Hypoallergenicity assessment of an extensively hydrolyzed whey‐protein formula in cow’s milk allergic infants

Background Extensively hydrolyzed formulas are recommended for the dietary management of infants with cow's milk allergy (CMA). Objectives Hypoallergenicity, growth, and gastrointestinal (GI) tolerability of a new extensively hydrolyzed whey-protein formula (eHWF) in CMA children were assessed. Methods In this prospective, randomized, international, multi-center study (Trial NL3889), 34 children with confirmed CMA (74% IgE-mediated) underwent a double-blind, placebo-controlled food challenge (DBPCFC) with an eHWF developed with non-porcine enzymes, supplemented with prebiotic short-chain galacto- and long-chain fructo-oligosaccharides (0.8 g/L, ratio 9:1), arachidonic acid (0.35/100 g), and docosahexaenoic acid (0.35/100 g). If tolerant to the eHWF, children participated in a 7-day open food challenge with this eHWF. Anthropometrics and GI tolerability were assessed in an optional 16-weeks follow-up. Results Of the 34 children who started the DBPCFC with the eHWF, 25 subjects (19 boys, mean age: 61 weeks, 18 with IgE-mediated CMA) completed the DBPCFC and 7-day open challenge without major protocol deviations and tested negative at both challenges. One child experienced a late moderate eczematous allergic reaction in the optional follow-up period, indicating the need for close monitoring of subjects starting new formula. Weight and length gain followed the World Health Organization growth curves. Changes in frequency and consistency of stools upon test formula intake were transient. Conclusions The newly developed eHWF is a suitable option in CMA treatment as all subjects tolerated the product. This result is in line with the international criteria for hypoallergenicity (American Academy of Pediatrics) that state that more than 90% of CMA children must tolerate the formula. Use of the formula is also associated with normal growth curves and GI tolerability

Neuroimmune regulation of inflammatory responses in inflammatory bowel disease

The term inflammatory bowel disease (IBD) is used to describe chronic inflammatory conditions of the gastro-intestinal tract. Patients suffer from abdominal pain, diarrhea, rectal bleeding and a substantial personal burden. The etiology of IBD is gradually being unraveled but remains a complex interaction between environmental, immunological and genetic factors. Mast cells and nerves can be found in close association in the intestine and the connection increases during inflammation. Understanding of the interaction between mast cells and nerves in IBD could help to provide new insights in the pathophysiology of this disorder. In this thesis a murine model was setup and validated to study the role of mast cells and nerves in the development of IBD by inducing a hypersensitivity response in the colon. This reaction is accompanied with mast cell proliferation and activation, infiltration of inflammatory cells, hypertrophy of lymphoid structures and diarrhea. The importance of mast cells was established by the observation that the responses could not be induced in mast cell-deficient (WBB6F1 W/Wv) mice. Furthermore, treatment with specific antibodies directed against the mast cell-derived pro-inflammatory cytokine TNF? could also abolish the characteristics for the response. A role for nerve-derived neuropeptide substance P was established by treatment with an antagonist against its specific receptor, NK1. Traditionally, mast cells are involved in allergic reactions and get activated by cross-linking of IgE molecules bound on the mast cell surface. However, not all hypersensitivity responses are associated with increased circulating levels of IgE. It was demonstrated that antigen-specific immunoglobulin-free light chains (IgLC) was capable of inducing mast cell activation by itself providing evidence for mast cell activation in non-IgE-mediated disorders. In the newly described murine colitis model a prominent role is established for IgLC by demonstrating that treatment with the specific antagonist for IgLC led to the abrogation of the hypersensitivity response in the colon. Since mast cells and nerves are highly associated and both described to be involved in hypersensitivity reactions, a role for IgLC in inducing neuronal activation was hypothesized. In this thesis it is described that IgLC can bind specifically to mouse dorsal root ganglion (DRG) neurons. Subsequent activation with the corresponding antigen resulted in a gradual increase in intracellular Ca2+ suggesting that the neuron gets activated. These data reveal a new physiological role for IgLC in eliciting antigen-specific neuronal activation and thereby amplification of the inflammatory response. Clinical relevance for IgLC is provided by demonstrating that serum concentrations of IgLC are increased in patients suffering from IBD and another gastro-intestinal disorder, irritable bowel syndrome. The data obtained in this thesis present new insight in the mast cell-nerve interactions in gastro-intestinal disorders and the novel murine model supplies a helpful tool to elucidate on the mechanism behind this interaction

Dietary haem stimulates epithelial cell turnover by downregulating feedback inhibitors of proliferation in murine colon

Objective: Colon cancer is a leading cause of cancer deaths in Western countries and is associated with diets high in red meat. Haem, the iron-porphyrin pigment of red meat, induces cytotoxicity of gut contents and damages the colon surface epithelium. Compensatory hyperproliferation leads to epithelial hyperplasia which increases the risk of colon cancer. The aim of this study was to identify molecules signalling from the surface epithelium to the crypt to initiate hyperproliferation upon stress induced by haem. Methods: C57Bl6/J mice (n=9/group) received a 'westernised' control diet (40 en% fat) with or without 0.5 mmol/g haem for 14 days. Colon mucosa was used to quantify cell proliferation and for microarray transcriptome analysis. Gene expression profiles of surface and crypt cells were compared using laser capture microdissection. Protein levels of potential signalling molecules were quantified. Results: Haem-fed mice showed epithelial hyperproliferation and decreased apoptosis, resulting in hyperplasia. Microarray analysis of the colon mucosa showed 3710 differentially expressed genes (false discovery rate (q