Nuts 'n' guts: transport of food allergens across the intestinal epithelium

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http://apallergy.org/DOIx.php?id=10.5415/apallergy.2013.3.4.257

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Asia Pac Allergy. 2013 Oct;3(4):257-265. English.
Published online 2013 October 31.  http://dx.doi.org/10.5415/apallergy.2013.3.4.257
Copyright © 2013. Asia Pacific Association of Allergy, Asthma and Clinical Immunology.
Nuts 'n' guts: transport of food allergens across the intestinal epithelium
Dwan Price,1,2 Leigh Ackland,1 and Cenk Suphioglu2
1Centre for Cellular and Molecular Biology, School of Life and Environmental Sciences, Faculty of Science, Engineering and Built Environment, Deakin University, Burwood, VIC 3125, Australia.
2NeuroAllergy Research Laboratory, School of Life and Environmental Sciences, Faculty of Science, Engineering and Built Environment, Deakin University, Geelong, VIC 3216, Australia.

Correspondence: Cenk Suphioglu. NeuroAllergy Research Laboratory, School of Life and Environmental Sciences, Faculty of Science, Engineering and Built Environment, Deakin University, 75 Pigdons Rd., Waurn Ponds, VIC 3216, Australia. Tel: +61-3-5227-2886, Fax: +61-3-5227-1040, Email: cenk@deakin.edu.au
Received September 23, 2013; Accepted October 04, 2013.

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.


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Abstract

The increase in the incidence of food allergy is a growing problem for the western world. This review will focus on the findings from several macromolecular epithelial transport experiments and drug permeability studies to provide a recent comprehension of food allergen intestinal epithelial cell transport and the allergen-epithelial relationship. Specifically, this review will aim to answer whether allergens can permeate the intestinal barrier directly via intestinal epithelial cells, and whether this mode of transport affects downstream immune reactions. By improving our understanding of the interactions which take place during exposure of food allergens with the intestinal epithelium, we can begin to understand whether the epithelial barrier plays a major role in the allergic sensitization process rather than simply restricting the entry of allergens to the underlying lamina propria.

Keywords: Food allergy, Peanut, Intestinal epithelial cell, Cell tight junctions, Cell barrier integrity, Peyer's patch.

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INTRODUCTION
Today, it's not uncommon to hear of allergy to common foods such as egg, milk, seafood, many fruits, tree nuts and in particular peanuts. Peanuts in particular are the highest contributor of anaphylactic deaths after ingestion of a food allergen [1]. Only trace amounts of peanut protein can trigger an allergic response [2]. It is for this reason that 'nut-free' schools, kindergartens and childcare facilities is nowadays common practice. The food allergy epidemic continues to lead the allergy and immunology zeitgeist, and will remain at the forefront of allergist investigation until a definitive understanding of food allergy cause and manifestation is achieved.

Food allergy is a growing problem for the western world. Recently, an Australian study involving a small population of children; referred to a specialist allergy clinic within the Australian Capital Territory, revealed that the incidence of peanut sensitivity in children within Australia has more than doubled since 1995 [3]. A 2009 study-conducted in the United Kingdom by Venter et al. [4], compared the prevalence of peanut allergy for three different cohorts of children A, B, and C whom were either born in 1989, 1994-1996 and 2001-2002, respectively. Peak peanut sensitisation was observed in cohort B at 3.3%, an increase to that observed in 1989 (1.3%). Interestingly, cohort C observed statistically non-significant decrease at 2.0%. Similarly, another study revealed that the prevalence of peanut allergy has almost doubled from 0.24 per 1,000 patients in 2001 to 0.51 per 1,000 patients in 2005 as observed by an increase in diagnoses by general practitioners [5]. Other studies have also demonstrated similar findings [6,7]. This rising trend highlights the importance of global therapeutic intervention and research targeted at combating the rising prevalence of peanut allergy.

The growing incidence of peanut allergy throughout westernised populations; and the limited available therapeutic intervention, purports the development of additional effective treatments to mediate the condition. In addition, further study into the mechanism of peanut allergy should be of global priority, to prevent greater economic burden in the future. Therefore, the aim of this review will focus on a relatively unexplored aspect of the allergen sensitization process-the initial passage through the intestinal epithelium. The findings from several macromolecular epithelial transport experiments and drug permeability studies have been collated to provide a recent comprehension of food allergen intestinal epithelial cell (IEC) transport. IEC allergen transport is relatively unaddressed in the literature. Thus, expanding our knowledge in this field will enhance our understanding of the allergen sensitization process. To address this, our review will briefly introduce the allergenic characteristics of the major allergenic food peanut, and the process by which an individual becomes sensitized to peanuts: from allergen to allergy. From here, the review will explore the various pathways that allergens may cross the intestinal mucosa via IEC. Specifically, this review will aim to answer whether peanut allergens are likely to permeate the intestinal barrier via IEC.