Environmental and infectious factors in eosinophilic esophagitis

Expression profiling identifies key genes and biological functions associated with eosinophilic esophagitis in human patients

Introduction

Eosinophilic Esophagitis (EoE) is a chronic allergic disease characterized by progressive inflammation of the esophageal mucosa. This chronic inflammatory disorder affects up to 50 per 100,000 individuals in the United States and Europe yet is limited in treatment options. While the transcriptome of EoE has been reported, few studies have examined the genetics among a cohort including both adult and pediatric EoE populations. To identify potentially overlooked biomarkers in EoE esophageal biopsies that may be promising targets for diagnostic and therapeutic development.

Methods

We used microarray analysis to interrogate gene expression using esophageal biopsies from EoE and Control subjects with a wide age distribution. Analysis of differential gene expression (DEGs) and prediction of impaired pathways was compared using conventional transcriptome analysis (TAC) and artificial intelligence-based (ADVAITA) programs. Principal Components Analysis revealed samples cluster by disease status (EoE and Control) irrespective of clinical features like sex, age, and disease severity.

Results

Global transcriptomic analysis revealed differential expression of several genes previously reported in EoE (CCL26, CPA3, POSTN, CTSC, ANO1, CRISP3, SPINK7). In addition, we identified differential expression of several genes from the MUC and SPRR families, which have been limited in previous reports.

Discussion

Our findings suggest that there is epithelial dysregulation demonstrated by DEGs that may contribute to impaired barrier integrity and loss of epidermal cell differentiation in EoE patients. These findings present two new gene families, SPRR and MUC, that are differentially expressed in both adult and pediatric EoE patients, which presents an opportunity for a future therapeutic target that would be useful in a large demographic of patients.

Mechanisms and clinical management of eosinophilic oesophagitis: an overview

Since the first description of eosinophilic oesophagitis (EoE) less than three decades ago, we have observed a striking increase in the number of patients diagnosed with EoE and the understanding of its clinical and immunopathogenic background. Nonetheless, a plethora of open questions await elucidation. In this Review, we discuss the current state of knowledge regarding the underlying mechanisms, particularly environmental factors and their interaction with genetic susceptibility. Subsequently, we discuss how to translate these factors into the diagnostic and therapeutic management of this chronic, immune-mediated disorder. Finally, we dissect the still long list of unmet needs, such as reasons for and handling refractory EoE and atypical clinical presentations. These open questions can guide us through future research steps and potentially foster reconsideration of the diagnostic guidelines of EoE.

Replication and meta-analyses nominate numerous eosinophilic esophagitis risk genes

BACKGROUND

Eosinophilic esophagitis (EoE) is an emerging, chronic, rare allergic disease associated with marked eosinophil accumulation in the esophagus. Previous genome-wide association studies have provided strong evidence for 3 genome-wide susceptibility loci.

OBJECTIVE

We sought to replicate known and suggestive EoE genetic risk loci and conduct a meta-analysis of previously reported data sets.

METHODS

An EoE-Custom single-nucleotide polymophism (SNP) Chip containing 956 candidate EoE risk single-nucleotide polymorphisms was used to genotype 627 cases and 365 controls. Statistical power was enhanced by adding 1959 external controls and performing meta-analyses with 2 independent EoE genome-wide association studies.

RESULTS

Meta-analysis identified replicated association and genome-wide significance at 6 loci: 2p23 (2 independent genetic effects) and 5q22, 10p14, 11q13, and 16p13. Seven additional loci were identified at suggestive significance (P < 10-6): 1q31, 5q23, 6q15, 6q21, 8p21, 17q12, and 22q13. From these risk loci, 13 protein-coding EoE candidate risk genes were expressed in a genotype-dependent manner. EoE risk genes were expressed in disease-relevant cell types, including esophageal epithelia, fibroblasts, and immune cells, with some expressed as a function of disease activity. The genetic risk burden of EoE-associated genetic variants was markedly larger in cases relative to controls (P < 10-38); individuals with the highest decile of genetic burden had greater than 12-fold risk of EoE compared with those within the lowest decile.

CONCLUSIONS

This study extends the genetic underpinnings of EoE, highlighting 13 genes whose genotype-dependent expression expands our etiologic understanding of EoE and provides a framework for a polygenic risk score to be validated in future studies.

Red Between the Lines: Evolution of Eosinophilic Esophagitis as a Distinct Clinicopathologic Syndrome

Eosinophilic esophagitis (EoE) is characterized by eosinophilic infiltration of the esophageal mucosa and symptoms of esophageal dysfunction, including dysphagia. While EoE is still considered a rare disease, in practice it seems that more and more cases are diagnosed every week, research in the field is exploding, and the pipeline for treatments contains multiple agents, some of which are quite far along the development pathway. After only scattered cases and small series were published in the late 1970s and 1980, Stephen Attwood, Thomas Smyrk, Tom DeMeester, and James Jones, published in Digestive Diseases and Sciences in 1993 a seminal report that described a clinicopathologic syndrome of esophageal eosinophilia with dysphagia. This review details the origins of this paper and compares and contrast what was observed then and what is known now about multiple aspects of EoE, including the clinical presentation, diagnosis, epidemiology, natural history, and treatments and outcomes. Moreover, it will highlight how the paper presaged a number of controversies in the field that have yet to be resolved, as well as foreshadowed the collaborative, multidisciplinary approach that has led to rapid advances.

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.

Assessing the Risk Factors for Refractory Eosinophilic Esophagitis in Children and Adults

Background

Up to one-third of the patients suffering from eosinophilic esophagitis (EoE) present a refractory form, as defined by nonresponsiveness in clinical, endoscopic, or histological assessment after first-line therapy. Several studies recently investigated which factors can influence the development of this disease, but very few analyzed the factors underlying refractory EoE.

Methods

Medical charts of patients affected by EoE were retrospectively evaluated. Phenotyping of patients was conducted according to demographic, clinical, histological, and treatment variables. Then, patients were divided into responder and nonresponder to therapy and distinguished among children and adults.

Results

Forty-five children and 35 adult EoE patients were included. In the pediatric population, female sex (p < 0.05) and a higher score of visual analogue scale (VAS) at the follow-up visit (p = 0.02) were significantly associated to the risk of refractory EoE. Among adults, statistical significance was reached for years of follow-up (p = 0.001), diagnostic delay (p = 0.03), use of antibiotics during infancy (p = 0.01), and food allergy (p = 0.04).

Conclusions

Our study highlighted female sex and a higher VAS score at the time of follow-up visits as risk factors for refractory EoE in children, while the risk factors in adults were identified as fewer years of follow-up, greater diagnostic delay, use of antibiotics during infancy, and food allergy.

New developments in patients with eosinophilic gastrointestinal diseases presented at the CEGIR/TIGERS Symposium at the 2018 American Academy of Allergy, Asthma & Immunology Meeting

The Consortium of Eosinophilic Gastrointestinal Diseases and the International Gastrointestinal Eosinophil Researchers organized a day-long symposium at the recent 2018 Annual Meeting of the American Academy of Allergy, Asthma & Immunology, which was coupled for the first time with the World Allergy Organization meeting to create an international platform. The symposium featured experts in many facets of eosinophilic gastrointestinal diseases, including allergy, immunology, gastroenterology, pathology, and nutrition, and was a well-attended event. The basic science, genetics, cellular immunology, and clinical features of the diseases, with a focus on epithelial, eosinophil, and mast cell responses, as well as current and emerging treatment options, were reviewed. Here we briefly review some of the highlights of the material presented at the meeting.

Low Prevalence of Biopsy-Proven Eosinophilic Esophagitis in Patients with Esophageal Food Impaction in Mexican Population

BACKGROUND

Eosinophilic esophagitis (EoE) is the most common cause of dysphagia and esophageal food impaction (EFI) in the USA, Western Europe, and Australia. In Mexico, the uncomplicated form of this disease is infrequent, and prevalence in patients with EFI is unknown.

AIMS

To determine the prevalence and causes of EFI, endoscopic and therapeutic aspects, and establish the prevalence of biopsy-proven EoE in patients with EFI.

METHODS

Diagnostic upper gastrointestinal endoscopy reports from January 2011 to December 2016 were retrospectively reviewed. Patients with therapeutic procedures, gastrointestinal hemorrhage, or non-food foreign body impaction were excluded. The number of patients with EFI was determined. Additionally, patients with esophageal biopsy were retained for EoE prevalence calculation. The diagnosis of EoE was defined with the presence of eosinophil infiltration count ≥ 15/high-power field with or without typical endoscopic abnormalities.

RESULTS

A total of 4700 reports of the same number of patients were selected; 2209 were males (47%) with a mean age of 57.6 ± 12.3 years (range 14-93). We identified 36 patients with EFI (0.76, 95% CI 0.51-1.01), 16 males (44.4%) with a mean age of 54.9 ± 19.7 (range 22-92). Esophageal biopsies were obtained in 17/36 (47.2%) cases. The diagnosis of EoE was confirmed in 2 patients (11.7%). Peptic stenosis was the most frequent cause of EFI.

CONCLUSIONS

EoE is an infrequent cause of EFI in the Mexican population (11.7%). EoE had the lowest prevalence compared to that reported in Caucasian populations. The prevalence of EFI was also low.

Prenatal, intrapartum, and postnatal factors are associated with pediatric eosinophilic esophagitis

BACKGROUND

Multiple lines of evidence point to the potential importance of early-life environmental factors in the rapid increase in the incidence of eosinophilic esophagitis (EoE), but potential exposures have not been extensively studied.

OBJECTIVE

We sought to assess the association between prenatal, intrapartum, and postnatal factors and the development of pediatric EoE using a case-control study.

METHODS

Patients with EoE were recruited from an existing registry at Cincinnati Children's Hospital Medical Center (CCHMC). Population-based community control subjects were identified from a separate CCHMC registry. Mothers of study subjects were contacted and completed a Web-based questionnaire. Crude and adjusted models were used to estimate associations.

RESULTS

Mothers of 127 cases and 121 control subjects were included. We observed a positive association between several early-life factors and EoE, including prenatal (maternal fever: adjusted odds ratio [aOR], 3.18; 95% CI, 1.27-7.98; preterm labor: aOR, 2.18; 95% CI, 1.06-4.48), intrapartum (cesarean delivery: aOR, 1.77; 95% CI, 1.01, 3.09), and infancy (antibiotic use: aOR, 2.30; 95% CI, 1.21-4.38; use of an acid suppressant: aOR, 6.05; 95% CI, 2.55-14.40) factors. We observed an inverse association between having a furry pet in infancy and EoE (aOR, 0.58; 95% CI, 0.34-0.97). No associations were observed for breast-feeding or maternal multivitamin or folic acid supplement use.

CONCLUSION

Early-life factors, including maternal fever, preterm labor, cesarean delivery, and antibiotic or acid suppressant use in infancy, were associated with risk of pediatric EoE; having a pet in the home was protective. These results add to growing evidence that implicate early-life exposures in EoE pathogenesis.

Epidemiology and Natural History of Eosinophilic Esophagitis

Eosinophilic esophagitis (EoE) has emerged over the past 2 decades as a major cause of upper gastrointestinal morbidity. Over this time, the epidemiology of EoE has also rapidly evolved. EoE has transformed from a rare case-reportable condition to disease that is commonly encountered in the gastroenterology clinic, hospital emergency room, and endoscopy suite. The incidence and prevalence are increasing at rates that outpace increased disease recognition. Current incidence estimates range from 5 to 10 cases per 100,000, and current prevalence estimates range from 0.5 to 1 case per 1000. We review the data and potential reasons behind this increase, examine risk factors, and identify important areas for research into disease etiology. The article also discusses the progression of EoE from an inflammatory to fibrostenotic phenotype. An accurate view of the natural history of EoE is central to discussions with patients regarding disease prognosis and decisions about long-term use of medical, endoscopic, and diet therapies. Progressive remodelling appears to be gradual, but not universal, and the duration of untreated disease is the best predictor of stricture risk. Ultimately, prospective, long-term outcome studies focusing on multiple aspects of disease activity are needed to fully understand the natural history of EoE.

Eosinophilic Esophagitis: Pathophysiology and Definition

Eosinophilic esophagitis is an adaptive immune response to patient-specific antigens, mostly foods. Eosinophilic esophagitis is not solely IgE-mediated and is likely characterized by Th2 lymphocytes with an impaired esophageal barrier function. The key cytokines and chemokines are thymic stromal lymphopoeitin, interleukin-13, CCL26/eotaxin-3, and transforming growth factor-β, all involved in eosinophil recruitment and remodeling. Chronic food dysphagia and food impactions, the feared late complications, are related in part to dense subepithelial fibrosis, likely induced by interleukin-13 and transforming growth factor-β.

Creating a multi-center rare disease consortium - the Consortium of Eosinophilic Gastrointestinal Disease Researchers (CEGIR)

 Eosinophilic gastrointestinal disorders (EGIDs) affect various segments of the gastrointestinal tract. Since these disorders are rare, collaboration is essential to enroll subjects in clinical studies and study the broader population. The Rare Diseases Clinical Research Network (RDCRN), a program of the National Center for Advancing Translational Sciences (NCATS), funded the Consortium of Eosinophilic Gastrointestinal Disease Researchers (CEGIR) in 2014 to advance the field of EGIDs. CEGIR facilitates collaboration among various centers, subspecialties, patients, professional organizations and patient-advocacy groups and includes 14 clinical sites. It has successfully initiated two large multi-center clinical studies looking to refine EGID diagnoses and management. Several pilot studies are underway that focus on various aspects of EGIDs including novel therapeutic interventions, diagnostic and monitoring methods, and the role of the microbiome in pathogenesis. CEGIR currently nurtures five physician-scholars through a career training development program and has published more than 40 manuscripts since its inception. This review focuses on CEGIR's operating model and progress and how it facilitates a framework for exchange of ideas and stimulates research and innovation. This consortium provides a model for progress on other potential clinical areas.

Eosinophilic esophagitis. The North against the South? A bio-economic-social mechanistic approach and clinical implications

Eosinophilic esophagitis is a chronic antigen-mediated disease characterized by esophageal symptoms, esophageal eosinophilia, and the absence of response to proton pump inhibitors. It is the most frequent cause of dysphagia and food impaction in adults. Its incidence and prevalence is very high in the developed countries (USA, Europe, Australia), where its connotation is that of an emerging epidemic. While studies have been published with large case series in the developed countries, those published in Latin America are small or consist of isolated case reports. The differences in the prevalence of the disease between the developed and developing regions are unknown. Genetic or racial causes have been cited. Nevertheless, the epidemic nature of the disease suggests that environmental causes are the most powerful. Based on the published hypotheses, as well as on epidemiologic studies, the present review discusses some of the possible causes of the disparity in the prevalence of eosinophilic esophagitis between the two types of countries. The 'hygiene hypothesis' is reviewed, together with the possible relation of Helicobacter pylori, intestinal parasites, and modifications of the esophageal microbiota in patients with eosinophilic esophagitis. In reference to studies conducted in the United States, the clinical behavior and progression of eosinophilic esophagitis in Hispanics is reviewed and a possible predominant phenotype in Mexican and other Latin American patients is discussed. Finally, based on the above, an algorithm for studying the disease in the Latin American countries is proposed.

Genetic variations in the TLR3 locus are associated with eosinophilic esophagitis

Background

Eosinophilic esophagitis (EoE) is an antigen-driven disease mediated by an abnormal immune Th2 response.

Objective

The objective of this article is to investigate genes associated with regulating immune responses leading to disease susceptibility.

Methods

Twenty-seven tag single nucleotide polymorphisms (tSNPs) selected in five candidate genes (TLR3, TLR4, FOXP3, FLG and TSLP) were genotyped in 218 EoE patients and 376 controls. Skin prick tests were carried out in EoE patients with a panel of 17 aeroallergens and 22 plant- and animal-derived foods.

Results

Five tSNPs located in the TSLP locus and one tSNP located in the TLR3 locus were significantly associated with EoE. The interactions between TLR3 and TSLP loci were analyzed. TLR3+/TSLP- and TLR3-/TSLP+ individuals showed a significantly reduced susceptibility to EoE compared to TLR3-/TSLP- individuals (OR = 0.66, p = 0.036 and OR = 0.23, p = 0.00014, respectively). Likewise, TLR3+/TSLP+ individuals showed the most decreased susceptibility of developing EoE (OR = 0.16, p = 0.0001). However, the interaction gain attributed to the combination of both genes was negative (IG = -4.52%), which indicated redundancy or independent effect. Additionally, TLR3 locus was found to be associated with aeroallergen and food sensitization in EoE patients (OR = 9.67, p_c = 0.025 and OR = 0.53, p_c = 0.048, respectively).

Conclusion

TLR3 constitutes a novel genetic susceptibility locus for developing EoE, and the effects would be independent of TSLP.

Genetics of eosinophilic esophagitis

Eosinophilic esophagitis (EoE) is a chronic, allergic disease associated with marked mucosal eosinophil accumulation. EoE disease risk is multifactorial and includes environmental and genetic factors. This review will focus on the contribution of genetic variation to EoE risk, as well as the experimental tools and statistical methodology used to identify EoE risk loci. Specific disease-risk loci that are shared between EoE and other allergic diseases (TSLP, LRRC32) or unique to EoE (CAPN14), as well as Mendellian Disorders associated with EoE, will be reviewed in the context of the insight that they provide into the molecular pathoetiology of EoE. We will also discuss the clinical opportunities that genetic analyses provide in the form of decision support tools, molecular diagnostics, and novel therapeutic approaches.

Lymphocytic oesophagitis, eosinophilic oesophagitis and compound lymphocytic-eosinophilic oesophagitis I: histological and immunohistochemical findings

AIMS

To report four histological-immunohistochemical oesophagitis phenotypes.

METHODS

Oesophageal biopsies from 311 patients were stained with H&E and with CD3, a T cell marker. Additional immunohistochemical stains (n=413) were performed in 77 cases.

RESULTS

Four histological-immunohistochemical oesophagitis phenotypes were recorded: lymphocytic oesophagitis (LyE, ≥40 CD3+ lymphocytes/HPF in CD3 immunostain), eosinophilic oesophagitis (EoE, ≥15 eosinophils/HPF in H&E stain), lymphocytic infiltration (≤39 CD3+/HPF) and compound lymphocytic oesophagitis-eosinophilic oesophagitis (Co LyE-EoE). At index biopsy, 28.3% (n=88) had LyE, 21.2% (n=66) EoE, 10.6% (n=33) Co LyE-EoE and 39.9% (n=124) lymphocytic infiltration. A persistent oesophagitis phenotype was found in 42.5% (37/87) in the first follow-up biopsy, in 34.4% (21/61) in the second follow-up biopsy and in 48.1% (26/54) in the third follow-up biopsy. Using βF1 immunostain, two different surface T cell receptors were detected in LyE and Co Lye-EoE: one having ≥40 βF1+/HPF (βF1+ high) and the other having <39 βF1+/HPF (βF1+ low).

CONCLUSIONS

Based on the literature regarding the significance of intraepithelial lymphocytes (IELs) in the initiation of EoE, we submit that the IEL phenotypes in LyE might differ from those found in EoE as they were unable to elicit the same eosinophilic response. Recent studies disclosed that group 2 innate lymphocytes (ILC2s), enriched in EoE, remain undetected in CD3 immunostain as they lack surface markers for T, B, natural killer (NK) or NK T cells. If ILC2s also participate in the lymphocytic infiltration of EoE, then the frequency of cases with Co LyE-EoE here reported might have been much higher. The four oesophagitis phenotypes described are easy to recognise, provided that the dual staining procedure (H&E-CD3) is implemented.