Do We Know What Causes Eosinophilic Esophagitis? A Mechanistic Update

Eosinophil Depletion as a Potential Therapeutic Strategy in Acute and Chronic Intestinal Inflammation Based on a Dextran Sulfate Sodium Colitis Model

BACKGROUND

A role for eosinophils in intestinal inflammation and fibrosis in the context of inflammatory bowel disease has been suggested, yet the precise nature, whether causal or secondary remains debated. Hence, it remains unclear whether targeting eosinophils should be further explored as a treatment option in inflammatory bowel disease.

METHODS

Acute and chronic dextran sulfate sodium colitis was induced in wild-type C57BL/6 mice. Eosinophils were depleted by anti-CCR3 injections before colitis induction in a chronic model and after colitis onset in an acute model in order to investigate the impact of eosinophil depletion on pre-existing colitis. Inflammation was assessed using the disease activity index, macroscopic damage, and histological disease activity score. In the chronic model, fibrosis was assessed by examining colon weight/length ratio, collagen deposition through Martius Scarlet Blue staining, hydroxyproline assay, and COL1A1 expression. Protein and gene expression were assessed using the Meso Scale Discovery platform and real-time quantitative polymerase chain reaction.

RESULTS

In the acute and chronic colitis model, eosinophil depletion resulted in reduced disease activity and faster recovery, as observed via the total area under the curve of the disease activity index (P = .004 and P = .02, respectively), macroscopic damage score (P = .009 and P = .08, respectively), and histological disease activity score (P = .09 and P = .002, respectively). In the acute model, the accelerated recovery was accompanied by an increase in interleukin (IL)-10 (P = .03) and a decrease in IL-4 (P = .03) and IL-6 (P = .009). Colon weight/length ratio and collagen deposition were not affected by eosinophil depletion.

CONCLUSIONS

Eosinophil depletion prevents and decreases intestinal inflammation in a preclinical dextran sulfate sodium model without affecting fibrosis. These results pave the way for exploring eosinophil depletion as a novel treatment modality in addressing intestinal inflammation.

Role of Eosinophils in Intestinal Inflammation and Fibrosis in Inflammatory Bowel Disease: An Overlooked Villain?

Eosinophils are leukocytes which reside in the gastrointestinal tract under homeostatic conditions, except for the esophagus which is normally devoid of eosinophils. Research on eosinophils has primarily focused on anti-helminth responses and type 2 immune disorders. In contrast, the search for a role of eosinophils in chronic intestinal inflammation and fibrosis has been limited. With a shift in research focus from adaptive to innate immunity and the fact that the eosinophilic granules are filled with inflammatory mediators, eosinophils are becoming a point of interest in inflammatory bowel diseases. In the current review we summarize eosinophil characteristics and recruitment as well as the current knowledge on presence, inflammatory and pro-fibrotic functions of eosinophils in inflammatory bowel disease and other chronic inflammatory conditions, and we identify research gaps which should be covered in the future.

Biologics in eosinophilic esophagitis

PURPOSE OF REVIEW

Eosinophilic esophagitis (EoE) is a chronic inflammatory disease of the oesophagus whose incidence is on the rise. Despite maximal use of guideline-based therapies including food elimination diets and steroids, many patients remain symptomatic. This review serves to summarize safety and efficacy of monoclonal antibodies in treatment of EoE.

RECENT FINDINGS

There has been an increasing number of biologics under consideration for EoE and several that have undergone clinical trials. mAbs that target specific effectors involved in the disease may offer additional clinical and histologic benefit. In addition, they offer a more benign adverse effect profile than traditional therapies.

SUMMARY

Biologics for treatment of EoE may result in symptom and histologic improvement and has the potential to treat disease with minimal side effects.

Food Allergy and Intolerance: A Narrative Review on Nutritional Concerns

Adverse food reactions include immune-mediated food allergies and non-immune-mediated intolerances. However, this distinction and the involvement of different pathogenetic mechanisms are often confused. Furthermore, there is a discrepancy between the perceived vs. actual prevalence of immune-mediated food allergies and non-immune reactions to food that are extremely common. The risk of an inappropriate approach to their correct identification can lead to inappropriate diets with severe nutritional deficiencies. This narrative review provides an outline of the pathophysiologic and clinical features of immune and non-immune adverse reactions to food-along with general diagnostic and therapeutic strategies. Special emphasis is placed on specific nutritional concerns for each of these conditions from the combined point of view of gastroenterology and immunology, in an attempt to offer a useful tool to practicing physicians in discriminating these diverging disease entities and planning their correct management. We conclude that a correct diagnostic approach and dietary control of both immune- and non-immune-mediated food-induced diseases might minimize the nutritional gaps in these patients, thus helping to improve their quality of life and reduce the economic costs of their management.

Eosinophilic Esophagitis: Update on Diagnosis and Treatment in Pediatric Patients

Eosinophilic esophagitis (EoE) is a chronic immune-mediated inflammatory disorder characterized by symptomatic esophageal dysfunction and an eosinophil-predominant inflammation of the esophagus. EoE arises from interaction between genetic and environmental factors. In pediatric patients, clinical manifestations vary depending on age, from a gastroesophageal reflux disease (GERD)-like condition to severe dysphagic symptoms. Upper endoscopy is considered the gold standard for diagnosis and monitoring of EoE; however, significant efforts are underway to identify noninvasive diagnostic tools and biomarkers to avoid repetitive invasive procedures. Therapeutic first-line options currently available for EoE are elimination diets, proton pump inhibitors (PPIs), and steroids. The aim of treatment is to improve clinical symptoms while obtaining mucosal healing and avoiding long-term complications. Dietary treatment options comprise different empiric diets or an exclusively amino acid formula. Despite the efficacy of diets, compliance is often challenging. PPIs and topical steroids represent the main pharmacological options for EoE, and both can induce and maintain remission. Topical steroids have been reported as more effective, but data on long-term safety remain insufficient for both these and PPIs. Endoscopic dilations are currently reserved for severe untreated fibrostenotic disease unresponsive to medical therapies. Several biologic agents are available but not yet approved for EoE.

Eosinophilic esophagitis: imaging features with endoscopic and pathologic correlation

OBJECTIVE

We aim to review the imaging features of eosinophilic esophagitis on fluoroscopy and present how they can correlate with endoscopic and pathologic findings.

RESULTS

Eosinophilic esophagitis is a chronic immune-mediated disease that results in esophageal dysfunction. Upper esophagogastroduodenoscopy is high yield and required for biopsies to demonstrate the hallmark histologic findings of eosinophil-predominant inflammation. While esophagogastroduodenoscopy is currently mandatory for diagnosis, imaging findings can provide valuable information regarding the structural and functional properties of the esophagus. In addition, fluoroscopic studies may be very helpful in the setting of subtle findings and to evaluate fibrotic remodeling changes.

CONCLUSION

Radiologic examinations are a valuable tool in the assessment of eosinophilic esophagitis and can highlight changes of fibrostenotic disease, as overall narrowing can be more conspicuous fluoroscopically than endoscopically. As the disease increases in prevalence, it is critical that physicians recognize this condition and facilitate diagnosis and treatment.

Eosinophilic esophagitis in children: doubts and future perspectives

Background

Eosinophilic esophagitis (EoE) is a chronic immune-mediated inflammatory disorder and represents the leading cause of food impaction. The pathogenesis of EoE is the result of an interplay between genetic, environmental and host immune system factors. New therapeutic approaches for EoE have been proposed. In this manuscript we review the current evidence regarding EoE management in pediatric age, with a particular focus on new findings related to the efficacy and safety of monoclonal antibodies.

Main body

Conventional therapies have failed in treating some patients with EoE, which then requires aggressive procedures such as esophageal dilatation. The most effective available medical therapy for EoE is swallowed topic corticosteroids (fluticasone propionate and budesonide), which have two main drawbacks: they are related to well-known adverse effects (especially in the paediatric population), and there are not enough long-term data to confirm that they are able to reverse the remodelling process of the esophageal mucosa, which is the major cause of EoE symptoms (including dysphagia, abdominal pain, nausea, obstruction, perforation and vomiting). The monoclonal antibodies appear to be an interesting therapeutic approach. However, the studies conducted until now have shown substantial histological improvement not coupled with significant clinical improvements and no significant relationship between a decreasing number of eosinophils and clinical symptoms, highlighting the importance in the pathogenesis of EoE of cells such as T-helper cells, mast cells, B cells, epithelial cells and natural killer cells.

Conclusions

Monoclonal antibodies targeting a signal involved in the pathogenesis of EoE may not break the complex self-propagating inflammatory activation responsible for perpetuation of the inflammatory response and the development of symptoms and complications. We speculate that combined biological therapies targeting more than one molecule or cell may provide better results, with conventional therapies potentially enhancing the effects of antibodies. However, further studies should aim to find the best therapeutic approach to target the cells involved in the remodelling process and to reverse the histological changes in this complex clinical condition.

Inter-institutional variations regarding Barrett's esophagus diagnosis

BACKGROUND

Barrett's esophagus (BE) is a known precursor for development of esophageal adenocarcinoma and surveillance of affected patients is necessary when cancer progression risk is considered to be high. However, the accuracy of BE diagnosis may not be homogenous among institutions with endoscopy units. We investigated inter-institutional variability by examining the accuracy of endoscopic diagnosis of BE at 4 different hospitals.

METHODS

The accuracy of BE diagnosis at the 4 hospitals was retrospectively reviewed by 6 expert endoscopists, who independently reviewed endoscopic images of approximately 500 consecutive patients examined at each hospital without information regarding the diagnosis by the on-site endoscopists. When the expert reviewers made different diagnosis, a final diagnosis was made by consensus. That was then compared with the diagnosis of the attending endoscopists at each hospital and their concordance was calculated separately for each endoscopy unit. In addition, the relationship between diagnostic accuracy and endoscopic experience was assessed.

RESULTS

The prevalence of BE diagnosis by the on-site endoscopists was not homogenous and varied widely (17.2-96.8%). In 1 hospital, over-diagnosis was the cause of dissimilarity, while under-diagnosis was the cause in two hospitals. Diagnostic accuracy by the attending endoscopists in all 4 hospitals ranged from 44.6 to 83.1% (P < 0.05). There was no significant association between diagnostic accuracy and endoscopic experience or board licensing status of the on-site endoscopists.

CONCLUSION

Diagnostic accuracy for BE was not homogenous among 4 hospitals, and problems related to over- and under-diagnosis should be considered.

Monoclonal Antibodies for Treatment of Eosinophilic Esophagitis

Eosinophilic esophagitis (EoE) is a chronic inflammatory disease of the esophagus affecting both children and adults, with debilitating and progressive symptoms. EoE has shown an explosive epidemiological rise in the past few decades. Many patients experience a poor level of disease control despite maximal use of available guideline-based therapies, which seriously hampers their quality of life. Diet restrictions and systemic and topical corticosteroids are the current mainstays of EoE therapy, but are associated with significant efficacy, treatment compliance, and safety issues such as oral or esophageal candidiasis, growth retardation, osteopenia, osteoporosis, glucose intolerance, and cataract formation. As EoE is a chronic inflammatory disease, immune cells and cytokines are responsible for the inflammatory response and symptoms. Monoclonal antibodies specifically targeting these pathophysiologic effectors offer more potent relief of histologic and clinical disease features while keeping off-target adverse effects to a minimum. Herein, we have reviewed the current evidence regarding efficacy and safety of monoclonal antibodies including mepolizumab (anti-IL-5), reslizumab (anti-IL-5), QAX576 (anti-IL-13), omalizumab (anti-immunoglobulin-E), and infliximab (anti-TNF-α) in treatment of EoE. Our review indicates that although the use of monoclonal antibodies for EoE treatment is safe with limited and reversible adverse events, however, it is not yet possible to reach a final verdict on the efficacy of mAbs in EoE. Future well-designed studies are needed to clarify the exact role of mAbs in EoE.

Impact of smoking, alcohol consumption, and NSAID use on risk for and phenotypes of eosinophilic esophagitis

There are few data exploring modifiable risk factors for eosinophilic esophagitis (EoE). We aimed to determine if smoking, alcohol consumption, and nonsteroidal anti-inflammatory drug (NSAID) use were risk factors for EoE, and to assess their impact on EoE phenotypes and treatment outcomes. We performed a case-control study analyzing data collected from a prospective cohort of adults undergoing upper endoscopy for symptoms of esophageal dysfunction. Incident EoE cases were diagnosed via consensus guidelines. Exposure data were collected via standardized patient questionnaire. Follow-up assessments for cases were made after treatment, with histologic response defined as <15 eosinophils per high-power field (eos/hpf). Exposures were compared between EoE cases and controls, among EoE cases with and without fibrostenosis, and among EoE responders and nonresponders. A total of 115 cases and 225 controls were analyzed. Cases were less likely to have ever smoked cigarettes (23% vs. 47%, P < 0.001) or currently use NSAIDs (17% vs. 40%, P < 0.001) compared to controls. These relations persisted after multivariate analysis. Although alcohol use was more common among cases (75% vs. 51%, P < 0.001), the effect was abrogated after multivariate analysis. Smoking, alcohol, and NSAID use were not associated with the fibrostenotic phenotype. There was a trend toward improved histologic response among EoE patients concomitantly using NSAIDs (87% vs. 63%, P = 0.08; aOR 6.97 (95% CI: 0.81-60.3). In conclusion, NSAID and smoking were inversely associated with EoE compared to endoscopy-based controls. Alcohol use was more prevalent in the EoE cases, although not an independent risk factor. Concomitant NSAID use may improve treatment response and is worthy of future study.