Chronic oral antigen exposure induces lymphocyte migration in anaphylactic mouse intestine

Efficacy of an elimination diet in a patient with eosinophilic gastroenteritis : a pediatric case with multiple food allergies

Eosinophilic gastrointestinal disorders are chronic inflammatory diseases in which eosinophils highly infiltrate into gastrointestinal tissue, resulting in gastrointestinal dysfunction. Here, we report a case of pediatric eosinophilic gastroenteritis (EGE). A 7-year-old boy with multiple food allergies (cow milk, hen's egg, fish,shellfish, and chicken) was admitted to our hospital because of continuous abdominal pain and vomiting. His soy allergy had been diagnosed to have oral tolerance based on an oral food challenge at the age of 6 years. He was diagnosed with EGE based on biopsy findings showing eosinophilic infiltration ( 20 eosinophils per high-power field) into the gastrointestinal mucosa. A diet eliminating soy, wheat, beef, pork, rice, and sesame in addition to the food that had already been eliminated and oral corticosteroids improved his symptoms and peripheral eosinophilia. A relapse of both abdominal pain and peripheral eosinophilia after the reintroduction of soy or pork identified them as foods causative of EGE. This report highlights the utility of elimination diets in improving EGE symptoms and the subsequent reintroduction of offending foods in identifying causative foods. Furthermore,EGE onset should be considered when introducing potentially allergic food in the management of food allergy. J. Med. Invest. 66 : 201-204, February, 2019.

Food intolerance and mucosal inflammation

Most infants are immunologically active and are able to develop a tolerance to oligoclonal antigens by producing IgA, along with activation of regulatory T cells, in early infancy. Cytokines and their signaling molecules are important mediators in the intestine, regulating both oral tolerance and mucosal inflammation. This system works efficiently in most individuals, but for an as yet undefined reason, some people react to food and other proteins as though they were pathogens, with induction of chronic inflammation in the mucosa. The adverse reaction caused by ingested foods is defined as food intolerance. The clinical features of food intolerance include vomiting, diarrhea, bloody stool, eczema, failure to thrive, and a protean range of other symptoms. Intolerance can be divided into two categories depending on whether or not they are immunologically mediated. Food intolerance and mucosal inflammation are deeply related because tolerance cannot be established when there is an inflammation in the intestinal mucosa. Mast cells, eosinophils, mucosal lymphocytes, and epithelial cells are deeply involved and related to each other in the development of mucosal inflammation. Meanwhile, rectal bleeding in infancy is related to lymphoid hyperplasia with eosinophil infiltration into the colonic mucosa facilitated by C-C motif ligand 11 (CCL11, known as eotaxin-1) and C-X-C motif chemokine ligand 13 (CXCL13). Rectal bleeding in infancy may not be simply caused by allergic reactions against specific antigens, but may be due to migrated lymphocytes developing immunological tolerance; including IgA synthesizing, in the intestinal mucosa.

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

Few models have described a chronic food allergy with morphological changes in the intestinal mucosa. Here we established an ovalbumin (OVA)-induced, cell-mediated, allergic rat model and examined lymphocyte migration in the gut. Brown Norway rats were intraperitoneally sensitized to OVA and then given 10 mg OVA/day by gastric intubation for 6 wk. Lymphocyte subsets and adhesion molecules were examined immunohistochemically, and the migration of T lymphocytes to microvessels of Peyer's patches and villus mucosa was observed by using an intravital microscope. Serum OVA-specific IgG and IgE levels were increased in animals repeatedly exposed to OVA. Significant villus atrophy and increased crypt depth was accompanied by increased infiltration of T lymphocytes in the small intestinal mucosa of the group given OVA. Expression of rat mast cell protease II and of mucosal addressin cell adhesion molecule-1 (MAdCAM-1) was also increased in these groups. The administration of anti-MAdCAM-1 antibody significantly attenuated the OVA-induced changes in the mucosal architecture and in CD4 T lymphocyte infiltration. Intravital observation demonstrated that in rats with a chronic allergy, T lymphocytes significantly accumulated in villus microvessels as well as in Peyer's patches via a MAdCAM-1-dependent process. Our model of chronic food allergy revealed that lymphocyte migration was increased with MAdCAM-1 upregulation.

Immunohistochemical study of intestinal eosinophils in inflammatory bowel disease

BACKGROUND

Eosinophil accumulation and activation are characteristic features of inflammation in allergic diseases and in host defense against parasites.

GOALS

To investigate the involvement of eosinophils in inflamed and noninflamed mucosa of patients with inflammatory bowel disease (IBD).

STUDY

Specimens of inflamed colonic mucosa from 15 patients with ulcerative colitis (UC) and inflamed and noninflamed colonic mucosa from 15 patients with Crohn's disease (CD) were submitted to histologic and immunohistochemical studies. Twelve patients with irritable bowel syndrome were studied as controls. Sirius red was used to label eosinophils in tissue. EG1, EG2, and anti-hIL-5 were used as primary antibodies in an indirect alkaline phosphatase-labeled immunostaining protocol. Both positive and negative lamina propria cells were assessed by a quantitative grading system and the results expressed as cell numbers per mm.

RESULTS

Increased proportions of eosinophils stained with Sirius red, EG1, EG2, and anti-hIL-5+ cells were found in the colon of patients with UC and in inflamed and noninflamed colon of CD patients as compared with controls. Crohn's disease patients showed increased proportions of EG1+ and EG2+ cells as compared with those with UC. Increased proportions of IL-5+ cells were detected in UC patients as compared with those with CD.

CONCLUSION

Quantitative eosinophil alterations and IL-5+ cells may indicate enhanced cellular activation with degranulation, which is implicated in the pathogenesis of IBD. Increase in IL-5+ cells may reflect a predominant local Th2 response in UC as compared with CD.

Eosinophilic gastroenteritis: a problem of the mucosal immune system?

The gastrointestinal immune system is a major component of the mucosal barrier, which provides an appropriate immunologic homeostasis between host and numerous foreign antigens, including microbial and dietary antigens. However, under certain pathological circumstances created by disturbance of the immunologic balance, allergic responses associated with the gastrointestinal tract can be triggered by abnormal immune responses against selected food protein antigens. Among the several types of immune competent cells, eosinophils are generally considered to play a central role for the development of allergic diseases in gastrointestinal tissue. Although most research has been focused on the molecular and cellular understanding of eosinophils in the peripheral tissues and lung, recent studies elucidate the unique trafficking and regulation mechanisms of eosinophils in the gastrointestinal tissues. In this review, we summarize current findings in the regulatory mechanism of gastrointestinal eosinophils. Furthermore, several unique murine models for eosinophilic gastroenteritis, which can be applied for the elucidation of underlying mechanisms of eosinophil-mediated gastrointestinal allergy, and the development of new mucosal immune therapy for the control of food allergy are reviewed.

The mucosal immune system: from specialized immune defense to inflammation and allergy

The mucosal immune system is a first line of defense against foreign antigens, including microbial and dietary antigens. Under normal circumstances, the mucosal immune system employs tightly regulated dynamic mucosal intra- and internets consisting of inductive and effector sites for the induction of an appropriate immunological homeostasis between the host and mucosal environments. The common mucosal immune system (CMIS), which interconnects between inductive (e.g. Peyer patch) and effector (e.g. intestinal lamina propria) tissues for the induction of the IgA response, is well characterized. Recent results provide strong evidence for the presence of a CMIS-independent IgA induction pathway. Two distinct subsets of mucosal IgA-committed B cells termed B-1 and B-2, are associated with CMIS-independence and CMIS-dependent cascades respectively. In some cases, the breakdown of this tightly regulated mucosal immune system leads to pathological responses to different gut environmental antigens. As a result, disorders such as inflammatory bowel disease (e.g. IBD) and allergic gastroenteropathy can be evoked in the gastrointestinal tissues. Recently, many studies have described possible molecular and cellular mechanisms for this dysfunction in the gastrointestinal tissues by using murine models with specific gene manipulation. In this review we summarize recent findings from our group concerning the CMIS-dependent and CMIS-independent IgA induction pathways and gastrointestinal diseases (IBD and intestinal allergic diseases). These observations may provide useful information for the development of new mucosal immune therapy.

The mechanism for the contraction induced by leukotriene C4 in guinea-pig taenia coli

The mechanism underlying the LTC(4)-induced contraction of guinea-pig taenia coli was determined using the simultaneous measurements of [Ca(2+)](i) and force in whole muscle preparations. Additional experiments were performed in receptor coupled permeabilized preparation. For comparison purposes, the contraction which was induced by a typical G-protein mediated agonist, carbachol was also characterized. LTC(4) induced a contraction in the guinea-pig taenia coli in a concentration-dependent manner. The maximal response was obtained at 100 nM and the EC(50) value was 5.4+/-1.9 nM. Both LTC(4) and carbachol induced increases in [Ca(2+)](i) and force. The maximum force induced by 100 nM LTC(4) was significantly smaller than that induced by 10 microM carbachol, although an increase in [Ca(2+)](i) produced by both agonists was similar. In the permeabilized preparations, carbachol, but not LTC(4), induced an additional force development at a fixed Ca(2+) concentration. LTC(4) induced no increase in [Ca(2+)](i) and force in the Ca(2+)-free solution, while carbachol induced transient increases in both [Ca(2+)](i) and force in a Ca(2+)-free solution. Both diltiazem and SK&F 96365 significantly inhibited the LTC(4)- and carbachol-induced increases in [Ca(2+)](i) and force in normal PSS. The inhibitory pattern of [Ca(2+)](i) by these drugs was also similar. We thus conclude that LTC(4) induces the contraction of the guinea-pig taenia coli mainly through Ca(2+) influx via both the diltiazem-sensitive and SK&F 96365-sensitive Ca(2+) channels, without affecting either the Ca(2+)-sensitivity or the intracellular Ca(2+) release. These results indicated that the mechanism underlying the LTC(4)-induced contraction differs greatly from that for conventional G-protein mediated agonists, such as carbachol.

Systemically derived large intestinal CD4(+) Th2 cells play a central role in STAT6-mediated allergic diarrhea

Systemically primed BALB/c mice developed severe diarrhea after repeated oral administration of ovalbumin (OVA). Histological analysis demonstrated that dramatic infiltration of eosinophils and mast cells occurred in the large intestine but not in the small intestine of mice with diarrhea. Interestingly, CD4(+) alphabeta T cells of the large intestine secreted IL-4 and IL-13 at high levels. Identically treated STAT6 gene-disrupted mice failed to develop OVA-induced diarrhea. Further, treatment of BALB/c mice with monoclonal anti-IL-4 antibody prevented the development of allergic diarrhea. An adoptive transfer study showed that systemically primed splenic CD4(+) T cells were preferentially recruited into the large intestine upon exposure to oral OVA. These results strongly suggest that systemically derived CD4(+) alphabeta T cells of the large intestine play a critical role in the onset of Th2-mediated intestinal allergic disorders via STAT6 signal transduction.

A critical role for eotaxin in experimental oral antigen-induced eosinophilic gastrointestinal allergy

Despite marked advances in the understanding of allergic responses, the mechanisms regulating gastrointestinal allergy are not very well understood. We have developed a model of antigen-induced eosinophil-associated gastrointestinal allergy and characterized the role of eotaxin and IL-5. Challenge of allergen-sensitized mice with oral allergen, in the form of enteric-coated beads, resulted in marked allergen-specific IgG(1) and IgE, Th(2)-type (IL-4 and IL-5) cytokine production, and eosinophil accumulation in the blood and small intestine. In the genetic absence of eotaxin, a chemokine constitutively expressed in the gastrointestinal tract, eosinophil recruitment into the small intestine was ablated, and these mice developed enhanced eosinophil accumulation in the blood compared with wild-type mice. Interestingly, in the absence of IL-5, allergen challenge promoted partial eosinophil accumulation into the small intestine and a decline in circulating eosinophil levels. Collectively, these results establish that the accumulation of gastrointestinal eosinophils is antigen induced, can occur independent of IL-5, and provides a molecular mechanism to explain the dichotomy between peripheral blood and tissue eosinophilia. Furthermore, eotaxin is identified as a critical regulator of antigen-induced eosinophilic inflammation in the gastrointestinal tract.