Dust Mite Allergens in Breast Milk Linked to Allergic Disease

By Anne Harding

September 08, 2016

NEW YORK (Reuters Health) - Exposure to respiratory house dust mite (HDM) allergen in breast milk is associated with increased risk of allergic sensitization at five years of age, new findings show.

The risk was strongest in children whose mothers had a history of allergic disease, Dr. Valerie Verhasselt of the University Nice Sophia Antipolis in Nice, France, and colleagues found. These children were also more than three times as likely to develop asthma or allergic rhinitis compared to children without early HDM allergen exposure.

"This latter result suggests that a gene-environment interaction between familial asthma or allergy and Der p (Dermatophagoides pteronyssinus) 1 in the milk is necessary for increasing the risk of asthma and rhinitis," Dr. Verhasselt and her team say in their report, published online August 24 in the Journal of Allergy and Clinical Immunology.

Up to 80% of patients with allergic rhinitis and asthma have sensitization to allergens from Der p and Dermatophagoides farinae (Der f), the researchers note. Studies of interventions to reduce early-life exposure to HDM allergens have had mixed results, they add.

In previous research, Dr. Verhasselt and colleagues identified respiratory allergens from HDM in human breast milk, and showed that mice exposed to Der p in breast milk were more likely to have allergic sensitization. To investigate the association between early HDM allergen exposure and allergic disease in humans, the researchers looked at data from the French EDEN birth cohort on 255 mother-child pairs.

Two-thirds of the mothers had detectable levels of Der p 1 in their milk. The median Der p 1 level for the whole population was 52.1 pg/ml. Mothers with a history of asthma or allergies, those younger than 34 and those whose milk was collected in winter had higher median Der p 1 levels.

Children whose mothers had a history of allergy or allergies and high levels of Der p 1 (above the median) were more likely to have asthma or allergic rhinitis at five years of age compared to those born to mothers whose Der p 1 levels were lower than the median (odds ratio, 3.4; p=0.02).

IgE levels were assessed in 142 children. Those exposed to higher Der p 1 levels were more likely to have positive total IgE (adjusted OR, 3.87; p=0.003), though the increase in the odds of having Der p 1-specific IgE did not reach significance (aOR, 2.21; p=0.07).

"The data presented here highlight the need to be cautious in recommending early oral exposure to allergens," Dr. Verhasselt and colleagues write. "In contrast to antigens such as the egg antigen, ovalbumin, Der p allergens have strong intrinsic adjuvant properties due to Toll Like Receptor agonist and protease activities which may be responsible for the initiation of allergic immune responses."

In a telephone interview with Reuters Health, Dr. Verhasselt said that while breast milk does an excellent job of helping infants fight infectious disease, "there has not been enough time to select the perfect breast milk to prevent allergic disease."

Dr. Verhasselt and her team are now working on replicating the findings in cohorts from Japan, the Netherlands, and Australia, and are continuing animal studies to investigate possible interventions.

The results in no way suggest that women should stop breastfeeding and switch to formula in order to avoid allergic disease in their offspring, according to Dr. Verhasselt.

In fact, children can be exposed orally to HDM allergens independently of breastmilk, she pointed out, noting that she and her colleagues previously showed that HDM allergens are found in digestive fluids of healthy individuals. Breast milk contains components that help counteract deleterious effects of HDM allergen exposure, she said, while formula does not.

SOURCE: http://bit.ly/2cAOwPl

J Allergy Clin Immunol 2016.

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