Pharmacological inhibition of GSK-3 in a guinea pig model of LPS-induced pulmonary inflammation: II. Effects on skeletal muscle atrophy

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is accompanied by pulmonary inflammation and associated with extra-pulmonary manifestations, including skeletal muscle atrophy. Glycogen synthase kinase-3 (GSK-3) has been implicated in the regulation of muscle protein- and myonuclear turnover; two crucial processes that determine muscle mass. In the present study we investigated the effect of the selective GSK-3 inhibitor SB216763 on muscle mass in a guinea pig model of lipopolysaccharide (LPS)-induced pulmonary inflammation-associated muscle atrophy.

METHODS

Guinea pigs were pretreated with either intranasally instilled SB216763 or corresponding vehicle prior to each LPS/saline challenge twice weekly. Pulmonary inflammation was confirmed and indices of muscle mass were determined after 12 weeks. Additionally, cultured skeletal muscle cells were incubated with tumor necrosis factor α (TNF-α) or glucocorticoids (GCs) to model the systemic effects of pulmonary inflammation on myogenesis, in the presence or absence of GSK-3 inhibitors.

RESULTS

Repeated LPS instillation induced muscle atrophy based on muscle weight and muscle fiber cross sectional area. Intriguingly, GSK-3 inhibition using SB216763 prevented the LPS-induced muscle mass decreases and myofiber atrophy. Indices of protein turnover signaling were unaltered in guinea pig muscle. Interestingly, inhibition of myogenesis of cultured muscle cells by TNF-α or synthetic GCs was prevented by GSK-3 inhibitors.

CONCLUSIONS

In a guinea pig model of LPS-induced pulmonary inflammation, GSK-3 inhibition prevents skeletal muscle atrophy without affecting pulmonary inflammation. Resistance to inflammation- or GC-induced impairment of myogenic differentiation, imposed by GSK-3 inhibition, suggests that sustained myogenesis may contribute to muscle mass maintenance despite persistent pulmonary inflammation. Collectively, these results warrant further exploration of GSK-3 as a potential novel drug target to prevent or reverse muscle wasting in COPD.

Risk factors for COPD: what do NPs know?

PURPOSE

Chronic obstructive pulmonary disease (COPD) has been identified as the fourth leading cause of death. The primary purpose of this article is to discuss risk factors for COPD and identify at-risk populations. A secondary purpose is to report the findings of a recent survey of nurse practitioners (NPs) in Colorado regarding their knowledge about the risk factors for COPD. Data sources A list of registered NPs in the State of Colorado was obtained from the State Board of Nursing. Surveys were sent to 2916 NPs to assess their knowledge about risk factors for COPD.

CONCLUSIONS

Although the response rate was less than 10%, this survey highlighted that there were gaps in knowledge especially for pediatric, women's health, and geriatric NPs. NPs are on the front lines in assisting with the prevention, early diagnosis, and management of this complex disease.

IMPLICATIONS FOR PRACTICE

Formal NP educational programs (regardless of focus) should highlight that through recognition of risk factors, NPs can play a significant role in primary and secondary preventive measures that may decrease the impact of COPD. Public media campaigns to educate the public about risk factors may encourage the individual patients to address these risk factors with the primary care provider.

Pharmacological inhibition of GSK-3 in a guinea pig model of LPS-induced pulmonary inflammation: I. Effects on lung remodeling and pathology

Background

Glycogen synthase kinase-3 (GSK-3) is a constitutively active kinase that regulates multiple signalling proteins and transcription factors involved in a myriad of cellular processes. The kinase acts as a negative regulator in β-catenin signalling and is critically involved in the smad pathway. Activation of both pathways may contribute to pulmonary features of chronic obstructive pulmonary disease (COPD).

Methods

In the present study, we investigated the effect of the selective GSK-3 inhibitor SB216763 on pulmonary pathology in a guinea pig model of lipopolysaccharide (LPS)-induced COPD. Guinea pigs were instilled intranasally with LPS or saline twice weekly for 12 weeks and pre-treated with either intranasally instilled SB216763 or corresponding vehicle 30 min prior to each LPS/saline challenge.

Results

Repeated LPS exposures activated β-catenin signalling, primarily in the airway epithelium and submucosa. LPS also induced pulmonary inflammation and tissue remodelling as indicated by inflammatory cell influx, increased pulmonary fibronectin expression and enhanced small airway collagen content. Inhibition of GSK-3 by SB216763 did not affect LPS-induced inflammatory cell influx, but prevented the small airway remodelling and, unexpectedly, inhibited the activation of β-catenin in vivo. LPS or SB216763 treatment had no effect on the airway smooth muscle content and alveolar airspace size. However, GSK-3 inhibition prevented LPS-induced right ventricle hypertrophy.

Conclusions

Our findings indicate that GSK-3 inhibition prevents LPS-induced pulmonary pathology in guinea pigs, and that locally reduced LPS-induced β-catenin activation appears in part to underlie this effect.

Air pollution from livestock farms, and asthma, allergic rhinitis and COPD among neighbouring residents

OBJECTIVES

There is an ongoing debate regarding environmental health risks of exposures to dust and microbial agents from livestock farming in the Netherlands. The aims of the study were (1) to investigate associations between indicators of air pollution from livestock farms and asthma, allergic rhinitis and chronic obstructive pulmonary disease (COPD) among neighbouring residents; and (2) to assess associations between farm exposures and endotoxin levels in participants' homes.

METHODS

Electronic medical records of all 92 548 patients of 27 general practices in a rural area with a high density of animal farms were analysed, followed up by a case-control component using a subsample of the full population. Distance between livestock farms and home address, presence of livestock within 500 m, and particulate matter (PM)10 emissions from farms within 500 m were computed as proxies for farm exposure. Potential confounding was investigated through a case-control questionnaire study in 269 adult patients with asthma and 546 controls. Endotoxin levels were assessed in 493 homes.

RESULTS

Modelled PM10 emission was inversely associated with asthma, allergic rhinitis and COPD (p<0.05). A smaller distance to the nearest farm, and the presence of swine, goat and sheep farms were also inversely related to respiratory morbidity, whereas mink farms showed positive associations with asthma and allergic rhinitis. Adjustment for confounding in the case-control study did not change results. Farm exposures were not associated with endotoxin levels in neighbouring residents' homes.

CONCLUSIONS

In conclusion, indicators of air pollution from livestock farms were inversely associated with respiratory morbidity among neighbouring residents.

Occupational health outcomes for workers in the agriculture, forestry and fishing sector: implications for immigrant workers in the southeastern US

BACKGROUND

Workers in the Agriculture, Forestry, and Fisheries (AgFF) sector experience exposures directly related to the work itself, as well as the physical environment in which the work occurs. Health outcomes vary from immediate to delayed, and from acute to chronic.

METHODS

We reviewed existing literature on the health outcomes of work in the AgFF sector and identified areas where further research is needed to understand the impact of these exposures on immigrant Latino workers in the southeastern US.

RESULTS

Outcomes related to specific body systems (e.g., musculoskeletal, respiratory) as well as particular exposure sources (e.g., pesticides, noise) were reviewed. The most extensive evidence exists for agriculture, with a particular focus on chemical exposures. Little research in the southeastern US has examined health outcomes of exposures of immigrant workers in forestry or fisheries.

CONCLUSION

As the AgFF labor force includes a growing number of Latino immigrants, more research is needed to characterize a broad range of exposures and health outcomes experienced by this population, particularly in forestry and fisheries.

Agricultural exposures and chronic bronchitis: findings from the AGRICAN (AGRIculture and CANcer) cohort

PURPOSE

Livestock farming has been recognized as a risk factor for chronic bronchitis (CB). The role of crop farming, however, has been less studied. We sought to assess the role of a large range of farming activities on the risk of CB in the French agricultural cohort AGRICAN (AGRIculture and CANcer).

METHODS

Data on respiratory health and farming activities were collected by questionnaire from 2005 to 2007. Associations between farming activities and self-reported doctor's diagnosis of CB were estimated by a logistic regression adjusted for confounders.

RESULTS

CB was reported by 1207 farmers (8.4%). Two farming activities were associated with CB: cattle raising (odds ratio [OR] 1.24, 95% confidence interval 1.03-1.48), and potato production (OR 1.33, 95% confidence interval 1.13-1.57). Associations were more pronounced in small-scale cattle raising and in large-scale potato production, in particular among the longest exposed workers (≥20 years). Pesticide poisoning and exposure to pesticides in potato farmers were significantly associated with CB risk (OR 1.64 and OR 1.63, respectively).

CONCLUSIONS

This analysis suggests that other agricultural settings not previously reported, such as potato production, may be a risk factor for CB. The nature and circumstances of exposure to hazardous agents need to be further explored.

Evaluation of pulmonary function within a cohort of flavorings workers

OBJECTIVES

We present a re-analysis of a recent Health Hazard Evaluation (HHE) that was performed by the US National Institute for Occupational Safety and Health (NIOSH) regarding the pulmonary status of workers at a flavorings manufacturing facility. This facility has used acetaldehyde, acetoin, benzaldehyde, butyric acid, diacetyl and many other flavoring chemicals for many years.

METHODS

Ten years of spirometry testing and job descriptions data on 112 workers were analyzed by the authors and by NIOSH. Using NIOSH's exposure assessment criteria, we compared the prevalence of restrictive findings (as determined by spirometry testing) in production workers to an internal control group that had reduced or no potential for exposure to flavoring chemicals. NIOSH used multiple linear regression to evaluate changes in pulmonary function by the exposure group. After our review of the NIOSH findings, we evaluated associations between longitudinal changes in pulmonary health and workplace exposures through the use of generalized estimating equations. We then compared our results to those obtained by NIOSH.

RESULTS

We found that the prevalence of pulmonary restriction was similar in production workers and internal controls. We found no relationship between the magnitude of exposure to flavorings chemicals and observed decrements in pulmonary function. Our findings were contrary to those reported by NIOSH, most likely because of how we accounted for the longitudinal nature of the spirometric data.

CONCLUSION

Many years of exposures to flavoring chemicals in this workplace, including diacetyl, were not found to produce an increased risk of abnormal spirometric findings.

Exposure to inhalable dust and endotoxin among Danish pig farmers affected by work tasks and stable characteristics

OBJECTIVE

To identify working tasks and stable characteristics that determine intensity and variability of personal exposure to dust and endotoxin among pig farmers.

METHODS

Three hundred fifty-four personal full-shift measurements were performed in 231 farmers employed in 53 Danish pig farms. Filters were gravimetrically analysed for inhalable dust and for endotoxin by the Limulus amebocyte lysate assay. Information on working tasks and stable characteristics were collected using self-reported activity diaries and walk-through surveys performed in conjunction with the measurements. Associations between log-transformed dust and endotoxin exposure and working tasks and stable characteristics were examined using linear mixed-effects analysis. In these models, worker and farm identity were treated as random effects and working tasks and stable characteristics as fixed effects. Both separate and combined models for tasks and stable characteristics were elaborated.

RESULTS

Inhalable dust concentrations ranged between 0.1 and 48 mg m(-3) and endotoxin concentrations varied between 9.2 and 370,000 EU m(-3). Field work activities played a dominant role on the exposure variability. Indoor working tasks with intense animal activity or handling of feed materials increased exposure concentrations, whereas engagement in field work was associated with lower exposure concentrations. High-pressure water cleaning increased endotoxin exposure but did not affect exposure to inhalable dust. Stable characteristics related to feeding practices and type of ventilation were determinants of exposure to inhalable dust. For endotoxin, the most important determinants were use of dry feed and slatted floor coverage. Feeding practices solely explained all between-farms variability in exposure to inhalable dust and endotoxin.

CONCLUSIONS

These findings suggest feeding systems, flooring and ventilation to be potential areas where improved methods can reduce exposure to dust and endotoxin among pig farmers. Further, they highlight particular tasks involving feeding and intense animal handling as sources of very high levels of exposure. The pig farming industry is encouraged to focus on exposure reduction. Use of respirators during performance of working tasks where levels of exposure are particularly high ought to be considered until adequate hygienic solutions have been established.

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.

Occupational chronic obstructive pulmonary disease: an update

Chronic obstructive pulmonary disease represents a major cause of morbidity and mortality in industrialized and nonindustrialized countries. Although tobacco use remains the main factor associated with development of the disease, occupational risk factors represent an important and preventable cause. The most common occupationally related factors include exposure to organic dusts, metallic fumes, and a variety of other mineral gases and/or vapors. This article summarizes the literature on the subject and provides an update of the most recent advances in the field.

Association of Toll-like receptor 2 gene polymorphisms with lung function in workers in swine operations

BACKGROUND

Workers in swine operations are exposed to indoor dusts and gases and are at increased risk of respiratory problems. Toll-like receptor (TLR) 2 recognizes ligands from gram-positive bacteria, whereas TLR4 responds to endotoxin from gram-negative bacteria.

OBJECTIVE

To investigate the effects of TLR2 and TLR4 polymorphisms on lung function in workers from swine operations and nonfarming rural dwellers.

METHODS

A total of 374 full-time workers from large swine operations and 411 nonfarming rural dwellers from Saskatchewan were included. Information on demography, lifestyle, and occupation, lung function measurements, and blood samples for genotyping were obtained from the participants. Multiple regression analysis and Bonferroni correction were used in the statistical analysis.

RESULTS

Workers with TLR2-16933T/A polymorphism (AA) had significantly greater mean values of lung function than workers with wild-type genotypes (AT+TT) after controlling for potential confounders (forced expiratory volume in 1 second, 3.7 vs 3.5 L; P=.009; forced expiratory flow between 25% and 75%, 3.7 vs 3.3 L; P=.003; predicted forced expiratory volume in 1 second; 100.3% vs 95.6%; P=.005; forced expiratory flow between 25% and 75%, 92.4% vs 83.4%; P=.009). These results were also observed for TLR2Arg677Trp polymorphism among the workers. No such significant differences were observed among nonfarming rural dwellers. For Asp299Gly and Thr399Ile polymorphisms in the TLR4 gene, no significant differences were observed in the mean lung function values between the polymorphic and wild-type groups in both workers and rural dwellers.

CONCLUSION

Our study is the first, to our knowledge, to report protective effects of TLR2 polymorphisms on lung function among workers in swine operations and raises the possibility that TLR2 polymorphisms are protective of airway disease in individuals exposed to gram-positive organisms in the inhaled airborne dust.

Microbial exposure and respiratory dysfunction in poultry hatchery workers

Today's modern animal confinement with high stocking density of a single species has resulted in new workplaces that are rarely characterised in regard to microbial exposure. In this study we determine the personal microbial exposure by long term monitoring in a duck hatchery. Four hatchery workers were accompanied for four weeks and on every working day personal bioaerosol sampling and lung function tests were performed. Quantitative and qualitative molecular methods were used for analysing bioaerosol samples. Restriction Fragment Length Polymorphism (RFLP) analyses showed a unique microbial exposure on eclosion days. By 16S rRNA gene sequence cloning analysis we detected Staphylococcus, Acinetobacter and Enterococcus as predominant bacterial genera. Ducklings' down was identified as a medium for bacterial contamination. Furthermore on eclosion days the four workers showed a decline in lung function over their working shift causing an average FEV 1 decrease.

Occupational exposure to particulate matter and respiratory symptoms in Portuguese swine barn workers

Certain environmental conditions in animal and plant production have been associated with increased frequency in respiratory illnesses, including asthma, chronic bronchitis, and hypersensitivity pneumonitis, in farmers occupationally exposed in swine production. The aim of this study was to characterize particulate matter (PM) contamination in seven Portuguese swine farms and determine the existence of clinical symptoms associated with asthma and other allergy diseases, utilizing the European Community Respiratory Health Survey questionnaire. Environmental assessments were performed with portable direct-reading equipment, and PM contamination including five different sizes (PM0.5, PM1.0, PM2.5, PM5.0, PM10) was determined. The distribution of particle size showed the same trend in all swine farms, with high concentrations of particles with PM5 and PM10. Results from the questionnaire indicated a trend such that subjects with diagnosis of asthma were exposed to higher concentrations of PM with larger size (PM2.5, PM5, and PM10) while subjects with sneezing, runny nose, or stuffy nose without a cold or flu were exposed to higher concentrations of PM with smaller size (PM0.5 and PM1). Data indicate that inhalation of PM in swine farm workers is associated with increased frequency of respiratory illnesses.

Pulmonary function reductions among potentially susceptible subgroups of agricultural workers in Colorado and Nebraska

OBJECTIVE

Organic dust inhalation has been associated with adverse respiratory responses among agricultural workers. We evaluated factors that may confer increased susceptibility to these health effects.

METHODS

We quantified personal work shift exposures to inhalable dust, endotoxin, and its 3-hydroxy fatty acid constituents, and evaluated changes in pulmonary function among 137 grain elevator, cattle feedlot, dairy, and corn farm workers.

RESULTS

Increased dust exposure was associated with work shift reductions in lung function. Although interpretation is limited because of small samples, a suggestion of stronger exposure-response relationships was observed among smokers, as well as workers reporting pesticide/herbicide application, asthma, or allergies, and those with genetic polymorphisms (TLR4) (Pinteraction ≤ 0.05).

CONCLUSIONS

A better understanding of factors leading to increased susceptibility of adverse respiratory outcomes is needed to optimize exposure reduction strategies and develop more comprehensive wellness programs.

αβ T cells and a mixed Th1/Th17 response are important in organic dust-induced airway disease

BACKGROUND

Organic dust exposure in agricultural environments induces an inflammatory response that attenuates over time, yet repetitive dust exposures result in chronic lung diseases. Animal models resembling this chronic lung inflammatory response have been developed, yet the underlying cellular mechanisms are not well defined.

OBJECTIVE

Because mice repetitively exposed to organic dust extracts (DE) display increased CD3+ T cell lung infiltrates, we sought to determine the phenotype and importance of these cells.

METHODS

Mice received swine confinement DE repetitively for 3 weeks by established intranasal inhalation protocol. Studies were conducted with peptidoglycan (PGN) because it is a major DE component in large animal farming environments and has shared similar biologic effects with DE. Enumeration of T cells and intracellular cytokine profiles were conducted by flow cytometry techniques. Whole lung homogenate cytokines were analyzed by multiplex immunoassay. T cell receptor (TCR) αβ knockouts were used to determine the functional importance of αβ-expressing T cells.

RESULTS

DE increased lung-associated CD3+CD4+ T cells and interleukin (IL)-17 (but not IL-4, interferon [IFN]-γ, IL-10) producing CD4+ T cells. PGN treatment resulted in increased IL-17 and IFN-γ producing CD4+ T cells and IFN-γ producing CD8+ T cells. Both DE and PGN augmented expression of cytokines associated with Th1 and Th17 polarization in lung homogenates. DE-induced lung mononuclear aggregates and bronchiolar compartment inflammation were significantly reduced in TCR knockout animals; however, neutrophil influx and alveolar compartment inflammation were not affected.

CONCLUSION

Studies demonstrated that DE and PGN exposure promote a Th1/Th17 lung microenvironment and that αβ-expressing T cells are important in mediating DE-induced lung pathologic conditions.

CD11c(+)/CD11b(+) cells are critical for organic dust-elicited murine lung inflammation

Organic dust exposure in the agricultural industry results in significant lung disease. Macrophage infiltrates are increased in the lungs after organic dust exposures, yet the phenotype and functional importance of these cells remain unclear. Using an established intranasal inhalation murine model of dust-induced lung inflammation, animals were treated once or daily for 3 weeks with swine confinement organic dust extract (DE). Repetitive DE treatment for 3 weeks resulted in significant increases in CD11c(+)/CD11b(+) macrophages in whole lung-associated tissue. These cells displayed increased costimulatory molecule (CD80 and CD86) expression, enhanced phagocytic ability, and an increased production of IL-6, CXCL1, and CXCL2. Similar findings were observed with the CD11c(+)/CD11b(+) macrophage infiltrate after repetitive exposure to peptidoglycan, a major DE component. To determine the functional importance of macrophages in mediating DE-induced airway inflammation, lung macrophages were selectively depleted using a well-established intranasal clodronate liposome depletion/suicide strategy. First, macrophage depletion by clodronate liposomes resulted in significant reductions in airway neutrophil influx and TNF-α and IL-6 production after a single exposure to DE. In contrast, after repetitive 3-week exposure to DE, airway lavage fluid and lung tissue neutrophils were significantly increased in clodronate liposome-treated mice compared with control mice. A histological examination of lung tissue demonstrated striking increases in alveolar and bronchiolar inflammation, as well as in the size and distribution of cellular aggregates in clodronate-liposome versus saline-liposome groups repetitively exposed to DE. These studies demonstrate that DE elicits activated CD11c(+)/CD11b(+) macrophages in the lung, which play a critical role in regulating the outcome of DE-induced airway inflammation.

Immunological and inflammatory responses to organic dust in agriculture

PURPOSE OF REVIEW

Agriculture represents a major industry worldwide, and despite protection against the development of IgE-mediated diseases, chronic exposure to agriculture-related organic dusts is associated with an increased risk of developing respiratory disease. This article will review the literature regarding new knowledge of important etiologic agents in the dusts and focus on the immunologic responses following acute and repetitive organic dust exposures.

RECENT FINDINGS

Although endotoxin remains important, there is an emerging role of nonendotoxin components such as peptidoglycans from Gram-positive bacteria. Pattern recognition receptors including Toll-like receptor 4 (TLR4), TLR2 and intracellular nucleotide oligomerization domain-like receptors are partially responsible for mediating the inflammatory consequences. Repeated organic dust exposures modulate innate and adaptive immune function with a resultant adaptation-like response. However, repetitive exposures cause lung parenchymal inflammation, chronic disease, and lung function decline over time.

SUMMARY

The immunological consequences of organic dust exposure in the farming industry are likely explained by the diversity of microbial motifs in dust that can elicit differing innate immune receptor signaling pathways. Whereas initial activation results in a robust inflammatory response, repetitive dust exposures modulate immunity. This can result in low-grade, chronic inflammation, and/or protection against allergic disease.

Alcohol exposure alters mouse lung inflammation in response to inhaled dust

Alcohol exposure is associated with increased lung infections and decreased mucociliary clearance. Occupational workers exposed to dusts from concentrated animal feeding operations (CAFOs) are at risk for developing chronic inflammatory lung diseases. Agricultural worker co-exposure to alcohol and organic dust has been established, although little research has been conducted on the combination effects of alcohol and organic dusts on the lung. Previously, we have shown in a mouse model that exposure to hog dust extract (HDE) collected from a CAFO results in the activation of protein kinase C (PKC), elevated lavage fluid cytokines/chemokines including interleukin-6 (IL-6), and the development of significant lung pathology. Because alcohol blocks airway epithelial cell release of IL-6 in vitro, we hypothesized that alcohol exposure would alter mouse lung inflammatory responses to HDE. To test this hypothesis, C57BL/6 mice were fed 20% alcohol or water ad libitum for 6 weeks and treated with 12.5% HDE by intranasal inhalation method daily during the final three weeks. Bronchoalveolar lavage fluid (BALF), tracheas and lungs were collected. HDE stimulated a 2–4 fold increase in lung and tracheal PKCε (epsilon) activity in mice, but no such increase in PKCε activity was observed in dust-exposed mice fed alcohol. Similarly, alcohol-fed mice demonstrated significantly less IL-6 in lung lavage in response to dust than that observed in control mice instilled with HDE. TNFα levels were also inhibited in the alcohol and HDE-exposed mouse lung tissue as compared to the HDE only exposed group. HDE-induced lung inflammatory aggregates clearly present in the tissue from HDE only exposed animals were not visually detectable in the HDE/alcohol co-exposure group. Statistically significant weight reductions and 20% mortality were also observed in the mice co-exposed to HDE and alcohol. These data suggest that alcohol exposure depresses the ability of the lung to activate PKCε-dependent inflammatory pathways to environmental dust exposure. These data also define alcohol as an important co-exposure agent to consider in the study of inhalation injury responses.

Smoking cessation and environmental hygiene

Although there are nonmodifiable genetic risk factors for COPD, most known risk factors for development and progression of COPD can be corrected. Continued efforts to encourage smoking cessation and measures to reduce exposure to SHS, outdoor air pollution, biomass smoke, and occupational and related amateur exposures will have a significant impact on worldwide health.

Daily exposure to dust alters innate immunity

Pig farmers are exposed to organic material in pig barns on a daily basis and have signs of an ongoing chronic airway inflammation and increased prevalence of chronic inflammatory airway diseases, predominantly chronic bronchitis. Interestingly, the inflammatory response to acute exposure to organic dust is attenuated in farmers. The aim of the study was to closer characterize innate immunity features in blood and airways in farmers and in naïve, non-exposed, controls. The expression of pattern recognition receptors (TLR2, TLR4 and CD14) whose ligands are abundant in pig barn dust and adhesion proteins (CD11b, CD62L and CD162L) on blood and sputum neutrophils in pig farmers and soluble TLR2 and CD14 (sTLR2 and sCD14) in blood and sputum were assessed in pig farmers and previously unexposed controls. The release of pro-inflammatory cytokines from blood cells stimulated with LPS ex vivo was measured in the absence and presence of anti-ST2. We also examined, in a separate study population, serum levels of soluble ST2 (sST2), before and after exposure in a pig barn and a bronchial LPS challenge. Farmers had signs of ongoing chronic inflammation with increased number of blood monocytes, and decreased expression of CD62L and CD162 on blood neutrophils. Farmers also had lower levels of sTLR2 and sCD14 in sputum and reduced expression of CD14 on sputum neutrophils than controls. Exposure to organic dust and LPS induced increase of serum sST2 in controls but not in farmers. In conclusion, farmers have signs of local and systemic inflammation associated with altered innate immunity characteristics.

Occupation and chronic obstructive pulmonary disease (COPD)

INTRODUCTION

There is growing interest in preventable, non-smoking causes of chronic obstructive pulmonary disease (COPD), among which are chronic exposures to respiratory irritants in the workplace.

SOURCES OF DATA

Reviews of occupational COPD in specific occupations and industries and in general populations; supplemented with other or more recently published material.

AREAS OF AGREEMENT

There is good evidence for an increased risk of COPD from certain specific exposures (coal mine dust, silica, welding fume, textile dust, agricultural dust, cadmium fume).

AREAS OF CONTROVERSY

Less clear is the causal role of non-specific dusts or fumes/gases in general populations where the available literature is notably uncritical.

GROWING POINTS

Other specific exposures, such as diesel fume; interactions between specific exposures and cigarette smoking; the development of safe working limits.

AREAS TIMELY FOR DEVELOPING RESEARCH

Occupations with large numbers of exposed employees, particularly in low-income countries.

Chronic obstructive pulmonary disease patients have greater systemic responsiveness to ex vivo stimulation with swine dust extract and its components versus healthy volunteers

Chronic obstructive pulmonary disease (COPD) is characterized by an airway and systemic inflammatory response. Bioaerosols/organic dusts are important agricultural pollutants that may lead to COPD. These environments are complex, containing a rich source of various microbial components. The objective of this study was to determine whether individuals with COPD have enhanced systemic responsiveness to settled swine facility organic dust extract (ODE) or its main pathogenic components (peptidoglycan [PGN], lipopolysaccharide [LPS]) versus healthy volunteers. A modified whole blood assay (WBA) that included occupational levels of ODE and concentrations of LPS and PGN found in ODE was used to determine systemic responsiveness (mediator release), and sputum inflammatory markers were measured to explore for systemic and airway associations. Sputum samples were evaluated for cell counts, and tumor necrosis factor (TNF)-α, interleukin (IL)-8/CXCL8, IL-6, and IL-10. Ex vivo whole blood stimulation with ODE, LPS, and PGN each resulted in significant mediator release in all subjects, with the highest occurring with ODE; PGN resulted in significantly enhanced TNF-α and IL-8 as compared to LPS. COPD subjects demonstrated greater systemic responsiveness using the modified WBA versus healthy controls. Within COPD subjects, blood baseline TNF-α, IL-8, and IL-10 and ODE-, PGN-, and LPS-stimulated IL-8 levels significantly correlated with lung function. In conclusion, dust-induced mediator release was robust, and PGN, in part, resembled dust-induced mediator release. Subjects with COPD demonstrated increased mediator release following ex vivo whole blood stimulation with bioaerosol components, suggesting that circulating blood cells in COPD subjects may be primed to respond greater to microbial/inflammatory insult.

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.

Yearly emission factors of ammonia and particulate matter from three laying-hen housing systems

The aim of the present study was to measure the concentration of ammonia and particulate matter (PM) that passes through a size‐selective inlet with a 50% cut‐off at 10-μm aerodynamic-equivalent diameter (PM10) and emissions into atmosphere in the following three types of laying-hen houses: traditional battery cages with aerated open-manure storage (BSP) and two best available technique (BAT) housing types, namely, an aviary-system housing (ASH) and a vertical tiered cage with manure belts and forced-air drying (VTC). Measurements were taken continuously for a period of 1 year in each house. Ammonia concentration was measured continuously in each house using an infrared photoacoustic detector with a 15-min sampling interval. PM10 was measured continuously using a scatter light photometer, corrected by the traditional gravimetric-technique concentration to lower the measurement error. The same instrument was also used to collect PM10 through a traditional gravimetric technique. This procedure was performed to adjust the particulate matter-specific gravity of PM that is typical and specific for every animal house. PM10 and ammonia measurements were carried out together with measurements of inside and outside temperature, inside and outside relative humidity and ventilation rate. For the high PM10 concentrations measured in the ASH house during a preliminary survey, concentrations of total suspended particles (TSP) and fine PM (particles <2.5 microns) were also measured to evaluate the dustiness in the building during the working hours. The ammonia concentration was 5.37 mg/m3 in the traditional BSP house (the reference for cage-housing system), 4.95 mg/m3 in the VTC and 3.85 mg/m3 in the ASH. The ammonia-emission factors were 15.445 mg/h.hen place (0.135 kg/year.hen place) for BSP, 8.258 mg/h.hen place (0.072 kg/year.hen place) for VTC, and 23.704 mg/h.hen place (0.208 kg/year.hen place) for ASH. Ammonia emission-reduction efficiency of VTC v. the BSP was 53%, according to thresholds assessed by Integrated Prevention Pollution Control. The ammonia-reduction efficiency of ASH v. that of the standard Reference Housing system for non-cage housing was 68%. Average yearly PM10 concentration was remarkably higher in the ASH, with 0.215 mg/m3 v. 0.108 mg/m3 for the VTC and 0.094 mg/m3 for BSP. In the ASH, the concentration of total suspended particles (TSP) was 0.444 mg/m3 and that of PM2.5 was 0.032 mg/m3. In this facility, a great variation of PM10 concentration occurred in the morning hours. Recorded values for the PM10 emission were 0.433 mg/h.hen for BSP and 0.081 mg/h.hen for VTC, while the ASH showed the highest PM10 emission (1.230 mg/h.hen), with clear peaks occurring in the morning hours during daily farming operations.

Air pollution, lung function, and physical symptoms in communities near concentrated Swine feeding operations

BACKGROUND

Concentrated animal feeding operations emit air pollutants that may affect health. We examined associations of reported hog odor and of monitored air pollutants with physical symptoms and lung function in people living within 1.5 miles of hog operations.

METHODS

Between September 2003 and September 2005, we measured hydrogen sulfide (H2S), endotoxin, and particulate matter (PM10, PM2.5, and PM2.5-10) for approximately 2-week periods in each of 16 eastern North Carolina communities. During the same time periods, 101 adults sat outside their homes twice a day for 10 minutes, reported hog odor and physical symptoms, and measured their lung function. Conditional fixed-effects logistic and linear regression models were used to derive estimates of associations.

RESULTS

The log odds (±1 standard error) of acute eye irritation following 10 minutes outdoors increased by 0.53 (±0.06) for every unit increase in odor, by 0.15 (±0.06) per 1 ppb of H2S, and by 0.36 (±0.11) per 10 μg/m of PM10. Odor and H2S were also associated with irritation and respiratory symptoms in the previous 12 hours. The log odds of difficulty breathing increased by 0.50 (±0.15) per unit of odor. A 10 μg/m increase in mean 12-hour PM2.5 was associated with increased log odds of wheezing (0.84 ± 0.29) and declines in forced expiratory volume in 1 second (-0.04 ± 0.02 L). A 10 EU/mg increase in endotoxin was associated with increased log odds of sore throat (0.10 ± 0.05), chest tightness (0.09 ± 0.04), and nausea (0.10 ± 0.05).

CONCLUSIONS

Pollutants measured near hog operations are related to acute physical symptoms in a longitudinal study using analyses that preclude confounding by time-invariant characteristics of individuals.

Organic dust augments nucleotide-binding oligomerization domain expression via an NF-{kappa}B pathway to negatively regulate inflammatory responses

Nucleotide-binding oligomerization domain 2 (NOD2) is involved in innate immune responses to peptidoglycan degradation products. Peptidoglycans are important mediators of organic dust-induced airway diseases in exposed agriculture workers; however, the role of NOD2 in response to complex organic dust is unknown. Monocytes/macrophages were exposed to swine facility organic dust extract (ODE), whereupon NOD2 expression was evaluated by real-time PCR and Western blot. ODE induced significant NOD2 mRNA and protein expression at 24 and 48 h, respectively, which was mediated via a NF-κB signaling pathway as opposed to a TNF-α autocrine/paracrine mechanism. Specifically, NF-κB translocation increased rapidly following ODE stimulation as demonstrated by EMSA, and inhibition of the NF-κB pathway significantly reduced ODE-induced NOD2 expression. However, there was no significant reduction in ODE-induced NOD2 gene expression when TNF-α was inhibited or absent. Next, it was determined whether NOD2 regulated ODE-induced inflammatory cytokine production. Knockdown of NOD2 expression by small interfering RNA resulted in increased CXCL8 and IL-6, but not TNF-α production in response to ODE. Similarly, primary lung macrophages from NOD2 knockout mice demonstrated increased IL-6, CXCL1, and CXCL1, but not TNF-α, expression. Lastly, a higher degree of airway inflammation occurred in the absence of NOD2 following acute (single) and repetitive (3 wk) ODE exposure in an established in vivo murine model. In summary, ODE-induced NOD2 expression is directly dependent on NF-κB signaling, and NOD2 is a negative regulator of complex, organic dust-induced inflammatory cytokine/chemokine production in mononuclear phagocytes.

Predictors of airborne endotoxin concentrations in inner city homes

Few studies have assessed in home factors which contribute to airborne endotoxin concentrations. In 85 inner city Baltimore homes, we found no significant correlation between settled dust and airborne endotoxin concentrations. Certain household activities and characteristics, including frequency of dusting, air conditioner use and type of flooring, explained 36-42% of the variability of airborne concentrations. Measurements of both airborne and settled dust endotoxin concentrations may be needed to fully characterize domestic exposure in epidemiologic investigations.

Airway epithelial epidermal growth factor receptor mediates hogbarn dust-induced cytokine release but not Ca2+ response

A subset of workers in swine confinement facilities develops chronic respiratory disease. An aqueous extract of dust from these facilities (hogbarn dust extract [HDE]) induces IL-6 and IL-8 release and several other responses in isolated airway epithelial cells. The cell membrane receptors by which HDE initiates these responses have not been identified. Because several other inhaled agents induce airway epithelial cell responses through epidermal growth factor receptor (EGFR) activation, we hypothesized that HDE would activate EGFRs and that EGFRs would be required for some of the responses to HDE. Exposure of Beas-2B cells to HDE caused EGFR phosphorylation and downstream ERK activation, and both responses were blocked by the EGFR-selective kinase inhibitor AG1478. AG1478 and EGFR-neutralizing antibody reduced HDE-stimulated IL-6 and IL-8 release by about half. Similar EGFR phosphorylation and requirement of EGFRs for maximal IL-6 and IL-8 release were found with primary isolates of human bronchial epithelial cells. Because HDE-stimulated IL-6 and IL-8 release involve the Ca(2+)-dependent protein kinase Cα, we hypothesized that HDE would induce intracellular Ca(2+) mobilization. HDE exposure induced intracellular Ca(2+) mobilization in Beas-2B cells and in primary cell isolates, but this response was neither mimicked by EGF nor inhibited by AG1478. Thus, HDE activates EGFRs and their downstream signaling, and EGFR activation is required for some but not all airway epithelial cell responses to HDE.

[COPD in nonsmokers]

The association of chronic obstructive pulmonary disease (COPD) and smoking is well established. However, an increasing number of studies have reported a not inconsiderable prevalence of COPD among nonsmokers. Therefore, other factors, both endogenous and exogenous, may influence the development of this disease. The present article reviews the influence of possible genetic factors, gender and other respiratory diseases (such as chronic asthma and tuberculosis), as well as environmental pollution and occupational exposure in the development of COPD.

Toll-like receptor 2 regulates organic dust-induced airway inflammation

Organic dust exposure in agricultural environments results in significant airway inflammatory diseases. Gram-positive cell wall components are present in high concentrations in animal farming dusts, but their role in mediating dust-induced airway inflammation is not clear. This study investigated the role of Toll-like receptor (TLR) 2, a pattern recognition receptor for gram-positive cell wall products, in regulating swine facility organic dust extract (DE)-induced airway inflammation in mice. Isolated lung macrophages from TLR2 knockout mice demonstrated reduced TNF-α, IL-6, keratinocyte chemoattractant/CXCL1, but not macrophage inflammatory protein-2/CXCL2 expression, after DE stimulation ex vivo. Next, using an established mouse model of intranasal inhalation challenge, we analyzed bronchoalveolar lavage fluid and lung tissue in TLR2-deficient and wild-type (WT) mice after single and repetitive DE challenge. Neutrophil influx and select cytokines/chemokines were significantly lower in TLR2-deficient mice at 5 and 24 hours after single DE challenge. After daily exposure to DE for 2 weeks, there were significant reductions in total cellularity, neutrophil influx, and TNF-α, IL-6, CXCL1, but not CXCL2 expression, in TLR2-deficient mice as compared with WT animals. Lung pathology revealed that bronchiolar inflammation, but not alveolar inflammation, was reduced in TLR2-deficient mice after repetitive exposure. Airway hyperresponsiveness to methacholine after dust exposure was similar in both groups. Finally, airway inflammatory responses in WT mice after challenge with a TLR2 agonist, peptidoglycan, resembled DE-induced responses. Collectively, these results demonstrate that the TLR2 pathway is important in regulating swine facility organic dust-induced airway inflammation, which suggests the importance of TLR2 agonists in mediating large animal farming-induced airway inflammatory responses.

1H and hyperpolarized 3He magnetic resonance imaging clearly detect the preventative effect of a glucocorticoid on endotoxin-induced pulmonary inflammation in vivo

Introduction: Proton (1H) magnetic resonance imaging (MRI) can be utilized to quantify pulmonary edema in endotoxin-induced pulmonary inflammation and hyperpolarized (HP) 3He MRI can assess pulmonary ventilation. Neither of the methods has been applied to assess the impact of a drug on endotoxin-induced pulmonary inflammation in vivo. The aim of the current study was to evaluate the capability of 1H and HP 3He MRI to assess the effects of a glucocorticoid on endotoxin-induced pulmonary inflammation in vivo.

Materials and Methods: Mice were exposed to an aerosol of either saline or endotoxin (5 mg/ml) for 10 min. Half of the endotoxin-exposed mice were pretreated with a glucocorticoid (budesonide 3 mg/kg; 2 times/day) and the other half with vehicle p.o. The first budesonide treatment was administered 1 h prior to the aerosol inhalation. Forty-eight hours after the aerosol exposure, the mice were anaesthetized for subsequent imaging. Hyperpolarized 3He was administered and axial MR images of the lungs obtained. Matching 1H MR images were then acquired. The mice were sacrificed and broncho-alveolar lavage (BAL) samples were harvested to determine total and cell differential counts. Results: The lesion volume on both 1H and 3He MRI, were markedly increased by endotoxin exposure (P<0.001). Budesonide strongly reduced lesion volume ( P<0.001). The BAL cell count correlated strongly with both 3He ( P<0.001; r = 0.96) and 1H lesion volumes ( P<0.001; r = 0.97).

Conclusions: Hyperpolarized 3He MRI and 1H MRI clearly visualized the preventative effect of budesonide on the impact of endotoxin on pulmonary ventilation and edema, respectively. The fact that ventilation defects on 3He MRI corresponded to findings from conventional 1H MRI, as well as to counts of BAL inflammatory cells suggests that these imaging techniques constitute promising tools for non-invasive monitoring of pulmonary inflammation in vivo.

Chronic obstructive pulmonary disease in non-smokers

Chronic obstructive pulmonary disease (COPD) is a leading cause of morbidity and mortality worldwide. Tobacco smoking is established as a major risk factor, but emerging evidence suggests that other risk factors are important, especially in developing countries. An estimated 25-45% of patients with COPD have never smoked; the burden of non-smoking COPD is therefore much higher than previously believed. About 3 billion people, half the worldwide population, are exposed to smoke from biomass fuel compared with 1.01 billion people who smoke tobacco, which suggests that exposure to biomass smoke might be the biggest risk factor for COPD globally. We review the evidence for the association of COPD with biomass fuel, occupational exposure to dusts and gases, history of pulmonary tuberculosis, chronic asthma, respiratory-tract infections during childhood, outdoor air pollution, and poor socioeconomic status.