Mast cells and IgE in intestinal mucosa in adult atopic dermatitis patients

Mast cells in food allergy: Inducing immediate reactions and shaping long-term immunity

Mast cells are distributed throughout the gastrointestinal tract and function as the main effector cells of IgE-mediated allergic reactions to foods. Allergen-induced cross-linking of IgE antibodies bound to high-affinity IgE receptors, FcεRI, on the surface of mast cells triggers their activation, resulting in the release of mediators of immediate hypersensitivity. These mediators rapidly induce both local gastrointestinal and systemic physiological responses including anaphylaxis. Emerging evidence has revealed that, in addition to inciting immediate reactions, mast cells are key regulators of adaptive immunity to foods. In the gastrointestinal mucosa they provide the priming cytokines that initiate and, over time, consolidate adaptive T_H2 responses to ingested allergens as well as TNF and chemokines that orchestrate the recruitment of tissue-infiltrating leukocytes that drive type 2 tissue inflammation. Patients with atopic dermatitis have increased intestinal mast cell numbers and are at a greater risk for food allergy. Recent studies have uncovered a skin-gut axis in which epicutaneous allergen exposure drives intestinal mast cell expansion. The activating effects of IgE antibodies in mast cells are countered by food-specific IgG antibodies that signal via the inhibitory IgG receptor, FcγR2b, suppressing both immediate allergic reactions to foods and the type 2 immune adjuvant activity of mast cells.

Mechanical Skin Injury Promotes Food Anaphylaxis by Driving Intestinal Mast Cell Expansion

Mast cell (MC) mediator release after crosslinking of surface-bound IgE antibody by ingested antigen underlies food allergy. However, IgE antibodies are not uniformly associated with food allergy, and intestinal MC load is an important determinant. Atopic dermatitis (AD), characterized by pruritis and cutaneous sensitization to allergens, including foods, is strongly associated with food allergy. Tape stripping mouse skin, a surrogate for scratching, caused expansion and activation of small intestinal MCs, increased intestinal permeability, and promoted food anaphylaxis in sensitized mice. Tape stripping caused keratinocytes to systemically release interleukin-33 (IL-33), which synergized with intestinal tuft-cell-derived IL-25 to drive the expansion and activation of intestinal type-2 innate lymphoid cells (ILC2s). These provided IL-4, which targeted MCs to expand in the intestine. Duodenal MCs were expanded in AD. In addition to promoting cutaneous sensitization to foods, scratching may promote food anaphylaxis in AD by expanding and activating intestinal MCs.

Perceived food hypersensitivity: a review of 10 years of interdisciplinary research at a reference center

Perceived food hypersensitivity is a prevalent, but poorly understood condition. In this review article, we summarize narratively recent literature including results of our 10 years' interdisciplinary research program dealing with such patients. The patients (more than 400) included in our studies were all adults referred to a university hospital because of gastrointestinal complaints self-attributed to food hypersensitivity. Despite extensive examinations, food allergy was seldom diagnosed. The majority of the patients fulfilled the diagnostic criteria for irritable bowel syndrome. In addition, most suffered from several extra-intestinal health complaints and had considerably impaired quality of life. However, psychological factors could explain only approximately 10% of the variance in the patients' symptom severity and 90% of the variance thus remained unexplained. Intolerance to low-digestible carbohydrates was a common problem and abdominal symptoms were replicated by carbohydrate ingestion. A considerable number of patients showed evidence of immune activation by analyses of B-cell activating factor, dendritic cells and "IgE-armed" mast cells. Multiple factors such as immune activation, disturbed intestinal fermentation, enteric dysmotility, post-infectious changes and "local" allergy in the gut as well as psychological disturbances may play a role in the pathophysiology of perceived food hypersensitivity. Hence, our results support the view that management of these patients should be interdisciplinary.

Food: the forgotten factor in the irritable bowel syndrome

After years of inattention, there is a growing body of evidence to suggest that dietary constituents at least exacerbate symptoms and perhaps contribute to the pathogenesis of the irritable bowel syndrome (IBS). Although patients with IBS self-report food allergies more often than the general population, the evidence suggests that true food allergies are relatively uncommon. Less clearly defined food intolerances may be an important contributor to symptoms in IBS patients. This article reviews the literature supporting a causal link between food and the symptoms of IBS as well as the evidence supporting dietary interventions as a means of managing IBS symptoms.

Mast cells and IgE-containing cells in gastric mucosa of Helicobacter pylori infected and non-infected patients with chronic urticaria

BACKGROUND

Several studies have indicated that antibiotic therapy aimed at eradication of Helicobacter pylori has effects on symptoms of chronic urticaria (CU) patients. However, the possible connections and pathomechanism by which H. pylori might be linked to CU have remained largely unknown. The IgE-mediated pathway might be a possible link between H. pylori infection and CU. We therefore clarified the role of H. pylori as an inducer of IgE response.

MATERIALS AND METHODS

Gastroscopy was performed and mucosal biopsy specimens were taken to evaluate the histology, as well as the presence of H. pylori bacteria, mast cells and IgE-containing cells in the antral mucosa, in 21 CU patients. Controls (n = 48) included 19 patients with lichen planus, nine patients with atopic dermatitis and 20 patients with no skin or allergic disease.

RESULTS

The mean densities of IgE-containing cells were significantly higher in H. pylori-infected patients and in patients with skin disease compared to non-H. pylori-infected patients with no skin or allergic disease. No significant difference was found in the number of IgE-containing cells between H. pylori-infected and non-infected patients with CU. There was no significant difference in the mean densities of mast cells in the different patient groups.

CONCLUSIONS

Our findings suggest that H. pylori gastritis leads to increased IgE production. However, we could not show a significant difference in IgE staining between H. pylori-infected and non-infected patients with CU.

Effect of probiotic Lactobacillus strains in children with atopic dermatitis

BACKGROUND

Recent studies suggest that oral bacteriotherapy with probiotics might be useful in the management of atopic dermatitis (AD).

OBJECTIVE

The purpose of this investigation was to evaluate the clinical and anti-inflammatory effect of probiotic supplementation in children with AD.

METHODS

In a double-blind, placebo-controlled, crossover study, 2 probiotic Lactobacillus strains (lyophilized Lactobacillus rhamnosus 19070-2 and Lactobacillus reuteri DSM 122460) were given in combination for 6 weeks to 1- to 13-year-old children with AD. The patients' evaluations were registered after each intervention (ie, better, unchanged, or worse). The clinical severity of the eczema was evaluated by using the scoring atopic dermatitis (SCORAD) score. As inflammatory markers, eosinophil cationic protein in serum and cytokine production by PBMCs were measured.

RESULTS

After active treatment, 56% of the patients experienced improvement of the eczema, whereas only 15% believed their symptoms had improved after placebo (P =.001). The total SCORAD index, however, did not change significantly. The extent of the eczema decreased during active treatment from a mean of 18.2% to 13.7% (P =.02). The treatment response was more pronounced in allergic patients (at least one positive skin prick test response and elevated IgE levels), and in this group the SCORAD score decreased (P =.02 compared with nonallergic patients). During active treatment, serum eosinophil cationic protein levels decreased (P =.03). No significant changes in the production of the cytokines IL-2, IL-4, IL-10, or IFN-gamma were found.

CONCLUSIONS

A combination of L rhamnosus 19070-2 and L reuteri DSM 122460 was beneficial in the management of AD. The effect was more pronounced in patients with a positive skin prick test response and increased IgE levels.

Duodenal IgE-positive cells and elimination diet responsiveness in children with atopic dermatitis

BACKGROUND

Parameters for identifying eczematous children who could respond to an elimination diet are needed. In children with food allergy, duodenal IgE-containing cells are enhanced.

OBJECTIVE

To determine the presence of duodenal mucosal IgE-positive cells in atopic dermatitis and to determine whether duodenal IgE-positive cells may identify eczematous children who will benefit from an elimination diet.

METHODS

Thirty-one children with severe eczema underwent gastrointestinal endoscopy because of gastrointestinal symptoms and were treated with an elimination diet. A clinical score to skin lesions was given before and after diet. All subjects were skin-prick tested with food antigens and aeroallergens. Serum IgE levels were measured. Duodenal IgE-positive cells were investigated in 18 control subjects and in all eczematous children before diet.

RESULTS

The number of duodenal IgE-positive cells in children with atopic dermatitis was significantly increased compared with that of control group (P < 0.001). Nineteen (61%) eczematous children improved on a few food diet. Diet-responsive children had significantly higher IgE-positive cells compared with both nondiet-responsive and controls. Positive predictive accuracy of duodenal IgE-positive cells was poor, whereas negative predictive accuracy was high at the cutoff level of 50 IgE-positive cells/10 visual fields. Diagnostic accuracy both of SPT reactions with foods and of food-specific serum IgE antibodies was poor.

CONCLUSIONS

An intestinal IgE-mediated reaction occurred in children with severe atopic dermatitis who underwent intestinal endoscopy because of gastrointestinal symptoms. In these eczematous children, the number of IgE-positive cells in the duodenal mucosa might be helpful for excluding a positive response to the elimination diet.

Gastrointestinal symptoms in atopic eczema

AIMS

To determine the prevalence of gastrointestinal symptoms in children with eczema and the association of such symptoms with the extent of eczema or skin prick test results.

METHODS

Sixty five children with atopic eczema and a control group matched for age and sex were recruited. Their parents completed a questionnaire about the children's gastrointestinal symptoms. The children's skin was examined; their weight, height, and abdominal circumference were measured; and skin prick tests were carried out.

RESULTS

Gastrointestinal symptoms, especially diarrhea, vomiting, and regurgitation, were more common in the children with eczema. Diarrhea appeared to be associated with the ingestion of specific foods. Gastrointestinal symptoms were related to diffuse eczema and positive skin prick tests to foods. There was no anthropometric differences between the patient and control groups.

CONCLUSIONS

A gastrointestinal disorder is common in children with eczema, especially with diffuse distribution. This may be responsible for substantial symptoms and may play a part in the pathogenesis of the disease and in the failure to thrive with which it is sometimes associated.

Gastrointestinal stability of baker's yeast allergens: an in vitro study

An in vitro model was established to study the stability of baker's yeast (Saccharomyces cerevisiae) allergens in conditions simulating the gastrointestinal tract. The protocol consisted of 2 hr incubation under gastric conditions (pH 1.2, +37 degrees C and gastric enzymes) and 2 hr incubation under duodenal conditions (pH 6.8, +37 degrees C and duodenal enzymes). These were studied together and separately, as well as under pure acidic conditions without gastric enzymes. The yeast extracts contained equal amounts of allergen and were analyzed by IgE-immunoblotting. The acidic conditions had partly an enhancing and slightly degrading effect on the yeast allergens, whereas the gastric enzymes destroyed several allergens, including the important intermediate allergens of 31 and 45 kD. After treatment under both gastric and duodenal conditions most of the yeast allergens were destroyed, except mannan and a 10 kD protein component. The findings suggest that the allergen exposure caused by baker's yeast takes place mainly on the mucosal surfaces orally and oesophageally and through viable baker's yeast organisms that manage to pass the stomach and duodenum and possibly lead to intestinal growth of the organism. Patients with IgE production against the 10 kD allergen and mannan are, however, moderately exposed to allergens consisting of soluble antigenic material only.

Candida albicans and atopic dermatitis

The role of sensitization and exposure to Candida albicans in atopic dermatitis (AD) was studied with skin-prick tests, yeast cultures and immunoblotting in 156 young adults with AD attending the Department of Dermatology, University of Turku, during 1983-89. Eighteen patients with allergic rhinitis without eczema and 39 non-atopics were included as controls. Parameters associated with severe AD were simultaneous anti-C. albicans IgE and saprophytic C. albicans growth. A statistically significant correlation between C. albicans sensitization (specific IgE antibodies) and AD symptoms was observed only in patients with saprophytic C. albicans exposure. No correlation between C. albicans-specific IgE and AD severity was shown in patients without gastrointestinal growth. Furthermore, severe eczema was seldom seen in patients without saprophytic C. albicans growth. The most important IgE-binding components of C. albicans in immunoblotting were 27 and 46 kD proteins and mannan, a polysaccharide. IgG and IgA antibodies to C. albicans, mainly towards C. albicans mannan, were found in practically all 70 sera studied. These results suggest a continuous exposure and induction of IgE antibodies by C. albicans in AD patients. Severe phases of AD in colonized patients are associated with IgE synthesis against C. albicans. These findings suggest a role for C. albicans in the exacerbations of AD but the clarification of this subject needs double-blind placebo-controlled treatment trials.

IgE levels in faecal extracts of patients with food allergy

IgE levels in faecal extracts (Copro-IgE levels) were investigated in food allergy (FA) patients before and after the challenge test administration of food allergens. IgE levels were measured by time-resolved fluoroimmunometric assay. In addition, the effects of administration of oral sodium cromoglycate (SCG) on the Copro-IgE levels were studied. Copro-IgE levels in patients with FA, who were placed on an elimination diet, did not differ from those of healthy children. After a challenge test immediate symptoms of urticaria and wheezing were observed in all FA patients. Copro-IgE levels in each patient increased markedly within 24 h of the challenge test. Moreover, FA patients treated orally with SCG showed neither the increase in Copro-IgE levels nor any remarkable symptoms after the challenge. Our results suggest that the increased Copro-IgE levels may be a specific consequence of the local immune response to food allergen stimulation in the gut mucosa.

The Role of the Mast Cell in Clinical Gastrointestinal Disease with Special Reference to Systemic Mastocytosis

The gastrointestinal tract is a rich source of mast cells with an enormous surface area that permits a high degree of interaction between the mast cell and intestinal luminal contents. The active metabolic products of the mast cell influence gastrointestinal secretion, absorption, and motility through paracrine effects of local mast cell degranulation and also cause systemic effects through the release of cellular products into the blood stream. Systemic mastocytosis influences physiologic function through the systemic effects of mast cell products released from focal (e.g., bone marrow) or wide spread increases in mast cell number. Local gastrointestinal proliferation of mast cells in response to recognized (e.g., gluten in celiac sprue) or obscure stimuli can alter gastrointestinal function and induce systemic symptoms. Celiac sprue, inflammatory bowel disease, and non-ulcer dyspepsia are three examples of gastrointestinal diseases in which mast cells can be implicated in the pathophysiology of the symptoms.

Time-course studies of immediate and delayed immune reactivity in patients with atopic dermatitis treated with herbal drugs

We followed a number of in vitro parameters in nine adult patients with atopic dermatitis for a period of 3 weeks during which the patients took herbal drugs that are claimed to improve chronic eczema. The following investigations were performed weekly: blood leucocytes, circulating eosinophils, serum IgE, mitogen responsiveness of lymphocytes, interleukin 1 release, soluble interleukin 2 receptor levels in serum, and in vitro histamine release from basophils in blood. The study demonstrated increased levels of IgE in six patients, increased levels of soluble interleukin 2 receptor in six patients, and a significant correlation between the amount of IgE in serum and the maximal release of histamine from basophils in blood. In this open study five patients experienced a clinical worsening of their disease during the intake of herbal medicine. All other parameters were within normal levels. There was no significant change in the in vitro parameters during the observation period.