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Fine ambient particles induce oxidative stress and metal binding genes in human alveolar macrophages.

ABSTRACT: Exposure to pollutant particles increased respiratory morbidity and mortality. The alveolar macrophages (AMs) are one cell type in the lung directly exposed to particles. Upon contact with particles, AMs are activated and produce reactive oxygen species, but the scope of this oxidative stress response remains poorly defined. In this study, we determined the gene expression profile in human AMs exposed to particles, and sought to characterize the global response of pro- and antioxidant genes. We exposed AMs obtained by bronchoscopy from normal individuals to Chapel Hill particulate matter of 2.5-microm diameter or smaller (PM(2.5); 1 microg/ml) or vehicle for 4 hours (n = 6 independent samples). mRNAs were extracted, amplified, and hybridized to Agilent human 1A microarray. Significant genes were identified by significance analysis of microarrays (false discovery rate, 10%; P < or = 0.05) and mapped with Gene Ontology in the Database for Annotation, Visualization, and Integrated Discovery. We found 34 and 41 up- and down-regulated genes, respectively; 22 genes (approximately 30%) were involved in metal binding, and 11 were linked to oxidative stress, including up-regulation of five metallothionein (MT)-1 isoforms. Exogenous MT1 attenuated PM(2.5)-induced H2O2 release. PM(2.5) premixed with MT1 stimulated less H2O2 release. Knockdown of MT1F gene increased PM(2.5)-induced H2O2 release. PM(2.5) at 1 microg/ml did not increase H2O2 release. Mount St. Helens PM(2.5) and acid-extracted Chapel Hill PM(2.5), both poor in metals, did not induce MT1F or H2O2 release. Our results show that PM(2.5) induced a gene expression profile prevalent with genes related to metal binding and oxidative stress in human AMs, independent of oxidative stress. Metals associated with PM may play an important role in particle-induced gene changes.

SUBMITTER: Huang YC

PROVIDER: S-EPMC2778161 | biostudies-literature | 2009 Nov

REPOSITORIES: biostudies-literature

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Fine ambient particles induce oxidative stress and metal binding genes in human alveolar macrophages.

Huang Yuh-Chin T YC Li Zhuowei Z Carter Jacqueline D JD Soukup Joleen M JM Schwartz David A DA Yang Ivana V IV

American journal of respiratory cell and molecular biology 20090227 5

Exposure to pollutant particles increased respiratory morbidity and mortality. The alveolar macrophages (AMs) are one cell type in the lung directly exposed to particles. Upon contact with particles, AMs are activated and produce reactive oxygen species, but the scope of this oxidative stress response remains poorly defined. In this study, we determined the gene expression profile in human AMs exposed to particles, and sought to characterize the global response of pro- and antioxidant genes. We ...[more]

PMID: 19251948

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Project description:Exposure to particulate matter (PM) is consistently associated with increased morbidity and mortality attributable in part to respiratory illnesses. The alveolar macrophage (AM) is one of the cell types in the lung constantly exposed to and activated by ambient pollutants. Upon contact with environmental particulate pollutants, AM produces reactive oxygen species (ROS) and antioxidant enzymes, but the scope of this oxidative stress response induced by PM remains poorly defined. In this study, we used microarray analysis to determine the gene expression profile in human alveolar macrophages upon exposure to PM and sought to gain more insight into the global response of pro- and anti-oxidant enzymes to PM exposure. Human AM were obtained by bronchoscopy from normal individuals. They were then incubated with Chapel Hill PM2.5 (1 ïg/ml) or vehicle for 4 hours (n = 6 independent samples each). mRNAs were extracted, amplified and hybridized to Agilent Human 1A microarray. Differentially expressed genes were identified by Statistical Analysis for Microarrays (SAM) with a FDR of 10% and a P â¤ 0.05. Significant genes were also mapped with Gene Ontology (GO) based on their molecular function. We found 34 and 41 up- and down-regulated genes respectively. Of these, 22 genes (~30%) were involved in metal binding and 14 genes were linked to oxidative stress, including 5 metallothionein-1 (MT1) isoform genes. In lung cells, addition of MT-1F in the medium attenuated PM2.5-induced H2O2 production while knockdown of MT1F gene expression increased H2O2 and IL-6 release induced by PM2.5. Our microarray experiments provided a global view of gene expression after in vitro PM2.5 exposure in human AM. The expression profile was most notable for differential expression of genes related to metal binding and oxidative stress, especially upregulation of MT1 isoform genes. Our findings suggest that metals associated with PM, e.g., zinc, copper, and arsenic, induce MT-1 and may be the primary mediators for PM-induced oxidative stress. Keywords: in vitro exposure, PM2.5 particle treatment, human alveolar macrophages Total RNA was isolated from alveolar macrophages from 6 subjects were treated in vitro with PM2.5 particles or vehicle control for 4 hrs. All particle-treated samples were co-hybridized with the common reference sample (pool of all 6 vehicle-treated samples) twice with Cy3 and Cy5 dyes flipped (12 hybridizations). Three samples were also co-hybridized with its own individual control (vehicle-treatment for the same subject) with Cy3 and Cy5 dyes flipped (6 additional hybridizations).

Project description:Exposure to particulate matter (PM) is consistently associated with increased morbidity and mortality attributable in part to respiratory illnesses. The alveolar macrophage (AM) is one of the cell types in the lung constantly exposed to and activated by ambient pollutants. Upon contact with environmental particulate pollutants, AM produces reactive oxygen species (ROS) and antioxidant enzymes, but the scope of this oxidative stress response induced by PM remains poorly defined. In this study, we used microarray analysis to determine the gene expression profile in human alveolar macrophages upon exposure to PM and sought to gain more insight into the global response of pro- and anti-oxidant enzymes to PM exposure. Human AM were obtained by bronchoscopy from normal individuals. They were then incubated with Chapel Hill PM2.5 (1 ug/ml) or vehicle for 4 hours (n = 6 independent samples each). mRNAs were extracted, amplified and hybridized to Agilent Human 1A microarray. Differentially expressed genes were identified by Statistical Analysis for Microarrays (SAM) with a FDR of 10% and a P ≤ 0.05. Significant genes were also mapped with Gene Ontology (GO) based on their molecular function. We found 34 and 41 up- and down-regulated genes respectively. Of these, 22 genes (~30%) were involved in metal binding and 14 genes were linked to oxidative stress, including 5 metallothionein-1 (MT1) isoform genes. In lung cells, addition of MT-1F in the medium attenuated PM2.5-induced H2O2 production while knockdown of MT1F gene expression increased H2O2 and IL-6 release induced by PM2.5. Our microarray experiments provided a global view of gene expression after in vitro PM2.5 exposure in human AM. The expression profile was most notable for differential expression of genes related to metal binding and oxidative stress, especially upregulation of MT1 isoform genes. Our findings suggest that metals associated with PM, e.g., zinc, copper, and arsenic, induce MT-1 and may be the primary mediators for PM-induced oxidative stress. Keywords: in vitro exposure, PM2.5 particle treatment, human alveolar macrophages

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Project description:Surfactant protein D (SP-D) is a lung-specific protein, synthesized and secreted by lung epithelial cells. It belongs to group III of the family of C-type lectins; each member of this group has an unusual overall structure consisting of multiple globular 'head' regions (which contain the C-type lectin domains) linked by triple-helical, collagen-like, strands. This group includes the surfactant protein A (SP-A) and the serum proteins mannan-binding protein, conglutinin and collectin-43, all of which have been shown to bind to the C1q receptor found on a wide variety of cells, including macrophages. Both SP-D and SP-A have been shown to enhance oxygen radical production by alveolar macrophages. Although this strongly suggests a direct interaction between SP-D and a specific receptor on alveolar macrophages, it is still unclear whether SP-D binds to the same receptor used by SP-A and/or C1q. Human SP-D was isolated from amniotic fluid and was radiolabelled using 125I. Alveolar macrophages were isolated from human bronchioalveolar lavage fluid, and also from bovine lung washings, by differential adhesion to 24-well tissue-culture plates. The study was carried out using EDTA-containing buffers, to eliminate Ca(2+)-dependent C-type lectin binding, and was also carried out at 4 degrees C to eliminate possible internalization by the cells. 125I-SP-D showed specific binding to alveolar macrophages in both a time- and concentration-saturable manner. The binding was inhibited, by approx. 90%, on addition of a 200-fold excess of unlabelled SP-D. The apparent dissociation constant (Kd) was (3.6 +/- 1.3) x 10(-11) M, based on the assumption that native SP-D is assembled as a dodecamer of 12 identical polypeptides of 43 kDa to yield a protein of 516 kDa. C1q was also shown to bind alveolar macrophages (Kd 3 x 10(-6) M), but addition of C1q did not show inhibition of the binding of 125I-SP-D to the macrophages. We conclude that SP-D binds specifically to alveolar macrophages and the receptor involved is different from that utilized by C1q.

Dataset Information

Fine ambient particles induce oxidative stress and metal binding genes in human alveolar macrophages.

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Fine ambient particles induce oxidative stress and metal binding genes in human alveolar macrophages.

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