Trends in cutaneous sensitization in the first 18 years of life: results from the 1989 Isle of Wight birth cohort study

Natural course of pollen-induced allergic rhinitis from childhood to adulthood: A 20-year follow up

BACKGROUND

Allergic rhinitis (AR) is one of the most common chronic diseases worldwide. There are limited prospective long-term data regarding persistency and remission of AR. The objective of this study was to investigate the natural course of pollen-induced AR (pollen-AR) over 20 years, from childhood into early adulthood.

METHODS

Data from 1137 subjects in the Barn/Children Allergi/Allergy Milieu Stockholm Epidemiologic birth cohort (BAMSE) with a completed questionnaire regarding symptoms, asthma, treatment with allergen immunotherapy (AIT) and results of allergen-specific IgE for inhalant allergens at 4, 8, 16 and 24 years were analyzed. Pollen-AR was defined as sneezing, runny, itchy or blocked nose; and itchy or watery eyes when exposed to birch and/or grass pollen in combination with allergen-specific IgE ≥0.35kUA/L to birch and/or grass.

RESULTS

Approximately 75% of children with pollen-AR at 4 or 8 years had persistent disease up to 24 years, and 30% developed asthma. The probability of persistency was high already at low levels of pollen-specific IgE. The highest rate of remission from pollen-AR was seen between 16 and 24 years (21.5%); however, the majority remained sensitized. This period was also when pollen-specific IgE-levels stopped increasing and the average estimated annual incidence of pollen-AR decreased from 1.5% to 0.8% per year.

CONCLUSION

Children with pollen-AR are at high risk of persistent disease for at least 20 years. Childhood up to adolescence seems to be the most dynamic period of AR progression. Our findings underline the close cross-sectional and longitudinal relationship between sensitization, AR and asthma.

Prevalence and risk factors for allergic sensitization: 3 cross-sectional studies among schoolchildren from 1996 to 2017

Background

The prevalence of allergic sensitization and allergic diseases has increased for decades in Northern Europe, but recent studies are lacking.

Objective

We sought to study the prevalence trends of allergic sensitization, associated risk factors, and the association with asthma and allergic rhinitis (AR) among children in Northern Sweden.

Methods

Three cohorts of children aged 7 to 8 years participated in a skin prick test (SPT) with 10 airborne allergens in 1996, 2006, and 2017, with 2148, 1693, and 1762 participants tested, respectively, representing 87% to 90% of schoolchildren in the catchment communities. Adjusted Poisson regression was used to identify risk factors for allergic sensitization and the association with asthma and AR.

Results

The prevalence of any positive SPT response increased from 21% in 1996 to 30% in 2006 and remained at 30% in 2017 (P < .001). Sensitization to cat was the most common for all the years. The risk factor pattern for a positive SPT response was similar in all examinations, with positive and significant associations with a family history of allergy (risk ratio, 1.4-1.5) and negative and significant associations with having a cat at home (risk ratio, 0.7-0.8). The prevalence of physician-diagnosed asthma increased, but the association with allergic sensitization weakened. The opposite trends were found for AR-decreasing prevalence and strengthened association with allergic sensitization.

Conclusions

The prevalence of allergic sensitization increased from 1996 to 2006 but plateaued in the next decade, whereas the risk factor pattern remained stable. The diverging trends of associations between allergic sensitization and asthma and AR suggest secular trends in the clinical management of allergic diseases.

Sensitisation to Pollen Allergens in Children and Adolescents of Different Ancestry Born and Living in the Same Area

Background

Allergy can start at early ages, with genetic and environmental factors contributing to its development.

Aim

The study aimed to describe the pattern of sensitisation and allergy in children and adolescents of Spanish versus Moroccan ancestry but born in the same rural area of Spain.

Methods

Participants were children and adolescents (3–19 years) of Spanish or Moroccan descent, born in Blanca, Murcia (Spain). A detailed questionnaire was completed, and skin prick tests were performed to assess reactions to the most prevalent pollen allergens (O. europaea, P. pratense, S. kali, C. arizonica, P. acerifolia, A. vulgaris and P. judaica) plus molecular components Ole e 1 and Ole e 7. The association with ancestry was verified by studying participants’ parents.

Results

The study included 693 participants: 48% were aged 3–9 years and 52%, 10–19 years; 80% were of Spanish descent and 20% of Moroccan descent. Sensitisation to Olea europaea, Phleum pratense, Salsola kali and Cupressus arizonica were slightly higher in the Spanish group. The only significant differences were observed in sensitisation to Ole e 1 (p=0.02). Rhinitis, conjunctivitis, and rhinitis plus asthma were significantly higher in the Spanish group (p=0.03, p=0.02, p=0.007, respectively). The sensitisation pattern differed between Spanish and Moroccan parents, and between Moroccan parents and their children, but not between Spanish parents and their children.

Conclusion

Both environment and ancestry may influence sensitisation and symptoms. Although the environment seems to have a stronger influence, other factors may contribute to the differences in prevalence and in the clinical entities in people of Spanish versus Moroccan descent.

Moderate-to-severe lower respiratory tract infection in early life is associated with increased risk of polysensitization and atopic dermatitis: Findings from the CHILD Study

Background

Respiratory infections in infancy are associated with the development of allergic asthma and atopy. Delineating whether symptomatic infections are a marker of atopic predisposition or contribute to atopic development is important for preventive strategies. We hypothesized that early, severe lower respiratory tract infections (LRTIs) may be a risk factor for the development of atopic disease.

Objective

Our aim was to determine whether clinically defined, moderate-to-severe LRTIs in infancy are associated with the development of atopic dermatitis and allergic sensitization at preschool age.

Methods

LRTI timing and severity in the first 18 months of life was defined by using the Canadian Healthy Infant Longitudinal Development study questionnaires. Polysensitization and atopic dermatitis were determined by standardized skin prick testing and structured clinical assessments. Longitudinal associations between LRTI severity and clinical outcomes at ages 3 years and 5 years were determined by adjusted repeated measures generalized estimation equations.

Results

Moderate-to-severe LRTIs were associated with increased odds of polysensitization (odds ratio = 1.91 [95% CI = 1.16-3.15]; P = .014) and atopic dermatitis (odds ratio = 2.19 [95% CI 1.41-3.39]; P < .001) as compared with the odds in children with no history of LRTI in the first 18 months of life. The association between moderate-to-severe LRTI and polysensitization or atopic dermatitis remained robust after adjusting for sex; study site; breast-feeding duration; and mother, father, or both-parent atopy or asthma.

Conclusions

These results highlight severe infant LRTI as an important risk factor for allergic and atopic disease (ie, polysensitization and atopic dermatitis), and they suggest that this risk is independent of maternal in utero environment, both-parent history of asthma, and both-parent genetic predisposition.

The majority of children sensitized before school-age develop allergic disease before adulthood: a longitudinal population-based study

BACKGROUND

Allergic sensitization increases the risk of and asthma and allergic rhinitis, but the impact of age at onset of sensitization is less studied.

OBJECTIVE

To examine the cumulative incidence of asthma and rhinitis up to age 19 years in relation to age at onset of sensitization to airborne allergens.

METHOD

All children in grade one and two (median age 8 years) in two municipalities in Northern Sweden were invited to skin prick tests and a questionnaire about allergic diseases, and 88% participated. At ages 12 and 19 years the protocol was repeated, and n=1510 individuals participated in all three examinations. Specific IgE was collected in a random sample at age 19, n=770. Onset of sensitization was defined; ≤8 years, 8-12 years, 12-19 years, and never sensitized. Adjusted Poisson regression was utilized to calculate risk ratios.

RESULTS

At age 19, those sensitized ≤8 year had the highest risk of asthma (RR 4.68 (95%CI 3.14-6.97)) and rhinitis (RR 22.3 (95%CI 13.3-37.6)), and 84% had developed either asthma or rhinitis. The combination of sensitization ≤8 year and family history of allergic diseases rendered high risks for asthma (RR 10.6 (6.71-16.7)) and rhinitis (RR 36.3 (18.9-69.7). Individuals sensitized ≤8 year showed significantly highest level of sensitization, as judged by number of positive skin tests and titers of specific IgE.

CONCLUSION

The majority of individuals with sensitization ≤8 years developed asthma or rhinitis before young adulthood. The high level of sensitization in early sensitized contribute to the high incidence of allergic airway conditions.

Incidence and remission of aeroallergen sensitization in adults in Northern Finland: 15 years longitudinal study

Studies on the longitudinal changes in sensitization to aeroallergens in adult populations are sparse. The aim was to evaluate changes in sensitization to aeroallergens [birch, timothy, cat and house dust mite (HDM)] in an unselected adult population aged from 31 to 46 years. Data were gathered from a cohort of adults (Northern Finland Birth Cohort 1966) who had been skin prick tested (SPT) with birch, timothy, cat and HDM allergens at the age of 31 years and at age 46 (n = 5484 and 5373 respectively). Data from both time points were available for 3409 participants, who made up the cohort of the longitudinal study. The overall prevalence of sensitization to any of the selected allergens was 30.3% (n = 1661) in 31-year-olds and 30.7% (n = 1649) in 46-year-olds. In general, men were more sensitized (P < 0.001) and also had more polysensitization (P < 0.001) compared to women. In longitudinal sub-population incidence of sensitization was 7.1%. Birch was the most prevalent new sensitizer, however, the difference was not statistically significant when compared to cat. We conclude that new sensitization, demonstrated by positive findings in SPT, can still occur in middle age and this should be taken into account when managing allergic manifestations in adults as sensitization can be considered the first step in developing clinical allergy.

Male sex is strongly associated with IgE-sensitization to airborne but not food allergens: results up to age 24 years from the BAMSE birth cohort

Background

Up to half of the population in high-income countries has allergen-specific IgE antibodies. However, data regarding sex differences of IgE-sensitization from childhood to adulthood is limited.

Objective

To explore IgE-sensitization to common foods and airborne allergens in relation to sex over time in a population-based cohort followed up to young adulthood.

Methods

The Swedish population-based birth cohort BAMSE includes 4089 subjects who have been followed regularly with questionnaires and clinical investigations. A recent 24-year follow-up included 3069 participants (75%). Sera collected at 4, 8, 16 and 24 years were analyzed for IgE-antibodies to 14 common foods and airborne allergens.

Results

At 24 years sensitization to foods had decreased compared to previous follow-ups affecting 8.4%, while sensitization to airborne allergens was more common, affecting 42.2%. Male sex was associated with IgE-sensitization to airborne allergens at all ages (overall OR: 1.68, 95% CI 1.46–1.94) while there was no statistically significant association between sex and sensitization to food allergens (overall OR: 1.10, 95% CI 0.93–1.32). Levels of allergen-specific IgE did not differ significantly between males and females for any of the tested foods or airborne allergens at any age, following adjustment for multiple comparisons.

Conclusion

IgE-sensitization to airborne allergens increases with age up to young adulthood, whereas sensitization to food allergens seems to level off. Male sex is strongly associated with IgE-sensitization to airborne allergens from early childhood up to young adulthood. In contrast, there is little evidence for associations between sex and IgE-sensitization to foods.

Eczema phenotypes and risk of allergic and respiratory conditions in school age children

Background

Eczema phenotypes based on eczema onset and persistence might better identify groups prone to allergic and respiratory conditions than a binary definition of eczema. We examined the associations of childhood eczema phenotypes with allergic sensitization, allergy, asthma and lung function at school age.

Methods

This study among 4277 children was embedded in a multi-ethnic population-based prospective cohort study. Five eczema phenotypes (never, early transient, mid-transient, late transient, persistent) based on parental-reported physician-diagnosed eczema from age 6 months until 10 years were identified. At age 10 years, allergic sensitization was measured by skin prick tests, physician-diagnosed allergy and asthma by parent-reported questionnaires, and lung function by spirometry. Adjusted linear, logistic and multinomial regression models were applied.

Results

Compared with never eczema, all eczema phenotypes were associated with increased risks of asthma (odds ratios (OR) range (95% confidence interval): 2.68 (1.58, 4.57) to 11.53 (6.65, 20.01)), food and inhalant allergic sensitization (1.72 (1.25, 2.36) to 12.64 (7.20, 22.18)), and physician-diagnosed inhalant allergy (1.92 (1.34, 2.74) to 11.91 (7.52, 18.86)). Strongest effect estimates were observed of early and persistent eczema with the risk of physician-diagnosed food allergy (OR 6.95 (3.76, 12.84) and 35.05 (18.33, 70.00), respectively) and combined asthma and physician-diagnosed allergy (7.11 (4.33, 11.67) and 29.03 (15.27, 55.22), respectively). Eczema phenotypes were not associated with lung function measures.

Conclusion

Eczema phenotypes were differentially associated with risks of respiratory and allergic conditions in school-aged children. Children with early transient and persistent eczema might benefit from more intense follow-up for early identification and treatment of asthma and allergies.

Filaggrin mutations increase allergic airway disease in childhood and adolescence through interactions with eczema and aeroallergen sensitization

BACKGROUND

Filaggrin loss-of-function (FLG-LOF) mutations are an established genetic cause of eczema. These mutations have subsequently been reported to increase the risk of aeroallergen sensitization and allergic airway disease. However, it is unclear whether FLG variants require both eczema and aeroallergen sensitization to influence airway disease development long-term outcomes.

OBJECTIVE

To examine the effects of FLG-LOF mutations on allergic airway disease outcomes, with eczema and aeroallergen sensitization as intermediate variables, using the Isle of Wight birth cohort.

METHODS

Study participants were evaluated at ages 1, 2, 4, 10 and 18 years to ascertain the development of allergic diseases (eczema, asthma and allergic rhinitis) and aeroallergen sensitization (determined by skin prick tests). FLG-LOF mutations were genotyped in 1150 subjects. To understand the complex associations between FLG mutations, intermediate variables (eczema and aeroallergen sensitization) and airway disease, path analysis was performed.

RESULTS

There were significant total effects of FLG-LOF mutations on both asthma and allergic rhinitis at all ages as well as on aeroallergen sensitization up till 10 years old. In the filaggrin-asthma analysis, a direct effect of FLG-LOF mutations was observed on early childhood eczema (age 1 and 2 years) (relative risk (RR) 2.01, 95% CI: 1.74-2.31, P < .001), and all significant indirect pathways on asthma outcomes passed through eczema at these ages. In contrast, for the filaggrin-rhinitis model, FLG-LOF mutations exerted significant direct effects on early eczema as well as rhinitis at 10 years (RR 1.99; 95% CI: 1.72-2.29, P = .002).

CONCLUSION

FLG-LOF mutations are a significant risk factor for later childhood asthma and rhinitis. However, the pathway to asthma is only through early childhood eczema while a direct effect was observed for childhood rhinitis.

DNA methylation and allergic sensitizations: A genome-scale longitudinal study during adolescence

BACKGROUND

The presence of allergic sensitization has a major influence on the development and course of common childhood conditions such as asthma and rhinitis. The etiology of allergic sensitization is poorly understood, and its underlying biological mechanisms are not well established. Several studies showed that DNA methylation (DNAm) at some CpGs is associated with allergic sensitization. However, no studies have focused on the critical adolescence period.

METHODS

We assessed the association of pre- and postadolescence genome-wide DNAm with allergic sensitization against indoor, outdoor and food allergens, using linear mixed models. We hypothesized that DNAm is associated with sensitization in general, and with poly-sensitization status, and these associations are age- and gender-specific. We tested these hypotheses in the IoW cohort (n = 376) and examined the findings in the BAMSE cohort (n = 267).

RESULTS

Via linear mixed models, we identified 35 CpGs in IoW associated with allergic sensitization (at false discovery rate of 0.05), of which 33 were available in BAMSE and replicated with respect to the direction of associations with allergic sensitization. At the 35 CpGs except for cg19210306 on C13orf27, a reduction in methylation among atopic subjects was observed, most notably for cg21220721 and cg11699125 (ACOT7). DNAm at cg10159529 was strongly correlated with expression of IL5RA in peripheral blood (P-value = 6.76 × 10^-20 ). Three CpGs (cg14121142, cg23842695, and cg26496795) were identified in IoW with age-specific association between DNAm and allergic sensitization.

CONCLUSION

In adolescence, the status of allergic sensitization was associated with DNAm differentiation and at some CpGs the association is likely to be age-specific.

Atopic diseases and type I sensitization from adolescence to adulthood in an unselected population (TOACS) with focus on predictors for allergic rhinitis

BACKGROUND

While much is known on childhood atopic diseases, knowledge about persistence of atopic diseases from childhood to adulthood is limited. We therefore aimed to study the clinical course of atopic diseases and type I sensitization prospectively in an unselected cohort of adolescents followed into adulthood.

METHODS

A cohort of unselected 8th-grade school children (mean age 14 years) established in 1995 and followed up in 2010 were evaluated with questionnaire, clinical examination, skin prick tests and measurements of specific IgE.

RESULTS

The lifetime prevalence of atopic diseases was high and increased significantly from adolescence (31%) to adulthood (57%); particularly allergic rhinitis increased with an incidence rate of 17.5/1000 person-years. Childhood predictors for adult allergic rhinitis were atopic dermatitis, asthma and asymptomatic sensitization to pollen and house dust mite. Among those with asymptomatic sensitization in adolescence, 53%-78% developed allergic rhinitis in adulthood. Furthermore, type I sensitization increased significantly from adolescence to adulthood mostly due to increased sensitization to pollen. Type I sensitization was found mainly in those with allergic rhinitis. A high number of adults had oral allergy symptoms due to the high number of birch pollen allergic individuals.

CONCLUSION

Persistence of atopic diseases in adulthood is common, and a high proportion of the adult population is sensitized giving a high prevalence of allergic rhinitis. Many with asymptomatic sensitization in adolescence will develop allergic rhinitis in adult life. The focus should be on prevention of atopic diseases and sensitization already in childhood.

Association of Sensitization to Different Aeroallergens With Airway Function and Nasal Patency in Urban Children

PURPOSE

Children with sensitization to aeroallergens have decreased lung function and nasal patency. Our purpose was to determine the association of sensitization to different aeroallergens with airway function and nasal patency.

METHODS

Four hundred and eighty-six randomly selected 11 year-old children who lived in Seongnam City were examined. Serum specific immunoglobulin E (IgE) levels against 6 common allergens (Dermatophagoidesfarinae, birch, cat, dog, Japanese hop and Alternaria), impulse oscillometry (IOS) results for the evaluation of airway dysfunction, and acoustic rhinometry for the determination of nasal airway patency were obtained.

RESULTS

IOS indicated that children sensitized to Alternaria (n = 38, 7.8%) and dog dander (n = 69, 14.2%) had decreased lung function, based on resistance at 10 Hz (Rrs10; aβ = 0.0072; 95% CI, 0.017, 0.127; P = 0.010) and 1 Hz (Rrs1; aβ = 0.038; 95% CI, 0.001, 0.074; P = 0.042). Children sensitized to D. farinae (n = 281, 57.8%) had decreased post-decongestant nasal volume at 0 to 5 cm (aβ = -0.605; 95% CI, -1.005, -0.205; P = 0.003), but normal IOS results at all measured frequencies (P > 0.05). Increased serum eosinophil level was associated with Rrs1 (P = 0.007) and Rrs2 (P = 0.018) and post-decongestant nasal volume at 0 to 5 cm (aβ = -0.885; 95% CI, -1.331, -0.439; P < 0.001).

CONCLUSIONS

Sensitivity to specific aeroallergens, serum eosinophil count and total IgE level had different associations with upper and lower airway dysfunction in urban children.

Parental and child factors associated with inhalant and food allergy in a population-based prospective cohort study: the Generation R Study

The prevalence of allergic diseases in children is markedly increasing to epidemic proportions. The aim of this study is to describe the presence and examine associated parental and child characteristics of allergic sensitization and physician-diagnosed allergy in Dutch children at age 10 years. This study among 5471 children was performed in a population-based prospective cohort from fetal life onwards. Allergic sensitization was measured by skin prick tests. Physician-diagnosed allergy and parental and child characteristics were collected by questionnaires. In children aged 10 years, inhalant and food allergic sensitization was present in 32.2% and 7.1%, and physician-diagnosed inhalant and food allergy in 12.4% and 2.3%. Maternal and paternal history of allergy, eczema or asthma was associated with increased risks of physician-diagnosed inhalant allergy (aOR (95% CI) 1.44 (1.23-1.70) and 1.59 (1.30-1.94), respectively), but not with food allergy. Asthma and eczema ever at age 10 years were associated with increased risks of physician-diagnosed inhalant allergy (4.60 (3.55-5.96) and 2.42 (1.94-3.03), respectively). Eczema ever at age 10 years was associated with an increased risk of physician-diagnosed food allergy (5.78, 3.04-9.52), with the highest risk of cashew (7.36, 3.20-16.94) and peanut (5.58, 3.08-10.10) food allergy.Conclusions: We found strong effects of parental history of allergy, eczema or asthma on the presence of physician-diagnosed inhalant allergy in children at age 10 years. Eczema ever at age 10 years was a strong risk factor for the development of physician-diagnosed inhalant and food allergy. What is Known: • The prevalence of allergic diseases in children has markedly increased. • Early-life influences are critically important in the development of allergic diseases. What is New: • Maternal and paternal history of allergy, eczema or asthma is associated with increased risks of physician-diagnosed inhalant allergy but not with food allergy. • Eczema ever at age 10 years is associated with an increased risk of physician-diagnosed food allergy, with the highest risk for cashew and peanut food allergy.

Exposure amount and timing of solar irradiation during pregnancy and the risk of sensitization in children

BACKGROUND

Solar irradiation affects sensitization to aeroallergens and the prevalence of allergic diseases. Little is known, however, about how the time and amount of solar irradiation during pregnancy affects such risks in children. We aimed to find out how solar irradiation during pregnancy affects sensitization to aero-allergens and the prevalence of allergic diseases in children.

METHODS

This population-based cross-sectional study involved 7301 aged 6 years and aged 12 years children. Maternal exposure to solar irradiation during pregnancy was evaluated using data from weather stations closest to each child's birthplace. Monthly average solar irradiation during the second and third trimesters was calculated with rank by quartiles. Risks of allergic sensitization and allergic disease were estimated.

RESULTS

Relative to the first (lowest) quartile, the adjusted odds ratio (aOR) for allergic sensitization in the fourth (highest) quartile was lowest within solar irradiation during pregnancy months 5-6 (aOR = 0.823, 95% CI 0.720-0.942, p < 0.05). During months 9-10, the aOR for allergic sensitization for the fourth was higher than the first quartile of solar irradiation (aOR = 1.167, 95% CI 1.022-1.333, p < 0.05). Similar results were observed when solar irradiation was analyzed as a continuous variable during months 5 (aOR = 0.975, 95% CI 0.962-0.989, p < 0.001) and month 9 (aOR = 1.018, 95% CI 1.004-1.031, p = 0.003). Increased solar irradiation during months 7-8 increased the risk of asthma (aOR = 1.309, 95% CI 1.024-1.674, p = 0.032).

CONCLUSIONS

Maternal exposure to solar irradiation during the second trimester of pregnancy associated with reduced aeroallergen sensitization, whereas solar irradiation during the third trimester was related to increased sensitization to aeroallergens.

Epistasis between FLG and IL4R Genes on the Risk of Allergic Sensitization: Results from Two Population-Based Birth Cohort Studies

Immune-specific genes as well as genes responsible for the formation and integrity of the epidermal barrier have been implicated in the pathogeneses of allergic sensitization. This study sought to determine whether an epistatic effect (gene-gene interaction) between genetic variants within interleukin 4 receptor (IL4R) and filaggrin (FLG) genes predispose to the development of allergic sensitization. Data from two birth cohort studies were analyzed, namely the Isle of Wight (IOW; n = 1,456) and the Manchester Asthma and Allergy Study (MAAS; n = 1,058). In the IOW study, one interaction term (IL4R rs3024676 × FLG variants) showed statistical significance (interaction term: P = 0.003). To illustrate the observed epistasis, stratified analyses were performed, which showed that FLG variants were associated with allergic sensitization only among IL4R rs3024676 homozygotes (OR, 1.97; 95% CI, 1.27–3.05; P = 0.003). In contrast, FLG variants effect was masked among IL4R rs3024676 heterozygotes (OR, 0.53; 95% CI, 0.22–1.32; P = 0.175). Similar results were demonstrated in the MAAS study. Epistasis between immune (IL4R) and skin (FLG) regulatory genes exist in the pathogenesis of allergic sensitization. Hence, genetic susceptibility towards defective epidermal barrier and deviated immune responses could work together in the development of allergic sensitization.

Prevalence and longitudinal trends of food allergy during childhood and adolescence: Results of the Isle of Wight Birth Cohort study

BACKGROUND

The prevalence and time trends of food allergy change during childhood depending on the age of the child and the type of food.

OBJECTIVE

To study prevalence and longitudinal trends in food allergy from birth to 18 years in an unselected birth cohort in the Isle of Wight.

METHOD

Information on food allergy was collected at ages 1, 2, 4, 10 and 18 years from the Isle of Wight Birth Cohort (n = 1456). Skin prick testing (SPT) was performed at the age of 1 and 2 years in symptomatic children. At 4, 10 and 18 years of age, participants were tested to a panel of food and aeroallergens. Food allergy was diagnosed based on the criteria: symptoms suggestive of a typical IgE-mediated reaction and reaction <4 hours following exposure to a known food allergen. McNemar's test was used to determine significance of changes in prevalence over time.

RESULTS

The prevalence of food allergy remained relatively constant in early childhood (5.3%, 4.4% and 5.0% at 1, 2 and 4 years, respectively), with significant decline at 10 years (2.3%, P < .001 vs 4 years) followed by significant rise at 18 years (4%, P = .02 vs 10 years). Cow's milk (1.6%-3.5%) and egg (1.1%-1.4%) were the most common allergens in the first 10 years with peanut (1%) and tree nuts (0.5%) becoming more prevalent beyond 10 years. Fruit and wheat allergy were less common at 10 years, and shellfish and kiwi emerged during adolescence. The prevalence of food allergy plus positive SPT was 1.3%, 0.8%, 0.8%, 0.9% and 2.2% at 1, 2, 4, 10 and 18 years, respectively.

CONCLUSION

Food allergy is highly prevalent in infancy with partial resolution during late childhood. However, a number of children acquire new food allergy during adolescence resulting in a relatively higher prevalence at 18 years.

Duration and exclusiveness of breastfeeding and risk of childhood atopic diseases

BACKGROUND

Breastfeeding may have immune modulatory effects that influence the development of childhood allergic sensitization and atopic diseases. We aimed to examine the associations of breastfeeding with childhood allergic sensitization, inhalant or food allergy and eczema, and whether any association was affected by disease-related modification of the exposure or modified by maternal history of allergy, eczema, or asthma.

METHODS

This study among 5828 children was performed in a population-based prospective cohort from fetal life onwards. We collected information on duration (<2 months, 2-4 months, 4-6 months, and ≥6 months) and exclusiveness (nonexclusive vs exclusive for 4 months) of breastfeeding in infancy by postal questionnaires. At age 10 years, inhalant allergic sensitization and food-allergic sensitization were measured by skin prick tests, and physician-diagnosed inhalant and food allergy by a postal questionnaire. Data on parental-reported eczema were available from birth until age 10 years.

RESULTS

We observed no association of breastfeeding with any allergic sensitization, physician-diagnosed allergy, or combination of these outcomes. Shorter breastfeeding duration was associated with an overall increased risk of eczema (P-value for trend <.05). Nonexclusively breastfed children had an overall increased risk of eczema (adjusted odds ratio [95% confidence interval]: 1.11 [1.01, 1.23]), compared with children exclusively breastfed for 4 months. Risk period-specific sensitivity analyses, additional adjustment for ointment use for eczema at age 2 months, and cross-lagged modeling showed no consistent results for disease-related modification of the exposure. Results were not modified by maternal history of allergy, eczema, or asthma (lowest P-value for interaction=.13).

CONCLUSION

Shorter duration or nonexclusiveness of breastfeeding is associated with a weak overall increased risk of eczema but not allergic sensitization or physician-diagnosed allergy at age 10 years.

Allergenic food introduction and risk of childhood atopic diseases

BACKGROUND

The role of timing and diversity of allergenic food introduction in the development of childhood allergic sensitization and atopic diseases is controversial.

OBJECTIVE

To examine whether timing and diversity of allergenic food introduction are associated with allergic sensitization, allergy and eczema in children until age 10 years.

MATERIALS AND METHODS

This study among 5,202 children was performed in a population-based prospective cohort. Timing (age ≤6 months vs. >6 months) and diversity (0, 1, 2 and ≥3 foods) of allergenic food (cow's milk, hen's egg, peanut, tree nuts, soy and gluten) introduction were assessed by questionnaires at ages 6 and 12 months. At age 10 years, inhalant and food allergic sensitization were measured by skin prick tests, and physician-diagnosed inhalant and food allergy by questionnaire. Data on parental-reported physician-diagnosed eczema were obtained from birth until age 10 years.

RESULTS

Children introduced to gluten at age ≤6 months had a decreased risk of eczema (aOR (95% CI): 0.84 (0.72, 0.99)), compared with children introduced to gluten at age >6 months. However, timing of allergenic food introduction was not associated with allergic sensitization or physician-diagnosed allergy. Children introduced to ≥3 allergenic foods at age ≤6 months had a decreased risk of physician-diagnosed inhalant allergy (0.64 (0.42, 0.98)), compared with children not introduced to any allergenic food at age ≤6 months. However, diversity of allergenic food introduction was not associated with allergic sensitization, physician-diagnosed food allergy or eczema.

CONCLUSION

Neither timing nor diversity of allergenic food introduction was consistently associated with childhood allergic sensitization, allergy or eczema.

Windows of opportunity for tolerance induction for allergy by studying the evolution of allergic sensitization in birth cohorts

Allergic sensitization is a risk factor for developing IgE-mediated allergic diseases, which are a major cause of chronic illness world-wide. The introduction of allergen molecules to the field of allergy diagnostics has allowed dissecting the IgE response on a molecular level to pinpoint the specific disease-causing allergens. Studying birth cohorts is an essential tool for understanding the development and life course of allergy, enabling the possibility to design preventive strategies. Here we review the evolution of sensitization using data from some of the large European birth cohort studies. Differences and similarities between sensitization to food and various sources of inhalant allergens are discussed and allergen molecules of importance in early childhood predicting disease in adolescence are highlighted. Finally, we discuss windows of opportunity where intervention could be considered and address possible preventive strategies.

High incidence and persistence of airborne allergen sensitization up to age 19 years

BACKGROUND

Longitudinal population-based studies about the natural history of allergic sensitization are rare. The aim was to study incidence and persistence of airborne allergen sensitization up to young adulthood and risk factors for early and late onset of sensitization.

METHODS

All children aged 7-8 years in two municipalities in Northern Sweden were invited to a parental questionnaire and skin prick tests (SPTs) to ten airborne allergens, and 2148 (88%) participated. The protocol was repeated at age 11-12 and 19 years, and 1516 participated in all three examinations.

RESULTS

Prevalence of any positive SPT increased from 20.6% at age 7-8 years to 30.6% at 11-12 years, and 42.1% at 19 years. Animals were the primary sensitizers at age 7-8 years, 16.3%, followed by pollen, 12.4%. Mite and mold sensitization was low. Mean annual incidence of any positive SPT varied between 2.8 and 3.4/100 per year, decreased by age for animal, and was stable for pollen. Sensitization before age 7-8 years was independently associated with family history of allergy, OR 2.1 (95% CI 1.6-2.8), urban living, OR 1.9 (95% CI 1.2-2.9), and male sex, OR 1.3 (95% CI 1.0-1.7), and negatively associated with birth order, OR 0.8 (95% CI 0.7-1.0), and furry animals at home, OR 0.7 (95% CI 0.7-0.9). Incidence after age 11-12 years was associated only with family history of allergy. Multisensitization at age 19 years was significantly associated with early age at sensitization. Remission of sensitization was uncommon.

CONCLUSION

The increasing prevalence of allergic sensitization by age was explained by high incidence and persistence. After age 11-12 years, the factors urban living, number of siblings, and male sex lost their importance.

Dietary total antioxidant capacity in early school age and subsequent allergic disease

Background

Dietary antioxidant intake has been hypothesized to influence the development of allergic diseases; however, few prospective studies have investigated this association.

Objective

Our aim was to study the association between total antioxidant capacity (TAC) of the diet at age 8 years and the subsequent development of asthma, rhinitis and sensitization to inhalant allergens between 8 and 16 years, and to assess potential effect modification by known risk factors.

Methods

A total of 2359 children from the Swedish birth cohort BAMSE were included. Dietary TAC at age 8 years was estimated by combining information on the child's diet the past 12 months from a food frequency questionnaire with a database of common foods analysed with the oxygen radical absorbance capacity method. Classification of asthma and rhinitis was based on questionnaires, and serum IgE antibodies were measured at 8 and 16 years.

Results

A statistically significant inverse association was observed between TAC of the diet and incident sensitization to inhalant allergens (adjusted odds ratio: 0.73, 95% confidence interval: 0.55–0.97 for the third compared to the first tertile, P‐value for trend = 0.031). Effect modification by traffic‐related air pollution exposure was observed, with a stronger association between dietary TAC and sensitization among children with low traffic‐related air pollution exposure (P‐value for interaction = 0.029). There was no evidence for effect modification by GSTP1 or TNF genotypes, although these results should be interpreted with caution. No clear associations were observed between TAC and development of rhinitis or asthma, although a significant inverse association was observed for allergic asthma (OR_adj 0.57, 95% CI 0.34–0.94).

Conclusions and Clinical Relevance

Higher TAC of the diet in early school age may decrease the risk of developing sensitization to inhalant allergens from childhood to adolescence. These findings indicate that implementing an antioxidant‐rich diet in childhood may contribute to the prevention of allergic disease.

Maternal psychiatric symptoms during pregnancy and risk of childhood atopic diseases

BACKGROUND

Maternal psychiatric symptoms during pregnancy might affect the developing immune system and subsequent risk of childhood atopic diseases.

OBJECTIVE

Our aim was to examine the associations of maternal psychiatric symptoms during pregnancy with allergic sensitization, allergy and eczema in children until age 10 years.

METHODS

This study among 5205 children was performed in a population-based prospective cohort from foetal life onwards. We assessed maternal and paternal psychiatric symptoms (overall, depressive, anxiety) during pregnancy and at 36 months after delivery, and maternal psychiatric symptoms at 2 and 6 months after delivery using the Brief Symptom Inventory. Inhalant and food allergic sensitization were measured by skin prick tests, and physician-diagnosed inhalant and food allergy or eczema by questionnaires from birth until age 10 years. We used multivariate logistic regression, multinomial logistic regression or generalized estimating equation models where appropriate.

RESULTS

We observed no association of maternal psychiatric symptoms during pregnancy with allergic sensitization. Maternal overall psychiatric, depressive and anxiety symptoms during pregnancy were associated with an increased risk of inhalant allergy only (adjusted odds ratio (95% confidence interval) 1.96 (1.44, 2.65), 1.58 (1.25, 1.98) and 1.61 (1.27, 2.03), respectively, per 1-unit increase). Maternal overall psychiatric and anxiety symptoms during pregnancy were associated with an increased risk of eczema (1.21 (1.05, 1.39) and 1.15 (1.02, 1.29), respectively, per 1-unit increase). Effect estimates did not materially change when maternal psychiatric symptoms after delivery, or paternal psychiatric symptoms during pregnancy and after delivery were taken into account.

CONCLUSIONS AND CLINICAL RELEVANCE

Maternal psychiatric symptoms during pregnancy were associated with increased risks of childhood inhalant allergy and eczema, independent of maternal psychiatric symptoms after delivery and of paternal psychiatric symptoms.

The prevalence of atopic diseases and the patterns of sensitization in adolescence

BACKGROUND

Atopic diseases are among the most common chronic diseases in adolescents, and it is uncertain whether the prevalence of atopic diseases has reached a plateau or is still increasing. The use of the ISAAC (International Study of Asthma and Allergy in Childhood) questionnaire has provided comparable prevalence rates from many countries, whereas studies including clinical examinations and strict diagnostic criteria are scarce. We aimed to investigate the prevalence of atopic diseases, the pattern of sensitization, and comorbidities at 14 years in a prospective birth cohort.

METHODS

The children were examined eight times from birth to 14 years. Visits included questionnaire-based interviews, clinical examination, skin prick test, and specific IgE.

RESULTS

Follow-up rate at 14 years was 66.2%. The 12-month prevalence of any atopic disease was high (40.3%) mostly due to a high prevalence of rhinoconjunctivitis (32.8%), whereas the prevalence of asthma was 12.9% and of atopic dermatitis 8.1%. In children with at least one atopic disease, 60% were sensitized, while only 16% of those without atopic diseases were sensitized. The frequency of sensitization depended on the phenotype. Among children with rhinoconjunctivitis only, rhinoconjunctivitis with concomitant asthma or atopic dermatitis or both 62.5%, 81.5%, 70%, and 100%, respectively, were sensitized, whereas it was 7.7% and 33.3% of children with only asthma or atopic dermatitis.

CONCLUSION

The prevalence of rhinoconjunctivitis was high in adolescence. Children with rhinoconjunctivitis with and without comorbidities were frequently sensitized. Children with asthma without concomitant allergic rhinoconjunctivitis were rarely sensitized.

Usefulness of component resolved analysis of cat allergy in routine clinical practice

BACKGROUND

Cat allergy is of great importance, and its prevalence is increasing worldwide. Cat allergens and house dust mite allergens represent the major indoor allergens; however, they are ubiquitous. Cat sensitization and allergy are known risk factors for rhinitis, bronchial hyperreactivity and asthma. Thus, the diagnosis of sensitization to cats is important for any allergist.

METHODS

70 patients with positive skin prick tests for cats were retrospectively compared regarding their skin prick test results, as well as their specific immunoglobulin E antibody profiles with regard to their responses to the native cat extract, rFel d 1, nFel d 2 and rFel d 4. 35 patients were allergic to cats, as determined by positive anamnesis and/or nasal provocation with cat allergens, and 35 patients exhibited clinically non-relevant sensitization, as indicated by negative anamnesis and/or a negative nasal allergen challenge.

RESULTS

Native cat extract serology testing detected 100% of patients who were allergic to cats but missed eight patients who showed sensitization in the skin prick test and did not have allergic symptoms. The median values of the skin prick test, as well as those of the specific immunoglobulin E antibodies against the native cat extract, were significantly higher for allergic patients than for patients with clinically non-relevant sensitization. Component based diagnostic testing to rFel d 1 was not as reliable. Sensitization to nFel d 2 and rFel d 4 was seen only in individual patients.

CONCLUSION

Extract based diagnostic methods for identifying cat allergy and sensitization, such as the skin prick test and native cat extract serology, remain crucial in routine clinical practice. In our study, component based diagnostic testing could not replace these methods with regard to the detection of sensitization to cats and differentiation between allergy and sensitization without clinical relevance. However, component resolved allergy diagnostic tools have individual implications, and future studies may facilitate a better understanding of its use and subsequently may improve the clinical management of allergic patients.

Tetanus vaccination is associated with differential DNA-methylation: Reduces the risk of asthma in adolescence

BACKGROUND

Vaccinations have been suggested to be associated with increased risk of allergic diseases. Tetanus vaccination is one of the most frequently administered vaccines as a part of wound management and was also found to be associated with increased serum IgE levels. We hypothesized that the vaccination modifies the risk of allergic diseases through epigenetic changes such as DNA methylation.

METHOD

Data on tetanus vaccination between 10 and 18years of age was collected from a birth cohort established on the Isle of Wight UK in 1989. DNA methylation data were collected from individuals at different ages (at birth [n=30], age 10 [n=34], age 18 [n=245] and during pregnancy [n=121]) using the Illumina Infinium HumanMethylation450K array. Firstly, we performed an epigenome-wide screening to identify cytosine-phosphate-guanine sites (CpGs) associated with tetanus vaccination in 18-year-olds. Secondly, we tested their association with asthma, allergic sensitization, eczema, serum IgE and pulmonary lung function (FVC, FEV1, FEV1/FVC, and FEF25-75%). We then described changes in the methylation of the selected CpG sites over age, and by vaccination status.

RESULTS

Tetanus vaccination was found to be associated with decreased methylation of cg14472551 (p value 0.5×10^-5, FDR-adjusted p value 2.1×10^-4) and increased methylation of cg01669161 (p value 0.0007, FDR-adjusted p value 0.014). Both CpGs, in turn, were associated with decreased risk of asthma at 18years of age. Cg14472551 is located in an intron of KIAA1549L, whose protein binds to a B-cell commitment transcription factor; cg01669161 is located between an antisense regulator of the proteasome assembly chaperone PSMG3, and TFAMP1, a pseudogene. Increased methylation of cg01669161 was also associated with decreased serum IgE levels.

CONCLUSION

DNA methylation changes following tetanus vaccination may offer a novel prospect to explain a differential occurrence of asthma in adolescence.

Usefulness of component resolved analysis of cat allergy in routine clinical practice

Background

Cat allergy is of great importance, and its prevalence is increasing worldwide. Cat allergens and house dust mite allergens represent the major indoor allergens; however, they are ubiquitous. Cat sensitization and allergy are known risk factors for rhinitis, bronchial hyperreactivity and asthma. Thus, the diagnosis of sensitization to cats is important for any allergist.

Methods

70 patients with positive skin prick tests for cats were retrospectively compared regarding their skin prick test results, as well as their specific immunoglobulin E antibody profiles with regard to their responses to the native cat extract, rFel d 1, nFel d 2 and rFel d 4. 35 patients were allergic to cats, as determined by positive anamnesis and/or nasal provocation with cat allergens, and 35 patients exhibited clinically non-relevant sensitization, as indicated by negative anamnesis and/or a negative nasal allergen challenge.

Results

Native cat extract serology testing detected 100% of patients who were allergic to cats but missed eight patients who showed sensitization in the skin prick test and did not have allergic symptoms. The median values of the skin prick test, as well as those of the specific immunoglobulin E antibodies against the native cat extract, were significantly higher for allergic patients than for patients with clinically non-relevant sensitization. Component based diagnostic testing to rFel d 1 was not as reliable. Sensitization to nFel d 2 and rFel d 4 was seen only in individual patients.

Conclusion

Extract based diagnostic methods for identifying cat allergy and sensitization, such as the skin prick test and native cat extract serology, remain crucial in routine clinical practice. In our study, component based diagnostic testing could not replace these methods with regard to the detection of sensitization to cats and differentiation between allergy and sensitization without clinical relevance. However, component resolved allergy diagnostic tools have individual implications, and future studies may facilitate a better understanding of its use and subsequently may improve the clinical management of allergic patients.

Increase in Allergic Sensitization in Schoolchildren: Two Cohorts Compared 10 Years Apart

BACKGROUND

Time trends of incidence of allergic sensitization are unknown and recent trends of prevalence and risk factors are lacking.

OBJECTIVE

To estimate the incidence, prevalence, remission, risk factors, and time trends for allergic sensitization among schoolchildren followed from age 7 to 8 years to age 11 to 12 years.

METHODS

In 2006, all children in grades 1 and 2 aged 7 to 8 years in 2 municipalities in northern Sweden were invited to a questionnaire survey and to skin prick testing to 10 common airborne allergens. The cohort was reexamined in 2010, with additional blood sampling for specific IgE. Participation rates were 90% (n = 1700) at age 7 to 8 years and 85% (n = 1657) at age 11 to 12 years. The results were compared with a cohort examined by identical methods 10 years earlier.

RESULTS

The prevalence of positive skin prick test result to any allergen increased from 30% at age 7 to 8 years to 41% at age 11 to 12 years (P < .001). The cumulative 4-year incidence was 18%, while remission was low. Sensitization to pollen and furred animals was most common. A family history of allergy was significantly associated with incident sensitization, whereas the presence of furred animals at home was negatively associated. The prevalence at age 7 to 8 years and at age 11 to 12 years and the 4-year incidence were all significantly higher compared with the cohort examined 10 years earlier.

CONCLUSIONS

The prevalence of allergic sensitization increased by age as a consequence of a high incidence and a low remission. The trends of increasing incidence and prevalence among schoolchildren imply future increases in the prevalence of allergic diseases.

Early House Dust Mite Sensitivity in Mumbai Children

OBJECTIVE

To identify house dust mite (HDM) sensitivity by skin prick test in children with allergic rhinitis, allergic wheezing and eczema.

METHODS

In this prospective study, children with persistent or recurrent allergic symptoms of rhinitis, wheezing and eczema were enrolled to undergo skin prick testing. Sensitivity was checked for three mites: Dermatophagoide farinae, Dermatophagoide pteronyssinus, and Blomia tropicalis.

RESULTS

Total 92 children underwent skin prick test; 49 (53.2 %) showed significant positivity to one or more dust mite. In the HDM sensitized group, a positive family history of allergic disorders was present in 32 children (65.3 %). In the HDM sensitized group, 18 (36.7 %) children had allergic rhinitis. The youngest child in this group was 12-mo-old. Ten (55.55 %) children were less than 24 mo of age. Significant sensitization to mites was detected in 7 (14.28 %) children with eczema. All children were below 24 mo of age. In children with a tendency to wheeze frequently without any evidence of infections or other systemic disease, 24 (48.9 %) had sensitization to HDM. The youngest child was 15 mo of age. Ten (41.6 %) children were below 24 mo of age. Sensitivity to Blomia tropicalis was detected in 6 (12.24 %) children. Significantly more number of children were sensitive to D. pteronyssinus as compared to D. farinae (65.31 % vs. 46.94 %; p = 0.034).

CONCLUSIONS

Children in Mumbai show early sensitization to HDM. D. pteronyssinus is the commonest offending allergen in the index study.

IgE antibodies in relation to prevalence and multimorbidity of eczema, asthma, and rhinitis from birth to adolescence

BACKGROUND

Eczema, asthma, and rhinitis affect a large proportion of children, but their prevalence varies with age. IgE antibodies are also common in the pediatric population. However, the links between IgE, disease, and trajectories are unclear.

OBJECTIVE

To better understand the links between sensitization and disease, we studied IgE sensitization ever in relation to eczema, asthma, and rhinitis, in children followed up to 16 years of age.

METHODS

From the Swedish population-based birth cohort BAMSE, 2607 children were included. Parental reports from six time points between 1 and 16 years were used to identify children with eczema, asthma, and rhinitis. Blood was collected at 4, 8, and 16 years, and sensitization ever was defined as allergen-specific IgE ≥0.35 kUA /l to common food and/or inhalant allergens at any time point. Odds ratios for eczema, asthma, rhinitis, and multimorbidity in relation to sensitization ever were calculated using generalized estimating equations.

RESULTS

Fifty-one percent were sensitized at least once up to 16 years. Almost a quarter of ever-sensitized children did not have any disease. After adjustment for potential confounders, sensitization ever was significantly associated with the following: (i) eczema throughout childhood, (ii) multimorbidity of eczema, asthma, and rhinitis from 1 to 16 years (OR for multimorbidity: 5.11, 95% CI: 3.99-6.55), (iii) asthma and rhinitis from 4 to 16 years of age.

CONCLUSIONS

Specific IgE is strongly associated with eczema and allergic multimorbidity throughout childhood and with asthma and rhinitis from age 4 years. However, 23% of the children with IgE sensitization do not develop any disease in childhood.

Sensitization to milk, egg and peanut from birth to 18 years: A longitudinal study of a cohort at risk of allergic disease

BACKGROUND

Longitudinal data on the natural history of food sensitization beyond early childhood are scarce. We aimed to investigate the natural history of milk, egg and peanut sensitization from infancy to 18 years and assess whether early food sensitization predicted adolescent food allergy.

METHODS

Sensitization to cow's milk, hen's egg and peanut was measured by skin prick testing at ages 6 months, 1, 2, 12 and 18 years in a high-risk allergy birth cohort (n = 620). Generalized additive models investigated interactions with sex, eczema and aeroallergen sensitization in infancy. Logistic regression assessed the relationships between early food sensitization and adolescent sensitization and probable food allergy up to 18 years.

RESULTS

The prevalence of egg and peanut sensitization peaked at 12 months, while milk sensitization peaked at both 1 and 12 years. Boys with early eczema had the highest prevalences of milk and egg sensitization throughout follow-ups. However, neither sex nor eczema influenced the prevalence of peanut sensitization over time. New onset food sensitization beyond the age of 2 was observed in 7% of participants. Food sensitization at 12 months was associated with increased risk of adolescent food sensitization and adolescent probable food allergy, with sensitization to more than one food allergen had the strongest predictor.

CONCLUSIONS

Food sensitization prevalence is highest in infancy and declines after 12 months of age. Boys with early-life eczema have the highest prevalence of milk and egg sensitization. Food sensitization at 12 months can predict children at greater risk of adolescent sensitization and probable food allergy at 12 and 18 years.

TSLP polymorphisms, allergen exposures, and the risk of atopic disorders in children

BACKGROUND

Thymic stromal lymphopoietin (TSLP) polymorphisms influence atopy risk. TSLP might constitute a key interface between the environment and the allergic immune response. However, whether the effects of TSLP polymorphisms on atopic dermatitis (AD) are modified by allergic sensitization is not clear.

OBJECTIVE

To evaluate the joint effect of allergic sensitization and TSLP polymorphisms on AD and to test whether TSLP polymorphisms increase the risk of asthma in children with AD.

METHODS

A total of 1,520 kindergarten children (375 with AD and 1,145 controls) selected from the Childhood Environment and Allergic Diseases Study cohort in 2010 were enrolled. Information about allergic diseases and environmental exposures was collected by questionnaire. Skin prick tests were performed to measure allergic sensitization. TSLP polymorphisms were genotyped by TaqMan assay. Logistic regressions were conducted to estimate the association among TSLP polymorphisms, allergic sensitization, and AD. For replication, a subsample of the British Isle of Wight birth cohort was used.

RESULTS

The TSLP rs2289278 CC genotype increased the risk of AD (odds ratio 1.90, 95% confidence interval 1.12-3.22). In children sensitized to certain allergens, a genetic predisposition (rs2289278 genotype CC) significantly increased the risk of AD. These findings were replicated in the British subsample using rs2289276 genotypes TT and TC, which are in linkage disequilibrium with rs2289278. In subjects with AD, the rs2289278 C allele also significantly increased the risk of developing asthma (odds ratio 8.31, 95% confidence interval 1.08-64.13).

CONCLUSION

The association of rs2289278 with AD was stronger in children with allergic sensitization than in children without atopy. TSLP polymorphisms also increased the risk of asthma in children with AD.

A population-based study of animal component sensitization, asthma, and rhinitis in schoolchildren

BACKGROUND

Animal sensitization is a major determinant of asthma in children. Component-resolved studies of unselected pediatric populations are lacking. The aim was to describe sensitization to animal components and the association with asthma and rhinitis in animal-sensitized schoolchildren.

METHODS

A random sample of 696 children (11-12 years) from a Swedish population-based cohort was tested for sensitization to cat, dog, and horse dander using ImmunoCAP. Sera from animal-sensitized children were further analyzed by microarray including three allergen components from cat, four from dog, and two from horse. The parents completed an expanded ISAAC questionnaire.

RESULTS

Of 259 animal-sensitized children (≥0.1 kUA /l), 51% were sensitized to all three, 23% to two, and 25% to one species. Current asthma and asthma symptoms following contact with cats were associated with co-sensitization to Fel d 1 and Fel d 4. This association was seen already at moderate-level sensitization (1-15 ISU) to Fel d 4, at which level most children were sensitized to Fel d 1, as well. In dog-sensitized children, the majority was sensitized to more than one dog component, and co-sensitization to Can f 5 and Can f 1/f 2 conferred the greatest risk for asthma. Sensitization to the highly cross-reactive serum albumins was uncommon and not associated with asthma.

CONCLUSIONS

Among schoolchildren in northern Sweden, where mite allergy is uncommon, furry animals were the primary perennial sensitizers. Asthma was associated with higher levels of component sensitization, and sensitization to more than one component from the same animal conferred the greatest risk.

DNA methylation loci associated with atopy and high serum IgE: a genome-wide application of recursive Random Forest feature selection

BACKGROUND

The prevalence of allergic diseases are increasing worldwide, emphasizing the need to elucidate their pathogeneses. The aims of this study were to use a two-stage design to identify DNA methylation levels at cytosine-phosphate-guanine (CpG) sites across the genome associated with atopy and high serum immunoglobulin E (IgE), then to replicate our findings in an independent cohort.

METHODS

Atopy was assessed via skin prick tests and high serum IgE. Methylation levels were measured from whole blood using the Illumina Infinium HumanMethylation450 BeadChip from 18-year-old women (n = 245) and men (n = 122) in the Isle of Wight birth cohort. After data cleaning and processing, and removing probes with possible single nucleotide polymorphisms, DNA methylation levels from 254,460 CpG sites from the 245 women were subjected to recursive Random Forest feature selection for stage 1. The sites selected from stage 1 were tested in stage 2 for associations with atopy and high IgE levels (>200 kU/L) via logistic regression adjusted for predicted cell-type proportions and sex. Sites significantly associated with atopy in stage 2 underwent replication tests in the independent Swedish birth cohort BAMSE (n = 464).

RESULTS

In stage 1, 62 sites were selected, of which 22 were associated with atopy in stage 2 (P-value range 6.5E-9 to 1.4E-5) and 12 associated with high IgE levels (P-value range 1.1E-5 to 7.1E-4) at the Bonferroni adjusted alpha (0.05/62 = 0.0008). Of the 19 available sites, 13 were replicated.

CONCLUSIONS

We identified 13 novel epigenetic loci associated with atopy and high IgE that could serve as candidate loci for future studies; four were within genes with known roles in the immune response (cg04983687 in the body of ZFPM1, cg18219873 in the 5'UTR of PRG2, cg27469152 in the 3'UTR of EPX, and cg09332506 in the body of COPA).

Allergic sensitization and filaggrin variants predispose to the comorbidity of eczema, asthma, and rhinitis: results from the Isle of Wight birth cohort

BACKGROUND

Allergic sensitization and filaggrin gene (FLG) variants are important risk factors for allergic disorders; however, knowledge on their individual and interactive effects on the coexistence of eczema, asthma, and rhinitis is lacking.

OBJECTIVE

This study aimed at investigating the single and combined effects of allergic sensitization and FLG variants on the development of single and multiple allergic disorders.

METHODS

The Isle of Wight birth cohort (n = 1456) has been examined at 1, 2, 4, 10, and 18 years of age. Repeated measurements of eczema, asthma, rhinitis, and skin prick tests were available for all follow-ups. FLG variants were genotyped in 1150 participants. Associations of allergic sensitization and FLG variants with single and multiple allergic disorders were tested in log-binomial regression analysis.

RESULTS

The prevalence of eczema-, asthma-, and rhinitis-only ranged from 5.6% to 8.5%, 4.9% to 10.2%, and 2.5% to 20.4%, respectively, during the first 18 years of life. The coexistence of allergic disorders is common, with approximately 2% of the population reporting the comorbidity of 'eczema, asthma, and rhinitis' during the study period. In repeated measurement analyses, allergic sensitization and FLG variants, when analysed separately, were associated with having single and multiple allergic disorders. Of particular significance, their combined effect increased the risk of 'eczema and asthma' (RR = 13.67, 95% CI: 7.35-25.42), 'asthma and rhinitis' (RR = 7.46, 95% CI: 5.07-10.98), and 'eczema, asthma, and rhinitis' (RR = 23.44, 95% CI: 12.27-44.78).

CONCLUSIONS AND CLINICAL RELEVANCE

The coexistence of allergic disorders is frequent, and allergic sensitization and FLG variants jointly increased risk of allergic comorbidities, which may represent more severe and complex clinical phenotypes. The interactive effect and the elevated proportion of allergic comorbidities associated with allergic sensitization and FLG variants emphasize their joint importance in the pathogenesis of allergic disorders.

The use of the MeDALL-chip to assess IgE sensitization: a new diagnostic tool for allergic disease?

BACKGROUND

Allergic sensitization is frequently present in asthma and rhinitis, but the role of specific immunoglobulin E (s-IgE) is not always clear. Multiple s-IgE analyses may provide insight into this relationship, thus a microarray chip was developed within the EU-funded MeDALL project. The main objective was to evaluate the performance of the MeDALL-chip compared to ImmunoCAP and skin prick test (SPT) in detecting allergic sensitization in children and secondarily to investigate the association to asthma and allergic rhinitis.

METHODS

From the 'Environment and Childhood Asthma Study', 265 children were investigated at 10 and 16 yr of age with clinical examination, interview, SPT, ImmunoCAP, and the MeDALL-chip including 152 allergen components in the analysis.

RESULTS

Allergic sensitization at 10 yr was more frequently detected using the MeDALL-chip (38.1%) compared to the ImmunoCAP (32.8%) (p = 0.034) and SPT (25.5%) (p < 0.001), but no significant difference was seen at 16 yr (MeDALL-chip 49.8%, ImmunoCAP 48.6%, SPT 45.8%). The MeDALL-chip did not differ significantly from the ImmunoCAP or SPT in terms of detecting allergic sensitization in subjects with rhinitis or asthma at 10 or 16 yr.

CONCLUSION

The prevalence of allergic sensitization increased by all three diagnostic tests from 10 to 16 yr was similar by SPT and ImmunoCAP and significantly higher with the MeDALL-chip at 10 yr. All three tests were comparable for identification of allergic sensitization among children with current rhinitis or asthma.

Early origins of chronic obstructive lung diseases across the life course

Chronic obstructive lung diseases, like asthma and chronic obstructive pulmonary disease, have high prevalences and are a major public health concern. Chronic obstructive lung diseases have at least part of their origins in early life. Exposure to an adverse environment during critical periods in early life might lead to permanent developmental adaptations which results in impaired lung growth with smaller airways and lower lung volume, altered immunological responses and related inflammation, and subsequently to increased risks of chronic obstructive lung diseases throughout the life course. Various pathways leading from early life factors to respiratory health outcomes in later life have been studied, including fetal and early infant growth patterns, preterm birth, maternal obesity, diet and smoking, children's diet, allergen exposure and respiratory tract infections, and genetic susceptibility. Data on potential adverse factors in the embryonic and preconception period and respiratory health outcomes are scarce. Also, the underlying mechanisms how specific adverse exposures in the fetal and early postnatal period lead to chronic obstructive lung diseases in later life are not yet fully understood. Current studies suggest that interactions between early environmental exposures and genetic factors such as changes in DNA-methylation and RNA expression patterns may explain the early development of chronic obstructive lung diseases. New well-designed epidemiological studies are needed to identify specific critical periods and to elucidate the mechanisms underlying the development of chronic obstructive lung disease throughout the life course.

Allergy to furry animals: New insights, diagnostic approaches, and challenges

The prevalence of allergy to furry animals has been increasing, and allergy to cats, dogs, or both is considered a major risk factor for the development of asthma and rhinitis. An important step forward in the diagnosis of allergy to furry animals has been made with the introduction of molecular-based allergy diagnostics. A workshop on furry animals was convened to provide an up-to-date assessment of our understanding of (1) the exposure and immune response to the major mammalian allergens, (2) the relationship of these responses (particularly those to specific proteins or components) to symptoms, and (3) the relevance of these specific antibody responses to current or future investigation of patients presenting with allergic diseases. In this review research results discussed at the workshop are presented, including the effect of concomitant exposures from other allergens or microorganisms, the significance of the community prevalence of furry animals, molecular-based allergy diagnostics, and a detailed discussion of cat and dog components.

Filaggrin loss-of-function mutations are associated with food allergy in childhood and adolescence

BACKGROUND

Filaggrin is an epidermal protein that has a role in skin barrier function. Filaggrin loss-of-function (FLG-LOF) mutations are a significant risk factor for eczema and atopy, but their association with food allergy (FA) is less clear.

OBJECTIVE

We explored the longitudinal relationship between 3 common FLG-LOF mutations and FA using the Isle of Wight birth cohort.

METHODS

FA diagnosis was based on recognized allergic reactions within 4 hours after exposure to known food allergens. Food allergen sensitization (FAS) was identified by using skin prick tests conducted between 1 and 18 years of age to a range of food allergens. Three FLG mutations were genotyped in 1150 (79%) of 1456 children. The temporal relationships between FA, FAS, and eczema in children with FLG mutations were explored by using path analysis with total, direct, and indirect effect models.

RESULTS

There was a significant total effect of FLG-LOF mutations on the risk of FA in later childhood at the ages of 10 (odds ratio, 31.46; 95% CI, 2.86 to >100) and 18 (odds ratio, 4.25; 95% CI, 1.55-11.61) years. Path analysis showed that there was no direct effect of FLG-LOF mutations on FA at any age; however, an indirect effect was found on FA at all ages through eczema and FAS in the earlier years.

CONCLUSION

FLG-LOF mutations are associated with FA in older children through eczema and FAS during early childhood. Our results highlight a biologically plausible pathway, which suggests that skin barrier function is important in the development and persistence of FA.

Atopic phenotypes identified with latent class analyses at age 2 years

BACKGROUND

Atopic sensitization (ie, atopy) is the most commonly reported risk factor for asthma. Recent studies have begun to suggest that atopy, as conventionally defined, might be an umbrella term that obfuscates more specific allergic disease types.

OBJECTIVE

We sought to determine whether distinct and meaningful atopic phenotypes exist within a racially diverse birth cohort using 10 allergen-specific serum IgE (sIgE) measurements from children aged 2 years.

METHODS

Using the Wayne County Health, Environment, Allergy and Asthma Longitudinal Study (WHEALS) birth cohort (62% black), we analyzed sIgE data on 10 allergens (Dermatophagoides farinae, dog, cat, timothy grass, ragweed, Alternaria alternata, egg, peanut, milk, and German cockroach) obtained from 594 children at age 2 years. Conventional atopy was defined as at least 1 sIgE level of 0.35 IU/mL or greater.

RESULTS

A 4-class solution (latent class model) was the best fit. Class types were labeled "low to no sensitization" (76.9% of sample), "highly sensitized" (2.7%), "milk and egg dominated" (15.3%), and "peanut and inhalant(s)" (5.1%). Almost one third (32.2%) of the low to no sensitization group met the criteria for conventional atopy. The highly sensitized group was significantly associated with a doctor's diagnosis of asthma after age 4 years (odds ratio [OR], 5.3; 95% CI, 1.6-17.4), whereas the milk and egg dominated and peanut and inhalant(s) groups were not (ORs of 1.6 [95% CI, 0.8-3.0] and 1.8 [95% CI, 0.6-4.9], respectively). Children of black race were more likely to be in the 3 multisensitized groups (P = .04).

CONCLUSION

Classification by sIgE patterns defined groups whose membership is more strongly associated with atopic dermatitis, wheeze, and asthma compared with conventional atopy.

Developments in the field of allergy in 2012 through the eyes of Clinical & Experimental Allergy

In 2012, we received 683 submissions and published 20 editorials, 38 reviews, 11 letters and 128 original articles. This represents an acceptance rate for original papers in the range of 20%. About 30% of original papers were triaged not to go out to review, either because the editors did not feel they had sufficient priority for publication or because the topic did not feel right for the readers of the journal. We place great emphasis on obtaining sufficient high-quality reviews to make our decisions on publication fair and consistent. Inevitably, however, there is a degree of luck about what gets published and which papers miss out, and we are always happy to receive an appeal on our decisions either at the triage stage or after review. This gives us the opportunity to revisit the decision and revise it or explain in more detail to the authors the basis for the decision. Once again in 2012, we were delighted by the quality of the papers submitted and the breadth and depth of research into allergic disease that it revealed. The pattern of papers submitted was similar in previous years with considerable emphasis on all aspects of asthma and rhinitis. We were particularly pleased with our special issue on severe asthma. Elucidating mechanisms using either animal models or patients has always been a major theme of the journal, and the excellent work in these areas has been summarized by Harissios Vliagoftis with a particularly interesting section on early-life events guiding the development of allergic disease, which understandably continue to be a major theme of research. Magnus Wickman summarized the papers looking at the epidemiology of allergic disease including work from birth cohorts, which are an increasingly rich source of data on risk factors for allergic disease, and two papers on the epidemiology of anaphylaxis. Giovanni Passalacqua discussed the papers in the clinical allergy section of the journal, and Adriano Mari who runs the excellent Allergome website discussed the papers looking at allergens including characterization and the relative usefulness of allergen arrays versus single extracts in diagnosis and management.

The natural course of sensitization and allergic diseases from childhood to adulthood

BACKGROUND

Longitudinal prospective population-based birth cohort studies of the natural history of sensitization and allergic diseases from childhood to adulthood are few. The aim of the present prospective study was to investigate the natural course of sensitization and allergic diseases in a random population-based sample of 276 children from a 1-year birth cohort of unselected Danish children followed from birth to 26 years of age.

METHODS

Questionnaire-based interviews, physical examination, skin prick tests, specific IgE testing, and from 10 years also spirometry, were carried out at 1.5, 5, 10, 15 and 26 years of age. Predefined diagnostic criteria were used.

RESULTS

Follow-up rates were high, 193 (70%) attended the 26-year follow-up. The prevalence of current eczema was stable during childhood; 13% (1.5 yrs.), 9.2% (5 yrs.), 10.8% (10 yrs.), and 9.8% (15 yrs.), and 5.7% at 26 yrs. From birth to 26 years the cumulative prevalence of eczema, food allergy, asthma, and rhinoconjunctivitis was 23.5%, 13.8%, 17%, and 27.9% respectively. More than half of the participants had one or more allergic disease in the period between birth and 26 years of age. The rates of sensitization (S-IgE = 0.35 kU/l) were 8%, 23%, 26%, 32%, and 31% at 1.5, 5, 10, 15, and 26 years of age, respectively. Sensitization to food allergens was most prevalent in early infancy, whereas sensitization to inhalant allergens dominated later on.

CONCLUSION

The results support the concept of the allergic march. Allergic diseases are not only occurring in childhood but persist into adulthood.

Epidemiologic methods of assessing asthma and wheezing episodes in longitudinal studies: measures of change and stability

Background

In settings in which diseases wax and wane, there is a need to measure disease dynamics in longitudinal studies. Traditional measures of disease occurrence (eg, cumulative incidence) do not address change or stability or are limited to stable cohorts (eg, incidence) and may thus lead to erroneous conclusions. To illustrate how different measures can be used to detect disease dynamics, we investigated sex differences in the occurrence of asthma and wheezing, using a population-based study cohort that covered the first 18 years of life.

Methods

In the Isle of Wight birth cohort (n = 1456), prevalence, incidence, cumulative incidence, positive and negative transitions, and remission were determined at ages 1 or 2, 4, 10, and 18 years. Latent transition analysis was used to simultaneously identify classes of asthma and wheezing (related phenotypes) and characterize transition probabilities over time. Trajectory analysis was used to characterize the natural history of asthma and wheezing.

Results

Regarding time-specific changes, positive and negative transition probabilities were more informative than other measures of associations because they revealed a sex switchover in asthma prevalence (P < 0.05). Transition probabilities were able to identify the origin of a sex-specific dynamic; in particular, prior wheezing transitioned to asthma at age 18 years among girls but not among boys. In comparison with latent transition analysis, trajectory analysis did not directly identify a switchover in prevalence among boys and girls.

Conclusions

In longitudinal analyses, transition analyses that impose minimal restrictions on data are needed in order to produce appropriate information on disease dynamics.

Aeroallergen sensitization in childhood asthmatics in northern India

OBJECTIVE

To determine the prevalence of sensitization to common aeroallergens in asthmatic children and study the differences in characteristics of atopics and non atopics.

DESIGN

Analysis of data from a prospective cohort study.

SETTING

Pediatric Chest Clinic of tertiary care center in Northern India.

PATIENTS

Asthmatic children from 5-18 year of age.

MAIN OUTCOME MEASURES

Prevalence of sensitization to common aeroallergens.

RESULTS

Skin prick testing (SPT) was performed on 180 children above 5 years of age, with a mean (SD) age of 111.4 (34.2) months. 100 children (55.6%) were sensitized to at least one aeroallergen, suggesting atopy; 68 (37.8%) were sensitized to more than one allergen. 36.7% children were sensitized to housefly antigen; 31.1% to rice grain dust, 18.3% to cockroach, and 7.8% to house dust mite antigens. Atopic children had significantly higher median FENO during follow up than non-atopic children (17.5 ppb vs 13 ppb, P=0.002). There was a positive correlation between age and the number of allergens that an individual was sensitized to (r= 0.21; P=0.0049).

CONCLUSIONS

More than half of asthmatic children in our cohort had sensitization to one or more aeroallergens suggesting atopy; sensitization was most commonly seen to housefly antigen and rice grain dust. Atopic children had significantly higher FENO measurements during follow up as compared to non-atopic children.

Maternal plasma phosphatidylcholine fatty acids and atopy and wheeze in the offspring at age of 6 years

Variation in exposure to polyunsaturated fatty acids (PUFAs) might influence the development of atopy, asthma, and wheeze. This study aimed to determine whether differences in PUFA concentrations in maternal plasma phosphatidylcholine are associated with the risk of childhood wheeze or atopy. For 865 term-born children, we measured phosphatidylcholine fatty acid composition in maternal plasma collected at 34 weeks' gestation. Wheezing was classified using questionnaires at 6, 12, 24, and 36 months and 6 years. At age of 6 years, the children underwent skin prick testing, fractional exhaled nitric oxide (FENO) measurement, and spirometry. Maternal n-6 fatty acids and the ratio of n-3 to n-6 fatty acids were not associated with childhood wheeze. However, higher maternal eicosapentaenoic acid, docosahexaenoic acid, and total n-3 fatty acids were associated with reduced risk of non-atopic persistent/late wheeze (RR 0.57, 0.67 and 0.69, resp. P = 0.01, 0.015, and 0.021, resp.). Maternal arachidonic acid was positively associated with FENO (P = 0.024). A higher ratio of linoleic acid to its unsaturated metabolic products was associated with reduced risk of skin sensitisation (RR 0.82, P = 0.013). These associations provide some support for the hypothesis that variation in exposure to n-6 and n-3 fatty acids during pregnancy influences the risk of childhood wheeze and atopy.