**6.4 Correction of Th1/Th2 imbalance**

The development of food allergy is related to Th2-deviant immune status in the sensitization phase of AD [9]. Although IFN- has tolerogenic effects on pre-existing food allergy, the development or prevention of a food allergy is primarily associated with sensitization. IFN plays a role in preventing food allergy by correcting the Th1/Th2 imbalance [21].

### **6.5 Prevention of allergy provocation**

The diagnosis of food allergy and subsequent elimination diet of all possible allergenic foods is important to prevent further sensitization from repetitive allergy provocation. Repetitive allergy provocation and the resultant further Th2-polarization make patients more likely to develop additional allergies [2]. Sensitization to more food allergens, as well as aeroallergens, can occur with repeated allergy flares. It follows that allergy provocation by known allergens should be avoided to prevent further sensitization. For this reason, AD should be evaluated for repetitive allergy provocation and not simply the severity of AD. Furthermore, patients with mild AD should be treated early to prevent repeated allergic responses.

#### **6.6 IL-10 for the prevention of food sensitization**

Helminths induce generation of IL-10 in the gut and prevent sensitization to foods in mice [50]. Promotion of an IL-10-rich environment in the gut was investigated for its role in preventing or even treating food allergies. The prevention of food allergies by administering either an IL-10-secreting *Lactococcus lactis* [51] or an avirulant *Salmonella typhimurium* strain that promotes IL-10 secretion in the gut [52] was demonstrated. In this study, transiently expanded IL-10-secreting T cell populations played an important role in keeping the allergen-specific effector T cell responses in check. From these results, it was possible to explain how skin exposure to high doses of allergens led to a decreased immune response with subsequent allergen exposures [53].

### **6.7 Skin hydration**

Physical injury leads to a Th2-deviant status in the local skin and resultant allergic status (Fig. 2) [54]. These changes result in sensitization to simultaneously exposed allergens as described above. Dryness is one of the main causes of itching. For all aspects of AD symptoms, skin hydration is very important to prevent further sensitization through the skin.

Food Allergy in Atopic Dermatitis 247

dryness and injury caused by scratching contributes to repeated allergic responses (Fig. 2). In order to prevent sensitization to multiple allergens, use of food additives should be

First of all, I dedicate this manuscript to Yeahee Yoo, for her excellent support in finishing this work. Also, this work was supported by the grant of the Korean Ministry of Education, Science and Technology (The Regional Core Research Program/Chungbuk BIT Research-

IFA, IgE-mediated food allergy; NFA, non-IgE-mediated food allergy; TIFA, tolerance

Food allergy, IgE-mediated food allergy, Non-IgE-mediated food allergy, Tolerance, Oral

[3] Suh, K.Y., 2010. Food Allergy and Atopic Dermatitis: Separating Fact from Fiction.

[4] Jyonouchi, H., 2008. Non-IgE mediated food allergy, Inflammation and Allergy Drug

[5] Longo G, Barbi E, Berti I, et al. Specific oral tolerance induction in children with very severe cow's milk-induced reactions. J Allergy Clin Immunol 121:343-347, 2008. [6] Noh G, Lee SS. A pilot study of IFN--induced specific oral tolerance induction for IgE-

[7] Lee JH, Noh G, Noh J, Lee S, Choi WS, Kim HS, Lee K, Choi S, Jin H, Cho S, Lee S.

[8] Kim JS. Food Allergy: Diagnosis, Treatment, Prognosis, and Prevention. Pediatric Annals

[9] Lancour M. Acute infections in atopic dermatitis. A clue for a pathogenic role of a

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diseases? A follow-up study. Clinical and Molecular Allergy 2010;8: 8-19.

Nutrition and the Skin. Preedy VR (Ed). Wageningen, Netherlands: Wageningen

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Clinical characteristics of oral tolerance induction of IgE-mediated and non-IgEmediated food allergy using interferon gamma. Allergy and Asthma Proceedings ,

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[1] Bieber T. Atopic dermatitis. New England Journal of Medicine 2008;358:1483-1494. [2] Noh G, Lee JH, Lee SS. Food allergy and atopic dermatitis. In Handbook of Diet,

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**7. Acknowledgement** 

**8. Abbreviations** 

tolerance induction, IFN-

**Keywords** 

**9. References** 

Oriented University Consortium).

Fig. 2. Immunopathogenesis of sensitization through skin. Physical injury induced the release of thymus stromal lymphopoietin (TSLP) in the skin and subsequently IL-21 is released from Th2 cell by TSLP. By the multiple actions of IL-21, the skin is Th2-polarized. In this process, also many Th2-related cytokines are involved including IL-4, IL-5, IL-13, IL-16, IL-31, IL-32. Any allergens exposed simultaneously in this status, are sensitized in skin. If skin is sensitized by IgE-mediated allergy, skin prick test to sensitized allergens becomes positive, while if skin is sensitized by non-IgE-mediated allergy, allergy patch test may become positive with the development of atopic dermatitis.

#### **6.8 Restriction of food additives**

Food additives play a role in food allergy and AD by acting as pseudoallergens [25]. Ingestion of food additives leads to dryness and itching [24]. Physical injury by scratching due to dryness and itching results in sensitization to additional allergens [54]. This cycle of

Fig. 2. Immunopathogenesis of sensitization through skin. Physical injury induced the release of thymus stromal lymphopoietin (TSLP) in the skin and subsequently IL-21 is released from Th2 cell by TSLP. By the multiple actions of IL-21, the skin is Th2-polarized. In this process, also many Th2-related cytokines are involved including IL-4, IL-5, IL-13, IL-16, IL-31, IL-32. Any allergens exposed simultaneously in this status, are sensitized in skin. If skin is sensitized by IgE-mediated allergy, skin prick test to sensitized allergens becomes positive, while if skin is sensitized by non-IgE-mediated allergy, allergy patch test may

Food additives play a role in food allergy and AD by acting as pseudoallergens [25]. Ingestion of food additives leads to dryness and itching [24]. Physical injury by scratching due to dryness and itching results in sensitization to additional allergens [54]. This cycle of

become positive with the development of atopic dermatitis.

**6.8 Restriction of food additives** 

dryness and injury caused by scratching contributes to repeated allergic responses (Fig. 2). In order to prevent sensitization to multiple allergens, use of food additives should be restricted.
