Mechanisms by Which Atopic Dermatitis Predisposes to Food Allergy and the Atopic March

The Atopic march denotes the progression from atopic dermatitis (AD) to the development of other allergic disorders such as immunoglobulin (Ig) E-mediated food allergy, allergic rhinitis and asthma in later childhood. There is increasing evidence from prospective birth cohort studies that early-onset AD is a risk factor for other allergic diseases or is found in strong association with them. Animal studies now provide mechanistic insights into the pathways that may be responsible for triggering the progression from the skin barrier dysfunction seen in AD to epicutaneous sensitization, food allergy and allergic airway disorders. Recent large randomized controlled trials have demonstrated the efficacy of early interventions targeted at AD and food allergy prevention. These show great promise for research into future strategies aimed at prevention of the atopic march.

Novel strategies in immunotherapy for allergic diseases

Conventional immunotherapy (IT) for optimal control of respiratory and food allergies has been fraught with concerns of efficacy, safety, and tolerability. The development of adjuvants to conventional IT has potentially increased the effectiveness and safety of allergen IT, which may translate into improved clinical outcomes and sustained unresponsiveness even after cessation of therapy. Novel strategies incorporating the successful use of adjuvants such as allergoids, immunostimulatory DNA sequences, monoclonal antibodies, carriers, recombinant proteins, and probiotics have now been described in clinical and murine studies. Future approaches may include fungal compounds, parasitic molecules, vitamin D, and traditional Chinese herbs. More robust comparative clinical trials are needed to evaluate the safety, clinical efficacy, and cost effectiveness of various adjuvants in order to determine ideal candidates in disease-specific and allergen-specific models. Other suggested approaches to further optimize outcomes of IT include early introduction of IT during an optimal window period. Alternative routes of administration of IT to optimize delivery and yet minimize potential side effects require further evaluation for safety and efficacy before they can be recommended.

How Different Parts of the World Provide New Insights Into Food Allergy

The prevalence and patterns of food allergy are highly variable in different parts of the world. Differences in food allergy epidemiology may be attributed to a complex interplay of genetic, epigenetic, and environmental factors, suggesting that mechanisms of food allergy may differ in various global populations. Genetic polymorphisms, migration, climate, and infant feeding practices all modulate food allergy risk, and possibly also the efficacy of interventions aimed at primary prevention of food allergy development. Approaches to diagnosis, treatment, and prevention of food allergy should thus be tailored carefully to each population's unique genetic and environmental make-up. Future research in the context of food allergy prevention should focus on elucidating factors determining differential responses between populations.