STAT6 gain-of-function variant exacerbates multiple allergic symptoms.

BACKGROUND: Allergic diseases were long considered to be complex multifactorial disorders. However, recent findings indicate that severe allergic inflammation can be caused by monogenic immune defects. OBJECTIVES: We sought to clarify the molecular pathogenesis of a patient with early-onset multiple allergic diseases, a high serum IgE level, hypereosinophilia, treatment-resistant severe atopic dermatitis with increased dermal collagen fiber deposition, and eosinophilic gastrointestinal disorder with numerous polypoid nodules. METHODS: A missense variant in STAT6 was identified, and its function was examined using peripheral blood, transfected HEK293 cells, lymphoblastoid cell lines, and knock-in mice with the corresponding mutation. RESULTS: Whole-exome sequencing identified a de novo heterozygous missense variant in signal transducer and activator of transcription 6 (STAT6) (p.Asp419Asn). Luciferase reporter assay revealed that the transcriptional activity of this STAT6 mutant was upregulated even without IL-4 stimulation. Phosphorylation of STAT6 was not observed in either the patient's TH2 cells or lymphoblastoid cell lines without stimulation, whereas it was induced more strongly in both by IL-4 stimulation compared with healthy controls. STAT6 protein was present in the nuclear fraction of the lymphoblastoid cell lines of the patient even in the absence of IL-4 stimulation. The patient's gastric mucosa showed upregulation of STAT6-, fibrosis-, and germinal center formation-related molecules. Some of the knock-in mice with the corresponding mutation spontaneously developed dermatitis with skin thickening and eosinophil infiltration. Moreover, serum IgE levels and mRNA expression of type 2 cytokines were increased in the knock-in mice-with or without development of spontaneous dermatitis-compared with the wild-type mice. CONCLUSIONS: A novel STAT6 gain-of-function variant is a potential cause of primary atopic disorders.

A nationwide survey of non-IgE-mediated gastrointestinal food allergies in neonates and infants.

BACKGROUND: Non-IgE-mediated gastrointestinal food allergies (non-IgE-GIFAs) seem to be increasing rapidly worldwide. However, nationwide studies have been limited to food-protein-induced enterocolitis (FPIES) and food-protein-induced allergic proctocolitis (FPIAP), with little attention to other non-IgE-GIFA subgroups. The aim of this study was to elucidate the clinical features of all patients with non-IgE-GIFAs, not just certain subgroups. METHODS: We conducted a nationwide cross-sectional survey of non-IgE-GIFAs in Japan from April 2015 through March 2016. A questionnaire was sent to hospitals and clinics throughout Japan. The questionnaire asked about the number of physician-diagnosed non-IgE-GIFA patients, the status of fulfillment of the diagnostic criteria, tentative classification into 4 clusters based on the initial symptoms, the day of onset after birth, complications, and the suspected offending food(s). RESULTS: The response rate to that questionnaire was 67.6% from hospitals and 47.4% from clinics. Analyses were conducted about "diagnosis-probable" patient cohort (n = 402) and the "diagnosis-confirmed" patients (n = 80). In half of the reported non-IgE-GIFA patients, onset occurred in the neonatal period. The patients were evenly distributed among 4 non-IgE-GIFA clusters. In Cluster 1, with symptoms of vomiting and bloody stool, the onset showed a median of 7 days after birth, which was the earliest among the clusters. Cow's milk was the most common causative food. CONCLUSIONS: In half of the patients, the onset of non-IgE-GIFAs was in the neonatal period. This highlights the importance of studying the pathogenesis in the fetal and neonatal periods.

Impressions and aspirations from the FDA GREAT VI Workshop on Eosinophilic Gastrointestinal Disorders Beyond Eosinophilic Esophagitis and Perspectives for Progress in the Field.

The US Food and Drug Administration hosted a workshop on July 21, 2021, to discuss the disease characteristics, natural history, and end points to assess treatment benefit in patients with eosinophilic gastrointestinal disorders (EGIDs) beyond eosinophilic esophagitis (EoE). Notably, EGIDs beyond EoE, such as eosinophilic gastritis, eosinophilic enteritis, and eosinophilic colitis, herein referred to as non-EoE EGIDs, are understudied relative to EoE. This workshop provided a forum for open discussion among stakeholders-medical professionals (including their societies and research groups), Food and Drug Administration representatives, an industry representative, and a patient representative-to facilitate drug development. Experts in many disciplines related to EGIDs, including allergy, immunology, epidemiology, gastroenterology, and pathology, and both adult and pediatric clinicians contributed. Herein, we discuss some of the insights of the material presented at the meeting and present perspectives on moving the field forward toward drug approval.

Clinical, histopathological features and efficacy of elimination diet and proton-pump inhibitor therapy in achieving histological remission in Asian children with eosinophilic gastritis.

AIM: Paediatric eosinophilic gastritis (EG) is a rare disorder and existing literature on diagnostic criteria and management remains lacking. We aim to describe the clinical spectrum and assess the efficacy of dietary elimination and proton-pump inhibitor (PPI) therapy, with particular emphasis on histologic remission in children with primary EG. METHODS: We performed a retrospective study of patients aged 0-18 years diagnosed with EG at a single centre in Singapore from 2013 to 2021. EG was diagnosed based on histological criteria of infiltration of >30 eosinophils per high-power film (HPF) in >5 separate HPFs from gastric biopsies, in the absence of other causes. First-line treatment consisted of PPI therapy and empiric 1-6 food elimination diet (FED). Outcomes measured were clinical, endoscopic and histological remission (defined as eosinophil count <20/HPF in gastric biopsies). RESULTS: Twenty-one (66.7% females) patients were included with median age at diagnosis of 15 months (range:3-192). Majority presented with vomiting (76.2%) and gastrointestinal bleeding (71.4%). Twenty patients were initiated on FED+PPI and 16 had post-treatment biopsies. Clinical, endoscopic and histologic remissions were achieved in 94.7%, 81.3% and 68.8% respectively following FED+PPI. Histologic remission was significantly associated with younger age (9 vs. 132 months; P = 0.026). Four patients who did not respond to FED+PPI were started on oral viscous budesonide, of whom one achieved histological remission and two had clinical improvement. CONCLUSIONS: FED+PPI is effective as first-line treatment in achieving histological remission in paediatric EG particularly in younger patients. Topical corticosteroids can be considered for those who have failed FED+PPI therapy.

Evaluation of long-term course in children with eosinophilic esophagitis reveals distinct histologic patterns and clinical characteristics.

BACKGROUND: Eosinophilic esophagitis (EoE) is a chronic and increasingly prevalent antigen-driven disease. There is a paucity of information on long-term course in children. OBJECTIVE: We sought to understand the longitudinal trajectory of pediatric EoE during routine clinical care. METHODS: We prospectively enrolled children into an EoE database and reviewed their medical and pathologic records over 13 years. RESULTS: From 2011 to 2015, 146 children with EoE seen for their first visit at our center had 2 or more years of follow-up and 3 or more endoscopies over an average follow-up period of 5.13 years (range, 2-13 years). Longitudinal eosinophilic inflammation during treatment demonstrated 3 patterns over time. Children with less than 15 eosinophils/high-power field (hpf) for greater than 75% of their follow-up period were termed continuous responders (CRs). Children with waxing and waning inflammation of less than 15 eosinophils/hpf for less than 75% but 25% or more of the follow-up period were termed intermittent responders (IRs). Nonresponders (NRs) were defined as having less than 15 eosinophils/hpf for less than 25% of their follow-up. Fifty-nine (40%) of 146 patients were CRs, 65 (45%) of 146 were IRs, and 22 (15%) of 146 were NRs. CRs differed from IRs and NRs on the parameter of male/female ratio (1:1 in CRs, 4:1 in IRs, and 6:1 in NRs; P < .001) and in their initial response to any therapy, including proton pump inhibitors (P < .001). Endoscopic severity correlated with esophageal eosinophilia (r = 0.73, P < .001). On multivariate analysis, female sex and initial therapeutic response to medications or elimination diet were associated with long-term control of esophageal eosinophilia. CONCLUSIONS: Long-term pediatric EoE followed 3 different longitudinal trajectories of inflammation. The long-term histologic groups differed significantly in biological sex and initial therapeutic response.

Eosinophils and eosinophil-associated diseases: An update.

The goal of this series is to offer a survey of the latest literature for clinicians and scientists alike, providing a list of important recent advances relevant to the broad field of allergy and immunology. This particular assignment was to cover the topic of eosinophils. In an attempt to highlight major ideas, themes, trends, and advances relevant to basic and clinical aspects of eosinophil biology, a search of articles published since 2015 in the Journal of Allergy and Clinical Immunology and other high-impact journals was performed. Articles were then reviewed and organized, and then key findings were summarized. Given space limitations, many outstanding articles could not be included, but the hope is that what follows provides a succinct overview of recently published work that has significantly added to our knowledge of eosinophils and eosinophil-associated diseases.

The pathology and causes of tissue eosinophilia in the gastrointestinal tract.

Eosinophilic inflammation in the gastrointestinal tract may occur as a primary eosinophilic disorder or as a secondary response with other causes. Primary eosinophilic gastrointestinal disorders (EGIDs) are Th2-mediated allergic diseases that overlap pathogenetically with atopic conditions involving other organs. The pathological diagnosis of primary EGIDs can be challenging, as the quantity of eosinophils considered to be 'abnormal' is difficult to define, and the diagnosis, by definition, requires exclusion of the far more common secondary causes. Our understanding of the basic biology and natural history of eosinophilic oesophagitis has advanced considerably over the last decade, whereas other EGIDs have proven more difficult to characterize; nonetheless, some recent advances have been made. This review summarizes current knowledge regarding the clinical presentation, diagnosis, natural history and treatment of EGIDs, including eosinophilic oesophagitis. We also draw attention to the numerous secondary causes of tissue eosinophilia in the gastrointestinal tract, and suggest a practical approach to the histological assessment, diagnosis and reporting of EGIDs.

Innate lymphoid cells in allergic and nonallergic inflammation.

In the last decade, the full picture of the role of innate lymphoid cells (ILCs) has been gradually revealed. ILCs are classified into 3 groups based on their transcription factors and cytokine production patterns, which mirror helper T-cell subsets. Unlike T cells and B cells, ILCs do not have antigen receptors. They promptly respond to multiple tissue-derived factors, such as cytokines and alarmins, and produce multiple proinflammatory and immunoregulatory cytokines. It has been reported that ILC-derived cytokines are important for the induction and regulation of inflammation. Accumulating evidence suggests that ILCs play substantial roles in protection against infection and the pathogenesis of inflammatory diseases, such as allergic diseases and autoimmune diseases. Different ILC subsets localize in distinct tissue/organ niches and receive tissue-derived signals on different types of inflammation, which allows them to acquire diverse phenotypes with specialized effector capacities. In this review we highlight the roles of ILCs in a variety of organs, such as the airway, skin, and gastrointestinal tract, in the context of allergic and nonallergic inflammation.

Molecular diagnosis of eosinophilic esophagitis by gene expression profiling.

BACKGROUND & AIMS: Gene expression profiling provides an opportunity for definitive diagnosis but has not yet been well applied to inflammatory diseases. Here we describe an approach for diagnosis of an emerging form of esophagitis, eosinophilic esophagitis (EoE), which is currently diagnosed by histology and clinical symptoms. METHODS: We developed an EoE diagnostic panel (EDP) comprising a 96-gene quantitative polymerase chain reaction array and an associated dual-algorithm that uses cluster analysis and dimensionality reduction using a cohort of randomly selected esophageal biopsy samples from pediatric patients with EoE (n = 15) or without EoE (non-EoE controls, n = 14) and subsequently vetted the EDP using a separate cohort of 194 pediatric and adult patient samples derived from both fresh or formalin-fixed, paraffin-embedded tissue: active EoE (n = 91), control (non-EoE and EoE remission, n = 57), histologically ambiguous (n = 34), and reflux (n = 12) samples. RESULTS: The EDP identified adult and pediatric patients with EoE with approximately 96% sensitivity and approximately 98% specificity, and distinguished patients with EoE in remission from controls, as well as identified patients exposed to swallowed glucorticoids. The EDP could be used with formalin-fixed, paraffin-embedded tissue RNA and distinguished patients with EoE from those with reflux esophagitis, identified by pH-impedance testing. Preliminary evidence showed that the EDP could identify patients likely to have disease relapse after treatment. CONCLUSIONS: We developed a molecular diagnostic test (referred to as the EDP) that identifies patients with esophagitis in a fast, objective, and mechanistic manner, offering an opportunity to improve diagnosis and treatment, and a platform approach for other inflammatory diseases.

Eosinophilic colitis is a sporadic self-limited disease of middle-aged people: a population-based study.

AIM: Eosinophilic colitis (EC) is a rare manifestation of eosinophilic gastrointestinal disorders. Due to its rarity, little information is available on its natural history. METHOD: From the single population-based pathology database of the Calgary Health Region (comprising a population of 1.28 million in 2008), cases of EC during the period 1996-2008 were identified. Medical records of all adults diagnosed with EC were identified and the pathology reviewed. The patients were then contacted for follow-up using a standardized questionnaire. RESULTS: Seven cases of EC (four in women) were identified, with a median follow-up of 45 (23-79) months. The median age at diagnosis was 42 (22-70) years. Symptoms at diagnosis were abdominal pain (86%), nonbloody diarrhoea (57%), bloody diarrhoea (29%) and significant (>10%) weight loss (29%). Three patients gave a history of allergic reactions to drugs and four reported allergy to cows' milk. Endoscopic findings were nonspecific, ranging from oedema to small aphthous ulceration. An eosinophilic infiltrate was identified in the lamina propria in the initial colonic biopsy in all patients. Over the longer term, three patients experienced spontaneous resolution without treatment. Two continued to have mild diarrhoea and abdominal cramps but did not require medical therapy. Two patients required medical treatment by 5-aminosalicylic acid, with one requiring prednisone and azathioprine maintenance therapy. CONCLUSION: Eosinophilic colitis is a rare mostly self-limiting disease affecting middle-aged adults. It usually has a mild clinical course and drug treatment is not usually necessary. When required, drug treatment follows the standard medication for other inflammatory bowel disease.

High prevalence of eosinophilic esophagitis in patients with inherited connective tissue disorders.

BACKGROUND: Eosinophilic esophagitis (EoE) is an emerging chronic inflammatory disease mediated by immune hypersensitization to multiple foods and strongly associated with atopy and esophageal remodeling. OBJECTIVE: We provide clinical and molecular evidence indicating a high prevalence of EoE in patients with inherited connective tissue disorders (CTDs). METHODS: We examined the rate of EoE among patients with CTDs and subsequently analyzed esophageal mRNA transcript profiles in patients with EoE with or without CTD features. RESULTS: We report a cohort of 42 patients with EoE with a CTD-like syndrome, representing 0.8% of patients with CTDs and 1.3% of patients with EoE within our hospital-wide electronic medical record database and our EoE research registry, respectively. An 8-fold risk of EoE in patients with CTDs (relative risk, 8.1; 95% confidence limit, 5.1-12.9; χ(2)1 = 112.0; P < 10(-3)) was present compared with the general population. Esophageal transcript profiling identified a distinct subset of genes, including COL8A2, in patients with EoE and CTDs. CONCLUSION: There is a remarkable association of EoE with CTDs and evidence for a differential expression of genes involved in connective tissue repair in this cohort. Thus, we propose stratification of patients with EoE and CTDs into a subset referred to as EoE-CTD.

Pathophysiology of Non-Esophageal Eosinophilic Gastrointestinal Disorders.

Eosinophilic gastrointestinal disorder (EGID) is an umbrella term encompassing a group of chronic, immune-mediated disorders characterized by eosinophil-rich inflammation affecting one or more segments of the gastrointestinal tract. A recent consensus in nomenclature and emerging data made possible through multi-center consortia are beginning to unravel the molecular and cellular underpinnings of EGIDs below the esophagus. These emerging findings are revealing both overarching commonalities related to a food allergen-driven, chronic, Th2-mediated immune response as well as location-specific nuances in the pathophysiology of the collective EGIDs. Altogether, these advances offer promise for improved diagnoses and more efficacious interventional strategies.

Dupilumab Leads to Clinical Improvements including the Acquisition of Tolerance to Causative Foods in Non-Eosinophilic Esophagitis Eosinophilic Gastrointestinal Disorders.

A recent report showed that most pediatric cases of non-eosinophilic esophagitis (EoE) eosinophilic gastrointestinal disorders (EGIDs) (non-EoE EGIDs) are persistent and severe compared with those of EoE, thus requiring further effective therapeutic approaches. In this study, we present the first case based on a systematic search of non-EoE EGID for which tolerance to causative foods and histological and symptomatic improvements were achieved following dupilumab administration, after elimination diets and omalizumab and mepolizumab treatments. Driven by this case, we investigated the efficacies of biological treatments in non-EoE EGID cases based on the patient studied herein, and other patients identified in the conducted systematic review. Seven articles, including five different biologics, were reviewed. Both clinical efficacies and impact differences among the targeted molecules are demonstrated in this study. Our findings show that dupilumab may affect mechanisms that can suppress symptoms induced by offending foods that are different from those induced by other biologics as identified in the conducted systematic review. Additional studies are required to address the unmet needs of non-EoE EGID treatments.

Successful use of dupilumab for egg-induced eosinophilic gastroenteritis with duodenal ulcer: a pediatric case report and review of literature.

BACKGROUND: Non-esophageal eosinophilic gastrointestinal disorder (non-EoE-EGID) is a rare disease in which eosinophils infiltrate parts of the gastrointestinal tract other than the esophagus; however, the number of patients with non-EoE-EGID has been increasing in recent years. Owing to its chronic course with repeated relapses, it can lead to developmental delays due to malnutrition, especially in pediatric patients. No established treatment exists for non-EoE-EGID, necessitating long-term systemic corticosteroid administration. Although the efficacy of dupilumab, an anti-IL-4/13 receptor monoclonal antibody, for eosinophilic esophagitis, has been reported, only few reports have demonstrated its efficacy in non-EoE EGIDs. CASE PRESENTATION: A 13-year-old boy developed non-EoE-EGID with duodenal ulcers, with chicken eggs as the trigger. He was successfully treated with an egg-free diet, proton pump inhibitors, and leukotriene receptor antagonists. However, at age 15, he developed worsening upper abdominal pain and difficulty eating. Blood analysis revealed eosinophilia; elevated erythrocyte sedimentation rate; and elevated levels of C-reactive protein, total immunoglobulin E, and thymic and activation-regulated chemokines. Upper gastrointestinal endoscopy revealed a duodenal ulcer with marked mucosal eosinophilic infiltration. Gastrointestinal symptoms persisted even after starting systemic steroids, making it difficult to reduce the steroid dose. Subcutaneous injection of dupilumab was initiated because of comorbid atopic dermatitis exacerbation. After 3 months, the gastrointestinal symptoms disappeared, and after 5 months, the duodenal ulcer disappeared and the eosinophil count decreased in the mucosa. Six months later, systemic steroids were discontinued, and the duodenal ulcer remained recurrence-free. The egg challenge test result was negative; therefore, the egg-free diet was discontinued. Blood eosinophil count and serum IL-5, IL-13, and eotaxin-3 levels decreased after dupilumab treatment. The serum levels of IL-5 and eotaxin-3 remained within normal ranges, although the blood eosinophil counts increased again after discontinuation of oral prednisolone. CONCLUSIONS: Suppression of IL-4R/IL-13R-mediated signaling by dupilumab may improve abdominal symptoms and endoscopic and histologic findings in patients with non-EoE-EGID, leading to the discontinuation of systemic steroid administration and tolerance of causative foods.

Mortality and cancer in eosinophilic gastrointestinal disorders distal to the esophagus: nationwide cohort study 1990-2017.

BACKGROUND: Eosinophilic gastrointestinal disorders (EGIDs) include inflammatory conditions with enteric infiltration of eosinophils and resulting symptoms. This study aims to examine a population-based sample of patients for prevalence, mortality, and cancer risk in EGIDs distal to the esophagus. METHODS: Nationwide, population-based cohort study. EGID was identified through relevant biopsy codes from Sweden's all 28 pathology departments through the ESPRESSO cohort. Individuals with EGID were then matched to general population reference individuals with similar age and sex. Study participants were linked to Swedish healthcare registers. Through Cox regression, we calculated adjusted hazard ratios (aHRs) adjusting for sex, age, county, calendar period, and education. RESULTS: In total, 2429 patients (56% female) were found to have EGID distal to the esophagus, representing a prevalence of about 1/4800 in the Swedish population. Mean age was 44 years with 11% children at the time of diagnosis. Mortality was increased 17% in patients with EGIDs compared to reference individuals (aHR = 1.17; 95%CI = 1.04-1.33). Excess mortality was seen in gastric and small bowel eosinophilic disease, but not colonic disease (aHR = 1.81; 95%CI = 1.32-2.48, aHR = 1.50; 95%CI = 1.18-1.89, and aHR = 0.99; 95%CI = 0.85-1.16, respectively). Cause specific mortality was driven by cancer-related death (aHR = 1.33; 95%CI = 1.05-1.69). However, this study failed to show an increase in incident cancers (aHR = 1.14; 95%CI = 0.96-1.35). Comparison of EGID individuals with their siblings yielded similar aHRs. CONCLUSIONS: This study found an increased risk of death in patients with EGIDs distal to the esophagus, with cancer death driving the increase. Proximal gut disease seems to confer the greatest risk. There was no increase in incident cancers.

Organ-Specific Hypereosinophilic Syndrome Presenting as Eosinophilic Gastroenteritis.

Gastrointestinal (GI) diseases have a substantial impact on the population health and healthcare resources of the United States. They constitute billions of dollars in expenditure and millions of office and hospital visits. With advancing diagnostic and treatment modalities, rare diseases are increasingly recognized and managed. However, after close to 80 years since the first description, eosinophilic GI disorders (EGID) are still uncommon, and only around 300 cases have been reported to date. Hypereosinophilic syndrome (HES) is well studied, but there are still no guidelines to direct management. We report the case of a 56-year-old female who presented with gastroenteritis and a persistent eosinophil count above 7 x 109/L. Imaging was suggestive of bowel wall thickening, and endoscopy revealed normal-appearing mucosa. However, histologic examination revealed eosinophilic infiltration of the GI tract. She was diagnosed with HES and treated with oral prednisone with remarkable improvement of her symptoms.

Two Cases of Eosinophilic Gastroenteritis With Rare Manifestations Revealed in Medical Checkup Findings.

Eosinophilic gastroenteritis (EGE) is characterized by dense infiltration of eosinophils in gastrointestinal tissues, resulting in morphological and functional abnormalities of the gastrointestinal tract. EGE susceptibility is most common among individuals aged 40-50 years old, and hence it is likely that affected patients will be encountered at the time of a medical checkup. In this report, we present two rare cases of EGE that presented interesting manifestations in findings obtained in a fluoroscopic examination performed at an annual medical checkup. Accumulation of case reports is important to provide information to pathologists to enable them to make correct early diagnosis and begin effective treatment at the earliest.

Eosinophilic Disorders of the Gastrointestinal Tract.

Eosinophilic gastrointestinal disorders represent a spectrum of disorders demonstrating gastrointestinal eosinophilia without any known cause for eosinophilia. Pathogenesis is not clearly established, but immune responses to dietary antigens are implicated. These disorders affect children and adults and are seen in association with allergic disorders. Eosinophilic esophagitis is diagnosed in the setting of mucosal eosinophilia on endoscopic biopsy and symptoms of esophageal dysfunction. Eosinophilic gastroenteritis is also diagnosed with endoscopic biopsies. Eosinophilic colitis commonly presents with lower gastrointestinal symptoms and is a diagnosis of exclusion.

Eosinophilic gastrointestinal disorders associated with autoimmune connective tissue disease.

OBJECTIVES: To determine the clinical and pathological characteristics of eosinophilic gastrointestinal disease (EGID) associated with autoimmune connective tissue disease (CTD). METHODS: Systematic literature review. RESULTS: Twenty cases of CTD associated with EGID were identified. Systemic lupus erythematosus was the main EGID-associated CTD (35%), followed by rheumatoid arthritis (20%), systemic sclerosis or inflammatory myopathies (15%, each), and Sjögren's syndrome, scleromyositis or other overlapping connective tissue disease (5%, each). No patient had a history of atopy. In contrast with classical EGID among which eosinophilic esophagitis is the most frequent type, eosinophilic gastritis and/or enteritis represented 95% of cases. Gastrointestinal symptoms were often unspecific. Peripheral eosinophilia was found in 67% of cases. Upper and lower gastrointestinal endoscopy showed abnormal findings in only 40% and 30% of cases, respectively. EGID was confirmed by evidence of digestive eosinophilic infiltration, mainly in mucosal or submucosal layer. In all but one patient, the CTD was diagnosed prior to the occurrence of the EGID. In total, 95% of EGID had a favorable outcome, with corticosteroids being used in almost all cases. CONCLUSION: Clinicians should consider EGID as a possible diagnosis and perform gastrointestinal tract biopsies in patients with CTD presenting with gastrointestinal symptoms and unexplained eosinophilia. Conversely, more rarely extra-digestive features during follow-up in patients with EGID may lead to a diagnosis of an associated CTD. More research is needed to better understand the underlying pathophysiological processes leading to eosinophilic gastrointestinal infiltration in patients with CTD.

Eosinophilic colitis: epidemiology, clinical features, and current management.

Primary eosinophilic gastrointestinal disorders (EGIDs) represent a spectrum of inflammatory gastrointestinal disorders in which eosinophils infiltrate the gut in the absence of known causes for such tissue eosinophilia. EGIDs can be subgrouped as eosinophilic esophagitis (EE), eosinophilic gastroenteritis (EG), and eosinophilic colitis (EC). The least frequent manifestation of EGIDs is EC. EC is a heterogeneous entity with a bimodal age distribution, presenting with either an acute self-limited bloody diarrhea in otherwise healthy infants or as a more chronic relapsing colitis in young adults. The pathophysiology of primary EC appears related to altered hypersensitivity, principally as a food allergy in infants and T lymphocyte-mediated (i.e. non-IgE associated) in young adults. In adults, symptoms include diarrhea, abdominal pain, and weight loss. Endoscopic changes are generally modest, featuring edema and patchy granularity. Although standardized criteria are not yet established, the diagnosis of EC depends on histopathology that identifies an excess of eosinophils. Therapeutic approaches are based on case reports and small case series, as prospective randomized controlled trials are lacking. Eosinophilic colitis in infants is a rather benign, frequently food-related entity and dietary elimination of the aggressor often resolves the disorder within days. Adolescent or older patients require more aggressive medical management including: glucocorticoids, anti-histamines, leukotriene receptors antagonists as well as novel approaches employing biologics that target interleukin-5 (IL-5) and IgE. This review article summarizes the current knowledge of EC, its epidemiology, clinical manifestations, diagnosis, and treatment.