Mucosal allergy: role of mast cells and eosinophil granulocytes in the gut

Mucosal Eosinophil Abundance in Non-Inflamed Colonic Tissue Is Associated with Response to Vedolizumab Induction Therapy in Inflammatory Bowel Disease

Vedolizumab is used as a treatment for patients with inflammatory bowel disease (IBD), but induction therapy leads to clinical response and remission in approximately 55% and 30% of patients with IBD, respectively. In this study, we aimed to explore the predictive value of mucosal eosinophils and serum eotaxin-1 regarding response to vedolizumab induction therapy. Eighty-four (84) patients with IBD (37 Crohn’s disease [CD], 47 ulcerative colitis [UC]) were included. For 24 patients with IBD, histopathology was assessed for eosinophil counts in non-inflamed colonic tissue prior to vedolizumab treatment. For 64 patients with IBD, serum eotaxin-1 levels were quantified prior to (baseline) and during vedolizumab treatment. Serum samples of 100 patients with IBD (34 CD, 66 UC) from the GEMINI 1 and 2 trials were used for external validation. Baseline mucosal eosinophil numbers in non-inflamed colonic tissue were significantly higher in responders to vedolizumab induction therapy when compared to primary non-responders (69 [34−138] vs. 24 [18−28] eosinophils/high-power field, respectively, p < 0.01). Baseline serum eotaxin-1 levels in the discovery cohort were significantly elevated in responders, compared to primary non-responders (0.33 [0.23−0.44] vs. 0.20 [0.16−0.29] ng/mL, p < 0.01). Prediction models based on mucosal eosinophil counts and serum eotaxin-1 showed an area under the curve (AUC) of 0.90 and 0.79, respectively. However, the predictive capacity of baseline serum eotaxin-1 levels could not be validated in the GEMINI cohort. Mucosal eosinophil abundance in non-inflamed colonic tissue was associated with response to vedolizumab induction therapy in patients with IBD. Future studies are warranted to further validate the potential value of mucosal eosinophils and serum eotaxin-1 as biomarkers for response to vedolizumab therapy.

Reducing Pain in Experimental Models of Intestinal Inflammation Affects the Immune Response

The incidence of inflammatory bowel disease with its two main manifestations, colitis ulcerosa and Crohn's disease, is rising globally year after year. There is still a tremendous need to study the underlying pathomechanisms and a well-established tool in order to better understand the disease are colitis models in rodents. Since the concept of the 3Rs was proposed by Russell and Burch, this would include pain medication in animal models of intestinal inflammation as a reduction of suffering. This review argues against pain medication because the administration of pain medication in its current form has an impact on the inflammatory process and the immune response, thus falsifying the results and the reproducibility and therefore leading to misconceptions.

Duodenal mast cells and eosinophils in children with celiac disease: occurrence and distribution pattern

OBJECTIVE

The aim of this study was to characterize duodenal mast cell (MC) and eosinophil (EO) numbers, their distribution within the lamina propria and possible impact on disease severity of paediatric celiac patients compared to children without celiac disease (CD).

METHODS

We analysed duodenal samples of 215 children (109 CD, 106 controls) who underwent esophagogastroduodenoscopy from 2010 to 2018. After immunohistochemical staining, average MC and EO counts were histologically examined in ten high-power-fields. Additionally, cell-distribution within the lamina propria was analysed. Possible influence of relevant clinical parameters was evaluated.

STATISTICS

Student's-t-test, Mann-Whitney U-test, Chi-square-test, ANOVA, significance-level <.05. Trial registration-number: DRKS00024669.

RESULTS

MC-density was higher in CD-patients compared to the control-group (23.7 (±12.1)/HPF versus 19.7 (±9.1)/HPF; p = .008), varying in number interindividually. Eosinophils were also increased in the duodenum of celiac patients (23.3 (±9.3)/HPF versus 12.2 (±6.3)/HPF; p= <.001). MCs were distributed more often homogenously in all parts of CD lamina propria (44 biopsies (40.4%), residing more distant from the intestinal lumen in controls (0 biopsies with homogenous distribution-pattern (0%); p= <.001). Regarding EOs no polarity was observable. Atopic diseases did not occur significantly more often in patients with elevated EO-counts.

CONCLUSION

MC- and EO-numbers were increased in the duodenum of CD-patients and MCs showed a different distribution-pattern in the lamina propria of celiac patients. These findings support the concept that both cell-types contribute to disease-pathogenesis. However, functional studies highlighting both cell-types' and their mediators' role regarding mucosal alterations during the course of the inflammatory process in celiac patients are needed.

TRIAL REGISTRATION NUMBER AND URL

DRKS00024669; https://www.drks.de/drks_web/.

Dysregulation of intestinal epithelial CFTR-dependent Cl- ion transport and paracellular barrier function drives gastrointestinal symptoms of food-induced anaphylaxis in mice

Food-triggered anaphylaxis can encompass a variety of systemic and intestinal symptoms. Murine-based and clinical studies have revealed a role for histamine and H1R and H2R-pathway in the systemic response; however, the molecular processes that regulate the gastrointestinal (GI) response are not as well defined. In the present study, by utilizing an IgE-mast cell (MC)-dependent experimental model of oral antigen-induced anaphylaxis, we define the intestinal epithelial response during a food-induced anaphylactic reaction. We show that oral allergen-challenge stimulates a rapid dysregulation of intestinal epithelial transcellular and paracellular transport that was associated with the development of secretory diarrhea. Allergen-challenge induced (1) a rapid intestinal epithelial Cftr-dependent Cl- secretory response and (2) paracellular macromolecular leak that was associated with modification in epithelial intercellular junction proteins claudin-1, 2, 3 and 5, E-cadherin and desmosomal cadherins. OVA-induced Cftr-dependent Cl- secretion and junctional protein degradation was rapid occurring and was sustained for 72 h following allergen-challenge. Blockade of both the proteolytic activity and Cl- secretory response was required to alleviate intestinal symptoms of food-induced anaphylaxis. Collectively, these data suggest that the GI symptom of food-induced anaphylactic reaction, secretory diarrhea, is a consequence of CFTR-dependent Cl- secretion and proteolytic activity.

Mucosal Eosinophilia Is an Independent Predictor of Vedolizumab Efficacy in Inflammatory Bowel Diseases

BACKGROUND

Peripheral and mucosal eosinophilia may be associated with more aggressive disease in inflammatory bowel disease (IBD) patients. Vedolizumab blocks T lymphocytes, eosinophil adhesion, and extravasation in the gastrointestinal tract. It is not known if mucosal eosinophilia is a predictor for the therapeutic efficacy of vedolizumab.

METHODS

This was a retrospective cohort study of IBD patients with ileal or colonic biopsies who were off steroids before starting vedolizumab. Biopsies were rereviewed by pathologists, and mean eosinophil density was quantified. Patient characteristics and steroid-free clinical response 6 months after beginning vedolizumab were determined. Features were compared between nonresponders and responders, and multivariable logistic regression was performed to identify predictors of clinical response.

RESULTS

Of 251 IBD patients starting vedolizumab therapy, 65 patients (48% Crohn's disease, 52% ulcerative colitis) met inclusion criteria. All IBD patients not responding to vedolizumab were more likely to have a higher baseline mean eosinophil count (340 ± 156 vs 236 ± 124; P = 0.004), be previously exposed to an anti-TNF (96% vs 56%; P = 0.001), and be male (58% vs 28%; P = 0.02). Mean eosinophil counts were significantly increased in colonic biopsies in UC nonresponders (438 ± 149 vs 299 ± 145; P = 0.01). A similar trend was seen in CD nonresponders. On multivariable analysis, colonic eosinophil density and prior anti-TNF exposure-and the combination of both-were independent predictors of response.

CONCLUSION

In ulcerative colitis, colonic eosinophilia and prior anti-TNF exposure were independent predictors of 6-month clinical nonresponse to vedolizumab. Mucosal eosinophil density as a novel biomarker should be explored in larger patient cohorts.Aside from the previous anti-TNF exposure, eosinophil density in the colon of patients with UC is a negative predictor for a steroid-free long-term response to vedolizumab. The degree colonic eosinophilia may be a novel biomarker that should be further explored.

Intestinal overexpression of IL-18 promotes eosinophils-mediated allergic disorders

Baseline eosinophils reside in the gastrointestinal tract; however, in several allergic disorders, excessive eosinophils accumulate in the blood as well in the tissues. Recently, we showed in vitro that interleukin (IL)-18 matures and transforms IL-5-generated eosinophils into the pathogenic eosinophils that are detected in human allergic diseases. To examine the role of local induction of IL-18 in promoting eosinophil-associated intestinal disorders, we generated enterocyte IL-18-overexpressing mice using the rat intestinal fatty acid-binding promoter (Fabpi) and analysed tissue IL-18 overexpression and eosinophilia by performing real-time polymerase chain reaction, Enzyme-Linked Immunosorbent Assay and anti-major basic protein immunostaining. Herein we show that Fabpi-IL-18 mice display highly induced IL-18 mRNA and protein in the jejunum. IL-18 overexpression in enterocytes promotes marked increases of eosinophils in the blood and jejunum. Our analysis shows IL-18 overexpression in the jejunum induces a specific population of CD101⁺  CD274⁺ tissue eosinophils. Additionally, we observed comparable tissue eosinophilia in IL-13-deficient-Fabpi-IL-18 mice, and reduced numbers of tissue eosinophils in eotaxin-deficient-Fabpi-IL-18 and IL-5-deficient-Fabpi-IL-18 mice compared with Fabpi-IL-18 transgenic mice. Notably, jejunum eosinophilia in IL-5-deficient-Fabpi-IL-18 mice is significantly induced compared with wild-type mice, which indicates the direct role of induced IL-18 in the tissue accumulation of eosinophils and mast cells. Furthermore, we also found that overexpression of IL-18 in the intestine promotes eosinophil-associated peanut-induced allergic responses in mice. Taken together, we provide direct in vivo evidence that induced expression of IL-18 in the enterocytes promotes eotaxin-1, IL-5 and IL-13 independent intestinal eosinophilia, which signifies the clinical relevance of induced IL-18 in eosinophil-associated gastrointestinal disorders (EGIDs) to food allergens.

Eosinophilic Gastroenteritis and Colitis: a Comprehensive Review

Eosinophilic gastrointestinal disorders, including eosinophilic esophagitis, gastroenteritis, and colitis, refer to a spectrum of clinical diseases that present with variable degrees of infiltration of the gastrointestinal tract by eosinophils in the absence of other known causes of tissue eosinophilia. Clinical symptoms and laboratory findings are usually non-specific and may or may not be accompanied by peripheral blood eosinophilia. The extent of eosinophilic infiltration of the gastrointestinal wall varies from mucosal to transmural and serosal involvement. Diagnosis requires presence of gastrointestinal symptoms, demonstration of gastrointestinal eosinophilia by biopsy, and exclusion of other known causes of tissue eosinophilia. Many studies have pointed toward the eosinophil as the major offender; however, the exact functional role of the eosinophil in the pathogenesis of eosinophilic gastrointestinal disorders remains unclear. The roles of T-helper-2 cytokines and other mediators, such as eotaxin-1 and interleukin-5, have gained significant importance in the pathobiology of eosinophilic gastrointestinal disorders. Current understanding of treatment is based on case reports and a few case series, as there is a lack of large prospective studies. Steroids are currently the mainstay of therapy, but the roles of other drugs such as leukotriene inhibitors, mast cell stabilizers, interleukin-5 inhibitors, and anti-immunoglobulin E, along with other targets in the immune pathway, are currently being explored.

Mast Cells and Irritable Bowel Syndrome: From the Bench to the Bedside

Irritable bowel syndrome (IBS) is traditionally defined as a functional disorder since it lacks demonstrable pathological abnormalities. However, in recent years, low grade inflammatory infiltration, often rich in mast cells, in both the small and large bowel, has been observed in some patients with IBS. The close association of mast cells with major intestinal functions, such as epithelial secretion and permeability, neuroimmune interactions, visceral sensation, and peristalsis, makes researchers and gastroenterologists to focus attention on the key roles of mast cells in the pathogenesis of IBS. Numerous studies have been carried out to identify the mechanisms in the development, infiltration, activation, and degranulation of intestinal mast cells, as well as the actions of mast cells in the processes of mucosal barrier disruption, mucosal immune dysregulation, visceral hypersensitivity, dysmotility, and local and central stress in IBS. Moreover, therapies targeting mast cells, such as mast cell stabilizers (cromoglycate and ketotifen) and antagonists of histamine and serotonin receptors, have been tried in IBS patients, and have partially exhibited considerable efficacy. This review focuses on recent advances in the role of mast cells in IBS, with particular emphasis on bridging experimental data with clinical therapeutics for IBS patients.

Non-pulmonary allergic diseases and inflammatory bowel disease: A qualitative review

While the etiological underpinnings of inflammatory bowel disease (IBD) are highly complex, it has been noted that both clinical and pathophysiological similarities exist between IBD and both asthma and non-pulmonary allergic phenomena. In this review, several key points on common biomarkers, pathophysiology, clinical manifestations and nutritional and probiotic interventions for both IBD and non-pulmonary allergic diseases are discussed. Histamine and mast cell activity show common behaviors in both IBD and in certain allergic disorders. IgE also represents a key immunoglobulin involved in both IBD and in certain allergic pathologies, though these links require further study. Probiotics remain a critically important intervention for both IBD subtypes as well as multiple allergic phenomena. Linked clinical phenomena, especially sinonasal disease and IBD, are discussed. In addition, nutritional interventions remain an underutilized and promising therapy for modification of both allergic disorders and IBD. Recommending new mothers breastfeed their infants, and increasing the duration of breastfeeding may also help prevent both IBD and allergic diseases, but requires more investigation. While much remains to be discovered, it is clear that non-pulmonary allergic phenomena are connected to IBD in a myriad number of ways and that the discovery of common immunological pathways may usher in an era of vastly improved treatments for patients.

Accumulation of Mast Cells in the Lesions and Effects of Antiallergic Drugs on the Patients with Inflammatory Bowel Disease

The pathomechanism of inflammatory bowel disease (IBD) has not yet been fully demonstrated. However, it is well known that mast cells are present in the gastrointestinal tract, suggesting that mast cells may take part in it. So, we investigated the number of mast cells in IBD, such as ulcerative colitis (UC) and eosinophilic colitis, and showed that the number of mast cells was increased in the inflammatory lesions. We also presented a case of UC which was treated successfully with an antiallergic drug, tranilast. Furthermore, possible new approaches to treating the disease with immunomodulators including suplatast are introduced. However, our investigations were performed with a limited number of patients with IBD, and additional further studies are required to confirm the findings.

Role of serological markers of activated eosinophils in inflammatory bowel diseases

BACKGROUND

Activated eosinophils can infiltrate the intestinal mucosa in patients with inflammatory bowel disease (IBD), and eosinophils are also implicated in the histological damage seen in allergic diseases.

AIM

To assess, in a group of patients with IBD in remission or with a mild disease activity, whether serological markers of eosinophil activation, eosinophil cationic protein (ECP) and eosinophil protein X (EPX), are related to evidence of IgE hypersensitivity and to the eosinophilia in gut mucosa.

METHODS

Sixty-one patients with IBD (21 Crohn's disease and 40 ulcerative colitis) in remission or with a mild disease activity were screened for IgE hypersensitivity and serological levels of ECP and EPX. Colonic biopsies were taken to assess mucosal eosinophilic infiltration.

RESULTS

Skin prick test were positive in 31.1% of the patients with IBD, showing skin reactions to food allergens in 17.7%. Skin prick test findings were unrelated to ECP or EPX levels, or to clinical activity or eosinophil counts in the gut mucosa. A significant correlation was found between ECP and EPX levels (r=0.77; P<0.0001).

CONCLUSION

Serological ECP and EPX findings did not correlate with IgE hypersensitivity findings or eosinophilic colonic infiltration in patients with IBD in remission or with mild disease activity. The role of eosinophils in IBD needs to be better characterized in the colonic mucosa, instead of relying on serological tests.

Eosinophil survival and apoptosis in health and disease

Eosinophilia is common feature of many disorders, including allergic diseases. There are many factors that influence the production, migration, survival and death of the eosinophil. Apoptosis is the most common form of physiological cell death and a necessary process to maintain but limit cell numbers in humans and other species. It has been directly demonstrated that eosinophil apoptosis is delayed in allergic inflammatory sites, and that this mechanism contributes to the expansion of eosinophil numbers within tissues. Among the proteins known to influence hematopoiesis and survival, expression of the cytokine interleukin-5 appears to be uniquely important and specific for eosinophils. In contrast, eosinophil death can result from withdrawal of survival factors, but also by activation of pro-apoptotic pathways via death factors. Recent observations suggest a role for cell surface death receptors and mitochondria in facilitating eosinophil apoptosis, although the mechanisms that trigger each of these death pathways remain incompletely delineated. Ultimately, the control of eosinophil apoptosis may someday become another therapeutic strategy for treating allergic diseases and other eosinophil-associated disorders.

Relationship between mast cells and the colitis with relapse induced by trinitrobenzesulphonic acid in Wistar rats

The present study aimed to clarify the role of mast cells in colitis with relapse induced in Wistar rats by trinitrobenzenosulphonic acid. Colitis induction increased the histamine concentration in the colon, which peaked on day 26. The number of mast cells, probably immature, was ten times higher on day 8. Different from animals infected with intestinal parasites, after colitis remission, mast cells do not migrate to the spleen, showing that mast cell proliferation presents different characteristics depending on the inflammation stimuli. Treatment with sulfasalazine, doxantrazole, quercetin, or nedocromil did not increase the histamine concentration or the mast cell number in the colon on day 26, thereby showing absence of degranulation of these cells. In conclusion, although mast cell proliferation is associated with colitis, these cells and their mediators appear to play no clear role in the colitis with relapses.

General laboratory diagnostics of eosinophilic GI diseases

Eosinophils and gastrointestinal tract interact in an intimate and enigmatic relationship. Under inflammatory conditions, eosinophil infiltration in the gastrointestinal tract is a common feature of numerous eosinophilic gastrointestinal disorders (EGIDs). EGIDs are disorders, for which the diagnosis is relatively difficult. Nevertheless, some common laboratory techniques are currently used for their diagnosis and disease monitoring. Besides eosinophils, mast cells and T cells have also been suggested to play a role in the pathogenesis of these disorders. Here, we review the pathogenesis and common laboratory approaches applied for their diagnosis, in particular eosinophil and mast cell markers.

Eosinophils: biological properties and role in health and disease

Eosinophils are pleiotropic multifunctional leukocytes involved in initiation and propagation of diverse inflammatory responses, as well as modulators of innate and adaptive immunity. In this review, the biology of eosinophils is summarized, focusing on transcriptional regulation of eosinophil differentiation, characterization of the growing properties of eosinophil granule proteins, surface proteins and pleiotropic mediators, and molecular mechanisms of eosinophil degranulation. New views on the role of eosinophils in homeostatic function are examined, including developmental biology and innate and adaptive immunity (as well as their interaction with mast cells and T cells) and their proposed role in disease processes including infections, asthma, and gastrointestinal disorders. Finally, strategies for targeted therapeutic intervention in eosinophil-mediated mucosal diseases are conceptualized.

Eosinophilic gastroenteritis: a review

Eosinophilic gastroenteritis is a rare benign disease characterized by tissue eosinophilic infiltration that may involve several digestive tract layers. Also known as allergic, or eosinophilic allergic, gastroenteropathy, it usually involves the stomach and small intestine: rarely the colon. It may or may not be accompanied by higher counts of eosinophils in the peripheral blood. The main clinical manifestations depend on the site affected. It has been classified according to clinical and pathological features, and the symptoms depend on the patient's immunological response to several cytokines released by eosinophils. Because of lack of understanding of the etiology and triggering factors, treatment is based mainly on corticosteroids; although other drugs acting on the immune system have been tested, the results are not always satisfactory. This review focuses on the epidemiology, pathophysiology, clinical features, and treatment of this hitherto under-diagnosed disease.

Gastrointestinal eosinophilia

Gastrointestinal eosinophilia, a broad term for abnormal eosinophil accumulation in the gastrointestinal tract, involves many different disease identities. These diseases include primary eosinophil associated gastrointestinal diseases, gastrointestinal eosinophilia in hypereosinophilic syndrome, and all gastrointestinal eosinophilic states associated with known causes. Each of these diseases has its unique features but there is no absolute boundary between them. All three groups of gastrointestinal eosinophila are described in this article, although the focus is on primary gastrointestinal eosinophilia.

Submucosal connective tissue-type mast cells contribute to the production of lysophosphatidic acid (LPA) in the gastrointestinal tract through the secretion of autotaxin (ATX)/lysophospholipase D (lysoPLD)

Lysophosphatidic acid (LPA) is involved in a broad spectrum of biological activities, including wound healing and cancer metastasis. Autotaxin (ATX), originally isolated from a melanoma supernatant as a tumor cell motility-stimulating factor, has been shown to be molecularly identical to lysophospholipase D (lysoPLD), which is the main enzyme in the production of LPA. Although ATX/lysoPLD is known to be widely expressed in normal human tissues, the exact distribution of ATX-producing cells has not been fully investigated. In this study, we evaluated ATX/lysoPLD expression by immunohistochemical staining using a rat anti-ATX mAb in the human gastrointestinal tract and found that submucosal mast cells (MC) highly expressed this enzyme. This was confirmed by immunofluorescent double staining using mAbs to tryptase and chymase. Then, we isolated MC from human gastric tissue by an immunomagnetic method using CD117-microbeads and showed that a subpopulation of CD203c-positive MC showed positive staining for intracellular ATX/lysoPLD on flowcytometry. This was confirmed by Western blotting of the isolated cells. Moreover, a significant level of ATX/lysoPLD release could be detected in the culture supernatants of human MC by Western blot analysis. Our data suggest that submucosal MC play significant roles in various aspects of pathophysiology in the gastrointestinal tract by locally providing bioactive LPA through the production of ATX/lysoPLD.

Increase of mast cells may be associated with infiltration of eosinophils and proliferation of microvessels in gastric eosinophilic granuloma

BACKGROUND

Gastric eosinophilic granuloma (GEG) is a rare disease. Recently this disease has begun to increase in China. In the present study, the function and the role of mast cells (MC) in the pathogenesis of GEG were investigated.

METHODS

Paraffin-embedded tissue sections from 23 GEG patients and 15 gastric ulcer (GU) patients, were stained with antihuman mast cell tryptase for counting the MC and degranulated MC. Antihuman CD34 antibody was used for detecting the microvessel density (MVD) with immunohistochemical technique. Mast cell degranulation was also studied using electron microscopy.

RESULTS

The quantity of both MC and degranulated MC were higher in both GEG and GU than in normal gastric mucosa. The proportion of degranulated MC was higher in the GEG but in GU it was similar to normal mucosa. The MVD was higher in both GU and GEG than that in the normal gastric mucosa and it was higher in the high-MC group than in the low-MC group in GEG. The positive correlation between eosinophil and MC was present only in GEG, not in GU.

CONCLUSIONS

The infiltration of eosinophils and MVD may be associated with the increase of MC in GEG. This suggests that in addition to eosinophils, MC might be the important cells in the pathogenesis of GEG.

Accumulation of mast cells in the interstitium of eosinophilic colitis

INTRODUCTION

The mechanism of eosinophilic colitis remains unclear, and no case has been reported in which the number of mast cells was examined.

CASE REPORT

A 35-year-old man presented to our hospital with chief complaints of chills and consistent watery diarrhea after eating raw fresh-water fish. In blood examination, peripheral blood eosinophilia was found. Histological examination from biopsy specimens of both the ascending colon and rectum showed a prominent eosinophilic infiltration in the intestinal mucosa. Although a provocation test could not be performed due to lack of informed consent, a diagnosis of eosinophilic colitis was made on the basis of other findings. Immunohistochemical staining for human mast cell tryptase using monoclonal antibody against human mast cell tryptase showed an accumulation of mast cells in the colonic interstitium.

CONCLUSIONS

We report a case of eosinophilic colitis in which an accumulation of mast cells in the colonic interstitium was demonstrated.

Los granulocitos eosinófilos: de residentes habituales de la mucosa gastrointestinal normal a protagonistas agresivos de la gastroenteritis eosinofílica

Because of their biological affinity for normal gastrointestinal (GI) mucosa, eosinophilic granulocytes are "normal residents" in the mucosa. This physiological GI eosinophilia translates into a state of "permanent normal inflammation", which means that the mucosa's local immune system is constantly confronted by dietary proteins and indigenous microorganisms. This eosinophilic infiltration of the GI mucosa is increased, reactively, in the course of local inflammatory processes, collagenosis, infections (especially helminthic infections), vasculitis, neoplasms and IgE-dependent allergic reactions to food. Lastly, GI eosinophilia that is clearly aggressive, both because of its intensity and its persistence, is what characterizes eosinophilic gastroenteritis. In the present article, we summarize the ethiopathogenic and clinico-epidemiological features of this process, as well as its position within the field of immunopathologic food intolerance.

Food intolerance and skin prick test in treated and untreated irritable bowel syndrome

AIM: To correlate the clinical features of treated and untreated patients with irritable bowel syndrome (IBS) to the results of skin prick test (SPT) for food and inhalant allergens.

METHODS: We recruited 105 subjects to form three different target groups: treated group (n = 44) undergoing treatment for IBS, untreated group (n = 31) meeting the Rome II criteria without treatment for IBS, control group (n = 30) with no IBS symptoms.

RESULTS: SPT results were different among the three groups in which SPT was positive in 17 (38.6%) treated patients, in 5 (16.1%) untreated patients and in 1 (3.3%) control (P < 0.01). The number of positive SPTs was greater in the IBS group than in the control group (P < 0.001). The number of positive food SPTs was higher in the treated IBS group than in the untreated IBS group (P = 0.03).

CONCLUSION: Positive food SPT is higher in IBS patients than in controls.

Cell surface membrane antigen phenotype of human gastrointestinal mast cells

BACKGROUND

Mast cells (MC) are important effector cells of allergic and inflammatory reactions in diverse organs. These cells interact with a number of other immune cells and structural cells in the tissues as well as with proinflammatory mediators and cytokines. The various interactions are considered to be mediated through distinct cell surface membrane receptors on MC.

METHODS

In the present study, we have established the cell surface membrane phenotype of human gastrointestinal MC (HGMC) using a panel of monoclonal antibodies and indirect immunofluorescence staining techniques.

RESULTS

HGMC were found to react with antibodies against CD29, CD33, CD44, CD45, CD47, CD54, CD55, CD58, CD63, CD117, CD147, CD151, CD172a, and CD203c. By contrast, HGMC did not express detectable amounts of CD1, CD2, CD4, CD5, CD14, CD15, CD16, CD22, CD24, CD25, CD26, CD27, CD28, CD31, CD32, CD34, CD35, CD88, or CD116. The alpha-chain of the IL-3 receptor (CD123) was detectable neither in resting HGMC nor in HGMC exposed to stem cell factor and interleukin-4.

CONCLUSIONS

HGMC express a unique profile of surface antigens including the receptor for mast cell growth factor, adhesion-related molecules, and activation-linked membrane antigens.

Evaluation of mucosal eosinophils in the pediatric colon

To evaluate the clinical significance of colonic eosinophilia, we conducted a retrospective study of all children older than 1 year evaluated at Children's Hospital of Pittsburgh from January 1999 to June 2001 with a description of colonic eosinophilia in the pathology report. Medical records were reviewed. Diagnoses were confirmed by contacting the patients. Histological slides (H&E) were reviewed by an investigator blind to the patients' data. Biopsies were grouped according to the site they were taken from and then screened at low power for areas of maximal eosinophilia for further quantitative analysis. Results of manual counts were validated by image analysis using Metaphor Image Analysis Software. Sixty-nine children with colonic eosinophilia were identified (36 male; mean age, 135.2 +/- 55.4 months). Their final diagnoses were inflammatory bowel disease in 32% (group A), irritable bowel syndrome in 33% (group B), food allergies in 10% (group C), and other diagnoses in 25% (group D). The maximal eosinophil count per crypt area was significantly (P < 0.05) higher in group A vs groups B, C, and D (34.8 +/- 17.1 vs 21.3 +/- 8.8, 25.4 +/- 16.7, and 24.2 +/- 9.7, respectively). The total cellularity of the lamina propria was considered high only in group A (P < 0.05 vs groups B and C). A mostly equal vertical distribution of eosinophils throughout the lamina propria was found significantly more frequently in group A vs groups C (P = 0.04) and D (P = 0.007). We conclude that children with inflammatory bowel disease have an equal distribution of eosinophils throughout the lamina propria, with intraepithelial and intracryptal eosinophils and with a higher overall total cellularity. In irritable bowel syndrome and patients with a variety of other diagnoses, including allergies, the distribution is mostly superficial, with a lower total cellularity.

Probiotic effects on faecal inflammatory markers and on faecal IgA in food allergic atopic eczema/dermatitis syndrome infants

Probiotic bacteria are proposed to alleviate intestinal inflammation in infants with atopic eczema/dermatitis syndrome (AEDS) and food allergy. In such infants we investigated effects of probiotic bacteria on faecal IgA, and on the intestinal inflammation markers tumour necrosis factor-alpha (TNF-alpha), alpha1-antitrypsin (AT), and eosinophil cationic protein (ECP). A total of 230 infants with AEDS and suspected cow's milk allergy (CMA) received in a randomized double-blinded manner, concomitant with elimination diet, Lactobacillus GG (LGG), a mixture of four probiotic strains (MIX), or placebo for 4 wk. Four weeks after treatment, CMA was diagnosed with a double-blind placebo-controlled milk challenge. Faecal samples of 102 infants, randomly chosen for analysis, were collected before treatment, after 4-wk treatment, and on the first day of milk challenge. After treatment, IgA levels tended to be higher in probiotic groups than in the placebo group (LGG vs. placebo, p=0.064; MIX vs. placebo, p=0.064), and AT decreased in the LGG group, but not in other treatment groups. After challenge in IgE-associated CMA infants, faecal IgA was higher for LGG than for placebo (p=0.014), and TNF-alpha was lower for LGG than for placebo, but non-significantly (p=0.111). In conclusion, 4-wk treatment with LGG may alleviate intestinal inflammation in infants with AEDS and CMA.

Technologies in the evaluation of irritable bowel syndrome

During a meeting in The Hague, The Netherlands, the IBiS Club evaluated the most important techniques that can be used in the investigation of irritable bowel syndrome, either in the context of scientific research or as a clinical diagnostic tool. In each of these, the relevance of findings made in irritable bowel syndrome was balanced against the applicability of the technique. The discussion of the group is summarized in this paper.

Mast cells are required for experimental oral allergen-induced diarrhea

Gastrointestinal allergic disorders represent a diverse spectrum of inflammatory diseases that are occurring with increasing incidence and severity. An essential question concerning these disorders is to determine the specific cells and mediators responsible for specific clinical manifestations. With this in mind, we developed a murine model of oral allergen-induced intestinal inflammation accompanied by strong Th2-associated humoral and cellular responses and focused on the immunopathogenesis of allergic diarrhea. Exposure of OVA/alum-sensitized mice to repeated doses of intragastric OVA induced genetically restricted, dose-dependent, acute diarrhea associated with increased intestinal permeability, eosinophilia, and mastocytosis. Mice developed limited systemic manifestations of anaphylaxis, even though they developed marked intestinal mucosal mast cell degranulation. Notably, experiments involving mast cell depletion (with anti-c-kit mAb), anti-IgE treatment, and Fc epsilon RI-deficient mice indicated a critical effector role for mast cells in mediating allergic diarrhea. Furthermore, allergic diarrhea was dependent upon synergistic signaling induced by serotonin and platelet-activating factor (PAF), but not histamine. These results demonstrate that oral allergen-induced diarrhea associated with experimental Th2 intestinal inflammation is largely mast cell, IgE, serotonin, and PAF dependent.

Functional and morphologic characterization of eosinophils in the lower intestinal mucosa of patients with food allergy

OBJECTIVE

The aim of this study was to characterize the functional and morphologic features of eosinophils in the intestinal mucosa of patients with food allergy.

METHODS

Eighteen patients with food allergy and 11 controls took part in this study. In every patient, corresponding biopsy samples obtained during colonoscopy were quantitatively assessed by immunohistochemical methods (EPO-I) and subjected to mucosa oxygenation using eosinophilic cationic protein (ECP). Initial basal release, spontaneous and anti-IgE-dependent release, and the total ECP content of mucosal biopsies were studied.

RESULTS

Morphologically, mucosal eosinophils in patients with food allergy have distinct features, occur in larger amounts, and show a distinct distribution pattern (i.e., intraepithelial, lamina propria, and submucosa). Their initial basal release is similar to that of controls, but stimulation of the IgE receptor with anti-IgE results in 40-fold activation (p < 0.001). In food allergy patients, the density of eosinophils, the presence of intraepithelial eosinophils, and the rate of degranulation showed a highly significant correlation to the initial basal release of ECP by mucosal tissue (Kendall tau = 0.619, 0.381, and 0.609, respectively; p < 0.05 for all) but not to their capability to be stimulated with anti-IgE.

CONCLUSIONS

Eosinophils of the lower intestine of patients with food allergy show characteristic features with regard to morphology, distribution, and functional behavior to IgE receptor stimulation. Immunostaining of eosinophil peroxidase (EPO) detects important characteristic features that are missed with conventional hematoxylin-eosin staining.

The nature of colitis in chronic granulomatous disease

BACKGROUND

Patients with chronic granulomatous disease (CGD) may have gastrointestinal manifestations, commonly colitis. The etiology, prevalence, and inflammatory process of CGD colitis are unclear.

OBJECTIVES

To characterize the inflammatory process of CGD colitis and to compare it with other inflammatory bowel disorders.

METHODS

Colonic mucosal biopsies from 8 CGD patients were immunostained for eosinophils, neutrophils, macrophages, and adhesion molecules (ICAM; VCAM, E-selectin) and compared with normal and diseased controls (allergic colitis, ulcerative colitis, and melanosis coli). Cell types were counted and expressed as cell/mm2.

RESULTS

The inflammatory infiltrate in CGD colitis differed from the normal controls by an increase in eosinophils (110; 48-176 [median and range] versus 14.5; 3-30; P < 0.005) and macrophages (291.5; 203-480 versus 38.5; 27-64; P < 0.005). There was a paucity of neutrophils compared to ulcerative colitis (10; 0-101 versus 315.5; 78-688; P < 0.005). Expression of HLA-DR was increased in the epithelium and vascular endothelium in CGD compared with normal controls. Patterns of expression of the adhesion molecules differed significantly in CGD from those in other inflammatory bowel diseases: intracellular adhesion molecule-1 was more strongly expressed in the lamina propria, vascular adhesion molecule-1 was more patchily expressed, and E-selectin was present only in the small vessels.

CONCLUSIONS

The mechanism of inflammation and profile of inflammatory mediators in CGD colitis differs from that in other inflammatory bowel diseases.

Eosinophilic gastroenteritis: epidemiology, diagnosis and management

Eosinophilic gastroenteritis is a heterogeneous and uncommon disorder characterized by eosinophilic inflammation of the gastrointestinal tissues. The location and depth of infiltration determine its varied manifestations, and the latter is also the basis for the proposed classification into mucosal, muscular and serosal eosinophilic gastroenteritis. Abdominal pain, vomiting, and diarrhea are each present in nearly 50% of the patients, with some overlap. Peripheral eosinophilia is seen in approximately two-thirds of patients with eosinophilic gastroenteritis. It is now clear that eotaxin, a specific eosinophil chemoattractant, plays a pivotal role in the process of eosinophil production. The differential diagnosis of eosinophilic gastroenteritis in children includes parasitic infections, inflammatory bowel disease, connective tissue diseases, some malignancies and adverse effects of drugs. Eosinophilic gastroenteritis itself has been strongly associated with food allergies, and concomitant atopic diseases or a family history of allergies is elicited in about 70% of cases. The pediatric experience is unique with respect to recognition of distinctive entities such as allergic procto-colitis, almost exclusively seen in infants, and eosinophilic esophagitis being increasingly reported among children and young adults. The gold standard for diagnosis, usually demonstrated on endoscopic biopsies, is prominent tissue eosinophilia. However, the diagnosis may be obscured by the patchy nature of the disease, and muscular and serosal eosinophilic gastroenteritis subtypes. In the latter cases, full thickness biopsies would be indicated for a definitive diagnosis. There are many reports of successful treatment of eosinophilic gastroenteritis in children, using a variety of treatment regimens including elimination diets. Corticosteroids remain the most effective agents for controlling symptoms, but unfortunately the relapsing nature of the disease would mandate prolonged corticosteroid use. Reports of favorable responses to new leukotriene inhibitors in patients with eosinophilic gastroenteritis are encouraging; these responses should stimulate future research on the pathophysiology and management of eosinophilic gastroenteritis.

Markers of inflammation in the feces of infants with cow's milk allergy

Growing evidence exists that exposure to cow's milk elicits inflammation in the gut of infants with cow's milk allergy, irrespective of symptoms. To demonstrate inflammation and increased protein leakage from the gut during a cow's milk elimination-challenge test in fecal samples of infants presenting with different symptoms suggestive of cow's milk allergy, we measured the concentrations of alpha1-antitrypsin (AT), eosinophil cationic protein (ECP), immunoglobulin (Ig) A, and cow's milk-specific IgA antibodies, in fecal samples of 208 infants with a mean age of 7 months. Prechallenge samples were collected after a mean 3-week elimination period, and post-challenge samples were obtained 4 days after starting the challenge. Fecal levels of prechallenge total IgA (p = 0.02) and post-challenge AT (p = 0.001) were higher in infants with a positive challenge. Of these infants, pre- and post-challenge levels of ECP were higher in those reacting after 24 h than in those reacting within 1 h (p = 0.006 and p = 0.045). Prechallenge levels of ECP were higher in those showing intestinal symptoms (p = 0.008), and both pre- and post-challenge levels of total IgA were higher in those with an IgE-mediated reaction to cow's milk (p = 0.04 and p = 0.008). Regardless of the challenge result, total IgA increased during the challenge (p < 0.001 for both challenge-positive and -negative infants) and was higher in those breast-fed until the challenge than in those fed formula only (p < 0.01). Hence, in infants reacting to the cow's milk challenge, higher prechallenge levels of fecal IgA indicate increased antigenic stimuli in the gut, and higher post-challenge levels of AT reflect increased protein loss as a result of intestinal inflammation. In infants with slowly evolving gastrointestinal symptoms, increased fecal ECP may help in distinguishing patients from those who tolerate cow's milk. Individual serial follow-up of fecal IgA and ECP can be used to estimate the degree of inflammation in the gut and an appropriate time for a challenge test, but are not diagnostic tools for cow's milk allergy.

Enterocyte expression of the eotaxin and interleukin-5 transgenes induces compartmentalized dysregulation of eosinophil trafficking

Eosinophils accumulate in the gastrointestinal tract in a number of medical disorders, but the mechanisms involved are largely unknown. To understand the significance of cytokine expression by enterocytes, enterocyte transgenic mice that overexpressed the eosinophil-selective cytokines eotaxin and interleukin (IL)-5 were generated. Transgenic mice, generated by utilizing the rat intestinal fatty acid-binding protein promoter (Fabpi), overexpressed the mRNA for these cytokines in the small intestine. Overexpression of IL-5 resulted in marked increases of eosinophils in the bone marrow and blood, whereas eotaxin overexpression resulted in similar levels compared with nontransgenic control mice. In contrast, both IL-5 and eotaxin transgenic mice had significant accumulation of eosinophils in the gastrointestinal mucosa compared with control mice. Eotaxin-induced gastrointestinal eosinophilia was substantially higher than that induced by IL-5 and was especially prominent within the lamina propria of the villi. Interestingly, genetic rescue of eotaxin deficiency (by transgenic overexpression of eotaxin in eotaxin gene-targeted mice) resulted in significant restoration of gastrointestinal eosinophil levels. Finally, the intestinal eosinophilia induced by the eotaxin transgene was beta(7) integrin-dependent. Taken together, these results demonstrate that expression of eotaxin and IL-5 in intestinal epithelium induces compartmentalized dysregulation of eosinophil trafficking and the important role of the beta(7) integrin in gastrointestinal allergic responses.

Non-invasive investigation of inflammatory bowel disease

The assessment of inflammatory activity in intestinal disease in man can be done using a variety of different techniques. These range from the use of non-invasive acute phase inflammatory markers measured in plasma such as C reactive protein (CRP) and the erythrocyte sedimentation rate (ESR) (both of which give an indirect assessment of disease activity) to the direct assessment of disease activity by intestinal biopsy performed during endoscopy in association with endoscopic scoring systems. Both radiology and endoscopy are conventional for the diagnosis of inflammatory bowel disease (IBD). However these techniques have severe limitations when it comes to assessing functional components of the disease such as activity and prognosis. Here we briefly review the value of two emerging intestinal function tests. Intestinal permeability, although ideally suited for diagnostic screening for small bowel Crohn’s disease, appears to give reliable predictive data for imminent relapse of small bowel Crohn’s disease and it can be used to assess responses to treatment. More significantly it is now clear that single stool assay of neutrophil specific proteins (calprotectin, lactoferrin) give the same quantitative data on intestinal inflammation as the 4-day faecal excretion of 111Indium labelled white cells. Faecal calprotectin is shown to be increased in over 95% of patients with IBD and correlates with clinical disease activity. It reliably differentiates between patients with IBD and irritable bowel syndrome. More importantly, at a given faecal calprotectin concentration in patients with quiescent IBD, the test has a specificity and sensitivity in excess of 85% in predicting clinical relapse of disease. This suggests that relapse of IBD is closely related to the degree of intestinal inflammation and suggests that targeted treatment at an asymptomatic stage of the disease may be indicated.

Food hypersensitivity and irritable bowel syndrome

Irritable bowel syndrome is a common condition but its pathophysiology remains poorly understood. Many irritable bowel syndrome patients give a history of food intolerance, but data from dietary elimination and re-challenge studies are inconclusive. Multiple aetio-pathological mechanisms have been postulated. The gut has an extensive immune system but current understanding of processing of food antigens in health and disease is limited. There is no clinically useful marker available to test for food hypersensitivity in irritable bowel syndrome. Researchers have employed both skin tests and serum immunoglobulins (IgG and IgE) as markers of food hypersensitivity in various disorders including irritable bowel syndrome, but published data are equivocal. In this article, the evidence for the role of food hypersensitivity in irritable bowel syndrome is reviewed and, based on the available data, a possible pathophysiological hypothesis has been formulated.

Colitis in chronic granulomatous disease

BACKGROUND

Involvement of the gut in chronic granulomatous disease (CGD) has been previously described and colitis highlighted. However, the nature and histopathology of the colitis are unclear and have been thought to be non-specific or similar to Crohn's disease.

METHODS

Seven patients with CGD, suffering from gastrointestinal symptoms were prospectively studied.

RESULTS

All patients had anaemia; other symptoms were failure to thrive (5/7) and diarrhoea (5/7). Most had microcytic anaemia (5/7), increased platelets (7/7), and increased erythrocyte sedimentation rate (6/6). Endoscopically there was a friable erythematous mucosa in 6/7. The histological features present in all patients consisted of a colitis with paucity of neutrophils, increased numbers of eosinophils, eosinophilic crypt abscesses, pigmented macrophages, and nuclear debris. In some granulomas were present (2/7).

CONCLUSIONS

Colitis is a common cause of gastrointestinal symptoms in CGD and is caused by a non-infective inflammatory process. The histology has specific features, which are distinctive from those seen in Crohn's disease.

Eosinophilic gastroenteritis

The goal to create a standardized diagnostic classification scheme of food-related gastrointestinal hypersensitivity disease syndromes included the diagnosis of eosinophilic gastroenteritis. This article reviews the history of this diagnosis and the current concepts of this complex disorder. The common symptoms from the literature are discussed. Because no standards for this diagnosis exist, the wide variety of diagnostic criteria from the literature are presented. No consistent immunologic abnormalities have been associated with the diagnosis of eosinophilic gastroenteritis in the literature. A review of the current immunologic concepts associated with the diagnosis of eosinophilic gastroenteritis is presented. The history of this disorder, which spans more than 6 decades is also discussed. The contributions made by the original authors during this period are presented. Attention was directed to the variety of clinical features associated with this disorder, but particular attention was paid to the evolution of the pathophysiologic mechanisms proposed. Some of the difficulties associated with the prospective study of patients with eosinophilic gastroenteritis are also discussed. The establishment of appropriate control populations, as well as the fundamental difficulties encountered with the establishment of the certainty of the link between abnormal immunohistochemical findings, and initial clinical symptoms are presented and discussed. A new classification system is proposed for food-related gastrointestinal hypersensitivity disease syndromes. Age, symptoms, and the region of the gastrointestinal tract involved were the variables that were considered most important by consensus opinion. Finally, recommendations to refocus our collective investigative efforts are presented.

Discrepancies between reported food intolerance and sensitization test findings in irritable bowel syndrome patients

OBJECTIVE

Irritable bowel syndrome (IBS) is a common gastrointestinal disorder with clinical signs typical of "intestinal" food allergies or intolerance. The aim of this study was to characterize the clinical features of IBS patients suspected of suffering from adverse reactions to food.

METHODS

The study involved 128 consecutive IBS patients divided into four groups according to their main symptom on presentation at our outpatient clinic. A detailed medical history was recorded, paying particular attention to any allergies and reported intolerance to food. Each patient was screened for allergies; intestinal permeability tests was performed in randomly selected patients from different groups. Findings were analyzed using the chi2 test.

RESULTS

Adverse reactions to one or more foods were reported by 80 patients (62.5%); skin prick tests (SPT) were positive in 67 patients (52.3%) with no significant differences between patients complaining of different symptoms. Patients who reported a food intolerance had more positive SPTs than those who did not (47 of 80 [58.7%] vs 20 of 48 [41.7%]); this difference was not statistically significant, although it suggests a trend (p < 0.0610). There was little consistency between the specific foods reported to cause intolerance and those resulting from the tests (11 of 80 patients, 13.7%). The intestinal permeability test was normal in 29 of 33 patients (87.9%).

CONCLUSIONS

More than 50% of IBS patients were found sensitized to some food or inhalant without any typical clinical signs. Patients were unable to identify potentially offending foods. The lack of a correlation between SPT results and reported food allergies needs further investigation to clarify the pathophysiology and improve the diagnosis of intestinal food allergies.

Eosinophilic gastroenterocolitis in iron lactate-overloaded rats

Eosinophilic gastroenterocolitis with peripheral eosinophilia was induced in rats fed a diet containing 2.5% or 5.0% iron lactate for 3 mo. Additional findings consistent with iron overload were also observed. Microscopically, the lesions consisted of eosinophilic infiltrations in the mucosa and submucosa along the whole length of the gastrointestinal tracts, increased surface area of the gastric mucosal propria covered with mucous cells, and increased apoptotic bodies in the gastric glandular neck of rats in the 2.5% and 5.0% groups. An increased number of intraepithelial globule leukocytes in the gastric and intestinal lamina propria was also observed in the 5.0% group. Globule leukocytes in the gastric mucosa contained obviously enlarged granules in their cytoplasm in these rats. The granules of the globule leukocytes were positive for rat mast cell protease II, suggesting the mastocyte origin of these cells. Although severe infiltration of eosinophils and globule leukocytes suggested a type-1 hypersensitivity reaction, other features such as an increasing vascular permeability were not detected. Serum IgE levels in the 5.0% and control groups were < 3 ng/ml. Final body weights of male and female rats of the 5.0% group were suppressed to 70% and 90%, respectively, of those of the control rats, whereas food consumption was comparable to that of the control group. The morphologic characteristics of the gastrointestinal lesions and peripheral eosinophilia induced in rats fed iron lactate were very similar to those in some cases of eosinophilic gastroenterocolitis in humans and other animals.

Mast cells: a possible link between psychological stress, enteric infection, food allergy and gut hypersensitivity in the irritable bowel syndrome

Intestinal mast cell activation (degranulation), which results from previous enteric infection and/or intestinal allergy, may play a central role in the gut hypersensitivity in both motor response and visceral perception in the Irritable Bowel syndrome. This occurs through various mediators acting on enteric neurons and smooth muscle cells. Psychological stress may trigger this sensitive alarm system via the brain-gut axis.