Published Online: February 26, 2016
Atopic dermatitis/eczema (AD) is one of the earliest features of allergies in children and there is a strong association of severe infantile AD with food allergy. Mouse studies have shown skin exposure to foods is more likely to trigger food allergy than oral exposure and AD-related gene defects are strongly associated with food allergy.
In a recently published report in The Journal of Allergy and Clinical Immunology (JACI) Kelleher and colleagues report data from the Irish BASELINE birth cohort that show simple, non-invasive measurements of skin barrier function in the first few days of life predict food allergy at 2 years. BASELINE is an unselected birth cohort in Cork, Ireland, funded by the National Childrens Research Centre in Ireland and the UK Food Standards Agency. Recruited infants had Transepidermal Water Loss (TEWL) measured non-invasively at 3 time points in the first year of life: day 2 of life in the maternity hospital, 2 months and 6 months. All suspected cases of food allergy were assessed by formal food challenge at 2 years by researchers who were blind to the TEWL data.
1902 Newborns were recruited and 1260 had food allergy assessment and tests at 2 years of age. Food allergy was challenge-proven in 56 children (4.45%) Newborns with allergic parents and whose neonatal TEWL was in the the top 25% of readings (>9gwater/m2/hr) were 18 times more likely to have food allergy at 2 years than children with TEWL in the lowest 25%. The link of high neonatal TEWL with later food allergy was seen even when the children did not develop AD in the first two years, suggesting it is the physical barrier deficit itself rather than the actual presence of visible AD or intervening AD-related inflammation that is most important in facilitating early, abnormal immune responses to food allergens such as peanut, egg and milk.
These findings, using simple, non-invasive measurements support and extend previous human and mouse studies linking AD, epicutaneous sensitization to food and the development of food allergy. They suggest that the current research focus on skin barrier preservation in the first few months of life to prevent AD in the the first year may have additional and longer term benefits in food allergies and possibly asthma, as they may prevent allergy signals starting in the defective skin of very young babies, even before they get AD. This will need to to be carefully tested in clinical trials, but it offers hope that the onset of lifelong allergic conditions, which has reached epidemic proportions, may be amenable to simple, early-life preventive stategies emerging at present.
The Journal of Allergy and Clinical Immunology (JACI) is an official scientific journal of the AAAAI, and is the most-cited journal in the field of allergy and clinical immunology.