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Veytia-Bucheli JI, Alvarado-Velázquez DA, Possani LD, González-Amaro R, Rosenstein Y. The Ca 2+ Channel Blocker Verapamil Inhibits the In Vitro Activation and Function of T Lymphocytes: A 2022 Reappraisal. Pharmaceutics 2022; 14:pharmaceutics14071478. [PMID: 35890372 PMCID: PMC9324055 DOI: 10.3390/pharmaceutics14071478] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2022] [Revised: 07/12/2022] [Accepted: 07/12/2022] [Indexed: 02/04/2023] Open
Abstract
Ca2+ channel blockers (CCBs) are commonly used to treat different cardiovascular conditions. These drugs disrupt the intracellular Ca2+ signaling network, inhibiting numerous cellular functions in different cells, including T lymphocytes. We explored the effect of the CCB verapamil on normal human peripheral blood T cell activation, proliferation, and cytokine production. Cells were activated by ligating CD3 or CD3/CD28 in the presence or absence of verapamil, and the expression of activation-induced cell surface molecules (CD25, CD40L, CD69, PD-1, and OX40), cell proliferation, and cytokine release were assessed by flow cytometry. Verapamil exerted a dose-dependent inhibitory effect on the expression of all the activation-induced cell surface molecules tested. In addition, verapamil diminished T cell proliferation induced in response to CD3/CD28 stimulation. Likewise, the production of Th1/Th17 and Th2 cytokines was also reduced by verapamil. Our data substantiate a potent in vitro suppressive effect of verapamil on T lymphocytes, a fact that might be relevant in patients receiving CCBs.
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Affiliation(s)
- José Ignacio Veytia-Bucheli
- Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad 2001, Cuernavaca 62210, Mexico; (J.I.V.-B.); (D.A.A.-V.); (L.D.P.)
- Laboratoire de Chimie Bio-Organique, Département de Chimie, Faculté des Sciences, Université de Namur, Rue de Bruxelles 615, 5000 Namur, Belgium
| | - Den Alejandro Alvarado-Velázquez
- Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad 2001, Cuernavaca 62210, Mexico; (J.I.V.-B.); (D.A.A.-V.); (L.D.P.)
- Posgrado en Ciencias, Instituto de Investigación en Ciencias Básicas y Aplicadas, Universidad Autónoma del Estado de Morelos, Av. Universidad 1001, Cuernavaca 62209, Mexico
| | - Lourival Domingos Possani
- Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad 2001, Cuernavaca 62210, Mexico; (J.I.V.-B.); (D.A.A.-V.); (L.D.P.)
| | - Roberto González-Amaro
- Centro de Investigación en Ciencias de la Salud y Biomedicina, Universidad Autónoma de San Luis Potosí, Av. Sierra Leona 550, San Luis Potosí 78210, Mexico;
| | - Yvonne Rosenstein
- Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad 2001, Cuernavaca 62210, Mexico; (J.I.V.-B.); (D.A.A.-V.); (L.D.P.)
- Correspondence: ; Tel.: +52-(777)-329-1606
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Yano E. Adverse health effects of asbestos: solving mysteries regarding asbestos carcinogenicity based on follow-up survey of a Chinese factory. Environ Health Prev Med 2018; 23:35. [PMID: 30089452 PMCID: PMC6083519 DOI: 10.1186/s12199-018-0726-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Accepted: 07/25/2018] [Indexed: 11/29/2022] Open
Abstract
The present review summarizes the results of several follow-up studies assessing an asbestos product manufacturing plant in Chongqing, China, and discusses three controversial issues related to the carcinogenicity of asbestos. The first issue is the amphibole hypothesis, which asserts that the carcinogenicity of asbestos is limited to amphiboles, such as crocidolite, but not serpentines, such as chrysotile. However, considering the possible multiple component of asbestos carcinogenicity in the presence of tobacco smoke or other carcinogens, chrysotile cannot be regarded as non-carcinogenic. Additionally, in a practical sense, it is not possible to assume "pure" chrysotile due to its ubiquitous contamination with tremolite, which is a type of amphibole. Thus, as the International Agency for Research on Cancer (IARC) assessed, all forms of asbestos including chrysotile should be regarded carcinogenic to humans (Group 1). The second issue is the chrysotile/tremolite paradox, which is a phenomenon involving predominant levels of tremolite in the lung tissues of individuals who worked in locations with negligible levels of tremolite due to the exclusive use of chrysotile. Four possible mechanisms to explain this paradox have been proposed but this phenomenon does not support the claim that amphibole is inert. The final issue discussed is the textile mystery, i.e., the higher incidence of cancer in asbestos textile plants compared to asbestos mines where the same asbestos was produced and the exposure levels were comparable. This phenomenon was first reported in North America followed by UK and then in the present observations from China. Previously, levels of fiber exposure were calculated using a universal converting coefficient to estimate the mass concentration versus fiber concentration. However, parallel measurements of fiber and mass concentrations in the workplace and exposed air indicated that there are wide variations in the fiber/mass ratio, which unjustifies the universal conversion. It is possible that contamination by airborne non-fibrous particles in mines with mass fiber conversion led to the overestimation of fiber concentrations and resulted in the textile mystery. Although the use and manufacturing of asbestos has been banned in Japan, more than 10 million tons of asbestos had been imported and the majority remains in existing buildings. Thus, efforts to control asbestos exposure should be continued.
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Affiliation(s)
- Eiji Yano
- Teikyo University Graduate School of Public Health, 2-11-1 Kaga, Itabashi-ku, Tokyo, 173-8605, Japan.
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3
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Pascolo L, Zabucchi G, Gianoncelli A, Kourousias G, Trevisan E, Pascotto E, Casarsa C, Ryan C, Lucattelli M, Lungarella G, Cavarra E, Bartalesi B, Zweyer M, Cammisuli F, Melato M, Borelli V. Synchrotron X-ray microscopy reveals early calcium and iron interaction with crocidolite fibers in the lung of exposed mice. Toxicol Lett 2016; 241:111-20. [DOI: 10.1016/j.toxlet.2015.11.016] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2015] [Revised: 11/11/2015] [Accepted: 11/13/2015] [Indexed: 01/11/2023]
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Øvrevik J, Refsnes M, Låg M, Holme JA, Schwarze PE. Activation of Proinflammatory Responses in Cells of the Airway Mucosa by Particulate Matter: Oxidant- and Non-Oxidant-Mediated Triggering Mechanisms. Biomolecules 2015; 5:1399-440. [PMID: 26147224 PMCID: PMC4598757 DOI: 10.3390/biom5031399] [Citation(s) in RCA: 144] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2015] [Revised: 06/16/2015] [Accepted: 06/16/2015] [Indexed: 12/23/2022] Open
Abstract
Inflammation is considered to play a central role in a diverse range of disease outcomes associated with exposure to various types of inhalable particulates. The initial mechanisms through which particles trigger cellular responses leading to activation of inflammatory responses are crucial to clarify in order to understand what physico-chemical characteristics govern the inflammogenic activity of particulate matter and why some particles are more harmful than others. Recent research suggests that molecular triggering mechanisms involved in activation of proinflammatory genes and onset of inflammatory reactions by particles or soluble particle components can be categorized into direct formation of reactive oxygen species (ROS) with subsequent oxidative stress, interaction with the lipid layer of cellular membranes, activation of cell surface receptors, and direct interactions with intracellular molecular targets. The present review focuses on the immediate effects and responses in cells exposed to particles and central down-stream signaling mechanisms involved in regulation of proinflammatory genes, with special emphasis on the role of oxidant and non-oxidant triggering mechanisms. Importantly, ROS act as a central second-messenger in a variety of signaling pathways. Even non-oxidant mediated triggering mechanisms are therefore also likely to activate downstream redox-regulated events.
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Affiliation(s)
- Johan Øvrevik
- Department of Air Pollution and Noise, Division of Environmental Medicine, Norwegian Institute of Public Health, P.O. Box 4404 Nydalen, N-0403 Oslo, Norway.
| | - Magne Refsnes
- Department of Air Pollution and Noise, Division of Environmental Medicine, Norwegian Institute of Public Health, P.O. Box 4404 Nydalen, N-0403 Oslo, Norway.
| | - Marit Låg
- Department of Air Pollution and Noise, Division of Environmental Medicine, Norwegian Institute of Public Health, P.O. Box 4404 Nydalen, N-0403 Oslo, Norway.
| | - Jørn A Holme
- Department of Air Pollution and Noise, Division of Environmental Medicine, Norwegian Institute of Public Health, P.O. Box 4404 Nydalen, N-0403 Oslo, Norway.
| | - Per E Schwarze
- Department of Air Pollution and Noise, Division of Environmental Medicine, Norwegian Institute of Public Health, P.O. Box 4404 Nydalen, N-0403 Oslo, Norway.
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Shannahan JH, Ghio AJ, Schladweiler MC, Richards JH, Andrews D, Gavett SH, Kodavanti UP. Transcriptional activation of inflammasome components by Libby amphibole and the role of iron. Inhal Toxicol 2011; 24:60-9. [PMID: 22168577 DOI: 10.3109/08958378.2011.633942] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The induction of the NALP3 inflammasome complex is shown to be necessary for the development of fibrosis after asbestos exposure. Libby amphibole (LA) induces lung inflammation and fibrosis, while complexation of iron (Fe) on fibers inhibits inflammation. In this study we examined the ability of LA to induce the inflammasome cascade and the role of Fe in modulating inflammasome activity. Spontaneously hypertensive rats were exposed intratracheally to either saline (300 μl), deferoxamine (Def) (1 mg), FeCl(3) (21 μg), LA (0.5 mg), Fe-loaded LA (Fe + LA), or LA + Def. Activities of oxidative stress-sensitive enzymes, expression of inflammasome-specific genes, and cytokine proteins in bronchoalveolar lavage fluid were analyzed. Lung enzymes at 4 h and 24 h post-exposure were unchanged. LA increased lung expression of genes including interleukin-1β (IL-1β), cathepsin-B, ASC, NALP3, interleukin (IL)-6 and NFκB. LA+Fe significantly reduced IL-1β and NFκB with a trend of reduction in ASC, NALP3, cathepsin-B and IL-6 expression. Def treatment did not reverse the inhibitory effect of Fe on IL-1β and ASC but reversed IL-6 expression. CCL-7, CCL-12, CXCL-3 and COX-2 were induced by LA while LA+Fe tended to reduce these responses. Phosphorylation of ERK but not MEK was increased at 4 h after LA but not LA+Fe exposure. In conclusion, components of the NALP3 inflammasome are transcriptionally activated acutely during LA-induced inflammation. The key inflammatory regulators IL-1β and NFκB were inhibited in the presence of surface-complexed Fe possibly through decreased ERK signaling upstream of the NALP3 inflammasome. The inflammasome activation by LA may contribute to fibrosis, and Fe may reduce this response and alter compensatory mechanisms in individuals exposed to LA.
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Affiliation(s)
- J H Shannahan
- Curriculum in Toxicology, UNC School of Medicine, Chapel Hill, NC, USA
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In Vitro Study of Mutagenesis Induced by Crocidolite-Exposed Alveolar Macrophages NR8383 in Cocultured Big Blue Rat2 Embryonic Fibroblasts. J Toxicol 2010; 2010:323828. [PMID: 20628587 PMCID: PMC2901601 DOI: 10.1155/2010/323828] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2009] [Revised: 03/08/2010] [Accepted: 03/18/2010] [Indexed: 11/26/2022] Open
Abstract
Asbestos-induced mutagenicity in the lung may involve reactive oxygen/nitrogen species (ROS/RNS) released by alveolar macrophages. With the aim of proposing an alternative in vitro mutagenesis test, a coculture system of rat alveolar macrophages (NR8383) and transgenic Big Blue Rat2 embryonic fibroblasts was developed and tested with a crocidolite sample. Crocidolite exposure induced no detectable increase in ROS production from NR8383, contrasting with the oxidative burst that occurred following a brief exposure (1 hour) to zymosan, a known macrophage activator. In separated cocultures, crocidolite and zymosan induced different changes in the gene expressions involved in cellular inflammation in NR8383 and Big Blue. In particular, both particles induced up-regulation of iNOS expression in Big Blue, suggesting the formation of potentially genotoxic nitrogen species. However, crocidolite exposure in separated or mixed cocultures induced no mutagenic effects whereas an increase in Big Blue mutants was detected after exposure to zymosan in mixed cocultures. NR8383 activation by crocidolite is probably insufficient to induce in vitro mutagenic events. The mutagenesis assay based on the coculture of NR8383 and Big Blue cannot be used as an alternative in vitro method to assess the mutagenic properties of asbestos fibres.
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Becher R, Bucht A, Øvrevik J, Hongslo JK, Dahlman HJ, Samuelsen JT, Schwarze PE. Involvement of NADPH oxidase and iNOS in rodent pulmonary cytokine responses to urban air and mineral particles. Inhal Toxicol 2007; 19:645-55. [PMID: 17510837 DOI: 10.1080/08958370701353528] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
We have investigated the potential of two complex mineral particles (feldspar and mylonite), quartz (Min-U-Sil), and suspended particulate matter (SRM-1648) (SPM) from urban air to induce inflammatory cytokine responses in primary rat alveolar type 2 cells and alveolar macrophages, and the involvement of cellular formation of free radicals in these responses. All particle types induced an increased release of interleukin (IL)-6 and macrophage inflammatory protein (MIP)-2 from type 2 cells. Diphenyleneiodonium chloride (DPI), a selective inhibitor of NADPH-oxidase, reduced the IL-6 and MIP-2 responses to quartz, SPM and mylonite. N-(3-[Aminomethyl] benzyl) acetamidine (1400W), a selective inhibitor of inducible nitric oxide synthase (iNOS), significantly reduced the Il-6 response to SPM and feldspar in the type 2 cells. The macrophages displayed significantly increased TNF-alpha and MIP-2 release upon exposure to quartz or SPM. Here, DPI significantly reduced the tumor necrosis factor (TNF)-alpha and MIP-2 responses to quartz, and the MIP-2 response to SPM. No significant effect of 1400 W was detected in the alveolar macrophages. The role of particle-induced cellular generation of free radicals in lung cytokine responses was further elucidated in mice that lacked either NADPH-oxidase or iNOS as well as in wild-type (wt) mice. All particles were able to elicit increased cytokine levels in the bronchoalveolar lavage (BAL) fluid of the mice, although the levels depended on particle type. The NADPH-oxidase knockout (KO) mice demonstrated a significantly lower IL-6 and MIP-2 responses to SPM compared to their respective wt mice. The iNOS KO mice displayed significantly reduced IL-6, TNF-alpha, and MIP-2 responses to SPM. The overall results indicate the involvement of cellular free-radical formation in the pulmonary cytokine responses to particles of varying composition.
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Affiliation(s)
- Rune Becher
- Division of Environmental Medicine, Section for Air Pollution Toxicology and Noise, Norwegian Institute of Public Health, Oslo, Norway.
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Tan RJ, Fattman CL, Watkins SC, Oury TD. Redistribution of pulmonary EC-SOD after exposure to asbestos. J Appl Physiol (1985) 2004; 97:2006-13. [PMID: 15298984 DOI: 10.1152/japplphysiol.00480.2004] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Inhalation of asbestos fibers leads to interstitial lung disease (asbestosis) characterized by inflammation and fibrosis. The pathogenesis of asbestosis is not fully understood, but reactive oxygen species are thought to play a central role. Extracellular superoxide dismutase (EC-SOD) is an antioxidant enzyme that protects the lung in a bleomycin-induced pulmonary fibrosis model, but its role has not been studied in asbestos-mediated disease. EC-SOD is found in high levels in the extracellular matrix of lung alveoli because of its positively charged heparin-binding domain. Proteolytic removal of this domain results in clearance of EC-SOD from the matrix of tissues. We treated wild-type C57BL/6 mice with 0.1 mg of crocidolite asbestos by intratracheal instillation and euthanized them 24 h later. Compared with saline- or titanium dioxide-treated control mice, bronchoalveolar lavage fluid (BALF) from asbestos-treated mice contained significantly higher total protein levels and increased numbers of inflammatory cells, predominantly neutrophils, indicating acute lung injury in response to asbestos. Decreased EC-SOD protein and activity were found in the lungs of asbestos-treated mice, whereas more EC-SOD was found in the BALF of these mice. The EC-SOD in the BALF was predominantly in the proteolyzed form, which lacks the heparin-binding domain. This redistribution of EC-SOD correlated with development of fibrosis 14 days after asbestos exposure. These data suggest that asbestos injury leads to enhanced proteolysis and clearance of EC-SOD from lung parenchyma into the air spaces. The depletion of EC-SOD from the extracellular matrix may increase susceptibility of the lung to oxidative stress during asbestos-mediated lung injury.
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Affiliation(s)
- Roderick J Tan
- Department of Pathology, University of Pittsburgh, Pittsburgh, PA 15261, USA
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Carter AB, Tephly LA, Venkataraman S, Oberley LW, Zhang Y, Buettner GR, Spitz DR, Hunninghake GW. High Levels of Catalase and Glutathione Peroxidase Activity Dampen H2O2Signaling in Human Alveolar Macrophages. Am J Respir Cell Mol Biol 2004; 31:43-53. [PMID: 14962975 DOI: 10.1165/rcmb.2003-0377oc] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Results are presented which support the hypothesis that adequate steady-state levels of hydrogen peroxide (H2O2) are required to overcome the effects of high catalase and glutathione peroxidase (GPx) expression for p38 mitogen-activated protein (MAP) kinase activation and tumor necrosis factor (TNF)-alpha gene expression in human alveolar macrophages stimulated with asbestos. We found significant differences in the types and amounts of reactive oxygen species generated in human blood monocytes compared with human alveolar macrophages. This difference in reactive oxygen species production is related, in part, to the differences in antioxidant enzyme expression and activity. Most importantly, catalase and GPx activities were significantly increased in alveolar macrophages compared with blood monocytes. Asbestos activated the p38 MAP kinase and induced TNF-alpha gene expression only in blood monocytes. Increasing the steady-state levels of H2O2 by using polyethylene glycol superoxide dismutase, an antioxidant that crosses the cell membrane, or aminotriazole, an irreversible inhibitor of catalase, allowed the p38 MAP kinase to be activated in alveolar macrophages. In addition, asbestos-stimulated macrophages cultured with polyethylene glycol superoxide dismutase had a significant increase in gene expression mediated by the TNF-alpha promoter. These results demonstrate that high catalase and GPx activity in human alveolar macrophages limits the effectiveness of H2O2 to act as a mediator of inflammatory gene expression.
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MESH Headings
- Adolescent
- Adult
- Amitrole/pharmacology
- Asbestos
- Catalase/metabolism
- Cells, Cultured
- Gene Expression Regulation, Enzymologic/drug effects
- Gene Expression Regulation, Enzymologic/genetics
- Glutathione Peroxidase/metabolism
- Humans
- Hydrogen Peroxide/metabolism
- Lung/enzymology
- Lung/metabolism
- Macrophages, Alveolar/drug effects
- Macrophages, Alveolar/enzymology
- Macrophages, Alveolar/metabolism
- Mitogen-Activated Protein Kinases/genetics
- Monocytes/drug effects
- Monocytes/enzymology
- Oxidative Stress/drug effects
- Oxidative Stress/physiology
- Pneumonia/enzymology
- Pneumonia/metabolism
- Promoter Regions, Genetic/drug effects
- Promoter Regions, Genetic/genetics
- RNA, Messenger/drug effects
- RNA, Messenger/metabolism
- Reactive Oxygen Species/metabolism
- Signal Transduction/drug effects
- Signal Transduction/physiology
- Superoxide Dismutase/metabolism
- Superoxide Dismutase/pharmacology
- Tumor Necrosis Factor-alpha/genetics
- Up-Regulation/drug effects
- Up-Regulation/physiology
- p38 Mitogen-Activated Protein Kinases
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Affiliation(s)
- A Brent Carter
- Department of Medicine, University of Iowa Roy J. and Lucille A Carver College of Medicine, Iowa City Veterans Administration medical Center, Iowa City, IA 52242, USA.
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Iwata T, Kohyama N, Yano E. Chemiluminescent detection of induced reactive oxygen metabolite production of human polymorphonuclear leucocytes by anthophyllite asbestos. ENVIRONMENTAL RESEARCH 2002; 88:36-40. [PMID: 11896666 DOI: 10.1006/enrs.2001.4314] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Incidences of lung cancer and pleural plaque have been reported in relation to exposure to anthophyllite asbestos. To investigate the pathogenic mechanisms of anthophyllite, chemiluminescence (CL) detection of reactive oxygen metabolite (ROM) generation of human polymorphonuclear leucocytes (PMN) stimulated by anthophyllite asbestos was determined and compared with that of other asbestos and mineral fiber samples. When anthophyllite fiber sample was mixed with the luminol-primed PMN, high levels of CL which exhibited a specific time course characterized by two separate peaks were induced. The CL induced by anthophyllite sample was greater than that induced by chrysotile, crocidolite, and amosite asbestos. We further investigated the two peaks of CL using specific inhibitors of signal transduction mechanisms. The two peaks of CL by anthophyllite sample were different in sensitivity to cytochalasin B and genistein; the former relates to the cytoskeleton-dependent mechanism and the latter has been shown to inhibit tyrosine kinase, which resides in the pathway to cause PMN activation. The strong ROM reaction of PMN by anthophyllite suggests that the surface characteristics of the fiber may participate in the pathogenic mechanisms of anthophyllite asbestos.
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Affiliation(s)
- Toyoto Iwata
- Department of Public Health, Teikyo University School of Medicine, 11-1, Kaga 2-chome, Itabashi-ku, Tokyo 173-8605, Japan
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Siddiqui RA, Burtschi DJ, Kovacs R. Phosphatidic acid induces calcium influx in neutrophils via verapamil-sensitive calcium channels. J Cell Biochem 2000; 78:297-304. [PMID: 10842323 DOI: 10.1002/(sici)1097-4644(20000801)78:2<297::aid-jcb11>3.0.co;2-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Phosphatidic acid (PA) induces a biphasic Ca(2+) mobilization response in human neutrophils. The initial increase is due to the mobilization of Ca(2+) from intracellular stores, whereas the secondary increase is due to the influx of Ca(2+) from extracellular sources. The present investigation characterizes PA-induced Ca(2+) influx in neutrophils. Depolarization of neutrophils by 50 mM KCl enhanced PA-induced Ca(2+) influx, whereas verapamil, a Ca(2+) channel blocker, attenuated this response in a dose-dependent manner. These observations suggest that PA-induced Ca(2+) influx is mediated via verapamil-sensitive Ca(2+) channels. Stimulation of neutrophils with exogenous PA results in accumulation of endogenously generated PA with a time course similar to the effects of exogenous PA on Ca(2+) influx. Ethanol inhibited the accumulation of endogenous PA and calcium mobilization, indicating that activation of membrane phospholipase D plays a role in PA-mediated Ca(2+) influx. The results of this study suggest that exogenously added PA stimulates the generation of intracellular PA, which then mediates Ca(2+) influx through verapamil-sensitive Ca(2+) channels.
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Affiliation(s)
- R A Siddiqui
- Cellular Biochemistry Laboratory, Methodist Research Institute, Indianapolis, Indiana.
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12
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Affiliation(s)
- D W Kamp
- Department of Medicine, Pulmonary & Critical Care Medicine, Veterans Affairs Chicago Health Care System (Lakeside Division) and Northwestern University Medical School, Chicago, Illinois 60611, USA
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