Plain language summary
Inflammatory bowel disease (IBD) is an umbrella term incorporating ulcerative colitis (UC) and Crohn’s disease (CD). The exact reasons for the development of IBD are still being debated, however food allergy has been implicated. Diagnosis of food allergy is normally performed looking at the body’s immediate immune response, however the delayed immune response may be of importance in IBD. This study of 301 patients with IBD and 178 healthy controls aimed to look at the delayed immune response of individuals with IBD following the introduction of certain foods. It also looked at the efficacy of a drug treatment, infliximab (IFX) on this immune response. The results showed that the delayed immune response to egg, milk, wheat, corn, rice, tomato, codfish, and soya was increased in those with CD compared to those with UC and healthy control. Infliximab treatment was effective in suppressing this immune response in individuals with CD. It was concluded that in individuals with IBD, measuring the delayed immune response to foods may be an important diagnosis and management tool. This study could be used by healthcare professionals to understand that measuring the immediate immune response to certain foods in individuals with IBD, may not be sufficient. Measuring the delayed immune response in combination with the immediate immune response may give a better picture of foods which should be avoided in those with IBD. Infliximab treatment may be an effective treatment in patients with IBD and a delayed immune response to certain foods.
Objective Dietary antigens are common luminal antigens in the gastrointestinal tract and have been considered to contribute to the pathogenesis of inflammatory bowel disease (IBD). We analyzed the levels of food-specific IgGs against a variety of dietary antigens, explored the clinical relevance of food allergy to the pathogenesis of IBD, and investigated whether or not infliximab (IFX) treatment could regulate the immune responses induced by dietary antigens. Methods A total of 301 IBD patients, including 201 patients with Crohn's disease (CD) and 100 patients with ulcerative colitis (UC), were recruited, and their serum food-specific IgGs against 14 food antigens were detected by a semi-quantitative enzyme linked immunosorbent assay (ELISA). Total serum IgG and IgE levels were measured by immunonephelometry and ﬂuorescent enzyme immunoassay, respectively. Simultaneously, the relevant medical records and clinical data were collected for further analyses. Results Food-specific IgGs against egg, milk, wheat, corn, rice, tomato, codfish, and soybean antigens were found to be significantly increased in the sera of CD patients compared with UC patients and healthy controls (p<0.01). The levels of total serum IgG and IgE were also significantly higher in CD patients than in healthy controls (p<0.01). The titers of corn- and tomato-specific IgGs were found to be significantly correlated with total serum IgG in CD patients (p<0.05), while the titers of egg-, milk-, and wheat-specific IgGs were correlated with total serum IgE (p<0.05). Interestingly, IFX therapy was able to down-regulate the food-specific IgG-mediated immune response markedly in active CD patients. Conclusion Food-specific IgGs against egg, milk, wheat, corn, rice, tomato, codfish, and soybean are highly increased in the sera of CD patients. IFX treatment was able to down-regulate the levels of food-specific IgGs by suppressing intestinal inflammation and promoting mucosal healing. Therefore, food-specific IgGs may serve as an important approach in the diagnosis and management of food allergy in IBD.