Eosinophilic gastrointestinal disorders associated with autoimmune connective tissue disease

The Dual Lens of Endoscopy and Histology in the Diagnosis and Management of Eosinophilic Gastrointestinal Disorders-A Comprehensive Review

Eosinophilic Gastrointestinal Disorders (EGIDs) are a group of conditions characterized by abnormal eosinophil accumulation in the gastrointestinal tract. Among these EGIDs, Eosinophilic Esophagitis (EoE) is the most well documented, while less is known about Eosinophilic Gastritis (EoG), Eosinophilic Enteritis (EoN), and Eosinophilic Colitis (EoC). The role of endoscopy in EGIDs is pivotal, with applications in diagnosis, disease monitoring, and therapeutic intervention. In EoE, the endoscopic reference score (EREFS) has been shown to be accurate in raising diagnostic suspicion and effective in monitoring therapeutic responses. Additionally, endoscopic dilation is the first-line treatment for esophageal strictures. For EoG and EoN, while the literature is more limited, common endoscopic findings include erythema, nodules, and ulcerations. Histology remains the gold standard for diagnosing EGIDs, as it quantifies eosinophilic infiltration. In recent years, there have been significant advancements in the histological understanding of EoE, leading to the development of diagnostic scores and the identification of specific microscopic features associated with the disease. However, for EoG, EoN, and EoC, precise eosinophil count thresholds for diagnosis have not yet been established. This review aims to elucidate the role of endoscopy and histology in the diagnosis and management of the three main EGIDs and to analyze their strengths and limitations, their interconnection, and future research directions.

Successful Treatment of Eosinophilic Enterocolitis in an Adult Patient With Adalimumab

Eosinophilic gastrointestinal diseases are increasing in prevalence, but understanding of their causes and effective treatments remain elusive, especially in adults. We present a case of eosinophilic gastroenteritis and colitis with extraintestinal manifestations that was successfully treated with a tumor necrosis factor α inhibitor, adalimumab.

Joint ESPGHAN/NASPGHAN Guidelines on Childhood Eosinophilic Gastrointestinal Disorders Beyond Eosinophilic Esophagitis

INTRODUCTION

Eosinophilic gastrointestinal disorders beyond eosinophilic esophagitis (non-EoE EGIDs) are rare chronic inflammatory disorders of the gastrointestinal (GI) tract. Diagnosis is based on clinical symptoms and histologic findings of eosinophilic inflammation after exclusion of a secondary cause or systemic disease. Currently, no guidelines exist for the evaluation of non-EoE EGIDs. Therefore, the European Society for Paediatric Gastroenterology, Hepatology and Nutrition (ESPGHAN) and the North American Society for Pediatric Gastroenterology, Hepatology and Nutrition (NASPGHAN) formed a task force group to provide consensus guidelines for childhood non-EoE EGIDs.

METHODS

The working group was composed of pediatric gastroenterologists, adult gastroenterologists, allergists/immunologists, and pathologists. An extensive electronic literature search of the MEDLINE, EMBASE, and Cochrane databases was conducted up to February 2022. General methodology was used in the formulation of recommendations according to the Appraisal of Guidelines for Research and Evaluation (AGREE) II and the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system to meet current standards of evidence assessment.

RESULTS

The guidelines provide information on the current concept of non-EoE EGIDs, disease pathogenesis, epidemiology, clinical manifestations, diagnostic and disease surveillance procedures, and current treatment options. Thirty-four statements based on available evidence and 41 recommendations based on expert opinion and best clinical practices were developed.

CONCLUSION

Non-EoE EGIDs literature is limited in scope and depth, making clear recommendations difficult. These consensus-based clinical practice guidelines are intended to assist clinicians caring for children affected by non-EoE EGIDs and to facilitate high-quality randomized controlled trials of various treatment modalities using standardized, uniform disease definitions.

Food Allergy Characteristics Associated With Coexisting Eosinophilic Esophagitis in FARE Registry Participants

BACKGROUND

Eosinophilic esophagitis (EoE) can coexist in individuals with food allergy.

OBJECTIVE

To evaluate the characteristics of food-allergic patients with and without coexisting EoE using a large food allergy patient registry.

METHODS

Data were derived from 2 Food Allergy Research & Education, Inc, Patient Registry surveys. A series of multivariable regression models were used to evaluate associations between demographic, comorbidity, and food allergy characteristics and the likelihood of reporting EoE.

RESULTS

Five percent (n = 309) of registry participants (n = 6074; ages <1 year->80 years, mean, 20.20 ± 15.37 years) reported having EoE. The odds of having EoE were significantly greater in male participants (adjusted odds ratio [aOR], 1.3; 95% CI, 1.04-1.72) and those with comorbid asthma (aOR, 2.0; 95% CI, 1.55-2.49), allergic rhinitis (aOR, 1.8; 95% CI, 1.37-2.22), oral allergy syndrome (aOR, 2.8; 95% CI, 2.09-3.70), food protein-induced enterocolitis syndrome (aOR, 2.5; 95% CI, 1.34-4.84), and hyper-IgE syndrome (aOR, 7.6; 95% CI, 2.93-19.92), though not atopic dermatitis (aOR, 1.3; 95% CI, 0.99-1.59), when adjusting for demographics (sex, age, race, ethnicity, and geographic location). Those with a greater number of food allergies (aOR, 1.3; 95% CI, 1.23-1.32), more frequent food-related allergic reactions (aOR, 1.2; 95% CI, 1.11-1.24), previous anaphylaxis (aOR, 1.5; 95% CI, 1.15-1.83), and health care utilization for food-related allergic reactions (aOR, 1.3; 95% CI, 1.01-1.67)-specifically intensive care unit admission (aOR, 1.2; 95% CI, 1.07-1.33)-were more likely to have EoE after controlling for demographics. However, no significant difference in ever using epinephrine for food-related allergic reactions was detected.

CONCLUSIONS

These self-reported data showed that coexisting EoE is associated with an increased number of food allergies, food-related allergic reactions per year, and measures of reaction severity, calling attention to the likely increased health care needs of food-allergic patients with EoE.

Analysis of Peripheral Blood Basophils in Pediatric Systemic Lupus Erythematosus

Basophils are the least abundant circulating leukocytes, and their immunological role has not yet been completely elucidated. There is evidence supporting their immunomodulatory role in several pathological settings; recently, studies in both experimental models and humans suggested that basophil homeostasis may be altered in systemic lupus erythematosus (SLE). Here, we first assessed circulating basophils in children affected with pediatric SLE (pSLE). In this cross-sectional study, circulating basophils were enumerated by fluorescence-based flow cytometry analysis in children affected with pSLE, in addition to children suffering from juvenile idiopathic arthritis (JIA) or non-inflammatory/non-rheumatic conditions. This study included 52 pediatric patients distributed in these three groups. We observed a statistically significant reduction of peripherally circulating basophils in children with pSLE compared to the other two groups of patients. This preliminary study is consistent with the available studies in adult patients with SLE showing a reduced number of circulating basophils. However, further research is needed to draw final conclusions on basophils’ homeostasis in pSLE, in addition to their correlation with the disease activity and concomitant therapies.

Eosinophilic Disorders of the Gastrointestinal Tract and Associated Abdominal Viscera: Imaging Findings and Diagnosis

Eosinophilic gastrointestinal disorders (EGIDs) are inflammatory conditions of the gastrointestinal tract that are characterized by tissue eosinophilia and end-organ dysfunction or damage. Primary EGIDs are associated with atopy and other allergic conditions, whereas secondary EGIDs are associated with underlying systemic diseases or hypereosinophilic syndrome. Within the spectrum of EGIDs, eosinophilic esophagitis is the most prevalent. Eosinophilic gastroenteritis and eosinophilic colitis are relatively uncommon. Eosinophilic infiltration of the liver, biliary tree, and/or pancreas also can occur and mimic other inflammatory and malignant conditions. Although endoscopic evaluation is the method of choice for eosinophilic esophagitis, radiologic evaluation of the esophagus plays an important role in the assessment of disease severity. CT and MR enterography are the modalities of choice for demonstrating specific forms of eosinophilic gastroenteritis. CT and MRI are important in the detection of abdominal visceral involvement in EGIDs. Diagnosis is often challenging and relies on symptoms, imaging findings, histologic confirmation of tissue eosinophilia, and correlation with peripheral eosinophilia. Imaging is crucial for identifying characteristic organ-specific findings, although imaging findings are not specific. When promptly treated, EGIDs usually have a benign clinical course. However, a delayed diagnosis and associated surgical interventions have been associated with morbidity. Therefore, a radiologist's knowledge of the imaging findings of EGIDs in the appropriate clinical settings may aid in early diagnosis and thereby improve patient care. An overview of the clinical features and imaging findings of EGIDs and the eosinophilic disorders of associated abdominal viscera is provided. Online supplemental material is available for this article. ^©RSNA, 2022.

Asymptomatic Eosinophilic Infiltration with Endoscopic and Histological Findings Consistent with Eosinophilic Gastritis

Eosinophilic gastritis often presents with gastrointestinal symptoms in the absence of abnormal endoscopic findings. On the other hand, endoscopic changes due to eosinophilic infiltration in an asymptomatic patient are rare. A 29-year-old woman with a history of asthma on steroid inhalers presented for an annual medical checkup. Esophagogastroduodenoscopy revealed diffuse white granular patches in the body of the stomach, suggestive of eosinophilic gastritis. Histology showed over 100 eosinophils per high-power field, also consistent with eosinophilic gastritis. As the absence of symptoms precluded the diagnosis of eosinophilic gastritis, the patient was diagnosed with asymptomatic eosinophilic infiltration of the stomach.

A case of eosinophilic granulomatosis with polyangiitis after prolonged intervals of an anti-interleukin-6 receptor antibody for rheumatoid arthritis

An 83-year-old woman with a history of asthma complained of left abdominal pain and was admitted to our hospital. She was treated with tocilizumab, an anti-interleukin (IL)-6 receptor antibody, with a prolonged interval for rheumatoid arthritis (RA). Laboratory tests revealed a remarkable increase in eosinophil count and inflammatory markers with negative antineutrophil cytoplasmic antibodies. Echocardiography revealed pericardial fluid retention, and contrast-enhanced computed tomography revealed the thickening of the gastric antrum wall. Upper gastrointestinal endoscopy and biopsy revealed eosinophilic infiltration into the gastric mucosal epithelium. She was diagnosed with eosinophilic granulomatosis with polyangiitis (EGPA) with pericarditis and eosinophilic gastroenteritis. High-dose glucocorticoids with intermittent intravenous cyclophosphamide (IVCY) were initiated, resulting in remission. As IL-6 is involved in the pathogenesis of allergic diseases such as asthma, our case can provide insights into the pathogenic role of IL-6 in EGPA as the development of EGPA in our case may have been triggered by IL-6 signals enhanced with tocilizumab interval prolongation.

Eosinophils, a Jack of All Trades in Immunity: Therapeutic Approaches for Correcting Their Functional Disorders

BACKGROUND AND OBJECTIVE

Eosinophils are primitive myeloid cells derived from bonemarrow precursors and require the intervention of interleukin (IL)-5 for their survival and persistence in blood and tissues. Under steady-state conditions, they contribute to immune regulation and homeostasis. Under pathological circumstances, eosinophils are involved in host protection against parasites and participate in allergy and inflammation.

DISCUSSION

Mostly, in asthma, eosinophils provoke airway damage via the release of granule contents and IL-13 with mucus hypersecretion and differentiation of goblet cells. Then, tissue remodeling follows with the secretion of transforming growth factor-β. Eosinophils are able to kill helminth larvae acting as antigen-presenting cells with the involvement of T helper (h)-2 cells and subsequent antibody response. However, they also exert pro-worm activity with the production of suppressive cytokine (IL- 10 and IL-4) and inhibition of nitric oxide. Eosinophils may play a pathogenic role in the course of chronic and autoimmune disease, e.g., inflammatory bowel disease and eosinophilic gastroenteritis, regulating Th2 responses and promoting a profibrotic effect. In atopic dermatitis, eosinophils are commonly detected and may be associated with disease severity. In cutaneous spontaneous urticaria, eosinophils participate in the formation of wheals, tissue remodeling and modifications of vascular permeability. With regard to tumor growth, it seems that IgE can exert anti-neoplastic surveillance via mast cell and eosinophil-mediated cytotoxicity, the so-called allergo-oncology. From a therapeutic point of view, monoclonal antibodies directed against IL-5 or the IL-5 receptors have been shown to be very effective in patients with severe asthma. Finally, as an alternative treatment, polyphenols for their anti-inflammatory and anti-allergic activities seem to be effective in reducing serum IgE and eosinophil count in bronchoalveolar lavage in murine asthma.

CONCLUSION

Eosinophils are cells endowed with multiple functions and their modulation with monoclonal antibodies and nutraceuticals may be effective in the treatment of chronic disease.

Eosinophilic esophagitis-established facts and new horizons

Despite dramatic advances in our understanding of the pathogenesis and course of disease in the relatively short timeframe since the discovery and first description of eosinophilic esophagitis (EoE) less than three decades ago, many open questions remain to be elucidated. For instance, we will need to better characterize atypical clinical presentations of EoE and other forms of esophageal inflammatory conditions with often similar clinical presentations, nut fulfilling current diagnostic criteria for EoE and to determine their significance and interrelationship with genuine EoE. In addition, the interrelationship of EoE with other immune-mediated diseases remains to be clarified. Hopefully, a closer look at the role of environmental factors and their interaction with genetic susceptibility often in context of atopic predisposition may enable identifying the candidate substances/agents/allergens and potentially earlier (childhood) events to trigger the condition. It appears plausible to assume that in the end—comparable to current concepts in other immune-mediated chronic diseases, such as for instance inflammatory bowel disease or asthma bronchiale—we will not be rewarded with the identification of a “one-and-only” underlying pathogenetic trigger factor, with causal responsibility for the disease in each and every EoE patient. Rather, the relative contribution and importance of intrinsic susceptibility, i.e., patient-driven factors (genetics, aberrant immune response) and external trigger factors, such as food (or aero-) allergens as well as early childhood events (e.g., infection and exposure to antibiotics and other drugs) may substantially differ among given individuals with EoE. Accordingly, selection and treatment duration of medical therapy, success rates and extent of required restriction in dietary treatment, and the need for mechanical treatment to address strictures and stenosis require an individualized approach, tailored to each patient. With the advances of emerging treatment options, the importance of such an individualized and patient-centered assessment will increase even further.

Targeted Therapies for Eosinophilic Gastrointestinal Disorders

The growing recognition of eosinophilic gastrointestinal disorders has revealed the limitations of current treatment (mainly based on dietary modification and corticosteroids), and include refractoriness, high recurrence rates, and the need for long-term therapy. Research efforts, mainly in eosinophilic esophagitis (EoE), have unveiled essential pathophysiological mechanisms leading to these disorders, which bear some similarities to those of atopic manifestations and are shared by eosinophilic gastroenteritis (EGE) and eosinophilic colitis (EC). Novel targeted therapies, some imported from bronchial asthma and atopic dermatitis, are currently being assessed in EoE. The most promising are monoclonal antibodies, including those targeting interleukin (IL)-13 (cendakimab) and IL-4 (dupilumab), with phase 3 trials currently ongoing. The potential of anti-integrin therapy (vedolizumab) and Siglec-8 blockers (antolimab) in EGE are also promising. Non-biological therapies for eosinophilic gut disorders, which include preventing the activation of Janus kinase (JAK)-signal transducer and activator of transcription (STAT) and chemoattractant receptor expressed on T helper 2 cells (CRTH2) signaling pathways, and other potential targets that deserve investigation in eosinophilic gut disorders, are reviewed.

Blood Eosinophil Levels and Prognosis of Hospitalized Patients with Acute Exacerbation of Chronic Obstructive Pulmonary Disease

BACKGROUD

Studies about the clinical significance of high eosinophil levels in chronic obstructive pulmonary disease (COPD) are conflicting, and it has been less studied in hospitalized patients with acute exacerbation of COPD (AECOPD).This study was to examine blood eosinophil levels in relation to the prognosis of hospitalized patients with AECOPD.

METHODS

This was a retrospective cohort study of patients with AECOPD as their primary diagnosis and admitted to Beijing Shijitan Hospital, Capital Medical University, from January 2010 to December 2016. The patients were assigned according to the count of eosinophil in peripheral blood at their first hospitalization. Patients were grouped as ≤100, 100-300, and ≥300 eosinophils/µL of peripheral blood. The use of glucocorticoids, duration of hospitalization, in-hospital mortality, and re-hospitalization were examined.

RESULTS

Compared with the 100-300 eosinophils/µL group, the ≤100 eosinophils/µL group showed higher frequencies of fever, respiratory failure, and the use of systemic glucocorticoids. Eosinophil counts were not associated with in-hospital mortality and duration of hospitalization. The multivariable analysis showed that GOLD3/4 (odds ratio (OR)=2.04, 95%CI: 1.20-3.44, P = 0.008), systemic glucocorticoids (OR=1.84, 95%CI: 1.41-2.98, P = 0.012), mechanical ventilation (OR=2.66, 95%CI: 1.36-5.18, P = 0.004), and acute exacerbation in the past year before hospitalization (OR=2.03, 95%CI: 1.27-3.23, P = 0.003) were independently associated with acute exacerbation within 1 year after discharge. Eosinophil count was not associated with acute exacerbation within 1 year after discharge.

CONCLUSIONS

Peripheral blood eosinophil counts are not associated with the 1-year AECOPD prognosis.

Eosinophilic gastroenteritis in an adolescent male with history of chronic bullous disease

Eosinophilic gastroenteritis is a rare inflammatory disorder of the gastrointestinal tract. Although commonly associated with allergic diseases, it is also rarely associated with autoimmune disorders. This case report describes a 17-year-old Filipino male with eosinophilic gastroenteritis, manifesting as abdominal pain, vomiting and diarrhoea. He had no allergic diseases, but he was previously diagnosed with chronic bullous disease. His symptoms improved with the initiation of corticosteroids. To date, this is the first case report of a patient with eosinophilic gastroenteritis and chronic bullous disease.

Morphological signs of connective tissue dysplasia as predictors of frequent post-exercise musculoskeletal disorders

Background

Connective tissue dysplasia (CTD) is a risk factor for musculoskeletal disorders. Changes caused by disorganization of collagen and elastin fibers lead to the inability of withstanding heavy mechanical stress. In clinical practice, diagnosis of these disorders depends on physical and anthropomorphic evaluation.

Methods

Forty-eight patients with frequent post-exercise musculoskeletal disorders were evaluated for CTD. The control group included 36 healthy participants. Both groups were evaluated via therapeutic examination with assessment of anthropometric indicators and physical-physiological evaluation, surveying and gathering of anamnesis. Based on testing results, study participants were evaluated on CTD presence and risk factors.

Results

All experimental group patients had connective tissue dysplasia of moderate and severe degree, with a total score of 49.44 ± 13.1. Certain morphological characteristics showed prevalence, allowing to determine pathognomonic predictors of high predisposition to frequent post-exercise musculoskeletal disorders. Back pain (100%), asthenic syndrome and kyphotic spinal deformation (75%), high gothic palate, hypermobility of joints and the auricles, excessive elasticity (63%), varicose veins of the lower extremities (56%) and hemorrhoids (56%), changes in the shape of the legs and temporomandibular joint (50%) showed to be significant clinical factors indicating possible connective tissue dysplasia.

Conclusions

The presence of these diagnostically significant morphological signs of CTD in humans is a pathognomonic predictor of a high predisposition to frequent injuries. Their early detection helps promote proper appointment of adequate physical activity regimen and develop treatment for the underlying cause.

High Patient Disease Burden in a Cross-sectional, Multicenter Contact Registry Study of Eosinophilic Gastrointestinal Diseases

OBJECTIVES

Clinical features of eosinophilic esophagitis (EoE) have been well-described in the literature, however, characterization of features experienced by patients with other eosinophilic gastrointestinal diseases (EGIDs) is lacking. Using data collected from a patient contact registry, we sought to characterize and contrast patient-reported gastrointestinal and extragastrointestinal symptoms and comorbidities in non-EoE EGIDs, including eosinophilic gastritis, gastroenteritis and colitis, relative to EoE.

METHODS

We conducted a cross-sectional study of contact registry data collected from 2015 to 2018. Statistical comparisons were made using chi-square (categorical measures) and the Mann-Whitney U test (continuous measures). Multivariable analyses were used to evaluate associations between treatment and feelings of isolation.

RESULTS

Of the 715 reporting an EGID diagnosis (n = 525 EoE; n = 190 non-EoE EGID), a higher proportion of those with a non-EoE EGID reported more frequent specific and nonspecific gastrointestinal symptoms, including nausea, abdominal pain, diarrhea, constipation, and bloating (P < 0.01 for all). Participants with a non-EoE EGID were more likely to report higher frequency of fatigue, isolation, and deep muscle or joint pain (P < 0.01 for all). Specific food elimination and elemental formula treatments were associated with increased odds of more frequent (at least weekly) feelings of isolation for participants with EoE (adjusted odds rtaio [aOR]: 2.4; 95% confidence interval [CI]: 1.5--4.1 for specific food elimination and adjusted OR: 1.9; 95% CI: 1.2--3.3 for elemental formula).

CONCLUSIONS

Significant differences exist in the symptoms and comorbidities experienced between those with EoE versus non-EoE EGIDs. Additional investigation is needed to elucidate the factors that may contribute to the high disease burden of these poorly understood conditions.

Eosinophilic Gastroenteritis with a Relapsing and Remitting Course with Presence of Autoimmune Antibodies

Background

Eosinophilic gastroenteritis (EGE) is an uncommon disease characterized by eosinophilic infiltration of the digestive tract, which occurs due to an uncertain aetiology. Although autoimmune diseases can later present as EGE, it is unusual for EGE to have positive autoimmune antibodies without the presence of an overt autoimmune disease. Case presentation. We report a 38-year-old previously healthy man who presented with abdominal discomfort and loose stools with pleural and peritoneal effusions progressing over several weeks. His investigations revealed severe eosinophilia in peripheral blood and ascitic fluid, and a laparoscopic full-thickness biopsy from the ileum demonstrated infiltration of eosinophils in all three layers of the intestine. There were no clinical features or investigations suggestive of parasitic disease, other diseases associated with eosinophilia, or autoimmune disease. Further investigations showed a highly positive ANA, positive p-ANCA, but did not meet the criteria to diagnose a specific autoimmune disease. The eosinophilia responded to an elimination diet with gradual resolution of eosinophilia and effusions, and once it reappeared after introduction of a normal diet.

Conclusion

EGE presenting as peripheral blood and ascitic fluid eosinophilia with the presence of pleural and/or peritoneal effusions is uncommon. Eosinophilic gastroenteritis can be associated with autoantibody positivity without any evidence of overt autoimmune disease manifestations. Elimination diet can be used as a potential option to prevent recurrences of EGE.

Eosinophilic Gastrointestinal Diseases in Children: A Practical Review

Primary eosinophilic gastrointestinal diseases (EGIDs) represent a heterogeneous group of disorders characterized by eosinophilic inflammation in the absence of known causes for eosinophilia, selectively affecting different segments of the gastrointestinal tract. While pediatric eosinophilic esophagitis (EoE) is a well-defined disease with established guidelines, Eosinophilic Gastritis (EoG), Eosinophilic Gastroenteritis (EoGE) and Eosinophilic Colitis (EoC) remain a clinical enigma with evidence based on limited anecdotal case reports. Large cross-sectional studies in the US defined a prevalence of EoG and EoGE ranging from 1,5 to 6,4/100.000 and from 2,7 to 8,3/100.000 subjects respectively, while the prevalence of EoC ranges from 1,7 to 3,5/100.000 subjects. Regarding the pathogenesis, it is hypothesized that EGIDs result from the interplay between genetic predisposition, intestinal dysbiosis and environmental triggers. Clinically, EGIDs might present with different and nonspecific gastrointestinal symptoms depending on the involved intestinal tract and the extension of eosinophilic inflammatory infiltrate. The diagnosis of EGIDs requires: 1. recurrent gastrointestinal symptoms, 2. increased eosinophils for high power field in biopsy specimens, 3. absence of secondary causes of gastrointestinal eosinophilia. No validated guidelines are available on the clinical management of patients with EGIDs. Evidence from case reports and small uncontrolled case series suggests the use of dietary and corticosteroids as the first-line treatments. Considering the clinical follow-up of EGIDs, three different patterns of disease course are identified: single flare, recurring course-disease and chronic course-disease. This review will focus on pediatric EGIDs distal to esophagus, including Eosinophilic Gastritis (EoG), Eosinophilic Gastroenteritis (EoGE) and Eosinophilic Colitis (EoC).

Eosinophilic colitis and colonic eosinophilia

PURPOSE OF REVIEW

Eosinophilic colitis is a rare condition, with a prevalence rate in the USA of 2-3/100 000 persons (0.003%), but diagnosed in 0.1% of biopsies in those colonoscoped for diarrhoea. Secondary colonic eosinophilia is more common and associated with systemic, colonic and infectious diseases. In this review, the latest advances in diagnosis, treatment and prognosis are summarized and discussed.

RECENT FINDINGS

What constitutes a 'normal' count of eosinophils is poorly documented but there are recent studies that establish normal colonic eosinophil ranges as well as distinguishing histological and clinical findings in primary eosinophilic colitis and secondary colonic eosinophilia in children and adults. Primary eosinophilic colitis is rare, relatively straightforward to diagnose, but may be difficult to treat. Colonic eosinophilia may be overt in parasite infection and connective tissue disease. More subtle, secondary colonic eosinophilia is a useful biomarker for gastrointestinal diseases, such as inflammatory bowel disease, colonic spirochaetosis and collagenous colitis, but the eosinophilia may more often be overlooked. A limited number of drugs are also known to cause left sided colonic eosinophilia such as clopidogrel, ibuprofen and oestroprogestinic agents.

SUMMARY

Advances in our understanding of primary eosinophilic colitis and secondary colonic eosinophilia is progressing and if present, colonic eosinophilia should point the clinician and pathologist to a list of differential diagnoses worth considering to direct optimal management.

Eosinophils in Autoimmune Diseases

Eosinophils are multifunctional granulocytes that contribute to initiation and modulation of inflammation. Their role in asthma and parasitic infections has long been recognized. Growing evidence now reveals a role for eosinophils in autoimmune diseases. In this review, we summarize the function of eosinophils in inflammatory bowel diseases, neuromyelitis optica, bullous pemphigoid, autoimmune myocarditis, primary biliary cirrhosis, eosinophilic granulomatosis with polyangiitis, and other autoimmune diseases. Clinical studies, eosinophil-targeted therapies, and experimental models have contributed to our understanding of the regulation and function of eosinophils in these diseases. By examining the role of eosinophils in autoimmune diseases of different organs, we can identify common pathogenic mechanisms. These include degranulation of cytotoxic granule proteins, induction of antibody-dependent cell-mediated cytotoxicity, release of proteases degrading extracellular matrix, immune modulation through cytokines, antigen presentation, and prothrombotic functions. The association of eosinophilic diseases with autoimmune diseases is also examined, showing a possible increase in autoimmune diseases in patients with eosinophilic esophagitis, hypereosinophilic syndrome, and non-allergic asthma. Finally, we summarize key future research needs.