Parental atopy and risk of atopic dermatitis in the first two years of life in the BASELINE birth cohort study

BACKGROUND

Atopic dermatitis (AD) has a strong genetic basis. The objective of this study was to assess the association between parental atopy and AD development by 2 years.

METHODS

A secondary data analysis of the BASELINE Birth Cohort study was performed (n = 2183). Parental atopy was self-reported at 2 months. Infants were examined for AD by trained health care professionals at 6, 12, and 24 months. Variables extracted from the database related to skin barrier function, early skincare, parental atopy, and AD. Statistical analysis adjusted for potential confounding variables.

RESULTS

Complete data on AD status were available for 1505 children at 6, 12, and 24 months. Prevalence of AD was 18.6% at 6 months, 15.2% at 12 months, and 16.5% at 24 months. Adjusted odds ratios (95% CIs) following multivariable analysis were 1.57 (1.09-2.25) at 6 months and 1.66 (1.12-2.46) at 12 months for maternal AD; 1.90 (1.28-2.83) at 6 months and 1.85 (1.20-2.85) at 24 months for paternal AD; 1.76 (1.21-2.56) at 6 months and 1.75 (1.16-2.63) at 12 months for maternal asthma; and 1.70 (1.19-2.45) at 6 months, 1.86 (1.26-2.76) at 12 months, and 1.99 (1.34-2.97) at 24 months for paternal asthma. Parental rhinitis was only associated with AD with maternal rhinitis at 24 months (aOR (95% CI): 1.79 (1.15-2.80)).

CONCLUSION

Parental AD and asthma were associated with increased risk of objectively diagnosed AD in offspring in this contemporary cohort.

Impact of maternal, antenatal and birth-associated factors on iron stores at birth: data from a prospective maternal-infant birth cohort

BACKGROUND/OBJECTIVES

Low serum ferritin concentrations at birth, which reflect neonatal iron stores, track through to early childhood and have been associated with poorer neurodevelopmental outcomes. We aimed to identify maternal, antenatal and birth-associated factors that influence iron stores at birth in a prospective maternal-infant birth cohort.

SUBJECTS/METHODS

In a population-based, longitudinal, birth cohort in Ireland, 413 maternal-infant dyads with prospectively collected lifestyle and clinical data from 15 weeks' gestation had umbilical cord serum ferritin concentrations measured. Regression models were developed to identify independent factors associated with cord ferritin concentrations.

RESULTS

Median (IQR) cord ferritin concentrations were 185.7 (131.7, 385.5) μg/l, and 8% (n=33) of infants had low iron stores (ferritin <76 μg/l) at birth. Maternal obesity (BMI ⩾30 kg/m²) at 15 weeks' gestation (adj. estimate (95% confidence interval (CI)): -66.4 (-106.9, -25.9) μg/l, P<0.0001) and delivery by caesarean section (-38.8 (-70.2, -7.4) μg/l, P=0.016) were inversely associated with cord ferritin concentrations. In addition, maternal smoking at 15 weeks' gestation (adj. odds ratio (95% CI): 2.9 (1.2, 7), P=0.020) and being born small-for-gestational age (3.4 (1.3, 8.9), P=0.012) were associated with an increased risk of low iron stores (ferritin <76 μg/l) at birth.

CONCLUSIONS

We have identified a number of potentially modifiable lifestyle factors that influence iron stores at birth, with the important role of overall maternal health and lifestyle during pregnancy highlighted. Public health policies targeting women of child-bearing age to improve nutrition and health outcomes should be prioritised for the health of the next generation.

Is hospital based MMR vaccination for children with egg allergy here to stay?

Egg allergy is incorrectly considered to constitute a contraindication to MMR in the community, despite a long history of its safe administration to egg allergic children. The product insert perpetuates this misinformation but the Irish guidelines from the RCPI are unequivocal. We reviewed all paediatric cases vaccinated in our hospital in 2007-2008. Forty seven of 91 children receiving vaccinations in hospital, had been referred for MMR due to concerns regarding egg allergy. In 32% (n=15), GP referral for vaccination was made despite correspondence from the clinic advising routine vaccination in the community. Nineteen were second MMR immunisations, which should all have occurred in the community. Unnecessary hospital referral for MMR vaccination is an extra burden on hospital resources, and causes unwarranted anxiety amongst parents of children with egg allergy. A change in practice seems difficult to achieve, as many referrals happen despite individualised correspondence to GPs and other referring clinicians outlining the current guidelines.

The effect of digestion and pH on the allergenicity of kiwifruit proteins

It is suggested that patients with oral allergy syndrome (OAS) respond to pepsin-sensitive allergens, and systemic reactors identify pepsin-resistant allergens. We sought to assess the digestibility of kiwifruit proteins in simulated gastric fluid (SGF), and to compare the immunogenicity of the digests in patients with isolated oral and systemic reactions to kiwifruit. In addition, the effect of pH on digestibility of kiwifruit proteins was investigated. The in vitro resistance of kiwifruit proteins to digestion was determined using SGF. G-immunoglobulin (IgE) binding to digested proteins was investigated by Western blotting using sera from children and adults (aged 5-72 yr) with systemic reactions and patients with isolated oral symptoms. To determine whether pH conditions influence digestion of kiwifruit extracts, digestion at pHs 1.5-7 were compared by SDS-PAGE. Patients with systemic reactions showed IgE binding to digestion-resistant allergens, but patients with oral symptoms reacted only to digestion-labile allergens. An increase in pH from 1.5 to 2.5 significantly reduced pepsin breakdown of kiwifruit allergens. Immunoreactive digested protein fragments were detectable by immunoblot but not Coomassie stain. This study confirms a difference in the lability of food allergens recognized by patients with systemic reactions and those with OAS. Pepsin digestion of kiwifruit proteins was impaired by hypoacidic conditions suggesting that patients with hypoacidic gastric conditions are at increased risk of systemic absorption of allergens. The data indicate that commonly used methods for predicting allergenicity of novel proteins using Coomassie stains may be flawed.

Presentation of allergen in different food preparations affects the nature of the allergic reaction - a case series

BACKGROUND

Characterization of fatal and non-fatal reactions to food indicates that the majority of reactions are due to the ingestion of prepared foods rather than the non-processed allergen. In an ongoing study that used a double-blind placebo-controlled food challenge to investigate peanut allergy and clinical symptoms, the observed reaction severity in four of the first six subjects was greater than anticipated. We hypothesized that this was due to differences in the composition of the challenge vehicle.

OBJECTIVE

The aim was to investigate whether the severity of observed challenge reactions would be repeated on re-challenge with a lower fat challenge vehicle.

METHODS

Peanut-allergic subjects were re-challenged with a lower fat recipe after reacting more severely than was anticipated to an initial peanut challenge. Similar challenge vehicle recipes were used, the only difference being the lower fat content (22.9% compared with 31.5%). The peanut content of the two recipes was analysed using RAST inhibition studies and ELISA tests.

RESULTS

Three of four subjects reacted to much smaller doses of peanut protein on re-challenge (mean dose equivalence - 23 times less peanut) with the lower fat recipe. RAST inhibition showed that neither recipe altered epitope recognition. The higher fat recipe required twice as much peanut to cause 50% inhibition. ELISA detected far lower levels of peanut in the higher fat recipe (220 000 parts per million (p.p.m.)) than in the lower fat recipe (990 000 p.p.m.).

CONCLUSION

The fat content of a challenge vehicle has a profound effect on the reaction experienced after allergen ingestion. This is another factor to be considered in assessing the risk of certain foods to food-allergic consumers and adds another dimension to clinical, research and regulatory practice.