Evaluation of mucosal eosinophils in the pediatric colon

Diagnostic Utility of Mucosal Biopsies Taken During Colonoscopy-Guided Colonic Manometry Catheter Placement

OBJECTIVES

The diagnostic utility of mucosal biopsies taken during colonoscopy-guided colonic manometry catheter placement is unknown. The aims of our study were to determine the frequency and histopathology results of mucosal biopsies during these procedures and to assess whether there were any associations between the histology or gross findings with manometry results.

METHODS

We performed a retrospective chart review of children who had a colonic manometry study completed between 2008 and 2020 at a quaternary children's hospital. We captured patient demographics, biopsy locations, histopathology results, gross endoscopy findings, and manometry results. The chi-squared test and when appropriate Fisher exact test was used to evaluate categorical associations.

RESULTS

One hundred forty-eight patients were included. One hundred eighteen (80%) had colonic biopsy and 63 (43%) had ileal biopsy. Colonic histology findings, which patients could have multiple, included lymphonodular hyperplasia (34%), normal (27%), chronic inflammation (24%), melanosis coli (21%), colonic eosinophilia (10%), and acute inflammation (8%). Ileal histology findings included increased Peyer patches (44%), normal (44%), acute inflammation (11%), chronic inflammation (3%), eosinophilia (5%), and eosinophilic ileitis (3%). The majority of acute and chronic inflammation was graded as mild. There were no statistically significant associations of histology to gross endoscopy or manometry findings.

CONCLUSIONS

Colonic biopsies are obtained in the majority of patients presenting for colonic manometry evaluation with ileal biopsies obtained less frequently. Histopathology findings are noted frequently, but the majority are the result of or did not impact clinical care. There were no associations between abnormal histopathology or abnormal gross endoscopy findings with colonic manometry results.

Colonic mucosal eosinophilia in children without inflammatory bowel disease

Children undergoing colonoscopy and mucosal biopsies may show increased colonic mucosal eosinophils, which may or may not be associated with inflammatory bowel disease. There is not much clinical data on American children who have isolated increased colonic mucosal eosinophils. We sought to study the clinical correlates of children without inflammatory bowel disease who show increased mucosal eosinophils to understand their clinical presentation, etiological associations, and outcome. A retrospective analysis of children seen at a tertiary-level Children's hospital was performed by reviewing their medical charts and extracting pertinent data. There were 110 children in the study who had increased colonic mucosal eosinophils. Most children presented with abdominal pain, but several of them also had constipation, blood in stools, and diarrhea. Food allergies, irritable bowel syndrome, asthma, and lactase deficiency were the top four conditions present in these patients. Pathology of the colonic distribution revealed involvement of more than two colonic regions in 86% of the subjects, and only two subjects showing epithelial or crypt involvement by eosinophils. All subjects had a good outcome. Children with colonic mucosal eosinophilia (CME) who do not have an inflammatory bowel disease most frequently present with abdominal pain and primarily an increase of lamina propria eosinophils in two or more colonic regions. Based on the etiological associations we noted in the study, a work-up of children with CME may encompass detailed history for functional gastrointestinal disorders and lactose intolerance, testing for food and environmental allergies, stool examination for parasites, and peripheral blood counts. Almost all children had resolution of symptoms in the studied period suggesting that CME in children has a good clinical outcome.

Non-IgE- or Mixed IgE/Non-IgE-Mediated Gastrointestinal Food Allergies in the First Years of Life: Old and New Tools for Diagnosis

non-IgE and mixed gastrointestinal food allergies present various specific, well-characterized clinical pictures such as food protein-induced allergic proctocolitis, food protein-induced enterocolitis and food protein-induced enteropathy syndrome as well as eosinophilic gastrointestinal disorders such as eosinophilic esophagitis, allergic eosinophilic gastroenteritis and eosinophilic colitis. The aim of this article is to provide an updated review of their different clinical presentations, to suggest a correct approach to their diagnosis and to discuss the usefulness of both old and new diagnostic tools, including fecal biomarkers, atopy patch tests, endoscopy, specific IgG and IgG4 testing, allergen-specific lymphocyte stimulation test (ALST) and clinical score (CoMiss).

Cow's Milk Protein Allergy in Infancy: A Risk Factor for Functional Gastrointestinal Disorders in Children?

The role and prevalence of cow's milk protein allergy (CMA) in functional gastrointestinal disorders remains unclear. The aim of this review is to update knowledge on the relationship between CMA and functional abdominal pain disorders (FAPDs) in children. Cochrane Database and Pubmed were searched from inception using general and specific terms for CMA and functional gastrointestinal disorders. CMA is reported as a predisposing or coexisting factor in a wide range of functional gastrointestinal disorders in infants and children. Pathogenesis of both conditions is complex and multiple mechanisms including dysmotility and hypersensitivity might contribute to the clinical manifestations. Data supporting the possible role of food allergies in the pathogenesis of FAPDs are limited. CMA may predispose to early life inflammation and visceral hypersensitivity, which in turn might manifest as FAPDs. The diagnosis of either CMA or FAPDs and distinction between them is challenging because of nonspecific and overlapping symptoms. Lack of accurate allergy tests in non-IgE (immunoglobulin E) mediated cases is also problematic. Oral food challenge, following an elimination diet, should be performed to diagnose a suspected non-IgE CMA allergy in children with FAPDs. In the management of FAPDs, an elimination diet should be considered for a limited period to verify if the symptoms improve or resolve.

Quantitative Analysis of Distribution of the Gastrointestinal Tract Eosinophils in Childhood Functional Abdominal Pain Disorders

Background/Aims

Although functional abdominal pain disorders (FAPDs) are common in children, the accurate pathogenesis of FAPDs is not known yet. Micro-inflammation, particularly tissue eosinophilia of gastrointestinal (GI) tract, has been suggested as the pathophysiology observed in several GI disorders. We aimed to evaluate eosinophilic infiltration throughout the entire GI tract in children with FAPDs, compared to those with inflammatory bowel diseases (IBD) and to normal reference values.

Methods

We included 56 children with FAPDs, 52 children with Crohn's disease, and 23 children with ulcerative colitis. All subjects underwent esophagogastroduodenoscopic and colonoscopic examination with biopsies. Tissue eosinophil counts were assessed in 10 regions throughout the GI tract.

Results

Eosinophil counts of the gastric antrum, duodenum, terminal ileum, cecum, and ascending colon were significantly higher in children with FAPDs compared to normal reference values. Eosinophil counts of the stomach and the entire colon were observed to be significantly higher in children with IBD than in those with FAPDs. Even after selecting macroscopically uninvolved GI segments on endoscopy in children with IBD, eosinophil counts of the gastric body, cecum, descending colon, sigmoid colon, and the rectum were also significantly higher in children with IBD than those with FAPDs.

Conclusions

Significantly high eosinophil counts of the stomach and colon were observed in the order of IBD, followed by FAPDs, and normal controls, regardless of endoscopically detected macroscopic IBD lesions in children. This suggests some contribution of GI tract eosinophils in the intrinsic pathogenesis of FAPDs in children.

Nonesophageal Eosinophilic Gastrointestinal Disorders: Clinical Care and Future Directions

Eosinophilic gastrointestinal disorders are a set of conditions with a wide range of clinical manifestations and treatment modalities. The disorders are suspected to result from an abnormal inflammatory response to allergen (s), and individuals may develop a relapsing or chronic disease, if the allergen is not eliminated. Mechanisms of disease pathogenesis, including the humoral immune response, need to be fully elucidated. A variety of therapies are used, although there is a lack of well-defined randomized, prospective studies. Other therapeutic options are needed as the current treatments have potential concerns; elimination diets may impair a child's quality of life, and corticosteroids have adverse risks with long-term use. We review what is known about nonesophageal eosinophilic gastrointestinal disorders, and discuss research investigations which need to be conducted to facilitate diagnosis and enhance treatment methods.

Clinical Implications of Pediatric Colonic Eosinophilia

OBJECTIVE

Pediatric colonic eosinophilia represents a confounding finding with a wide differential. It is often difficult to determine which children may progress to inflammatory bowel disease (IBD), which have an eosinophilic colitis (EC), and which may have no underlying pathology. There is little guidance for the practitioner on the approach to these patients. To define the clinical presentations of colonic eosinophilia and identify factors which may aid in diagnosis we reviewed patients with colonic eosinophilia and the clinicopathologic factors associated with their diagnoses.

METHODS

An 8-year retrospective chart review of children whose histopathology identified colonic eosinophilia (N = 72) compared to controls with normal biopsies (N = 35).

RESULTS

Patients with colonic eosinophilia had increased eosinophils/high-power field compared to controls (P < 0.001) and had 3 clinical phenotypes. Thirty-six percent had an inflammatory phenotype with elevated erythrocyte sedimentation rate (P < .0001), chronic inflammation on colonic biopsies (P < 0.001), and were diagnosed as having IBD. Thirty-seven percent were diagnosed as having EC, associated with male sex (P < 0.005) and peripheral eosinophilia (P = 0.041). Twenty-one percent had no significant colonic pathology. Forty-three percent of patients had >1 colonoscopy and 68% of these had change from initial diagnoses.

CONCLUSIONS

There are 3 main phenotypes of children with colonic eosinophilia. Signs of chronic systemic inflammation raise suspicion for IBD. Peripheral eosinophilia and male sex are associated with EC. A significant percent of children with colonic eosinophilia do not have colonic disease. Eosinophils/high-power field is not reliable to differentiate etiologies. Repeat colonoscopies may be required to reach final diagnoses.

Eosinophilic Gastrointestinal Disorders Pathology

Eosinophilic gastrointestinal disorders (EGID) are characterized pathologically by excess eosinophils in mucosal biopsies of one or multiple sites in the gastrointestinal (GI) tract, simultaneously or sequentially. Eosinophilic esophagitis (EoE) is the best characterized EGID, and in most patients it is an abnormal immune-mediated response to food antigens. Current recommendations for diagnosis include signs and symptoms of esophageal dysfunction that do not respond to proton-pump inhibitor therapy, and esophageal biopsies that exhibit at least 15 intraepithelial eosinophils in at least one high power field (HPF). Therapy consists of swallowed glucocorticoids or dietary elimination. Eosinophilic gastritis (EG) is the second most common form of EGID, but like all forms of EGID except EoE consensus recommendations for either clinical or pathological diagnosis do not exist. EG may be associated clinically with peripheral blood eosinophilia, hypoalbuminemia, and anemia, and pathologically with marked expansion of lamina propria by dense eosinophilic infiltrates. Eosinophilic enteritis (EE) may be subdivided into eosinophilic duodenitis, eosinophilic jejunitis, and eosinophilic ileitis. Most investigators believe that EE rarely, if ever, exists as a solitary form of EGID and is encountered only in patients who have at least one other affected portion of the GI tract. Eosinophilic colitis (EC) is perhaps the most enigmatic EGID. Distinction of EC from inflammatory bowel disease may be problematic especially in children. Multiple possible etiologies for EGID include hypereosinophilic syndrome, drug reactions, etc. Currently, the only etiology that can be identified histologically is parasitic infestation, if a portion of an invasive parasite is found in mucosal biopsies. This review will provide guidelines for the pathologic diagnosis of the various forms of EGID.

Histologic Correlates of Clinical and Endoscopic Severity in Children Newly Diagnosed With Ulcerative Colitis

To characterize rectal histology in an inception cohort of children newly diagnosed with ulcerative colitis (UC) and to explore its relationship with clinical indices of disease severity. The PROTECT (Predicting Response to Standardized Pediatric Colitis Therapy) Study enrolled children 17 years of age and younger newly diagnosed with UC. Baseline rectal biopsies were evaluated for acute and chronic inflammation, eosinophilic inflammation (peak eosinophil count > 32 eosinophils/high powered field, eosinophilic cryptitis or abscesses), and architectural/nonarchitectural chronic changes. Correlation with clinical indices including Mayo endoscopy subscore and Pediatric Ulcerative Colitis Activity Index was performed. Rectal biopsies from 369 patients (mean age, 12.9±3.1 y, 50% female) were reviewed. Cryptitis was found in 89%, crypt abscesses in 25%, and eosinophilic inflammation in 58%. Crypt distortion/atrophy was present in 98% of specimens. Higher grades of acute and chronic inflammation were associated with the presence of basal plasmacytosis (P<0.0001), basal lymphoid aggregates (P<0.0001), and surface villiform changes (P<0.0001). A severe Mayo endoscopy subscore was most common among those with severe acute and chronic inflammation, although this relationship was not linear. Severe Pediatric Ulcerative Colitis Activity Index scores were associated with the absence of or only mild eosinophilic inflammation (<32 eosinophils/high powered field) (P<0.03) and the presence of surface villiform changes (P<0.005). Acute and chronic inflammation, eosinophilic inflammation and chronic changes are common in children newly diagnosed with UC. The clinical and biological implication of low to absent eosinophilic inflammation and the presence of surface villiform changes requires further study.

Eosinophilic colitis in children

INTRODUCTION

Eosinophilic colitis, which is a rare form of eosinophilic gastrointestinal diseases, occurs as primary and secondary allergic eosinophilic colitis of the gastrointestinal tract infection, inflammatory bowel disease, celiac disease, and vasculitis. The diagnosis is based on a significant amount of eosinophils in the inflammatory infiltrate of the colon wall.

AIM

To analyze the clinical picture taking into account comorbidities and endoscopic picture in children with eosinophilic colitis.

MATERIAL AND METHODS

The test group consisted of 43 children, the average age - 12.1 years diagnosed with eosinophilic colitis (according to the Whitington scale) hospitalized in the Gastroenterology Unit, Department of Pediatrics of the Medical University of Silesia in Katowice. Testing for food allergies, celiac disease, inflammatory bowel disease, gastrointestinal diseases and parasitic diseases was performed in the group of children and the analysis concerned the intensity of eosinophilic infiltration of the colon mucosa with the severity of clinical symptoms, endoscopic picture, the presence of inflammatory bowel disease, and food allergy.

RESULTS

Half of the tested children suffered from isolated eosinophilic colitis but the rest of them had eosinophilic infiltrate with inflammatory bowel disease more often, however, the Crohn's disease. The endoscopic image was uncharacteristic, and grade III in the Whitington scale was predominant in the histopathological examination, in most cases located in the entire large intestine. The higher level of total IgE was found in less than half of the patients and it did not correlate with the severity of eosinophilic infiltration. It was shown that the severity of eosinophilic infiltration correlated with exacerbation of clinical symptoms, endoscopic image, and the presence of inflammatory bowel disease. The higher level of antibodies of ASCA and ANCA was found in approximately 20% of the children with isolated eosinophilic colitis and 63% of children with Crohn's disease.

CONCLUSIONS

The higher concentration of total IgE in less than half of the patients with eosinophilic colitis indicates the need for improving allergy diagnosis also in terms of IgE-independent allergy. The presence of higher levels of antibodies of ASCA and ANCA in some of the patients with isolated eosinophilic colitis indicates the need for further observation for the occurrence of inflammatory bowel disease.

Quantitative evaluation of duodenal eosinophils and mast cells in adult patients with functional dyspepsia

The role of duodenal eosinophils and mast cells (MCs) in the pathogenesis of functional dyspepsia (FD) remains poorly understood. This study aimed to examine the counts and degranulation of duodenal eosinophils and MCs in FD patients to explore the association between FD and both cell types. We recruited 141 FD patients and 39 healthy controls for this study. Biopsy specimens were collected from the duodenal bulb (D1) and the descending part (D2) of the duodenum of all participants. Eosinophil counts and degranulation, and MC counts and degranulation at both sites were quantitatively evaluated by hematoxylin and eosin staining, major basic protein immunostaining, and toluidine blue staining, respectively. Receiver operating characteristic analysis was applied to evaluate the diagnostic accuracy of these parameters in identifying FD cases. We found that the eosinophil counts at D2 were considerably increased in FD patients compared with healthy controls, and that the proportion of cases with eosinophil degranulation at D2 was significantly higher in the FD group. In addition, FD patients showed significantly increased MC counts and degranulation both at D1 and D2, and receiver operating characteristic analysis further demonstrated that these parameters, in particular the degranulation of MCs, appear to be highly sensitive and specific for the identification of FD patients. Our findings suggest that the increased eosinophil counts and degranulation at D2, and the increased MC counts and degranulation at D1 and D2 may be the histologic markers of FD. MC degranulation at D1 and D2 appears to be highly sensitive and specific for FD identification.

Diagnosing eosinophilic colitis: histopathological pattern or nosological entity?

Reports of  "eosinophilic colitis"-raised colonic mucosal eosinophil density in patients with lower gastrointestinal symptoms-have increased markedly over the last fifteen years, though it remains a rarity. There is no consensus over its diagnosis and management, and uncertainty is compounded by the use of the same term to describe an idiopathic increase in colonic eosinophils and an eosinophilic inflammatory reaction to known aetiological agents such as parasites or drugs. In patients with histologically proven colonic eosinophilia, it is important to seek out underlying causes and careful clinicopathological correlation is advised. Because of the variability of eosinophil density in the normal colon, it is recommended that histological reports of colonic eosinophilia include a quantitative morphometric assessment of eosinophil density, preferably across several sites. Few reported cases of "eosinophilic colitis" meet these criteria. As no correlation has been shown between colonic eosinophil density and symptoms in older children or adults, it is suggested that treatment should be directed towards alleviation of symptoms and response to treatment assessed clinically rather than by histological estimates of intramucosal eosinophils.

Clinical significance of eosinophilia and chronic inflammatory infiltrate in children's rectal biopsies

AIMS

The aim of the present study was to determine the clinical significance of an incidental finding of eosinophilia (EOS) and chronic inflammatory infiltrate (CINF) in rectal biopsies of children investigated for suspected Hirschsprung disease (HSCR).

METHODS

A retrospective study (2000-2010) of children incidentally found to have EOS and CINF was performed. HSCR cases were excluded. Presence of gastrointestinal (GI) symptoms and nutritional status (weight-for-age z score) were investigated and compared with a matched cohort with normal biopsy.

RESULTS

Of 364 children undergoing rectal biopsy for suspected HSCR, 109 had confirmed HSCR, whereas 255 children had normal ganglia. Forty-four of 255 (17%) children had EOS and/or CINF incidentally reported and are the subject of the present study. In 13 of 44 (29%) children, the biopsy was performed neonatally. At follow-up (4.6 months [1-22]), 21 (48%) had food and/or milk allergy, 30 (68%) had constipation and/or other GI symptoms. There was no change in weight-for-age z score (P = 0.85) at follow-up and 8 (20%) had failure to thrive. Only 10 of 44 (P = 0.0001 vs patients with EOS and/or CINF) children with normal biopsy had persistent constipation at follow-up (9.7 months [0.5-84.7]) and 1 patient had atopy. Patients with normal biopsy exhibited an increase in weight-for-age z score at follow-up (P = 0.003) and only 3 patients (7%) had failure to thrive.

CONCLUSIONS

EOS and CINF are found in 17% of children who had rectal biopsies negative for HSCR. Half of these children will need further medical input for the presence of persisting GI symptoms, food/milk allergy and failure to thrive, and the possibility to develop inflammatory bowel disease later in life.

Update on clinical and immunological features of eosinophilic gastrointestinal diseases

PURPOSE OF REVIEW

Eosinophilic gastrointestinal diseases (EGIDs) are an increasingly common heterogeneous group of intestinal diseases. The purpose of this review is to present the latest developments in the care of patients with EGIDs and to summarize a growing literature defining the clinical features and mechanistic elements of eosinophils and their complex relationships with the gastrointestinal tract.

RECENT FINDINGS

Recent studies continue to define what constitutes 'normal' and 'abnormal' numbers of eosinophils in the different sections of the gastrointestinal tract. Symptom complexes of EGIDs appear to be related primarily to the mucosal, as opposed to the muscular or serosal, forms of EGIDs. Dissection of the mucosal microenvironment is uncovering a complex array of cells, other than eosinophils, that likely contribute to the inflammatory response associated with EGIDs. Mechanistic studies have identified genetic perturbations (eotaxin-3, thymic stromal lymphopoietin, IL-13, and filaggrin) that may also contribute to the development of the most often encountered and well studied EGID, eosinophilic esophagitis.

SUMMARY

Clinicians should remain aware of EGIDs as a diagnostic possibility for patients with common gastrointestinal symptoms. Additional research is needed to determine mechanistic processes leading to dysfunction associated with eosinophilic gastrointestinal inflammation.

Normal quantity and distribution of mast cells and eosinophils in the pediatric colon

The normal number and distribution of mast cells (MCs) and eosinophils in colonic mucosa are largely unknown. Accordingly, we examined colonic biopsies obtained during endoscopic examinations of pediatric patients. The study included 41 patients (21 males and 20 females). The mean age was 11.72 years (range 3.3-19.7 years). Patients were followed for a mean time of 23.4 months (range 12-50 months). Our results showed a gradual decrease in the number of eosinophils in the lamina propria from the cecum to the descending colon (14.2 ± 6.1 and 10.7 ± 5.6 eosinophils//high-power field [hpf], respectively), with another peak in the rectosigmoid (12.4 ± 6.1 eosinophils/hpf). Eosinophils within the surface and crypt epithelium were more commonly encountered in the cecum and the rectosigmoid. Eosinophils clusters were rare but were more frequently found in the cecum and rectosigmoid. The largest number of MCs was observed in the descending colon and the lowest in the rectosigmoid (17.56 ± 7.28 and 14.5 ± 6.35 MCs/hpf, respectively). No MCs were identified within the surface epithelium. Very rare MCs were observed within the crypt epithelium, with the highest number observed in the cecum (0.34 ± 0.53 MCs/hpf) and the lowest number observed in the descending colon (0.02 ± 0.16 MCs/hpf). More MCs were present in the cecum and descending colon of females vs males (P  =  0.02 and 0.04, respectively). Our results establish baseline gastrointestinal eosinophils and MC counts in various parts of the pediatric colon.

Role of eosinophils in inflammatory bowel and gastrointestinal diseases

Inflammatory bowel diseases (IBD) are characterized by the invasion of leukocytes into the intestinal mucosa. However, a mixed inflammatory picture is observed that includes neutrophils, lymphocytes, monocytes, and eosinophils. To this day, the role of eosinophils in health and in disease remains unclear. Investigations into their function stem primarily from allergic diseases, asthma, and parasitic infections. This makes it even more difficult to discern a role for the fascinating eosinophil in IBDs because, unlike the lung or the skin, eosinophils reside in normal intestinal mucosa and increase in disease states; consequently, an intricate system must regulate their migration and numbers. These granulocytes are equipped with the machinery to participate in gastrointestinal (GI) inflammation and in the susceptible microenvironment, they may initiate or perpetuate an inflammatory response. A significant body of literature characterizes eosinophils present in the GI microenvironment where they have the potential to interact with other resident cells, thus promoting intestinal remodeling, mucus production, epithelial barrier, cytokine production, angiogenesis, and neuropeptide release. A number of lines of evidence support both potential beneficial and deleterious roles of eosinophils in the gut. Although studies from the gut and other mucosal organs suggest eosinophils affect mucosal GI inflammation, definitive roles for eosinophils in IBDs await discovery.

Clinicopathological significance of eosinophil granulocyte infiltration in the intestinal mucosa of patients with ulcerative colitis

AIM: To examine eosinophil granulocyte (EG) infiltration in the intestinal mucosa of patients with ulcerative colitis (UC) and analyze the correlation of EG infiltration with clinical activity index (CAI), endoscope activity index (EAI) and histopathological parameters of the disease.

METHODS: Forty-five UC patients treated at our hospital from November 2007 to December 2008 were divided into two groups according to disease activity: active group (n = 45) and remission group (n = 39, patients achieving complete and partial remission after treatment for 6 weeks or more during entire treatment course). CAI, EAI and histopathological parameters were used to evaluate disease activity. The number of EGs was counted.

RESULTS: The intestinal mucosa of UC patients was infiltrated mainly by neutrophils, lymphocytes, plasmatocytes and EGs. The inflammatory infiltration was more severe in the active group than in the remission group. Pathological changes in small vessels and glands in the lamina propria as well as crypt abscess were more severe in the active group than in the remission group, while mesenchymal change was more significant in the remission group than in the active group. A significant negative correlation was found between the number of EGs and neutrophils in remitted patients (r = 0.568, P = 0.001). In the active group, EG infiltration was positively correlated with lymphadenosis and formation of folliculi lymphaticus (r = 0.755 and 0.524, respectively; both P < 0.01), and negatively with focal hemorrhage (r = -0.385, P = 0.010). In the remission group, EG infiltration was positively correlated with goblet cell disappearance (r = 0.349, P = 0.046).

CONCLUSION: EG infiltration is a potential parameter for evaluating UC activity.

Defining eosinophilic colitis in children: insights from a retrospective case series

OBJECTIVES

Although it is a well-described syndrome in infants, eosinophilic colitis is a loosely defined and poorly understood diagnosis in older children. The aims of this case series were to characterise colonic eosinophilia in children and to determine whether it represents a distinct clinicopathological condition.

METHODS

We retrospectively reviewed symptomatic children older than 12 months with the principal diagnosis of colonic eosinophilia who presented between January 2000 and February 2007 (n = 38) and a further 10 children whose colonic biopsies were reported as histologically normal. The eosinophil density in all available gastrointestinal biopsies (n = 620) of these children was determined using a validated quantitative morphometric method. Patients were subdivided according to mean colonic eosinophil levels into 3 groups (marked, moderate, or minimal colonic eosinophilia). The following patient information was obtained and compared among patient groups: symptoms prompting endoscopy, atopic history, outcome, serum C-reactive protein and total immunoglobulin E (IgE) levels, erythrocyte sedimentation rate, blood eosinophil count, and endoscopic findings.

RESULTS

In all 3 patient groups, there was a colonic gradient of decreasing eosinophil density from caecum to rectum. Upper gastrointestinal tract biopsies did not exhibit eosinophilia. Although a significant association (P = 0.03) between abnormal total IgE levels and moderate or severe colonic eosinophilia was found, there was no significant difference (P > 0.05) in other patient characteristics. Furthermore, follow-up data did not show a consistent relation between eosinophil density and progression of symptoms.

CONCLUSIONS

We find no association between "eosinophilic colitis," defined as a histologically demonstrated marked colonic eosinophilia, and symptoms, history of atopy, inflammatory markers, or clinical outcome.

Functional gastrointestinal disorders and the potential role of eosinophils

The eosinophil-mast cell-neural pathway may be important in the pathophysiology of functional gastrointestinal disorders characterized by unexplained abdominal pain, disordered defecation, or meal-related discomfort. There is evidence that duodenal eosinophils are increased in functional dyspepsia, whereas mast cells are increased in the lower gut in irritable bowel syndrome, directly supporting a role for a hypersensitivity-type reaction in these disorders. The trigger may be a pathogen, food, or other allergen in the gut mucosa. This trigger may evoke eosinophils, mast cells, and other components to cascade to up-regulate serotonin release, with modulation of the enteric and central nervous systems, creating a vicious cycle. If correct, this theory suggests treatment should specifically target the eosinophil-mast cell pathway.

Evaluation of site-specific and seasonal variation in colonic mucosal eosinophils

Several systemic disorders and gastrointestinal diseases may be associated with increased colonic mucosal eosinophils, which may vary in number throughout the normal colon. Some investigators have proposed that colonic eosinophilia reflects allergen exposure, although this hypothesis has never been validated, and values quantifying the number of mucosal eosinophils that can be regarded as a normal finding are lacking. The aims of this study were to determine the number of intramucosal eosinophils normally present throughout the colon and evaluate the relationship between colonic eosinophilia and seasonal allergen exposure. Eosinophils in the crypt epithelium and lamina propria were evaluated in 198 mucosal biopsy specimens obtained from the ascending (n = 98) and descending (n = 100) colon of patients with normal colonoscopic examinations. The cases were stratified into 12 groups, reflecting the months during which the samples were obtained, and the mean number of mucosal eosinophils was determined for each group. Daily air pollen counts were recorded, and the mean determined for each month. Fifty-five percent of mucosal biopsy specimens from the ascending colon contained eosinophils in the crypt epithelium, compared with only 5% of biopsy specimens from the descending colon (P < .001). Lamina propria eosinophils were, on average, 3 times more numerous in the ascending compared with the descending colon (P < .001). Mucosal eosinophils were slightly more numerous in samples obtained in April and May, corresponding to periods of highest pollen counts, but this relationship was not significant (P > .05). We conclude that intramucosal eosinophils are commonly present in the proximal colon but show only mild fluctuations with ambient allergen exposure.

Educational clinical case series in pediatric allergy and immunology

Eosinophilic inflammation may occur in any part of the intestinal tract from the esophagus to the rectum. Despite 70 yr having passed since the first reference to a case of eosinophilic gastroenteritis, the epidemiology and natural history of eosinophilic gastrointestinal disorders are still poorly known. Insights into their etiology and pathogenesis have revealed an important role for allergens; interleukins 4, 5, and 13; the eotaxin family of chemokines; and eosinophil-derived proteins. Diagnosis is confirmed by typical histologic features in a patient with a suggestive clinical phenotype. Treatment involves eliminating triggering allergens, making dietary restrictions the first choice of therapy in a compliant patient; corticosteroids [topical in eosinophilic esophagitis (EE)], despite the potential for serious side effects, are used with success in refractory and non-compliant patients. In this study we discuss EE and gastroduodenitis against the backdrop of clinical case presentations.

Eosinophilia is induced in the colon of Th2-sensitized mice upon exposure to locally expressed antigen

Eosinophilic inflammation is a feature of a variety of gastrointestinal (GI) disorders including eosinophil-associated GI disorder, allergy, inflammatory bowel disease, and parasite infection. Elucidating the mechanisms of eosinophil infiltration into the GI tract is important to the understanding of multiple disease processes. We hypothesize that eosinophilia in the large intestine (colon) can be induced by an antigen in a host that is associated with Th2-skewed antigen-specific immune responses. To investigate the importance of antigenic triggering, we established polarized antigen-specific Th2 type responses in BALB/c mice, using ovalbumin in conjunction with aluminum hydroxide. Upon challenge at the colonic mucosa through transient (3-4 days) expression of the antigen gene encoded in an adenovirus vector, sensitized animals developed significant subepithelial colonic inflammation, characterized by marked eosinophilic infiltration, and the presence of enlarged and increased numbers of lymphoid follicles. The alterations peaked around day 5 and resolved over the next 5-10 days, and no epithelial cell damage was detected through the entire course. Administration of a control (empty) adenovirus vector did not lead to any pathological changes. These data suggest that colonic eosinophilia can be induced by exposure to an antigen associated with preexisting Th2-skewed responses. Thus the model established here may provide a useful tool to study GI and, in particular, colonic inflammation with respect to underlying mechanisms involved in the recruitment and the immediate function of eosinophils.

Emerging questions regarding eosinophil's role in the esophago-gastrointestinal tract

PURPOSE OF REVIEW

Eosinophilic inflammation of the gastrointestinal tract is either increasing in frequency or being better recognized. Whichever is the case, clinical needs to meet this new challenge include establishing diagnostic criteria, identifying the natural history and determining effective, tolerable treatments.

RECENT FINDINGS

During the last 5 years, the emergence of eosinophilic esophagitis stimulated many case series; the new frontiers relate to understanding disease pathogenesis and maintenance treatments. Eosinophilic gastrointestinal diseases involving the rest of the gastrointestinal tract pose new challenges in understanding the role of eosinophils in intestinal dysmotility and protein loss.

SUMMARY

This review will focus on new clinical developments in the field of eosinophilic gastrointestinal diseases and the contribution of basic studies in understanding eosinophils impact on gastrointestinal inflammation.

Quantity and distribution of eosinophils in the gastrointestinal tract of children

There are a lack of data on the quantity and location of eosinophils in the gastrointestinal tract of healthy individuals. Accordingly, we examined gastrointestinal biopsies obtained during endoscopic evaluation of pediatric patients. Biopsies were previously interpreted as having no diagnostic abnormality. The presence of extracellular eosinophil constituents and the quantity of eosinophils in atopic versus nonatopic individuals was determined. In the esophagus, eosinophils were present in only 2.7% of high-power fields (hpf), with a mean value of 0.03+/-0.10 eosinophils/hpf (mean+/-standard deviation) and a maximum of 1 eosinophil/hpf. Examination of the antrum and fundus revealed similar numbers of eosinophils in the lamina propria (1.9+/-1.3 and 2.1+/-2.4 eosinophils/hpf, respectively), with no eosinophils observed in the surface epithelium. In the small intestine, there were 9.6+/-5.3 (maximum, 26 eosinophils/hpf) and 12.4+/-5.4 eosinophils/hpf (maximum, 28 eosinophils/hpf) in the intercryptal lamina propria of the duodenum and ileum, respectively. The number of eosinophils in the surface epithelium and crypt epithelium was minimal. In the large intestine, the highest concentration of eosinophils was observed in the cecum (20.3+/-8.2 eosinophils/hpf; maximum, 50 eosinophils/hpf), and there were lower concentrations in the transverse and sigmoid colon (16.3+/-5.6 and 8.3+/-5.9 eosinophils/hpf, respectively). The percentage of fields demonstrating extracellular eosinophil granules in all gastrointestinal segments was 70% to 93%, and extracellular granules were most numerous at the edge of the biopsy (P<0.05). Atopic and nonatopic patients had comparable numbers of eosinophils. These data establish baseline gastrointestinal eosinophil values in pediatric patients without apparent pathological disease.