The need for a reliable non-invasive diagnostic biomarker for eosinophilic oesophagitis

Eosinophilic esophagitis in the era of biologics

INTRODUCTION

Eosinophilic esophagitis (EoE) is a chronic inflammatory, disabling disorder characterized by prominent eosinophilic inflammation of the esophagus, leading to troublesome symptoms including dysphagia and food impaction. The natural history of EoE is poorly known, but it may lead to esophageal strictures. The therapeutic armamentarium is expected to grow in the near future, especially due to the availability of novel biological therapies targeting crucial inflammatory pathways of EoE.

AREAS COVERED

In this review, we discuss the main clinical features and natural history of EoE, focusing on the current therapeutic strategies, as well as past and current trials investigating biologics for its treatment.

EXPERT OPINION

Dupilumab has been the first approved biologic drug for the treatment of EoE; long-term studies assessing how it could change the natural history of EoE are awaited. Novel biological drugs or other molecules are currently under study and could change the current treatment algorithms in the near future. Proper drug positioning and long term 'exit strategies' are yet to be defined.

Diagnosis, management and therapeutic options for eosinophilic esophagitis

PURPOSE OF REVIEW

Eosinophilic esophagitis is a chronic and commonly evolving condition leading to relevant and potentially irreversible burden in terms of tissue damage and related functional impairment, thus significantly impacting on quality of life. The aim of the present review is to summarize the recent advances in terms of diagnostic work-up and pharmacological and nonpharmacological management of the disease, under the broader perspective of type 2 inflammation.

RECENT FINDINGS

Two major novelties have prompted an innovative approach to EoE. In terms of diagnosis, it has been proposed to dissect the disease heterogeneity in three endotypes, independent from tissue eosinophil number: EoEe1, characterized by normal appearing oesophagus; EoEe2, associated with type 2 inflammation and steroid-refractoriness; EoEe3, whose features include adult onset, a more fibro-stenotic aspect and loss of epithelial gene expression. Concerning treatment, two recently licensed drugs for EoE, oro-dispersible budesonide and dupilumab represent the first treatment options specifically developed for EoE and addressing EoE-related peculiar pathobiological features.

SUMMARY

In the era of precision medicine, managing EoE according to a phenotype-driven approach might be helpful in defining the best treatment options in the different disease forms or stages. In addition, exploring the coexistence or the previous occurrence of other type 2 conditions may suggest the opportunity to specifically target type 2 inflammation through biologic therapy. The complex EoE pathobiology combining inflammatory and functional features, both at organ and systemic level, requires a multidimensional approach relying on the strict integration of gastroenterologists and allergist-immunologists.

Circulating immunome fingerprint in eosinophilic esophagitis is associated with clinical response to proton pump inhibitor treatment

Objectives

The aim of the study was to characterize the circulating immunome of patients with EoE before and after proton pump inhibitor (PPI) treatment in order to identify potential non-invasive biomarkers of treatment response.

Methods

PBMCs from 19 healthy controls and 24 EoE patients were studied using a 39-plex spectral cytometry panel. The plasmacytoid dendritic cell (pDC) population was differentially characterized by spectral cytometry analysis and immunofluorescence assays in esophageal biopsies from 7 healthy controls and 13 EoE patients.

Results

Interestingly, EoE patients at baseline had lower levels of circulating pDC compared with controls. Before treatment, patients with EoE who responded to PPI therapy had higher levels of circulating pDC and classical monocytes, compared with non-responders. Moreover, following PPI therapy pDC levels were increased in all EoE patients, while normal levels were only restored in PPI-responding patients. Finally, circulating pDC levels inversely correlated with peak eosinophil count and pDC count in esophageal biopsies. The number of tissue pDCs significantly increased during active EoE, being even higher in non-responder patients when compared to responder patients pre-PPI. pDC levels decreased after PPI intake, being further restored almost to control levels in responder patients post-PPI.

Conclusions

We hereby describe a unique immune fingerprint of EoE patients at diagnosis. Moreover, circulating pDC may be also used as a novel non-invasive biomarker to predict subsequent response to PPI treatment.

Mononuclear cell composition and activation in blood and mucosal tissue of eosinophilic esophagitis

Introduction

Eosinophilic esophagitis (EoE) is a chronic, inflammatory, antigen-driven disease of the esophagus. Tissue EoE pathology has previously been extensively characterized by novel transcriptomics and proteomic platforms, however the majority of surface marker determination and screening has been performed in blood due to mucosal tissue size limitations. While eosinophils, CD4+ T cells, mast cells and natural killer (NK) T cells were previously investigated in the context of EoE, an accurate picture of the composition of peripheral blood mononuclear cells (PBMC) and their activation is missing.

Methods

In this study, we aimed to comprehensively analyze the composition of peripheral blood mononuclear cells and their activation using surface marker measurements with multicolor flow cytometry simultaneously in both blood and mucosal tissue of patients with active EoE, inactive EoE, patients with gastroesophageal reflux disease (GERD) and controls. Moreover, we set out to validate our data in co-cultures of PBMC with human primary esophageal epithelial cells and in a novel inducible mouse model of eosinophilic esophagitis, characterized by extensive IL-33 secretion in the esophagus.

Results

Our results indicate that specific PBMC populations are enriched, and that they alter their surface expression of activation markers in mucosal tissue of active EoE. In particular, we observed upregulation of the immunomodulatory molecule CD38 on CD4+ T cells and on myeloid cells in biopsies of active EoE. Moreover, we observed significant upregulation of PD-1 on CD4+ and myeloid cells, which was even more prominent after corticosteroid treatment. With co-culture experiments we could demonstrate that direct cell contact is needed for PD-1 upregulation on CD4+ T cells. Finally, we validated our findings of PD-1 and CD38 upregulation in an inducible mouse model of EoE.

Discussion

Herein we show significant alterations in the PBMC activation profile of patients with active EoE in comparison to inactive EoE, GERD and controls, which could have potential implications for treatment. To our knowledge, this study is the first of its kind expanding the multi-color flow cytometry approach in different patient groups using in vitro and in vivo translational models.

Global Incidence and Prevalence of Eosinophilic Esophagitis, 1976-2022: A Systematic Review and Meta-analysis

BACKGROUND AND AIMS

Owing to 2018 expanded diagnostic criteria for eosinophilic esophagitis (EoE) and thus a possible increase in diagnosis, previous studies on the global incidence and prevalence of EoE may need to be updated. We aimed to describe global, regional, and national trends in the incidence and prevalence of EoE from 1976 to 2022 and analyze their associations with geographic, demographic, and social factors through a systematic review.

METHODS

We searched the PubMed/MEDLINE, Embase, CINAHL, Google Scholar, and Cochrane databases from their inception dates to December 20, 2022, for studies that reported the incidence or prevalence of EoE in the general population. We calculated the global incidence and prevalence of EoE using pooled estimates with 95% confidence intervals (CIs) and performed subgroup analysis based on age, sex, race, geographical area, World Bank income group, and diagnostic criteria of EoE.

RESULTS

Forty studies met the eligibility criteria, including over 288 million participants and 147,668 patients with EoE from 15 countries across the five continents. The global pooled incidence and prevalence of EoE were 5.31 cases per 100,000 inhabitant-years (95% CI, 3.98-6.63; number of studies, 27; sample population, 42,191,506) and 40.04 cases per 100,000 inhabitant-years (95% CI, 31.10-48.98; number of studies, 20; sample population, 30,467,177), respectively. The pooled incidence of EoE was higher in high-income countries (vs low- or middle-income countries), males, and North America (vs Europe and Asia). The global prevalence of EoE followed a similar pattern. The pooled prevalence of EoE gradually increased from 1976 to 2022 (1976-2001; 8.18; 95% CI, 3.67-12.69 vs 2017-2022; 74.42; 95% CI, 39.66-109.19 cases per 100,000 inhabitant-years).

CONCLUSIONS

The incidence and prevalence of EoE have increased substantially and vary widely across the world. Further research is needed to evaluate the incidence and prevalence of EoE in Asia, South America, and Africa.

Dietary Strategies in Adult Patients with Eosinophilic Esophagitis: A State-of-the-Art Review

Allergen-free diets are a specific and effective anti-inflammatory therapy for eosinophilic esophagitis. They should be carried out by a multidisciplinary team to reduce side effects and improve adherence. According to recent guidelines and expert opinions, empirical diets with a reduced number of eliminated food categories and a step-up approach are the most encouraged strategy to reduce the number of endoscopies to identify food trigger(s) and maximize clinical results and adherence. Despite the fact that allergy testing-based diets are not recommended at a population level, geographical sensitization patterns may play a role in some patients in specific areas, such as in Southern and Central Europe.

Blood-Based Biomarkers for Eosinophilic Esophagitis and Concomitant Atopic Diseases: A Look into the Potential of Extracellular Vesicles

Eosinophilic esophagitis (EoE) is a chronic, Th2-inflammatory disease of the esophagus that can severely affect food intake. Currently, diagnosis and assessing response to treatment of EoE is highly invasive and requires endoscopy with esophageal biopsies. Finding non-invasive and accurate biomarkers is important for improving patient well-being. Unfortunately, EoE is usually accompanied by other atopies, which make it difficult to identify specific biomarkers. Providing an update of circulating EoE biomarkers and concomitant atopies is therefore timely. This review summarizes the current knowledge in EoE blood biomarkers and two of its most common comorbidities, bronchial asthma (BA) and atopic dermatitis (AD), focusing on dysregulated proteins, metabolites, and RNAs. It also revises the current knowledge on extracellular vesicles (EVs) as non-invasive biomarkers for BA and AD, and concludes with the potential use of EVs as biomarkers in EoE.

Primary eosinophilic gastrointestinal disorders and allergy: Clinical and therapeutic implications

Primary eosinophilic gastrointestinal disorders (EGID) are increasingly prevalent, immune‐mediated, chronic conditions which primarily affect pediatric and young adult patients, leading to substantial disease burden, and poor quality of life. EGID may either involve single portions of the gastrointestinal tract (i.e., esophagus, stomach, small bowel, and colon) or a combination. Their strong association with allergic disorders has been recently recognized, and although their shared pathophysiological basis remains partly elusive, this feature greatly impacts the diagnostic and treatment work‐up. We herein critically discuss the current knowledge on the association of EGID and allergic disorders, including atopic dermatitis, allergic rhinitis, allergic asthma, and food or drug allergy. In particular, we reviewed the literature focusing on their epidemiology, pathophysiological basis and mechanisms, and diagnostic strategies. Finally, we discuss the currently ongoing clinical trials targeting EGID and allergic diseases, including, among others the monoclonal antibodies dupilumab, mepolizumab, benralizumab, and lirentelimab.