)(+/+) knock-in mice) to understand more fully the role of GX-sPLA(2) in these allergic pulmonary responses and to assess the effect of pharmacological blockade of the GX-sPLA(2)-mediated responses. Knock-in of hGX-sPLA(2) in mGX-sPLA(2)(-/-) mice restored the allergen-induced airway infiltration by inflammatory cells, including eosinophils, goblet cell metaplasia, and hyperresponsiveness to methacholine in the mGX-sPLA(2)-deficient mice. This knock-in mouse model enabled the use of a highly potent indole-based inhibitor of hGX-sPLA(2), RO061606 (which is ineffective against mGX-sPLA(2)), to assess the potential utility of GX-sPLA(2) blockade as a therapeutic intervention in asthma. Delivery of RO061606 via mini-osmotic pumps enabled the maintenance in vivo in the mouse asthma model of plasma inhibitor concentrations near 10 μm, markedly higher than the IC(50) for inhibition of hGX-sPLA(2) in vitro. RO061606 significantly decreased allergen-induced airway inflammation, mucus hypersecretion, and hyperresponsiveness in the hGX-sPLA(2)(+/+) knock-in mouse. Thus, development of specific hGX-sPLA(2) inhibitors may provide a new pharmacological opportunity for the treatment of patients with asthma.
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Affiliation(s)
- William R Henderson
- Center for Allergy and Inflammation, Department of Medicine, University of Washington, Seattle, Washington 98195-1700, USA
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