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Ambient particulate matter induces interleukin-8 expression through an alternative NF-?B (nuclear factor-kappa B) mechanism in human airway epithelial cells.

ABSTRACT: BACKGROUND: Exposure to ambient air particulate matter (PM) has been shown to increase rates of cardiopulmonary morbidity and mortality, but the underlying mechanisms are still not well understood. OBJECTIVE: We examined signaling events involved in the expression of the inflammatory gene interleukin-8 (IL-8) in human airway epithelial cells (HAECs) exposed to ambient PM collected in an urban area of Mexicali, Mexico. METHODS: We studied IL-8 expression and regulatory signaling pathways in cultured HAECs exposed to Mexicali PM suspended in media for 0-4 hr. RESULTS: Exposure resulted in a dose-dependent, 2- to 8-fold increase in IL-8 mRNA expression relative to controls. PM exposure induced IL-8 transcriptional activity in BEAS-2B cells that was dependent on the nuclear factor-kappa B (NF-?B) response element in the IL-8 promoter. Chromatin immunoprecipitation (ChIP) assays showed a 3-fold increase in binding of the p65 (RelA) NF-?B isoform to the IL-8 promoter sequence in HAECs exposed to PM. Western blot analyses showed elevated levels of phosphorylation of p65 but no changes in I?B? phosphorylation or degradation. IL-8 expression was blunted in a dose-dependent manner in BEAS-2B cells transduced with a lentivirus encoding a dominant negative p65 mutant in which phosphorylation sites were inactivated. CONCLUSION: Taken together, these findings show that the increase in IL-8 mRNA expression in HAECs exposed to PM10 (PM ? 10 ?m in aerodynamic diameter) is mediated through an NF-?B-dependent signaling mechanism that occurs through a pathway involving direct phosphorylation of the transcription factor p65 in the absence of I?B? degradation. These data show that exposure to PM10 in ambient air can induce inflammatory responses by activating specific signaling mechanisms in HAECs.

SUBMITTER: Silbajoris R

PROVIDER: S-EPMC3230452 | biostudies-literature | 2011 Oct

REPOSITORIES: biostudies-literature

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Ambient particulate matter induces interleukin-8 expression through an alternative NF-κB (nuclear factor-kappa B) mechanism in human airway epithelial cells.

Silbajoris Robert R Osornio-Vargas Alvaro R AR Simmons Steven O SO Reed William W Bromberg Philip A PA Dailey Lisa A LA Samet James M JM

Environmental health perspectives 20110610 10

<h4>Background</h4>Exposure to ambient air particulate matter (PM) has been shown to increase rates of cardiopulmonary morbidity and mortality, but the underlying mechanisms are still not well understood.<h4>Objective</h4>We examined signaling events involved in the expression of the inflammatory gene interleukin-8 (IL-8) in human airway epithelial cells (HAECs) exposed to ambient PM collected in an urban area of Mexicali, Mexico.<h4>Methods</h4>We studied IL-8 expression and regulatory signalin ...[more]

PMID: 21665565

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Project description:Murine Pulmonary Responses to Ambient Baltimore Particulate Matter: Genomic Analysis and Contribution to Airway Hyperresponsiveness Asthma is a complex disease characterized by airway hyperresponsiveness (AHR) and chronic airway inflammation. Environmental factors such as ambient particulate matter (PM), a major air pollutant, has been demonstrated in epidemiological studies to contribute to asthma exacerbation and increased asthma prevalence. OBJECTIVE: We investigated the genomic and pathophysiological effects of Baltimore PM (median diameter 1.78 µm) in a murine model of asthma to identify potential biomarkers. METHODS: A/J mice with ovalbumin (OVA) –induced AHR were exposed to PM (20 mg/kg, intratracheal), and both AHR and bronchoalveolar lavage (BAL) were assayed on days 1, 4, and 7 post exposure. Lung gene expression profiling (Affymetrix Mouse430_ 2.0) by PM (20 mg/kg, intratracheal) were assayed on OVA- and / or PM--challenged mice. RESULTS: Significant increases of airway responsiveness in OVA-treated mice were observed, indicating an asthmatic phenotype. Ambient PM exposure induced significant changes in AHR in both naive mice and OVA-induced asthmatic mice. In both naive and OVA challenged asthmatic mice, PM induced eosinophil and neutrophil infiltration into airways, elevated BAL protein content, and stimulated secretion of TH1 cytokines (IFN-g, IL-6, and TNF-a) and TH2 cytokines (IL-4, IL-5, and eotaxin) into BAL. Consistent with these results, PM induced expression of genes of innate immune response, chemotaxis and complementary system. CONCLUSION: These studies, consistent with epidemiological data, indicate that PM increases AHR and lung inflammation in naïve mice and exacerbates the asthma phenotype of increased AHR and gene expression pattern changes correlated with acute lung inflammation and airway damage. We used microarrays to detail the global programme of gene expression induced by rhPBEF treatment and VALI. Keywords: gene expression

Project description:Particulate matter (PM) is able to induce airway epithelial injury, while the detailed mechanisms remain unclear. Here we demonstrated that PM exposure inactivated MTOR (mechanistic target of rapamycin kinase), enhanced macroautophagy/autophagy, and impaired lysosomal activity in HBE (human bronchial epithelial) cells and in mouse airway epithelium. Genetic or pharmaceutical inhibition of MTOR significantly enhanced, while inhibition of autophagy attenuated, PM-induced IL6 expression in HBE cells. Consistently, club-cell-specific deletion of Mtor aggravated, whereas loss of Atg5 in bronchial epithelium reduced, PM-induced airway inflammation. Interestingly, the augmented inflammatory responses caused by MTOR deficiency were markedly attenuated by blockage of downstream autophagy both in vitro and in vivo. Mechanistically, the dysregulation of MTOR-autophagy signaling was partially dependent on activation of upstream TSC2, and interacted with the TLR4-MYD88 to orchestrate the downstream NFKB activity and to regulate the production of inflammatory cytokines in airway epithelium. Moreover, inhibition of autophagy reduced the expression of EPS15 and the subsequent endocytosis of PM. Taken together, the present study provides a mechanistic explanation for how airway epithelium localized MTOR-autophagy axis regulates PM-induced airway injury, suggesting that activation of MTOR and/or suppression of autophagy in local airway might be effective therapeutic strategies for PM-related airway disorders.Abbreviations: ACTB: actin beta; AKT: AKT serine/threonine kinase; ALI: air liquid interface; AP2: adaptor related protein complex 2; ATG: autophagy related; BALF: bronchoalveolar lavage fluid; COPD: chronic obstructive pulmonary disease; CXCL: C-X-C motif chemokine ligand; DOX: doxycycline; EGF: epidermal growth factor; EGFR: epidermal growth factor receptor; EPS15: epidermal growth factor receptor pathway substrate 15; HBE: human bronchial epithelial; H&E: hematoxylin & eosin; IKK: IKB kinase; IL: interleukin; LAMP2: lysosomal-associated membrane protein 2; LPS: lipopolysaccharide; MAP1LC3B/LC3B: microtubule-associated protein 1 light chain 3 beta; MTEC: mouse tracheal epithelial cells; MTOR: mechanistic target of rapamycin kinase; MYD88: MYD88 innate immune signal transduction adaptor; NFKB: nuclear factor of kappa B; NFKBIA: NFKB inhibitor alpha; PM: particulate matter; PtdIns3K: phosphatidylinositol 3-kinase; Rapa: rapamycin; RELA: RELA proto-oncogene, NFKB subunit; SCGB1A1: secretoglobin family 1A member 1; siRNA: small interfering RNAs; SQSTM1: sequestosome 1; TEM: transmission electronic microscopy; TLR4: toll like receptor 4; TSC2: TSC complex subunit 2.

Project description:Murine Pulmonary Responses to Ambient Baltimore Particulate Matter: Genomic Analysis and Contribution to Airway Hyperresponsiveness; Asthma is a complex disease characterized by airway hyperresponsiveness (AHR) and chronic airway inflammation. Environmental factors such as ambient particulate matter (PM), a major air pollutant, has been demonstrated in epidemiological studies to contribute to asthma exacerbation and increased asthma prevalence. OBJECTIVE: We investigated the genomic and pathophysiological effects of Baltimore PM (median diameter 1.78 Âµm) in a murine model of asthma to identify potential biomarkers. METHODS: A/J mice with ovalbumin (OVA) âinduced AHR were exposed to PM (20 mg/kg, intratracheal), and both AHR and bronchoalveolar lavage (BAL) were assayed on days 1, 4, and 7 post exposure. Lung gene expression profiling (Affymetrix Mouse430_ 2.0) by PM (20 mg/kg, intratracheal) were assayed on OVA- and / or PM--challenged mice. RESULTS: Significant increases of airway responsiveness in OVA-treated mice were observed, indicating an asthmatic phenotype. Ambient PM exposure induced significant changes in AHR in both naive mice and OVA-induced asthmatic mice. In both naive and OVA challenged asthmatic mice, PM induced eosinophil and neutrophil infiltration into airways, elevated BAL protein content, and stimulated secretion of TH1 cytokines (IFN-g, IL-6, and TNF-a) and TH2 cytokines (IL-4, IL-5, and eotaxin) into BAL. Consistent with these results, PM induced expression of genes of innate immune response, chemotaxis and complementary system. CONCLUSION: These studies, consistent with epidemiological data, indicate that PM increases AHR and lung inflammation in naÃ¯ve mice and exacerbates the asthma phenotype of increased AHR and gene expression pattern changes correlated with acute lung inflammation and airway damage. We used microarrays to detail the global programme of gene expression induced by rhPBEF treatment and VALI. Experiment Overall Design: animals were treated by PBS, Oval albumin, PM, or both OVA/PM

Dataset Information

Ambient particulate matter induces interleukin-8 expression through an alternative NF-?B (nuclear factor-kappa B) mechanism in human airway epithelial cells.

Publications

Ambient particulate matter induces interleukin-8 expression through an alternative NF-κB (nuclear factor-kappa B) mechanism in human airway epithelial cells.

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