_applied sciences_  
_Article_  
Establishment of an Epicutaneously Sensitized Murine Model of Shellfish Allergy and Evaluation of Skin Condition by  
Raman Microscopy  
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and are therefore most common in adults [6]. Food allergies that develop in adulthood are more difficult to achieve clinical tolerance than those that develop in childhood; therefore, the only way to prevent allergic reactions in affected adults is to avoid consuming the allergen. Food allergy is associated with poorer quality of life for both the individual with the allergy, as well as their family.  
One of the primary shellfish allergens is tropomyosin, a protein that forms thin myofibrils and constitutes 20% of the total protein in shrimp. Tropomyosin is present in many invertebrate species including other crustaceans (lobster, crab), mollusks (mussels, oysters, scallops, octopus, squids, snails, clams), as well as terrestrial arthropods (cockroaches and mites) [7]. As allergic cross-reactivity has been confirmed between tropomyosins from these sources, shellfish allergy patients must also exercise caution with these foods, including insect foods, which are being developed to address the food shortage crisis [6].  
The mechanism leading to the onset of food allergies was thought to partly involve immature digestive function, as food allergies are more common in infancy [5]. However, recent research has demonstrated the importance of epicutaneous antigen exposure in the mechanism of sensitization [8]. Atopic dermatitis involving skin barrier damage is now recognized as a well-known risk factor for food allergies [9; 10]. In addition, because of the cross-reactivity of tropomyosin between shrimp, cockroaches, and dust mites, skin sensitization to tropomyosin derived from cockroaches and mites may lead to oral intolerance to shrimp, leading to allergic reactions, which may explain the high prevalence of shellfish allergy in tropical and subtropical regions where mite sensitization is common [3]. We hypothesized that epicutaneous sensitization plays a significant role in adult-onset shellfish allergy, as the digestive tract has well-developed. To date, a mouse model of shrimp allergy by epicutaneous sensitization has not been reported [11]. An objective of the present study was to determine whether exposure to shrimp antigens via the skin can cause shellfish allergy.  
Numerous studies have described molecules associated with the dysfunction of the skin barrier. For example, mutations in the gene encoding filaggrin protein are associated with the development of atopic dermatitis [12]. Reduced ceramide has also been associated with food allergies in patients with atopic dermatitis [10]. However, lipid reduction and other slight molecular changes cannot be detected morphologically using histopathological techniques. Confocal Raman microscopy is a non-invasive technique that uses non-visible light to provide information on the molecular structure of the skin, and its use has recently become common in dermatological research [13]. Confocal Raman microscopy enables the estimation of substances by measuring laser excitation-induced vibrational modes of chemical molecules, which have unique values for each functional group [14]. The use of confocal Raman microscopy could provide for early detection of changes in the skin that lead to sensitization, thereby helping prevent food allergies associated with epicutaneous sensitization. The aim of this study was to generate a mouse model of shrimp allergy via epicutaneous sensitization and elucidate the changes in the skin that cause sensitization using Raman microscopy.