Epsilon germ‐line and IL‐4 transcripts are expressed in human intestinal mucosa and enhanced in patients with food allergy

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Abstract
Background:  The mechanisms of gastrointestinal (GI) food allergy (FA) are poorly understood. Immunoglobulin E (IgE) is increased in stools from patients with FA, as well as the number of cells carrying IgE in intestinal mucosa, but the origin of IgE production remains unknown. To investigate a local production of IgE in intestine, we analysed the levels of transcripts for epsilon germ‐line (εGT), and potential regulators of IgE production, IL‐4, IL‐13, IFN‐γ, IL‐4Rα, STAT6 and FcεRIα in intestinal mucosa of adult patients with FA.Methods:  Endoscopic biopsies were obtained from the caecum of 25 patients with FA and 14 control patients. The levels of εGT, IL‐4, IL‐13, IFN‐γ, IL‐4Rα, STAT6 and FcεRIα mRNA were analysed by real‐time RT‐PCR and compared with unpaired nonparametric Mann–Whitney test.Results:  The mean εGT transcript level in caecum was increased in FA patients compared with control patients (P < 0.05). IL‐4 mRNA expression was also increased in FA patients (P < 0.05), whereas mRNA expression for IL‐13, IFN‐γ, IL‐4Rα, STAT6 and FcεRIα mRNA expression was not altered. However, the ratio of IL‐4 mRNA/IFN‐γ mRNA was significantly increased in FA patients (P < 0.05). No correlation was observed between εGT transcripts expression in intestinal mucosa and total IgE levels in serum.Conclusions:  This study shows that (i) εGT transcripts are expressed in human intestinal mucosa; (ii) εGT and IL‐4 transcripts are increased in caecal mucosa from patients with FA. These results suggest local production of IgE in intestine that might be of importance for inflammatory reactions in the GI tract.