Mice Fed a High DHA Diet Exhibit Increased Resolvin D1 and Altered Inflammatory Outcomes Following a Single Inhalational Exposure to Organic Dust Extract

Exposure to hog barn organic dust contributes to occupational lung diseases, which are mediated by inflammatory and oxidative stress pathways. Isoprostanes—a family of eicosanoids produced by oxidation of phospholipids by oxygen radicals—are biomarkers of pulmonary oxidative stress. Importantly, 8-isoprostane has been implicated as a key biomarker and mediator of oxidative stress because it is a potent pulmonary vasoconstrictor. Antioxidants found in fruits and vegetables hold promise for preventing or reducing effects of oxidative stress-related diseases including chronic bronchitis and chronic obstructive pulmonary disease (COPD). Here, we investigated 8-isoP and oxidant production by organic dust-exposed airway epithelial cells and the inhibitory effects of an extract from calyces of the sorrel plant, Hibiscus sabdariffa, on oxidant-producing pathways. Confluent cultures of normal human tracheobronchial epithelial cells were pretreated or not with 1% sorrel extract prior to 5% dust extract (DE) exposure. Following DE treatments, live cells, cell-free supernatants, or cell extracts were evaluated for the presence of 8-isoprostane, superoxide, hydrogen peroxide, nitric oxide, hydroxyl radical, peroxynitrite, and catalase activity to evaluate sorrel’s inhibitory effect on oxidative stress. The well-known radical scavenging antioxidant, N-acetyl cysteine (NAC), was used for comparisons with sorrel. DE exposure augmented the production of all radicals measured including 8-isoprostane (p value < 0.001), which could be inhibited by NAC or sorrel. Among reactive oxygen and nitrogen species generated in response to DE exposure, sorrel had no effect on H2O2 production and NAC had no significant effect on NO⋅ production. The observations reported here suggest a possible role for sorrel in preventing 8-isoprostane and oxidant-mediated stress responses in bronchial epithelial cells exposed to hog barn dust. These findings suggest a potential role for oxidative stress pathways in mediating occupational lung diseases and antioxidants within sorrel and NAC in reducing dust-mediated oxidative stress within the airways of exposed workers.

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Organic dust inhibits surfactant protein expression by reducing thyroid transcription factor-1 levels in human lung epithelial cells

Innate Immunity ◽

10.1177/1753425919827360 ◽

2019 ◽

Vol 25 (2) ◽

pp. 118-131 ◽

Cited By ~ 2

Author(s):

Kartiga Natarajan ◽

Keerthi Gangam ◽

Velmurugan Meganathan ◽

Koteswara R Gottipati ◽

Courtney Mitchell ◽

...

Keyword(s):

Epithelial Cells ◽

Respiratory Diseases ◽

Lung Epithelial Cells ◽

Organic Dust ◽

Protein Levels ◽

Thyroid Transcription Factor 1 ◽

Thyroid Transcription Factor ◽

Lung Epithelial ◽

Transcription Factor 1 ◽

Dust Extract

Exposure to organic dust is a risk factor for the development of respiratory diseases. Surfactant proteins (SP) reduce alveolar surface tension and modulate innate immune responses to control lung inflammation. Therefore, changes in SP levels could contribute to the development of organic-dust-induced respiratory diseases. Because information on the effects of organic dust on SP levels is lacking, we studied the effects of dust from a poultry farm on SP expression. We found that dust extract reduced SP-A and SP-B mRNA and protein levels in H441 human lung epithelial cells by inhibiting their promoter activities, but did not have any effect on SP-D protein levels. Dust extract also reduced SP-A and SP-C levels in primary human alveolar epithelial cells. The inhibitory effects were not due to LPS or protease activities present in dust extract or mediated via oxidative stress, but were dependent on a heat-labile factor(s). Thyroid transcription factor-1, a key transcriptional activator of SP expression, was reduced in dust-extract-treated cells, indicating that its down-regulation mediates inhibition of SP levels. Our study implies that down-regulation of SP levels by organic dust could contribute to the development of lung inflammation and respiratory diseases in humans.

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Transcriptional mechanisms and protein kinase signaling mediate organic dust induction of IL-8 expression in lung epithelial and THP-1 cells

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.00215.2014 ◽

2015 ◽

Vol 308 (1) ◽

pp. L11-L21 ◽

Cited By ~ 9

Author(s):

Koteswara R. Gottipati ◽

Shiva Kumar Bandari ◽

Matthew W. Nonnenmann ◽

Jeffrey L. Levin ◽

Gregory P. Dooley ◽

...

Keyword(s):

Protein Kinase ◽

Inflammatory Responses ◽

Dust Exposure ◽

Kinase Signaling ◽

Organic Dust ◽

Chronic Lung Diseases ◽

Lung Epithelial ◽

Poultry Dust ◽

Protein Kinase Signaling ◽

Dust Extract

Exposure to the agricultural work environment is a risk factor for the development of respiratory symptoms and chronic lung diseases. Inflammation is an important contributor to the pathogenesis of tissue injury and disease. Cellular and molecular mechanisms mediating lung inflammatory responses to agricultural dust are not yet fully understood. We studied the effects of poultry dust extract on molecular regulation of interleukin-8 (IL-8), a proinflammatory cytokine, in A549 and Beas2B lung epithelial and THP-1 monocytic cells. Our findings indicate that poultry dust extract potently induces IL-8 levels by increasing IL-8 gene transcription without altering IL-8 mRNA stability. Increase in IL-8 promoter activity was due to enhanced binding of activator protein 1 and NF-κB. IL-8 induction was associated with protein kinase C (PKC) and mitogen-activated protein kinase (MAPK) activation and inhibited by PKC and MAPK inhibitors. IL-8 increase was not inhibited by polymyxin B or l-nitroarginine methyl ester, indicating lack of involvement of lipopolysaccharide and nitric oxide in the induction. Lung epithelial and THP-1 cells share common mechanisms for induction of IL-8 levels. Our findings identify key roles for transcriptional mechanisms and protein kinase signaling pathways for IL-8 induction and provide insights into the mechanisms regulating lung inflammatory responses to organic dust exposure.

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Gene expression profiling of the effects of organic dust in lung epithelial and THP-1 cells reveals inductive effects on inflammatory and immune response genes

Physiological Genomics ◽

10.1152/physiolgenomics.00096.2015 ◽

2016 ◽

Vol 48 (4) ◽

pp. 281-289 ◽

Cited By ~ 8

Author(s):

Vijay Boggaram ◽

David S. Loose ◽

Koteswara R. Gottipati ◽

Kartiga Natarajan ◽

Courtney T. Mitchell

Keyword(s):

Gene Expression ◽

Inflammatory Responses ◽

Expression Profiles ◽

Gene Expression Profiles ◽

Organic Dust ◽

Monocytic Cells ◽

Lung Epithelial ◽

Poultry Dust ◽

Induced Changes ◽

Dust Extract

The intensification and concentration of animal production operations expose workers to high levels of organic dusts in the work environment. Exposure to organic dusts is a risk factor for the development of acute and chronic respiratory symptoms and diseases. Lung epithelium plays important roles in the control of immune and inflammatory responses to environmental agents to maintain lung health. To better understand the effects of organic dust on lung inflammatory responses, we characterized the gene expression profiles of A549 alveolar and Beas2B bronchial epithelial and THP-1 monocytic cells influenced by exposure to poultry dust extract by DNA microarray analysis using Illumina Human HT-12 v4 Expression BeadChip. We found that A549 alveolar and Beas2B bronchial epithelial and THP-1 cells responded with unique changes in the gene expression profiles with regulation of genes encoding inflammatory cytokines, chemokines, and other inflammatory proteins being common to all the three cells. Significantly induced genes included IL-8, IL-6, IL-1β, ICAM-1, CCL2, CCL5, TLR4, and PTGS2. Validation by real-time qRT-PCR, ELISA, Western immunoblotting, and immunohistochemical staining of lung sections from mice exposed to dust extract validated DNA microarray results. Pathway analysis indicated that dust extract induced changes in gene expression influenced functions related to cellular growth and proliferation, cell death and survival, and cellular development. These data show that a broad range of inflammatory mediators produced in response to poultry dust exposure can modulate lung immune and inflammatory responses. This is the first report on organic dust induced changes in expression profiles in lung epithelial and THP-1 monocytic cells.

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Organic dust induces inflammatory gene expression in lung epithelial cells via ROS-dependent STAT-3 activation

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.00448.2018 ◽

2019 ◽

Vol 317 (1) ◽

pp. L127-L140 ◽

Cited By ~ 1

Author(s):

Kartiga Natarajan ◽

Velmurugan Meganathan ◽

Courtney Mitchell ◽

Vijay Boggaram

Keyword(s):

Epithelial Cells ◽

Inflammatory Mediators ◽

Tyrosine Kinases ◽

Inflammatory Mediator ◽

Organic Dust ◽

Poultry Dust ◽

Chemical Inhibition ◽

Sirna Knockdown ◽

Mouse Lungs ◽

Dust Extract

Exposure to dust in agricultural and animal environments, known as organic dust, is associated with the development of respiratory symptoms and respiratory diseases. Inflammation is a key feature of lung pathologies associated with organic dust exposure, and exposure to organic dust induces the expression of several immune and inflammatory mediators. However, information on transcription factors and cellular and molecular mechanisms controlling the production of immune and inflammatory mediators induced by organic dust is limited. In this study, we have identified STAT-3 as an important transcription factor controlling the induction of expression of immune and inflammatory mediators by poultry dust extracts in airway epithelial cells and in mouse lungs and delineated the cellular pathway for STAT-3 activation. Poultry dust extract activated STAT-3 phosphorylation in Beas2B and normal human bronchial epithelial cells and in mouse lungs. Chemical inhibition and siRNA knockdown of STAT-3 suppressed induction of immune and inflammatory mediator expression. Antioxidants suppressed the increase of STAT-3 phosphorylation induced by poultry dust extract indicating that oxidative stress [elevated reactive oxygen species (ROS) levels] is important for the activation. Chemical inhibition and siRNA knockdown experiments demonstrated that STAT-3 activation is dependent on the activation of nonreceptor tyrosine-protein kinase 2 (TYK2) and epidermal growth factor receptor (EGFR) tyrosine kinases. Our studies show that poultry dust extract controls the induction of immune and inflammatory mediator expression via a cellular pathway involving oxidative stress-mediated STAT-3 activation by TYK2 and EGFR tyrosine kinases.

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