Effect of exposure to swine dust on levels of IL-8 in airway lavage fluid

Assessment of the circulating inflammatory mediator interleukin-8 in dogs with tracheal collapse

Objective

Tracheal collapse (TC) is an obstructive respiratory disorder in dogs that can affect lifespan and quality of life. Systemic inflammation has been identified in other obstructive airway conditions in dogs and humans. We hypothesized a systemic pro-inflammatory state exists in dogs with TC.

Animals

Dogs with TC (TC, n = 15) and healthy, non-affected controls (C, n = 15), were prospectively enrolled.

Procedure

Signalment and body condition score (BCS) were recorded for all dogs. For TC dogs, cough duration, pharyngeal collapse, bronchial collapse, and previous stent placement were recorded. Plasma samples were banked at -80°C and batch-analyzed for interleukin-8 (IL-8). Differences between groups were evaluated.

Results

Yorkshire terriers were overrepresented in the TC group. The TC group was older than the C group and had a higher BCS. Interleukin-8 was significantly greater in the TC compared to the C group. Interleukin-8 was not correlated with age sex, BCS, breed, cough duration, pharyngeal collapse, bronchial collapse, or stent placement.

Conclusion and clinical relevance

Increased plasma IL-8 concentration supports the presence of systemic inflammation in canine TC. Dogs with TC were older than controls, with a higher BCS, but this did not account for the increased IL-8. Further investigation of IL-8 as a potential biomarker for monitoring TC progression and therapeutic response is warranted.

Intranasal and Serum Gentamicin Concentration: Comparison of Three Topical Administration Protocols in Dogs

Antimicrobials' topical administration efficacy has not been assessed in dogs with upper respiratory tract disease. The aim was to compare the concentration of gentamicin in nasal lavage fluid (NALF) and in serum after three topical protocols. This was a prospective crossover study of ten healthy dogs. Gentamicin was nebulized for a duration of 1 week, twice a day, for 10 min in the first protocol (10-min protocol) and for 3 min in the second protocol (3-min protocol), while the third protocol consisted of the administration of 0.25 mL of gentamicin in each nostril (drop protocol). Median concentrations of gentamicin in NALF were 9.39 µg/mL (8.12-19.97 interquartile range), 4.96 µg/mL (4.60-6.43) and 137.00 µg/mL (110.5-162.00) in the 10-min protocol, 3-min protocol and drop protocol, respectively. The result for the drop protocol was significantly higher than those of both nebulization protocols in NALF (p = 0.039). In serum, the gentamicin concentration was 0.98 µg/mL (0.65-1.53) and 0.25 µg/mL (0.25-0.44) in the 10-min and 3-min protocols, respectively. Gentamicin was not detected in the serum of seven out of ten dogs in the drop protocol, and gentamicin was significantly higher in the 10-min protocol compared to the drop protocol (p = 0.001). This study found that the 10-min, 3-min and drop protocols achieved superior concentrations in NALF compared to the minimum inhibitory concentration for gentamicin-sensitive bacteria, while remaining below the toxic values in blood.

Purification and characterization of a serine protease from organic dust and elucidation of its inductive effects on lung inflammatory mediators

Organic dust inhalation is associated with the development of respiratory diseases. Serine protease activities in organic dusts were previously reported to contribute to the induction of lung inflammatory mediators however, the identities of the proteases and the mechanisms by which they induce inflammatory mediators are unknown. The goal of this study was to purify and characterize serine protease(s) from organic dust and elucidate mechanisms by which they induce lung inflammatory mediators. A serine protease was purified from poultry organic dust by benzamidine-agarose affinity chromatography. Mass spectrometry and amino-terminal sequence analysis identified the purified protease as chicken trypsin II-P29. Purified protease induced proinflammatory cytokine levels in Beas2B and NHBE epithelial and THP-1 macrophage cells. Treatment with the purified protease increased cellular and mitochondrial reactive oxygen species (ROS) generation. Induction of inflammatory mediators and ROS were suppressed by serine protease inhibitors and antioxidants. Purified protease activated protein kinase C (PKC), mitogen-activated protein kinase (MAPK)1/3 and MAPK14 signaling, and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and signal transducer and activator of transcription 3 (Stat-3), and chemical inhibitors targeting these pathways suppressed induction of inflammatory mediators. Calcium mobilization studies showed that the purified protease activated protease-activated receptors (PAR) F2R, F2RL1, F2RL2, F2RL3, and F2R and F2RL1 knockdown suppressed the induction of inflammatory mediators. Intranasal instillation of purified protease increased lung chemokine (C-X-C motif) ligand (CXCL)1, interleukin (IL)-6, and tumor necrosis factor (TNF) levels in mice. Our studies have shown that chicken trypsin is a proinflammatory constituent of poultry organic dust, and induces lung inflammatory mediators via increased ROS and PAR activation in a cell signaling pathway involving PKC, MAPK1/3 and MAPK14, and NF-κB and Stat-3.NEW & NOTEWORTHY Inhalation of dust in industrial agricultural operations is linked to the development of lung diseases. Our studies have isolated for the first time a trypsin protease from poultry farm dust and have shown that it stimulates lung inflammation. The protease stimulates the production of oxidants and cell signaling pathways to increase inflammatory mediator production. Targeting trypsin protease in poultry farm environment may be a useful strategy to counter the harmful effects of dust.

Lipid-Sensing Receptor FFAR4 Modulates Pulmonary Epithelial Homeostasis following Immunogenic Exposures Independently of the FFAR4 Ligand Docosahexaenoic Acid (DHA)

The role of pulmonary free fatty acid receptor 4 (FFAR4) is not fully elucidated and we aimed to clarify the impact of FFAR4 on the pulmonary immune response and return to homeostasis. We employed a known high-risk human pulmonary immunogenic exposure to extracts of dust from swine confinement facilities (DE). WT and Ffar4-null mice were repetitively exposed to DE via intranasal instillation and supplemented with docosahexaenoic acid (DHA) by oral gavage. We sought to understand if previous findings of DHA-mediated attenuation of the DE-induced inflammatory response are FFAR4-dependent. We identified that DHA mediates anti-inflammatory effects independent of FFAR4 expression, and that DE-exposed mice lacking FFAR4 had reduced immune cells in the airways, epithelial dysplasia, and impaired pulmonary barrier integrity. Analysis of transcripts using an immunology gene expression panel revealed a role for FFAR4 in lungs related to innate immune initiation of inflammation, cytoprotection, and immune cell migration. Ultimately, the presence of FFAR4 in the lung may regulate cell survival and repair following immune injury, suggestive of potential therapeutic directions for pulmonary disease.

NADPH and xanthine oxidases control induction of inflammatory mediator expression by organic dust in the lung

Exposure to organic dust in animal and agricultural farms and the ensuing lung inflammation are linked to the development of respiratory diseases. We found previously that elevated production of reactive oxygen species (ROS) by aqueous poultry organic dust extract (hereafter referred to as dust extract) mediates induction of proinflammatory mediators in airway epithelial cells. In the present study, we investigated whether ROS generated by NADPH oxidases (NOX) and xanthine oxidase (XO) controls induction of inflammatory mediators by dust extract and the underlying mechanisms in bronchial epithelial cells. Using chemical inhibitors and siRNA targeted knockdown, we found that NOX1, NOX2, NOX4, and XO-derived ROS regulates induction of proinflammatory mediator levels. Like airway epithelial cells in vitro, NOX inhibitor VAS2870 reduced keratinocyte chemoattractant (KC), IL-6, and TNF-α production and 4-hydroxynonenal (4-HNE) staining induced by dust extract in mouse lungs. VAS2870 inhibition of proinflammatory mediators was associated with reduced NFκB and Stat3 activation indicating that NOX generated ROS activates NFκB and Stat3 to induce proinflammatory gene expression. Dust extract increased the membrane association of p47^phox in airway epithelial cells indicating NOX2 activation but had no effect on NOX2 protein levels. In summary, our studies have shown that NOX and XO generated ROS control organic dust induction of proinflammatory mediators in airway epithelial cells via NFκB and Stat3 activation.

Bacterial extracellular vesicles isolated from organic dust induce neutrophilic inflammation in the lung

Inhalation of organic dust is an occupational hazard leading to the development of respiratory symptoms and respiratory diseases. Bioaerosols from concentrated animal feeding operations are rich in bacteria and could carry bacterial extracellular vesicles (EVs) that could induce lung inflammation. It is not known if organic dust contains bacterial EVs and whether they modulate lung inflammation. Herein, we show that poultry organic dust contains bacterial EVs (dust EVs) that induce lung inflammation. Treatment of airway epithelial cells, THP-1-monocytes and -macrophages with dust EVs rapidly induced IL-8, IL-6, ICAM-1, proIL-1β, and TNF-α levels. In airway epithelial cells, induction of inflammatory mediators was due to increased mRNA levels and NF-κB activation. Induction of inflammatory mediators by dust EVs was not inhibited by polymyxin B. Single and repeated treatments of mice with dust EVs increased lung KC, IL-6, and TNF-α levels without significantly altering IL-17A levels. Increases in cytokines were associated with enhanced neutrophil infiltration into the lung. Repeated treatments of mice with dust EVs increased lung mean linear intercept and increased collagen deposition around airways indicating lung remodeling. Peribronchial cell infiltrates and airway epithelial thickening were also observed in treated mice. Because bacterial EVs are nanometer-sized particles, they can reach and accumulate in the bronchiolar and alveolar regions causing lung injury leading to the development of respiratory diseases. Our studies have provided new evidence for the presence of bacterial EVs in organic dust and for their role as one of the causative agents of organic dust-induced lung inflammation and lung injury.

Livestock farm particulate matter enhances airway inflammation in mice with or without allergic airway disease

Effects of airborne biological particulate matter (BioPM; from livestock farms) on the pulmonary airways are not well studied. The aim of the present study was to investigate whether fine (<2.5 μm) BioPM derived from indoor animal stables (two chicken and two pig farms) could modify airway allergic responses by using a mouse model of allergic airway disease (allergic asthma). After intraperitoneal ovalbumin (OVA) sensitization mice were either intranasally challenged with OVA (allergic mice) or saline (non-allergic controls). Mice were also intranasally treated with farm-derived BioPM. Bronchoalveolar lavage fluid (BALF), blood and lung tissues were collected one day after intranasal exposure. BioPM from all the farms caused an acute neutrophilic inflammatory response in non-allergic mice. In allergic mice, BioPM derived from pig farm 2 induced a larger cellular inflammatory response than other farm-derived BioPM. All farm BioPM elicited Th17 cytokine (Interleukin (IL)-23) production except chicken farm 2, whereas Th2 cytokine (IL-5) increase was only induced by BioPM collected from chicken farm 2. These results indicate the exposure of BioPM from chicken and pig farms may cause the enhancement of airway allergic response in mice following exposure to OVA. More variation in the responses between farms was observed in allergic than non-allergic mice. Understanding the source and doses of BioPM that may affect the airway allergic response could help susceptible individuals to avoid worsening their respiratory diseases.

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

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.

Organic barn dust inhibits surfactant protein D production through protein kinase-c alpha dependent increase of GPR116

Prolonged exposure to organic barn dusts can lead to chronic inflammation and a broad range of lung problems over time, mediated by innate immune mechanisms. The immune surfactant or collectin surfactant protein D (SP-D) is a crucial multifunctional innate immune receptor. Little work to date has examined the effect of such collectins in response to organic dusts. We provide evidence here that agricultural organic dusts can inhibit mRNA and protein expression of SP-D in a human alveolar epithelial cell line, and an in vivo mouse model. This inhibition was not a result of lipopolysaccharide (LPS) or peptidoglycans, the two most commonly cited immune active components of these dusts. We further show that inhibition of the signaling molecule protein kinase C alpha (PKCα) can reverse this inhibition implicating it as a mechanism of SP-D inhibition. Examination of the SP-D regulatory receptor GPR116 showed that its mRNA expression was increased in response to dust and inhibited by blocking PKCα, implicating it as a means of inhibiting SP-D in the lungs in response to organic dusts. This reduction shows that organic barn dust can reduce lung SP-D, thus leaving workers potentially at risk for a host of pathogens.

Cholinergic mechanisms in an organic dust model simulating an acute exacerbation in patients with COPD

Background

Exposure in a pig barn induces airway inflammation that has similarities with the response observed in acute exacerbations in COPD.

Methods

A total of 15 smokers with COPD and 15 healthy non-smokers were exposed for 2 hours in a pig barn (in vivo exposure). Symptoms were assessed, lung function measured, and blood and sputum samples taken before and after exposure. Blood neutrophils were isolated and stimulated ex vivo with dust from a pig barn and acetylcholine, and inflammatory markers were analyzed.

Results

In vivo exposure caused more symptoms and greater lung function fall in COPD patients than in controls. Baseline concentrations of MMP9, TIMP1, IL6, CXCL8, in sputum and neutrophil blood count were higher in COPD patients than in controls. In vivo exposure increased MMP9, TIMP1, IL6, CXCL8, TNFα, and LTB₄ in sputum and MMP9 and IL6 in blood, with no difference between the groups, and serum CRP increased more in COPD subjects. Expression of choline acetyltransferase and acetylcholinesterase on sputum and blood cells was similar in the groups and uninfluenced by in vivo exposure. Dust exposure ex vivo increased choline acetyltransferase expression in neutrophils, but the dust and acetylcholine response did not differ between the groups before and after in vivo exposure.

Conclusion

COPD patients exposed in a pig barn experience symptoms similar to those in acute exacerbations and lung function deterioration that is unrelated to bronchial responsiveness. Cholinergic mechanisms are involved in the inflammatory response to dust, with no difference between COPD and non-smokers.

Effects of tiotropium bromide on airway hyperresponsiveness and inflammation in mice exposed to organic dust

INTRODUCTION

Acute exposure to organic dust (OD) in pig barns induces intense airway inflammation with neutrophilia and hyperresponsiveness. This reaction is likely associated with increased cholinergic activity. Therefore, the involvement of cholinergic mechanisms in the reaction to acute exposure of OD was investigated in mice using the long-acting muscarinic antagonist tiotropium.

METHODS

BALB/c mice received tiotropium (2-200 ng) intranasally on day 1 of the study. On days 2-4, mice received vehicle or OD (25 μg) intranasally. Airway hyperresponsiveness to methacholine was assessed 24 h following the last OD exposure. Bronchoalveolar lavage (BAL) fluid, lung tissue and blood were collected for analyses.

RESULTS

Organic dust elevated airway responsiveness to methacholine compared with controls (PBS) assessed as Newtonian resistance (1.5 ± 0.1 vs 0.9 ± 0.1 cm H₂O x s/mL), tissue damping (12.4 ± 1.4 vs 8.9 ± 0.9 cm H₂O∙s/mL) and tissue elastance (41.1 ± 5.3 vs 27.2 ± 2.5 cm H₂O∙s/mL). Tiotropium (200 ng) decreased the Newtonian resistance and tissue damping after exposure to PBS or OD. Organic dust exposure increased inflammatory cells in BAL fluid by almost 400%, mainly due to neutrophil influx, which was unaffected by tiotropium. Organic dust increased levels of mainly Th1 mediators. Tiotropium treatment attenuated OD-induced release of IL-2, IL-4 and IL-6.

CONCLUSIONS

Tiotropium decreased the OD-induced increase of specific cytokines without influencing the OD-induced increase of airway responsiveness and neutrophil infiltration into the lungs. We conclude that the cholinergic pathway contributes to the pro-inflammatory effects caused by inhalation of OD from pig barns.

Cohort profile: the Saskatchewan Rural Health Study-adult component

OBJECTIVES

Less is known about the respiratory health of general farming and non-framing populations. A longitudinal Saskatchewan Rural Health Study (SRHS) was conducted to explore the association between individual and contextual factors with respiratory health outcomes in these populations. Hence, the objectives are to: (i) describe the updated methodology of longitudinal SRHS-an extension of baseline survey methodology published earlier; (ii) compare baseline characteristics and the prevalences of respiratory health outcomes between drops-outs and completers; and (iii) summarize key findings based on baseline survey data.

RESULTS

The SRHS was a prospective cohort study conducted in two phases: baseline survey in 2010 and a follow-up in 2014. Each survey consisted of two components, self-administered questionnaire and clinical assessments. At baseline, 8261 participants (≥ 18 years) (4624 households) and at follow-up, 4867 participants (2797 households) completed the questionnaires. Clinical assessments on lung functions and/or allergies were conducted among a sub-group of participants from both the surveys. To date, we published 15 peer-reviewed manuscripts and 40 abstracts in conference proceedings. Findings from the study will improve the knowledge of respiratory disease etiology and assist in the development and targeting of prevention programs for rural populations in Saskatchewan, Canada.

Effect of low-level CO2 on innate inflammatory protein response to organic dust from swine confinement barns

BACKGROUND

Organic hog barn dust (HDE) exposure induces lung inflammation and long-term decreases in lung function in agricultural workers. While concentrations of common gasses in confined animal facilities are well characterized, few studies have been done addressing if exposure to elevated barn gasses impacts the lung immune response to organic dusts. Given the well documented effects of hypercapnia at much higher levels we hypothesized that CO2 at 8 h exposure limit levels (5000 ppm) could alter innate immune responses to HDE.

METHODS

Using a mouse model, C57BL/6 mice were nasally instilled with defined barn dust extracts and then housed in an exposure box maintained at one of several CO2 levels for six hours. Bronchiolar lavage (BAL) was tested for several cytokines while lung tissue was saved for mRNA purification and immunohistochemistry.

RESULTS

Exposure to elevated CO2 significantly increased the expression of pro-inflammatory markers, IL-6 and KC, in BAL fluid as compared to dust exposure alone. Expression of other pro-inflammatory markers, such as ICAM-1 and matrix metalloproteinase-9 (MMP-9), were also tested and showed similar increased expression upon HDE + CO2 exposure. A chemokine array analysis of BAL fluid revealed that MIP-1γ (CCL9) shows a similar increased response to HDE + CO2. Further testing showed CCL9 was significantly elevated by barn dust and further enhanced by CO2 co-exposure in a dose-dependent manner that was noticeable at the protein and mRNA levels. In all cases, except for ICAM-1, increases in tested markers in the presence of elevated CO2 were only significant in the presence of HDE as well.

CONCLUSIONS

We show that even at mandated safe exposure limits, CO2 is capable of enhancing multiple markers of inflammation in response to HDE.

Proteases and oxidant stress control organic dust induction of inflammatory gene expression in lung epithelial cells

Background

Persistant inflammatory responses to infectious agents and other components in organic dust underlie lung injury and development of respiratory diseases. Organic dust components responsible for eliciting inflammation and the mechanisms by which they cause lung inflammation are not fully understood. We studied the mechanisms by which protease activities in poultry dust extracts and intracellular oxidant stress induce inflammatory gene expression in A549 and Beas2B lung epithelial cells.

Methods

The effects of dust extracts on inflammatory gene expression were analyzed by quantitative polymerase chain reaction (qPCR), enzyme linked immunosorbent (ELISA) and western blot assays. Oxidant stress was probed by dihydroethidium (DHE) labeling, and immunostaining for 4-hydroxynonenal (4-HNE). Effects on interleukin-8 (IL-8) promoter regulation were determined by transient transfection assay.

Results

Dust extracts contained trypsin and elastase activities, and activated protease activated receptor (PAR)-1 and -2. Serine protease inhibitors and PAR-1 or PAR-2 knockdown suppressed inflammatory gene induction. Dust extract induction of IL-8 gene expression was associated with increased DHE-fluorescence and 4-HNE staining, and antioxidants suppressed inflammatory gene induction. Protease inhibitors and antioxidants suppressed protein kinase C and NF-κB activation and induction of IL-8 promoter activity in cells exposed to dust extract.

Conclusions

Our studies demonstrate that proteases and intracellular oxidants control organic dust induction of inflammatory gene expression in lung epithelial cells. Targeting proteases and oxidant stress may serve as novel approaches for the treatment of organic dust induced lung diseases. This is the first report on the involvement of oxidant stress in the induction of inflammatory gene expression by organic dust.

Electronic supplementary material

The online version of this article (doi:10.1186/s12931-016-0455-z) contains supplementary material, which is available to authorized users.

Impact of tobacco smoking on cytokine signaling via interleukin-17A in the peripheral airways

There is excessive accumulation of neutrophils in the airways in chronic obstructive pulmonary disease (COPD) but the underlying mechanisms remain poorly understood. It is known that extracellular cytokine signaling via interleukin (IL)-17A contributes to neutrophil accumulation in the airways but nothing is known about the impact of tobacco smoking on extracellular signaling via IL-17A. Here, we characterized the impact of tobacco smoking on extracellular cytokine signaling via IL-17A in the peripheral airways in long-term smokers with and without COPD and in occasional smokers before and after short-term exposure to tobacco smoke. We quantified concentrations of IL-17A protein in cell-free bronchoalveolar lavage (BAL) fluid samples (Immuno-quantitative PCR) and cytotoxic T-cells (immunoreactivity for CD8⁺ and CD3⁺) in bronchial biopsies. Matrix metalloproteinase-8 and human beta defensin 2 proteins were also quantified (enzyme-linked immunosorbent assay) in the BAL samples. The concentrations of IL-17A in BAL fluid were higher in long-term smokers without COPD compared with nonsmoking healthy controls, whereas those with COPD did not differ significantly from either of the other groups. Short-term exposure to tobacco smoke did not induce sustained alterations in these concentrations in occasional smokers. Long-term smokers displayed higher concentrations of IL-17A than did occasional smokers. Moreover, these concentrations correlated with CD8⁺ and CD3⁺ cells in biopsies among long-term smokers with COPD. In healthy nonsmokers, BAL concentrations of matrix metalloproteinase-8 and IL-17A correlated, whereas this was not the case in the pooled group of long-term smokers with and without COPD. In contrast, BAL concentrations of human beta defensin 2 and IL-17A correlated in all study groups. This study implies that long-term but not short-term exposure to tobacco smoke increases extracellular cytokine signaling via IL-17A in the peripheral airways. In the smokers with COPD, this signaling may involve cytotoxic T-cells. Long-term exposure to tobacco smoke leads to a disturbed association of extracellular IL-17A signaling and matrix metalloproteinase-8, of potential importance for the coordination of antibacterial activity.

β2-Adrenergic agonists attenuate organic dust-induced lung inflammation

Agricultural dust exposure results in significant lung inflammation, and individuals working in concentrated animal feeding operations (CAFOs) are at risk for chronic airway inflammatory diseases. Exposure of bronchial epithelial cells to aqueous extracts of hog CAFO dusts (HDE) leads to inflammatory cytokine production that is driven by protein kinase C (PKC) activation. cAMP-dependent protein kinase (PKA)-activating agents can inhibit PKC activation in epithelial cells, leading to reduced inflammatory cytokine production following HDE exposure. β2-Adrenergic receptor agonists (β2-agonists) activate PKA, and we hypothesized that β2-agonists would beneficially impact HDE-induced adverse airway inflammatory consequences. Bronchial epithelial cells were cultured with the short-acting β2-agonist salbutamol or the long-acting β2-agonist salmeterol prior to stimulation with HDE. β2-Agonist treatment significantly increased PKA activation and significantly decreased HDE-stimulated IL-6 and IL-8 production in a concentration- and time-dependent manner. Salbutamol treatment significantly reduced HDE-induced intracellular adhesion molecule-1 expression and neutrophil adhesion to epithelial cells. Using an established intranasal inhalation exposure model, we found that salbutamol pretreatment reduced airway neutrophil influx and IL-6, TNF-α, CXCL1, and CXCL2 release in bronchoalveolar lavage fluid following a one-time exposure to HDE. Likewise, when mice were pretreated daily with salbutamol prior to HDE exposure for 3 wk, HDE-induced neutrophil influx and inflammatory mediator production were also reduced. The severity of HDE-induced lung pathology in mice repetitively exposed to HDE for 3 wk was also decreased with daily salbutamol pretreatment. Together, these results support the need for future clinical investigations to evaluate the utility of β2-agonist therapies in the treatment of airway inflammation associated with CAFO dust exposure.

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

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.

Industrial Food Animal Production and Community Health

Industrial food animal production (IFAP) is a source of environmental microbial and chemical hazards. A growing body of literature suggests that populations living near these operations and manure-applied crop fields are at elevated risk for several health outcomes. We reviewed the literature published since 2000 and identified four health outcomes consistently and positively associated with living near IFAP: respiratory outcomes, methicillin-resistant Staphylococcus aureus (MRSA), Q fever, and stress/mood. We found moderate evidence of an association of IFAP with quality of life and limited evidence of an association with cognitive impairment, Clostridium difficile, Enterococcus, birth outcomes, and hypertension. Distance-based exposure metrics were used by 17/33 studies reviewed. Future work should investigate exposure through drinking water and must improve exposure assessment with direct environmental sampling, modeling, and high-resolution DNA typing methods. Investigators should not limit study to high-profile pathogens like MRSA but include a broader range of pathogens, as well as other disease outcomes.

Neutrophilic oxidative stress mediates organic dust-induced pulmonary inflammation and airway hyperresponsiveness

Airway exposure to organic dust (OD) from swine confinement facilities induces airway inflammation dominated by neutrophils and airway hyperresponsiveness (AHR). One important neutrophilic innate defense mechanism is the induction of oxidative stress. Therefore, we hypothesized that neutrophils exacerbate airway dysfunction following OD exposure by increasing oxidant burden. BALB/C mice were given intranasal challenges with OD or PBS (1/day for 3 days). Mice were untreated or treated with a neutrophil-depleting antibody, anti-Ly6G, or the antioxidant dimethylthiourea (DMTU) prior to OD exposure. Twenty-four hours after the final exposure, we measured airway responsiveness in response to methacholine (MCh) and collected bronchoalveolar lavage fluid to assess pulmonary inflammation and total antioxidant capacity. Lung tissue was harvested to examine the effect of OD-induced antioxidant gene expression and the effect of anti-Ly6G or DMTU. OD exposure induced a dose-dependent increase of airway responsiveness, a neutrophilic pulmonary inflammation, and secretion of keratinocyte cytokine. Depletion of neutrophils reduced OD-induced AHR. DMTU prevented pulmonary inflammation involving macrophages and neutrophils. Neutrophil depletion and DMTU were highly effective in preventing OD-induced AHR affecting large, conducting airways and tissue elastance. OD induced an increase in total antioxidant capacity and mRNA levels of NRF-2-dependent antioxidant genes, effects that are prevented by administration of DMTU and neutrophil depletion. We conclude that an increase in oxidative stress and neutrophilia is critical in the induction of OD-induced AHR. Prevention of oxidative stress diminishes neutrophil influx and AHR, suggesting that mechanisms driving OD-induced AHR may be dependent on neutrophil-mediated oxidant pathways.

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

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.

Compartment differences of inflammatory activity in chronic obstructive pulmonary disease

Background

Chronic obstructive pulmonary disease (COPD) is associated with local and systemic inflammation. The knowledge of interaction and co-variation of the inflammatory responses in different compartments is meagre.

Method

Healthy controls (n = 23), smokers with (n = 28) and without (n = 29) COPD performed spirometry and dental examinations. Saliva, induced sputum, bronchoalveolar lavage (BAL) fluid and serum were collected. Inflammatory markers were assessed in all compartments using ELISA, flow cytometry and RT-PCR.

Results

Negative correlations between lung function and saliva IL-8 and matrix metalloproteinase-9 (MMP-9) were found in smokers with COPD. IL-8 and MMP-9 in saliva correlated positively with periodontal disease as assessed by gingival bleeding in non-smokers.

Tumor necrosis factor-α (TNF-α) in saliva, serum and TNF-α mRNA expression on macrophages in BAL-fluid were lower in smokers than in non-smokers. There were positive correlations between soluble TNF-α receptor 1 (sTNFR1) and soluble TNF-α receptor 2 (sTNFR2) in sputum, BAL-fluid and serum in all groups. Sputum interleukin-8 (IL-8) or interleukin-6 (IL-6) was positively correlated with sTNFR1 or sTNFR2 in non-smokers and with sTNFR2 in COPD.

Conclusion

Saliva which is convenient to collect and analyse, may be suitable for biomarker assessment of disease activity in COPD. An attenuated TNF-α expression was demonstrated by both protein and mRNA analyses in different compartments suggesting that TNF-α response is altered in moderate and severe COPD. Shedding of TNFR1 or TNFR2 is similarly regulated irrespective of airflow limitation.

Dimethylarginine dimethylaminohydrolase (DDAH) overexpression attenuates agricultural organic dust extract-induced inflammation

Modern, industrialized farming practices have lead to working conditions that include high levels of airborne dust. Agricultural workers inhale these complex organic dusts on a daily basis, leading to airway inflammation and higher risk for developing chronic obstructive pulmonary disease. The mechanisms regulating the organic dust-induced airway inflammatory response are not well-defined. We investigated whether overexpression of dimethylarginine dimethylaminohydrolase (DDAH) would lead to diminished pulmonary inflammation in an animal model of organic dust extract exposure. We instilled wild-type (WT) and DDAH overexpressing mice with an aqueous organic dust extract (ODE) collected from a swine confinement building. We found that inflammatory indices such as neutrophil influx and inflammatory cytokine production was lower in the DDAH overexpressing mice compared to WT after organic dust extract (ODE) instillation. We went on to determine how DDAH was mediating the decrease in inflammation induced by ODE. PKCα and PKCε play an essential role in the ODE inflammatory response. In a model of lung slices from WT and DDAH overexpressing mice, we demonstrated an increase in PKCα and PKCε in the WT mice exposed to ODE. This increase was diminished in the DDAH overexpressing mice exposed to ODE. We also tested an important component of the ODE, peptidoglycan (PGN). We noted a similar decrease in neutrophils and inflammatory cytokines in the DDAH overexpressing animals instilled with PGN compared to WT. In conclusion, our studies found a role for DDAH in regulating the ODE-triggered activation of epithelial PKCα and PKCε, a previously unrecognized mechanism of action. This ultimately results in diminished pulmonary inflammation.

Shifted T-cell polarisation after agricultural dust exposure in mice and men

RATIONALE

A low prevalence of asthma and atopy has been shown in farmers and agricultural workers. However, in these workers, a higher prevalence of respiratory symptoms has been reported, in which T helper 1 (Th1) and/or Th17 responses may play a role.

AIM

We investigated the effect of exposure to dust extracts (DEs) from different farms on airway inflammation and T-cell polarisation in a mouse model and assessed T-cell polarisation in agricultural workers from the same farms.

METHODS

DEs were prepared from settled dust collected at cattle and pig farms and bulb and onion industries. Mice were exposed to phosphate-buffered saline (PBS), DEs, house dust mite (HDM) or HDM+DE via nasal instillation, four times per week during 5 weeks. Hyperresponsiveness, airway inflammation, IgE levels and T-cell polarisation were assessed. Th-cell and T cytotoxic (Tc)-cell subsets were investigated in peripheral blood samples from 33 agricultural workers and 9 non-exposed controls.

RESULTS

DEs induced interleukin(IL)-17, IL-1β and IL-6 in mouse lung homogenates. DE-exposed mice had more mixed inflammatory infiltrates in the lungs, and more neutrophils compared with PBS-exposed mice. DEs protected against the HDM-induced Th2 response and methacholine hyperresponsiveness. Interestingly, occupationally exposed humans had higher frequencies of Th cells spontaneously expressing IL-17 and interferon γ compared with controls.

CONCLUSION

Chronic exposure to different types of farm dust induces a Th/Tc-17 inflammatory response in mice and agricultural workers. This may contribute to the low prevalence of Th2-related diseases but may constitute a risk for other chronic respiratory diseases.

Organic barn dust extract exposure impairs porcine macrophage function in vitro: implications for respiratory health

Respiratory diseases are responsible for a significant amount of animal morbidity and mortality in the swine industry, including the majority of nursery and grower/finisher deaths. Innate immunity, including the maintenance of lung macrophage health and function, is an important defense mechanism against respiratory pathogens and their associated losses. Chronic exposure of swine industry workers to airborne barn dust results in significant predisposition to airway diseases and impairment of alveolar macrophage (AMφ) function. Because of their importance in maintaining normal respiratory function, this study was designed to evaluate the impact of barn dust on swine macrophages. As measures of macrophage function, we evaluated the activation of NF-κB, cytokine production, cell surface marker expression and the phagocytic and antibacterial capabilities of porcine macrophages after in vitro exposure to an organic swine barn dust extract (ODE). ODE treatment induced AMφ secretion of both pro- and anti-inflammatory cytokines, suggesting a complex activation profile. Additionally, ODE induced expression of genes (TLR2, NOD2) involved in sensing Gram-positive bacteria, a major component of barn dust. ODE exposure also enhanced the expression of several cell surface markers of activation, including a receptor for the porcine reproductive and respiratory syndrome virus. Moreover, two key functions of AMϕ, phagocytosis and bacterial killing, were impaired after exposure to ODE. Treatment with ODE for the first 72 h of differentiation also inhibited the ability of monocyte-derived macrophages to translocate NF-κB to the nucleus following endotoxin stimulation. Taken together, these results demonstrate, for the first time, that organic dust extract exposure negatively affects pig macrophage activation and function, potentially enhancing host susceptibility to a variety of respiratory infections.

Maresin-1 reduces the pro-inflammatory response of bronchial epithelial cells to organic dust

Background

Exposure to organic dust causes detrimental airway inflammation. Current preventative and therapeutic measures do not adequately treat resulting disease, necessitating novel therapeutic interventions. Recently identified mediators derived from polyunsaturated fatty acids exhibit anti-inflammatory and pro-resolving actions. We tested the potential of one of these mediators, maresin-1 (MaR1), in reducing organic dust-associated airway inflammation.

Methods

As bronchial epithelial cells (BECs) are pivotal in initiating organic dust-induced inflammation, we investigated the in vitro effects of MaR1 on a human BEC cell line (BEAS-2B). Cells were pretreated for 1 hour with 0–200 nM MaR1, followed by 1–24 hour treatment with 5% hog confinement facility-derived organic dust extract (HDE). Alternatively, a mouse lung slice model was utilized in supportive cytokine studies. Supernatants were harvested and cytokine levels determined via enzyme-linked immunosorbent assays. Epithelial cell protein kinase C (PKC) isoforms α and ϵ, and PKA activities were assessed via radioactivity assays, and NFκB and MAPK-related signaling mechanisms were investigated using luciferase vector reporters.

Results

MaR1 dose-dependently reduced IL-6 and IL-8 production following HDE treatment of BECs. MaR1 also reduced HDE-stimulated cytokine release including TNF-α in a mouse lung slice model when given before or following HDE treatment. Previous studies have established that HDE sequentially activates epithelial PKCα and PKCϵ at 1 and 6 hours, respectively that regulated TNF-α, IL-6, and IL-8 release. MaR1 pretreatment abrogated these HDE-induced PKC activities. Furthermore, HDE treatment over a 24-hour period revealed temporal increases in NFκB, AP-1, SP-1, and SRE DNA binding activities, using luciferase reporter assays. MaR1 pretreatment did not alter the activation of NFκB, AP-1, or SP-1, but did reduce the activation of DNA binding at SRE.

Conclusions

These observations indicate a role for MaR1 in attenuating the pro-inflammatory responses of BECs to organic dust extract, through a mechanism that does not appear to rely on reduced NFκB, AP-1, or SP-1-related signaling, but may be mediated partly through SRE-related signaling. These data offer insights for a novel mechanistic action of MaR1 in bronchial epithelial cells, and support future in vivo studies to test MaR1’s utility in reducing the deleterious inflammatory effects of environmental dust exposures.

Adhesion molecules in subjects with COPD and healthy non-smokers: a cross sectional parallel group study

Background

The aim of the study was to investigate how the expression of adhesion molecules changes as neutrophils migrate from the circulation to the lung and if these changes differ between non-smoking subjects and smokers with and without COPD.

Methods

Non-smoking healthy subjects (n=22), smokers without (n=21) and with COPD (n=18) were included. Neutrophils from peripheral blood, sputum and bronchial biopsies were analysed for cell surface expression of adhesion molecules (CD11b, CD62L, CD162). Serum, sputum supernatant and BAL-fluid were analysed for soluble adhesion molecules (ICAM-1, -3, E-selectin, P-selectin, VCAM-1, PECAM-1).

Results

Expression of CD11b was increased on circulating neutrophils from smokers with COPD. It was also increased on sputum neutrophils in both smokers groups, but not in non-smokers, as compared to circulating neutrophils.

Serum ICAM-1 was higher in the COPD group compared to the other two groups (p<0.05) and PECAM-1 was lower in smokers without COPD than in non-smoking controls and the COPD group (p<0.05). In BAL-fluid ICAM-1 was lower in the COPD group than in the other groups (p<0.05).

Conclusions

Thus, our data strongly support the involvement of a systemic component in COPD and demonstrate that in smokers neutrophils are activated to a greater extent at the point of transition from the circulation into the lungs than in non-smokers.

Respiratory health effects of large animal farming environments

With increases in large animal-feeding operations to meet consumer demand, adverse upper and lower respiratory health effects in exposed agriculture workers are a concern. The aim of this study was to review large animal confinement feeding operational exposures associated with respiratory disease with a focus on recent advances in the knowledge of causative factors and cellular and immunological mechanisms. A PubMed search was conducted with the keywords airway, farm, swine, dairy, horse, cattle inflammation, organic dust, endotoxin, and peptidoglycan, among items were published between 1980 and now. Articles were selected based on their relevance to environmental exposure and reference to airway diseases. Airway diseases included rhinitis, sinusitis, mucus membrane inflammation syndrome, asthma, chronic bronchitis, chronic obstructive pulmonary disease, hypersensitivity pneumonitis, and organic dust toxic syndrome. There is lower prevalence of immunoglobulin (Ig) E-mediated asthma and atopy in farmers and their children, but organic dust worsens existing asthma. Multiple etiologic factors are linked to disease, including allergens, organic dusts, endotoxins, peptidoglycans, and gases. Large animal confinement feeding operations contain a wide diversity of microbes with increasing focus on gram-positive bacteria and archaebacteria as opposed to gram-negative bacteria in mediating disease. Toll-like receptors (TLR) and nucleotide oligomerization domain (NOD)-like innate immune pathways respond to these exposures. Finally, a chronic inflammatory adaptation, tolerance-like response in chronically exposed workers occurs. Large animal confinement farming exposures produce a wide spectrum of upper and lower respiratory tract diseases due to the complex diversity of organic dust, particulates, microbial cell wall components, and gases and resultant activation of various innate immune receptor signaling pathways.

Chemokine release by neutrophils in chronic obstructive pulmonary disease

Neutrophils are among the first cells to arrive at the site of injury. Chemokines secreted by neutrophils affect the migration of both neutrophils and other inflammatory cells, such as monocytes. It has been reported that LPS-induced release of IL-8 (CXCL-8) by neutrophils is amplified by neutrophil-derived TNF-α. We hypothesize that chemokine release by neutrophils is altered in chronic obstructive pulmonary disease (COPD) compared with healthy controls and that TNF-α may be involved in this alteration. Peripheral blood neutrophils isolated from smokers with COPD (n = 12), smokers without COPD (n = 12) and healthy, non-smokers (n = 12) were stimulated with LPS, TNF-α or organic dust. Anti-TNF-α Ab (infliximab) was used to study the effect of neutrophil-derived TNF-α. Release of CXCL-8, macrophage inflammatory protein-1 α (MIP-1α, CCL-3), monocyte chemotactic protein-1 (MCP-1, CCL-2) and TNF-α was measured. Neutrophils spontaneously released CXCL-8, CCL-2 and CCL-3. Inhibition of TNF-α reduced the spontaneous release of CXCL-8 and CCL-3. Stimulation with LPS and organic dust increased the release of CXCL-8 and CCL-3 (but not CCL-2) which was reduced by inhibition of TNF-α. In the COPD group, inhibition of TNF-α failed to inhibit the release of LPS-induced CXCL-8. The role of neutrophils as cytokine and chemokine producers was confirmed. Neutrophil-derived TNF-α contributed to the release of chemokines after stimulation with LPS and organic dust, as the response was inhibited by infliximab. In the COPD group, infliximab did not significantly inhibit the release of CXCL-8, suggesting that the role of TNF-α is altered in COPD.

Effect of Toll-like receptor 4 gene polymorphisms on work-related respiratory symptoms and sensitization to wheat flour in bakery workers

BACKGROUND

Bakery workers are exposed to flour allergens and endotoxins, which interact to induce allergic responses and respiratory symptoms. We hypothesized that Toll-like receptor 4 (TLR4) may be involved in the development of work-related respiratory symptoms and sensitization to wheat flour.

OBJECTIVE

To investigate the genetic contribution of TLR4 to respiratory symptoms and sensitization to wheat flour in bakery workers, we performed a genetic association study of TLR4 in Korean bakery workers.

METHODS

A total of 381 workers completed a questionnaire regarding work-related symptoms. Skin prick tests with common and occupational allergens were done, and specific antibodies to wheat flour were measured by enzyme-linked immunosorbent assay. Two single-nucleotide polymorphisms (SNPs) of the TLR4 gene (-2027A>G and -1608T>C) were genotyped, and the functional effects of the polymorphisms were analyzed using the luciferase reporter and electrophoretic mobility shift assay.

RESULTS

Homozygotes for the -2027G and -1608C alleles exhibited a lower prevalence of work-related lower respiratory symptoms than carriers of the -2027AA/AG (P = .007) and -1608TT/TC (P =.021) genotypes. Furthermore, haplotype analysis indicated that workers with the haplotype 2, ht2 [GC], had fewer work-related lower respiratory symptoms (P = .021). The ht2 [GC] construct showed lower promoter activity than the haplotype 1, ht1[AT], in both BEAS-2B (P = .001) and U937 cells (P = .007).

CONCLUSION

Bakery workers carrying the TLR4 variants are at lower risk of developing work-related chest symptoms. This finding suggests that the TLR4 gene may be involved in allergic sensitization to wheat flour as well as endotoxin-induced respiratory symptoms in endotoxin-allergen-exposed workers and that carriers of TLR4 variants are less affected by environmental exposure.

Toll-like receptor expression in smokers with and without COPD

INTRODUCTION

Chronic obstructive pulmonary disease (COPD) is characterized by non-reversible airflow limitation and systemic engagement. Bacterial colonization in the lungs is common in COPD-patients and may be associated with frequent acute exacerbations. Pattern-recognition receptors (PRRs), like Toll-like receptor 2 (TLR2), TLR4 and CD14 are expressed on most immunologic active cell types and are most likely of importance in COPD patho-physiology.

MATERIAL AND METHODS

Twenty smokers with and 20 without COPD and 20 healthy non-smokers participated in the study. At two visits, induced sputum was collected after spirometry, blood was sampled and bronchoscopy with bronchoalveolar lavage was performed. Expression of TLR2, TLR4 and CD14 on different cell types and soluble receptors were assessed in the different compartments.

RESULTS

Expression of TLR2 was lower on sputum neutrophils and soluble TLR2 (sTLR2) was higher in the supernatant in the COPD group, indicating a down regulation of TLR2 at the transit from blood to sputum. Expression of CD14 on sputum neutrophils and gene expression of CD14 on alveolar macrophages was up-regulated in the two smoking groups compared with non-smokers. No differences between the groups were found regarding TLR4 expression.

CONCLUSIONS

Pattern-recognition receptors (PRRs), that are expected to make a first line of defense against invading micro-organisms, are differently regulated in smokers with COPD compared with smokers without airflow limitation and non-smokers. This is likely of importance in COPD patho-physiology, in particular for exacerbations, which often are caused by micro-organisms.

Budesonide enhances Toll-like receptor 2 expression in activated bronchial epithelial cells

Endotoxin, tumor necrosis factor (TNF), and organic dust constitute proinflammatory stimuli involved in the initiation of inflammation. The major receptor for endotoxin (lipopolysaccharide [LPS]) is Toll-like receptor 4 (TLR4), whereas TLR2 binds to agents from gram-positive bacteria. The aim of the study was to elucidate whether TLR2 and TLR4, expressed on primary bronchial epithelial cells (PBECs), are influenced by exogenous (organic dust and LPS) and endogenous (TNF) stimuli and whether this interaction is influenced by a glucocorticosteroid. The cells were exposed to LPS (10 microg/ml), TNF (10 ng/ml), or dust (100 microg/ml) 1.5 and 6 h, in the presence or absence of budesonide (10(-6) M) in vitro. The mRNA expression of interleukin (IL)-6, IL-8, TLR2, and TLR4 were measured with real-time reverse transcriptase-polymerase chain reaction (RT-PCR) and IL-6 and IL-8 release was assessed with enzyme-linked immunosorbent assay (ELISA). To elucidate the importance of TLR-signaling for IL-6 and IL-8 secretion, the effect of TLR-blockers was studied. Endotoxin, TNF, and dust stimulated the release of IL-6 and IL-8 in a time-dependent manner. Budesonide significantly attenuated the release and expression of IL-6 and IL-8 after exposure. Budesonide did not influence TLR expression, but costimulation with LPS, TNF, or dust together with budesonide increased TLR2 expression synergistically. Blocking of TLR2 and TLR4 reduced cytokine secretion in stimulated cells. Budesonide reduced IL-6 and IL-8 production and enhanced expression of TLR2 in PBECs only in the presence of a proinflammatory stimulus. These findings contribute to our understanding of the beneficial effects of glucocorticosteroids during chronic obstructive pulmonary disease (COPD) exacerbations and asthma, which are frequently caused by microorganisms.

Sequential activation of protein kinase C isoforms by organic dust is mediated by tumor necrosis factor

Dust samples collected from Nebraska swine confinement facilities (hog dust extract [HDE]) are known to elicit proinflammatory cytokine release from human bronchial epithelial (HBE) cells in vitro. This response involves the activation of two protein kinase C (PKC) isoforms: PKCalpha and PKCepsilon. Experiments were designed to investigate the relationship between the two isoenzymes and the degree to which each is responsible for cytokine release in HBE. Experiments also examined the contribution of TNF-alpha to IL-6 and IL-8 release. PKCalpha and PKCepsilon activities were inhibited using isoform-specific pharmacologic inhibitors and genetically modified dominant-negative (DN) expressing cell lines. Release of the proinflammatory cytokines IL-6, IL-8, and TNF-alpha was measured and PKC isoform activities assessed. We found that HDE stimulates PKCalpha activity by 1 hour, and within 6 hours the activity returns to baseline. PKCalpha-specific inhibitor or PKCalphaDN cells abolish this HDE-mediated effect. Both IL-6 and IL-8 release are likewise diminished under these conditions compared with normal HBE, and treatment with TNF-alpha-neutralizing antibody does not further inhibit cytokine release. In contrast, PKCepsilon activity was enhanced by 6 hours after HDE treatment. TNF-alpha blockade abrogated this effect. HDE-stimulated IL-6, but not IL-8 release in PKCepsilonDN cells. The concentration of TNF-alpha released by HDE-stimulated HBE is sufficient to have a potent cytokine-eliciting effect. A time course of TNF-alpha release suggests that TNF-alpha is produced after PKCalpha activation, but before PKCepsilon. These results suggest a temporal ordering of events responsible for the release of cytokines, which initiate and exacerbate inflammatory events in the airways of people exposed to agricultural dust.

Lung responses to secondary endotoxin challenge in rats exposed to pig barn air

BACKGROUND

Swine barn air contains endotoxin and many other noxious agents. Single or multiple exposures to pig barn air induces lung inflammation and loss of lung function. However, we do not know the effect of exposure to pig barn air on inflammatory response in the lungs following a secondary infection. Therefore, we tested a hypothesis that single or multiple exposures to barn air will result in exaggerated lung inflammation in response to a secondary insult with Escherichia coli LPS (E. coli LPS).

METHODS

We exposed Sprague-Dawley rats to ambient (N = 12) or swine barn air (N = 24) for one or five days and then half (N = 6/group) of these rats received intravenous E. coli LPS challenge, observed for six hours and then euthanized to collect lung tissues for histology, immunohistochemistry and ELISA to assess lung inflammation.

RESULTS

Compared to controls, histological signs of lung inflammation were evident in barn exposed rat lungs. Rats exposed to barn air for one or five days and challenged with E. coli LPS showed increased recruitment of granulocytes compared to those exposed only to the barn. Control, one and five day barn exposed rats that were challenged with E. coli LPS showed higher levels of IL-1beta in the lungs compared to respective groups not challenged with E. coli LPS. The levels of TNF-alpha in the lungs did not differ among any of the groups. Control rats without E. coli LPS challenge showed higher levels of TGF-beta2 compared to controls challenged with E. coli LPS.

CONCLUSION

These results show that lungs of rats exposed to pig barn air retain the ability to respond to E. coli LPS challenge.

Fluticasone and ibuprofen do not add to the effect of salmeterol on organic dust-induced airway inflammation and bronchial hyper-responsiveness

BACKGROUND

Exposure in a pig house causes airway inflammation and bronchial hyper-responsiveness which are not influenced by anti-asthma drugs, including a beta(2)-agonist (salmeterol).

OBJECTIVES

We hypothesized that a glucocorticoid or a cyclo-oxygenase-inhibitor synergistically interacts with salmeterol offering a protection against dust-induced increased bronchial responsiveness and airway inflammation. As data did not confirm previous results a retrospective analysis of pooled data on dust-induced bronchial hyper-responsiveness from four other studies was performed.

DESIGN

Fluticasone or ibuprofen was administered for 1 week and salmeterol or placebo was inhaled 1 h prior to a 3-h exposure in a pig barn in a double-blind, placebo-controlled, cross-over design (2-3 weeks apart) in 12 healthy subjects. Lung function, bronchial responsiveness to methacholine and inflammatory markers were evaluated before and after exposure. Pre- and postexposure bronchial responsiveness in nontreated subjects was retrospectively evaluated from four previous studies.

SUBJECTS

Twelve healthy, nonatopic nonsmokers.

RESULTS

Salmeterol partially protected against bronchial hyper-responsiveness but did not influence inflammatory markers. Fluticasone and ibuprofen did not add to these effects. The retrospective analysis showed that PD(20)FEV(1) after exposure in a pig barn is almost totally independent of pre-exposure PD(20)FEV(1)-level; all subjects end up at the same low postexposure PD(20)FEV(1).

CONCLUSION

Contradictory to our previous results, salmeterol offered partial protection against enhanced bronchial responsiveness induced by exposure in a pig barn. This effect was not modified by fluticasone or ibuprofen. Our data clearly demonstrate that interventions altering bronchial responsiveness must be compared between groups with similar prechallenge bronchial responsiveness or in a cross-over design.

Reproducibility of Nasal Lavage in the Context of the Inhalation Challenge Investigation of Occupational Rhinitis

Background

The nasal lavage (NAL) method is increasingly used to assess changes in upper airways inflammation in the investigation of occupational rhinitis (OR). A good reproducibility of the method is fundamental to accurately assess changes in markers of inflammation in nasal secretions before and after inhalation challenges. The main objective of this study was to assess the short-term reproducibility of cells and cellular markers of inflammation in NAL in the setting of specific inhalation challenge (SIC) investigating OR. An ancillary objective was to assess the reproducibility of NAL in the context of two different SIC methodologies.

Methods

Twenty-five subjects attended the laboratory for 2 separate days of NAL performed within the same week. On the first visit subjects underwent NAL before a SIC sham session and on the second visit before a SIC with the active agent. These prechallenge NAL measurements obtained on both days were used to analyze the reproducibility of the NAL method.

Results

The reproducibility for cell differential counts was satisfactory for neutrophils (intraclass correlation coefficient [ICC] = 0.68), for eosinophils (ICC = 0.95), for macrophages (ICC = 0.77), and for epithelial cells (ICC = 0.73). The reproducibility of total cell counting was poor (ICC = 0.12). The reproducibility of ECP concentrations was satisfactory (ICC = 0.67). Eosinophil counts were reproducible in the context of two different challenge methodologies.

Conclusion

The NAL method was shown to be sufficiently reproducible to be considered useful for the monitoring of upper airways inflammation during the investigation of OR by SIC.

Role of Toll-like receptor 4 in lung inflammation following exposure to swine barn air

The authors tested a hypothesis that lung inflammation and airway hyperresponsiveness (AHR) induced following barn air exposure are dependent on Toll-like receptor 4 (TLR4) by exposing C3HeB/FeJ (intact TLR4, wild type [WT]) and C3H/HeJ (defective TLR4, mutant) mice either to the barn air (8 hours/day for 1, 5, or 20 days) or ambient air. Both strains of mice, compared to their respective controls, showed increased AHR following 5 exposures but dampened AHR after 20 exposures to show lack of effect of TLR4 on AHR. However, swine barn air induced lung inflammation with recruitment of inflammatory cells and cytokine expression was observed in WT but not in mutant mice. These data show different roles of TLR4 in lung inflammation and AHR in mice exposed to swine barn air.

Lung inflammation following a single exposure to swine barn air

Background

Exposure to swine barn air is an occupational hazard. Barn workers following an eight-hour work shift develop many signs of lung dysfunction including lung inflammation. However, the in situ cellular and molecular mechanisms responsible for lung dysfunction induced following exposure to the barn air remain largely unknown. Specifically, the recruitment and role of pulmonary intravascular monocytes/macrophages (PIMMs), which increase host susceptibility for acute lung inflammation, remain unknown in barn air induced lung inflammation. We hypothesized that barn exposure induces recruitment of PIMMs and increases susceptibility for acute lung inflammation with a secondary challenge.

Methods

Sprague-Dawley rats were exposed either to the barn or ambient air for eight hours and were euthanized at various time intervals to collect blood, broncho-alveolar lavage fluid (BALF) and lung tissue. Subsequently, following an eight hour barn or ambient air exposure, rats were challenged either with Escherichia coli (E. coli) lipopolysaccharide (LPS) or saline and euthanized 6 hours post-LPS or saline treatment. We used ANOVA (P < 0.05 means significant) to compare group differences.

Results

An eight-hour exposure to barn air induced acute lung inflammation with recruitment of granulocytes and PIMMs. Granulocyte and PIMM numbers peaked at one and 48 hour post-exposure, respectively.

Secondary challenge with E. coli LPS at 48 hour following barn exposure resulted in intense lung inflammation, greater numbers of granulocytes, increased number of cells positive for TNF-α and decreased amounts of TGF-β2 in lung tissues. We also localized TNF-α, IL-1β and TGF-β2 in PIMMs.

Conclusion

A single exposure to barn air induces lung inflammation with recruitment of PIMMs and granulocytes. Recruited PIMMs may be linked to more robust lung inflammation in barn-exposed rats exposed to LPS. These data may have implications of workers exposed to the barn air who may encounter secondary microbial challenge.

Effect of formoterol and salmeterol on IL-6 and IL-8 release in airway epithelial cells

Beta(2)-adrenoceptors are widely distributed and occur on airway epithelial cells. The aim of this study was to find out whether the two long-acting beta(2)-agonists formoterol and salmeterol influence interleukin-6 (IL-6) and -8 (IL-8) release from airway epithelial cells in vitro. A549 cells and primary bronchial epithelial cells (PBEC) were stimulated with organic dust from pig barns. Non-stimulated and dust-stimulated cells were incubated for 24h with formoterol or salmeterol (10(-13)-10(-6)M) and the release of IL-6 and IL-8 into the medium was assessed by ELISA technique. Propranolol (10(-5)M) or sotalol (10(-3)M) were used to block the beta(2)-agonist mediated effects. Formoterol and salmeterol both induced enhancement of IL-6 and IL-8 release and added to the effect of organic dust. This enhanced release was blocked by a beta-blocker in PBEC but not in A549 cells. To our knowledge, this is the first time beta(2)-agonists have been shown to stimulate IL-6 release from airway epithelial cells. The results indicate different mechanisms of beta(2)-agonist action in bronchial and alveolar epithelial cells. Furthermore, our results indicate that A549 cells do not possess functional beta(2)-adrenoceptors.

Differential Pattern of Human Blood Neutrophil Activation After Stimulation With Organic Dust in Vitro and in Vivo

OBJECTIVE

To study activation of blood neutrophils in subjects after in vitro and in vivo stimulation.

METHODS

Blood from healthy volunteers was collected before and after their exposure to organic dust in a pig farm. Surface markers of neutrophil activation were analyzed by flow cytometry.

RESULTS

In vivo, there was a diurnal variation in basal levels of CD11b. Swine dust exposure increased the number of blood neutrophils and the levels of myeloperoxidase without effects on CD11b or Cys-X-Cys receptor 1 (CXCR-1) expression. However, a positive correlation between changes of myeloperoxidase and CD11b expression was observed. In vitro, N-formyl-methionyl-leucyl-phenylalanine (fMLP), lipopolysaccharide (LPS), leukotriene (LT)B4, LTD4, and swine dust stimulated the expression of CD11b. fMLP, LPS, and LTB4 diminished the expression of CXCR-1.

CONCLUSIONS

Exposure to swine dust in vitro activated neutrophils and inhalation of swine dust caused neutrophilia.

Respiratory response to endotoxin and dust predicts evidence of inflammatory response in volunteers in a swine barn

BACKGROUND

It has been shown that exposure in intense exposure in swine barn facilities is associated with increased respiratory symptoms and reduction in pulmonary functions. This study investigated if systemic response could be predicted by FEV(1) response following swine barn exposure.

METHODS

Naïve males were tested at baseline, low and high endotoxin and dust levels. Subjects were classified as "more responsive" (n = 9) or "less responsive" (n = 11) based on FEV(1) reduction following high endotoxin exposure. Health measures included pulmonary function testing, blood samples and nasal lavage. Environmental samples were collected from the barn.

RESULTS

White blood cells and blood lymphocytes at low exposure were significantly greater in those who were "more responsive" compared to those who were "less responsive". There was a significant increase in blood lymphocytes, serum IL6, total nasal lavage cells and nasal IL8 at high exposure among "more responsive" subjects compared to "less responsive" subjects.

CONCLUSIONS

Respiratory response to high-level endotoxin and dust exposure predicts evidence of inflammatory response throughout a range of endotoxin and dust exposures.

Pulmonary effects of exposure to pig barn air

Swine production has undergone rapid transformation from family owned operation to a large scale industrial enterprise. Since increasing number of pigs are reared on a large scale in confined buildings, some of the swine barn workers may be employed to work eight hours per day. Swine barn workers suffer from higher incidences of impaired air flow and lung inflammation, which is attributed to high intensity and interrupted exposures to pig barn air. The air in these barns contains gases, dust, microbes and endotoxin with endotoxin being the major suspect as the cause of lung dysfunction. This review attempts to describe the current state of knowledge of incidences and mechanisms of pulmonary dysfunction following exposure to the barn air.

Salmeterol Does Not Alter Increased Bronchial Responsiveness Caused by Organic Dust Exposure

BACKGROUND

Exposure in a swine house induces airway inflammation and increases bronchial responsiveness to methacholine in healthy subjects.

STUDY OBJECTIVES

The aim was to investigate whether a long-acting beta2-agonist, salmeterol, alters the increased bronchial responsiveness induced in healthy subjects following exposure to organic dust in a swine barn.

DESIGN AND SUBJECTS

The study includes three separate parts. In the first part (part 1), healthy subjects inhaled salmeterol (50 microg bid, n = 8) or placebo (n = 8) over 2 weeks. In part 2, healthy subjects inhaled one single dose of salmeterol (100 microg, n = 6) or placebo (n = 6) 1 h prior to exposure in a swine barn, which was followed by a bronchial methacholine challenge. In part 3, eight healthy individuals inhaled placebo or salmeterol (100 microg), 2 h or 8 h prior to a bronchial methacholine provocation, without being exposed in the swine barn.

RESULTS

Exposure caused an increase of bronchial responsiveness to methacholine by 3.2 doubling concentration steps (25 to 75th percentiles, 2.8 to 4.1) and 2.6 doubling concentration steps (25 to 75th percentiles, 1.4 to 3.7) in the placebo and salmeterol groups (2 weeks), respectively, with no significant differences between the groups (p = 0.3; part 1). Similar results were obtained when salmeterol was administered as a single dose (part 2) prior to exposure. However, salmeterol significantly attenuated the bronchial responsiveness to methacholine by 1.2 doubling concentration steps (0.8 to 1.7) 8 h after inhalation (part 3).

CONCLUSIONS

Salmeterol inhalation did not protect against the increased bronchial responsiveness induced in healthy subjects following exposure to organic dust when administered for 2 weeks or as a single dose prior to exposure. This lack of protection cannot be explained by homologous beta2-adrenoceptor desensitization. We hypothesize that exposure to organic material may alter the airway response to beta2-agonists.

Effects of 5-lipoxygenase inhibitor zileuton on airway responses to inhaled swine house dust in healthy subjects

BACKGROUND

Inhalation of swine house dust induces acute airway inflammation and increased bronchial responsiveness in healthy subjects.

OBJECTIVE

The aim of the study was to investigate whether 5-lipoxygenase products such as leukotrienes may have a role in this reaction.

METHODS

Twenty-three healthy subjects were randomised into two groups receiving treatment with either zileuton (600 mg) or placebo four times a day. After 5 days of treatment, all subjects were exposed for 3h in a swine barn. Bronchial responsiveness, exhaled nitric oxide (NO), and mediators in nasal lavage (NAL), blood and urine were measured before and after the exposure.

RESULTS

The exposure induced an increased bronchial responsiveness to methacholine in both groups with 2-3 doubling concentration steps, no significant difference between treatments. Leukotriene E(4) in urine increased significantly following exposure in the placebo group from 37.3 (29.1-45.6) (mean (95% confidence interval)) ng/mmol creatinine to 47.7 (36.3-59.0) ng/mmol creatinine (P<0.05), but not in the zileuton group. The post-exposure increase of LTB(4) levels in NAL fluid was totally abolished in the zileuton group (P<0.05 vs. the placebo). The levels of exhaled NO increased significantly (P<0.01), two-fold in both groups. The PGD(2) metabolite 9alpha, 11beta-PGF(2) increased in placebo-treated subjects (P<0.01; P<0.05 vs. zileuton), strengthening mast cell participation. Neutrophil counts and levels of IL-6 in peripheral blood increased in both groups, with a significantly larger increase in zileuton treated subjects (P<0.05 and P<0.001, respectively compared to placebo).

CONCLUSIONS

Pre-treatment with clinically recommended doses of the 5-lipoxygenase inhibitor zileuton did not affect the increase of bronchial reactivity induced by swine dust exposure. The intervention totally abolished the LTB(4) release in NAL fluid, but only partially inhibited the formation of leukotrienes as monitored by urinary levels. The enhanced increase of neutrophils and IL-6 in peripheral blood in the zileuton group, suggests that inhibition of 5-lipoxygenase may have pro-inflammatory effects.

Interleukin-17A mRNA and protein expression within cells from the human bronchoalveolar space after exposure to organic dust

BACKGROUND

In mice, the cytokine interleukin (IL)-17A causes a local accumulation of neutrophils within the bronchoalveolar space. IL-17A may thereby also contribute to an increased local proteolytic burden. In the current study, we determined whether mRNA for IL-17A is elevated and protein expression of IL-17A occurs locally in inflammatory cells within the human bronchoalveolar space during severe inflammation caused by organic dust. We also assessed the expression of the elastinolytic protease MMP-9 in this airway compartment.

METHODS

Six healthy, non-smoking human volunteers were exposed to organic dust in a swine confinement, a potent stimulus of neutrophil accumulation within the human bronchoalveolar space. Bronchoalveolar lavage (BAL) fluid was harvested 2 weeks before and 24 hours after the exposure and total and differential counts were conducted for inflammatory BAL cells. Messenger RNA for IL-17A was measured using reverse transcript polymerase chain reaction-enzyme linked immunoassay (RT-PCR-ELISA). Intracellular immunoreactivity (IR) for IL-17A and MMP-9, respectively, was determined in BAL cells.

RESULTS

The exposure to organic dust caused more than a forty-fold increase of mRNA for IL-17A in BAL cells. IL-17A immunoreactivity was detected mainly in BAL lymphocytes, and the number of these IL-17A expressing lymphocytes displayed an eight-fold increase, even though not statistically significant. The increase in IL-17A mRNA was associated with a substantial increase of the number of BAL neutrophils expressing MMP-9 immunoreactivity.

CONCLUSION

Exposure to organic dust increases local IL-17A mRNA and because there is intracellular expression in BAL lymphocytes, this suggests that IL-17A protein can originate from lymphocytes within the human bronchoalveolar space. The fact that the increased IL-17A mRNA is associated with an increased number of MMP-9-expressing neutrophils is compatible with IL-17A increasing the local proteolytic burden through its neutrophil-accumulating effect.

Symptomatic effects of exposure to diluted air sampled from a swine confinement atmosphere on healthy human subjects

Aerial emissions from a swine house at North Carolina State University's field laboratory were diluted to a level that could occur at varying distances downwind from a confined animal feeding operation (CAFO) both within and beyond the property line, and these emissions were delivered to an environmental exposure chamber. The study design consisted of two 1-hr sessions, one in which 48 healthy human adult volunteers were exposed to diluted swine air and another in which they were exposed to clean air (control). Objective measures of blood pressure, temperature, heart rate, respiratory rate, lung function, nasal inflammation, secretory immunity, mood, attention, and memory were correlated with objective measures of air quality. Ratings of perceived (self-reported) health symptoms were also obtained. The mean levels of airborne constituents in the swine air condition were hydrogen sulfide (24 ppb), ammonia (817 ppb), total suspended particulates (0.0241 mg/m3), endotoxin (7.40 endotoxin units/m3), and odor (57 times above odor threshold). No statistical differences on objective measures of physical symptoms, mood, or attention resulted from the 1-hr exposure to swine emissions in the environmental chamber when compared with clean air for healthy human volunteers. However, subjects were 4.1 (p = 0.001) times more likely to report headaches, 6.1 (p = 0.004) times more likely to report eye irritation, and 7.8 (p = 0.014) times more likely to report nausea in the swine air (experimental) condition than in the control condition. These results indicate that short-term exposure in an environmental chamber to malodorous emissions from a swine house at levels expected downwind can induce clinically important symptoms in healthy human volunteers.