Hypersensitivity to ovalbumin induces chronic intestinal dysmotility and increases the number of intestinal mast cells

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.

Lipopolysaccharides facilitate colonic motor alterations associated to the sensitization to a luminal antigen in rats

Background/Aims

Enteric dysbiosis is a risk factor for dietary proteins-associated intestinal alterations, contributing to the development of food allergies and the symptomatology of functional gastrointestinal disorders, mainly irritable bowel syndrome (IBS). We explored if a dysbiotic-like state, simulated by intraperitoneal administration of bacterial lipopolysaccharides (LPS), facilitates the sensitization to a luminal antigen, ovalbumin (OVA), in rats.

Methods

Rats were exposed to oral OVA for 1 week, alone or with LPS. Thereafter, colonic histology, goblet cell density, mucosal eosinophils and mucosal mast cell (MMC) and connective tissue mast cell (CTMC) were evaluated. Colonic expression (real-time quantitative polymerase chain reaction) of interleukins, IFN-α1 and integrins was assessed to determine local immune responses. Luminal and wall adhered microbiota were characterized by fluorescence in situ hybridization. Colonic contractility (in vitro) served to assess functional changes associated to OVA and/or LPS.

Results

Neither OVA nor LPS, alone or combined, lead to structural alterations, except for a reduced goblet cell density in OVA-LPS-treated rats. MMC density was unaffected, while CTMC counts increased within the submucosa of OVA-LPS-treated animals. Marginal immune activation (IFN-α1 up-regulation) was observed in OVA-LPS-treated rats. LPS induced a dysbiotic-like state characterized by decreased luminal bacterial counts, with a specific loss of clostridia. LPS facilitated Clostridium spp. wall adherence, an effect prevented by OVA. Colonic contractility was altered in OVA-LPS-treated animals, showing increased basal activity and enhanced motor responses to OVA.

Conclusions

Changes in gut microbiota and/or direct effects of LPS might enhance/facilitate local neuroimmune responses to food antigens leading to motor alterations similar to those observed in IBS.

The controversial role of food allergy in infantile colic: evidence and clinical management

Food allergies (FAs) are an increasing problem in Western countries, affecting up to 10% of young children. FAs are frequently associated with gastrointestinal manifestations. The role of FAs as a potential causative factor for infantile colic (IC) is still controversial. We report the most recent evidence on the pathogenesis, clinical and diagnostic aspects of FA-induced infantile colic (IC) and suggest a stepwise diagnostic approach. We selected articles on clinical and immunologic features, pathogenesis and management of FAs and IC from of 1981 to 2015. Original and review articles were identified through selective searches performed on PubMed, using the following terms: colic, infantile colic, food allergy and infantile colic, infantile colic treatment. The possible relationship between FAs and IC derives from the presence of dysmotility with visceral hypersensitivity and dysbiosis, demonstrated in both conditions, and the clinical response to dietary interventions. Unfortunately, the design of the studies, poor characterization of atopy and different dietary approaches limit the understanding of the importance of FAs in subjects with IC. The role of FAs in IC subjects without other symptoms of atopy remains controversial. However, where there is a suspicion of FAs, a short trial with an extensively hydrolyzed cow's proteins formula or, if breast fed, with maternal elimination diet may be considered a reasonable option.

Motor activity as an unbiased variable to assess anaphylaxis in allergic rats

The release of mediators by mast cells triggers allergic symptoms involving various physiological systems and, in the most severe cases, the development of anaphylactic shock compromising mainly the nervous and cardiovascular systems. We aimed to establish variables to objectively study the anaphylactic response (AR) after an oral challenge in an allergy model. Brown Norway rats were immunized by intraperitoneal injection of ovalbumin with alum and toxin from Bordetella pertussis. Specific immunoglobulin (Ig) E antibodies were developed in immunized animals. Forty days after immunization, the rats were orally challenged with the allergen, and motor activity, body temperature and serum mast cell protease concentration were determined. The anaphylaxis induced a reduction in body temperature and a decrease in the number of animal movements, which was inversely correlated with serum mast cell protease release. In summary, motor activity is a reliable tool for assessing AR and also an unbiased method for screening new anti-allergic drugs.

Proinflammatory and anti-inflammatory cytokine profile in pediatric patients with irritable bowel syndrome

BACKGROUND AND OBJECTIVES

There is evidence that patients with irritable bowel syndrome (IBS) have a low degree of inflammation in the intestinal mucosa. The aim of the study was to evaluate the profile of pro- and anti-inflammatory cytokines in plasma in Mexican pediatric patients with IBS.

PATIENTS AND METHODS

Fifteen patients with IBS according to Rome III criteria for childhood and 15 healthy children, matched by age and sex, were included in the study. Plasma levels of tumoral necrosis factor alpha (TNF-α), interleukins 10 and 12 (IL-10, IL-12) and transforming growth factor beta (TGF-β) were quantified and compared between groups.

RESULTS

Plasma levels of IL-10 were lower in patients with IBS (86.07+21.3 pg/mL vs. 118.71+58.62 pg/mL: P=.045) and IL-12 levels were higher in patients with IBS compared to the control group of healthy children (1,204.2±585.9 pg/mL vs. 655.04±557.80 pg/mL; P=.011). The IL-10/IL-12 index was lower in patients with IBS (0.097±0.07 vs. 0.295±0.336; P=.025). Plasma concentration of TGF-β was higher in patients with IBS (545.67±337.69 pg/mL vs. 208.48±142.21 pg/mL; P=.001). There was no difference in plasma levels of TNF-α between groups.

CONCLUSIONS

This study suggests that children with IBS have a state of altered immune regulation. This is consistent with the theory of low-grade inflammatory state in these patients. Further studies are needed to elucidate the role played by these cytokines, specifically TGF-β in the pathogenesis of IBS.

Intraepithelial lymphocyte eotaxin-2 expression and perineural mast cell degranulation differentiate allergic/eosinophilic colitis from classic IBD

OBJECTIVES

Allergic colitis shows overlap with classic inflammatory bowel disease (IBD). Clinically, allergic colitis is associated with dysmotility and abdominal pain, and mucosal eosinophilia is characteristic. We thus aimed to characterise mucosal changes in children with allergic colitis compared with normal tissue and classic IBD, focusing on potential interaction between eosinophils and mast cells with enteric neurones.

METHODS

A total of 15 children with allergic colitis, 10 with Crohn disease (CD), 10 with ulcerative colitis (UC), and 10 histologically normal controls were studied. Mucosal biopsies were stained for CD3 T cells, Ki-67, eotaxin-1, and eotaxin-2. Eotaxin-2, IgE, and tryptase were localised compared with mucosal nerves, using neuronal markers neurofilament protein, neuron-specific enolase, and nerve growth factor receptor.

RESULTS

Overall inflammation was greater in patients with CD and UC than in patients with allergic colitis. CD3 T-cell density was increased in patients with allergic colitis, similar to that in patients with CD but lower than in patients with UC, whereas eosinophil density was higher than in all other groups. Eotaxin-1 and -2 were localised to basolateral crypt epithelium in all specimens, with eotaxin-1+ lamina propria cells found in all of the colitis groups. Eotaxin-2+ intraepithelial lymphocyte (IEL) density was significantly higher in allergic colitis specimens than in all other groups. Mast cell degranulation was strikingly increased in patients with allergic colitis (12/15) compared with that in patients with UC (1/10) and CD (0/1). Tryptase and IgE colocalised on enteric neurons in patients with allergic colitis but rarely in patients with IBD.

CONCLUSIONS

Eotaxin-2+ IELs may contribute to the periepithelial eosinophil accumulation characteristic of allergic colitis. The colocalisation of IgE and tryptase with mucosal enteric nerves is likely to promote the dysmotility and visceral hyperalgesia classically seen in allergic gastrointestinal inflammation.

NGF is involved in oral ovalbumin-induced altered colonic contractility in rats: evidence from the blockade of TrkA receptors with K252a

BACKGROUND

Nerve growth factor (NGF)-mucosal mast cell (MMC) interaction has been implicated in the remodeling of enteric circuitries and associated functional changes. We investigated the involvement of NGF and its receptor TrkA in the altered colonic contractile activity observed in the model of oral ovalbumin (OVA)-induced MMC hyperactivity in rats. We also studied the role of colonic MMCs as a source of NGF.

METHODS

Rats received oral OVA, alone or with the TrkA antagonist K252a. Colonic co-expression of NGF/TrkA and rat mast cell protease II (RMCPII) (double immunofluorescence), RMCPII content (ELISA) and expression of NGF, Brain-derived neurotrophic factor (BDNF) and TrkA/B (QT-PCR) were assessed. Colonic contractile activity was determined in vivo and in vitro.

KEY RESULTS

TrkA, but not NGF, was localized in colonic MMCs (RMCPII-positive). Oral ovalbumin exposure increased colonic RMCPII levels but did not change the percentage of TrkA-positive MMCs. Neither OVA nor K252a, alone or combined, altered NGF, BDNF or TrkA/B expression. Spontaneous colonic activity in vivo and in vitro was altered by OVA, an effect prevented by K252a. Electrical stimulation-induced contractile responses in vivo and carbachol responses in vitro were increased by OVA in a K252a-independent manner. In OVA-treated animals, inhibition of NO synthesis with l-NNA significantly enhanced spontaneous colonic activity in vitro, a response completely prevented by K252a.

CONCLUSIONS & INFERENCES

These results suggest that NGF-TrkA-dependent pathways are implicated in colonic contractile alterations observed during OVA exposure in rats. NGF-TrkA system might represent a potential target for treatment of gastrointestinal disorders characterized by colonic motor alterations.

Role of parasympathetic nerves and muscarinic receptors in allergy and asthma

Parasympathetic nerves control the symptoms and inflammation of allergic diseases primarily by signaling through peripheral muscarinic receptors. Parasympathetic signaling targets classic effector tissues such as airway smooth muscle and secretory glands and mediates acute symptoms of allergic disease such as airway narrowing and increased mucus secretion. In addition, parasympathetic signaling modulates inflammatory cells and non-neuronal resident cell types such as fibroblasts and smooth muscle contributing to chronic allergic inflammation and tissue remodeling. Importantly, muscarinic antagonists are experiencing a rebirth for the treatment of asthma and may be useful for treating other allergic diseases.

Persistent epithelial barrier alterations in a rat model of postinfectious gut dysfunction

BACKGROUND

Mucosal mast cells (MMCs), epithelial barrier function (EBF) and the enteric nervous system (ENS) are interactive factors in the pathophysiology of functional gastrointestinal disorders. We characterized postinfectious EBF alterations in the Trichinella spiralis infection model of MMC-dependent intestinal dysfunction in rats.

METHODS

Sprague-Dawley rats were infected with T. spiralis. 30 ± 2 days postinfection, jejunal EBF (electrophysiological parameters, fluorescein isothiocyanate-dextran fluxes and responses to secretagogues and MMC degranulators) was evaluated (Ussing chamber). In some experiments, participation of secretomotor neurons was examined by tetrodotoxin (TTX) pretreatment. Jejunal histology and MMC count and activity were also assessed.

KEY RESULTS

30 ± 2 days postinfection, when only a low grade inflammation was observed, increased MMC number and activity were associated with altered EBF. EBF alterations were characterized by increased mucosal permeability and ion secretion. In T. spiralis-infected animals, secretory responses to serotonin (5-HT) and immunoglobulin E (IgE)-dependent activation of MMCs were reduced. In contrast, responses to substance P (SP) and capsaicin were similar in infected and noninfected animals. Neuronal blockade with TTX altered secretory responses to SP and capsaicin only in infected rats.

CONCLUSIONS & INFERENCES

Trichinella spiralis infection in rats, at late stages, results in persistent postinfectious intestinal barrier dysfunctions and mucosal mastocytosis, with other signs suggestive of a low grade inflammation. The altered permeability and the TTX-independent hyporesponsiveness to 5-HT and IgE indicate epithelial alterations. Changes in responses to SP and capsaicin after neuronal blockade suggest an ENS remodeling during this phase. Similar long-lasting neuro-epithelial alterations might contribute to the pathophysiology of functional and postinfectious gastrointestinal disorders.

Anorectal function and visceral hypersensitivity in celiac disease

OBJECTIVE

To evaluate anorectal function and rectal sensitivity thresholds in patients with celiac disease (CD).

METHODS

In 25 unselected patients with CD (16 female, 9 male; mean age 45, range 24 to 75 y) and 20 controls (12 female, 8 male; mean age 41, range 20 to 65 y) anorectal manometry and rectal balloon distension test were conducted using a 4 lumen water perfused catheter with a polyethylene balloon (Zinectics Manometric Catheter, Medtronic).

RESULTS

In celiac patients the maximal anal resting pressure, reflecting the internal anal sphincter function, was significantly higher than that in the controls: 87.8±21.7 mm Hg versus 66.7±15.2 mm Hg (P<0.001). There were no considerable differences between both the groups neither in the maximal anal squeeze nor in the cough pressures. Celiac patients had significantly lower first sensation threshold: 25.6±10.8 mL versus 37.5±12.5 mL (P<0.05). Visceral hypersensitivity (rectal pain/discomfort threshold ≤100 mL) was observed in 36% of celiac patients and in none of the controls (P<0.01).

CONCLUSIONS

The increased anal resting pressure and rectal hypersensitivity are observed in CD. Disturbances in gastrointestinal motility and visceral perception in the course of CD may occur at different levels of the brain-gut axis including direct changes in the enteric nervous system.

Mucosal mast cells mediate motor response induced by chronic oral exposure to ovalbumin in the rat gastrointestinal tract

We previously demonstrated that oral chronic exposure to ovalbumin (OVA) causes intestinal hypermotility in Sprague-Dawley rats. In this study, the objective was to determine the mechanism of action of OVA and the role of mucosal mast cells in the regulation of motor activity in this model. Rats were orally exposed to OVA during 6 weeks. Intestinal mucosal mast cells (IMMCs) were counted and rat mast cell protease II (RMCPII) measured in duodenum, jejunum, ileum and colon. Anti-OVA IgE, IgG, and IL-4 were measured in serum. Eosinophils and IgE(+) cells were counted in jejunum. In an additional study rats were treated with the mast cell stabilizer ketotifen and mast cell number, RMCPII concentration and motor activity in vitro were evaluated. OVA exposed rats showed an increase in mucosal mast cell number and in RMCPII content in small intestine and colon. However, variables of a Th(2) type response were not affected by exposure to OVA: (i) neither OVA specific IgE nor IgG were found; (ii) IL-4 did not increase and, (iii) the number of eosinophils and IgE(+) cells was identical in the exposed and unexposed groups. These results brought us to hypothesize a possible non-Ig-mediated action of OVA on mast cells. Ketotifen significantly diminished the response to OVA: Ketotifen reduced the number of mast cells and the RMCPII content and blocked increased intestinal contractility. In addition ketotifen modified motor response in both OVA exposed and unexposed animals giving evidence of the importance of mast cells in intestine motor activity driving.

Duodenal mastocytosis, eosinophilia and intraepithelial lymphocytosis as possible disease markers in the irritable bowel syndrome and functional dyspepsia

BACKGROUND

Irritable bowel syndrome (IBS) and functional dyspepsia (FD) are common functional disorders without defined pathology. Mast cells and eosinophils interact with T lymphocytes and may alter enteric nerve and smooth muscle function.

AIM

To examine mast cell, eosinophil and intraepithelial lymphocyte populations in duodenal biopsies of subjects with IBS and FD.

METHODS

A random sample of an adult Swedish population (n = 1001; mean age 54 years; 51% female) underwent upper endoscopy and biopsy; 51 cases with FD and 41 cases with IBS were compared with 48 randomly selected controls. Eosinophils were identified by light microscopy; mast cells by immunocytochemistry (CD117). Intraepithelial lymphocytes were counted per 100 enterocytes. Cell counts were quantified by counting the number per high power field (HPF) in 5HPFs in the bulb (D1) and second part of duodenum (D2), summed over 5HPFs at each site.

RESULTS

Cases and controls showed similar demographics. Compared to controls, IELs in IBS-constipation were significantly increased (P = 0.005). Mast cells were significantly increased in IBS in D2 (P < 0.001), while eosinophils were significantly increased in FD in D1 and D2 (P < 0.001).

CONCLUSION

Duodenal mast cell hyperplasia is linked to IBS and eosinophilia to FD, and duodenal biopsy may identify subsets of these disorders.

Neuroimmune interaction and anorectal motility in children with food allergy-related chronic constipation

OBJECTIVES

Food allergy is thought to trigger functional constipation in children but the underlying mechanisms are still unknown. Mast cells (MCs) and their relationship with nerve fibers (NFs) in the rectal mucosa, as well as anorectal motility, were studied in children with refractory chronic constipation before and after an elimination diet for cow's milk, egg, and soy proteins.

METHODS

Thirty-three children (range: 1-10.8 years) underwent anorectal manometry and suction rectal biopsy before and after 8 weeks of oligoantigenic diet. MCs and NFs were identified immunohistochemically. Quantification of MCs (%MC/area) and MCs within 10 microm of NFs (%MC-NF/area) was performed by computer-assisted analysis.

RESULTS

Eighteen children responded to the diet (R-group) and fifteen did not (the NR-group). At baseline there was a significant difference in anal resting pressure (ARP; mm Hg), percentage of relaxation (%R), and residual pressure (RP; mm Hg) of anal canal during rectal distension between the R-group (66+/-4.1, 84.3+/-2.8, 10.4+/-2.3, respectively) and the NR-group (49+/-5, 92.2+/-1.7, 4.8+/-1.7, respectively; P<0.05). After the diet, significant changes in ARP, RP, and %R were observed only in the R-group (44+/-3.7, 93.7+/-1.5, 3.8+/-1.2, respectively; P<0.05). At baseline, the R-group showed an increase in %MC/area (8.3+/-0.7) and %MC-NF/area (5.2+/-2.6) with respect to the NR-group (5.1+/-0.5 and 2.3+/-0.4, respectively; P<0.05). After the diet, only the R-group showed a significant reduction of %MC/area and %MC-NF/area (4.4+/-0.5 and 2.2+/-0.4, respectively; P<0.001). Both ARP and RP significantly correlated with %MC/area and %MC-NF/area; %R showed a significant inverse correlation with both %MC/area and %MC-NF/area.

CONCLUSIONS

In children with food allergy-related chronic constipation, an increase in both rectal MC density and spatial interactions between MCs and NFs correlates with anal motor abnormalities. These variables are significantly affected by the diet.

Mast cell-nerve interactions in children with functional dyspepsia

BACKGROUND AND AIMS

Functional dyspepsia in childhood is commonly triggered by food allergen in sensitised individuals. We investigated the topography of eosinophils and mast cells in gastric antral lamina propria, the interaction of mast cell products with mucosal nerve fibres, and changes in gastric antral muscle slow wave activity in children with atopy and non-atopy-related functional dyspepsia.

PATIENTS AND METHODS

Open label study of gastric mucosal cow's milk challenge in 10 atopic and 6 nonatopic children (ages 2-12 years) investigated consecutively with gastroscopy for functional dyspepsia. Simultaneous surface electrogastrography and milk challenge were undertaken and laser scanning fluorescence microscopy used to examine the association of mast cell tryptase with mucosal nerves in the gastric mucosa before and after challenge.

RESULTS

Eosinophils and mast cells within the lamina propria were increased in number in children with atopic functional dyspepsia and degranulated rapidly after cow's milk challenge in the atopic group. For degranulating eosinophils, median = 13.0% (interquartile range = 3.7-31.0) premilk versus 32.0% (12.0-42.0) after milk biopsies (P < 0.05); for degranulating mast cells, 5.35% (2.7-10.9) premilk biopsies versus 18.75% (12.9-22.1) after milk biopsies (P < 0.05). No such differences were seen in nonatopic patients. Mast cells were closely associated with mucosal nerve fibres and released tryptase, which colocalised with proteinase-activated receptors on mucosal nerve fibres. The gastric antral slow wave became abnormal within 2 minutes of antigen challenge in atopics with an increase in dominant frequency instability coefficient (P < 0.005), decrease in 3 cycles per minute myoelectrical activity (P < 0.01), and increase in bradygastria (P < 0.01).

CONCLUSIONS

Early-onset neuroimmune interactions induced by cow's milk in the gastric mucosa of atopic children are associated with rapid disturbance of gastric myoelectrical activity and dyspeptic symptoms.

Allergy and intestinal dysmotility--evidence of genuine causal linkage?

PURPOSE OF REVIEW

The relationship between allergy and motility has been controversial. There is, however, accumulating evidence demonstrating that mucosal allergic responses may disrupt gut motility, and may also potentially alter nociceptive pathways to cause visceral hyperalgesia.

RECENT FINDINGS

Experimental studies implicate T helper 2 cells and the cytokines interleukin-4 and -13 in antigen-induced dysmotility, and interleukin-5 in the pathogenesis of mucosal eosinophilia. Both mast cells and eosinophils play obligatory roles in different forms of experimental antigen-induced dysmotility. Overall clinical findings appear to implicate eosinophil infiltration in proximal and distal dysmotility syndromes (oesophageal, gastric and colorectal), and induced mast cell degranulation in mid-gut dysmotility. There is also evidence that mucosal allergic responses may induce long-term changes in visceral perception, including alteration of limbic response, leading to sustained abnormality in visceral sensation.

SUMMARY

Clinical evidence implicating mucosal allergic responses in dysmotility has been extended to include disorders considered previously entirely functional, such as in some cases of irritable bowel syndrome. Only a proportion of cases are, however, caused by food allergy and a future challenge is to differentiate patients with similar symptoms, but induced by different mechanisms.

Mast cell stabilizer ketotifen [4-(1-methyl-4-piperidylidene)-4h-benzo[4,5]cyclohepta[1,2-b]thiophen-10(9H)-one fumarate] prevents mucosal mast cell hyperplasia and intestinal dysmotility in experimental Trichinella spiralis inflammation in the rat

Trichinella spiralis infection in rats induces hypermotility and an abnormal response to cholecystokinin (CCK) similar to motor disturbances observed in irritable bowel syndrome. Mast cell hyperplasia is also characteristic of this experimental model. The aim of our study was to correlate mast cell activity with the development of dysmotility and to demonstrate whether the mast cell stabilizer ketotifen [4-(1-methyl-4-piperidylidene)-4H-benzo[4,5]cyclohepta[1,2-b]thiophen-10(9H)-one fumarate] could prevent the development of intestine hypermotility. Sprague-Dawley rats were infected with T. spiralis and, 5 days after infection, treated with the mast-cell stabilizer ketotifen (10 mg/kg/day). Twelve days after infection, intestinal spontaneous motor activity and response to CCK were evaluated by means of strain-gauge transducers. Immunohistochemistry for rat mast cell protease II (RMCPII), cyclooxygenase (COX)-2, and inducible nitric-oxide synthase (iNOS) was performed in intestinal specimens. In addition, RMCPII and myeloperoxidase were determined in serum. Infected control rats showed hypermotility, mast cell hyperplasia, increased RMCPII levels, increased myeloperoxidase, and overexpression of COX-2 and iNOS. In contrast, ketotifen-treated rats showed spontaneous intestinal motility and CCK response similar to the noninfected control rats. Mast cell hyperplasia and RMCPII were reduced in ketotifen-treated rats. Inflammatory parameters were less modified by ketotifen, but those animals that received the longest ketotifen treatment showed a slight amelioration in these parameters. These results indicate that mast cells are implicated in the development of hypermotility. The treatment with ketotifen prevented hypermotility and mast cell hyperplasia and diminished mucosal mast cell activity.

Food allergy and irritable bowel syndrome

PURPOSE OF REVIEW

Irritable bowel syndrome is a common and likely a multifactorial gastrointestinal disorder in which a disturbed brain-gut axis has been thought to have a mandatory role. Recent clinical and experimental studies imply that dietary factors may be more important in the pathogenesis of irritable bowel syndrome than was earlier anticipated. The purpose of this review is to present those studies and discuss their findings in relation to the crosstalk between the gastrointestinal immune and nervous systems.

RECENT FINDINGS

Food elimination based on serum immunoglobulin G antibodies in irritable bowel syndrome has been found to result in a significant decrease in symptoms, compared with diets in which dietary restrictions are not guided by those antibodies. Both numbers of mast cells and their mediators have been shown to be increased in intestinal mucosa in patients with irritable bowel syndrome, especially in the close proximity of intestinal nerves. Animal studies have demonstrated that this increase in intestinal mast cell density could be a consequence of local hypersensitivity to food antigens. That kind of local gastrointestinal hypersensitivity seems to be beyond the reach of current diagnostic methods available in clinical practice.

SUMMARY

Dietary factors may significantly contribute to the pathophysiology of irritable bowel syndrome. Elimination diets based on the detection of local food hypersensitivity may offer a treatment option for irritable bowel syndrome patients in the future.