1
|
Han X, Guo B, Wang L, Chen K, Zhou H, Huang S, Xu H, Pan X, Chen J, Gao X, Wang Z, Yang L, Laba C, Meng Q, Guo Y, Chen G, Hong F, Zhao X. The mediation role of blood lipids on the path from air pollution exposure to MAFLD: A longitudinal cohort study. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 904:166347. [PMID: 37591384 DOI: 10.1016/j.scitotenv.2023.166347] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Revised: 08/12/2023] [Accepted: 08/14/2023] [Indexed: 08/19/2023]
Abstract
BACKGROUND & AIMS Recent cross-sectional studies found that exposure to ambient air pollution (AP) was associated with an increased risk of metabolic dysfunction-associated fatty liver disease (MAFLD). The alternation of blood lipids may explain the association, but epidemiological evidence is lacking. We aimed to examine whether and to what extent the association between long-term exposure to AP and incident MAFLD is mediated by blood lipids and dyslipidemia in a prospective cohort. METHODS We included 6350 participants from the China Multi-Ethnic Cohort (CMEC, baseline 2018-2019, follow-up 2020-2021). Three-year average (2016-2018) of AP (PM1, PM2.5, PM10, NO2), blood lipids (TC, LDL-C, HDL-C, TG with their combinations) and incident MAFLD for each individual were assessed chronologically. Linear and logistic regression was used to assess the associations among AP, blood lipids, and MAFLD, and the potential mediation effects of blood lipids were evaluated using causal mediation analysis. RESULTS A total of 744 participants were newly diagnosed with MAFLD at follow-up. The odds ratios of MAFLD associated with a 10 μm increase in PM1, PM2.5, and NO2 were 1.35 (95 % CI: 1.14, 1.58), 1.34 (1.10, 1.65) and 1.28 (1.14, 1.44), respectively. Blood lipids are important mediators between AP and incident MAFLD. LDL-C (Proportion Mediated: 6.9 %), non-HDL (13.4 %), HDL-C (20.7 %), LDL/HDL (30.1 %), and dyslipidemia (6.5 %) significantly mediated the association between PM2.5 and MAFLD. For PM1, the indirect effects were similar to those for PM2.5, with a larger value for the direct effect, and the mediation proportion by blood lipids was less for NO2. CONCLUSION Blood lipids are important mediators between AP and MAFLD, and can explain 5 %-30 % of the association between AP and incident MAFLD, particularly cholesterol-related variables, indicating that AP could lead to MAFLD through the alternation of blood lipids. These findings provided mechanical evidence of AP leading to MAFLD in epidemiological studies.
Collapse
Affiliation(s)
- Xinyu Han
- West China School of Public Health and West China Fourth Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Bing Guo
- West China School of Public Health and West China Fourth Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Lele Wang
- West China School of Public Health and West China Fourth Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Kejun Chen
- West China School of Public Health and West China Fourth Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Hanwen Zhou
- West China School of Public Health and West China Fourth Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Shourui Huang
- West China School of Public Health and West China Fourth Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Huan Xu
- West China School of Public Health and West China Fourth Hospital, Sichuan University, Chengdu, Sichuan, China; Institute for Disaster Management and Reconstruction, Sichuan University-The Hongkong Polytechnic University, Chengdu, Sichuan, China
| | - Xianmou Pan
- West China School of Public Health and West China Fourth Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Jinyao Chen
- West China School of Public Health and West China Fourth Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Xufang Gao
- Chengdu Center for Disease Control and Prevention, Chengdu, Sichuan, China
| | - Zhenghong Wang
- Chongqing Municipal Center for Disease Control and Prevention, Chongqing, China
| | - La Yang
- Tibet University, Lhasa, Tibet, China
| | - Ciren Laba
- Tibet Center for Disease Control and Prevention CN, Lhasa, Tibet, China
| | - Qiong Meng
- Department of Epidemiology and Health Statistics, School of public Health, Kunming Medical University, Kunming, Yunnan, China
| | - Yuming Guo
- Department of Epidemiology and Preventive Medicine, School of Public Health and Preventive Medicine, Monash University, Melbourne, VIC 3004, Australia
| | - Gongbo Chen
- Climate, Air Quality Research Unit, School of Public Health and Preventive Medicine, Monash University, Melbourne, Australia.
| | - Feng Hong
- School of Public Health, the key Laboratory of Environmental Pollution Monitoring and Disease Control, Ministry of Education, Guizhou Medical University, Guiyang, China.
| | - Xing Zhao
- West China School of Public Health and West China Fourth Hospital, Sichuan University, Chengdu, Sichuan, China.
| |
Collapse
|
2
|
de F C Lichtenfels AJ, van der Plaat DA, de Jong K, van Diemen CC, Postma DS, Nedeljkovic I, van Duijn CM, Amin N, la Bastide-van Gemert S, de Vries M, Ward-Caviness CK, Wolf K, Waldenberger M, Peters A, Stolk RP, Brunekreef B, Boezen HM, Vonk JM. Long-term Air Pollution Exposure, Genome-wide DNA Methylation and Lung Function in the LifeLines Cohort Study. ENVIRONMENTAL HEALTH PERSPECTIVES 2018; 126:027004. [PMID: 29410382 PMCID: PMC6047358 DOI: 10.1289/ehp2045] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Revised: 12/13/2017] [Accepted: 12/13/2017] [Indexed: 05/17/2023]
Abstract
BACKGROUND Long-term air pollution exposure is negatively associated with lung function, yet the mechanisms underlying this association are not fully clear. Differential DNA methylation may explain this association. OBJECTIVES Our main aim was to study the association between long-term air pollution exposure and DNA methylation. METHODS We performed a genome-wide methylation study using robust linear regression models in 1,017 subjects from the LifeLines cohort study to analyze the association between exposure to nitrogen dioxide (NO2) and particulate matter (PM2.5, fine particulate matter with aerodynamic diameter ≤2.5 μm; PM10, particulate matter with aerodynamic diameter ≤10 μm) and PM2.5absorbance, indicator of elemental carbon content (estimated with land-use-regression models) with DNA methylation in whole blood (Illumina® HumanMethylation450K BeadChip). Replication of the top hits was attempted in two independent samples from the population-based Cooperative Health Research in the Region of Augsburg studies (KORA). RESULTS Depending on the p-value threshold used, we found significant associations between NO2 exposure and DNA methylation for seven CpG sites (Bonferroni corrected threshold p<1.19×10-7) or for 4,980 CpG sites (False Discovery Rate<0.05). The top associated CpG site was annotated to the PSMB9 gene (i.e., cg04908668). None of the seven Bonferroni significant CpG-sites were significantly replicated in the two KORA-cohorts. No associations were found for PM exposure. CONCLUSIONS Long-term NO2 exposure was genome-wide significantly associated with DNA methylation in the identification cohort but not in the replication cohort. Future studies are needed to further elucidate the potential mechanisms underlying NO2-exposure-related respiratory disease. https://doi.org/10.1289/EHP2045.
Collapse
Affiliation(s)
- Ana Julia de F C Lichtenfels
- Department of Epidemiology, University of Groningen, University Medical Center Groningen, Groningen, Netherlands
- Groningen Research Institute for Asthma and COPD (GRIAC), University of Groningen, University Medical Center Groningen , Groningen, Netherlands
| | - Diana A van der Plaat
- Department of Epidemiology, University of Groningen, University Medical Center Groningen, Groningen, Netherlands
- Groningen Research Institute for Asthma and COPD (GRIAC), University of Groningen, University Medical Center Groningen , Groningen, Netherlands
| | - Kim de Jong
- Department of Epidemiology, University of Groningen, University Medical Center Groningen, Groningen, Netherlands
- Groningen Research Institute for Asthma and COPD (GRIAC), University of Groningen, University Medical Center Groningen , Groningen, Netherlands
| | - Cleo C van Diemen
- Department of Genetics, University of Groningen, University Medical Center Groningen, Groningen, Netherlands
| | - Dirkje S Postma
- Groningen Research Institute for Asthma and COPD (GRIAC), University of Groningen, University Medical Center Groningen , Groningen, Netherlands
- Department of Pulmonary Diseases, University of Groningen, University Medical Center Groningen, Groningen , Netherlands
| | - Ivana Nedeljkovic
- Department of Epidemiology, Erasmus Medical Center, Rotterdam, Netherlands
| | | | - Najaf Amin
- Department of Epidemiology, Erasmus Medical Center, Rotterdam, Netherlands
| | - Sacha la Bastide-van Gemert
- Department of Epidemiology, University of Groningen, University Medical Center Groningen, Groningen, Netherlands
| | - Maaike de Vries
- Department of Epidemiology, University of Groningen, University Medical Center Groningen, Groningen, Netherlands
- Groningen Research Institute for Asthma and COPD (GRIAC), University of Groningen, University Medical Center Groningen , Groningen, Netherlands
| | - Cavin K Ward-Caviness
- Institute of Epidemiology II, Helmholtz Zentrum München , Neuherberg, Germany
- Environmental Public Health Division, U.S. Environmental Protection Agency , Chapel Hill, North Carolina, USA
| | - Kathrin Wolf
- Institute of Epidemiology II, Helmholtz Zentrum München , Neuherberg, Germany
| | | | - Annette Peters
- Institute of Epidemiology II, Helmholtz Zentrum München , Neuherberg, Germany
| | - Ronald P Stolk
- Department of Epidemiology, University of Groningen, University Medical Center Groningen, Groningen, Netherlands
| | - Bert Brunekreef
- Institute for Risk Assessment Sciences , Utrecht University, Utrecht, Netherlands
- Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht , Netherlands
| | - H Marike Boezen
- Department of Epidemiology, University of Groningen, University Medical Center Groningen, Groningen, Netherlands
- Groningen Research Institute for Asthma and COPD (GRIAC), University of Groningen, University Medical Center Groningen , Groningen, Netherlands
| | - Judith M Vonk
- Department of Epidemiology, University of Groningen, University Medical Center Groningen, Groningen, Netherlands
- Groningen Research Institute for Asthma and COPD (GRIAC), University of Groningen, University Medical Center Groningen , Groningen, Netherlands
| |
Collapse
|
3
|
Li YD, Patel JM, Zhang J, Block ER. Overexpression of plasma membrane annexin II in NO2-exposed pulmonary artery endothelial cells. Free Radic Biol Med 1997; 23:120-6. [PMID: 9165304 DOI: 10.1016/s0891-5849(96)00627-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Because exposure to nitrogen dioxide (NO2) alters plasma membrane structure and function in pulmonary artery endothelial cells (PAEC), we examined whether NO2 exposure is associated with upregulation of plasma membrane-specific proteins in PAEC. Exposure to 5 ppm NO2 for 24 h had no significant effect on total protein synthesis. However, two-dimensional gel electrophoresis of isolated plasma membranes from [35S]-methionine pulse-labeled PAEC exposed to NO2 for 24 h demonstrated 3- to 9-fold increases in the synthesis of several proteins with molecular masses of 36, 39, and 40 kDa compared with controls. N-terminal amino acid sequencing and immunodetection analysis identified the 36kDa plasma membrane protein as annexin II (lipocortin II). Northern blotting analysis demonstrated that the mRNA expression for annexin II in NO2-exposed cells was also increased. These results suggest that exposure to NO2 results in induction of plasma membrane annexin II, an important multifunctional calcium- and phospholipid-binding protein in PAEC.
Collapse
Affiliation(s)
- Y D Li
- Division of Pulmonary Medicine, University of Florida College of Medicine, Gainesville, USA
| | | | | | | |
Collapse
|
4
|
Nagasaki T, Gundersen GG. Depletion of lysophosphatidic acid triggers a loss of oriented detyrosinated microtubules in motile fibroblasts. J Cell Sci 1996; 109 ( Pt 10):2461-9. [PMID: 8923207 DOI: 10.1242/jcs.109.10.2461] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
We reported earlier that isolated plasma membranes trigger a number of responses comprising contact inhibition of motility, including loss of oriented detyrosinated microtubules (Glu MTs) from the lamella of motile fibroblasts. In this study, we show that the membranes trigger this loss of Glu MTs, not by binding to cells, but by removing an essential component from the medium necessary to maintain oriented Glu MTs. Preincubation of membranes with medium containing serum followed by removal of the membranes by sedimentation rendered the membrane-treated medium capable of triggering the loss of oriented Glu MTs. Membrane activity was inhibited by high concentrations of serum and removal of serum from medium triggered the loss of oriented Glu MTs similar to that triggered by membranes. These results suggest that the membranes trigger the loss of Glu MTs by inactivating factors in serum that are required for the maintenance of oriented Glu MTs. By fractionating serum, we have identified lysophosphatidic acid (LPA) as the principal serum factor that is responsible for supporting oriented Glu MTs. The activity of LPA to maintain oriented Glu MTs upon serum withdrawal was half maximal at 100 nM and no activity was observed with structurally related phospholipids. Serum LPA levels were sufficient to account for the ability of serum to support oriented Glu MTs. Enzymatic degradation of serum LPA strongly reduced the ability of serum to support oriented Glu MTs. That membranes degrade LPA was shown by the ability of membranes to block LPA's ability to maintain oriented Glu MTs, and by direct measurement of the loss of radiolabeled LPA after incubation with membranes in vitro. These results show that isolated plasma membranes trigger the loss of Glu MTs from the lamella of motile cells by degrading serum LPA. Coupled with earlier results showing that membranes trigger a number of contact inhibition responses, our data suggest a new model for contact inhibition of motility in which local degradation of LPA and/or interference with LPA-stimulated signalling pathways initiates a contact inhibition response in colliding cells.
Collapse
Affiliation(s)
- T Nagasaki
- Department of Anatomy and Cell Biology, Columbia University, College of Physicians and Surgeons, New York, NY, USA
| | | |
Collapse
|
5
|
Li YD, Patel JM, Block ER. NO2-induced expression of specific protein kinase C isoforms and generation of phosphatidylcholine-derived diacylglycerol in cultured pulmonary artery endothelial cells. FEBS Lett 1996; 389:131-5. [PMID: 8766815 DOI: 10.1016/0014-5793(96)00550-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The present study examines whether nitrogen dioxide (NO2)-induced activation of protein kinase C (PKC) is associated with increased expression of specific PKC isoforms and/or with enhanced generation of phosphatidylcholine(PC)-derived diacylglycerol (DAG) in pulmonary artery endothelial cells (PAEC). Western blot analysis revealed that exposure to 5 ppm NO2 resulted in increased expression of PKC alpha and epsilon isoforms in both cytosol and membrane fractions in a time-dependent fashion compared with controls. A time-dependent elevated expression of PKC isoform beta was observed in the cytosol fraction only of N02-exposed cells. PKC isoform gamma was not detectable in either the cytosolic or membrane fractions from control or N02-exposed cells. Scatchard analysis of [3h]phorbol 12,13-dibutyrate (PDBu) binding showed that exposure to N02 for 24 h increased the maximal number of binding sites (Bmax) from 15.2 +/- 2.3 pmol/mg (control) to 42.3 +/- 5.3 pmol/mg (p < 0.01, n = 4) (NO2-exposed). Exposure to NO2 significantly increased PC specific-phospholipase C and phospholipase D activities in the plasma membrane of PAEC (p < 0.05 and p < 0.001, respectively). When [3H]-myristic acid-labeled cells were exposed to NO2, significantly increased radioactivity was associated with cellular DAG. These results show for the first time that exposure of PAEC to NO2 results in elevated expression of specific PKC isoforms and in enhanced generation of cellular DAG, and the latter appears to arise largely from the hydrolysis of plasma membrane PC.
Collapse
Affiliation(s)
- Y D Li
- Division of Pulmonary Medicine, University of Florida College of Medicine, Gainesville, 32608-1197, USA
| | | | | |
Collapse
|
6
|
Li YD, Patel JM, Block ER. Nitrogen dioxide-induced expression of a 78 kDa protein in pulmonary artery endothelial cells. Free Radic Biol Med 1996; 21:163-71. [PMID: 8818631 DOI: 10.1016/0891-5849(96)00024-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Exposure to nitrogen dioxide (NO2) activates signal transduction in cultured pulmonary artery endothelial cells (PAEC). We examined whether NO2-induced activation of signal transduction results in increased expression of proteins in PAEC. Exposure to 5 ppm NO2 for 4, 12, and 24 h had no significant effect on total protein synthesis. However, two-dimensional gel electrophoresis of [35S]-methionine-labeled PAEC exposed to NO2 for 24 h, but not 4 and 12 h, demonstrated increased synthesis of several proteins including a two- to five-fold increase of some proteins with molecular masses of 47, 64, 78, and 105 kDa compared to controls. N-terminal amino acid sequencing and immunodetection analysis identified the 78 kDa protein as 78 kDa glucose-regulated protein (GRP-78). Induction of GRP-78 by NO2 exposure was regulated at the transcriptional level, and the induction required de novo protein synthesis. Exposure to NO2 for 24 h also significantly (p < .05) decreased glycosylation of proteins in PAEC. Exposure of cell monolayers to tunicamycin, an inhibitor of protein glycosylation, mimicked the effect of NO2 exposure on expression of GRP-78. Increased expression of GRP-78 was also detected when cell monolayers were exposed to the calcium ionophore A 23187, to 2-deoxyglucose, or to glucose-free medium, which are also known to cause perturbations in protein glycosylation. These results demonstrate that exposure to NO2 increases expression of a number of proteins including GRP-78 in PAEC. Increased expression of GRP-78 in NO2-exposed cells appears to be associated with inhibition of glycosylation or through coordinated alterations in metabolic events that lead to inhibition of protein glycosylation.
Collapse
Affiliation(s)
- Y D Li
- Division of Pulmonary Medicine, University of Florida College of Medicine, Gainesville, USA
| | | | | |
Collapse
|
7
|
Knight M, Sekharam M, Patel J. The effect of nitrogen dioxide exposure on the release of surfactant isolated from neonatal rabbit type II pneumocytes in culture. JOURNAL OF BIOCHEMICAL TOXICOLOGY 1995; 10:309-13. [PMID: 8934633 DOI: 10.1002/jbt.2570100605] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Nitrogen dioxide (NO2) is a well-known environmental air toxin, produced from a variety of sources, including cigarette smoke. Because of the growing knowledge of the harmful effects of passive smoking on children, we decided to study the effect of NO2 exposure on the release of surfactant from isolated neonatal type II pulmonary epithelial cells. After isolation from 1 to 4 day old rabbits, type II epithelial cells were allowed to adhere for 18 hours, washed, media changed, and were exposed to either 5% CO2 in room air or NO2, 5 ppm, for 2 hours (all results mean +/- sd; comparisons, paired t-test). There was no difference in cell number or viability prior to exposure. Cells exposed to NO2 had an increase in LDH release [LDH activity in media/(LDH in media+cells) x 100], air 12.6 +/- 2.2%, NO2 21.7 +/- 3.7%, (p < 0.05). NO2-exposed cells also had an increase in total phospholipid (microgram/cell culture dish) in media compared to air exposed, air 170.13 +/- 7.54, NO2 195.15 +/- 11.2, (p < 0.05). 3H-choline incorporation as a precursor to disaturated phosphatidylcholine (DSPC) was also conducted during exposure to either air or NO2. Incorporation of 3H-choline into surfactant lipid was increased in media from cells after NO2 exposure compared to air, 58.23 +/- 15.16 air, 76.81 +/- 19.86 NO2 (cpm/microgram protein; p < 0.05). These results show that 2 hours of 5 ppm NO2 exposure is associated with an increase in release of surfactant from neonatal type II cells in culture.
Collapse
Affiliation(s)
- M Knight
- Department of Pediatrics, University of Florida, Gainesville 32610, USA
| | | | | |
Collapse
|
8
|
Tu B, Wallin A, Moldéus P, Cotgreave IA. Cytotoxicity of NO2 gas to cultured human and murine cells in an inverted monolayer exposure system. Toxicology 1995; 96:7-18. [PMID: 7863513 DOI: 10.1016/0300-483x(94)02909-e] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
We report the development of an optimised exposure system for the exposure of inverted cell cultures to NO2, which presents several advantages over conventional, right-side-up exposure systems. Firstly, the cells may be directly exposed to NO2 in the gas phase for up to 1 h, without the interposition of an aqueous layer. Secondly, the chamber system allows simple and precise control of the gas concentration during the exposure. Finally, the system allows the simultaneous exposure of large numbers of cells under sterile conditions, facilitating further culture of the cells after the exposure period. We report the application of this system to a comparative study of the toxicity of NO2 in three different cell types involved in the circuit of the inflammatory response, the IC-21 murine macrophage line, the A-549 human pulmonary type II-like epithelial cell line and human umbilical vein endothelial cells. As little as 2 ppm NO2 for 20 min reduced colony-forming efficiency of HUVE cells and A-549 cells and A-549 cells to 35% and 78% of their air controls, respectively. Exposure to 5 ppm NO2 for 1 h increased lactate dehydrogenase release of HUVE cells, IC-21 macrophages and A-549 cells from 7.9% to 21.6%, 5.7% to 10.9% and 2.0% to 3.4%, respectively, whilst 10 ppm NO2 for 1 h lowered cellular glutathione in HUVE cells, IC-21 cells and A-549 cells from 35.2 nmol/mg to 23.3 nmol/mg, from 45.0 nmol/mg to 31.0 nmol/mg and from 86.4 nmol/mg to 69.2 nmol/mg, respectively. Of the cell types tested it was shown that HUVE cells and IC-21 cells were equally sensitive to the toxicity of NO2, whilst A-549 cells displayed considerable resistance, perhaps due to the considerably higher levels of glutathione in this cell line. Further, a comparison of the sensitivity of HUVE cells to NO2, using several modes of exposure (inverted and right-side-up (either rocked or static)) and the assay of lactate dehydrogenase and [3H]deoxyglucose release, revealed that the present inverted exposure technique potentiated the acute cytotoxicity of the gas.
Collapse
Affiliation(s)
- B Tu
- Division of Toxicology, Institute of Environmental Medicine, Stockholm, Sweden
| | | | | | | |
Collapse
|
9
|
Patel JM, Abeles AJ, Block ER. Effect of phospholipid acyl chain modulation on vitamin E incorporation into pulmonary artery endothelial cell membranes. J Cell Physiol 1993; 155:394-8. [PMID: 8482731 DOI: 10.1002/jcp.1041550221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Incorporation of vitamin E (alpha-tocopherol) was measured in total membranes of pulmonary artery endothelial cells (PAEC) following treatment with eight synthetic phosphatidylethanolamines (PE) (Palmitoyloleoyl, 16:0-18:1 PE1; distearoyl, 18:0-18:0 PE2; dioleoyl, 18:1-18:1 PE3; stearoyl- linoleoyl, 18:0-18:2 PE4; dilinoleoyl, 18:2-18:2 PE5; stearoyl-arachidonyl, 18:0-20:4 PE6; diarachidonyl, 20:4-20:4 PE7; and stearoyl-docosahexenoyl, 18:0-22:6 PE8). Endogenous PE content of native membranes was 0.88 +/- 0.01 nmol/mg protein. Incorporation of PE irrespective of fatty acid content significantly (P < 0.02) increased the PE content of total membranes. Vitamin E incorporation in control membranes was 63 +/- 9 nmol/mg protein. Incorporation of vitamin E in PE1- to PE7-treated cells were significantly (P < 0.05) increased compared to controls and were comparable to each other. Vitamin E incorporation into PE8-treated cells was threefold greater (P < 0.001) than controls and twofold greater (P < 0.001) than PE1- to PE7-treated cells. Increased PE content results in increased vitamin E incorporation into PAEC membranes irrespective of the fatty acids present on the acyl chain, and maximal incorporation of vitamin E in PE8-treated cells may relate to the increased carbon chain length rather than to the degree of unsaturation at the sn2 position.
Collapse
Affiliation(s)
- J M Patel
- Medical Research Service, Department of Veterans Affairs Medical Center, Gainesville, Florida 32608-1197
| | | | | |
Collapse
|
10
|
Bittrich H, Mátzig AK, Kráker I, Appel KE. NO2-induced DNA single strand breaks are inhibited by antioxidative vitamins in V79 cells. Chem Biol Interact 1993; 86:199-211. [PMID: 8485784 DOI: 10.1016/0009-2797(93)90098-j] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Recently, we were able to show that nitrogen dioxide (NO2), a strong oxidant, induced DNA single strand breaks (SSBs) in V79 cells. Possibly, special scavengers, e.g. antioxidative vitamins, may protect cells from NO2-induced damage. Therefore, the effect of various tocopherols, beta-carotene, retinol, and ascorbic acid on NO2-induced SSBs in V79 cells was investigated. Cells were preincubated with vitamins and treated for 10 min with 200 ppm NO2. The rate of SSBs was measured by the alkaline elution assay, the amount of DNA by a fluorimetric assay. Micromolar concentrations of d-gamma-tocopherol inhibited the rate of NO2-induced SSBs by 40%, beta-carotene and ascorbic acid by 25%. None of these vitamins had any effects on DNA or the viability of cells. When incubating the cells with retinol in a medium with pH 8.5, this vitamin inhibited NO2-induced SSBs, reducing them by 35%. However, in high concentrations, retinol itself induced SSBs and influenced cell viability. The results are discussed with regard to many toxic effects of NO2.
Collapse
Affiliation(s)
- H Bittrich
- Max von Pettenkofer-Institute, Federal Health Office, Berlin, Germany
| | | | | | | |
Collapse
|
11
|
Patel JM, Sekharam KM, Block ER. Oxidant and angiotensin II-induced subcellular translocation of protein kinase C in pulmonary artery endothelial cells. JOURNAL OF BIOCHEMICAL TOXICOLOGY 1992; 7:117-23. [PMID: 1404242 DOI: 10.1002/jbt.2570070209] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
We recently reported that nitrogen dioxide (NO2), an environmental oxidant, alters the dynamics of the plasma membrane lipid bilayer structure, resulting in increased phosphatidylserine content and angiotensin II (Ang II) receptor binding. Angiotensin II is known to elicit receptor-mediated stimulation of diacylglycerol (DAG) production in pulmonary artery endothelial cells. Because protein kinase C (PKC) is a phosphatidylserine-dependent enzyme and is activated by DAG, we examined whether NO2 resulted in activation and/or translocation of PKC from predominantly cytosolic to membrane fractions of these cells. We also evaluated whether NO2 exposure resulted in increased production of DAG in pulmonary artery endothelial cells. Exposure to 5 ppm NO2 for 1-24 hr resulted in significant increases in PKC activity in the cytosolic and membrane fractions (p less than 0.05 for both fractions) compared to activities in control fractions. Exposure to Ang II resulted in translocation of PKC activity from cytosol to membrane fractions of both control and NO2-exposed cells. This translocation of PKC from cytosolic to membrane fraction was prevented by the specific receptor antagonist [Sar1 Ile8] Ang II. Exposure of 5 ppm NO2 for 1-24 hr provoked rapid increases in [3H]glycerol labeling of DAG in pulmonary artery endothelial cells. These results demonstrate that exposure to NO2 increases the production of second messenger DAG and activates PKC in both the cytosolic and membrane fractions, whereas Ang II stimulates the redistribution of PKC from cytosolic to membrane fractions of pulmonary artery endothelial cells.
Collapse
Affiliation(s)
- J M Patel
- Division of Pulmonary Medicine, University of Florida College of Medicine, Gainesville 32610-0225
| | | | | |
Collapse
|