Translating new developments in eosinophilic esophagitis pathogenesis into clinical practice

Eosinophilic esophagitis, Barrett's esophagus and esophageal neoplasms in the pediatric patient: a narrative review

There are several esophageal disorders that can occur in the pediatric population. Eosinophilic esophagitis (EoE) is an eosinophil predominant inflammatory disease of the esophagus that was first characterized in the early 1900's. EoE is the most common pediatric esophageal inflammatory condition after gastroesophageal reflux disease (GERD). Longstanding GERD is a known risk factor for the development of Barrett's esophagus (BE) in both children and adults. BE is associated with the development of dysplasia and, if left undiagnosed, may progress to the development of esophageal adenocarcinoma (EAC). EAC and esophageal squamous cell carcinoma (ESCC) comprise the majority of childhood esophageal malignant neoplasms. The prevalence of EoE continues to rise within the pediatric population. On the other hand, both BE and esophageal neoplasms remain extremely rare in children. The relationship between a chronic inflammatory condition like EoE to BE and/or esophageal neoplasms remains unclear. The current research of these disease entities is prioritized to further understanding the disease pathogenesis and disease progression, exploring new diagnostic modalities, and developing novel treatments or less invasive therapeutic options. The focus of the following narrative review is to provide a summary of the current clinical practices, future research and their implications on these various esophageal disorders.

Cow's Milk Allergy or Gastroesophageal Reflux Disease-Can We Solve the Dilemma in Infants?

Cow's milk allergy (CMA) and gastro-esophageal reflux disease (GERD) may manifest with similar symptoms in infants making the diagnosis challenging. While immediate reaction to cow's milk protein indicate CMA, regurgitation, vomiting, crying, fussiness, poor appetite, sleep disturbances have been reported in both CMA and GERD and in other conditions such as functional gastrointestinal disorders, eosinophilic esophagitis, anatomic abnormalities, metabolic and neurological diseases. Gastrointestinal manifestations of CMA are often non-IgE mediated and clinical response to cow's milk free diet is not a proof of immune system involvement. Neither for non-IgE CMA nor for GERD there is a specific symptom or diagnostic test. Oral food challenge, esophageal pH impedance and endoscopy are recommended investigations for a correct clinical classification but they are not always feasible in all infants. As a consequence of the diagnostic difficulty, both over- and under- diagnosis of CMA or GERD may occur. Quite frequently acid inhibitors are empirically started. The aim of this review is to critically update the current knowledge of both conditions during infancy. A practical stepwise approach is proposed to help health care providers to manage infants presenting with persistent regurgitation, vomiting, crying or distress and to solve the clinical dilemma between GERD or CMA.

Noncanonical NF-κB signaling and the essential kinase NIK modulate crucial features associated with eosinophilic esophagitis pathogenesis

Eosinophilic esophagitis (EoE) is an allergic disease of the esophagus driven by T cell and eosinophil responses to dietary allergens, resulting in chronic mucosal inflammation. Few spontaneous animal models of esophageal eosinophilia exist, with most studies relying on artificial sensitization procedures. NF-κB-inducing kinase (NIK; MAP3K14) is a key signaling molecule of the noncanonical NF-κB (NFKB1) pathway, an alternative signaling cascade producing chemokines involved in lymphoid stroma development and leukocyte trafficking. Nik-/- mice have been shown to develop a hypereosinophilic syndrome in peripheral blood and major filtering organs; however, the gastrointestinal mucosa of these mice has not been well characterized. We show that Nik-/- mice develop significant, localized eosinophilic esophagitis that mimics human EoE, including features such as severe eosinophil accumulation, degranulation, mucosal thickening, fibrosis and basal cell hyperplasia. The remainder of the GI tract, including the caudal stomach, small intestine and colon, in mice with active EoE are unaffected, also similar to human patients. Gene expression patterns in esophageal tissue of Nik-/- mice mimics human EoE, with thymic stromal lymphopoetin (TSLP) in particular also elevated at the protein level. In gene expression data sets from human biopsy specimens, we further show that many genes associated with noncanonical NF-κB signaling are significantly dysregulated in EoE patients, most notably a paradoxical upregulation of NIK itself with concurrent upregulation of powerful protein-level destabilizers of NIK. These findings suggest that Nik-/- mice could be useful as a spontaneous model of specific features of EoE and highlight a novel role for noncanonical NF-κB signaling in human patients.

A Review of the Novel Application and Potential Adverse Effects of Proton Pump Inhibitors

Proton pump inhibitors (PPIs) are known as a class of pharmaceutical agents that target H⁺/K⁺-ATPase, which is located in gastric parietal cells. PPIs are widely used in the treatment of gastric acid-related diseases including peptic ulcer disease, erosive esophagitis and gastroesophageal reflux disease, and so on. These drugs present an excellent safety profile and have become one of the most commonly prescribed drugs in primary and specialty care. Except for gastric acid-related diseases, PPIs can also be used in the treatment of Helicobacter pylori infection, viral infections, respiratory system diseases, cancer and so on. Although PPIs are mainly used short term in patients with peptic ulcer disease, nowadays these drugs are increasingly used long term, and frequently for a lifetime, for instance in patients with typical or atypical symptoms of gastroesophageal reflux disease and in NSAID or aspirin users at risk of gastrotoxicity and related complications including hemorrhage, perforation and gastric outlet obstruction. Long-term use of PPIs may lead to potential adverse effects, such as osteoporotic fracture, renal damage, infection (pneumonia and clostridium difficile infection), rhabdomyolysis, nutritional deficiencies (vitamin B12, magnesium and iron), anemia and thrombocytopenia. In this article, we will review some novel uses of PPIs in other fields and summarize the underlying adverse reactions.

High Prevalence of Response to Proton-pump Inhibitor Treatment in Children With Esophageal Eosinophilia

OBJECTIVES

Proton-pump inhibitor-responsive esophageal eosinophilia is a newly recognized entity with an unclear prevalence in children, as only retrospective data are available. The aim of this study was to determine the prevalence and clinical features of proton-pump inhibitor-responsive esophageal eosinophilia in children.

METHODS

This prospective study enrolled patients with esophageal symptoms and esophageal eosinophilic counts as 15 or more than 15 eos/hpf (eosinophils per high-power field). Children received treatment with esomeprazole 1 mg · kg per dose twice daily for 8 weeks and the endoscopy was repeated. Complete response to proton-pump inhibitor (PPI) was defined as 5 or less than 5 eos/hpf, and a partial response as >5 and <15 eos/hpf in post-treatment biopsies.

RESULTS

Fifty-one children (74.5% boys) were included. Histological response was observed in 35 children (68.6%): 24 children (47%) had a complete response and 11 children (21.6%) had a partial response. Only 16 children (31.4%) were diagnosed with eosinophilic esophagitis (EoE). There were no differences in history of atopy, allergy tests, pH study results, and endoscopic scores. Clinical symptoms were similar, with the exception of food impaction, which was more frequent in children with EoE (56.2% vs 20%, P = 0.01). The mean pretreatment peak eosinophil count was higher in patients with EoE (74.8 ± 36.2 vs 46.3 ± 30.7, P = 0.007). Eleven of the 14 patients (78.6%) on a lower PPI treatment maintenance dose remained in clinicopathologic remission at 1-year follow-up.

CONCLUSIONS

A significant proportion of children with esophageal eosinophilia responded to high dose PPI treatment. Clinical, endoscopic, and pH study results were similar, with exception of patients with EoE, who were more likely to experience food impaction and have higher esophageal eosinophil counts.

Recent discoveries and emerging therapeutics in eosinophilic esophagitis

Eosinophilic esophagitis (EoE) is an allergy-mediated disease culminating in severe eosinophilic inflammation and dysfunction of the esophagus. This chronic disorder of the esophagus causes significant morbidity, poor quality of life, and complications involving fibrosis and esophageal remodeling. Overlapping features between EoE and gastroesophageal reflux disease (GERD) pose great challenges to differentiating the two conditions, although the two disorders are not mutually exclusive. Recent findings suggest that the confounding condition proton pump inhibitor - responsive esophageal eosinophilia (PPI-REE) is likely a subset of EoE. Since PPIs have therapeutic properties that can benefit EoE, PPIs should be considered as a therapeutic option for EoE rather than a diagnostic screen to differentiate GERD, PPI-REE, and EoE. Other current treatments include dietary therapy, corticosteroids, and dilation. Immunomodulators and biologic agents might have therapeutic value, and larger trials are needed to assess efficacy and safety. Understanding the pathophysiology of EoE is critical to the development of novel therapeutics.