Clinical efficacy and immunological changes subjacent to egg oral immunotherapy.

BACKGROUND: Evidence of the efficacy of food oral immunotherapy (OIT) is not robust enough to change clinical practice from current standard management. Furthermore, the immunologic changes underlying food desensitization are unknown. OBJECTIVE: To establish the immunologic basal status and differences between an egg-allergic group of children and a population of nonallergic children and to investigate the safety and efficacy of a specific egg OIT protocol to induce clinical desensitization and the associated immune responses. METHODS: Children with or without egg allergy were recruited. Allergic subjects underwent an OIT protocol based on weekly doses of egg protein and a maintenance phase. Immune profile and changes in all subjects were investigated by measuring T-helper cells types 1 and 2 (TH1 and TH2) and T-regulatory cytokines and transcription factors and egg-specific IgE and IgG4 levels. RESULTS: At baseline, a significantly lower production of ovalbumin-specific interleukin (IL)-10 and tumor necrosis factor-α and a trend toward higher IL-5 and IL-13 were found in allergic children. The egg OIT protocol enabled 60% of them to ingest 32 mL of egg white. Significant increases in egg-specific IgG4 levels and IL-10 production, with a trend toward lower IL-5 and IL-13 and higher tumor necrosis factor-α and interferon-γ levels, and significant decreases in egg-specific IgE concentration were observed. CONCLUSION: Egg-allergic individuals display a bias toward TH2 type cytokine production and decreased TH1 and IL-10 responses compared with nonallergic individuals. The OIT protocol was safe and effective in inducing egg desensitization, leading to a shift in the immune profile of allergic individuals toward a nonallergic phenotype.

Maternal Antiasthma Simplified Herbal Medicine Intervention therapy prevents airway inflammation and modulates pulmonary innate immune responses in young offspring mice.

BACKGROUND: Maternal asthma is a risk factor for asthma in offspring; however, transmission of the risk for allergic asthma without direct offspring sensitization has not been explored. OBJECTIVE: To determine whether offspring from mothers with ovalbumin (OVA)-sensitized asthma would develop airway disease at first-ever exposure to OVA and whether preconception maternal treatment with the Antiasthma Simplified Herbal Medicine Intervention (ASHMI) or dexamethasone (DEX) could modify this risk in offspring. METHODS: Female BALB/c mice (F0) with OVA-induced asthma were generated using established protocols. Mice with asthma were treated with ASHMI, DEX, or water for 6 to 7 weeks. Naive mice served as controls. Subsequently, mice were mated. Twelve-day-old F1 offspring received 3 consecutive intranasal low- or high-dose OVA exposures without sensitization. Forty-eight hours later, airway inflammation, mucus hypersecretion, serum antibodies, and cytokines were evaluated. RESULTS: Offspring from OVA-sensitized mothers, but not naive mothers, showed eosinophilic and neutrophilic airway inflammation, and mucus hyperplasia after OVA exposure and he presence of OVA-specific IgG1 and IgG2a. Offspring of ASHMI- and DEX-treated mothers showed decreased airway inflammation and mucus hypersecretion after low-dose OVA (P < .05-.001 for the 2 comparisons vs offspring of OVA/Sham mothers). Offspring of ASHMI-treated, but not DEX-treated, mothers were protected after the high-dose OVA challenge (P < .05-.01 vs offspring OVA/Sham). Maternal ASHMI therapy was associated with increased IgG2a (P < .01 vs offspring of OVA/Sham mothers) and decreased bronchoalveolar lavage fluid CXCL-1 and eotaxin-1 levels (P < .01 and P < .05, respectively, vs offspring of OVA/Sham mothers). CONCLUSION: Offspring of mothers with OVA-induced asthma developed airway inflammation and mucus to first-ever OVA exposure without prior sensitization. Maternal therapy with ASHMI was superior to DEX in decreasing offspring susceptibility to airway disease and could be a strategy to lower asthma prevalence.

In vitro digestibility of bovine ß-casein with simulated and human oral and gastrointestinal fluids. Identification and IgE-reactivity of the resultant peptides.

Stability during digestion is considered an important feature in determining the allergenicity of food proteins. This study aimed to provide an immunological characterisation of the digestion products of the major cow's milk allergen ß-casein (ß-CN) produced by in vitro orogastrointestinal hydrolysis with simulated and human digestive fluids. ß-CN was unaffected by oral digestion, but quickly broke down during the early stages of gastric digestion. The degradation with human fluids was faster than that with commercial enzymes. There were similarities in the peptide patterns of the hydrolysates produced in both models, showing 20 peptides in common after gastric digestion. After gastroduodenal digestion, the human fluids gave less numerous and shorter peptides. The IgE binding of most of the individual sera used to the hydrolysates produced with simulated and human fluids increased at the end of the gastric phase and decreased when the duodenal digestion was completed. Two IgE-binding synthetic peptides: ß-CN (57-68) and ß-CN (82-93), which matched fragments released by ß-CN following in vitro digestion with simulated and human fluids, consisted of the most immunoreactive areas of the protein. The similarities found between the in vitro simulated digestion system and that using human digestive fluids suggest that the former would provide a reasonably good estimation of the potential allergenicity of protein digests.

Identification of IgE-binding peptides in hen egg ovalbumin digested in vitro with human and simulated gastroduodenal fluids.

The digestibility of the major egg allergen ovalbumin (OVA, Gal d 2) with human and simulated digestive fluids was assessed. Degradation of OVA was faster when treated with human fluids, particularly following duodenal digestion, leading to gastrointestinal digests with lower IgE binding. Gastric digestion with both systems yielded 52 identical cleavage sites and a similar peptide pattern with 47 peptides in common. Subsequent duodenal digestion showed that the human fluid released fewer and shorter peptides. Several high-frequency IgE-binding epitopes were detected among the fragments of molecular mass lower than 3 kDa identified in the digests: OVA (141-154) and OVA (164-176) in the gastrointestinal digests produced with human fluids; and OVA (125-134), OVA (159-172), OVA (141-154), OVA (188-198), OVA (326-336), and OVA (370-385) in the gastrointestinal digests produced with simulated fluids. The high binding frequency of the fragment OVA (370-385), which reacted with 80% of the sera from allergic patients used, was noteworthy.

Mechanisms underlying differential food allergy response to heated egg.

BACKGROUND: Egg white proteins are usually subjected to heating, making them edible for the majority of children with egg allergy. OBJECTIVE: We sought to investigate the underlying mechanisms responsible for the reduced allergenicity displayed by heat-treated egg white allergens. METHODS: C3H/HeJ mice were orally sensitized with ovalbumin (OVA) or ovomucoid and challenged with native or heated proteins to evaluate their allergenicity. Immunoreactivity was assessed by immunoblotting using sera from children with egg allergy. In vitro gastrointestinal digestion of native and heated OVA and ovomucoid was studied by SDS-PAGE and liquid chromatography. Intestinal uptake of intact native and heated OVA and ovomucoid by human intestinal epithelial (Caco-2) cells was investigated. Rat basophil leukemia cells passively sensitized with mouse serum and human basophils passively sensitized with serum from children with egg allergy were used to assess the effector cell activation by heated, digested, and transported OVA and ovomucoid. RESULTS: Heated OVA and ovomucoid did not induce symptoms of anaphylaxis in sensitized mice when administered orally. Heating did not completely destroy IgE-binding capacity of OVA or ovomucoid but enhanced in vitro digestibility of OVA. Digestion of both OVA and ovomucoid diminished mediator release in rat basophil leukemia assay and basophil activation. Heating of allergens prevented transport across human intestinal epithelial cells in a form capable of triggering basophil activation or T-cell activation. CONCLUSION: Heat treatment reduces allergenicity of OVA and ovomucoid. This is partially a result of the enhanced gastrointestinal digestibility of heated OVA and the inability of heated OVA or ovomucoid to be absorbed in a form capable of triggering basophils.

Application of mass spectrometry to the characterization and quantification of food-derived bioactive peptides.

Biologically active peptides are of particular interest in food science and nutrition because they have been shown to play different physiological roles, including antihypertensive, opioid, antimicrobial, and immunostimulating activities. Because these peptides are generated by protein hydrolysis or fermentation, they can represent only minor constituents in a highly complex matrix and therefore, identification of biologically active peptides in food matrixes is a challenging task in food technology. In this context, mass spectrometry (MS) has developed into a necessary tool to assess quality and safety of food and, more recently, to determine the presence and behavior of functional components such as these bioactive peptides. This review highlights the existing methods based on MS to identify, characterize, and quantify food-derived biologically active peptides, taking into account the different ionization sources used for the analysis of these high-value food components. The quantitative determination of bioactive peptides in food products or biological fluids is also discussed.

Protective effect of milk peptides: antibacterial and antitumor properties.

There is no doubt that milk proteins provide excellent nutrition for the suckling. However, apart from that, milk proteins can also exert numerous physiological activities benefiting the suckling in a variety of ways. These activities include enhancement of immune function, defense against pathogenic bacteria, viruses, and yeasts, and development of the gut and its functions. Besides the naturally occurring, biologically active proteins present in milk, a variety of bioactive peptides are encrypted within the sequence of milk proteins that are released upon suitable hydrolysis of the precursor protein. A large range of bioactivities has been reported for milk protein components, with some showing more than one kind of biological activity (Korhonen & Pihlanto, 2006). This chapter reviews the most important antimicrobial and antitumor peptides derived from milk proteins, especially those that may have a physiological significance to the suckling neonate. Antimicrobial peptides present in milk that are not derived from milk proteins are also considered. Special attention is given to the generation of these peptides by the action of different proteolytic enzymes and the origin of these enzymes since, if present in the digestive tract, it is likely that the peptides might play a role in the host defense system. Finally, the most relevant in vivo studies carried out with this kind of bioactive peptides are discussed.