Exposure to structurally unique ß-d-glucans differentially affects inflammatory responses in male mouse lungs.

Pro-inflammatory fungal ß-d-glucan (BDG) polysaccharides cause respiratory pathology. However, specific immunological effects of unique BDG structures on pulmonary inflammation are understudied. We characterized the effect of four unique fungal BDGs with unique branching patterns, solubility, and molecular weights in murine airways. Scleroglucan (1 → 3)(1 → 6)-highly branched BDG, laminarin (1 → 3)(1 → 6)-branched BDG, curdlan (1 → 3)-linear BDG, and pustulan (1 → 6)-linear BDG were assessed by nuclear magnetic resonance spectroscopy. Each BDG was tested by inhalation model with C3HeB/FeJ mice and compared to saline-exposed control mice and unexposed sentinels (n = 3-19). Studies were performed ±heat-inactivation (1 h autoclave) to increase BDG solubility. Outcomes included bronchoalveolar lavage (BAL) differential cell counts (macrophages, neutrophils, lymphocytes, eosinophils), cytokines, serum IgE, and IgG2a (multiplex and ELISA). Ex vivo primary cells removed from lungs and plated at monolayer were stimulated (BDG, lipopolysaccharide (LPS), anti-CD3), and cytokines compared to unstimulated cells. Right lung histology was performed. Inhalation of BDGs with distinct branching patterns exhibited varying inflammatory potency and immunogenicity. Lichen-derived (1 → 6)-linear pustulan was the most pro-inflammatory BDG, increasing inflammatory infiltrate (BAL), serum IgE and IgG2a, and cytokine production. Primed lung cells responded to secondary LPS stimulation with a T-cell-specific response to pustulan. Glucan source and solubility should be considered in exposure and toxicological studies.

Innovative compounds to reduce ß-D-glucans, endotoxin, and allergens newly discovered on smartphones.

Background: Eight-four percent of people own smartphones and view them 14 billion times daily, making them potential vectors for environmental hazards such as allergens, ß-D-glucans (BDGs), and endotoxin. Whether these toxins are prevalent and the effectiveness of cleaning solutions targeting these agents on smartphones have not been studied. Objective: We sought to determine (1) whether phones are reservoirs of allergen, endotoxin, and BDGs and (2) if present, whether their levels can be effectively reduced by using specific cleaning methods. Methods: Electrostatic wipes used to wipe the phones of 15 volunteers were tested to determine their allergen, BDG, and endotoxin levels. Cleaning interventions were done on simulated phone models; 70% isopropyl alcohol, 0.184% benzyl and ethyl benzyl ammonium chloride (Clorox nonbleach [The Chlorox Company, Oakland, Calif]), 0.12% chlorhexidine, 0.05% cetylpyridinium, 3% benzyl benzoate, and 3% tannic acid wipes were used and compared with wipes with no solution (the control). Results: The smartphones showed high and variable levels of BDG and endotoxin. Cat and dog allergens were found mostly on the smartphones of pet owners. The combination of chlorhexidine and cetylpyridinium significantly reduced BDG levels (mean 269 ng/wipe vs 1930 ng/wipe for the control [P < .05]) and endotoxin, (mean 349 vs 1320 endotoxin units/wipe for the control [P < .05]). The combination of benzyl benzoate and tannic acid significantly reduced the levels of cat and dog allergens (dog, mean level of 14 ng/wipe versus 407 ng/wipe for the control [P < .001]; cat, mean level of 55 ng/wipe versus 1550 ng/wipe for the control [P < .001]). The combination mixture solutions had the greatest reductions compared with the control. Conclusions: There are elevated levels of BDG, allergens, and endotoxin on smartphones. The combination of chlorhexidine and cetylpyridinium was the most effective in reducing BDG and endotoxin levels, and the combination of benzyl benzoate and tannic acid was most effective in reducing cat and dog allergen levels on smartphones.

Imaging-based assessment of lung function in a population cooking indoors with biomass fuel: a pilot study.

Biomass fuels (wood) are commonly used indoors in underventilated environments for cooking in the developing world, but the impact on lung physiology is poorly understood. Quantitative computed tomography (qCT) can provide sensitive metrics to compare the lungs of women cooking with wood vs. liquified petroleum gas (LPG). We prospectively assessed (qCT and spirometry) 23 primary female cooks (18 biomass, 5 LPG) with no history of cardiopulmonary disease in Thanjavur, India. CT was obtained at coached total lung capacity (TLC) and residual volume (RV). qCT assessment included texture-derived ground glass opacity [GGO: Adaptive Multiple Feature Method (AMFM)], air-trapping (expiratory voxels ≤ -856HU) and image registration-based assessment [Disease Probability Measure (DPM)] of emphysema, functional small airways disease (%AirTrapDPM), and regional lung mechanics. In addition, within-kitchen exposure assessments included particulate matter <2.5 µm(PM2.5), black carbon, ß-(1, 3)-d-glucan (surrogate for fungi), and endotoxin. Air-trapping went undetected at RV via the threshold-based measure (voxels ≤ -856HU), possibly due to density shifts in the presence of inflammation. However, DPM, utilizing image-matching, demonstrated significant air-trapping in biomass vs. LPG cooks (P = 0.049). A subset of biomass cooks (6/18), identified using k-means clustering, had markedly altered DPM-metrics: greater air-trapping (P < 0.001), lower TLC-RV volume change (P < 0.001), a lower mean anisotropic deformation index (ADI; P < 0.001), and elevated % GGO (P < 0.02). Across all subjects, a texture measure of bronchovascular bundles was correlated to the log-transformed ß-(1, 3)-d-glucan concentration (P = 0.026, R = 0.46), and black carbon (P = 0.04, R = 0.44). This pilot study identified environmental links with qCT-based lung pathologies and a cluster of biomass cooks (33%) with significant small airways disease.NEW & NOTEWORTHY Quantitative computed tomography has identified a cluster of women (33%) cooking with biomass fuels (wood) with image-based markers of functional small airways disease and associated alterations in regional lung mechanics. Texture and image registration-based metrics of lung function may allow for early detection of potential inflammatory processes that may arise in response to inhaled biomass smoke, and help identify phenotypes of chronic lung disease prevalent in nonsmoking women in the developing world.

HEPA filtration intervention in classrooms may improve some students' asthma.

OBJECTIVE: The School Inner-City Asthma Intervention Study 2 (SICAS 2) tested interventions to reduce exposures in classrooms of students with asthma. The objective of this post-hoc analysis was limited to evaluating the effect of high-efficiency particulate (HEPA) filtration interventions on mold levels as quantified using the Environmental Relative Moldiness Index (ERMI) and the possible improvement in the students' asthma, as quantified by spirometry testing. METHODS: Pre-intervention dust samples were collected at the beginning of the school year from classrooms and corresponding homes of students with asthma (n = 150). Follow-up dust samples were collected in the classrooms at the end of the HEPA or Sham intervention. For each dust sample, ERMI values and the Group 1 and Group 2 mold levels (components of the ERMI metric) were quantified. In addition, each student's lung function was evaluated by spirometry testing, specifically the percentage predicted forced expiratory volume at 1 sec (FEV1%), before and at the end of the intervention. RESULTS: For those students with a higher Group 1 mold level in their pre-intervention classroom than home (n = 94), the FEV1% results for those students was significantly (p < 0.05) inversely correlated with the Group 1 level in their classrooms. After the HEPA intervention, the average Group 1 and ERMI values were significantly lowered, and the average FEV1% test results significantly increased by an average of 4.22% for students in HEPA compared to Sham classrooms. CONCLUSIONS: HEPA intervention in classrooms reduced Group 1 and ERMI values, which corresponded to improvements in the students' FEV1% test results.

Multilevel Risk Factors for Sleep-Disordered Breathing-Related Symptom Burden in an Urban Pediatric Community-Based Sample.

BACKGROUND: Pediatric sleep-disordered breathing (SDB) disproportionately affects children with low socioeconomic status (SES). The multilevel risk factors that drive these associations are not well understood. RESEARCH QUESTION: What are the associations between SDB risk factors, including individual health conditions (obesity, asthma, and allergies), household SES (maternal education), indoor exposures (environmental tobacco smoke [ETS] and pests), and neighborhood characteristics (neighborhood disadvantage), and pediatric SDB symptoms? STUDY DESIGN AND METHODS: Cross-sectional analyses were performed on 303 children (aged 6-12 years) enrolled in the Environmental Assessment of Sleep Youth study from 2018 to 2022. Exposures were determined by caregiver reports, assays of measured settled dust from the child's bedroom, and neighborhood-level Census data (deriving the Childhood Opportunity Index to characterize neighborhood disadvantage). The primary outcome was the SDB-related symptom burden assessed by the OSA-18 questionnaire total score. Using linear regression models, we calculated associations between exposures and SDB-related symptom burden, adjusting for sociodemographic factors, then health conditions, indoor environment, and neighborhood factors. RESULTS: The sample included 303 children (39% Hispanic, Latino, Latina, or Spanish origin; 30% Black or African American; 22% White; and 11% other). Increasing OSA-18 total scores were associated with low household SES after adjustment for demographic factors, and with asthma, allergies, ETS, pests (mouse, cockroach, and rodents), and an indoor environmental index (sum of the presence of pests and ETS; 0-2) after adjusting for sociodemographic factors. Even after further adjusting for asthma, allergies, and neighborhood disadvantage, ETS and pest exposure were associated with OSA-18 (ETS: ß = 12.80; 95% CI, 7.07-18.53, also adjusted for pest; pest exposure: ß = 3.69; 95% CI, 0.44-6.94, also adjusted for ETS). INTERPRETATION: In addition to associations with ETS, a novel association was observed for indoor pest exposure and SDB symptom burden. Strategies to reduce household exposure to ETS and indoor allergens should be tested as approaches for reducing sleep health disparities.

Characterization of sub-pollen particles in size-resolved atmospheric aerosol using chemical tracers.

Pollen grains may contain allergens that exacerbate allergic respiratory diseases like asthma and rhinitis. In the presence of water, pollen grains (10-100 µm) can rupture to produce sub-pollen particles (SPP) with diameters <2.5 µm, which in comparison to intact pollen grains, have longer atmospheric lifetimes and greater penetration to the lower lung. The current study examines SPP, fungal spores, and bacteria in size-resolved atmospheric particulate matter (PM) using chemical and biological tracers. During springtime tree pollen season in Iowa City, Iowa, fine particle (PM2.5) concentrations of fructose (a pollen chemical tracer) increased on rainy sampling periods, especially during severe thunderstorms, and peaked when a tornado struck nearby. Submicron fluorescent particles, measured by single-particle fluorescence spectroscopy, were also enhanced during rain events, particularly thunderstorms in agreement with the chemical tracer measurements. PM2.5 sucrose (a pollen chemical tracer) concentrations were higher in early spring when nighttime temperatures were closer to freezing, while fructose concentrations were higher in late spring with warmer temperatures, consistent with chemical tracers being sensitive to seasonal temperature influences. The first co-located measurements of fructose and Bet v 1 (birch pollen allergen), indicated that SPP ranged in diameter from <0.25 to 2.5 µm during rainy sampling periods and that allergens and carbohydrates exhibited distinct size distributions. Meanwhile, mannitol (a fungal spore tracer) peaked on warm, dry days following rain and was primarily in supermicron particles (>1.0 µm), which is consistent with intact fungal spore diameters (1-30 µm). Bacterial endotoxins in PM also increased during extreme weather events, primarily in supermicron particles. While the concentrations of fructose, mannitol, and endotoxin all increased in PM2.5 µm during thunderstorms, the greatest relative increase in concentration was observed for fructose. Together, these observations suggest that SPP containing starch granules and allergens (Bet v 1) were released during rainy sampling periods. This study advances the use of chemical tracers to track SPP and other bioaerosols in the atmosphere, by providing new insight to their size distribution and response to extreme weather conditions.

Cerium Oxide Enhances the Toxicity of Zinc Oxide Nanoparticles in Human Lung Epithelial Cell Cultures.

Recently, many approaches have been developed to improve the performance of nanomaterials. Combining more than one nanomaterial is one such approach that achieves superior results. However, during the fabrication of nanomaterials or formulation of end products, materials can be released into the ambient air and be inhaled by workers. The adverse health outcomes of inhaling such compounds are unknown. In this study, we examined such effects in combining two of the most utilized nanomaterials in several industrial sectors: zinc oxide (ZnO) and cerium oxide (CeO2). These materials can be found together in sunscreens, polyvinyl alcohol (PVA) films, and construction products. The aim of this study was to assess the adverse biological outcomes of CeO2-ZnO nano-mixtures in human lung epithelial cells. A549 human lung epithelial cells were treated with increasing concentrations of ZnO or CeO2 NPs alone, or as a mixture of both, under submerged conditions for 24 h. After treatment, cell viability, reactive oxygen species (ROS) formation, cell membrane integrity, and cytokine production were examined. ZnO NPs showed a dose-dependent trend for all endpoints. CeO2 NPs did not exhibit any toxic effect in any individual concentrations. When higher doses of ZnO were combined with increasing doses of CeO2, loss of cell viability and an elevation in cell membrane leakage were observed. Interleukin 8 (IL-8) and ROS generation were higher when ZnO NPs were combined with CeO2 NPs, compared to cells that were treated with ZnO alone. The release of monocyte chemoattractant protein-1 (MCP-1) was reduced in the cells that were treated with higher doses of ZnO and CeO2. Thus, the presence of CeO2 enhanced the toxicity of ZnO in A549 cells at non-toxic levels of CeO2. This suggests an additive toxicity of these two nanomaterials.

Effect of School Integrated Pest Management or Classroom Air Filter Purifiers on Asthma Symptoms in Students With Active Asthma: A Randomized Clinical Trial.

Importance: School and classroom allergens and particles are associated with asthma morbidity, but the benefit of environmental remediation is not known. Objective: To determine whether use of a school-wide integrated pest management (IPM) program or high-efficiency particulate air (HEPA) filter purifiers in the classrooms improve asthma symptoms in students with active asthma. Design, Setting, and Participants: Factorial randomized clinical trial of a school-wide IPM program and HEPA filter purifiers in the classrooms was conducted from 2015 to 2020 (School Inner-City Asthma Intervention Study). There were 236 students with active asthma attending 41 participating urban elementary schools located in the Northeastern US who were randomized to IPM by school and HEPA filter purifiers by classroom. The date of final follow-up was June 20, 2020. Interventions: The school-wide IPM program consisted of application of rodenticide, sealing entry points, trap placement, targeted cleaning, and brief educational handouts for school staff. Infestation was assessed every 3 months, with additional treatments as needed. Control schools received no IPM, cleaning, or education. Classroom portable HEPA filter purifiers were deployed and the filters were changed every 3 months. Control classrooms received sham HEPA filters that looked and sounded like active HEPA filter purifiers. Randomization was done independently (split-plot design), with matching by the number of enrolled students to ensure a nearly exact 1:1 student ratio for each intervention with 118 students randomized to each group. Participants, investigators, and those assessing outcomes were blinded to the interventions. Main Outcomes and Measures: The primary outcome was the number of symptom-days with asthma during a 2-week period. Symptom-days were assessed every 2 months during the 10 months after randomization. Results: Among the 236 students who were randomized (mean age, 8.1 [SD, 2.0] years; 113 [48%] female), all completed the trial. At baseline, the 2-week mean was 2.2 (SD, 3.9) symptom-days with asthma and 98% of the classrooms had detectable levels of mouse allergen. The results were pooled because there was no statistically significant difference between the 2 interventions (P = .18 for interaction). During a 2-week period, the mean was 1.5 symptom-days with asthma after use of the school-wide IPM program vs 1.9 symptom-days after no IPM across the school year (incidence rate ratio, 0.71 [95% CI, 0.38-1.33]), which was not statistically significantly different. During a 2-week period, the mean was 1.6 symptom-days with asthma after use of HEPA filter purifiers in the classrooms vs 1.8 symptom-days after use of sham HEPA filter purifiers across the school year (incidence rate ratio, 1.47 [95% CI, 0.79-2.75]), which was not statistically significantly different. There were no intervention-related adverse events. Conclusions and Relevance: Among children with active asthma, use of a school-wide IPM program or classroom HEPA filter purifiers did not significantly reduce symptom-days with asthma. However, interpretation of the study findings may need to consider allergen levels, particle exposures, and asthma symptoms at baseline. Trial Registration: ClinicalTrials.gov Identifier: NCT02291302.

Effectiveness of portable HEPA air cleaners on reducing indoor endotoxin, PM10, and coarse particulate matter in an agricultural cohort of children with asthma: A randomized intervention trial.

We conducted a randomized trial of portable HEPA air cleaners in the homes of children age 6-12 years with asthma in the Yakima Valley, Washington. All families received asthma education while intervention families also received two HEPA cleaners (child's bedroom, living room). We collected 14-day integrated samples of endotoxin in settled dust and PM10 and PM10-2.5 in the air of the children's bedrooms at baseline and one-year follow-up, and used linear regression to compare follow-up levels, adjusting for baseline. Seventy-one families (36 HEPA, 35 control) completed the study. Baseline geometric mean (GSD) endotoxin loadings were 1565 (6.3) EU/m2 and 2110 (4.9) EU/m2 , respectively, in HEPA vs. control homes while PM10 and PM10-2.5 were 22.5 (1.9) µg/m3 and 9.5 (2.9) µg/m3 , respectively, in HEPA homes, and 19.8 (1.8) µg/m3 and 7.7 (2.0) µg/m3 , respectively, in control homes. At follow-up, HEPA families had 46% lower (95% CI, 31%-57%) PM10 on average than control families, consistent with prior studies. In the best-fit heterogeneous slopes model, HEPA families had 49% (95% CI, 6%-110%) and 89% lower (95% CI, 28%-177%) PM10-2.5 at follow-up, respectively, at 50th and 75th percentile baseline concentrations. Endotoxin loadings did not differ significantly at follow-up (4% lower, HEPA homes; 95% CI, -87% to 50%).

Lung function of primary cooks using LPG or biomass and the effect of particulate matter on airway epithelial barrier integrity.

BACKGROUND: Cooks exposed to biomass fuel experience increased risk of respiratory disease and mortality. We sought to characterize lung function and environmental exposures of primary cooking women using two fuel-types in southeastern India, as well as to investigate the effect of particulate matter (PM) from kitchens on human airway epithelial (HAE) cells in vitro. METHODS: We assessed pre- and post-bronchodilator lung function on 25 primary female cooks using wood biomass or liquified petroleum gas (LPG), and quantified exposures from 34 kitchens (PM2.5, PM < 40 µm, black carbon, endotoxin, and PM metal and bacterial content). We then challenged HAE cells with PM, assessing its cytotoxicity to small-airway cells (A549) and its effect on: transepithelial conductance and macromolecule permeability (NuLi cells), and antimicrobial activity (using airway surface liquid, ASL, from primary HAE cells). RESULTS: Lung function was impaired in cooks using both fuel-types. 60% of participants in both fuel-types had respiratory restriction (post bronchodilator FEV1/FVC>90). The remaining 40% in the LPG group had normal spirometry (post FEV1/FVC = 80-90), while only 10% of participants in the biomass group had normal spirometry, and the remaining biomass cooks (30%) had respiratory obstruction (post FEV1/FVC<80). Significant differences were found in environmental parameters, with biomass kitchens containing greater PM2.5, black carbon, zirconium, arsenic, iron, vanadium, and endotoxin concentrations. LPG kitchens tended to have more bacteria (p = 0.14), and LPG kitchen PM had greater sulphur concentrations (p = 0.02). In vitro, PM induced cytotoxicity in HAE A549 cells in a dose-dependent manner, however the effect was minimal and there were no differences between fuel-types. PM from homes of participants with a restrictive physiology increased electrical conductance of NuLi HAE cells (p = 0.06) and decreased macromolar permeability (p ≤ 0.05), while PM from homes of those with respiratory obstruction tended to increase electrical conductance (p = 0.20) and permeability (p = 0.07). PM from homes of participants with normal spirometry did not affect conductance or permeability. PM from all homes tended to inhibit antimicrobial activity of primary HAE cell airway surface liquid (p = 0.06). CONCLUSIONS: Biomass cooks had airway obstruction, and significantly greater concentrations of kitchen environmental contaminants than LPG kitchens. PM from homes of participants with respiratory restriction and obstruction altered airway cell barrier function, elucidating mechanisms potentially responsible for respiratory phenotypes observed in biomass cooks.

The home air in agriculture pediatric intervention (HAPI) trial: Rationale and methods.

BACKGROUND: Data addressing air quality effects on children with asthma in rural U.S. communities are rare. Our community engaged research partnership previously demonstrated associations between neighborhood NH3 and ambient PM2.5 and asthma in the agricultural lower Yakima Valley of Washington. As a next step, the partnership desired an intervention approach to address concerns about pediatric asthma in this largely Latino immigrant, farm worker community. OBJECTIVE: The Home Air in Agriculture Pediatric Intervention (HAPI) sought to examine the effectiveness of enrichment of an existing asthma education program with portable high-efficiency particulate air (HEPA) cleaners designed to reduce PM2.5 and NH3. We investigated the effect of this enriched approach on these exposures and asthma health measures. DESIGN: We randomized children with poorly controlled asthma to a control arm (current asthma education program) or an intervention arm (current asthma education program + placement of two indoor air cleaners in the family's home). Outcomes included (1) 14-day integrated samples of indoor air contaminants (PM2.5 and NH3) at baseline and one-year follow-up and (2) child asthma health metrics at baseline, midpoint (4-6 months) and one-year follow-up. These included the Asthma Control Test, symptoms days, clinical utilization, oral corticosteroid use, pulmonary function, fractional exhaled nitric oxide, and urinary leukotriene E4 concentration. DISCUSSION: To our knowledge, this is the first randomized HEPA cleaner intervention designed to assess NH3 as well as PM2.5 and to evaluate health outcomes of children with asthma in an agricultural region.

Characterization of inhalable endotoxin, glucan, and dust exposures in Iowa farmers.

BACKGROUND: The observed deficit of lung cancer in farmers has been partly attributed to exposure to organic dusts and endotoxins based largely on surrogate metrics. To move beyond these surrogates for etiological studies, we characterized task-based and time-weighted average (TWA) exposure to inhalable endotoxin, (1 â†’ 3)-ß-D-glucan, and dust in Iowa farmers. METHODS: We collected 320 personal inhalable dust samples from 32 farmers during 69 sample days in 2015 and 2016. Samples were collected using Button aerosol samplers and analyzed for endotoxin using a kinetic chromogenic amebocyte lysate assay, and for (1 â†’ 3)-ß-D-glucan using a Limulus endpoint assay. We assessed relationships between bioaerosol concentrations and selected tasks and farm characteristics using linear mixed-effects models. RESULTS: Bedding work, hog handling, and working in barn/confinement buildings, grain bins, and grain elevators were associated with higher endotoxin exposure. We found a monotonic trend between higher endotoxin concentrations and increasing number of animals. Bedding work, cleaning, and feed/grain storage work were associated with higher (1 â†’ 3)-ß-D-glucan concentrations. The median concentrations by task spanned one order of magnitude for inhalable dust and two orders of magnitude for endotoxin and (1 â†’ 3)-ß-D-glucan. Pearson correlations between endotoxin and glucan concentrations were 0.22 for TWA exposure and 0.56 for task samples. CONCLUSIONS: This characterization of exposure factors that influence bioaerosol concentrations can support the development of refined bioaerosol exposure metrics for future etiologic analyses of cancer and other health outcomes in farmers.

Inhalable and Respirable Particulate and Endotoxin Exposures in Kentucky Equine Farms.

Adverse respiratory health effects in the agricultural industry have been linked to particulate endotoxin exposure. However, whether the endotoxin concentration is significantly correlated to the size of the particle remains an open question. To date, limited research has been conducted to assess particulate endotoxin exposures in the agricultural industry in general or the equine industry in particular. A task-based exposure assessment was conducted to characterize the endotoxin levels of inhalable and respirable particles on four Kentucky farms during the summer season. We conducted personal sampling of respirable and inhalable particles (n = 75) across all four farms and particulate endotoxin (n = 58) on two of them. Simultaneously, we collected real-time area samples across all four farms by task - horse care, filing hooves, cleaning stalls, cleaning barns, cleaning dry lots, and cleaning trucks. The endotoxin concentration of inhalable particles (geometric mean: 50.2-1,024 EU/m3) was ~50 times higher than that of respirable particles (geometric mean: 1.72-19.0 EU/m3). Horse care generated the lowest endotoxin concentrations for both particle sizes, while cleaning tasks tended to produce higher concentrations. There was no significant correlation between the endotoxin and particle concentrations for each size fraction based on tasks by farm (R2 = 0.069 for inhalable; 0.214 for respirable). The equine workers in this study were exposed to higher endotoxin concentrations than workers in other industries, such as the swine industry. Providing exposure control guidelines and recommendations to the equine industry is necessary to reduce long-term endotoxin exposure and to prevent adverse respiratory symptoms.

Household endotoxin reduction in the Louisa Environmental Intervention Project for rural childhood asthma.

Endotoxin exacerbates asthma. We designed the Louisa Environmental Intervention Project (LEIP) and assessed its effectiveness in reducing household endotoxin and improving asthma symptoms in rural Iowa children. Asthmatic school children (N = 104 from 89 homes) of Louisa and Keokuk counties in Iowa (aged 5-14 years) were recruited and block-randomized to receive extensive (education + professional cleaning) or educational interventions. Environmental sampling collection and respiratory survey administration were done at baseline and during three follow-up visits. Mixed-model analyses were used to assess the effect of the intervention on endotoxin levels and asthma symptoms in the main analysis and of endotoxin reduction on asthma symptoms in exploratory analysis. In the extensive intervention group, dust endotoxin load was significantly reduced in post-intervention visits. The extensive compared with the educational intervention was associated with significantly decreased dust endotoxin load in farm homes and less frequent nighttime asthma symptoms. In exploratory analysis, dust endotoxin load reduction from baseline was associated with lower total asthma symptoms score (Odds ratio: 0.52, 95% confidence interval: 0.29-0.92). In conclusion, the LEIP intervention reduced household dust endotoxin and improved asthma symptoms. However, endotoxin reductions were not sustained post-intervention by residents.

Recirculating Immunocompetent Cells in Colitic Mice Intensify Their Lung Response to Bacterial Endotoxin.

BACKGROUND: Patients with inflammatory bowel disease have higher incidence of airway hyperresponsiveness compared to the general population. Lung inflammation leading to airway hyperresponsiveness causes illnesses for more than ten percent of the population in USA. AIMS: We investigated the lung response to bacterial endotoxin in colitic mice. METHODS: Rag-1 mice were transplanted with negatively selected splenic T cells. Some mice groups were treated with NSAID to develop colitis. All mice were treated with bacterial endotoxin and necropsied 3 weeks later. RESULTS: Colitic mice developed intensified lung inflammation on day 21 of treatment with bacterial endotoxin. Pulmonary lymphocytes from colitic mice displayed a proinflammatory cytokine profile, expressed high ICAM1 and low FoxP3. CD11c+, CD8+ cells bound and responded to non-systemic antigens from gut-localized microbiota and had higher expression of TLR4. CONCLUSIONS: Colitic mice developed exacerbated lung inflammation in response to bacterial endotoxin compared to non-colitic mice. Proinflammatory cytokines from pulmonary lymphocytes induced high expression of ICAM1 and suppressed FoxP3 on CD4+ cells. CD11c+, CD8+ cells binding and responding to gut-localized antigens as well as high expression of TLR4 indicate innate and adaptive lung response to bacterial endotoxin. Inflammatory cells from colons of colitic mice homed in the lungs as well as the intestine suggesting recirculation of sensitized immunocompetent cells. These data support our hypothesis that colitis intensifies lung inflammation.

Atopy as a Modifier of the Relationships Between Endotoxin Exposure and Symptoms Among Laboratory Animal Workers.

BACKGROUND: Exposure to endotoxin is known to trigger airway inflammation and symptoms, and atopy may modify the relationship between endotoxin exposure and symptom development. OBJECTIVE: To test the a priori hypothesis that atopic status modifies the relationship between endotoxin exposure and respiratory symptom development. METHODS: A prospective study of laboratory workers at The Jackson Laboratories was conducted. Allergy skin testing was performed and population demographic and clinical information was obtained at baseline. Personal exposure assessments for airborne endotoxin and surveys of self-reported symptoms were performed every 6 months. Cox proportional hazards models were used to examine the relationship between endotoxin exposure and development of mouse-associated symptoms and multivariate regression was used to test for interaction. RESULTS: Overall, 16 (9%) of 174 worker-participants developed mouse-associated rhinoconjunctivitis symptoms by 24 months and 8 (5%) developed mouse-associated lower respiratory symptoms by 24 months. Among workers with endotoxin exposure above the median (≥2.4 EU m-3), 5 (6% of 80) atopics reported mouse-associated rhinoconjunctivitis symptoms at 24 months as compared to 3 (3% of 94) non-atopics. Among workers below the median endotoxin exposure (<2.4 EU m-3), 1 (1% of 80) atopic reported mouse-associated rhinoconjunctivitis symptoms at 24 months as compared to 7 (7% of 94) non-atopics. For the combination of symptoms, the adjusted hazard ratio was 6.8 (95% confidence interval: 0.7-67.2) for atopics and 0.07 (95% confidence interval: 0.01-0.5) for non-atopics. CONCLUSION: In this occupational cohort, atopic workers may be more susceptible to, and non-atopic workers protected from, endotoxin-associated upper and lower respiratory symptoms.

House Dust Endotoxin Levels Are Associated with Adult Asthma in a U.S. Farming Population.

RATIONALE: Endotoxin initiates a proinflammatory response from the innate immune system. Studies in children suggest that endotoxin exposure from house dust may be an important risk factor for asthma, but few studies have been conducted in adult populations. OBJECTIVES: To investigate the association of house dust endotoxin levels with asthma and related phenotypes (wheeze, atopy, and pulmonary function) in a large U.S. farming population. METHODS: Dust was collected from the bedrooms (n = 2,485) of participants enrolled in a case-control study of current asthma (927 cases) nested within the Agricultural Health Study. Dust endotoxin was measured by Limulus amebocyte lysate assay. Outcomes were measured by questionnaire, spirometry, and blood draw. We evaluated associations using linear and logistic regression. MEASUREMENTS AND MAIN RESULTS: Endotoxin was significantly associated with current asthma (odds ratio [OR], 1.30; 95% confidence interval [CI], 1.14-1.47), and this relationship was modified by early-life farm exposure (born on a farm: OR, 1.18; 95% CI, 1.02-1.37; not born on a farm: OR, 1.67; 95% CI, 1.26-2.20; Interaction P = 0.05). Significant positive associations were seen with both atopic and nonatopic asthma. Endotoxin was not related to either atopy or wheeze. Higher endotoxin was related to lower FEV1/FVC in asthma cases only (Interaction P = 0.01). For asthma, there was suggestive evidence of a gene-by-environment interaction for the CD14 variant rs2569190 (Interaction P = 0.16) but not for the TLR4 variants rs4986790 and rs4986791. CONCLUSIONS: House dust endotoxin was associated with current atopic and nonatopic asthma in a U.S. farming population. The degree of the association with asthma depended on early-life farm exposures. Furthermore, endotoxin was associated with lower pulmonary function in patients with asthma.

Urban Enhancement of PM10 Bioaerosol Tracers Relative to Background Locations in the Midwestern United States.

Bioaerosols are well-known immune-active particles that exacerbate respiratory diseases. Human exposures to bioaerosols and their resultant health impacts depend on their ambient concentrations, seasonal and spatial variation, and co-pollutants, which are not yet widely characterized. In this study, chemical and biological tracers of bioaerosols were quantified in respirable particulate matter (PM10) collected at three urban and three background sites in the Midwestern United States across four seasons in 2012. Endotoxins from gram negative bacteria (and a few gram positive bacteria), water-soluble proteins, and tracers for fungal spores (fungal glucans, arabitol and mannitol) were ubiquitous and showed significant seasonal variation and dependence on temperature. Fungal spores were elevated in spring and peaked in summer, following the seasonal growing cycle, while endotoxins peaked in autumn during the row crop harvesting season. Paired comparisons of bioaerosols in urban and background sites revealed significant urban enhancements in PM10, fungal glucans, endotoxins and water-soluble proteins relative to background locations, such that urban populations have a greater outdoor exposure to bioaerosols. These bioaerosols contribute, in part, to the urban excesses in PM10. Higher bioaerosol mass fractions in urban areas relative to background sites indicate that urban areas serve as a source of bioaerosols. Similar urban enhancements in water-soluble calcium and its correlation with bioaerosol tracers point towards wind-blown soil as an important source of bioaerosols in urban areas.

Innate Immunity and Asthma Risk in Amish and Hutterite Farm Children.

BACKGROUND: The Amish and Hutterites are U.S. agricultural populations whose lifestyles are remarkably similar in many respects but whose farming practices, in particular, are distinct; the former follow traditional farming practices whereas the latter use industrialized farming practices. The populations also show striking disparities in the prevalence of asthma, and little is known about the immune responses underlying these disparities. METHODS: We studied environmental exposures, genetic ancestry, and immune profiles among 60 Amish and Hutterite children, measuring levels of allergens and endotoxins and assessing the microbiome composition of indoor dust samples. Whole blood was collected to measure serum IgE levels, cytokine responses, and gene expression, and peripheral-blood leukocytes were phenotyped with flow cytometry. The effects of dust extracts obtained from Amish and Hutterite homes on immune and airway responses were assessed in a murine model of experimental allergic asthma. RESULTS: Despite the similar genetic ancestries and lifestyles of Amish and Hutterite children, the prevalence of asthma and allergic sensitization was 4 and 6 times as low in the Amish, whereas median endotoxin levels in Amish house dust was 6.8 times as high. Differences in microbial composition were also observed in dust samples from Amish and Hutterite homes. Profound differences in the proportions, phenotypes, and functions of innate immune cells were also found between the two groups of children. In a mouse model of experimental allergic asthma, the intranasal instillation of dust extracts from Amish but not Hutterite homes significantly inhibited airway hyperreactivity and eosinophilia. These protective effects were abrogated in mice that were deficient in MyD88 and Trif, molecules that are critical in innate immune signaling. CONCLUSIONS: The results of our studies in humans and mice indicate that the Amish environment provides protection against asthma by engaging and shaping the innate immune response. (Funded by the National Institutes of Health and others.).