Prediction and prevention of atopic allergy

Human Milk and Allergic Diseases: An Unsolved Puzzle

There is conflicting evidence on the protective role of breastfeeding in relation to the development of allergic sensitisation and allergic disease. Studies vary in methodology and definition of outcomes, which lead to considerable heterogeneity. Human milk composition varies both within and between individuals, which may partially explain conflicting data. It is known that human milk composition is very complex and contains variable levels of immune active molecules, oligosaccharides, metabolites, vitamins and other nutrients and microbial content. Existing evidence suggests that modulation of human breast milk composition has potential for preventing allergic diseases in early life. In this review, we discuss associations between breastfeeding/human milk composition and allergy development.

Atopic dermatitis in a high-risk cohort: natural history, associated allergic outcomes, and risk factors

BACKGROUND

Atopic dermatitis (AD) is commonly associated with asthma and other atopic disorders in childhood.

OBJECTIVE

To evaluate the natural history of AD and its association with other allergic outcomes in a high-risk cohort through the age of 7 years.

METHODS

A total of 373 high-risk infants, who had undergone a randomized controlled trial with intervention measures for primary prevention of asthma applied during the first year of life, were assessed for asthma, AD, and allergic sensitization at 1, 2, and 7 years.

RESULTS

The multifaceted intervention program did not reduce AD despite reducing the prevalence of asthma significantly. Sixty-two children (16.6%) had AD during the first 2 years (early-onset AD); of these, 26 continue to have AD at the age of 7 years (persistent), whereas 36 no longer had the disease (nonpersistent) at the age of 7 years. Twenty-three children (6.2%) developed AD only after the age of 2 years (late-onset AD). Early-onset AD, persistent or nonpersistent, was associated with increased risk of allergic sensitization to food allergens within the first 2 years of life and asthma diagnosis at year 7. However, only persistent AD was associated with an increased risk of other atopic diseases and allergic sensitization to food and aeroallergens at year 7. Late-onset AD was not associated with atopic diseases or allergic sensitization at year 7 with the exception of Alternaria alternans.

CONCLUSION

In this cohort of infants at high risk of asthma, early-onset persistent AD, which was highly associated with atopic sensitization, increased the risk of atopic diseases in later childhood and thus appears to be part of the atopic march.

Knowledge and practice of physicians and nutritionists regarding the prevention of food allergy

BACKGROUND & AIMS

To evaluate the knowledge and practice of pediatricians, pediatric gastroenterologists, allergists and nutritionists regarding the primary prevention of food allergy.

METHODS

A descriptive, cross-sectional study that enrolled pediatricians (n = 80), pediatric gastroenterologists (n = 120), allergists (n = 100) and nutritionists (n = 220). A self-administered questionnaire concerning the current recommendations was used.

RESULTS

Despite the lack of current recommendations, 17.1% (n = 89) of all professionals, mainly nutritionists, recommended a maternal exclusion diet during pregnancy. More professionals in the sample group, 40.8% (n = 212), recommended a maternal exclusion diet during breastfeeding, and the rates of recommendation were higher in nutritionists and pediatricians compared to allergists and pediatric gastroenterologists (p < 0.001). Regarding the recommended timing of the introduction of complementary feeding, 41.9% (n = 218) of the professionals recommended modifying the age of introduction to prevent the development of food allergy. The majority of the professionals believed that prebiotics (61.2%; n = 318) and probiotics (44.4%; 231) prevent the development of food allergy. The recommended age of introduction for the main allergenic foods was 12 months.

CONCLUSIONS

This study revealed that there are gaps in the knowledge of professionals about the primary prevention of food allergy.

Exposure to gene-environment interactions before 1 year of age may favor the development of atopic dermatitis

BACKGROUND

The aims of this study were to determine (1) the prevalence of atopic dermatitis (AD) in Seoul, Korea, and (2) the influence of environmental and genetic factors on disease risk.

METHODS

A questionnaire survey was conducted in 5,036 primary school children and 4,607 middle school children in 2008. For each child, a modified version of the International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire and a questionnaire assessing exposure to environmental variables were completed.

RESULTS

In primary school children, the lifetime prevalence of itchy eczema was 24.3%, the 12-month prevalence of itchy flexural eczema was 18.0%, the lifetime prevalence of AD diagnosis was 31.3%, and the 12-month prevalence of AD treatment was 14.5%. In middle school children, the corresponding rates were 16.0, 10.8, 22.1, and 8.3%, respectively. These rates are significantly higher than those reported in similar studies conducted in 1995 and 2000. In both primary and middle school children, a parental history of allergic disease and a history of having moved into a newly built house before 1 year of age were independently associated with a risk for current AD. For current AD, the prevalence odds ratio was higher in the subgroup with both a genetic and a specific environmental risk factor than in the subgroup with no risk factor or subgroups with only one risk factor.

CONCLUSIONS

The prevalence of AD in primary and middle school children in Seoul has increased. Its development may be influenced by gene-environment interactions, particularly before 1 year of age.

Cord blood house dust mite allergen in newborns: relationship to maternal blood levels of allergen and allergen specific IgG and IgE

BACKGROUND

House dust mite allergen has previously been detected in the cord blood of some newborns but not others. The factors that affect the presence and levels in cord blood of this and possibly other allergens are unknown.

OBJECTIVE

To test the hypothesis that the levels of maternal allergen and allergen specific IgG affect the presence and levels of newborn allergen.

METHODS

Enzyme-linked immunosorbent assays were used to measure the levels of house dust mite allergen Der p 1 and Der p 1 specific IgG and IgE in paired blood samples from 98 mothers and full-term newborns.

RESULTS

Der p 1 was detected in 27 mothers and 12 newborns. None of the 71 mothers who lacked Der p 1 had Der p 1-positive newborns. When present, cord blood Der p 1 levels correlated with and were approximately one third of Der p 1 levels in maternal blood. Cord blood Der p 1 levels also tended to correlate with maternal blood levels of Der p 1 specific IgG but showed little, if any, correlation with maternal blood levels of Der p 1 specific IgE.

CONCLUSIONS

When detectable, the levels of an allergen in the blood of newborns correlate with the levels of that allergen in the blood of their mothers and tend to be related to maternal levels of allergen specific IgG.

The Australasian Society of Clinical Immunology and Allergy position statement: Summary of allergy prevention in children

A family history of allergy and asthma identifies children at high risk of allergic disease. Dietary restrictions in pregnancy are not recommended. Avoiding inhalant allergens during pregnancy has not been shown to reduce allergic disease, and is not recommended. Breastfeeding should be recommended because of other beneficial effects, but if breast feeding is not possible, a hydrolysed formula is recommended (rather than conventional cow's milk formulas) in high-risk infants only. Maternal dietary restrictions during breastfeeding are not recommended. Soy formulas and other formulas (eg, goat's milk) are not recommended for reducing food allergy risk. Complementary foods (including normal cow's milk formulas) should be delayed until a child is aged at least 4-6 months, but a preventive effect from this measure has only been demonstrated in high-risk infants. There is no evidence that an elimination diet after age 4-6 months has a protective effect, although this needs additional investigation. Further research is needed to determine the relationship between house dust mite exposure at an early age and the development of sensitisation and disease; no recommendation can yet be made about avoidance measures for preventing allergic disease. No recommendations can be made about exposure to pets in early life and the development of allergic disease. If a family already has pets it is not necessary to remove them, unless the child develops evidence of pet allergy (as assessed by an allergy specialist). Women should be advised not to smoke while pregnant, and parents should be advised not to smoke. No recommendations can be made on the use of probiotic supplements (or other microbial agents) for preventing allergic disease at this time. Immunotherapy may be considered as a treatment option for children with allergic rhinitis, and may prevent the subsequent development of asthma.

Does having children affect adult smoking prevalence and behaviours at home?

BACKGROUND

Smoking prevalence and smoking behaviours have changed in society and an increased awareness of the importance of protecting children from environmental tobacco smoke (ETS) is reported. The aim of this study was to find out if smoking prevalence and smoking behaviours were influenced by parenthood, and if differences in health-related quality of life differed between smoking and non-smoking parents.

METHODS

Questionnaires were sent to a randomly selected sample, including 1735 men and women (20-44 years old), residing in the south-east of Sweden. Participation rate was 78%. Analyses were done to show differences between groups, and variables of importance for being a smoker and an indoor smoker.

RESULTS

Parenthood did not seem to be associated with lower smoking prevalence. Logistic regression models showed that smoking prevalence was significantly associated with education, gender and mental health. Smoking behaviour, as well as attitudes to passive smoking, seemed to be influenced by parenthood. Parents of dependent children (0-19 years old) smoked outdoors significantly more than adults without children (p < 0.01). Logistic regression showed that factors negatively associated with outdoor smoking included having immigrant status, and not having preschool children. Parents of preschool children found it significantly more important to keep the indoor environment smoke free than both parents with schoolchildren (p = 0.02) and adults without children (p < 0.001). Significant differences in self-perceived health-related quality of life indexes (SF-36) were seen between smokers and non-smokers.

CONCLUSION

As smoking behaviour, but not smoking prevalence, seems to be influenced by parenthood, it is important to consider the effectiveness of commonly used precautions when children's risk for ETS exposure is estimated.

Does Having Children Affect Adult Smoking Prevalence and Behaviours at Home?

Background

Smoking prevalence and smoking behaviours have changed in society and an increased awareness of the importance of protecting children from environmental tobacco smoke (ETS) is reported. The aim of this study was to find out if smoking prevalence and smoking behaviours were influenced by parenthood, and if differences in health-related quality of life differed between smoking and non-smoking parents.

Methods

Questionnaires were sent to a randomly selected sample, including 1735 men and women (20–44 years old), residing in the south-east of Sweden. Participation rate was 78%. Analyses were done to show differences between groups, and variables of importance for being a smoker and an indoor smoker.

Results

Parenthood did not seem to be associated with lower smoking prevalence. Logistic regression models showed that smoking prevalence was significantly associated with education, gender and mental health. Smoking behaviour, as well as attitudes to passive smoking, seemed to be influenced by parenthood. Parents of dependent children (0–19 years old) smoked outdoors significantly more than adults without children (p < 0.01). Logistic regression showed that factors negatively associated with outdoor smoking included having immigrant status, and not having preschool children. Parents of preschool children found it significantly more important to keep the indoor environment smoke free than both parents with schoolchildren (p = 0.02) and adults without children (p < 0.001). Significant differences in self-perceived health-related quality of life indexes (SF-36) were seen between smokers and non-smokers.

Conclusion

As smoking behaviour, but not smoking prevalence, seems to be influenced by parenthood, it is important to consider the effectiveness of commonly used precautions when children's risk for ETS exposure is estimated.

Primary prevention of asthma and atopy during childhood by allergen avoidance in infancy: a randomised controlled study

BACKGROUND

Recent increases in the prevalence of asthma and atopy emphasise the need for devising effective methods for primary prevention in children at high risk of atopy.

METHOD

A birth cohort of genetically at risk infants was recruited in 1990 to a randomised controlled study. Allergen avoidance measures were instituted from birth in the prophylactic group (n=58). Infants were either breast fed with mother on a low allergen diet or given an extensively hydrolysed formula. Exposure to house dust mite was reduced by the use of an acaricide and mattress covers. The control group (n=62) followed standard advice as normally given by the health visitors. At age 8, all 120 children completed a questionnaire and 110 (92%) had all assessments (skin prick test, spirometry, and bronchial challenges).

RESULTS

In the prophylactic group eight children (13.8%) had current wheeze compared with 17 (27.4%) in the control group (p=0.08). Respective figures were eight (13.8%) and 20 (32.3%) for nocturnal cough (p=0.02) and 11 of 55 (20.0%) and 29 of 62 (46.8%) for atopy (p=0.003). After adjusting for confounding variables, the prophylactic group was found to be at a significantly reduced risk for current wheeze (odds ratio (OR) 0.26 (95% confidence interval (CI) 0.07 to 0.96)), nocturnal cough (OR 0.22 (95% CI 0.06 to 0.83)), asthma as defined by wheeze and bronchial hyperresponsiveness (OR 0.11 (95% CI 0.01 to 1.02)), and atopy (OR 0.21 (95% CI 0.07 to 0.62)).

CONCLUSION

Strict allergen avoidance in infancy in high risk children reduces the development of allergic sensitisation to house dust mite. Our results suggest that this may prevent some cases of childhood asthma.

Hidden peanut allergens detected in various foods: findings and legal measures

BACKGROUND

Undeclared allergens in foodstuffs represent a major health problem for sensitized persons. Until recently, most food control authorities were not in the position to monitor hidden allergens and to take legal measures against their presence in foodstuffs.

METHODS

In this study, we employed human sera-based immunoassay techniques, enabling semiquantitative detection and identification of peanut allergens in a variety of foodstuffs.

RESULTS

This study showed the presence of undeclared allergens in products belonging to various food categories, such as cereals, cookies, cakes, and snacks. The detection limit for peanut contamination was in most instances less than 50 mg peanut material per kg, i.e., less than about 5 mg peanut allergens per kg. We legally objected to products with more than one part per thousand or 1000 mg/kg of peanut contamination.

CONCLUSIONS

In most cases, food producers, confronted with our results, were able to detect and eliminate the sources of the contamination. They implemented measures to prevent the presence of hidden peanut allergens in their products, increasing food safety for sensitized persons and overall food quality.

Food allergen avoidance in primary prevention of food allergy

Approximately 5-10% of children suffer from allergy to one or more foods. Primary prevention through a hypoallergenic diet may reduce the prevalence of food allergy and associated co-morbidity, such as eczema and urticaria. Breastfeeding has many advantages and should be recommended for all children. Those with a history of atopy in the immediate family are at a higher risk and maternal diet during lactation, avoiding highly allergenic foods, may enhance the benefit. Cow's milk should be strictly avoided, and supplements, if required, should be with a hypoallergenic formula. Delayed introduction of egg, nuts, wheat and fish has also been suggested. Dietary restriction may have nutritional consequences for the mother and child and supervision by a dietician is essential. Maternal diet during pregnancy is not advisable as the benefit is minimal and there may be adverse effects on the foetal nutrition. In high risk infants, a combined approach, where breastfeeding with maternal avoidance of highly allergenic foods, supplemented by extensively hydrolysed formula during the first 6 months of life, in addition to the delayed introduction of solid foods, has been shown to reduce the development of food allergy in infants.

Soluble CD30 and CD23 in cord blood are not related to atopy in early childhood

Atopic disease, including atopic dermatitis (AD), is associated with a T-helper 2 (Th2)-dependent immune response. The cytokine receptor CD30 appears to be preferentially expressed on, and its soluble form (sCD30) released by, Th2 cells. Therefore, sCD30 may be a potential marker for atopic disorders. The aim of this study was to test the hypothesis that the sCD30 level in cord blood could be used to predict the development of atopy or AD in early childhood. In a case-control study, levels of sCD30, as well as soluble low-affinity immunoglobulin E (IgE) receptor (sCD23), interleukin-4 (IL-4) and IgE, were measured in cord blood in 35 children who subsequently developed allergic sensitization and AD before the age of three, and the results were compared to those of 35 matched children without a history of atopy. There was no difference in cord blood levels of sCD30 between controls (32.5 U/ml; 19.7-80.1) and children with subsequent atopy and AD (32.2 U/ml; 22-75.9) (median; quartiles). The concentration of sCD30 showed no relation to the levels of total IgE, sCD23 or IL-4. Levels of sCD23 were similar in children with subsequent atopy (60.2 U/ml; 44.5-76.8) and controls (55.2 U/ml; 38.3-72.5), whereas IL-4 was detectable in 10 of the atopic children and in only two of the controls (p <0.05). In conclusion, cord blood levels of sCD30 or sCD23 do not seem to be related to the subsequent development of atopy or AD at the age of three.