Allergen-specific antibody and cytokine responses, mast cell reactivity and intestinal permeability upon oral challenge of sensitized and tolerized mice

Intermittent fasting protects against food allergy in a murine model via regulating gut microbiota

Background

The prevalence of food allergy (FA) is increasing. Decreases in the diversity of gut microbiota may contribute to the pathogenesis of FA by regulating IgE production of B cells. Intermittent fasting (IF) is a popular diet with the potential to regulate glucose metabolism, boosting immune memory and optimizing gut microbiota. The potential effect of long-term IF on the prevention and treatment of FA is still unknown.

Methods

Two IF protocols (16 h fasting/8 h feeding and 24 h fasting/24 h feeding) were conducted on mice for 56 days, while the control mice were free to intake food (free diet group, FrD). To construct the FA model, all mice were sensitized and intragastrical challenged with ovalbumin (OVA) during the second half of IF (day 28 to day 56). Rectal temperature reduction and diarrhea were recorded to evaluate the symptoms of FA. Levels of serum IgE, IgG1, Th1/Th2 cytokines, mRNA expression of spleen T cell related transcriptional factors, and cytokines were examined. H&E, immunofluorescence, and toluidine blue staining were used to assess the structural changes of ileum villi. The composition and abundance of gut microbiota were analyzed by 16srRNA sequencing in cecum feces.

Results

The diarrhea score and rectal temperature reduction were lower in the two fasting groups compared to the FrD groups. Fasting was associated with lower levels of serum OVA-sIgE, OVA-sIgG1, interleukin (IL)-4 and IL-5, and mRNA expression of IL-4, IL-5, and IL-10 in the spleen. While no significant association was observed in interferon (IFN)-γ, tumor necrosis factor (TNF)-α, IL-6, IL-2 levels. Less mast cell infiltration in ileum was observed in the 16h/8h fasting group compared to the FrD group. ZO-1 expression in the ileum of the two fasting groups was higher in IF mice. The 24h/24h fasting reshaped the gut microbiota, with a higher abundance of Alistipes and Rikenellaceae strains compared to the other groups.

Conclusion

In an OVA-induced mice FA model, long-term IF may attenuate FA by reducing Th2 inflammation, maintaining the integrity of the intestinal epithelial barrier, and preventing gut dysbiosis.

The Interaction of Food Allergy and Diabetes: Food Allergy Effects on Diabetic Mice by Intestinal Barrier Destruction and Glucagon-like Peptide 1 Reduction in Jejunum

The increase in food allergies and diabetes leads to the assumption that they are related. This study aimed to (1) verify the interaction between food allergy and diabetes and (2) explore the potential mechanisms by which food allergy promotes diabetes. Female BALB/c mice were grouped into a control group (CK), an ovalbumin-sensitized group (OVA), a diabetes group (STZ), and a diabetic allergic group (STZ + OVA) (Mice were modeled diabetes with STZ first, then were given OVA to model food allergies), and an allergic diabetic group (OVA + STZ) (Mice were modeled food allergies with OVA first, then were given STZ to model diabetes). The results showed that OVA + STZ mice exhibited a more serious Th2 humoral response, and they were more susceptible to diabetes. Furthermore, when the OVA + STZ mice were in the sensitized state, the intestinal barrier function was severely impaired, and mast cell activation was promoted. Moreover, we found that the effect of food allergy on diabetes is related to the inhibition of GLP-1 secretion and the up-regulation of the PI3K/Akt/mTOR/NF-κB P65 signaling pathway in the jejunum. Overall, our results suggest that food allergies have interactions with diabetes, which sheds new light on the importance of food allergies in diabetes.

Retinoic Acid Correlates with Reduced Serum IL-10 And TGF-β in Allergic Rhinitis

Background

Retinoic acid (RA) plays a key role in naïve T cell differentiation into FOXP3+ Treg cell in the respiratory airways. The present study aims to investigate RA and Treg-related cytokine serum levels, salivary IgA levels, FOXP3 and IL-4 gene expression, and the relationships between RA serum levels and Treg-related cytokines in allergic rhinitis (AR) patients and healthy controls.

Methods

Salivary IgA and serum IgE, RA, IL-10, and TGF-β concentrations were measured by ELISA in 37 AR patients and 30 age- and sex-matched healthy controls.

Results

IL-10 and TGF-β concentrations were significantly less in AR patients than in healthy controls (p< 0.01 and P< 0.0001, respectively). Salivary IgA was significantly greater in patients than in controls (p< 0.05). RA was not significantly different between patients and controls (p> 0.05); however, a significant positive correlation was found between serum RA and both IL-10 and TGF-β in AR patients.

Conclusion

Our data suggest that RA may influence AR risk via affecting the TGF-β and IL-10 production.

Effect of Low-Immunogenic Yogurt Drinks and Probiotic Bacteria on Immunoreactivity of Cow's Milk Proteins and Tolerance Induction-In Vitro and In Vivo Studies

There is no effective therapy for milk allergy. The role of lactic acid bacteria (LAB) and probiotics in protection against allergy-related outcomes is still under investigation. The aim of the study was to evaluate the immunomodulative and therapeutic potential of yogurt drinks in cow's milk allergy (CMA) management. We compared immunoreactivity of α-casein (α-CN), β-casein (β-CN), κ-casein (κ-CN), α-lactalbumin (α-LA), and β-lactoglobulin (β-LG) in 27 yogurt drinks fermented with different basic yogurt cultures, or yogurt cultures enriched with Lactobacillus plantarum and/or Bifidobacterium lactis strains, by competitive ELISA assay. Drinks with the lowest antigenic potential were used as allergoids for CMA therapy. BALB/c mice were sensitized via intraperitoneal injection of α-CN + β-LG mixture with aluminum adjuvant, and gavaged with increasing doses of selected low-immunogenic drinks (YM-basic, or YM-LB-enriched with L. plantarum and B. lactis) to induce tolerance. Milk- or phosphate-buffered saline (PBS)-dosed mice served as controls. Compared to milk, the immunoreactivity of proteins in drinks increased or decreased, depending on the bacterial sets applied for fermentation. Only a few sets acted synergistically in reducing immunoreactivity. The selected low-immunogenic drinks stimulated allergic mice for profiling Th2 to Th1 response and acquire tolerance, and the effect was greater with YM-LB drink, which during long-lasting interventional feeding strongly increased the secretion of regulatory cytokines, i.e., IL-10 and TGF-β, and IgA and decreased IL-4, IgE, and anti-(α-CN + β-LG) IgG1. The studies revealed variations in the potency of yogurt bacteria to change allergenicity of milk proteins and the need for their strict selection to obtain a safe product for allergy sufferers. The YM-LB drink with reduced antigenic potential may be a source of allergoids used in the immunotherapy of IgE mediated CMA, but further clinical or volunteer studies are required.

Production of hypoallergenic milk from DNA-free beta-lactoglobulin (BLG) gene knockout cow using zinc-finger nucleases mRNA

The whey protein β-lactoglobulin (BLG) is a major milk allergen which is absent in human milk. Here, we for the first time generated DNA-free BLG bi-allelic knockout cow by zinc-finger nuclease (ZFNs) mRNA and produced BLG-free milk. According to the allergenicity evaluation of BLG-free milk, we found it can trigger lower allergic reaction of Balb/c mice including the rectal temperature drop and the allergen-specific immunoglobulin IgE production; BLG free-milk was easily digested by pepsin at 2 min, while BLG in control milk was still not completely digested after 60 min, and the binding of IgE from cow's milk allergy (CMA) patients to BLG free-milk was significantly lower than that to the control milk. Meanwhile, the genome sequencing revealed that our animal is free of off-target events. Importantly, editing animal genomes without introducing foreign DNA into cells may alleviate regulatory concerns related to foods produced by genome edited animals. Finally, the ZFNs-mediated targeting in cow could be transmitted through the germline by breeding. These findings will open up unlimited possibilities of modifying milk composition to make it more suitable for human health and also improve the functional properties of milk.

Immune mechanisms of food allergy and its prevention by early intervention

The environmental factors driving the increase in food allergies are unclear and possibly involve dual exposure to allergens, microbiome-driven effects or other mechanisms. Until they can be better understood, early intervention aiming at establishing oral tolerance provides an effective way to decrease the window-of-risk when children may develop allergic sensitisation to foods due to the absence of a protective immune response. Thus, the recent LEAP (Learning Early About Peanut allergy) and LEAP-On studies achieved a high level of peanut allergy prevention by early introduction of peanuts in the infants diet and conveyed more information regarding the evolution of IgE and IgG4 antibody responses to food antigens over time.

Anti-allergic activity of glycyrrhizic acid on IgE-mediated allergic reaction by regulation of allergy-related immune cells

Glycyrrhizic acid (GA), the major bioactive triterpene glycoside of glycyrrhiza, has been shown to possess a wide range of pharmacological properties, including anti-inflammatory and anti-viral properties. However, few studies have examined the anti-allergic activity and exact mechanism of action of GA. In the present work, the anti-allergic activity and possible mechanisms of action of GA on an immunoglobulin (Ig) E-mediated allergic reaction has been studied using three models of allergic reaction in vivo and in vitro. Active systemic allergic reaction in Balb/c mice showed that GA can suppress the increased level of IL-4 to restore the immune balance of TH1/TH2 cells in a dose-dependent manner. Additionally, GA attenuated significantly the B cells producing allergen-specific IgE and IgG1 partly because of the low levels of TH2 cytokines. Both passive cutaneous anaphylaxis in vivo and an RBL-2H3 cell-based immunological assay in vitro indicated that GA acted as a "mast cell stabilizer", as it inhibited mast cell degranulation and decreased vascular permeability by inhibiting the expression of Orai1, STIM1 and TRPC1, which blocked extracellular Ca2+ influxes. The current study suggests that GA may serve as an effective anti-allergic agent derived from food for the prevention and treatment of IgE-mediated allergic reaction.

How Proteins Aggregate Can Reduce Allergenicity: Comparison of Ovalbumins Heated under Opposite Electrostatic Conditions

Heated foods are recommended for avoiding sensitization to food proteins, but depending on the physicochemical conditions during heating, more or less unfolded proteins aggregate differently. Whether the aggregation process could modulate allergenicity was investigated. Heating ovalbumin in opposite electrostatic conditions led to small (A-s, about 50 nm) and large (A-L, about 65 μm) aggregates that were used to sensitize mice. The symptoms upon oral challenge and rat basophil leukemia degranulation with native ovalbumin differed on the basis of which aggregates were used during the sensitization. Immunoglobulin-E (IgE) production was significantly lower with A-s than with A-L. Although two common linear IgE-epitopes were found, the aggregates bound and cross-linked IgE similarly or differently, depending on the sensitizing aggregate. The ovalbumin aggregates thus displayed a lower allergenic potential when formed under repulsive rather than nonrepulsive electrostatic conditions. This further demonstrates that food structure modulates the immune response during the sensitization phase with some effects on the elicitation phase of an allergic reaction and argues for the need to characterize the aggregation state of allergens.

A Specific Mixture of Fructo-Oligosaccharides and Bifidobacterium breve M-16V Facilitates Partial Non-Responsiveness to Whey Protein in Mice Orally Exposed to β-Lactoglobulin-Derived Peptides

Oral tolerance is a promising approach for allergy prevention in early life, but it strongly depends on allergen exposure and proper immune environment. Small tolerance-inducing peptides and dietary immunomodulatory components may comprise an attractive method for allergy prevention in at-risk infants. This study aimed to investigate whether early oral exposure to β-lactoglobulin-derived peptides (BLG-peptides) and a specific synbiotic mixture of short- and long- chain fructo-oligosaccharides (scFOS/lcFOS, FF) and Bifidobacterium breve (Bb) M-16V (FF/Bb) can prevent cow’s milk allergy (CMA). Three-week-old female C3H/HeOuJ mice were orally exposed to phosphate buffered saline (PBS), whey protein, or a mixture of four synthetic BLG-peptides combined with a FF/Bb-enriched diet prior to intragastric sensitization with whey protein and cholera toxin. To assess the acute allergic skin response and clinical signs of allergy, mice were challenged intradermally with whole whey protein. Serum immunoglobulins were analyzed after a whey protein oral challenge. Cytokine production by allergen-reactivated splenocytes was measured and changes in T cells subsets in the spleen, mesenteric lymph nodes, and intestinal lamina propria were investigated. Pre-exposing mice to a low dosage of BLG-peptides and a FF/Bb-enriched diet prior to whey protein sensitization resulted in a significant reduction of the acute allergic skin response to whey compared to PBS-pretreated mice fed a control diet. Serum immunoglobulins were not affected, but anaphylactic symptom scores remained low and splenocytes were non-responsive in whey-induced cytokine production. In addition, preservation of the T_h1/T_h2 balance in the small intestine lamina propria was a hallmark of the mechanism underlying the protective effect of the BLG-peptides–FF/Bb intervention. Prior exposure to BLG-peptides and a FF/Bb-enriched diet is a promising approach for protecting the intestinal T_h1/T_h2 balance and reducing the allergic response to whole whey protein. Therefore, it might have implications for developing successful nutritional strategies for CMA prevention.

Antibody Production, Anaphylactic Signs, and T-Cell Responses Induced by Oral Sensitization With Ovalbumin in BALB/c and C3H/HeOuJ Mice

Purpose

Two mouse strains, BALB/c and C3H/HeOuJ, broadly used in the field of food allergy, were compared for the evaluation of the allergenic potential of ovalbumin (OVA).

Methods

Sensitization was made by administering 2 different OVA doses (1 and 5 mg), with cholera toxin as Th2-polarizing adjuvant. Antibody levels, severity of anaphylaxis, and Th1 and Th2 responses induced by the allergen were assessed. In addition, because the mice selected had functional toll-like receptor 4, the influence of contamination with lipopolysaccharide (LPS) on the immunostimulating capacity of OVA on spleen cells was also evaluated.

Results

Both strains exhibited similar susceptibility to OVA sensitization. The 2 protein doses generated similar OVA-specific IgE and IgG1 levels in both strains, whereas C3H/HeOuJ mice produced significantly more IgG2a. Oral challenge provoked more severe manifestations in C3H/HeOuJ mice as indicated by the drop in body temperature and the severity of the anaphylactic scores. Stimulation of splenocytes with OVA led to significantly higher levels of Th2 and Th1 cytokines in BALB/c, and these were less affected by protein contamination with LPS.

Conclusions

The antibody and cytokine levels induced by OVA in BALB/c mice and the observation that BALB/c spleen cell cultures were more resistant than those of C3H/HeOuJ mice to the stimulus of LPS make this strain prone to exhibit Th2-mediated food allergic reactions and very adequate for the study of the features of OVA that make it allergenic.

Distinct transcriptome profiles differentiate nonsteroidal anti-inflammatory drug-dependent from nonsteroidal anti-inflammatory drug-independent food-induced anaphylaxis

BACKGROUND

Lipid transfer protein (LTP), an abundant protein in fruits, vegetables, and nuts, is a common food allergen in Mediterranean areas causing diverse allergic reactions. Approximately 40% of food-related anaphylaxis induced by LTPs requires nonsteroidal anti-inflammatory drugs (NSAIDs) as a triggering cofactor.

OBJECTIVE

We sought to better understand the determinants of NSAID-dependent and NSAID-independent LTP-induced anaphylaxis (LTP-A).

METHODS

Selection of patients was based on a proved clinical history of NSAID-dependent or NSAID-independent anaphylaxis to LTPs, positive skin prick test response to LTPs, and serum LTP IgE. Whole-transcriptome (RNA sequencing) analysis of blood cells from 14 patients with NSAID-related LTP-A (NSAID-LTP-A), 7 patients with LTP-A, and 13 healthy control subjects was performed to identify distinct gene expression signatures.

RESULTS

Expression of genes regulating gastrointestinal epithelial renewal was altered in both patient sets, particularly in those with LTP-A, who also presented with gene expression profiles characteristic of an inflammatory syndrome. These included altered B-cell pathways, increased neutrophil activation markers, and increased reactive oxygen species levels. Increased expression of the IgG receptor (CD64) in patients with LTP-A was mirrored by the presence of LTP-specific IgG1 and IgG3. Conversely, patients with NSAID-LTP-A were characterized by reduced expression of IFN-γ-regulated genes and IFN-γ levels, as well as upregulated expression of adenosine receptor 3 (ADORA3) and genes related to adenosine metabolism.

CONCLUSIONS

Gene ontology analysis suggests disturbances in gut epithelial homeostasis in both groups with LTP-A, with potential integrity breaches in patients with LTP-A that might explain their distinct inflammatory signatures. Differential regulation in patients with LTP-A and those with NSAID-LTP-A of the IFN-γ pathway, IgG receptors, and ADORA3 might provide the pathogenic basis of their distinct responses.

Food allergy enhances allergic asthma in mice

Background

Atopic march refers to the typical transition from a food allergy in early childhood to allergic asthma in older children and adults. However the precise interplay of events involving gut, skin and pulmonary inflammation in this process is not completely understood.

Objectives

To develop a mouse model of mixed food and respiratory allergy mimicking the atopic march and better understand the impact of food allergies on asthma.

Methods

Food allergy to ovalbumin (OVA) was induced through intra-peritoneal sensitization and intra-gastric challenge, and/or a respiratory allergy to house dust mite (HDM) was obtained through percutaneous sensitization and intra-nasal challenges with dermatophagoides farinae (Der f) extract. Digestive, respiratory and systemic parameters were analyzed.

Results

OVA-mediated gut allergy was associated with an increase in jejunum permeability, and a worsening of Der f-induced asthma with stronger airway hyperresponsiveness and pulmonary cell infiltration, notably eosinophils. There was overproduction of the pro-eosinophil chemokine RANTES in broncho-alveolar lavages associated with an enhanced Th2 cytokine secretion and increased total and Der f-specific IgE when the two allergies were present. Both AHR and lung inflammation increased after a second pulmonary challenge.

Conclusion

Gut sensitization to OVA amplifies Der f-induced asthma in mice.

Multi-faceted functions of secretory IgA at mucosal surfaces

Secretory IgA (SIgA) plays an important role in the protection and homeostatic regulation of intestinal, respiratory, and urogenital mucosal epithelia separating the outside environment from the inside of the body. This primary function of SIgA is referred to as immune exclusion, a process that limits the access of numerous microorganisms and mucosal antigens to these thin and vulnerable mucosal barriers. SIgA has been shown to be involved in avoiding opportunistic pathogens to enter and disseminate in the systemic compartment, as well as tightly controlling the necessary symbiotic relationship existing between commensals and the host. Clearance by peristalsis appears thus as one of the numerous mechanisms whereby SIgA fulfills its function at mucosal surfaces. Sampling of antigen-SIgA complexes by microfold (M) cells, intimate contact occurring with Peyer’s patch dendritic cells (DC), down-regulation of inflammatory processes, modulation of epithelial, and DC responsiveness are some of the recently identified processes to which the contribution of SIgA has been underscored. This review aims at presenting, with emphasis at the biochemical level, how the molecular complexity of SIgA can serve these multiple and non-redundant modes of action.

Epicutaneous sensitization results in IgE-dependent intestinal mast cell expansion and food-induced anaphylaxis

BACKGROUND

Sensitization to food antigen can occur through cutaneous exposure.

OBJECTIVE

We sought to test the hypothesis that epicutaneous sensitization with food antigen predisposes to IgE-mediated anaphylaxis on oral allergen challenge.

METHODS

BALB/c mice were epicutaneously sensitized by repeated application of ovalbumin (OVA) to tape-stripped skin over 7 weeks or orally immunized with OVA and cholera toxin (CT) weekly for 8 weeks and then orally challenged with OVA. Body temperature was monitored, and serum mouse mast cell protease 1 levels were determined after challenge. Tissue mast cell (MC) counts were examined by using chloroacetate esterase staining. Levels of serum OVA-specific IgE and IgG(1) antibodies and cytokines in supernatants of OVA-stimulated splenocytes were measured by means of ELISA. Serum IL-4 levels were measured by using an in vivo cytokine capture assay.

RESULTS

Epicutaneously sensitized mice exhibited expansion of connective tissue MCs in the jejunum, increased serum IL-4 levels, and systemic anaphylaxis after oral challenge, as evidenced by decreased body temperature and increased serum mouse mast cell protease 1 levels. Intestinal MC expansion and anaphylaxis were IgE dependent because they did not occur in epicutaneously sensitized IgE(-/-) mice. Mice orally immunized with OVA plus CT did not have increased serum IL-4 levels, expanded intestinal MCs, or anaphylaxis after oral challenge, despite OVA-specific IgE levels and splenocyte cytokine production in response to OVA stimulation, which were comparable with those of epicutaneously sensitized mice.

CONCLUSION

Epicutaneously sensitized mice, but not mice orally immunized with antigen plus CT, have expansion of intestinal MCs and IgE-mediated anaphylaxis after single oral antigen challenge. IgE is necessary but not sufficient for food anaphylaxis, and MC expansion in the gut can play an important role in the development of anaphylaxis.

Pretreatment with glycomacropeptide reduces allergen sensitization, alleviates immediate cutaneous hypersensitivity and protects from anaphylaxis

Allergic disorders are characterized by the involvement of allergen-specific immunoglobulin (Ig)E antibodies and T helper type 2 (Th2) cells. The search for new therapies for allergic diseases has been the primary focus of interest for many investigators in recent years. Glycomacropeptide (GMP) is a biologically active component of milk that exhibits a range of immunomodulatory functions. We examined whether oral administration of GMP could affect the development of allergic sensitization and the severity of immediate cutaneous hypersensitivity reactions and of anaphylaxis. Rats treated with or without GMP were ovalbumin (OVA)-sensitized and several indicators of allergy were evaluated. Pretreatment with GMP resulted in reduction of antigen-specific IgE titre in rats when sensitized with OVA. GMP administration also markedly suppressed the proliferative response of splenocytes to antigen and the production of interleukin (IL)-13 by splenocytes of sensitized animals. In addition, GMP pretreatment attenuated the intensity of the immediate cutaneous reaction induced by antigen and protected the sensitized rats from severe anaphylaxis. These data demonstrate, for the first time, that the administration of GMP prevents allergen sensitization and reduces the severity of the early-phase reaction induced by antigen in cutaneous hypersensitivity and in anaphylaxis. GMP may be used as a novel prophylactic agent for the control of allergic diseases.

Nigella sativa (black cumin) seed extract alleviates symptoms of allergic diarrhea in mice, involving opioid receptors

The incidence of food hypersensitivity and food allergies is on the rise and new treatment approaches are needed. We investigated whether N. sativa, one of its components, thymoquinone, or synthetic opioid receptor (OR)-agonists can alleviate food allergy. Hence, ovalbumin (OVA)-sensitized BALB/c-mice were pre-treated either with a hexanic N. sativa seed extract, thymoquinone, kappa-(U50'4889) or mu-OR-agonists (DAMGO) and subsequently challenged intra-gastrically with OVA. All 4 treatments significantly decreased clinical scores of OVA-induced diarrhea. N. sativa seed extract, thymoquinone, and U50'488 also decreased intestinal mast cell numbers and plasma mouse mast cell protease-1 (MMCP-1). DAMGO, in contrast, had no effect on mast cell parameters but decreased IFNγ, IL-4, IL-5, and IL-10 concentration after ex vivo re-stimulation of mesenteric lymphocytes. The effects on allergy symptoms were reversible by OR-antagonist pre-treatment, whereas most of the effects on immunological parameter were not. We demonstrate that N. sativa seed extract significantly improves symptoms and immune parameters in murine OVA-induced allergic diarrhea; this effect is at least partially mediated by thymoquinone. ORs may also be involved and could be a new target for intestinal allergy symptom alleviation. N. sativa seed extract seems to be a promising candidate for nutritional interventions in humans with food allergy.

Heat-induced structural changes affect OVA-antigen processing and reduce allergic response in mouse model of food allergy

Background and Aims

The egg protein ovalbumin (OVA) belongs to six most frequent food allergens. We investigated how thermal processing influences its ability to induce allergic symptoms and immune responses in mouse model of food allergy.

Methodology/Principal Findings

Effect of increased temperature (70°C and 95°C) on OVA secondary structure was characterized by circular dichroism and by the kinetics of pepsin digestion with subsequent HPLC. BALB/c mice were sensitized intraperitoneally and challenged with repeated gavages of OVA or OVA heated to 70°C (h-OVA). Levels of allergen-specific serum antibodies were determined by ELISA (IgA and IgGs) or by β-hexosaminidase release test (IgE). Specific activities of digestive enzymes were determined in brush border membrane vesicles of jejunal enterocytes. Cytokine production and changes in regulatory T cells in mesenteric lymph nodes and spleen were assessed by ELISA and FACS. Heating of OVA to 70°C caused mild irreversible changes in secondary structure compared to boiling to 95°C (b-OVA), but both OVA treatments led to markedly different digestion kinetics and Tregs induction ability in vitro, compared to native OVA. Heating of OVA significantly decreased clinical symptoms (allergic diarrhea) and immune allergic response on the level of IgE, IL-4, IL-5, IL-13. Furthermore, h-OVA induced lower activities of serum mast cell protease-1 and enterocyte brush border membrane alkaline phosphatase as compared to native OVA. On the other hand h-OVA stimulated higher IgG2a in sera and IFN-γ secretion by splenocytes.

Conclusions

Minor irreversible changes in OVA secondary structure caused by thermal processing changes both its digestion and antigenic epitopes formation, which leads to activation of different T cell subpopulations, induces shift towards Th1 response and ultimately reduces its allergenicity.

Secretory IgA's complex roles in immunity and mucosal homeostasis in the gut

Secretory IgA (SIgA) serves as the first line of defense in protecting the intestinal epithelium from enteric toxins and pathogenic microorganisms. Through a process known as immune exclusion, SIgA promotes the clearance of antigens and pathogenic microorganisms from the intestinal lumen by blocking their access to epithelial receptors, entrapping them in mucus, and facilitating their removal by peristaltic and mucociliary activities. In addition, SIgA functions in mucosal immunity and intestinal homeostasis through mechanisms that have only recently been revealed. In just the past several years, SIgA has been identified as having the capacity to directly quench bacterial virulence factors, influence composition of the intestinal microbiota by Fab-dependent and Fab-independent mechanisms, promote retro-transport of antigens across the intestinal epithelium to dendritic cell subsets in gut-associated lymphoid tissue, and, finally, to downregulate proinflammatory responses normally associated with the uptake of highly pathogenic bacteria and potentially allergenic antigens. This review summarizes the intrinsic biological activities now associated with SIgA and their relationships with immunity and intestinal homeostasis.

Lactococcus lactis NCC 2287 alleviates food allergic manifestations in sensitized mice by reducing IL-13 expression specifically in the ileum

Objective. Utilizing a food allergy murine model, we have investigated the intrinsic antiallergic potential of the Lactococcus lactis NCC 2287 strain. Methods. BALB/c mice were sensitized at weekly intervals with ovalbumin (OVA) plus cholera toxin (CT) by the oral route for 7 weeks. In this model, an oral challenge with a high dose of OVA at the end of the sensitization period leads to clinical symptoms. Lactococcus lactis NCC 2287 was given to mice via the drinking water during sensitization (prevention phase) or after sensitization (management phase). Results. Lactococcus lactis NCC 2287 administration to sensitized mice strikingly reduced allergic manifestations in the management phase upon challenge, when compared to control mice. No preventive effect was observed with the strain. Lactococcus lactis NCC 2287 significantly decreased relative expression levels of the Th-2 cytokine, IL-13, and associated chemokines CCL11 (eotaxin-1) and CCL17 (TARC) in the ileum. No effect was observed in the jejunum. Conclusion/Significance. These results taken together designate Lactococcus lactis NCC 2287 as a candidate probiotic strain appropriate in the management of allergic symptoms.

Epicutaneous challenge of orally immunized mice redirects antigen-specific gut-homing T cells to the skin

Patients with atopic dermatitis (AD) often suffer from food allergy and develop flares upon skin contact with food allergens. However, it is unclear whether T cells sensitized to allergens in the gut promote this skin inflammation. To address this question, we orally immunized WT mice and mice lacking the skin-homing chemokine receptor Ccr4 (Ccr4-/- mice) with OVA and then challenged them epicutaneously with antigen. Allergic skin inflammation developed in the WT mice but not in the mutants and was characterized by epidermal thickening, dermal infiltration by eosinophils and CD4+ T cells, and upregulation of Th2 cytokines. T cells purified from mesenteric lymph nodes (MLNs) of orally immunized WT mice transferred allergic skin inflammation to naive recipients cutaneously challenged with antigen, but this effect was lost in T cells purified from Ccr4-/- mice. In addition, the ability of adoptively transferred OVA-activated T cells to home to the skin following cutaneous OVA challenge was ablated in mice that lacked lymph nodes. These results indicate that cutaneous exposure to food antigens can reprogram gut-homing effector T cells in LNs to express skin-homing receptors, eliciting skin lesions upon food allergen contact in orally sensitized AD patients.

Increased susceptibility of 129SvEvBrd mice to IgE-Mast cell mediated anaphylaxis

Background

Experimental analyses have identified strain-dependent factors that regulate susceptibility to anaphylaxis in mice. We assessed the susceptibility of the widely used 129SvEvBrd (also known as 129S5) mouse strain to IgE/mast cell-mediated anaphylaxis as compared to BALB/c. Mice were subjected to passive and oral Ovalbumin [OVA]-induced active anaphylaxis. Tissue mast cell, plasma histamine, total IgE and OVA-specific IgE levels and susceptibility to histamine i.v infusion were assessed. Bone marrow mast cell (BMMC)s were examined for Fc_εRI, c-kit, degranulation efficiency, proliferation, apoptosis and cytokine profile.

Results

129S5 mice had significantly increased susceptibility to passive and oral OVA-induced active anaphylaxis. Increased susceptibility to anaphylaxis was associated with increased homeostatic mast cell levels but not OVA-specific IgE or IgG₁ levels. In vitro analyses of BMMCs revealed no difference in Fc_εRI and c-Kit expression, however, 129S5 BMMCs possessed greater proliferative capacity and reduced caspase-3-mediated apoptosis. IgE-BMMC degranulation assays demonstrated no difference in degranulation efficiency. Furthermore, 129S5 mice possessed increased sensitivity to histamine-induced hypothermia.

Conclusions

We conclude that 129S5 mice have increased susceptibility to anaphylaxis as compared to BALB/c strain and their increased susceptibility was associated with altered mast cell proliferation and homeostatic tissue levels and responsiveness to histamine. Given the wide spread usage of the 129SvEvBrd strain of mice in experimental gene targeting methodology, these data have important implications for studying IgE-reactions in mouse systems.

Possible links between intestinal permeability and food processing: A potential therapeutic niche for glutamine

Increased intestinal permeability is a likely cause of various pathologies, such as allergies and metabolic or even cardiovascular disturbances. Intestinal permeability is found in many severe clinical situations and in common disorders such as irritable bowel syndrome. In these conditions, substances that are normally unable to cross the epithelial barrier gain access to the systemic circulation. To illustrate the potential harmfulness of leaky gut, we present an argument based on examples linked to protein or lipid glycation induced by modern food processing. Increased intestinal permeability should be largely improved by dietary addition of compounds, such as glutamine or curcumin, which both have the mechanistic potential to inhibit the inflammation and oxidative stress linked to tight junction opening. This brief review aims to increase physician awareness of this common, albeit largely unrecognized, pathology, which may be easily prevented or improved by means of simple nutritional changes.