The role of allergy in the development of airway inflammation in children

Environmental exposure to agrochemicals and allergic diseases in preschool children in high grown tea plantations of Sri Lanka

Background

Exposure to agrochemicals is one of the many aetiological agents, postulated to cause allergic diseases. In this study, we have compared the prevalence of allergic diseases among preschool children growing in environments exposed to agrochemicals and artificial fertilizers with those who are not exposed to them.

Methods

Our study was conducted on preschool children in two tea estates in the hill country of Sri Lanka, one using conventional agricultural practices and the other using organic practices. Data collection was done by using an interviewer administered questionnaire. Children with potential allergic conditions were further evaluated clinically by medical officers. Blood was drawn for full blood count and a blood picture.

Results

Data from 81 preschool children from an organic estate (Haputale) and 101 preschool children from a conventional estate (Thalawakelle) were analysed. Wheezing was noted in 41.2% of children from the organic estate and 59.8% from the conventional estate. The respective percentages for allergic rhinitis were as 37.7% and 82.5% while for eczema they were 17.5% and 20.28%. Among the two populations percentages of eosinophilia > 600/mm³ were as 26.1% and 34.1% respectively.

Conclusions

Allergic conditions were more common in preschool children with environmental exposure to agrochemicals and chemical fertilizers when compared to that of organic cultivation systems. Stricter rules are needed when using agrochemicals to prevent their harmful effects, including allergic diseases, on children.

Hypoxia-inducible factor-1α inhibition modulates airway hyperresponsiveness and nitric oxide levels in a BALB/c mouse model of asthma

Hypoxia-inducible factor (HIF)-1α is a master regulator of inflammation and is upregulated in alveolar macrophages and lung parenchyma in asthma. HIF-1α regulates select pathways in allergic inflammation, and thus may drive particular asthma phenotypes. This work examines the role of pharmacologic HIF-1α inhibition in allergic inflammatory airway disease (AIAD) pathogenesis in BALB/c mice, which develop an airway hyperresponsiveness (AHR) asthma phenotype. Systemic treatment with HIF-1α antagonist YC-1 suppressed the increase in HIF-1α expression seen in control AIAD mice. Treatment with YC-1 also decreased AHR, blood eosinophilia, and allergic inflammatory gene expression: IL-5, IL-13, myeloperoxidase and iNOS. AIAD mice had elevated BAL levels of NO, and treatment with YC-1 eliminated this response. However, YC-1 did not decrease BAL, lung or bone marrow eosinophilia. We conclude that HIF-1α inhibition in different genetic backgrounds, and thus different AIAD phenotypes, decreases airway resistance and markers of inflammation in a background specific manner.

CAPSULE SUMMARY

Asthma is a common disease that can be difficult to control with current therapeutics. We describe how pharmacologic targeting of a specific transcription factor, HIF-1α, suppresses asthmatic airway reactivity and inflammation.

Factors associated with the time to the first wheezing episode in infants: a cross-sectional study from the International Study of Wheezing in Infants (EISL)

Male gender, asthmatic heredity, perinatal tobacco smoke exposure and respiratory infections have been associated with wheeze in the first years of life, among other risk factors. However, information about what factors modify the time to the first episode of wheeze in infants is lacking. The present study analyses which factors are associated with shorter time to the first episode of wheeze in infants. Parents of 11- to 24-month-old children were surveyed when attending their health-care centres for a control visit. They answered a questionnaire including the age in months when a first wheeze episode (if any) had occurred (outcome variable). The study was performed in 14 centres in Latin America (LA) and in 8 centres in Europe (EU) (at least 1,000 infants per centre). Factors known to be associated with wheezing in the cohort were included in a survival analysis (Cox proportional hazards model). Summary hazard ratios adjusted for all risk factors (aHR) were calculated using the meta-analysis approach with random effects. A total of 15,067 infants had experienced wheezing at least once, out of 35,049 surveyed. Male gender in LA (aHR 1.05, 95% confidence interval (CI) 1.00-1.10, P=0.047), parental asthma in LA and EU (aHR 1.05, 95% CI 1.00-1.11, P=0.037), infant eczema in EU (aHR 1.25, 95% CI 1.12-1.39, P<0.001) and having a cold during the first 3 months in LA and EU (aHR 1.97, 95% CI 1.90-2.04, P<0.001), in LA (aHR 1.98, 95% CI 1.90-2.06, P<0.001) and in EU (aHR 1.91, 95% CI 1.75-2.09, P<0.001) were associated with a shorter period of time to the first episode. Breast feeding for at least 3 months was associated with a longer period, only in LA (aHR 0.91, 95% CI 0.86-0.96, P<0.001). Cold symptoms during the first 3 months is the most consistent factor shortening the time to the first episode of wheezing; breast feeding for ⩾3 months delays it only in LA, whereas eczema shortens it only in EU. Avoiding a common cold in the first months of life could be a good strategy to delay the first wheeze episode; however, cohort studies will help to elucidate this association.

Association of serum levels of polychlorinated biphenyls with IL-8 mRNA expression in blood samples from asthmatic and non-asthmatic Japanese children

BACKGROUND

One of the suggested health outcomes of PCB exposure is childhood asthma.

OBJECTIVES

This study was conducted to find health relevant biomarkers providing the molecular epidemiological evidence for the positive relationship between exposure to PCBs and childhood asthma.

METHODS

Blood samples from fifteen asthmatic children as well as an equal number of non-asthmatic children (average 2 year old) were collected, and were analyzed for PCBs and their select marker expression by using qRT-PCR.

RESULTS

Among biomarkers examined IL-8 expression was significantly correlated to serum levels of PCB #163+164 (P=0.022), #170 (P=0.046), #177 (P=0.022), #178 (P=0.022) and #180+193 (P=0.046) in a dose-dependent manner, which was found only among asthmatic children. In contrast, COX-2 correlations to individual congener levels were recognized only among control subjects, not among asthmatic subjects.

CONCLUSION

Serum concentrations of PCB#163+164, #170, #177, #178 and #180+193 correlate significantly with IL-8 mRNA expressions among asthmatic children.

Effects of Active and Passive Smoking on Ear Infections

Otitis media (OM) is one of the most frequent diseases in young children, causing to visit a physician, and also the most common indication for antibiotic prescription. The peak incidence and prevalence of OM is 6 to 18 months of age. In children, second-hand smoke (SHS) exposure is associated with upper and lower respiratory tract infections, such as acute otitis media (AOM), pneumonia, and bronchitis. Despite the overwhelming evidence of the role of SHS exposure on infant health, a very high proportion of children still continue to be exposed. This important relationship between all kinds of smoking and poor health may not be appreciated universally. With this article, we aim to review tobacco smoke exposure and OM connection. How this exposure may cause OM especially in young children? What can be done to prevent and to reduce the harmfull effects of tobacco smoking?

Prenatal exposure to polycyclic aromatic hydrocarbons, environmental tobacco smoke and asthma

BACKGROUND

Previously, we reported that prenatal exposures to polycyclic aromatic hydrocarbons (PAH) and postnatal environmental tobacco smoke (ETS) in combination were associated with respiratory symptoms at ages 1 and 2 years. Here, we hypothesized that children exposed to both prenatal PAH and ETS may be at greater risk of asthma and seroatopy at ages 5-6 years, after controlling for current pollution exposure.

METHODS

Prenatal PAH exposure was measured by personal air monitoring over 48 h. ETS exposure, respiratory symptoms and asthma at ages 5-6 years were assessed through questionnaire. Immunoglobulin (Ig) E was measured by Immunocap.

RESULTS

A significant interaction between prenatal PAH and prenatal (but not postnatal) ETS exposure on asthma (p < 0.05), but not IgE, was detected. Among children exposed to prenatal ETS, a positive nonsignificant association was found between prenatal PAH exposure and asthma (OR 1.96, 95% CI [0.95-4.05]). Among children without exposure to prenatal ETS, a negative nonsignificant association was found between prenatal PAH exposure and asthma (OR 0.65, 95% CI [0.41-1.01]). Prenatal PAH exposure was not associated with asthma or IgE at age 5-6 years.

CONCLUSIONS

Combined prenatal exposure to PAH and ETS appears to be associated with asthma but not seroatopy at age 5-6. Exposure to PAH alone does not appear associated with either asthma or seroatopy at age 5-6 years. Discerning the differential effects between ETS exposed and ETS nonexposed children requires further study.

Exposure to traffic-related particles and endotoxin during infancy is associated with wheezing at age 3 years

RATIONALE

Murine models demonstrate a synergistic production of reactive oxygen species on coexposure to diesel exhaust particles and endotoxin.

OBJECTIVES

It was hypothesized that coexposure to traffic-related particles and endotoxin would have an additive effect on persistent wheezing during early childhood.

METHODS

Persistent wheezing at age 36 months was assessed in the Cincinnati Childhood Allergy and Air Pollution Study, a high-risk birth cohort. A time-weighted average exposure to traffic-related particles was determined by applying a land-use regression model to the homes, day cares, and other locations where children spent time from birth through age 36 months. Indoor levels of endotoxin were measured from dust samples collected before age 12 months. The relationship between dichotomized (<or>or=75th percentile) traffic-related particle and endotoxin exposure and persistent wheezing, controlling for potential covariates, was examined.

MEASUREMENTS AND MAIN RESULTS

Persistent wheezing at age 36 months was significantly associated with exposure to increased levels of traffic-related particles before age 12 months (OR = 1.75; 95% confidence interval, 1.07-2.87). Coexposure to endotoxin had a synergistic effect with traffic exposure on persistent wheeze (OR = 5.85; 95% confidence interval, 1.89-18.13) after adjustment for significant covariates.

CONCLUSIONS

The association between traffic-related particle exposure and persistent wheezing at age 36 months is modified by exposure to endotoxin. This finding supports prior toxicological studies demonstrating a synergistic production of reactive oxygen species after coexposure to diesel exhaust particles and endotoxin. The effect of early versus later exposure to traffic-related particles, however, remains to be studied because of the high correlation between exposure throughout the first 3 years of life.

Environmental tobacco smoke (ETS) and respiratory health in children

Environmental tobacco smoke (ETS) is a major risk factor for poor lung health in children. Although parental smoking is the commonest source of ETS exposure to children, they are also exposed to ETS in schools, restaurants, public places and public transport vehicles. Apart from containing thousands of chemicals, the particle size in the ETS is much smaller than the main stream smoke, and therefore has a greater penetrability in the airways of children. Exposure to ETS has been shown to be associated with increased prevalence of upper respiratory tract infections, wheeze, asthma and lower respiratory tract infections. Even developing fetuses are exposed to ETS via the umbilical cord blood if the mother is exposed to tobacco smoke. The placenta also does not offer any barrier to the penetration of ETS into the fetus. The immune system in these babies is more deviated toward the allergic and asthmatic inflammatory phenotype and therefore makes them more prone to develop asthma later in life. An increased awareness of the harmful effects of ETS on children's health is warranted.

Alpha-1-antitrypsin and complement component C7 are involved in asthma exacerbation

Asthma is the most common chronic disorder in childhood and asthma exacerbation is an important cause of childhood morbidity and hospitalization. Allergic responses are known to be biased toward T-helper type 2 in asthmatics; however, the pathogenesis of asthma is not simple, and our understanding of the disease mechanism remains incomplete. The aim of the present study was to identify protein expression signatures that reflect acute exacerbation of asthma. Plasma was taken twice from pediatric asthmatic patients, once during asthma exacerbation and once during a stable period. Plasma was also taken from healthy children as a control. The protein profiles of plasma during asthma exacerbation were analyzed by 2-DE and 49 spots were differentially expressed during asthma exacerbation. Thirty-eight of the spots were successfully identified by MALDI-TOF MS. Proteins up- or down-regulated during asthma exacerbation were involved in responses to stress and pathogens, in the complement and coagulation cascades, and in acute-phase responses. Among the differentially expressed proteins, up-regulation of alpha-1-antitrypsin and complement component C7 was confirmed by nephelometry and ELISA. Our present results suggest that protease inhibitors and complement components may be involved in asthma exacerbation, and plasma level of alpha-1-antitrypsin may be a potential biomarker for asthma.

Indoor ultrafine particles and childhood asthma: exploring a potential public health concern

Exposure to airborne particulate matter has a negative effect on respiratory health in both children and adults. The ultrafine fraction of particulate air pollution is of particular interest because of its increased ability to cause oxidative stress and inflammation in the lungs. We reviewed the literature, and to date findings suggest that ultrafine particles (UFPs) may play an important role in triggering asthma symptoms. Furthermore, we believe that indoor UFP exposures may be particularly important because people spend the majority of their time indoors where sources of these contaminants are often present. While several epidemiological studies have examined the respiratory effects of ambient UFP exposures, the relationship between indoor UFP exposures and childhood asthma has yet to be examined in clinical or epidemiological studies. However, the portable instrumentation necessary to conduct such investigations is increasingly available, and we expect that this issue will be addressed in the near future. Therefore, the aim of this article is to provide a general review of UFP toxicity as related to childhood asthma in order to draw attention to a potentially important public health concern.

PRACTICAL IMPLICATIONS

A number of indoor sources of ultrafine particles (UFPs) have been identified, but the health effects of indoor UFP exposures remain largely unexplored. The potential respiratory effects of such exposures seem most concerning because these particles are known to cause oxidative stress and inflammation in the lungs. Subsequently, indoor UFP exposures may contribute to the exacerbation of asthma symptoms in susceptible individuals. This paper provides a review of UFP toxicity as related to childhood asthma, and to date evidence suggests that further investigation into the respiratory effects of indoor UFP exposures is warranted.

Environmental tobacco smoke exposure: prevalence and mechanisms of causation of infections in children

BACKGROUND AND OBJECTIVES

Environmental tobacco smoke (ETS) exposure is probably one of the most important public health hazards in our community. Our aim with this article is to (1) review the prevalence of ETS exposure in the United States and how this prevalence is often measured in practice and (2) summarize current thinking concerning the mechanism by which this exposure may cause infections in young children.

METHODS

We conducted a Medline search to obtain data published mainly in peer-reviewed journals.

RESULTS

There is still a very high prevalence of ETS exposure among US children ranging from 35% to 80% depending on the method of measurement used and the population studied. The mechanism by which ETS may be related to these infections is not entirely clear but may be through suppression or modulation of the immune system, enhancement of bacterial adherence factors, or impairment of the mucociliary apparatus of the respiratory tract, or possibly through enhancement of toxicity of low levels of certain toxins that are not easily detected by conventional means.

CONCLUSIONS

The prevalence of ETS exposure in the United States is still very high, and its role in causing infections in children is no longer in doubt even if still poorly understood. Research, therefore, should continue to focus on the various mechanisms of causation of these infections and how to best reduce the exposure levels.

Association between neopterin in cord blood, urinary neopterin in early childhood and the development of atopic dermatitis, asthma and hay fever

It is generally accepted that the increased prevalence of atopic disease is due to a disturbed balance of T-helper (Th)1/Th2-type immunity. Upon stimulation by the Th1-type cytokine interferon (IFN)-gamma, human monocytes/macrophages release large amounts of neopterin. Thus, the determination of neopterin concentrations is an indirect measure of the levels of IFN-gamma and allows us to monitor Th1-type immune response. We evaluated whether neopterin concentrations in the neonatal cord blood could be a valuable marker predicting atopic disease in early childhood and whether there is a difference in actually determined urinary neopterin concentrations in children with and without atopic disease. Five hundred and five children born during 1997-1999 were enrolled, with cord blood neopterin data available at birth. The International study of asthma and allergies in childhood (ISAAC) questionnaire was used to assess the prevalence of wheezy bronchitis (asthma), atopic dermatitis and allergic rhinitis. Morning urinary samples were collected and urinary neopterin concentration was measured by high-pressure liquid chromatography. By the average age of 6 yr, the prevalence of atopic disease in the last 12 months was 31%. There was no significant correlation between cord blood and urinary neopterin concentrations at age 6 yr, and between cord blood neopterin and later atopic disease. Urinary neopterin concentrations were significant lower in children with a family history of atopic disease (p = 0.02). In this study, cord blood neopterin concentration was not a predictor for atopic disease in early childhood. Family history of atopic disease was associated with lower urinary neopterin levels at age 6 yr, which might mirror a Th1/Th2 imbalance.

Adding salmeterol to an inhaled corticosteroid reduces allergen-induced serum IL-5 and peripheral blood eosinophils

BACKGROUND

Adding a long-acting beta(2)-agonist to inhaled corticosteroids results in better symptomatic asthma control than increasing the dose of inhaled corticosteroids.

OBJECTIVE

Investigating whether adding the long-acting beta(2)-agonist salmeterol to the inhaled corticosteroid fluticasone propionate has an effect on allergen-induced allergic inflammation in asthma.

METHODS

Bronchial allergen challenges were performed in 26 patients with allergic asthma, pretreating them with a single dose of either fluticasone/salmeterol (100/50 microg) or fluticasone alone (100 microg), in a double-blind, randomized, cross-over design. Sputum and serum markers of bronchial inflammation were measured after allergen challenge, as well as lung function parameters. Primary outcomes were sputum eosinophil numbers and eosinophil cationic protein.

RESULTS

Asthmatic responses after allergen challenge were significantly reduced after pretreatment with fluticasone/salmeterol relative to fluticasone alone. Sputum inflammatory markers after allergen challenge were not significantly affected by fluticasone/salmeterol pretreatment. By contrast, serum IL-5 was significantly reduced (geometric mean serum IL-5 [SEM]: 0.5 [0.3] vs 1.1 [0.3] pg/mL 1 hour and 0.6 [0.3] vs 1.1 [0.3] pg/mL 6 hours after challenge with fluticasone/salmeterol vs fluticasone alone pretreatment, respectively; P values < .05). Also, peripheral blood eosinophils were significantly reduced (geometric mean number x 10(6)/L [SEM]: 172 [0.1] vs 237 [0.1] at 6 hours and 271 [0.1] vs 351 [0.1] at 24 hours with fluticasone/salmeterol vs fluticasone alone pretreatment, respectively; P < .05).

CONCLUSION

Adding salmeterol to fluticasone reduces allergen-induced serum IL-5 and peripheral blood eosinophils. This phenomenon may contribute to the improved clinical outcomes that result from adding a long-acting beta(2)-agonist to inhaled corticosteroids.

TNF-308 modifies the effect of second-hand smoke on respiratory illness-related school absences

RATIONALE

Exposure to second-hand smoke (SHS) has been associated with increased risk of respiratory illness in children including respiratory illness-related school absences. The role of genetic susceptibility in risk for adverse effects from SHS has not been extensively investigated in children.

OBJECTIVE

To determine whether the tumor necrosis factor (TNF) G-308A genotype influences the risk for respiratory illness-related school absences associated with SHS exposure.

METHODS

Incident school absences were collected, using an active surveillance system, between January and June 1996, as part of the Air Pollution and Absence Study, a prospective cohort study nested in the Children's Health Study. Buccal cells and absence reports were collected on 1,351 students from 27 elementary schools in California.

MEASUREMENTS AND MAIN RESULTS

Illness-related school absences were classified as nonrespiratory and respiratory illness-related, which were further categorized into upper or lower respiratory illness-related absences based on symptoms. The effect of SHS exposure on respiratory illness-related absences differed by TNF genotype (p interaction, 0.02). In children possessing at least one copy of the TNF-308 A variant, exposure to two or more household smokers was associated with a twofold risk of a school absence due to respiratory illness (relative risk, 2.13; 95% confidence interval, 1.34, 3.40) and a fourfold risk of lower respiratory illness-related school absence (relative risk, 4.15; 95% confidence interval, 2.57, 6.71) compared with unexposed children homozygous for the common TNF-308 G allele.

CONCLUSIONS

These results indicate that a subgroup of genetically susceptible children are at substantially greater risk of respiratory illness if exposed to SHS.

Risk factors for community-associated methicillin-resistant Staphylococcus aureus infections in an outbreak of disease among military trainees in San Diego, California, in 2002

An outbreak of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) skin infections was observed in a population of U.S. military trainees in the summer of 2002. A questionnaire was developed and administered to 206 trainees, 22 of whom had MRSA infections. Factors associated with infection were described by multivariable logistic regression modeling and included having a roommate in training with a prior skin infection (odds ratio [OR] = 3.44) or having a family member or friend who worked in a health care setting (OR = 2.79). Previous antibiotic use, hospitalization, or health problems were not associated with MRSA infection. This outbreak of MRSA skin infections in an otherwise-healthy, well-defined, military population provided an opportunity to describe risk factors for CA-MRSA which may help focus prevention efforts in this and other communities.

Environmental prevention in atopic eczema dermatitis syndrome (AEDS) and asthma: avoidance of indoor allergens

Indoor allergens represent an important precipitating factor for both asthma and atopic eczema dermatitis syndromes (AEDS). There is also accumulating evidence that sensitization to those allergens is associated with the onset of atopic disorders. Patients with AEDS present aeroallergen-specific T-cell responses associated with worsening of symptoms when exposed to specific aeroallergens. Furthermore, application of indoor allergens to the skin of patient with AEDS induces a local eczematous response in one-third of these patients. Exposure to high concentrations of mite allergens in early infancy have been demonstrated to be a risk factor for developing atopic dermatitis during the first 3 years of life. Moreover, a clear dose-response relationship has been documented between mite exposure and disease activity. Primary prevention of AEDS by avoiding indoor allergen exposure has been proved to be effective only when allergenic foods have also been avoided. Mite allergen avoidance in infants with AEDS and food allergy may however, prevent mite sensitization and the onset of asthma. Indoor allergen avoidance has been demonstrated to be effective in the majority of studies performed in patients with established AEDS. Negative results may be explained either by individual susceptibility variation, by long duration of disease with the consequent irreversible pathological changes in the target tissue or by exposure to allergens outside the house. Education of the patients and public consciousness of the problems are crucial for the efficacy of indoor allergen avoidance in allergic diseases.