Chronic allergy to dietary ovalbumin induces lymphocyte migration to rat small intestinal mucosa that is inhibited by MAdCAM-1

Chronic application of alcohol-soluble gluten extract over undamaged skin causes clinical sensitization for life-threatening anaphylaxis via activation of systemic Th2 immune responses in mice

Introduction

Gluten allergy is a major public health problem that is growing at an alarming rate. Specific mechanisms underlying sensitization to gluten remain incompletely understood. Currently, it is unclear whether chronic exposure to alcohol-soluble gluten extract via undamaged skin has the capacity to clinically sensitize mice for life-threatening anaphylaxis. Using an adjuvant-free mouse model, here we tested the hypothesis that chronic application of alcohol-soluble durum gluten (ASDG) extract will clinically sensitize mice for life-threatening anaphylaxis.

Methods

This study was conducted in a gluten-free Balb/c mouse colony that was established and maintained on a plant protein-free diet. Groups of adult female mice were exposed dermally to ASDG extract or vehicle once a week for 9-weeks. Specific (s) and total (t) IgE levels were quantified. Mice were challenged systemically with ASDG to measure symptoms of systemic anaphylaxis. Hypothermic shock response (HSR) and mucosal mast cell degranulation response (MMCR) were determined upon challenge. Spleen Th1, Th2, and other immune markers were quantified.

Results

We found that chronic exposure to ASDG elicited robust elevation of sIgE and tIgE. Systemic challenge with ASDG, but not vehicle, elicited life-threatening anaphylaxis associated with dramatic HSR and MMCR. Correlation analysis demonstrated direct positive inter-relationships among IgE, HSR, and MMCR. Anaphylaxis was associated with significant elevation of prototypic Th2 but not Th1 immune markers in the spleen.

Discussion/Conclusion

Our study collectively demonstrates that ASDG is intrinsically allergenic; and chronic exposure to ASDG via undamaged skin can clinically sensitize mice for life-threatening anaphylaxis via activating the systemic Th2 immune responses.

Psychological Stress Exacerbates Inflammation of the Ileum via the Corticotropin-Releasing Hormone-Mast Cell Axis in a Mouse Model of Eosinophilic Enteritis

The effects of psychological stress on eosinophilic gastrointestinal disorders have not been elucidated. This study investigated the effects of psychological stress in a mouse model of eosinophilic enteritis (EoN). BALB/c mice were treated with ovalbumin (OVA) to create an EoN model and subjected to either water avoidance stress (WAS) or sham stress (SS). Microscopic inflammation, eosinophil and mast cell counts, mRNA expression, and protein levels of type 2 helper T cell (Th2) cytokines in the ileum were compared between groups. We evaluated ex vivo intestinal permeability using an Ussing chamber. A corticotropin-releasing hormone type 1 receptor (CRH-R1) antagonist was administered before WAS, and its effects were analyzed. WAS significantly increased diarrhea occurrence and, eosinophil and mast cell counts, and decreased the villus/crypt ratio compared to those in the SS group. The mRNA expression of CRH, interleukin IL-4, IL-5, IL-13, eotaxin-1, and mast cell tryptase β2 significantly increased, and the protein levels of IL-5, IL-13, and OVA-specific immunoglobulin E (IgE) also significantly increased in the WAS group. Moreover, WAS significantly increased the intestinal permeability. The CRH-R1 antagonist significantly inhibited all changes induced by WAS. Psychological stress exacerbated ileal inflammation via the CRH-mast cell axis in an EoN mouse model.

A study of the mechanisms responsible for the action of new immunosuppressants and their effects on rat small intestinal transplantation

In a series of studies, using an identical rat intestinal transplantation model, we evaluated the effects of several drugs. FK-506 caused a significant attenuation in the proliferation of allogeneic CD4+ T cells and IFN-γ secreting effector functions. FYT720 resulted in a marked reduction in the numbers of lymphocytes, associated with a reduction of T cell recruitment, in grafts. An anti-MAdCAM antibody was next reported to significantly down-regulate CD4+ T cell infiltration in intestinal grafts by blocking the adhesion molecule, and could be useful as an induction therapy. Concerning TAK-779, this CCR5 and CXCR3 antagonist diminished the number of graft-infiltrating cells by suppressing the expression of their receptors in the graft. As a result, it reduced the total number of recipient T cells involved in graft rejection. As the next step, we focused on the participation of monocytes/ macrophages in this field. PQA-18 has been the focus of a novel immunosuppressant that attenuates not only the production of various cytokines, such as IL-2 & TNF-α, on T cells, but the differentiation of macrophages by inhibiting PAK2 as well. In this report, we summarize our previous studies not only regarding the above drugs, but on an anti-complement drug and a JAK inhibitor as well.

Butterbur (Petasites hybridus) Extract Ameliorates Hepatic Damage Induced by Ovalbumin in Mice

The liver is the most vital organ that could be influenced by inducers of hypersensitivity such as ovalbumin. The current study was carried out to explore the effects of butterbur (Petasites hybridus) extract on the ovalbumin-induced liver hypersensitivity in Swiss albino male mice. Animals were divided into 4 groups, 1^st group served as a control group, 2^nd group treated with daily oral administration of 75 mg/kg of butterbur extract, 3^rd group received single oral dose 100 mg/kg of ovalbumin to induce hypersensitivity, and 4^th group treated with oral administration of butterbur extract one-day post to the hypersensitivity induction. Ovalbumin induces a significant increase in the activity of liver enzymes and MDA and decreased the activity of CAT after the ovalbumin treatment. Histopathological investigations revealed marked pathological alterations in liver tissues in the form of hyaline degeneration and fibrosis. Additionally, heavy immune response indicated by immunostaining of MDA and TNF-α could be observed. In contrast, posttreatment with butterbur extract after hypersensitivity induction resulted in a significant decrease of liver enzymes and oxidative stress and reduced the inflammation and fibrosis of liver tissues. These results suggest that butterbur extract is considered as anti-inflammatory and antioxidant therapeutic herb for hypersensitivity treatment of liver.

Hepatic Cytochrome P450 Activity and Nitric Oxide Production During Multiple Ovalbumin Challenges

BACKGROUND AND OBJECTIVES

Mast cell-mediated allergic diseases are a significant global health problem. Nitric oxide (NO) produced by acute type 1 allergies greatly suppresses hepatic cytochrome P450 (CYP) metabolism. A recent in vitro study demonstrated that repeated FcεRI-mediated activation intrinsically modulates mast cell function. We investigated the effect of ovalbumin (OVA) challenges on CYP activity and NO production under real immune responses.

METHODS

After repeated sensitization with OVA once a week, serum nitrate plus nitrite (NOx) and total plasma immunoglobulin E concentrations were measured using commercially available kits. Hepatic microsomal CYP-specific activities and protein expression were determined using typical substrates and by western blot, respectively. In the liver, the levels of inducible NO synthase (iNOS), F4/80, and c-kit mRNA were determined by real-time polymerase chain reaction. Hepatic total NOS activity was measured using a colorimetric assay kit.

RESULTS

When mice received multiple OVA challenges, the 11th sensitization elevated NOx concentrations in serum and suppressed the activities of five major CYPs without altering protein expression levels. After the 7th, 11th, and 15th sensitizations, F4/80-positive Kupffer cell and hepatic c-kit-dependent mast cell mRNA levels were similar to those of the control. The 7th and 11th sensitizations increased hepatic iNOS mRNA expression to 15-fold and threefold above control levels, respectively, but did not enhance the total NOS activity in the liver.

CONCLUSIONS

Multiple OVA challenges, unlike acute sensitization, greatly reduced serum NOx levels. The challenge-suppressed hepatic CYP metabolism was likely related to the increased serum NOx. Serum NOx may be an endogenous marker for CYP metabolism inhibition in type 1 allergic diseases.

Feeding probiotic Lactobacillus rhamnosus (MTCC 5897) fermented milk to suckling mothers alleviates ovalbumin-induced allergic sensitisation in mice offspring

The neonatal period is often polarised to T helper (Th2) response at the time of birth, predisposing offspring to allergic disorders. Passive immunity through the mother's milk is critical for immune system development of newborns. Probiotics have been proposed to harmonise Th1/Th2 imbalance in allergic conditions in adults. In the present study, the anti-allergic effects of feeding probiotic Lactobacillus rhamnosus-fermented milk (PFM) either to dams during the suckling period or to their offspring after weaning individually or else in successive periods against ovalbumin (OVA)-induced allergy in newborns was analysed. After allergen sensitisation, physical symptoms of allergy, gut immune response, humoral immune response and cell-mediated response through interleukins were detected. Consumption of PFM by mothers and offspring showed a reduction (P<0·01) in physical allergic symptoms in newborns with an increase (P<0·01) in the numbers of goblet and IgA+ cells in the small intestine. Similarly, considerable (P<0·001) decreases in OVA-specific antibodies (IgE, IgG, IgG1) and ratios of IgE/IgG2a and IgG1/IgG2a in the sera of newborn mice were recorded. A decrease in IL-4 and an increase in interferon-γ levels further confirmed the shift from Th2 to Th1 pathway in PFM-fed mice. It is logical to conclude that the timing of PFM intervention in alleviating allergic symptoms is critical, which was found to be most effective when mothers were fed during the suckling period.

Development and characterization of an effective food allergy model in Brown Norway rats

BACKGROUND

Food allergy (FA) is an adverse health effect produced by the exposure to a given food. Currently, there is no optimal animal model of FA for the screening of immunotherapies or for testing the allergenicity of new foods.

OBJECTIVE

The aim of the present study was to develop an effective and rapid model of FA in Brown Norway rats. In order to establish biomarkers of FA in rat, we compared the immune response and the anaphylactic shock obtained in this model with those achieved with only intraperitoneal immunization.

METHODS

Rats received an intraperitoneal injection of ovalbumin (OVA) with alum and toxin from Bordetella pertussis, and 14 days later, OVA by oral route daily for three weeks (FA group). A group of rats receiving only the i.p. injection (IP group) were also tested. Serum anti-OVA IgE, IgG1, IgG2a, IgG2b and IgA antibodies were quantified throughout the study. After an oral challenge, body temperature, intestinal permeability, motor activity, and mast cell protease II (RMCP-II) levels were determined. At the end of the study, anti-OVA intestinal IgA, spleen cytokine production, lymphocyte composition of Peyer's patches and mesenteric lymph nodes, and gene expression in the small intestine were quantified.

RESULTS

Serum OVA-specific IgG1, IgG2a and IgG2b concentrations rose with the i.p. immunization but were highly augmented after the oral OVA administration. Anti-OVA IgE increased twofold during the first week of oral OVA gavage. The anaphylaxis in both IP and FA groups decreased body temperature and motor activity, whereas intestinal permeability increased. Interestingly, the FA group showed a much higher RMCP II serum protein and intestinal mRNA expression.

CONCLUSIONS

These results show both an effective and relatively rapid model of FA assessed by means of specific antibody titres and the high production of RMCP-II and its intestinal gene expression.

Mucosal immunity in gut and lymphoid cell trafficking

Intestine has a well-developed lymphatic system that is closely related with its functions, such as mucosal immunological defense or absorption of nutrients. Intestinal lymphoid cells such as lymphocytes, macrophages/monocytes, or dendritic cells are continuously migrating through intestinal mucosa, thereby facilitating their immune responses. Their migrations are well controlled by well-organized molecular mechanisms including adhesion molecules, chemokines, etc. This manuscript will review how dysfunction of lymphoid cell migration is involved in intestinal inflammation, especially in the pathophysiology of intestinal bowel diseases. (*English Translation of J Jpn Coll Angiol 2008; 48: 143-149.).

Cytokine profile of rats fed a diet containing shrimp

OBJECTIVE: Studies have shown that shrimps reduced the tensile strength of scars in rat skin. The aim of the present study was to assess the cytokine profile of rats fed shrimp. METHODS: Group 1 (control) received a regular diet and Group 2 (experimental) received a diet containing 33% shrimp for nine days. The two diets contained the same amounts of proteins, fats and carbohydrates. Serum cytokine levels were determined by ELISA and a segment of the jejunum was taken to investigate its histological morphology and eosinophil infiltrate. RESULTS: The experimental group had lower serum levels of interleukin-4 (IL-4) (14.4±1.9 versus 18.11±2.6pg/mL; p<0.05) and IL-10 (5.0±0.98 versus 7.5±1.2pg/mL; p<0.05) and higher levels of IL-6 (17.8±2.3 versus 3.2±0.4pg/mL, p<0.001) than controls. Morphologically, the shrimp-based diet caused an architectural disorganization of the intestinal mucosa and a greater amount of eosinophils in the jejunal villus. CONCLUSION: Our data suggests that shrimp consumption leads to a significant increase in the cytokine IL-6, a decrease in the immunomodulatory cytokine IL-10 in the serum of rats, and high eosinophil infiltration in the jejunum. The cytokine profile typical of inflammation and the histological aspect of the jejunum are compatible with food allergy.

Anti-Siglec-F antibody inhibits oral egg allergen induced intestinal eosinophilic inflammation in a mouse model

Siglec-F is a sialic acid binding immunoglobulin-superfamily receptor that is highly expressed on eosinophils. We have used a mouse model of oral egg ovalbumin (OVA)-induced eosinophilic inflammation of the gastro-intestinal mucosa associated with diarrhea and weight loss to determine whether administering an anti-Siglec-F antibody would reduce levels of intestinal mucosal eosinophilic inflammation. Mice administered the anti-Siglec-F antibody had significantly lower levels of intestinal eosinophilic inflammation, and this was associated with reduced intestinal permeability changes, normalization of intestinal villous crypt height, and restoration of weight gain. The reduced numbers of intestinal eosinophils in anti-Siglec-F antibody treated mice was associated with significantly reduced numbers of bone marrow and peripheral blood eosinophils, but was not associated with significant changes in the numbers of proliferating or apoptotic jejunal eosinophils. In addition, the anti-Siglec-F Ab reduced Th2 cytokines and IgE levels. Overall, these studies demonstrate that administration of an anti-Siglec-F antibody significantly reduces levels of eosinophilic inflammation in the intestinal mucosa and that this was associated with reduced intestinal permeability changes, normalization of intestinal villous crypt height, and restoration of weight gain.

Alpha4beta7/MAdCAM-1 interactions play an essential role in transitioning cryptopatches into isolated lymphoid follicles and a nonessential role in cryptopatch formation

The alpha(4) integrins alpha(4)beta(7) and alpha(4)beta(1), and their ligands mucosal vascular addressin cell adhesion molecule 1 (MAdCAM-1) and VCAM-1, have diverse functions, including roles in the formation of secondary lymphoid tissues at early time points during the colonization and clustering of the fetal lymphoid tissue inducer (LTi) cells and at later time points during the recruitment of lymphocytes. In this study, we evaluated the role of alpha(4) integrins in the development of a recently appreciated class of intestinal lymphoid tissues, isolated lymphoid follicles (ILFs). We observed that diverse ILF cellular populations express alpha(4)beta(7) and alpha(4)beta(1), including the LTi-like cells and lymphocytes, while ILF stromal cells and vessels within ILFs express VCAM-1 and MAdCAM-1, respectively. Evaluation of adult and neonatal beta(7)(-/-) mice and adult and neonatal mice given blocking Abs to alpha(4)beta(7), MAdCAM-1, or VCAM-1 did not identify a role for alpha(4) integrins in cryptopatch (CP) development; however, these studies demonstrated that alpha(4)beta(7) and MAdCAM-1 are required for the transitioning of CP into lymphoid tissues containing lymphocytes or ILFs. Competitive bone marrow transfers demonstrated that beta(7)(-/-) LTi-like cells had a reduced but not significantly impaired ability to localize to CP. Bone marrow transfers and adoptive transfers of B lymphocytes revealed that beta(7) expression by B lymphocytes was essential for their entry into the developing ILFs. These findings demonstrate an essential role for alpha(4)beta(7)/MAdCAM-1 in ILF development corresponding to the influx of beta(7)-expressing lymphocytes and a nonessential role for beta(7)-localizing LTi-like cells to the small intestine.

Modulation of mucosal immunity in a murine model of food-induced intestinal inflammation

BACKGROUND

Hypersensitivity or uncontrolled responses against dietary antigens can lead to inflammatory disorders like food allergy and current models reflect a variety of causes but do not reveal the detailed modulation of gut immunity in response to food antigens after breakdown in mucosal tolerance.

OBJECTIVE

To develop and characterize a murine model for food-induced intestinal inflammation and to demonstrate the modulation of gut immune response by dietary allergenic antigens.

METHODS

C57BL/6 mice were sensitized with peanut proteins, challenged with peanut seeds and their sera and gut segments were collected for subsequent analyses.

RESULTS

Sensitization and challenged with peanut seeds led to alterations in gut architecture with inflammatory response characterized by oedema in lamina propria and cell infiltrate composed mainly by eosinophils, mast cells, phagocytes, natural killer and plasma cells, together with low percentage of gammadelta+ and CD4+CD25+Foxp3+ cells in Peyer's patches. These animals also presented high levels of specific IgE and IgG1 in sera and modulation of mucosal immunity was mediated by increased expression of GATA-3, IL-4, IL-13 and TNF-alpha in contrast to low IFN-gamma in the gut.

CONCLUSION

A murine model for food-induced intestinal inflammation was characterized in which modulation of gut immunity occurs by peanut antigens in consequence of T-helper type 2 (Th2) allergic response and failure of regulatory mechanisms necessary for mucosa homeostasis, resembling food allergy. This work shed some light on the understanding of the pathogenesis of gastrointestinal disorders and intolerance in the gut and supports the development of therapies for food-related enteropathies like food allergy, focusing on gut-specific immune response.

Effect of blocking the mucosal addressin cell adhesion molecule-1 (MAdCAM-1) in a rat small intestinal transplantation model

The effect of blocking the expression of the mucosal addressin cell adhesion molecule-1 (MAdCAM-1) in a graft by an antibody, and immunohistochemical changes in the graft were monitored, using a rat small intestinal transplantation model. Dark Agouti (DA) rat small intestines were heterotopically transplanted into Lewis (LEW) rats. The graft was treated with or without an anti-MAdCAM-1 antibody, F(ab')(2), during the operation. The survival of the grafts and histological changes, such as lymphocyte infiltration and destruction of the intestinal architecture in epithelium villus thickness, villus height and submucosal thickness of the graft, were examined. The expression of MAdCAM-1 and beta 7 integrin in the graft was also checked by immunostaining. Furthermore, graft infiltrating lymphocytes, in mesenteric lymph nodes (MLN) and Peyer's patches (PP) were measured by FACS analysis. Survival was prolonged in the DA graft with anti-MAdCAM-1 F(ab')(2) treatment; DA to LEW: 7.0+/-3.3, DA to LEW with the antibody: 24.6+/-8.4 days (p<0.05). Histological findings and scoring of the grafts were consistent with this conclusion. Moreover, MAdCAM-1 expression itself was suppressed in grafts of the antibody-treated group. While a FACS analysis showed no difference in the % of CD4+ T cells and CD8+ T cells in the PP of the graft, CD4+ T cells in the MLN of the antibody-treated graft were significantly low. A strategy directed at blocking the adhesion molecule, MAdCAM-1, in the small intestinal grafts could be useful in the prevention of acute rejection.

Murine model of food allergy after epicutaneous sensitization: role of mucosal mast cell protease-1

OBJECTIVE

Studies of the pathological mechanisms of food allergy have been impeded by the lack of relevant animal models. The purpose of this study was to develop a physiological model of food allergy that was not dependent on immunostimulatory adjuvants.

MATERIAL AND METHODS

Balb/c mice were epicutaneously sensitized four times at varying intervals over a 22-day period, and challenged orally from day 40, 6 times every 1-3 days with either saline or ovalbumin.

RESULTS

After sensitization (day 35) but before the oral challenges, the ovalbumin-sensitized groups showed increased specific IgE and IgG1 production when compared with the sham-sensitized groups. Mucosal mast cell protease-1 (MMCP-1) was undetectable in serum before the intragastric challenge. MMCP-1 concentrations were increased after the first ovalbumin dose, solely in the ovalbumin-sensitized and -challenged group. After the challenge period, the mean serum MMCP-1 concentration increased from an undetectable level in controls to an over 44-fold level in the ovalbumin-sensitized and -challenged mice. In this group, MMCP-1-positive cells were present in the small intestine and expressions of IFN-gamma and CXCL-9 mRNA were decreased in the ileum, suggesting an impaired Th-1-type response. Within one hour of the last ovalbumin challenge, 5 out of 6 mice developed diarrhea in the ovalbumin-sensitized and -challenged group, but there was no diarrhea in the other groups.

CONCLUSIONS

A murine model of food allergy based on sensitization via epicutaneous exposure to allergen without immunostimulatory adjuvants was developed. Effective production of MMCP-1 together with specific IgE and IgG1 suggests a breakdown in oral tolerance to the allergen. Intragastric challenges were accompanied by mast cell-dependent immunopathological changes and diarrhea.

Wheat-dependent exercise-induced anaphylaxis in mice is caused by gliadin and glutenin treatments

Various foods may be associated with food-dependent exercise-induced anaphylaxis (FDEIAn). However, although the most frequently reported cause of FDEIAn has been wheat, the mechanism of FDEIAn for wheat has remained largely uninvestigated. To investigate the effect of wheat-fractionated proteins on FDEIAn, female B10.A mice (16-20 g) were divided into four groups; i.e. salt-soluble (S-group), gliadin-rich (GLI-group), and glutenin-rich (GLU-group)-sensitized mice, and unsensitized mice. The three sensitized groups were run on a treadmill after oral intake of each wheat-fractionated protein. The mice showed a significant increase in serum IgE, especially in the GLI- and GLU-group. After oral administration of each wheat-fractionated protein, the running time until exhaustion was remarkably shorter for the GLI- and GLU-group than for the S-group and unsensitized mice. The level of intestinal erosion was higher in all the sensitized mice than that in the unsensitized ones after exhaustive running. Furthermore, moderate exercise for 30 min after oral ingestion of each wheat-fractionated protein also induced intestinal erosion in the GLI- and GLU-group. In addition, we observed leaking of gliadin and glutenin proteins out of the intestine into the liver. These results indicated that the main factor involved in wheat-dependent exercise-induced anaphylaxis might be the gliadin and glutenin in wheat proteins.