Endotoxin exposure in inner-city schools and homes of children with asthma

Pediatric Inner-City Asthma

Inner-city children with asthma are known to have high disease mortality and morbidity. Frequently, asthma in this high-risk population is difficult to control and more severe in nature. Several factors, including socioeconomic hardship, ability to access to health care, adherence to medication, exposure to certain allergens, pollution, crowd environment, stress, and infections, play an important role in the pathophysiology of inner-city asthma. Comprehensive control of home allergens and exposure to tobacco smoke, the use of immune based therapies, and school-based asthma programs have shown promising results in asthma control in this population.

Exposure to indoor air contaminants in school buildings with and without reported indoor air quality problems

Reported indoor air quality (IAQ) complaints are common even in relatively new or renovated school buildings in Finland. However, detecting the causes for complaints with commonly used indoor air measurements is difficult. This study presents data on perceived and measured IAQ in six comprehensive school buildings in Finland. The aim of this study was to discover the possible differences of perceived and measured IAQ between schools with reported IAQ complaints and schools without reported IAQ complaints. The initial categorisation of schools with ('problematic schools') and without ('comparison schools') complaints was ensured via a validated indoor climate survey and a recently developed online questionnaire, which were completed by 186 teachers and 1268 students from the six schools. IAQ measurements of physical parameters, gaseous pollutants, particulate matter and bioaerosols were conducted in four problematic school buildings (26 classrooms) and two comparison school buildings (12 classrooms). Using air sampling as well as exhaust air filters and classroom settled dust to detect the presence of elevated concentrations of airborne cultivable microbes and pathogenic, toxigenic and mycoparasitic Trichoderma strains were the most indicative methods in distinguishing problematic schools from comparison schools. Other IAQ-related measurements did not detect clear differences between problematic and comparison schools, as the concentration levels were very low. The results indicate that the complaints reported by occupants could have been related to excess moisture or mould problems that had not been found or repaired. Ventilation pressure condition investigations and simultaneous exhaust and supply air filter dust culture should be addressed precisely in future studies.

Endotoxin, food allergen sensitization, and food allergy: A complementary epidemiologic and experimental study

BACKGROUND

Household endotoxin levels have been variably associated with risk for asthma and atopy.

METHODS

We studied participants from the 2005-2006 National Health and Nutrition Examination Survey (NHANES, n = 6963), a large cohort representative of the US population (aged 1-84 years). We built logistic regression models to test for associations between house dust endotoxin and sensitization to specific foods (milk, egg, and peanut). To experimentally explore the detected epidemiologic associations, peripheral blood mononuclear cells (PBMCs) were collected from 21 children (aged 1-19 years) mono-food allergic (ie, sensitized and clinically reactive) to milk, egg, or peanut and nonallergic controls for stimulation with endotoxin and secreted cytokine measurement. For each food allergy, linear mixed-effects models were built to test the association between endotoxin stimulation and cytokine level.

RESULTS

Among NHANES subjects, the geometric mean household endotoxin level was 15.5 EU/mg (GSE 0.5). Prevalence of food allergen sensitization (sIgE ≥ 0.35 kU_A /L) varied by food: milk 5.7%, egg 4.0%, and peanut 7.9%. In models adjusted for potential confounders (age, race, country of birth, total people per household, US region, and history of wheezing in the past year), household endotoxin level was associated with sensitization to milk (OR 1.7, 95% CI 1.2-2.1) and egg (OR 1.4, 95% CI 1.01-1.9), but not peanut (OR 0.98, 95% CI 0.8-1.2). Interferon-γ levels of endotoxin-stimulated PBMCs from children allergic to milk or egg, but not peanut, were significantly lower compared to controls in linear mixed-effects models adjusted for repeated measures, experimental variables, age, and inter-individual variability (P-values .007, .018, and .058, respectively).

CONCLUSION

Higher household endotoxin is associated with increased odds of milk and egg sensitization. Altered cytokine responsiveness to endotoxin is also observed in PBMCs from individuals with milk and egg allergy.

New Directions in Pediatric Asthma

Childhood asthma affects many children placing them at significant risk for health care utilization and school absences. Several new developments relevant to the field of pediatric asthma have occurred over the last 5 years; yet, there is much more to learn. It is poorly understood how to prevent the disease, optimally address environmental challenges, or effectively manage poor adherence. Moreover, it is not clear how to customize therapy by asthma phenotype, age group, high risk groups, or severity of disease. Highlights of advances in pediatric asthma are reviewed and multiple essential areas for further exploration and research are discussed.

Endotoxin and Der p1 allergen levels in indoor air and settled dust in day-care centers in Tehran, Iran

BACKGROUND

Allergens like endotoxin and mite allergen Der p 1 are associated with early wheezing and asthma morbidity. Day-care centers can be an important source of exposure to allergens. The aim of this study was to evaluate children's exposure to endotoxin and mite allergen (Der p 1) associated with total suspended particulate matter (TSP) and settled dust in day-care centers in two phases in years of 2015 and 2016 in Tehran city, Iran.

METHODS

Endotoxin and mite allergen Der p 1 in TSP and settled dust were measured in 23 day-care centers in Tehran. After collecting dust samples and weighting them, and then their extraction, Endotoxin and Der p 1 allergen were determined using QCL-1000 Endpoint chromogenic LAL Assay and ELISA, respectively.

RESULTS

The mean concentrations of endotoxin and mite allergen Der p 1 in settled dust were 0.3 EU/mg and 0.2 ng/mg, respectively. The mean concentration of endotoxin and mite allergen Der p 1 in indoor air TSP were 0.8 EU/m³ and 0.4 ng/m³, respectively. A significant negative correlation was found between endotoxin both in settled dust and in TSP with measured relative humidity in winter. Also, moderate correlation was observed between Der p 1 in settled dust and relative humidity in winter; however, the correlation between allergen in TSP and relative humidity was not significant.

CONCLUSION

Day-care centers can be an important source of endotoxin and Der p 1 allergen, so, implementation of proper interventions in these places can reduce exposure to them.

Pediatric Inner-City Asthma

Inner-city children with asthma are known to have high disease mortality and morbidity. Frequently, asthma in this high-risk population is difficult to control and more severe in nature. Several factors, including socioeconomic hardship, ability to access to health care, adherence to medication, exposure to certain allergens, pollution, crowd environment, stress, and infections, play an important role in the pathophysiology of inner-city asthma. Comprehensive control of home allergens and exposure to tobacco smoke, the use of immune based therapies, and school-based asthma programs have shown promising results in asthma control in this population.

Inner-City Asthma in Children

Asthma in inner-city children is often severe and difficult to control. Residence in poor and urban areas confers increased asthma morbidity even after adjusting for ethnicity, age, and gender. Higher exposure to household pests, such as cockroaches and mice, pollutants and tobacco smoke exposure, poverty, material hardship, poor-quality housing, differences in health care quality, medication compliance, and heath care access also contribute to increased asthma morbidity in this population. Since 1991, the National Institutes of Allergy and Infectious Diseases established research networks: the National Cooperative Inner-City Asthma Study (NCICAS), the Inner-City Asthma Study (ICAS), and the Inner-City Asthma Consortium (ICAC), to improve care for this at risk population. The most striking finding of the NCICAS is the link between asthma morbidity and the high incidence of allergen sensitization and exposure, particularly cockroach. The follow-up ICAS confirmed that reductions in household cockroach and dust mite were associated with reduction in the inner-city asthma morbidity. The ICAC studies have identified that omalizumab lowered fall inner-city asthma exacerbation rate; however, the relationship between inner-city asthma vs immune system dysfunction, respiratory tract infections, prenatal environment, and inner-city environment is still being investigated. Although challenging, certain interventions for inner-city asthma children have shown promising results. These interventions include family-based interventions such as partnering families with asthma-trained social workers, providing guidelines driven asthma care as well as assured access to controller medication, home-based interventions aim at elimination of indoor allergens and tobacco smoke exposure, school-based asthma programs, and computer/web-based asthma programs.

The Effects of the Environment on Asthma Disease Activity

Asthma is highly prevalent and causes significant morbidity in children. The development of asthma depends on complex relationships between genetic predisposition and environmental modifiers of immune function. The biological and physical environmental factors include aeroallergens, microbiome, endotoxin, genetics, and pollutants. The psychosocial environment encompasses stress, neighborhood safety, housing, and discrimination. They all have been speculated to influence asthma control and the risk of developing asthma. Control of the factors that contribute to or aggravate symptoms, interventions to eliminate allergen exposure, guidelines-based pharmacologic therapy, and education of children and their caregivers are of paramount importance.

School exposure and asthma

OBJECTIVE

To provide a comprehensive overview of common school exposures and the association between school exposures and pediatric asthma morbidity.

DATA SOURCES

A comprehensive literature review was performed using PubMed.

STUDY SELECTIONS

Full-length, peer-reviewed studies published in English were considered for review. In vivo, in vitro, and animal studies were excluded. Studies of school exposure to cockroach, mouse, dust mite, dog, cat, molds, pollution, and endotoxin associated with asthma and asthma morbidity were considered.

RESULTS

The current literature establishes an association between school exposure and pediatric asthma morbidity. There is a need for ongoing research to evaluate the effects of school-based environmental interventions on asthma morbidity.

CONCLUSION

It is evident that the indoor school environment is a significant reservoir of allergens, molds, pollutants, and endotoxin and that there is an association between school exposure and pediatric asthma morbidity. School-based interventions have the potential for substantial individual, community, and public health benefit. It is important that researchers continue to study the health effects associated with school exposures and assess cost-effectiveness of multifaceted school-based interventions.

Indoor air quality in schools of a highly polluted south Mediterranean area

This study aimed at surveying lower secondary schools in southern Italy, in a highly polluted area. A community close to an industrial area and three villages in rural areas was investigated. Indoor temperature, relative humidity (RH), gaseous pollutants (CO₂ and NO₂ ), selected biological pollutants in indoor dust, and the indoor/outdoor mass concentration and elemental composition of PM_2.5 were ascertained. Temperature and RH were within, or close to, the comfort range, while CO₂ frequently exceeded the threshold of 1000 ppm, indicating inadequate air exchange rate. In all the classrooms, median NO₂ levels were above the WHO threshold value. Dermatophagoides p. allergen concentration was below the sensitizing threshold, while high endotoxin levels were detected in the classrooms, suggesting schools may produce significant risks of endotoxin exposure. Concentration and solubility of PM_2.5 elements were used to identify the sources of indoor particles. Indoor concentration of most elements was higher than outdoors. Resuspension was responsible for the indoor increase in soil components. For elements from industrial emission (Cd, Co, Ni, Pb, Sb, Tl, V), the indoor concentration depended on penetration from the outside. For these elements, differences in rural vs industrial concentrations were found, suggesting industrial sources may influence indoor air quality nearby schools.

School Environmental Intervention Programs

Exposure to indoor allergens and pollutants plays a significant part in the development of asthma and its associated morbidity. Inner-city children with asthma are disproportionately affected by these exposures with increased asthma morbidity. Although years of previous research have linked exposures in the urban home environment with significant childhood asthma disease, many of these allergens are also present in inner-city school environments. Therefore, evaluation of the school environment of patients with asthma is also essential. School-based environmental interventions may offer benefit for this problem and has the potential to help many children with asthma at once in a cost-effective manner. It is important that environmental health researchers continue to assess which interventions are most practical and result in the greatest measurable improvements.

Recent advances in environmental controls outside the home setting

PURPOSE OF REVIEW

It has been well studied that aeroallergen, mold, and airborne pollutant exposure in the inner-city home environment is associated with significant childhood asthma morbidity. Although the home environment has been extensively studied, the school environment is less well understood.

RECENT FINDINGS

In this article, we discuss the relationship between environmental exposures within the school and daycare environment and pediatric asthma morbidity and novel environmental interventions designed to help mitigate pediatric asthma morbidity.

SUMMARY

Studies assessing environmental exposures outside the home environment and interventions to mitigate these exposures have the potential to reduce pediatric asthma morbidity. Further study in this area should focus on the complex cost benefit analyses of environmental interventions outside the home setting, while controlling for the home environment.

Characterization of the bacterial and fungal microbiome in indoor dust and outdoor air samples: a pilot study

Environmental microbes have been associated with both protective and adverse health effects in children and adults. Epidemiological studies often rely on broad biomarkers of microbial exposure (i.e. endotoxin, 1 → 3-beta-d-glucan), but fail to identify the taxonomic composition of the microbial community. Our aim was to characterize the bacterial and fungal microbiome in different types of environmental samples collected in studies of human health effects. We determined the composition of microbial communities present in home, school and outdoor air samples by amplifying and sequencing regions of rRNA genes from bacteria (16S) and fungi (18S and ITS). Samples for this pilot study included indoor settled dust (from both a Boston area birth cohort study on Home Allergens and Asthma (HAA) (n = 12) and a study of school exposures and asthma symptoms (SICAS) (n = 1)), as well as fine and coarse concentrated outdoor ambient particulate (CAP) samples (n = 9). Sequencing of amplified 16S, 18S, and ITS regions was performed on the Roche-454 Life Sciences Titanium pyrosequencing platform. Indoor dust samples were dominated by Gram-positive bacteria (Firmicutes and Actinobacteria); the most abundant bacterial genera were those related to human flora (Streptococcus, Staphylococcus, Corynebacterium and Lactobacillus). Outdoor CAPs were dominated by Gram-negative Proteobacteria from water and soil sources, in particular the genera Acidovorax, and Brevundimonas (which were present at very low levels or entirely absent in indoor dust). Phylum-level fungal distributions identified by 18S or ITS regions showed very similar findings: a predominance of Ascomycota in indoor dust and Basidiomycota in outdoor CAPs. ITS sequencing of fungal genera in indoor dust showed significant proportions of Aureobasidium and Leptosphaerulina along with some contribution from Cryptococcus, Epicoccum, Aspergillus and the human commensal Malassezia. ITS sequencing detected more than 70 fungal genera in indoor dust not observed by culture. Microbiome sequencing is feasible for different types of archived environmental samples (indoor dust, and low biomass air particulate samples), and offers the potential to study how whole communities of microbes (including unculturable taxa) influence human health.

Inflammatory potential in relation to the microbial content of settled dust samples collected from moisture-damaged and reference schools: results of HITEA study

Aiming to identify factors causing the adverse health effects associated with moisture-damaged indoor environments, we analyzed immunotoxicological potential of settled dust from moisture-damaged and reference schools in relation to their microbiological composition. Mouse RAW264.7 macrophages were exposed to settled dust samples (n = 25) collected from moisture-damaged and reference schools in Spain, the Netherlands, and Finland. After exposure, we analyzed production of inflammatory markers [nitric oxide (NO), tumor necrosis factor-α (TNF-)α, interleukin (IL)-6, and macrophage inflammatory protein (MIP)2] as well as mitochondrial activity, viability, apoptosis, and cell cycle arrest. Furthermore, particle counts, concentration of selected microbial groups as well as chemical markers such as ergosterol, 3-hydroxy fatty acids, muramic acid, endotoxins, and glucans were measured as markers of exposure. Dust from moisture-damaged schools in Spain and the Netherlands induced stronger immunotoxicological responses compared to samples from reference schools; the responses to Finnish samples were generally lower with no difference between the schools. In multivariate analysis, IL-6 and apoptosis responses were most strongly associated with moisture status of the school. The measured responses correlated with several microbial markers and numbers of particles, but the most important predictor of the immunotoxicological potential of settled dust was muramic acid concentration, a marker of Gram-positive bacteria.

Inner-city asthma: special considerations for management

PURPOSE OF REVIEW

Asthma is prevalent in inner-city populations, exhibiting significant morbidity and mortality. This review focuses on the consequential findings of recent literature, providing insight into onset of asthma, complicating factors, prediction of exacerbations, and novel treatment strategies.

RECENT FINDINGS

Analyses of environmental influence on inner-city children demonstrated novel interactions, implicating potentially protective benefits from early life exposures to pests and pets and isolating detrimental effects of air pollution on asthma morbidity. Through detailed characterization of inner-city asthmatics, predictors of seasonal exacerbations surfaced. Focused, season-specific treatment of inner-city asthmatics with omalizumab identified those most likely to benefit from season-tailored therapy. Comparative studies of urban and rural populations revealed that race and household income, rather than location of residence, impose the greatest risk for increased asthma prevalence and morbidity.

SUMMARY

Challenging previously conceived exposure-disease relationships, recent literature has elucidated new avenues in the complex interplay between immunologically active exposures and their effects on inner-city asthma. These findings, and improved understanding of other relevant exposures, could steer the direction of primary (and secondary) disease prevention research. Moreover, careful identification of asthma characteristics has effectively established predictors of exacerbations, highlighting individuals for which additional therapies are warranted and for whom such treatments are most likely to be effective.

School Endotoxin Exposure and Asthma Morbidity in Inner-city Children

BACKGROUND

Endotoxin exposure is associated with airway inflammation. Children spend 6 to 8 h/d in school, yet the effect of school-specific endotoxin exposure on asthma morbidity is not well understood.

METHODS

In this longitudinal cohort study, 248 students with asthma, from 38 inner-city schools, underwent baseline phenotyping and follow-up. Clinical outcomes were evaluated throughout the academic school year and linked to classroom-specific dust and air endotoxin levels as well as home dust endotoxin levels. The primary outcome was maximum asthma symptom-days per 2-week period.

RESULTS

Classrooms had higher settled dust endotoxin levels compared with homes (14.3 endotoxin unit/mg vs 11.3 endotoxin unit/mg; P = .02). Airborne endotoxin levels exceeding recommended occupational exposure limits for adults were recorded in 22.0% of classrooms. Classroom air endotoxin levels were independently associated with increased maximum symptom-days in children with nonatopic asthma, but not in those with atopic asthma (interaction P = .03). Adjusting for home exposures, classroom endotoxin exposure was independently associated with a dose-dependent increase in asthma symptom-days for children with nonatopic asthma (adjusted incidence rate ratio, 1.16 [95% CI, 1.03-1.31]; P = .02). In these subjects, maximum symptom-days increased by 1.3 days for each 14-day period when comparing students in classrooms with the lowest endotoxin levels compared with average measured levels.

CONCLUSIONS

Inner-city children with asthma are exposed to high levels of airborne endotoxin at school, resulting in increased asthma symptoms in children with nonatopic asthma. Mitigation of school-related exposures may represent a strategy to decrease asthma morbidity in this population.

TRIAL REGISTRY

ClinicalTrials.gov; No.: NCT01756391; URL: www.clinicaltrials.gov.

The school environment and asthma in childhood

In this article, we discuss the relationship between environmental exposures within the school environment and pediatric asthma morbidity. This article will conclude by reviewing novel school based asthma education and therapeutic programs and environmental interventions designed to help mitigate pediatric asthma morbidity.

Sleeping on animal fur is related to asthma outcomes in later childhood

Animal furs might represent a "proxy" for high and diverse microbial exposures within a critical time window of immune development. We assessed whether sleeping on animal fur shortly after birth is associated with asthma and atopy up to the age of 10 years. LISAplus participants (n=2441) from Munich and Leipzig, Germany, were included in the analysis. Animal fur exposure, cofactors and health outcomes were obtained periodically up to 10 years of age by parental questionnaires. Information on specific IgE to aeroallergens was available at 10 years. Cytokine-producing peripheral T-cells were assessed in a subgroup of children at 2 and 3 years. Confounder-adjusted associations were evaluated using logistic regression analyses. Sleeping on animal fur was very common (55%). In adjusted logistic regression analyses, sleeping on animal fur was inversely associated with recurrent early wheezing at 4 years (adjusted OR 0.75, 95% CI 0.61-0.93) and current asthma at 6 years (adjusted OR 0.56, 95% CI 0.31-1.01). Furthermore, sleeping on animal fur during the first 3 months of life was significantly associated with a persistently stimulated interferon-γ response until the age of 3 years. Animal fur could be an effective measure of creating environments associated with higher microbial exposure.

Obstructive airway disease in urban populations

PURPOSE OF REVIEW

Obstructive lung disease (OLD), including asthma and chronic obstructive pulmonary disease, has a more substantial prevalence and morbidity in urban populations. This review highlights recent publications examining the epidemiology, risk factors and interventions concerning OLD in urban populations.

RECENT FINDINGS

Using a variety of approaches, estimates of asthma prevalence in urban populations range from 5 to 25%. Early life exposures including in-utero cigarette smoke, postnatal bisphenol A, home and school particulates, and environmental air pollution contribute to increased OLD prevalence and symptom manifestations. Individuals with increased exposure to traffic-related pollution demonstrate abnormal inflammatory and lung function profiles. Obesity, more common in urban populations, is likely both a risk factor for asthma as well as contributor to poor control. Interventions targeted at home-based education and assessments are efficacious and cost-effective in improving outcomes of OLD in urban settings.

SUMMARY

The burden of OLD in urban populations is driven by maternal, environmental and acquired factors. There are few recent data regarding risk factors and interventions for urban cohorts with chronic obstructive pulmonary disease. The complex interplay of race, socioeconomic status, environmental exposures and healthcare access in the urban population requires continued research efforts.

Introducing an environmental assessment and intervention program in inner-city schools

Home-based environmental interventions have demonstrated clinical benefit for children with asthma. Although much is known about school-based exposures, few studies have comprehensively examined the role the school environment plays in asthma and how effectively changing the environment might reduce morbidity when adjusting for exposures in the home. This review summarizes the importance and common challenges of school-based environmental assessment and intervention studies linked to health effects. We focus on the key components of study development and the challenges and benefits to implementation.

Early exposure to bio-contaminants and asthma up to 10 years of age: results of the HITEA study

Inverse associations have been found between exposure to bio-contaminants and asthma and allergies. The aim of this study was to prospectively assess whether early exposure to bio-contaminants in dust is associated with asthma and allergy later in childhood among children from (sub)-urban areas. In subsets of three European birth cohorts (PIAMA: n=553; INMA: n=481; and LISAplus: n=395), endotoxin, (1,3,)-β-d-glucan and extracellular polysaccharide were measured in dust from living rooms shortly after birth. Current asthma at 6 years and 10 years of age and ever asthma up to 10 years of age were assessed by parental questionnaires. Specific IgE levels at 8 years (PIAMA) and 10 years (LISAplus) were available. Adjusted, cohort-specific logistic regression analyses were performed. Higher endotoxin concentrations were positively associated with current asthma at 6 years of age in PIAMA (adjusted OR 1.96, 95% CI 1.07-3.58), but were inversely related with ever asthma up to 10 years of age in INMA (adjusted OR 0.39, 95% CI 0.16-0.94). No associations with asthma were found for LISAplus. No associations were observed with atopic sensitisation in all cohorts. All associations with (1,3)-β-d-glucan and extracellular polysaccharide were statistically nonsignificant. The suggested immunological mechanisms of early exposure to bio-contaminants with regards to asthma and allergy might be different for children growing up in (sub)-urban environments.

Social disadvantage and asthma control in children

This review discusses various aspects of social disadvantage and their association with poor asthma control, including socioeconomic status, exposure to psychosocial stress and violence, minority affiliation, environmental concerns such as allergens and pollution, and poverty in rural settings. Each of these elements has been linked with worsened asthma outcomes in children. Known and hypothesized mechanisms behind these associations are described in an effort to further understand the complex entity of poorly controlled asthma among socially deprived children. Intervention studies to improve asthma outcomes in these vulnerable populations are also described.

Dampness, bacterial and fungal components in dust in primary schools and respiratory health in schoolchildren across Europe

BACKGROUND

Respiratory health effects of damp housing are well recognised, but less is known about the effect of dampness and water damage in schools. The HITEA study previously reported a higher prevalence of respiratory symptoms in pupils from moisture damaged schools, but the role of specific microbial exposures remained unclear.

OBJECTIVES

To study associations between school dampness, levels of fungal and bacterial markers, respiratory symptoms and lung function in children.

METHODS

Primary schools in Spain, the Netherlands and Finland were selected on the basis of the observed presence (n=15) or absence (n=10) of moisture, dampness and/or mould. Settled dust was repeatedly sampled in 232 classrooms and levels of 14 different microbial markers and groups of microbes were determined. Parental reports of respiratory symptoms were available from 3843 children aged 6-12 years, of whom 2736 provided acceptable forced spirometry testing. Country-specific associations between exposure and respiratory health were evaluated by multilevel mixed-effects logistic and linear regression models and combined using random-effects meta-analysis.

RESULTS

The prevalence of respiratory symptoms was higher in moisture damaged schools, being more pronounced in Finnish pupils. Effects on lung function were not apparent. Levels of microbial markers were generally higher in moisture damaged schools, varied by season and were lower in Finnish schools. Wheeze tended to be inversely associated with microbial levels. All other respiratory symptoms were not consistently associated with microbial marker levels.

CONCLUSIONS

Health effects of moisture and microbial exposures may vary between countries, but this requires further study.

The indoor environment and inner-city childhood asthma

OBJECTIVE

Exposure to indoor pollutants and allergens has been speculated to cause asthma symptoms and exacerbations and influence the risk of developing asthma. The aim of this article is to review the medical literature regarding the role of the indoor environment on inner-city childhood asthma.

DATA SOURCES

A literature search was performed in PubMed. Studies focusing on inner-city indoor allergen, childhood asthma, and environmental controls were included.

RESULTS

The prevalence of asthma in children is increasing especially in inner-city area. Exposure to high levels of indoor allergens and pollutants has been related to asthma development. Studies have shown that mouse, cockroach, pets, dust mite, mold, tobacco smoke, endotoxin and nitrogen dioxide are the important exposures. Recent studies have shown that indoor environmental control is beneficial in reducing asthma morbidity and development.

CONCLUSIONS

Inner-city children are exposed to various indoor allergens and pollutants that may lead to asthma development and exacerbation of existing asthma. Multifaceted environmental controls are beneficial in improving asthma symptom and maybe a viable prevention strategy. Further prospective studies of environmental intervention are needed to further identify effective strategies to improve and prevent asthma symptoms in inner-city children.

Endotoxin levels in settled airborne dust in European schools: the HITEA school study

Indoor exposure to microbial agents is known to influence respiratory health. Besides home exposure, exposure in schools can affect respiratory health. In this study, we measured endotoxin in settled dust in primary schools in three European countries from three different geographical regions with different climates. Our aim was to characterize endotoxin levels in primary schools and evaluate associations with potential determinants. Endotoxin levels were repeatedly assessed in 23 schools in Spain (n = 7), the Netherlands (n = 10), and Finland (n = 6) using electrostatic dustfall collectors. In total, 645 measurements were taken in 237 classrooms. Endotoxin levels differed significantly between countries; Dutch schools had the highest levels, while Finnish schools showed the lowest levels. In each country, differences in endotoxin levels were observed between schools and over the sampling periods. Estimates improved after adjustment for sampling period. Factors affecting endotoxin levels in a school differed per country. In general, endotoxin levels were higher in lower grades and in classrooms with higher occupancy. School endotoxin levels may contribute significantly to total endotoxin exposure in children and teachers. As the correlation between the repeated measurements is reasonable, single endotoxin measurements form a reasonable basis for estimating annual endotoxin levels in schools.

Environmental remediation in the treatment of allergy and asthma: latest updates

In the modern era, the prevalence of asthma and allergies are increasing. It has been speculated that environmental exposures are contributing to this rise. Several studies demonstrate that common indoor allergen exposures exacerbate asthma. Minimizing exposure to allergens and remediating the environment play a critical role in the treatment of asthma and allergies. The most effective environmental control measures are tailored multifaceted interventions which include education, thorough cleaning, using high-efficiency particulate air (HEPA) filters, integrated pest management, and maintenance of these practices.

Allergens and β-glucans in dutch homes and schools: characterizing airborne levels

Background

Indoor air quality has an effect on respiratory health. Children are more vulnerable to a decreased indoor air quality as their lungs are still developing. We measured levels of allergens and β-(1,3)-glucans in 19 school buildings and determined whether measured levels could be reproduced. School levels were compared to those in 169 homes and the effect of building characteristics on both home and school exposure was explored.

Methods

Electrostatic Dust fall Collectors were placed in school buildings for 8 weeks and in homes for 2 weeks to collect settled airborne dust. Cat, dog, and mouse allergen levels, domestic mite antigen levels and β-(1,3)-glucans were measured in the extracts from the collectors. Results were corrected for sampling duration. Using questionnaire data, relations between measured levels and building and classroom characteristics were explored.

Results

In schools, exposure levels were highest in classrooms and were influenced by the socioeconomic status of the children, the season measurements were performed, moisture status of the building and pet ownership. Repeated measurements in different seasons and over the years showed significantly different levels. Home exposure was influenced by socioeconomic status, occupancy and pet ownership. Domestic mite antigen was found in higher levels in extracts from homes compared to schools while pet allergen levels were 13 times higher in schools compared to homes without pets. For mouse allergen overall levels of exposure were low but still two times higher in schools compared to homes. Levels of β-(1,3)-glucans were also approximately two times higher in schools than in homes.

Conclusion

Exposure levels of several allergens and β-(1,3)-glucans in schools differ over time and are higher than in homes. For children, exposure levels measured at school could contribute to their total exposure as especially animal allergen levels can be much higher in schools compared to homes.

High prevalence of allergy in North Cypriot children

BACKGROUND

The ISAAC (the International Study of Asthma and Allergies in Childhood) questionnaire has been used to standardize research on the prevalence of asthma in children since 1991.

AIM

In this Phase I study, the prevalence of asthma, other allergic diseases and atopy was evaluated in North Cyprus.

METHODS

The ISAAC questionnaire was distributed to grades I-V schoolchildren. Data were obtained from parents of 580 schoolchildren aged between 7 and 12 years attending a primary school in Nicosia, the capital of North Cyprus. Of those, a sub-group of 97 (16.7%) randomly selected children were evaluated by skin prick test (SPT) and lung function test (LFT).

RESULTS

The prevalence rates of asthma ever, current wheezing and SPT-positivity were 20.8%, 10% and 68%, respectively. The prevalence of atopy was significantly higher in the randomly selected subgroup of 97 (68%) patients subjected to SPT and LFT, and the house dust mite (HDM) was the allergen to which children were most frequently sensitized.

CONCLUSIONS

In northern Cyprus, the prevalence rates of asthma, allergic diseases and atopic sensitization in 7-12-year-old children are extremely high. Sensitization to HDM is a risk factor for the development of asthma.

Beta-2-Adrenergic Receptor Methylation Influences Asthma Phenotype in The School Inner City Asthma Study

Asthma is the most common chronic illness of childhood and inner city residents suffer a disproportionately high rate of asthma diagnosis and asthma morbidity. The School Inner City Asthma Study investigates the school classroom based environmental exposures that may lead to asthma morbidity in inner city school children with asthma. Within this cohort, we investigated the role of methylation at the promoter region of the beta-2-adrenergic receptor in relation to asthma morbidity. We found that high levels of methylation in the region studied was significantly associated with decreased report of dyspnea and trended towards significance for lower levels of asthma symptoms and airway obstruction. This Research Highlight discusses the findings of the recent study and the investigators' active research endeavors.

Endotoxins in indoor air and settled dust in primary schools in a subtropical climate

Endotoxins can significantly affect the air quality in school environments. However, there is currently no reliable method for the measurement of endotoxins, and there is a lack of reference values for endotoxin concentrations to aid in the interpretation of measurement results in school settings. We benchmarked the "baseline" range of endotoxin concentration in indoor air, together with endotoxin load in floor dust, and evaluated the correlation between endotoxin levels in indoor air and settled dust, as well as the effects of temperature and humidity on these levels in subtropical school settings. Bayesian hierarchical modeling indicated that the concentration in indoor air and the load in floor dust were generally (<95th percentile) <13 EU/m(3) and <24,570 EU/m(2), respectively. Exceeding these levels would indicate abnormal sources of endotoxins in the school environment and the need for further investigation. Metaregression indicated no relationship between endotoxin concentration and load, which points to the necessity for measuring endotoxin levels in both the air and settled dust. Temperature increases were associated with lower concentrations in indoor air and higher loads in floor dust. Higher levels of humidity may be associated with lower airborne endotoxin concentrations.

Diet-induced obesity reprograms the inflammatory response of the murine lung to inhaled endotoxin

The co-occurrence of environmental factors is common in complex human diseases and, as such, understanding the molecular responses involved is essential to determine risk and susceptibility to disease. We have investigated the key biological pathways that define susceptibility for pulmonary infection during obesity in diet-induced obese (DIO) and regular weight (RW) C57BL/6 mice exposed to inhaled lipopolysaccharide (LPS). LPS induced a strong inflammatory response in all mice as indicated by elevated cell counts of macrophages and neutrophils and levels of proinflammatory cytokines (MDC, MIP-1γ, IL-12, RANTES) in the bronchoalveolar lavage fluid. Additionally, DIO mice exhibited 50% greater macrophage cell counts, but decreased levels of the cytokines, IL-6, TARC, TNF-α, and VEGF relative to RW mice. Microarray analysis of lung tissue showed over half of the LPS-induced expression in DIO mice consisted of genes unique for obese mice, suggesting that obesity reprograms how the lung responds to subsequent insult. In particular, we found that obese animals exposed to LPS have gene signatures showing increased inflammatory and oxidative stress response and decreased antioxidant capacity compared with RW. Because signaling pathways for these responses can be common to various sources of environmentally induced lung damage, we further identified biomarkers that are indicative of specific toxicant exposure by comparing gene signatures after LPS exposure to those from a parallel study with cigarette smoke. These data show obesity may increase sensitivity to further insult and that co-occurrence of environmental stressors result in complex biosignatures that are not predicted from analysis of individual exposures.

Indoor air quality and sources in schools and related health effects

Good indoor air quality in schools is important to provide a safe, healthy, productive, and comfortable environment for students, teachers, and other school staff. However, existing studies demonstrated that various air pollutants are found in classrooms, sometimes at elevated concentrations. Data also indicated that poor air quality may impact children's health, in particular respiratory health, attendance, and academic performance. Nevertheless, it should be noted that there are other adverse health effects that are less documented. Few data exist for teachers and other adults that work in schools. Allergic individuals seem to be at a higher risk for adverse respiratory health consequences. Air quality improvement represents an important measure for prevention of adverse health consequences in children and adults in schools.

The effects of various doses of bacterial lipopolysaccharide on the expression of CD63 and the release of histamine by basophils of atopic and non-atopic patients

OBJECTIVE

We tested the effect of various doses of bacterial lipopolysaccharide (LPS, endotoxin) on the expression of CD63 and the in vitro release of histamine by basophils stimulated with ragweed allergen in patients with or without ragweed and mite allergies.

METHODS

The peripheral blood of 11 patients with ragweed allergy, 10 patients with mite allergy and 14 control patients was incubated with ragweed allergen extract following pretreatment with varying doses of LPS. The expression of CD63 in basophils was measured by flow cytometry, and the release of histamine was determined by ELISA.

RESULTS

In the samples of patients with ragweed allergy that were exposed to specific allergen, only high doses of LPS significantly elevated the expression of CD63 (200 ng/ml; 1,000 EU/ml) and the release of histamine (2,000 ng/ml; 10,000 EU/ml). There was no effect of LPS in any other cases.

CONCLUSIONS

Bacterial LPS (endotoxin) concentrations higher than 200 ng/ml (1,000 EU/ml), which rarely occurs in nature, could only activate the basophils from atopic patients whilst in the presence of the specific allergen. Thus, the restoration of the urban, "microbe-poor" milieu with endotoxin (as LPS) can be a promising and harmless approach for allergy prevention.