The pattern of atopic sensitization is associated with the development of asthma in childhood

Asthma, allergy, and IgE levels in NYC head start children

BACKGROUND

Among preschool-age children in New York City neighborhoods with high asthma hospitalization rates, we analyzed the associations of total immunoglobulin E (IgE), specific IgE to common indoor allergens, and allergy symptoms with asthma.

METHODS

Parents of children in New York City Head Start programs were asked to complete a questionnaire covering demographic factors, health history (including respiratory conditions), lifestyle, and home environment. Children's serum samples were analyzed for total IgE and specific IgE antibodies to cockroach, dust mite, mouse, and cat allergens by immunoassay. Logistic regression was used to model the association between asthma and IgE, controlling for age, gender, ethnicity/national origin, BMI, parental asthma, smokers in the household, and allergy symptoms (e.g., runny nose, rash).

RESULTS

Among 453 participating children (mean age 4.0+/-0.5 years), 150 (33%) met our criteria for asthma. In our multivariable logistic regression models, children with asthma were more likely than other children to be sensitized to each allergen, to be sensitized to any of the four allergens (OR=1.6, 95% CI 1.0-2.6), or to be in the highest quartile of total IgE (OR=3.1, 95% CI 1.5-6.4). Allergy symptoms based on questionnaire responses were independently associated with asthma (OR=3.7, 95% CI 2.3-5.9).

CONCLUSIONS

Among preschool-aged urban children, asthma was associated with total IgE and sensitization to cat, mouse, cockroach, and dust mite allergens. However, allergy symptoms were more prevalent and more strongly associated with asthma than was any allergen-specific IgE; such symptoms may precede elevated specific IgE or represent a different pathway to asthma.

Indoor allergens and microbial bio-contaminants in homes of asthmatic children in central Taiwan

Indoor allergens and microbial bio-contaminants play a significant role in asthma symptoms. The aim of the study was to determine levels of house dust mite allergens, bacterial endotoxin, and fungal beta-glucan in homes of 120 asthmatic children in central Taiwan. Dust samples from 120 mattresses (67 double-sided) were analyzed for house dust mite allergens (Der p 1, Der f 1, and Blo t 5), endotoxin, and beta-glucan. Pillows (n = 118) were analyzed for house dust mite allergens only. Kitchen dust samples were analyzed for the cockroach allergen, Bla g 1. Blo t 5 was detected in 9.3% pillows and 82.2% mattresses, Der p 1 in 95.8% pillows and 93.2% mattresses, and Der f 1 in 82.2% pillows and 83.1% mattresses. Geometric mean levels (95% confidence interval) of endotoxin and beta-glucan in mattresses were 108.4 Eu/mg (81.4-144.2) and 25.2 microg/g (22.7-28.0), respectively. House dust mite allergens and endotoxin levels were significantly lower on the bamboo side of 67 mattresses, compared to the inner sprung mattress side. Geometric mean of kitchen Bla g 1 was 0.61 U/g (95% CI: 0.43-0.85). Given the presence of Der p 1, Der f 1 and Blo t 5 in central Taiwan, it is advised to measure allergens of all three house dust mite species to obtain a true index of allergen exposure. Bamboo sides of mattresses had significantly lower house dust mite allergens and endotoxin levels.

IL13 variants are associated with total serum IgE and early sensitization to food allergens in children with atopic dermatitis

Increased total and specific serum immunoglobulin E (IgE) levels are common characteristics of atopic diseases and their basal production is proposed to be under strong genetic control. Interleukin 13 (IL13) variants have been consistently associated with total serum IgE levels in white populations with a strongest association in non-atopics. The aim of this study was to test the IL13 p.R130Q and c.1-1111C>T variants in children with atopic dermatitis (AD) for associations with total serum IgE and early sensitization to common food and inhalant allergens and with asthma. We included 453 children with AD [participants of the Early Treatment of the Atopic Child (ETAC) study] that were followed from the age of 12-24 months for 3 yr. Total and specific IgE were determined at four time points. We genotyped the IL13 p.R130Q and c.1-1111C>T variants by melting curve analysis. In children up to 4 yr of age, the 130Q allele was related to slightly higher total IgE levels compared to heterozygotes and 130R homozygotes. More importantly, both IL13 variants were significantly associated with sensitization to food allergens, with most significant results for sensitization to egg (p = 0.0001). Although early sensitization to hen's egg represents a strong risk factor for subsequent sensitization to inhalant allergens and asthma, the investigated IL13 variants were not associated with these phenotypes at the age of 48-60 months. In summary IL13 variants contribute to elevated levels of total serum IgE in young atopic children and are strongly associated with sensitization to food allergens, particularly to hen's egg. These findings suggest that IL13 variants play a major role not only in non-cognate but also in allergen specific IgE synthesis.

What have we learnt from ISAAC phase III in the Asia-Pacific rim?

PURPOSE OF REVIEW

International Study of Asthma and Allergies in Childhood (ISAAC) phase III had provided a worldwide map of epidemiology of asthma and allergic diseases, as well as the changes in prevalence rate of these diseases when compared to data obtained in phase I. The wide variations of environmental factors and ethnic background in Asia provide excellent opportunities for research into the environmental and genetic determinants of asthma and allergies. This review summarizes important lessons learnt from ISAAC phase III results from Asia on asthma and allergy.

RECENT FINDINGS

ISAAC phase III provided epidemiological evidence of the wide variation and increasing prevalence of asthma and allergy in many Asian countries. When compared to other regions of the world, Asia has a relatively lower prevalence of asthma and allergic diseases. Comparative studies of populations of the same ethnic group living in different environments reveal striking disparity in prevalence of asthma and allergic diseases. The established risk factors could not explain the secular trend and variations of asthma prevalence in different Asian countries. Further research is needed in this rapidly changing region of Asia in order to identify the protective or risk factors associated with the development of asthma.

SUMMARY

ISAAC phase III provides standardized data on the prevalence and burden of asthma and allergy in the Asia-Pacific region. Further research is needed to reveal the underlying factors responsible for the wide variations in disease manifestations in the region.

The role of indoor allergens in the development of asthma

PURPOSE OF REVIEW

Asthma prevalence has markedly increased over the past 30 years. Although atopy and exposure to environmental allergens are known to exacerbate asthma, recent literature supports a causal role of indoor allergens in disease development.

RECENT FINDINGS

High-risk birth cohorts continue to point to atopy as the main risk factor for developing asthma. Exposure to perennial allergens has also been linked to the development of asthma, though with less consistency. Intervention at the level of allergen exposure and allergic immune response is promising.

SUMMARY

The current model of atopic asthma, the predominant phenotype, incorporates genetic and environmental factors in the development of disease. Although genetic factors are less malleable, the environmental component lends itself to analysis and modification.For many, the development of asthma starts with allergen exposure leading to atopic sensitization and subsequent disease. Several studies support the progression from exposure to sensitization with the potential of extremely high levels of exposure leading to tolerance. Likewise, the progression from atopy to asthma is well documented,especially in genetically predisposed children. Recent intervention trials confirm these findings and begin to show promise for the prevention of asthma by interrupting the allergen exposure==>allergen sensitization==>atopic asthma pathway.

[Atopy and asthma]

Numerous studies have shown an association between the development of allergic sensitization and asthma. On the population level the strength of this association is variable and depends on the gross national income (GNI) of a country. The higher the GNI is, the stronger is the association between atopy and asthma. The development of a perennial sensitization to indoor allergens such as house dust mites, cat and dog plays is a strong risk factor for a chronic asthma course over childhood years. Likewise, a strong sensitization to perennial allergens in adolescence contributes to asthma progression over puberty. Therefore, early and repeated allergy tests are warranted since they are predictors of the prognosis of these patients.

Allergy prevention starts before conception: maternofetal transfer of tolerance protects against the development of asthma

BACKGROUND

Allergy prevention must start early because environmental exposures during pregnancy and young life determine disease risk.

OBJECTIVE

In this study we analyzed whether prevention can start even earlier before conception by transfer of immunologic tolerance from the mother to the offspring preventing the offspring from having asthma.

METHODS

BALB/c mice were orally tolerized with ovalbumin before conception by means of oral application of antigen. The offspring of tolerized and naive mothers were immunized with ovalbumin at 6 weeks and 4 months of age and analyzed in our murine asthma model.

RESULTS

Although the offspring of naive mothers had an asthma-like phenotype, the offspring of tolerized mice were completely protected, even when immunized as late as 8 months after birth. Critically involved in the tolerance transfer was allergen-specific IgG, levels of which were increased in the sera of the mother, fetus, and pup and breast milk. FcRn(-/-) mice, which cannot transport IgG through the placenta, transferred tolerance to the offspring only when the missing diaplacental IgG transfer was compensated by IgG transfer through breast milk from tolerant mothers but not when weaned by naive wet nurses. Inhibition of IFN-gamma, produced by memory T cells in the offspring, abrogated the protective effect of maternal tolerance, demonstrating a crucial role for IFN-gamma in the maintenance of allergen-specific tolerance.

CONCLUSION

Our data show that maternal immunologic memory has a significant and persistent effect on the immune response of the offspring.

House dust mite allergens in domestic homes in Cheonan, Korea

House dust mites produce inhalant allergens of importance to allergic patients. We measured the major group 1 allergens, Der p 1 and Der f 1, from the house dust mites Dermatophagoides pteronyssinus and Dermatophagoides farina, respectively in 100 randomly selected domestic homes from Cheonan, Korea. Dust samples were collected by vacuuming from the living room floor and 1 mattress in each home. Der p 1 and Der f 1 were measured by double monoclonal ELISA. Der p 1 levels were very low, with geometric mean levels for floors and mattresses being 0.11 microgram/g (range: 0.01-4.05) and 0.14 microgram/g (range: 0.01-30.0), respectively. Corresponding levels of Der f 1 were higher, 7.46 microgram/g (range: 0.01-262.9) and 10.2 microgram/g (range: 0.01-230.9) for floors and mattresses, respectively. D. farinae appears to be the dominant house dust mite in Cheonan.

Anti-cockroach and anti-mouse IgE are associated with early wheeze and atopy in an inner-city birth cohort

BACKGROUND

The relationships between cockroach and mouse allergen exposure, anti-cockroach and anti-mouse IgE, and wheeze, rhinitis, and atopic dermatitis in children as young as age 3 years are of public health importance but have not been thoroughly evaluated.

OBJECTIVE

We hypothesized that inner-city children might have anti-cockroach and anti-mouse IgE by age 3 years, and their presence would be associated with respiratory and atopic symptoms.

METHODS

Children were followed prospectively from birth through age 3 years (n = 404). Residential levels of cockroach and mouse allergens, sera levels of anti-cockroach and anti-mouse IgE, and parental report of wheeze, rhinitis, and atopic dermatitis were measured.

RESULTS

The odds of early wheeze were significantly higher among children who had IgE to cockroach (odds ratio [OR], 3.3; 95% CI, 1.8-6.2), mouse (OR, 4.6; 95% CI, 2.3-9.0), or both (OR, 9.7; 95% CI, 3.4-27.3). The odds of rhinitis or atopic dermatitis were also higher among children with IgE to cockroach, mouse, or both. Higher IgE class to cockroach and mouse was associated with wheeze and atopic dermatitis (tests for trend, P < .002).

CONCLUSIONS

Children age 2 to 3 years who have anti-cockroach and anti-mouse IgE are at increased risk of wheeze and atopy. Moreover, a dose-response relationship was found between higher IgE class and increased prevalence of wheeze, rhinitis, or atopic dermatitis. These findings indicate the importance of reducing exposure to cockroach and mouse allergens for susceptible children.

Symptoms to pollen and fruits early in life and allergic disease at 4 years of age

BACKGROUND

The predictive value of reported early symptoms to pollen or fruits on later allergic disease is unclear. Our aim is to evaluate if symptoms to pollen and/or to fruits early in life are associated with allergic disease and sensitization to pollen at 4 years.

METHODS

The study included 3619 children from the Barn (Children), Allergy, Milieu, Stockholm, Epidemiology project (BAMSE) birth cohort. Reported symptoms of wheeze, sneeze or rash to birch, grass or weed, symptoms (vomiting, diarrhea, rash, facial edema, sneeze, or wheeze) to fruits including tree-nuts at 1 or 2 years of age, and definitions of asthma, rhinitis and eczema at 4 years were derived from questionnaire data. Sensitization to pollen allergens was defined as allergen-specific IgE-antibodies to any pollen (birch/timothy/mugwort) > or =0.35 kU(A)/l.

RESULTS

At 1 or 2 years of age, 6% of the children were reported to have pollen-related symptoms, 6% had symptoms to fruits, and 1.4% to both pollen and fruits. Children with symptoms to both pollen and fruits at 1 or 2 years of age had an increased risk for sensitization to any pollen allergen at age 4 (OR(adj) = 4.4, 95% CI = 2.1-9.2). This group of children also had a substantially elevated risk for developing any allergic disease (asthma, rhinitis, or eczema) at 4 years irrespective of sensitization to pollen (OR(adj) = 8.6, 95% CI = 4.5-16.4).

CONCLUSIONS

The prevalence of reported symptoms to pollen and fruits is very low in early childhood. However, children with early symptoms to both pollen and fruits appear to have a markedly elevated risk for allergic disease.

Prenatal exposure to household pets influences fetal immunoglobulin E production

BACKGROUND

Early life pet exposure may protect against allergic sensitization during childhood. Few studies have evaluated the effect of prenatal pet exposure on potential neonatal markers of allergic risk.

OBJECTIVE

The aim of this study was to investigate whether maternal exposure to pets affects cord blood IgE levels in a population-based, general risk, ethnically mixed birth cohort.

METHODS

Pet keeping during pregnancy was ascertained from women residing in a defined area of Wayne County Michigan and recruited from five staff model obstetric clinics. Maternal venous blood was analysed for total and allergen-specific IgE along with cord blood total IgE from 1049 infants.

RESULTS

Compared with infants from households with no cats or dogs kept indoors during pregnancy, infants whose homes had either cats or dogs had significantly reduced mean cord IgE levels [0.34 IU/mL (95% CI 0.30-0.38) vs. 0.24 IU/mL (0.20-0.27), P=0.025]. Similar effects were apparent in cat-only households [0.21 IU/mL (0.16-0.27), P=0.020] and dog-only households [0.24 IU/mL (0.19-0.29), P=0.045]. There was no effect on results when excluding mothers who reported avoiding pets due to allergy-related concerns.

CONCLUSION

Mothers with either cats or dogs in their home during pregnancy deliver children with lower cord blood IgE levels compared with mothers who do not live with these pets, supporting the hypothesis that pet exposure influences immune development in a manner that is protective for atopy and is operant even before birth.

Expired nitric oxide and airway reactivity in infants at risk for asthma

BACKGROUND

Family histories of atopy, as well as histories of atopic dermatitis and food allergy, are important risk factors for an infant to have asthma. Although atopic sensitization appears to contribute to the development of asthma, it is unclear when the airways become involved with the atopic process and whether airway function relates to the atopic characteristics of the infant.

OBJECTIVE

We sought to evaluate whether atopic infants without prior episodes of wheezing have increased expired nitric oxide (eNO) levels and heightened airway reactivity.

METHODS

Infants with eczema were recruited, and atopic status was defined by specific IgE levels to foods or aeroallergens and total IgE levels. eNO, forced expiratory flow at 75% exhaled volume (FEF(75)), and airway reactivity to inhaled methacholine were measured in sedated infants. Airway reactivity was quantified by using the provocative concentration to decrease FEF(75) by 30%.

RESULTS

Median age for the 114 infants evaluated was 10.7 months (range, 2.6-19.1 months). Infants sensitized to egg or milk compared with infants sensitized to neither egg nor milk had lower flows (FEF(75): 336 vs 285 mL/s, P < .003) and lower lnPC(30) (mg/mL) provocative concentrations to decrease FEF(75) by 30% (-0.6 vs -1.2, P < .02) but no difference in eNO levels. Infants with total serum IgE levels of greater than 20 IU/mL had higher eNO levels compared with infants with IgE levels of 20 IU/mL or less (14.6 vs 11.2 ppb, P < .023) but no difference in forced flows or airway reactivity.

CONCLUSIONS

Our findings suggest that atopic characteristics of the infant might be important determinants of the airway physiology of forced expiratory flows, airway reactivity, and eNO.

Incremental prognostic factors associated with cow's milk allergy outcomes in infant and child referrals: the Milan Cow's Milk Allergy Cohort study

BACKGROUND

The prognosis for many children with cow's milk allergy (CMA) is remission within 3 years, and the clinical parameters that predict duration of disease have not been measured incrementally.

OBJECTIVE

To prospectively determine prognostic predictors of tolerance in a random cohort of referrals using CMA workup outcomes as covariates and tolerance as the status variable in a duration model of CMA.

METHODS

The 2001-2006 Milan Cow's Milk Allergy Cohort (MiCMAC) enrolled children referrals using double-blind, placebo-controlled food challenges (DBPCFCs) as study end points (confirmation of CMA; onset of tolerance). The Cox regression model was used to analyze all clinical factors that contributed to tolerance. Covariates analyzed were skin, gastrointestinal, and respiratory symptoms; history and demographics at presentation; age at diagnosis and DBPCFC outcomes; sensitization (skin and serum) by cow's milk protein fractions; sensitization to other food and inhalant allergens; total IgE levels; specific IgE concentrations for cow's milk protein fractions, other ingestants, and aeroallergens; and threshold doses at DBPCFC. Sensitization and DBPCFC were performed at 6-month intervals.

RESULTS

A total of 112 infants were enrolled (mean [SD] age, 13.85 [9.84] months), and 59 achieved tolerance (mean [SD] age when tolerance was achieved, 27.58 [11.81] months). On univariate analysis, asthma and/or rhinitis at presentation was an independent predictor of persistence (hazard ratio [HR], 2.19; 95% confidence interval [CI], 1.26-3.82). On multivariate analysis, predictors of persistence were a fresh milk wheal diameter increment of 1 mm (HR, 1.18; 95% CI, 1.07-1.31) and a positive skin prick test result with soy (HR, 6.99; 95% CI, 1.56-31.25).

CONCLUSIONS

This is the first study, to our knowledge, to identify incremental biological predictors of delayed tolerance to cow's milk in children that should be integrated into DBPCFC schedules for CMA in infants.

Sensitization to inhalant allergens between 4 and 8 years of age is a dynamic process: results from the BAMSE birth cohort

BACKGROUND

There is limited knowledge of the development of IgE-antibody levels over time in childhood, with respect to persistency and co-sensitization to specific inhalant allergens.

METHODS

Data from 2033 children participating in the BAMSE birth cohort was used. Background factors and clinical parameters were obtained and IgE antibody (ab) levels to eight common airborne allergens were measured (>or=0.35 kU(A)/L) when the children were 4 and 8 years of age.

RESULTS

Between 4 and 8 years the proportion of children sensitized to any of the inhalant allergens tested increased from 15% to 25%. At 4 years IgE-ab to birch and cat dominated, whereas at the age of 8, there was a considerable increase in the proportion of sensitization to timothy and dog. Except for mites and moulds, IgE-ab levels to all aeroallergens increased significantly between 4 and 8 years among those already sensitized at 4. Transient sensitization to inhalant allergen was uncommon. Furthermore, sensitization to birch pollen at 4 years increased the risk for becoming sensitized to timothy, cat and dog later in life. Such an association was not observed among those sensitized primarily to animal dander.

CONCLUSIONS

There is a prominent process of sensitization at pre-school age to inhalant allergens, and in Northern Europe sensitization to birch pollen early in life seems to be important for this process. Such a process has a probable impact on the development of allergic disease in the growing child.

Age at first introduction of cow milk products and other food products in relation to infant atopic manifestations in the first 2 years of life: the KOALA Birth Cohort Study

OBJECTIVES

Scientific evidence is scarce about timing of solid-food introduction and its association with the development of atopy. We aimed to evaluate any associations between the introduction of cow milk products/other solid food products and infant atopic manifestations in the second year of life, taking into account reverse causation.

METHODS

Data from 2558 infants in an ongoing prospective birth cohort study in the Netherlands were analyzed. Data on the main determinants (introduction of cow milk products and other food products), outcomes (eczema; atopic dermatitis [United Kingdom Working Party criteria]; recurrent wheeze; any sensitization; sensitization against cow milk, hen egg, peanut, and at least 1 inhalant allergen), and confounders were collected by repeated questionnaires at 34 weeks of gestation and 3, 7, 12, and 24 months postpartum. Information on sensitization was gathered by venous blood collections performed during home visits at age 2. Analyses were performed by multiple logistic regression analyses.

RESULTS

More delay in introduction of cow milk products was associated with a higher risk for eczema. In addition, a delayed introduction of other food products was associated with an increased risk for atopy development at the age of 2 years. Exclusion of infants with early symptoms of eczema and recurrent wheeze (to avoid reverse causation) did not essentially change our results.

DISCUSSION

Delaying the introduction of cow milk or other food products may not be favorable in preventing the development of atopy.

Use of Phadiatop Infant in diagnosis of specific sensitization in young children with wheeze or eczema

Wheezing and eczema are common symptoms in young children and it is important to disclose sensitization for correct management. The objective of this study was to assess the diagnostic values of Phadiatop Infant, an in vitro test for graded determination of immunoglobulin E (IgE) antibodies to food and inhalant allergens. One-hundred and forty-nine children (median age 1.4 yr) with symptoms of wheezing (51%) eczema (28%) or a combination of both (21%) were classified as atopic or non-atopic based on case history, atopic history, physical examination and determination of IgE antibodies. The clinical performance of Phadiatop Infant was evaluated for 145 children against this classification in a blinded manner to the allergist. Fifty-one children were classified as atopic of which Phadiatop Infant identified 49. Ninety-four were non-atopic of which the test identified 90. This resulted in a sensitivity of 96%, a specificity of 96%, a positive and a negative predictive value of 94% and 98%, respectively. Logistic regression showed that probability had to be assessed as atopic increased with increasing Phadiatop Infant values. These results suggest that Phadiatop Infant can be recommended as an adjunct to the clinical information in the differential diagnosis on IgE-mediated allergy in young children. The test thus provides an opportunity for early correct diagnosis and identification of subjects at risk for whom intervention may be necessary.

Clinical assessment of asthma progression in children and adults

Asthma is a heterogeneous disorder with a variable course, characterized by episodes of cough, wheezing and shortness of breath, reversible airflow limitation, and bronchial hyperresponsiveness. It begins early in life in many subjects with intermittent symptoms occurring with viral respiratory tract infections. Over time, and in genetically susceptible children (those with an atopic predisposition), the disease becomes more persistent with symptoms occurring in the absence of respiratory tract infections. Children with persistent wheezing are eventually diagnosed with asthma, with those at greatest risk having developed allergic sensitization early in life. Among children with asthma, some will have lifelong asthma with active symptoms and progressive loss of lung function over time, whereas other children will undergo asthma remission in adolescence. Once in remission, the disease may remain quiescent, or it may relapse in midadult life. This review focuses on studies that have enhanced our understanding of the progression of asthma from infancy to adulthood. Studies evaluating progressive loss of lung function, the best-studied measure of asthma progression, are also reviewed, followed by a brief discussion of whether asthma progression can be modified by inhaled glucocorticoid therapy.

Lack of eosinophilia can predict remission in wheezy infants?

BACKGROUND

Early wheezing in infants is a potential risk factor for persistence of asthma into adulthood. Moreover, a personal or familial history of atopy are risk factors associated with persistence of pre-existing wheezing during childhood. However, their relative importance remains unclear.

OBJECTIVES

Firstly to determine the critical thresholds of common biological markers of atopy in wheezy infants associated with persistence of wheezing into childhood and secondly to rank these biological markers together with clinical parameters according to the strength of their association with wheezing persistence.

METHODS

A cohort of infants less than 30 months old with recurrent wheezing was established in order to assess severity of respiratory symptoms and to look for the presence of atopy. At the age of 6 years, they were re-evaluated regarding remission of wheezing over the previous 12-months period.

RESULTS

Data were available for 219 subjects. In 27% of them, wheezing persisted at 6 years of age. Critical biological thresholds associated with the risk of wheezing persistence were: (1) a blood eosinophilia count >or=470/mm(3) (defining eosinophilia), and (2) a total serum IgE level >or=45 IU/mL (defining elevated IgE) during infancy. A multiple component factorial analysis identified a dimension associating eosinophilia, elevated IgE and allergic sensitization on the one hand with persistent wheezing at 6 years of age on the other (lambda=0.15). According to a segmentation analysis, the main discriminative parameter of wheezing persistence was eosinophilia. Thus a lack of eosinophilia alone could account for 91% of infants in remission, and when combined with absence of allergic sensitization, remission was correctly discriminated in 96.9% of the study population.

CONCLUSION

Our data strongly suggest that the lack of eosinophilia in wheezy infants without ongoing infection could predict future remission of wheezing in a large majority of cases.

Correlation between spirometry and impulse oscillometry in children with asthma

AIM

In certain patients, such as young children or individuals with cerebral palsy or severe mental retardation, it is difficult to perform forced expiratory manoeuvres to measure expiratory flow volume. In such cases, we could evaluate obstructive lung disease through the measurement of airway resistance instead of expiratory flow volume.

METHODS

In this study, we evaluated the correlation of Impulse Oscillometry (IOS) parameters with spirometry values and peak expiratory flow rate (PEFR) measurements to give coherence to IOS recordings in lung function exploration. Total serum IgE levels, total eosinophil counts and specific IgE levels were measured in 48 children with asthma and 66 control subjects, aged 7-15 years of age. IOS, spirometry and PEFR measurements were performed, as well as methacholine challenge. We further analyzed the correlations in atopic asthma, atopic control, nonatopic asthma and nonatopic control groups.

RESULTS

FEV(1) and PEFR showed a significant correlation with impedance and resistance (R) at 5, 10, 20 and 35 Hz, both in atopic asthmatic and in atopic control children. FVC also showed a correlation with impedance and R at 10, 20 and 35 Hz, both in atopic asthmatic and atopic control children. FEF(25-75%) did not show a correlation with resistances.

CONCLUSION

FEV(1), FVC and PEFR were significantly correlated with IOS parameters, in both asthmatic and control subjects, especially for atopic children. IOS could be used as a suitable measure of lung function when spirometry and PEF cannot be performed.

Validity of MAST-CLA for diagnosis of arthropod allergy using receiver operating characteristic (ROC) analysis

Many allergists are currently focusing on the development of new diagnostic tools, and are attempting to improve both the sensitivity and specificity. A multiple allergen simultaneous test-chemiluminescent assay (MASTCLA) is one of the most popular diagnostic tools used in the Republic of Korea. However, there remains controversy among allergists with regard to the cut-off point for a positive result. The present study was conducted in order to determine the validity of MAST-CLA as compared with that of the skin prick test, with particular emphasis on arthropod allergens, on the basis of percentage agreement rates and kappa-values, and also to suggest the optimal positive cutoff points using receiver operating characteristic (ROC) curves. The study was conducted with 97 subjects (54 men, 43 women). Optimal individual cut-off points were calculated as follows; class II for Dermatophagoides farinae, class I for Dermatophagoides pteronyssinus, and trace for a cockroach mix. These findings suggest that attempting to apply optimal individual cut-off points will be a good way of improving diagnostic tests, particularly MAST-CLA.

Early predictors for developing allergic disease and asthma: examining separate steps in the 'allergic march'

BACKGROUND

Sensitization and symptoms of allergic disease are strongly correlated, but little is known about the early clinical precursors of the development of allergen sensitization in childhood. The aim of this study was to identify these predictors, and to examine separately the effect of early sensitization on subsequent wheeze, asthma, rhinitis and eczema.

METHODS

In the Childhood Asthma Prevention Study, children with a family history of asthma were assessed for allergen sensitization, total serum IgE, wheeze, asthma, eczema and rhinitis at ages 18 months and 5 years. To examine predictors, at 18 months, for subsequent sensitization, children who were non-sensitized at 18 months and had data on sensitization at 5 years were investigated, n=375. To examine the predictors, at age 18 months, of subsequent onset of symptoms, children who did not have wheeze, asthma, eczema or rhinitis at 18 months were followed-up at 5 years, n=177.

RESULTS

Among children who were non-sensitized at age 18 months, the presence of eczema [adjusted relative risk (aRR), 1.67, 95% confidence interval (CI) 1.20-2.33], but not wheeze, asthma or rhinitis, was an independent predictor of the onset of sensitization by age 5 years. Among children who were asymptomatic at age 18 months, sensitization to any allergen at 18 months was an independent predictor for the presence of wheeze (aRR 2.41, 95% CI 1.28-4.55), asthma (aRR 4.66, 95% CI 1.88-11.54) and rhinitis (aRR 1.77, 95% CI 1.08-2.90), but not for the development of eczema (aRR 0.78, 95% CI 0.23-2.64) at 5 years.

CONCLUSION

In non-sensitized children, eczema, but not wheeze, asthma or rhinitis is a predictor for subsequent development of sensitization. This suggests that early childhood eczema, rather than wheeze and rhinitis, may promote subsequent allergen sensitization and raises the possibility that early management of eczema may reduce the prevalence of sensitization in children.

IL-5 T-cell responses to house dust mite are associated with the development of allergen-specific IgE responses and asthma in the first 5 years of life

BACKGROUND

Allergen-specific T(H)2-like cytokine responses are considered to be important in sensitization and allergic diseases.

OBJECTIVE

To examine the profile of house dust mite (HDM) stimulated T-cell cytokines and their relationship to allergic disease in children over the period of the first 5 years of life.

METHODS

Subjects with a family history of asthma who were enrolled antenatally in the Childhood Asthma Prevention Study and had skin prick tests, clinical evaluation for asthma and eczema, and in vitro assessment of lymphocyte cytokine responses to HDM extract performed at ages 18 months (n = 281), 3 years (n = 349), and 5 years (n = 370). IL-13 at 3 and 5 years and IL-5, IL-10, and IFN- gamma at 18 months, 3 years, and 5 years were measured by ELISA.

RESULTS

House dust mite-specific cytokine responses increased with age for all cytokines except IFN-gamma. HDM-specific IL-5 responses at 3 years and 5 years were significantly positively related to skin prick test positivity at 5 years. IL-5 responses at 5 years were also significantly related to asthma at 5 years. Other HDM-specific cytokine responses were not related to asthma or eczema at 5 years. Responses were not altered by a HDM avoidance intervention.

CONCLUSION

IL-5 responses to HDM, the dominant local inhalant allergen, are related to the expression of clinical illness at age 5 years.

CLINICAL IMPLICATIONS

The T-cell response to HDM, as reflected in IL-5 production, is acquired over the first years of life and may play a role in the expression of allergic airways disease.

Early-onset atopy is associated with enhanced lymphocyte cytokine responses in 11-year-old children

BACKGROUND

Early age at onset of atopy is associated with more severe asthma and increased airway responsiveness (AR); the underlying mechanism is unclear but may involve T cell responses.

OBJECTIVE

To test the hypothesis that enhanced T cell responses may be associated with early-onset atopy.

METHODS

In a longitudinal study, atopy was determined in infancy and at 6 and 11 years of age. Individuals were categorized as persistent infant-onset atopy (PIOA), early childhood-onset atopy (ECOA) and later childhood-onset atopy (LCOA). At 11 years of age, peripheral blood T cell cytokine responses, AR, exhaled nitric oxide (FE(NO)) and forced expiratory volume in 1 s were determined.

RESULTS

The age at onset of atopy was determined for 60 children, of whom 15 had PIOA, 24 had ECOA and 21 had LCOA. An additional 76 children who were never atopic were also included. T cell responses to house dust mite, including interleukin-5, -9, -10 and tumour necrosis factor alpha, were higher among children with PIA and ECOA, and lower in children with LCOA, P<0.05. In contrast, those children with LCOA or who were not atopic had the highest IL-10 response to PHA (P=0.014). Children with PIOA and ECOA, but not LCOA, had higher AR and FE(NO) compared with non-atopic children (P<0.05). The group with PIOA were more likely among the atopic children to be admitted to hospital for asthma (P<0.05) and also had lower %FEV(1) compared with non-atopic children (P=0.023).

CONCLUSIONS

Early age at sensitization is associated with enhanced T cell cytokine responses and indices of adverse asthma outcome. T cell cytokine responses might be programmed at the time of initial atopic sensitization.

Duration of allergic susceptibility in maternal transmission of asthma risk

PROBLEM

Asthma has its origins in early-life. Maternal, not paternal asthma is an important risk factor, but the mechanisms and the duration of the maternal effect are unknown.

METHOD OF STUDY

Offspring of asthmatic and normal mice were sensitized with ovalbumin (OVA) at 1, 3, 6 and 10 weeks of age, challenged with aerosolized OVA 2 weeks later and tested for airway hyperresponsiveness (AHR) and allergic airway inflammation (AI).

RESULTS

Offspring of asthmatic, but not normal, mothers showed AHR and AI after OVA sensitization at week 1. Similarly increased susceptibility to OVA was observed when sensitized at 3 or 6 weeks, although the magnitude diminished. Offspring sensitized at 10 and challenged at 12 weeks showed some AI but no AHR.

CONCLUSION

In offspring from asthmatic mothers increased allergic susceptibility persisted through the young adulthood, albeit with gradual decline, which suggests a long-lived but reversible skewing of the developing immune system.

Risk of developing asthma in young children with atopic eczema: a systematic review

BACKGROUND

It is commonly believed that the majority of infants and young children with early atopic eczema will develop asthma in later childhood. This belief is mainly based on cross-sectional population studies. Recent evidence suggests a more complex relationship between early eczema and asthma.

OBJECTIVE

This systematic review was conducted to assess the risk of developing asthma in children with atopic eczema during the first 4 years of life.

METHODS

A sensitive search was performed to identify all prospective cohort studies on the topic. By pooling the eligible reports, we calculated the risk of developing asthma at 6 years of age or older in children with atopic eczema in the first 4 years of life.

RESULTS

Thirteen prospective cohort studies were included, with 4 representing birth cohort studies and 9 representing eczema cohort studies. The pooled odds ratio for the risk of asthma after eczema, compared with children without eczema, in birth cohort studies was 2.14 (95% CI, 1.67-2.75). The prevalence of asthma at the age of 6 years in eczema cohort studies was 35.8% (95% CI, 32.2% to 39.9%) for inpatients and 29.5% (95% CI, 28.2% to 32.7%) for a combined group of inpatients and outpatients.

CONCLUSION

Although there is an increased risk of developing asthma after eczema in early childhood, only 1 in every 3 children with eczema develops asthma during later childhood. This is lower than previously assumed.

CLINICAL IMPLICATIONS

Our results may have important consequences for counseling patients with atopic eczema and their parents.

Aeroallergen sensitization in healthy children: racial and socioeconomic correlates

OBJECTIVE

Allergic sensitization is very prevalent and often precedes the development of allergic disease. This study examined the association of race with allergic sensitization among healthy children with no family history of atopy.

STUDY DESIGN

Two hundred seventy-five children, predominantly from lower socioeconomic strata, from Cincinnati, Ohio, ages 2 to 18 years without a family or personal history of allergic diseases, underwent skin prick testing to 11 allergen panels. The Pediatric Allergic Disease Quality of Life Questionnaire (PADQLQ) was used to examine the impact of sensitization on quality of life.

RESULTS

Thirty-nine percent of healthy children were sensitized to 1 or more allergen panels. Multivariate logistic regression showed increased risk among African-American children for any sensitization (OR, 2.17; [95% CI: 1.23, 3.84]) and sensitization to any outdoor allergen (OR, 2.96 [95% CI: 1.52, 5.74]). Eighty-six percent of children had PADQLQ scores of 1 or less (0 to 6 scale).

CONCLUSIONS

Allergic sensitization is prevalent even among children who do not have a personal or family history of asthma, allergic rhinitis, or atopic dermatitis and who have no evidence of current, even subtle effects from this sensitization on allergic disease-related quality of life. African-American children are at greater risk for presence of sensitization, especially to outdoor allergens.

Health Care Consequences of Cesarean Birth During the First 18 Months of Life

OBJECTIVE

Elective cesarean delivery is increasingly common. The potential effects of surgical delivery in an unselected sample of infants beyond the immediate neonatal period remain poorly defined.

METHODS

We carried out an 18-month follow-up of a population-based cohort of 8327 Hong Kong Chinese infants born in 1997. The main outcome measures were utilization of outpatient visits and hospitalizations, categorized by doctor-diagnosed causes as reported by parents.

RESULTS

Among term singleton infants, there was no association of cesarean (compared with vaginal) birth with subsequent hospital admission (adjusted odds ratio = 0.92; 95% confidence interval = 0.79-1.08) or with above versus below the median number of outpatient episodes (1.10; 0.96-1.26) in the first 18 months of life. There were weak positive associations with afebrile gastrointestinal, respiratory, skin and a few other conditions.

CONCLUSION

Cesarean birth is not associated with hospitalization or outpatient care overall during the first 18 months after adjustment for confounders. We cannot rule out isolated associations with minor morbidities.

Predicting the development of early skin test sensitization in offspring of parents with asthma

BACKGROUND

The direct causal relationship between skin sensitization and asthma are controversial until now and remains to be further researched. Our aim is to analyse the role of parental asthma in the development of skin sensitization in offspring.

MATERIALS AND METHODS

This study was performed among nuclear families (determined by index of asthma patients), and subjects included parents and offspring. Parents were subdivided into four phenotypes on the basis of skin sensitization (SPT+ or SPT-) and asthma status (AST+ or AST-) and offspring were subdivided into three age groups: 3-8, 9-14 and 15-20 years. The main tests included a standard questionnaire and skin prick tests.

RESULTS

Offspring's skin sensitization differed among parental phenotypes at all ages (P < 0.05). In the SPT+/AST-, SPT-/AST+ and SPT+/AST+ groups, offspring were significantly more likely to be allergic than the ones in SPT-/AST- group at 3-8 years. Offspring with at least one parent with asthma were significantly more likely to have positive skin prick test response than those with non-asthmatic parents at age 3-8 years and 9-14 years, but not at 15-20 years among offspring with allergic parents. Results were independent of asthma in the children and of the characteristics of atopy in the parents.

CONCLUSION

Parent asthma history is an independent risk factor for allergic sensitization in their offspring in a Chinese population.

Regulatory role of Peyer’s patches for the inhibition of OVA-induced allergic diarrhea

Intestinal allergic diseases are initiated by aberrant Th2-type immune responses, including elevation of IgE antibodies (Abs) and infiltration of eosinophils. However, little is known about the role of Peyer's patches (PP) in the control of allergic diseases. Using a mouse model for food allergy, we here show that mice lacking PP are more susceptible to disease development and show higher levels of antigen-specific IgE Abs than do PP-intact mice. In our study, we noted that high numbers of eosinophils infiltrated into the small intestine of PP-null mice. In contrast, the PP of intact mice contained regulatory CD4+CD25+ Foxp3+ T cells (Treg) that are known to produce high levels of IL-10, and inhibited the development of allergic diarrhea. PP-intact mice thus developed allergic diarrhea when treated with anti-CD25 or anti-IL-10 monoclonal antibody (mAb) in vivo. These studies demonstrate that PP, as the site where IL-10-producing Treg cells are created, mediate the mucosal regulatory network for the control of undesired allergic responses in the intestine.

Environmental and socio-demographic factors associated to asthma in adolescents in Rio de Janeiro, Brazil

Although asthma is of frequent occurrence, little is known about the factors associated with this disease in Brazil. We studied the association between asthma, environmental and socio-demographic factors in adolescents in Nova lguacu, Rio de Janeiro State. Cross-sectional study using the questionnaires about asthma and environmental factors from the International Study of Asthma and Allergies in Childhood (ISAAC). We performed bivariate analyses between asthma and the factors studied using prevalence ratio (PR), confidence intervals of 95% (95% Cl) and Chi-squared test. Factors associated to asthma in a bivariate analysis were studied using logistic regression and odds ratio (OR). We included 3,033 students, aged 13-14 yrs, selected from 37 schools. The prevalence of asthma was 13.1%. Being female (OR = 1.40; 95%Cl:1.11-1.77), the presence of a mother who smokes (OR = 1.32; 95%Cl:1.04-1.66), a cat in the domicile (OR = 1.32; 95%Cl:1.04-1.69), being the firstborn (OR = 1.34; 95%Cl:1.07-1.68), frequent use of paracetamol (OR = 1.45; 95%Cl: 1.15-1.84), the presence of rhinitis (OR = 5.15; 95%:3.89-6.82) and eczema (OR = 2.35; 95%Cl:1.73-3.19) were independently associated to asthma. Environmental and socio-demographic factors were associated to asthma in adolescents in Rio de Janeiro, irrespective of the presence of others allergic diseases. Interventions acting on these factors may decrease the occurrence of asthma in this population.

Comparison of patterns of allergen sensitization among inner-city Hispanic and African American children with asthma

BACKGROUND

Among Hispanics, the largest minority ethnic group in the United States, asthma prevalence is increasing, particularly in inner-city neighborhoods. Although allergen sensitization among asthmatic African Americans has been extensively studied, similar details are not available for Hispanic children.

OBJECTIVES

To examine patterns of allergen sensitization, including the association with illness severity, in asthmatic children overall and in Hispanic and African American children living in a socioeconomically disadvantaged area of New York City.

METHODS

A retrospective medical record review of asthmatic children attending a community hospital in the South Bronx area of New York City was performed. Information abstracted included demographics, asthma severity classification, reported exposures to indoor allergens, and results of allergy testing.

RESULTS

Among 384 children in the analysis, 270 (70.3%) were Hispanic and 114 (29.7%) were African American. Sensitization to indoor and outdoor allergens, respectively, did not differ between Hispanic (58.5% and 27.0%) and African American (58.8% and 32.6%) children. Allergen sensitization exhibited a direct, significant association with asthma severity for indoor allergens for the 2 ethnic groups combined and for Hispanics separately but not between asthma severity and outdoor allergens (P < .01). No correlation was found between self-reported allergen exposure and sensitization.

CONCLUSIONS

Patterns of allergen sensitization among inner-city Hispanic asthmatic children resemble those among African American children, a finding that is likely explained by the similarity in levels of environmental exposures. With the increasing prevalence of asthma among inner-city Hispanic children, skin testing should be used frequently for objective evaluation of asthma in this ethnic group.

[Assessing the risk of asthma in infants and pre-school children]

Childhood asthma is a heterogeneous inflammatory disease with several wheezing phenotypes (transient, atopic, nonatopic, and obese) and various clinical expressions of multifactorial origin. All forms, however, follow a similar course characterized by recurrent episodes of airway obstruction. Studies have shown that the onset of disease occurs early in life for the great majority of asthmatics, that airway inflammation and remodeling are present in schoolchildren with asthma, and that even infants with persistent wheezing present airway inflammation. The difficulty lies in the early identification of infants with recurrent wheezing who are at risk of suffering persistent asthma later in life. The Asthma Predictive Index, a simple tool validated in a longitudinal study, has been suggested for early identification of infants with recurrent wheezing who are at risk of developing asthma and whose lung function has undergone major irreversible damage during the first years of life.

Patterns of sensitization in infants and its relation to atopic dermatitis

Longitudinal studies in infant populations using validated diagnostic criteria of atopic dermatitis and sensitization are rarely reported, and disease definitions, testing procedures, age of study population and evaluation of objective markers vary between countries and studies. The objectives of this prospective birth cohort study were to investigate: (i) the prevalence, the cumulative incidence and the pattern of transient and persistent sensitization to common food- and aeroallergens in unselected infants, (ii) the association between sensitization and the development of atopic dermatitis (AD) and (iii) the association between selected perinatal risk factors with respect to AD and post-natal sensitization. During a one-year period a cohort of 562 unselected newborns was established and followed up at the age of 3, 6, 9, 12 and 18 months of age. At all time points infants were examined clinically and by histamine release (HR), total- and specific immunoglobulin E (IgE) and skin prick test (SPT). Sensitization ever to > or =1 allergen at 18 months of age was 59%, 50% and 6% using HR, IgE and SPT, respectively. A transient sensitization to > or =1 allergen was found in 47%, 42% and 4% and a persistent sensitization in 17%, 10% and 3%, respectively. Sensitization to environmental allergens was frequently observed in infancy when testing with HR and IgE. Results of SPT gave much lower frequencies. Reactivity to foods was more frequent than to aeroallergens. The dominant pattern was low-level transient sensitization. This is important to know when sensitization tests are used in the course of examination of infants with eczematous skin diseases. Specific definitions of sensitization like persistent reactivity, high-level sensitization and poly sensitization were clearly associated with AD. A maternal history of AD was a valuable tool in predicting AD in early infancy; a similar finding was less obvious with regard to post-natal sensitization. Cord-specific IgE and cord-HR positive reactivity did not prove better tools than cord-total IgE in predicting AD within the first 18 living months.

Sensitization to different pollens and allergic disease in 4-year-old Swedish children

BACKGROUND

Although the relationship between sensitization to different inhalant allergens in adolescents and adults has been intensively studied, information concerning sensitization in children is scarce in particular to pollens.

OBJECTIVES

In 4-year-old children to elucidate the pollen immunoglobulin (IgE) antibody profile (birch only, timothy only and combinations of three pollens (birch, timothy or mugwort) and to relate the results to other inhalant and food allergens, as well as the presence of allergic diseases.

METHODS

A total of 2551 4-year-old children belonging to a prospective birth cohort, which has been followed longitudinally (BAMSE), were investigated with respect to IgE antibodies to pollen and other inhalant and food allergens, and expression of allergic disease, based on questionnaire data.

RESULTS

Eleven percent (n=285) of the children were sensitized to pollen. Birch was the dominating cause of pollen sensitization (birch sensitization only, n=133); followed by timothy grass pollen (n=56) and a combination of two (n=64) or three (n=30) pollens. A remarkably high proportion of the children sensitized only to birch was also sensitized to other inhalant allergens. This was not seen for children sensitized only to timothy. The highest frequencies of IgE reactivity to food were found in the group of children sensitized to the combination of birch, timothy and mugwort pollen. Children sensitized to timothy only, exhibited symptoms of allergic disease significantly less frequently compared with children sensitized to birch only. Sensitization to birch pollen was found to be closely associated with rhinitis and eczema compared with asthma. The highest frequency of asthma and/or rhinitis and/or eczema was reported in children sensitized to at least two pollens.

CONCLUSION

Our results demonstrate that birch is the dominating source of pollen sensitization at the age of four in Sweden. This might associate with the pattern of sensitization to other inhalant and food allergens as well as influence on the expression of allergic disease in this particular age group.

The regulation of allergy and asthma

Allergic diseases and asthma are caused by exaggerated T-helper 2 (Th2)-biased immune responses in genetically susceptible individuals. Tolerance to allergens is a mechanism that normally prevents such responses, but the specific immunological events that mediate tolerance in this setting are poorly understood. A number of recent studies indicate that regulatory T cells (Tregs) play an important role in controlling such Th2-biased responses. Tregs involved in regulating allergy and asthma consist of a family of related types of T cells, including natural CD25+ Tregs as well as inducible forms of antigen-specific adaptive Tregs. Impaired expansion of natural and/or adaptive Tregs is hypothesized to lead to the development of allergy and asthma, and treatment to induce allergen-specific Tregs could provide curative therapies for these problems.

The prevalence of atopy in asthmatic children correlates strictly with the prevalence of atopy among nonasthmatic children

BACKGROUND

Because asthma preferentially burdens persons with atopy, atopy is simplistically considered a primary 'cause' of asthma. Yet at the population level, the percentage of asthma cases 'attributable' to atopy ranges from less than 10% to more than 60%. Seeking to understand the rationale for the variability of atopy-attributable cases of asthma, we systematically reviewed the results of our own previous epidemiological studies and several studies conducted by others in children.

METHODS

From each of the 37 random pediatric populations selected by a Medline search combining the key words 'IgE or skin tests or hypersensitivity, immediate' with 'epidemiological studies, cross-sectional, case-control, prevalence, longitudinal, epidemiology of asthma' (12 from our previous pediatric surveys and a further 25 reported from 19 studies in children), we extracted the population prevalence of asthma and atopy among asthmatic subjects and among the nonasthmatic part of the population.

RESULTS

No correlation was found between the prevalence of asthma (range 1.8-44.1%) and atopy (range 5.8-63.9%) in these 37 populations of children (r = 0.052, p = 0.761). Nevertheless, the prevalence of atopy among asthmatics strictly correlated with the prevalence of atopy in nonasthmatics (r = 0.900, p < 0.001, slope 1.364).

CONCLUSION

The prevalence of asthma and atopy varies worldwide and at various time points and independently undergoes the influence of powerful environmental factors. The almost perfect correlation we found between atopy in asthmatics and atopy in the nonasthmatic part of the childhood population shows that the prevalence of atopy in asthma depends on environmental factors that simultaneously induce atopy in asthmatic and nonasthmatic subjects.

Prediction of asthma in young adults using childhood characteristics: Development of a prediction rule

OBJECTIVE

To develop an easily applicable prediction rule for asthma in young adulthood using childhood characteristics.

METHODS

A total of 1,055 out of 1,328 members of a Dutch birth cohort were followed from 2 to 21 years of age. Univariate and multivariate logistic regression analyses were used to evaluate the predictive value of childhood characteristics on asthma at 21 years of age. A prognostic function was developed, and the area under the receiving operating characteristic (ROC) curve was used to estimate the predictive ability of the prognostic models.

RESULTS

Of the 693 responding subjects, 86 (12%) were diagnosed with asthma. Independent prognostic factors at ages 2 and 4 years were female gender (odds ratios (OR) 1.9 and 2.1; 95% confidence intervals (CI) 1.2-3.2 and 1.3-2.5), smoking mother (OR 1.6 and 1.6; CI 1.0-2.7 and 1.0-2.6), lower respiratory tract illness (OR 1.9 and 2.4; CI 1.0-3.6 and 1.4-4.0), and atopic parents (OR 2.1 and 1.9; CI 1.3-3.4 and 1.2-3.1). The predictive power of both models was poor; area under ROC curve was 0.66 and 0.68, respectively.

CONCLUSION

Asthma in young adulthood could not be predicted satisfactorily based on childhood characteristics. Nevertheless, we propose that this method is further tested as a tool to predict development of asthma.

The role of iNKT cells in development of bronchial asthma: a translational approach from animal models to human

The iNKT cell represents a unique T-lymphocyte sublineage that has been associated with a broad range of disease processes; including host defense against infectious disease, cancer immunity and allergic autoimmune diseases, such as asthma. Studies in both animal models and human subjects suggest that iNKT cells might significantly affect the course of asthma. This study discusses various aspects of iNKT cell function and how it might lead to an important therapeutic target in asthma (airway hyperreactivity).

Issues in design and implementation in an urban birth cohort study: the Syracuse AUDIT project

The Syracuse AUDIT (Assessment of Urban Dwellings for Indoor Toxics) project is a birth cohort study of wheezing in the first year of life in a low-income urban setting. Such studies are important because of the documented serious risks to children's health and the lack of attention and published work on asthma development and intervention in communities of this size. We studied 103 infants of mothers with asthma, living predominantly in inner-city households. Our study combines measurements of a large panel of indoor environmental agents, in-home infant assessments, and review of all prenatal and postnatal medical records through the first year of life. We found multiple environmental pollution sources and potential health risks in study homes including high infant exposure to tobacco smoke. The prevalence of maternal smoking during pregnancy was 54%; postnatal environmental tobacco smoke (ETS) exposure was nearly 90%. The majority (73%) of homes showed signs of dampness. Participants' lives were complicated by poverty, unemployment and single-parenthood. Thirty-three percent of fathers were not involved with their children, and 62% of subjects moved at least once during the study period. These socioeconomic issues had an impact on project implementation and led to modification of study eligibility criteria. Extensive outreach, follow up, and relationship-building were required in order to recruit and retain families and resulted in considerable work overload for study staff. Our experiences implementing the project will inform further studies on this and other similar populations. Future reports on this cohort will address the role of multiple environmental variables and their effects on wheezing outcome during the first year of life.

Timing of initial exposure to cereal grains and the risk of wheat allergy

OBJECTIVE

Early exposure to solid foods in infancy has been associated with the development of allergy. The aim of this study was to examine the association between cereal-grain exposures (wheat, barley, rye, oats) in the infant diet and development of wheat allergy.

METHODS

A total of 1612 children were enrolled at birth and followed to the mean age of 4.7 years. Questionnaire data and dietary exposures were obtained at 3, 6, 9, 15, and 24 months and annually thereafter. The main outcome measure was parent report of wheat allergy. Children with celiac disease autoimmunity detected by tissue transglutaminase autoantibodies were excluded. Wheat-specific immunoglobulin E levels on children reported to have wheat allergy were obtained.

RESULTS

Sixteen children (1%) reported wheat allergy. Children who were first exposed to cereals after 6 months of age had an increased risk of wheat allergy compared with children first exposed to cereals before 6 months of age (after controlling for confounders including a family history of allergic disorders and history of food allergy before 6 months of age). All 4 children with detectable wheat-specific immunoglobulin E were first exposed to cereal grains after 6 months. A first-degree relative with asthma, eczema, or hives was also independently associated with an increased risk of wheat-allergy development.

CONCLUSIONS

Delaying initial exposure to cereal grains until after 6 months may increase the risk of developing wheat allergy. These results do not support delaying introduction of cereal grains for the protection of food allergy.

Variation in the type I interferon gene cluster on 9p21 influences susceptibility to asthma and atopy

A genome-wide screen for asthma and atopy susceptibility alleles conducted in the Hutterites, a founder population of European descent, reported evidence of linkage with a short tandem repeat polymorphism (STRP) within the type I interferon (IFN) gene cluster on chromosome 9p21. The goal of this study was to identify variation within the IFN gene cluster that influences susceptibility to asthma and atopic phenotypes. We screened approximately 25 kb of sequence, including the flanking sequence of all 15 functional genes and the single coding exon in 12, in Hutterites representing different IFNA-STRP genotypes. We identified 78 polymorphisms, and genotyped 40 of these (in 14 genes) in a large Hutterite pedigree. Modest associations (0.003<P<0.05) with asthma, bronchial hyper-responsiveness (BHR), and atopy were observed with individual variants or genes, spanning the entire 400 kb region. However, pairwise combinations of haplotypes between genes showed highly significant associations with different phenotypes (P<10(-5)) that were localized to specific pairs of genes or regions of this cluster. These results suggest that variation in multiple genes in the type I IFN cluster on 9p22 contribute to asthma and atopy susceptibility, and that not all genes contribute equally to all phenotypes.

Exposure of the fetus and infant to hens' egg ovalbumin via the placenta and breast milk in relation to maternal intake of dietary egg

BACKGROUND

Maternally derived allergens may be transferred to the developing infant during pregnancy and lactation. However, it is not known how manipulation of environmental allergen levels might impact on this early-life exposure.

OBJECTIVE

To measure dietary egg allergen (ovalbumin (OVA)) in gestation-associated environments, in relation to maternal dietary egg intake.

METHOD

OVA was measured by allergen-specific ELISA in maternal blood collected throughout pregnancy, infant blood at birth (umbilical cord) and in breast milk at 3 months post-partum. Samples derived from pregnant women undergoing diagnostic amniocentesis at 16-18 weeks gestation who were not subject to any dietary intervention, and from pregnant women, with personal or partner atopy, randomized to complete dietary egg exclusion or an unmodified healthy diet before 20 weeks gestation as a primary allergy prevention strategy. Maternal dietary egg intake was monitored closely throughout the study period by diary record and serial measurement of OVA-specific immunoglobulin G concentration.

RESULTS

Circulating OVA was detected throughout pregnancy in 20% of women and correlated with both presence (P<0.001) and concentration (r=0.754, P<0.001) of infant OVA at birth (umbilical cord). At 3 months post-partum OVA was detected in breast milk samples of 35% women, in higher concentrations than measured in blood. Blood and breast milk OVA were not related to maternal dietary intake or atopic pre-disposition.

CONCLUSIONS

Rigorous dietary egg exclusion does not eliminate trans-placental and breast milk egg allergen passage. This early-life exposure could modulate developing immune responses.

When allergies complicate allergies

The 'allergic march' is a term used to describe an individual's progress from one clinical manifestation of allergy to another, with age. Not all sensitized children will join the allergic march, but it appears that individuals who do not join the allergic march have a greater risk of displaying symptoms of allergic disease in adulthood. Consequently, there is a need for early diagnosis of allergy in children. Immunoglobulin E (IgE) antibody quantification is increasingly used for this purpose. However, rather than making a diagnosis based on single positive IgE antibody results only, it may be more efficient to test a profile of airborne and food allergens and use the sum of IgE antibody concentrations > or =3.5 kUA/l in combination with the number of allergens that elicit positive results tests. Allergic diseases often co-exist in patients, and the combination of several exposures at a given time (the allergen load) is related to disease severity. Therefore, a reduction of the allergen load is a key to successful treatment.

Relationship between aeroallergen and food allergen sensitization in childhood

BACKGROUND

Previous studies measuring the prevalence of allergen sensitization have been relatively small and used small numbers of allergens. To effectively evaluate children with atopic disease, we need an accurate knowledge of which allergens are important.

OBJECTIVE

To measure the prevalence of sensitization within a large unselected birth cohort, to examine the associations between sensitization to different allergens and determine whether atopy can be defined by a small panel of allergens.

METHODS

The Avon Longitudinal Study of Parents and Children is a population-based birth cohort of 13,638 singletons surviving to 4 weeks of age. The cohort was skin tested at 7 years of age to house dust mite (Dermatophagoides pteronyssinus), grass pollens, cat, peanuts, mixed tree nuts and egg and one of three other panels: animal danders, foods or aeroallergens. Sensitization was defined as a weal diameter of > or =3 mm. The strength of associations between sensitization to different allergens was tested by calculating the odds ratio adjusted for sensitization to D. pteronyssinus and grass pollen and gender.

RESULTS

Valid data were obtained from 6412 singletons. Sensitization was most common to aeroallergens: grass pollens (8.5%), D. pteronyssinus (7.8%), cat (4.9%), D. farinae (3.6%), dog (2.7%), horse (1.4%), rabbit (1.4%). Of the foods tested, the most common sensitization was to peanut (1.4%) and mixed tree nuts (1.0%). More than 95% of subjects with sensitization to any of the 29 allergens tested were sensitized to one of grass, D. pteronyssinus or cat allergen. There were strong associations of multiple sensitizations both within and between different allergen classes (pollens, animals, foods, peanut and tree nuts).

CONCLUSIONS

Seven-year-old children in the UK are primarily sensitized to aeroallergens, but also to peanuts and tree nuts. There are strong associations between sensitization within allergen groups as well as between allergen groups. Further studies are required to observe whether similar associations are seen with clinical allergy to these allergens.

Immunostimulatory CpG oligonucleotides abrogate allergic susceptibility in a murine model of maternal asthma transmission

We tested the potential of CpG oligodeoxynucleotides (ODN) to reverse the increased susceptibility to allergic airways disease in neonatal mice in a model of maternal transmission of asthma risk. Offspring of OVA-sensitized and challenged BALB/c mother mice were subjected to an intentionally suboptimal sensitization protocol that has minimal effects on normal mice, but results in airway hyperresponsiveness (AHR) and airway inflammation (AI) in babies of asthmatic mother mice. We evaluated pulmonary function and AI in CpG- or control ODN-treated offspring. CpG treatment of neonates on day 4 of life prevents the AHR otherwise seen in this model (enhanced pause at 100 mg/ml methacholine: CpG, 0.9 +/- 0.1; ODN control, 3.8 +/- 0.6; n = 62; p < 0.005). It also prevented the development of AI, as evident in decreased bronchoalveolar lavage eosinophilia (CpG, 1.2 +/- 0.3%; ODN, 31.4 +/- 4.1%; n = 56; p < 0.005), diminished the severity of AI on histopathology, and resulted in lower IL-5 levels in bronchoalveolar lavage fluid. The effect of CpG persisted for at least 4-6 wk and was allergen independent. Treatment with CpG just before OVA aerosol challenge also prevented allergic responses. The data support the potential for immunomodulatory therapy with CpG in early life to reduce susceptibility to asthma.

High allergen exposure as a risk factor for asthma and allergic disease

The association between pet ownership in childhood and subsequent asthma and sensitization is very controversial. Intriguing, but contradictory, reports have caused considerable uncertainty in parents who wish to avoid asthma and allergic disease in their children. This article argues that high allergen exposure is a risk factor for asthma and allergic disease. It describes dispersal of pet allergens in society and critically assesses epidemiological studies regarding how early exposure to pet allergens affects subsequent immunoglobulin E-sensitization and allergic diseases. Additionally, this article evaluates the effects of allergen exposure in already sensitized subjects with asthma. Cat and dog allergens are ubiquitous in society and may induce sensitization and allergic symptoms in predisposed individuals, regardless of pet ownership. This, in combination with selection mechanisms for pet ownership in families with a history of allergic diseases, makes it difficult to study associations between early exposure to pets and subsequent allergic disease. Nevertheless, exposure to pet allergens worsens asthma in already sensitized children. Thus, it is clear that clinicians should advise sensitized asthmatics that avoidance of exposure to indoor allergens is an important element in the treatment of allergic disease.

Defining childhood atopic phenotypes to investigate the association of atopic sensitization with allergic disease

AIMS

Although atopic sensitization is common in childhood, its relationship to clinical allergic disease remains incompletely understood. We therefore sought to explore this relationship by defining sensitization based atopic phenotypes.

METHODS

Children were recruited at birth (n = 1456) and reviewed at 1, 2, 4 and 10 years. Skin prick testing (SPT) to common allergens was done at 4 (n = 980) and 10 years (n = 1036) with lung function (n = 981), bronchial challenge (n = 784) and serum IgE (n = 953) testing at 10. Atopic phenotypes were defined, by sensitization pattern, for children with SPT at both 4 and 10 years (n = 823).

RESULTS

Of phenotyped children, 68.0% were never atopic, 4.3% early childhood atopic (only atopic at age 4), 16.5% chronic childhood atopics (at 4 and 10 years) and 11.2% delayed childhood atopics (only at 10). Never atopics showed small but identifiable prevalence of allergic diseases such as asthma, eczema and rhinitis. Amongst allergen-sensitized subjects, aeroallergen predominated over food sensitization throughout childhood. Chronic childhood atopics showed highest prevalence of lifetime plus persistent wheeze, eczema and rhinitis, increased prevalence of aeroallergen sensitization, some evidence of persistent food sensitization, significantly greater cord IgE than never atopics (P = 0.006), plus higher total IgE (P < 0.001) and bronchial hyper-responsiveness (P < 0.001) at 10 years than other phenotypes.

CONCLUSION

A proportion of childhood eczema, rhinitis and asthma is nonatopic. The commonest childhood pattern of atopy is chronic sensitization, associated with early, persisting and clinically significant allergic disease. The currently accepted childhood 'Allergic March' may oversimplify the natural history of childhood atopy and allergic disease.