Neuroimmune interplay during type 2 inflammation: Symptoms, mechanisms, and therapeutic targets in atopic diseases

Type 2 inflammation is characterized by overexpression and heightened activity of type 2 cytokines, mediators, and cells that drive neuroimmune activation and sensitization to previously subthreshold stimuli. The consequences of altered neuroimmune activity differ by tissue type and disease; they include skin inflammation, sensitization to pruritogens, and itch amplification in atopic dermatitis and prurigo nodularis; airway inflammation and/or hyperresponsiveness, loss of expiratory volume, airflow obstruction and increased mucus production in asthma; loss of sense of smell in chronic rhinosinusitis with nasal polyps; and dysphagia in eosinophilic esophagitis. We describe the neuroimmune interactions that underlie the various sensory and autonomic pathologies in type 2 inflammatory diseases and present recent advances in targeted treatment approaches to reduce type 2 inflammation and its associated symptoms in these diseases. Further research is needed to better understand the neuroimmune mechanisms that underlie chronic, sustained inflammation and its related sensory pathologies in diseases associated with type 2 inflammation.

Persistent esophageal changes after histologic remission in eosinophilic esophagitis

BACKGROUND

Eosinophilic esophagitis (EoE) is characterized by persistent or relapsing allergic inflammation, and both clinical and histologic features of esophageal inflammation persist over time in most individuals. Mechanisms contributing to EoE relapse are not understood, and chronic EoE-directed therapy is therefore required to prevent long-term sequelae.

OBJECTIVE

We investigated whether EoE patients in histologic remission have persistent dysregulation of esophageal gene expression.

METHODS

Esophageal biopsy samples from 51 pediatric and 52 adult subjects with EoE in histopathologic remission (<15 eosinophils per high-power field [eos/hpf]) and control (48 pediatric and 167 adult) subjects from multiple institutions were subjected to molecular profiling by the EoE diagnostic panel, which comprises a set of 94 esophageal transcripts differentially expressed in active EoE.

RESULTS

Defining remission as <15 eos/hpf, we identified 51 and 32 differentially expressed genes in pediatric and adult EoE patients compared to control individuals, respectively (false discovery rate < 0.05). Using the stringent definition of remission (0 eos/hpf), the adult and pediatric cohorts continued to have 18 and 25 differentially expressed genes (false discovery rate < 0.05). Among 6 shared genes between adults and children, CDH26 was upregulated in both children and adults; immunohistochemistry demonstrated increased cadherin 26 staining in the epithelium of EoE patients in remission compared to non-EoE controls. In the adult cohort, POSTN expression correlated with the endoscopic reference system score (Spearman r = 0.35, P = .011), specifically correlating with the rings' endoscopic reference system subscore (r = 0.53, P = .004).

CONCLUSION

We have identified persistent EoE-associated esophageal gene expression in patients with disease in deep remission. These data suggest potential inflammation-induced epigenetic mechanisms may influence gene expression during remission in EoE and provide insight into possible mechanisms that underlie relapse in EoE.

Common and disparate clinical presentations and mechanisms in different eosinophilic gastrointestinal diseases

Eosinophilic gastrointestinal diseases (EGIDs) are a group of diseases characterized by selective eosinophil infiltration of the gastrointestinal (GI) tract in the absence of other causes of eosinophilia. These diseases are generally driven by type 2 inflammation, often in response to food allergen exposure. Among all EGIDs, the clinical presentation often includes a history of atopic disease with a variety of GI symptoms. EGIDs are traditionally separated into eosinophilic esophagitis (EoE) and non-EoE EGIDs. EoE is relatively better understood and now associated with clinical guidelines and 2 US Food and Drug Administration-approved treatments, whereas non-EoE EGIDs are rarer and less well-understood diseases without US Food and Drug Administration-approved treatments. Non-EoE EGIDs are further subclassified by the area of the GI tract that is involved; they comprise eosinophilic gastritis, eosinophilic enteritis (including eosinophilic duodenitis), and eosinophilic colitis. As with other GI disorders, the disease presentations and mechanisms differ depending on the involved segment of the GI tract; however, the differences between EoE and non-EoE EGIDs extend beyond which GI tract segment is involved. The aim of this article is to summarize the commonalities and differences between the clinical presentations and disease mechanisms for EoE and non-EoE EGIDs.

Machine Learning Based Identification and Characterization of Mast Cells in Eosinophilic Esophagitis

BACKGROUND

Eosinophilic esophagitis (EoE) is diagnosed and monitored using esophageal eosinophil levels; however, EoE also exhibits a marked, understudied esophageal mastocytosis.

OBJECTIVE

Using machine learning, we localized and characterized esophageal mast cells to decipher their potential role in disease pathology.

METHODS

Esophageal biopsy samples (EoE, control) were stained for mast cells by anti-tryptase and imaged using immunofluorescence; high-resolution whole tissue images were digitally assembled. Machine learning software was trained to identify, enumerate, and characterize mast cells, designated Mast Cell-Artificial Intelligence (MC-AI).

RESULTS

MC-AI enumerated cell counts with high accuracy. During active EoE, epithelial mast cells increased and lamina propria (LP) mast cells decreased. In controls and EoE remission patients, papillae had the highest mast cell density and negatively correlated with epithelial mast cell density. Mast cell density in the epithelium and papillae correlated with the degree of epithelial eosinophilic inflammation, basal zone hyperplasia, and LP fibrosis. MC-AI detected greater mast cell degranulation in the epithelium, papillae, and LP in EoE patients compared with control individuals. Mast cells were localized further from the basement membrane in active EoE than EoE remission and control individuals but were closer than eosinophils to the basement membrane in active EoE.

CONCLUSION

Using MC-AI, we identified a distinct population of homeostatic esophageal papillae mast cells; during active EoE, this population decreases, undergoes degranulation, negatively correlates with epithelial mast cell levels, and significantly correlates with distinct histologic features. Overall, MC-AI provides a means to understand the potential involvement of mast cells in EoE and other disorders.

Impact of the COVID-19 Pandemic on People Living With Rare Diseases and Their Families: Results of a National Survey

BACKGROUND

With more than 103 million cases and 1.1 million deaths, the COVID-19 pandemic has had devastating consequences for the health system and the well-being of the entire US population. The Rare Diseases Clinical Research Network funded by the National Institutes of Health was strategically positioned to study the impact of the pandemic on the large, vulnerable population of people living with rare diseases (RDs).

OBJECTIVE

This study was designed to describe the characteristics of COVID-19 in the RD population, determine whether patient subgroups experienced increased occurrence or severity of infection and whether the pandemic changed RD symptoms and treatment, and understand the broader impact on respondents and their families.

METHODS

US residents who had an RD and were <90 years old completed a web-based survey investigating self-reported COVID-19 infection, pandemic-related changes in RD symptoms and medications, access to care, and psychological impact on self and family. We estimated the incidence of self-reported COVID-19 and compared it with that in the US population; evaluated the frequency of COVID-19 symptoms according to self-reported infection; assessed infection duration, complications and need for hospitalization; assessed the influence of the COVID-19 pandemic on RD symptoms and treatment, and whether the pandemic influenced access to care, special food and nutrition, or demand for professional psychological assistance.

RESULTS

Between May 2, 2020, and December 15, 2020, in total, 3413 individuals completed the survey. Most were female (2212/3413, 64.81%), White (3038/3413, 89.01%), and aged ≥25 years (2646/3413, 77.53%). Overall, 80.6% (2751/3413) did not acquire COVID-19, 2.08% (71/3413) acquired it, and 16.58% (566/3413) did not know. Self-reported cases represented an annual incidence rate of 2.2% (95% CI 1.7%-2.8%). COVID-19 cases were more than twice the expected (71 vs 30.3; P<.001). COVID-19 was associated with specific symptoms (loss of taste: odds ratio [OR] 38.9, 95% CI 22.4-67.6, loss of smell: OR 30.6, 95% CI 17.7-53.1) and multiple symptoms (>9 symptoms vs none: OR 82.5, 95% CI 29-234 and 5-9: OR 44.8, 95% CI 18.7-107). Median symptom duration was 16 (IQR 9-30) days. Hospitalization (7/71, 10%) and ventilator support (4/71, 6%) were uncommon. Respondents who acquired COVID-19 reported increased occurrence and severity of RD symptoms and use or dosage of select medications; those who did not acquire COVID-19 reported decreased occurrence and severity of RD symptoms and use of medications; those who did not know had an intermediate pattern. The pandemic made it difficult to access care, receive treatment, get hospitalized, and caused mood changes for respondents and their families.

CONCLUSIONS

Self-reported COVID-19 was more frequent than expected and was associated with increased prevalence and severity of RD symptoms and greater use of medications. The pandemic negatively affected access to care and caused mood changes in the respondents and family members. Continued surveillance is necessary.

Impact of climate change on immune responses and barrier defense

Climate change is not just jeopardizing the health of our planet but is also increasingly affecting our immune health. There is an expanding body of evidence that climate-related exposures such as air pollution, heat, wildfires, extreme weather events, and biodiversity loss significantly disrupt the functioning of the human immune system. These exposures manifest in a broad range of stimuli, including antigens, allergens, heat stress, pollutants, microbiota changes, and other toxic substances. Such exposures pose a direct and indirect threat to our body's primary line of defense, the epithelial barrier, affecting its physical integrity and functional efficacy. Furthermore, these climate-related environmental stressors can hyperstimulate the innate immune system and influence adaptive immunity-notably, in terms of developing and preserving immune tolerance. The loss or failure of immune tolerance can instigate a wide spectrum of noncommunicable diseases such as autoimmune conditions, allergy, respiratory illnesses, metabolic diseases, obesity, and others. As new evidence unfolds, there is a need for additional research in climate change and immunology that covers diverse environments in different global settings and uses modern biologic and epidemiologic tools.

Systematic identification of genotype-dependent enhancer variants in eosinophilic esophagitis

Eosinophilic esophagitis (EoE) is a rare atopic disorder associated with esophageal dysfunction, including difficulty swallowing, food impaction, and inflammation, that develops in a small subset of people with food allergies. Genome-wide association studies (GWASs) have identified 9 independent EoE risk loci reaching genome-wide significance (p < 5 × 10-8) and 27 additional loci of suggestive significance (5 × 10-8 < p < 1 × 10-5). In the current study, we perform linkage disequilibrium (LD) expansion of these loci to nominate a set of 531 variants that are potentially causal. To systematically interrogate the gene regulatory activity of these variants, we designed a massively parallel reporter assay (MPRA) containing the alleles of each variant within their genomic sequence context cloned into a GFP reporter library. Analysis of reporter gene expression in TE-7, HaCaT, and Jurkat cells revealed cell-type-specific gene regulation. We identify 32 allelic enhancer variants, representing 6 genome-wide significant EoE loci and 7 suggestive EoE loci, that regulate reporter gene expression in a genotype-dependent manner in at least one cellular context. By annotating these variants with expression quantitative trait loci (eQTL) and chromatin looping data in related tissues and cell types, we identify putative target genes affected by genetic variation in individuals with EoE. Transcription factor enrichment analyses reveal possible roles for cell-type-specific regulators, including GATA3. Our approach reduces the large set of EoE-associated variants to a set of 32 with allelic regulatory activity, providing functional insights into the effects of genetic variation in this disease.

Aryl hydrocarbon receptor and IL-13 signaling crosstalk in human keratinocytes and atopic dermatitis

Introduction

Atopic dermatitis (AD) is an allergic skin disease mediated by skin barrier impairment and IL-13-driven immune response. Activation of the aryl hydrocarbon receptor (AHR) has shown promise in early clinical trials for AD; however, the mechanism by which AHR partially ameliorates AD is not well known.

Methods

Gene expression data from human biopsies were analyzed, and compared to gene expression from RNA-sequencing in our in-vitro HaCaT cell model system. Western blot, ELISA qRT-PCR were used to further explore the relationship between AHR and IL-13 signaling in HaCaT cells.

Results

The AHR target gene CYP1A1 was decreased in lesional skin compared with healthy control skin (p = 4.30 × 10-9). Single-cell RNA sequencing (scRNAseq) demonstrated increased AHR expression (p < 1.0 × 10-4) and decreased CYP1A1 expression in lesional AD keratinocytes compared with healthy control keratinocytes (p < 0.001). Activation of AHR by AHR agonists in HaCaT cells reversed IL-13-dependent gene expression of several key genes in AD pathogenesis, most notably the eosinophil chemoattractant CCL26 (eotaxin-3). Differentially expressed genes in keratinocytes of patients with AD substantially overlapped with genes regulated by AHR agonists from HaCaT cells by RNAseq, but in reverse direction. Mechanistically, there was evidence for direct transcriptional effects of AHR; AHR binding motifs were identified in the differentially expressed genes from lesional AD keratinocytes compared to control keratinocytes, and AHR activation did not modify IL-13-dependent signal transducer and activator of transcription 6 (STAT6) translocation to the nucleus.

Discussion

Together, these data suggest that the AHR pathway is dysregulated in AD and that AHR modulates IL-13 downstream signaling in keratinocytes through genome-wide, transcriptional regulatory effects.

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.

Eosinophil Involvement Outside the Esophagus in Eosinophilic Esophagitis

Eosinophilic gastrointestinal diseases (EGIDs) are chronic, immune-mediated disorders, characterized clinically by gastrointestinal (GI) symptoms and histologically by eosinophil-predominant infiltration in ≥1 GI tract segment.1 A recent, international consensus by 91 experts proposed a new framework for EGID nomenclature to establish updated terms, designations, and conventions.2 Although this framework offers a standardized starting point for the field, debate is ongoing regarding the appropriate terminology for cases involving multiple areas, such as "non-eosinophilic esophagitis (EoE) EGID and EoE" or "non-EoE EGID with esophageal involvement (EI)." Notably, in a survey of these experts, 61% agreed with the later term "non-EoE EGID with EI," because EoE is isolated to the esophagus by current diagnostic criteria.3 However, limited molecular and pathogenic data exist to support the distinction. Furthermore, disease burden of symptoms and comorbidities generally is higher in non-EoE EGIDs than EoE.4 Presently, there is no screen to predict non-EoE EGID concomitance in EoE; therefore, decision-making to further explore other GI segment involvement is clinically challenging. We aimed to answer 2 fundamental questions in the field (Figure 1A): Is there a shared or distinct pathogenesis between patients with isolated EoE and non-EoE EGIDs with EI as assessed by patient characteristics and molecular profiles? Can we predict concomitant non-EoE EGIDs when EoE exists? Herein, we report a similar molecular signature between EoE and EI and a potential predictive model to identify concomitant non-EoE EGIDs in patients with EoE.

Breakthroughs in understanding and treating eosinophilic gastrointestinal diseases presented at the CEGIR/TIGERs Symposium at the 2022 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 2022 Annual Meeting of the American Academy of Allergy, Asthma & Immunology. The symposium featured a review of recent discoveries in the basic biology and pathogenesis of eosinophilic gastrointestinal diseases (EGIDs) in addition to advances in our understanding of the clinical features of EGIDs. Diagnostic and management approaches were reviewed and debated, and clinical trials of emerging therapies were highlighted. Herein, we briefly summarize the breakthrough discoveries in EGIDs.

Efficacy and safety of dupilumab up to 52 weeks in adults and adolescents with eosinophilic oesophagitis (LIBERTY EoE TREET study): a multicentre, double-blind, randomised, placebo-controlled, phase 3 trial

BACKGROUND

Long-term management options that specifically target the underlying inflammation in eosinophilic oesophagitis are needed. Dupilumab blocks the shared receptor component for interleukin (IL)-4/IL-13; we aimed to assess its long-term efficacy and safety in adults and adolescents with eosinophilic oesophagitis enrolled in part B of the LIBERTY EoE TREET study who continued to part C (part B-C).

METHODS

LIBERTY EoE TREET was a three-part, double-blind, randomised, placebo-controlled, phase 3 study conducted at 65 hospitals and private clinics across ten countries in Australia, Canada, Europe, and the USA. Adults or adolescents (aged ≥12 years) with a diagnosis of eosinophilic oesophagitis by endoscopic biopsy (peak oesophageal intraepithelial eosinophil count ≥15 eosinophils per high-power field [eos/hpf]) from at least one oesophageal region despite 8 weeks of high-dose proton-pump inhibitors (PPIs) and a Dysphagia Symptom Questionnaire (DSQ) score of at least 10 at baseline were eligible. In part B, patients were randomly (1:1:1) assigned to receive subcutaneous dupilumab 300 mg either weekly or every 2 weeks or weekly placebo until week 24. Randomisation was done centrally by interactive voice response system/web response system (IVRS/IWRS) in blocks and stratified according to age (<18 years vs ≥18 years) and use of PPI at randomisation (yes vs no). Patients, study sponsors, and investigators involved in the study were masked to the randomisation outcome. Eligible patients who received placebo in part B and continued to part C were randomly assigned again (1:1) to either weekly dupilumab (placebo/weekly dupilumab group) or dupilumab every 2 weeks (placebo/dupilumab every 2 weeks), with matching placebo alternating with dupilumab doses. Patients who were randomly assigned to one of the dupilumab dose regimens in part B remained on the same regimen in part C for an additional 28 weeks (weekly dupilumab/weekly dupilumab group or dupilumab every 2 weeks/dupilumab every 2 weeks group). Treatment assignment in part C was managed by IVRS/IWRS to maintain blinding of treatment assignment in part B. The primary endpoint of this trial has been reported; here, we report the week 52 outcomes of part B-C. Efficacy and safety analyses were done in the part C safety-analysis set, which included all patients who were randomised in part B, entered part C, and received any study drug in part C. This completed trial is registered with ClinicalTrials.gov, number NCT03633617.

FINDINGS

Between Aug 12, 2019, and March 11, 2021, 240 patients were randomly assigned into part B, of whom 227 (74 in placebo group, 74 in weekly dupilumab group, and 79 in dupilumab every 2 weeks group) continued into part B-C and were included in the current analysis. 37 patients switched from placebo to weekly dupilumab, and 37 from placebo to dupilumab every 2 weeks; 74 patients continued on weekly dupilumab and 79 continued on dupilumab every 2 weeks. Of the patients who entered part B-C, 75 (33%) were adolescents, 145 (64%) male, 82 (36%) female, and 206 (91%) White. At week 52, 55 (85%) patients in the weekly dupilumab/weekly dupilumab group, 25 (68%) in the placebo/weekly dupilumab group, 54 (74%) in the every 2 weeks dupilumab/every 2 weeks dupilumab group, and 23 (72%) in the placebo/every 2 weeks dupilumab group achieved a peak oesophageal intraepithelial eosinophil count of 6 eos/hpf or less. Mean percent change from part B baseline in peak eosinophil count was -95·9% (95% CI -96·9 to -94·9) in the weekly dupilumab/weekly dupilumab group, -84·2% (-98·3 to -70·2) in the placebo/weekly dupilumab group, -84·8% (-94·3 to -75·2) in the every 2 weeks dupilumab/every 2 weeks dupilumab group, and -91·2% (-95·9 to -86·5) in the placebo/every 2 weeks dupilumab group at week 52. At week 52, mean change from part B baseline in eosinophilic oesophagitis Histology Scoring System (HSS) grade score was -1·0 point (95% CI -1·1 to -0·9) in the weekly dupilumab/weekly dupilumab group and -0·9 points (-1·0 to -0·8) in the placebo/weekly dupilumab group; mean change in eosinophilic oesophagitis HSS stage score was -0·9 points (-1·0 to -0·8) in the weekly dupilumab/weekly dupilumab group and -0·9 points (-1·0 to -0·8) in the placebo/weekly dupilumab group. Similar improvements were observed in the every 2 weeks dupilumab groups. Mean absolute change from part B baseline in DSQ score was -30·3 points (95% CI -34·5 to -26·1) in the weekly dupilumab/weekly dupilumab group, -27·3 points (-32·1 to -22·4) in the placebo/weekly dupilumab group, -20·9% (-25·4 to -16·3) in the every 2 weeks dupilumab/every 2 weeks dupilumab group, and -23·7% (-29·1 to -18·3) in the placebo/every 2 weeks dupilumab group at week 52. Mean change from part B baseline in endoscopic reference score was -5·4 points (95% CI -6·1 to -4·6) in the weekly dupilumab/weekly dupilumab group, -6·1 points (-7·3 to -4·9) in the placebo/weekly dupilumab group, -5·2% (-6·0 to -4·4) in the every 2 weeks dupilumab/every 2 weeks dupilumab group, and -4·3% (-5·4 to -3·1) in the placebo/every 2 weeks dupilumab group at week 52. During part B-C, one (3%) patient in the placebo/weekly dupilumab group, one (1%) in the weekly dupilumab/weekly dupilumab group, and one (3%) in the placebo/every 2 weeks dupilumab group received rescue medication. One (3%) patient in the placebo/every 2 weeks dupilumab group and one (1%) in the dupilumab every 2 weeks/dupilumab every 2 weeks group underwent a rescue oesophageal dilation procedure. The most common treatment-emergent adverse events were injection-site reactions (ten [14%] in the weekly dupilumab/weekly dupilumab group and four [11%] in the placebo/weekly dupilumab group).

INTERPRETATION

Improvements in histological, symptomatic, endoscopic, and molecular features of eosinophilic oesophagitis observed after 24 weeks of weekly dupilumab treatment were maintained or continued to improve to week 52. These findings reinforce the importance of weekly dupilumab, rather than every 2 weeks, for the improvement of symptoms in adults and adolescents with eosinophilic oesophagitis.

FUNDING

Sanofi and Regeneron Pharmaceuticals Inc.

A conversation on allergy: recognizing the past and looking to the future

Allergy is an ever-evolving group of disorders, which includes asthma, atopic dermatitis, rhinitis and food allergies and that currently affects over 1 billion people worldwide. This group of disorders has exploded in incidence since around the start of the 20th century, implying that genetics is not solely responsible for its development but that environmental factors have an important role. Here, Fabio Luciani and Jonathan Coquet, in their role as editors at Immunology & Cell Biology, asked nine prominent researchers in the field of allergy to define the term 'allergy', discuss the role of genetics and the environment, nominate the most important discoveries of the past decade and describe the best strategies to combat allergy at the population level going forward.

Machine Learning Based Identification and Characterization of Mast cells in Eosinophilic Esophagitis

Background

Eosinophilic esophagitis (EoE) is diagnosed and monitored using esophageal eosinophil levels; however, EoE also exhibits a marked, understudied esophageal mastocytosis.

Objective

Using machine learning, we localized and characterized esophageal mast cells to decipher their potential role in disease pathology.

Methods

Esophageal biopsy samples (EoE, control) were stained for mast cells by anti-tryptase and imaged using immunofluorescence; high-resolution whole tissue images were digitally assembled. Machine learning software was trained to identify, enumerate, and characterize mast cells, designated Mast Cell-Artificial Intelligence (MC-AI).

Results

MC-AI enumerated cell counts with high accuracy. During active EoE, epithelial mast cells increased and lamina propria (LP) mast cells decreased. In controls and EoE remission patients, papillae had the highest mast cell density and negatively correlated with epithelial mast cell density. Mast cell density in the epithelium and papillae correlated with the degree of epithelial eosinophilic inflammation, basal zone hyperplasia, and LP fibrosis. MC-AI detected greater mast cell degranulation in the epithelium, papillae, and LP in EoE patients compared with control individuals. Mast cells were localized further from the basement membrane in active EoE than EoE remission and controls individuals but were closer than eosinophils to the basement membrane in active EoE.

Conclusion

Using MC-AI, we identified a distinct population of homeostatic esophageal papillae mast cells; during active EoE, this population decreases, undergoes degranulation, negatively correlates with epithelial mast cell levels, and significantly correlates with distinct histologic features. Overall, MC-AI provides a means to understand the potential involvement of mast cells in EoE and other disorders.

Clinical Implication

We have developed a methodology for identifying, enumerating, and characterizing mast cells using artificial intelligence; this has been applied to decipher eosinophilic esophagitis and provides a platform approach for other diseases.

Capsule Summary

A machine learning protocol for identifying mast cells, designated Mast Cell-Artificial Intelligence, readily identified spatially distinct and dynamic populations of mast cells in EoE, providing a platform to better understand this cell type in EoE and other diseases.

Esophageal Epithelium and Lamina Propria Are Unevenly Involved in Eosinophilic Esophagitis

BACKGROUND & AIMS

The nature of the involvement of esophageal tissue in eosinophilic esophagitis (EoE) is unclear. We estimated the intrabiopsy site agreements of the EoE Histologic Scoring System (EoEHSS) scores for the grade (degree) and stage (extent) of involvement of the esophageal epithelial and lamina propria and examined if the EoE activity status influenced the intrabiopsy site agreement.

METHODS

Demographic, clinical, and EoEHSS scores collected as part of the prospective Outcome Measures for Eosinophilic Gastrointestinal Diseases Across Ages study were analyzed. A weighted Cohen's kappa agreement coefficient (k) was used to calculate the pairwise agreements for proximal:distal, proximal:middle, and middle:distal esophageal biopsy sites, separately for grade and stage scores, for each of the 8 components of EoEHSS. A k > 0.75 was considered uniform involvement. Inactive EoE was defined as fewer than 15 eosinophils per high-powered field.

RESULTS

EoEHSS scores from 1263 esophageal biopsy specimens were analyzed. The k for the stage of involvement of the dilated intercellular spaces across all 3 sites in inactive EoE was consistently greater than 0.75 (range, 0.87-0.99). The k for lamina propria fibrosis was greater than 0.75 across some of the biopsy sites but not across all 3. Otherwise, the k for all other features, for both grade and stage, irrespective of the disease activity status, was 0.75 or less (range, 0.00-0.74).

CONCLUSIONS

Except for the extent of involvement of dilated intercellular spaces in inactive EoE, the remaining epithelial features and lamina propria are involved unevenly across biopsy sites in EoE, irrespective of the disease activity status. This study enhances our understanding of the effects of EoE on esophageal tissue pathology.

TSLP shapes the pathogenic responses of memory CD4+ T cells in eosinophilic esophagitis

The cytokine thymic stromal lymphopoietin (TSLP) mediates type 2 immune responses, and treatments that interfere with TSLP activity are in clinical use for asthma. Here, we investigated whether TSLP contributes to allergic inflammation by directly stimulating human CD4+ T cells and whether this process is operational in eosinophilic esophagitis (EoE), a disease linked to variants in TSLP. We showed that about 10% of esophageal-derived memory CD4+ T cells from individuals with EoE and less than 3% of cells from control individuals expressed the receptor for TSLP and directly responded to TSLP, as determined by measuring the phosphorylation of STAT5, a transcription factor activated downstream of TSLP stimulation. Accordingly, increased numbers of TSLP-responsive memory CD4+ T cells were present in the circulation of individuals with EoE. TSLP increased the proliferation of CD4+ T cells, enhanced type 2 cytokine production, induced the increased abundance of its own receptor, and modified the expression of 212 genes. The epigenetic response to TSLP was associated with an enrichment in BATF and IRF4 chromatin-binding sites, and these transcription factors were induced by TSLP, providing a feed-forward loop. The numbers of circulating and esophageal CD4+ T cells responsive to TSLP correlated with the numbers of esophageal eosinophils, supporting a potential functional role for TSLP in driving the pathogenesis of EoE and providing the basis for a blood-based diagnostic test based on the extent of TSLP-induced STAT5 phosphorylation in circulating CD4+ T cells. These findings highlight the potential therapeutic value of TSLP inhibitors for the treatment of EoE.

The minichromosome maintenance complex drives esophageal basal zone hyperplasia

Eosinophilic esophagitis (EoE) is a chronic gastrointestinal disorder characterized by food antigen-driven eosinophilic inflammation and hyperproliferation of esophageal mucosa. By utilizing a large-scale, proteomic screen of esophageal biopsies, we aimed to uncover molecular drivers of the disease. Proteomic analysis by liquid chromatography-tandem mass spectrometry identified 402 differentially expressed proteins (DEPs) that correlated with the EoE transcriptome. Immune cell-related proteins were among the most highly upregulated DEPs in EoE compared with controls, whereas proteins linked to epithelial differentiation were primarily downregulated. Notably, in the inflamed esophageal tissue, all 6 subunits of the minichromosome maintenance (MCM) complex, a DNA helicase essential for genomic DNA replication, were significantly upregulated at the gene and protein levels. Furthermore, treating esophageal epithelial cells with a known inhibitor of the MCM complex (ciprofloxacin) blocked esophageal epithelial proliferation. In a murine model of EoE driven by overexpression of IL-13, ciprofloxacin treatment decreased basal zone thickness and reduced dilated intercellular spaces by blocking the transition of epithelial cells through the S-phase of the cell cycle. Collectively, a broad-spectrum proteomic screen has identified the involvement of the MCM complex in EoE and has highlighted MCM inhibitors as potential therapeutic agents for the disease.

Prospective study of an amino acid-based elemental diet in an eosinophilic gastritis and gastroenteritis nutrition trial

BACKGROUND

Eosinophilic gastritis/gastroenteritis (EoG/EoGE) are rare disorders with pathologic gastric and/or small intestinal eosinophilia lacking an approved therapy. An allergic mechanism is postulated but underexplored mechanistically and therapeutically.

OBJECTIVE

We evaluated the effectiveness of a food allergen-free diet (elemental formula) in controlling gastrointestinal eosinophilia in adult EoG/EoGE.

METHODS

Adults aged 18 to 65 years with histologically active EoG/EoGE (≥30 eosinophils per high-power field) in the stomach and/or duodenum and gastrointestinal symptoms within the month preceding enrollment were prospectively enrolled onto a single-arm clinical trial to receive elemental formula for 6 consecutive weeks. The primary end point was percentage of participants with complete histologic remission (<30 eosinophils per high-power field in both stomach and duodenum). Exploratory outcomes were improvement in symptoms, endoscopy results, blood eosinophilia, quality of life, Physician Global Assessment score, and EoG-relevant gastric transcriptome and microbiome.

RESULTS

Fifteen adults (47% male, average age 37.7 years, average symptom duration 8.8 years) completed the trial. Multi-gastrointestinal segment involvement affected 87%. All subjects had complete histologic remission in the stomach (P = .002) and duodenum (P = .001). Scores improved in overall PhGA (P = .002); EGREFS (P = .003); EGDP (P = .002); SODA pain intensity (P = .044), non-pain (P = .039), and satisfaction (P = .0024); and PROMIS depression (P = .0078) and fatigue (P = .04). Food reintroduction reversed these improvements. The intervention was well tolerated in 14 subjects, with 1 serious adverse event reported in 1 subject.

CONCLUSION

An amino acid-based elemental diet improves histologic, endoscopic, symptomatic, quality-of-life, and molecular parameters of EoG/EoGE; these findings and disease recurrence with food trigger reintroduction support a dominant role for food allergens in disease pathogenesis.

CLINICALTRIALS

gov Identifier: NCT03320369.

Recent Advances in the Treatment of Eosinophilic Esophagitis

Eosinophilic esophagitis is an increasingly common inflammatory allergic disease of the esophagus characterized by esophageal eosinophilia and symptoms of esophageal dysfunction. The therapeutic landscape has rapidly evolved for this emerging type 2 inflammatory disorder. We review traditional therapies including updates and expert opinions in addition to promising therapies on the horizon and the history of therapies that failed to meet end points and highlight knowledge gaps for future investigations.

Benralizumab for eosinophilic gastritis: a single-site, randomised, double-blind, placebo-controlled, phase 2 trial

BACKGROUND

In eosinophilic gastrointestinal diseases, the role of eosinophils in disease pathogenesis and the effect of eosinophil depletion on patient outcomes are unclear. Benralizumab, an eosinophil-depleting monoclonal antibody that targets the interleukin-5 receptor α, might eliminate gastric tissue eosinophils and improve outcomes in eosinophilic gastritis. We aimed to assess the efficacy and safety of benralizumab in patients with eosinophilic gastritis.

METHODS

We conducted a single-site, randomised, double-blind, placebo-controlled, phase 2 trial at Cincinnati Children's Hospital Medical Center (Cincinnati, OH, USA). Individuals aged 12-60 years with symptomatic, histologically active eosinophilic gastritis (peak gastric eosinophil count ≥30 eosinophils per high-power field [eos/hpf] in at least five hpfs) and blood eosinophilia (>500 eosinophils per μL [eos/μL]) were randomly assigned (1:1, block size of four) to benralizumab 30 mg or placebo, stratified by the use of glucocorticoids for gastric disease. Investigators, study staff, and study participants were masked to treatment assignment; statisticians were unmasked when analysing data. Treatments were administered subcutaneously once every 4 weeks for a 12-week double-blind period (three total injections). The primary endpoint was the proportion of patients who achieved histological remission (peak gastric eosinophil count <30 eos/hpf) at week 12. Key secondary endpoints were the changes from baseline to week 12 in peak gastric eosinophil count, blood eosinophil count, eosinophilic gastritis histology (total, inflammatory, and structural feature scores), Eosinophilic Gastritis Endoscopic Reference System (EG-REFS) score, and patient-reported outcome symptom measures (Severity of Dyspepsia Assessment [SODA] and Patient-Reported Outcome Measurement Information System [PROMIS] short-form questionnaire). After the 12-week double-blind period, patients were eligible for entry into two open-label extension (OLE) periods up to week 88, in which all patients received benralizumab. Efficacy was analysed in the intention-to-treat (ITT) population and safety was assessed in all patients who received at least one dose of study drug. The trial was registered on ClinicalTrials.gov, NCT03473977, and is completed.

FINDINGS

Between April 23, 2018, and Jan 13, 2020, 34 patients were screened, and 26 were subsequently randomly assigned to benralizumab (n=13) or placebo (n=13) and included in the ITT and safety populations (mean age 19·5 years [SD 7·3]; 19 [73%] male patients and seven [27%] female patients). At week 12, ten (77% [95% CI 50 to 92]) of 13 patients who received benralizumab and one (8% [1 to 33]) of 13 who received placebo achieved histological remission (difference 69 percentage points [95% CI 32 to 85]; p=0·0010). Changes from baseline to week 12 were significantly greater in the benralizumab group versus the placebo group for peak gastric eosinophil counts (mean -137 eos/hpf [95% CI -186 to -88] vs -38 eos/hpf [-94 to 18]; p=0·0080), eosinophilic gastritis histology total score (mean -0·31 [-0·42 to -0·20] vs -0·02 [-0·16 to 0·12]; p=0·0016), histology inflammatory score (mean -0·46 [-0·60 to -0·31] vs -0·04 [-0·22 to 0·13]; p=0·0006), and blood eosinophil counts (median -1060 eos/μL [IQR -1740 to -830] vs -160 eos/μL [-710 to 120]; p=0·0044). Changes were not significantly different between the groups for eosinophilic gastritis histology structural score (mean -0·07 [95% CI -0·19 to 0·05] vs 0·03 [-0·09 to 0·15]; p=0·23), EG-REFS score (mean -1·0 [-2·3 to 0·3] vs -0·5 [-2·0 to 1·0]; p=0·62), or in patient-reported outcomes (SODA and PROMIS). During the double-blind period, treatment-emergent adverse events occurred in 11 (85%) of 13 patients in the benralizumab group and six (46%) of 13 in the placebo group; the most common treatment-emergent adverse events were headache (six [46%] vs two [15%] patients), nausea (three [23%] vs two [15%]), and vomiting (two [15%] vs three [23%]). There were no treatment-related deaths. Two patients had serious adverse events (dizziness and rhabdomyolysis in one patient; aspiration in one patient) during the OLE periods, which were considered unrelated to study treatment.

INTERPRETATION

Benralizumab treatment induced histological remission, as defined by absence of tissue eosinophilia, in most patients with eosinophilic gastritis. However, the persistence of histological, endoscopic, and other features of the disease suggest a co-existing, eosinophil-independent pathogenic mechanism and the need for broader targeting of type 2 immunity.

FUNDING

AstraZeneca and the Division of Intramural Research (National Institute of Allergy and Infectious Diseases, US National Institutes of Health).

Local type 2 immunity in eosinophilic gastritis

BACKGROUND

Eosinophilic gastritis (EoG) associates with type 2 immunity. However, the type 2 cytokine cellular source, gastric T-cell composition, and gastric T-cell relationship (or relationships) with disease pathology remain understudied.

OBJECTIVE

We defined gastric T-cell populations and their association with histologic and endoscopic EoG pathology.

METHODS

Gastric biopsy samples (n = 6 EoG, n = 7 control) were subjected to histologic, endoscopic, and flow cytometry analyses. In a complementary cohort (n = 83 EoG), IL4, IL5, and IL13 mRNA levels were correlated with EoG pathologic parameters.

RESULTS

Gastric biopsy samples contained CD3+ T cells that were mainly CD8+; the CD8/CD4 ratio was comparable in EoG and control biopsy samples (5.7 ± 3.0 and 4.3 ± 0.6, respectively; P = .28). Gastric regulatory T (CD3+CD4+FOXP3+) and TH2 (CD3+CD4+GATA3+) cell levels were increased in EoG versus controls (2-fold, P < .05 and 10-fold, P < .001, respectively) and correlated with gastric eosinophil levels (r = 0.63, P < .05 and r = 0.85, P < .001, respectively), endoscopic pathology (r = 0.56, P < .01; r = 0.84, P < .001, respectively), and histopathology (r = 0.72, P < .01; r = 0.82, P < .01, respectively). Cytokine-positive, most notably IL-4+, TH2 cell levels strongly correlated with histologic and endoscopic scores (r = 0.82, P < .0001 and r = 0.78, P < .0001, respectively). In an independent EoG cohort (n = 83), bulk gastric IL4, IL5, and IL13 mRNA levels correlated with histologic score (r = 0.22, P < .005; r = 0.54, P < .0001; and r = 0.36, P < .0001, respectively) and endoscopic score (r = 0.27, P < .001; r = 0.40, P < .0001; and r = 0.35, P < .0001, respectively).

CONCLUSIONS

EoG is a TH2 cell-associated disease featuring increased gastric type 2 cytokine-producing CD3+CD4+GATA3+TH2 cells that strongly correlate with disease pathologies.

One-food versus six-food elimination diet therapy for the treatment of eosinophilic oesophagitis: a multicentre, randomised, open-label trial

BACKGROUND

Empirical elimination diets are effective for achieving histological remission in eosinophilic oesophagitis, but randomised trials comparing diet therapies are lacking. We aimed to compare a six-food elimination diet (6FED) with a one-food elimination diet (1FED) for the treatment of adults with eosinophilic oesophagitis.

METHODS

We conducted a multicentre, randomised, open-label trial across ten sites of the Consortium of Eosinophilic Gastrointestinal Disease Researchers in the USA. Adults aged 18-60 years with active, symptomatic eosinophilic oesophagitis were centrally randomly allocated (1:1; block size of four) to 1FED (animal milk) or 6FED (animal milk, wheat, egg, soy, fish and shellfish, and peanut and tree nuts) for 6 weeks. Randomisation was stratified by age, enrolling site, and gender. The primary endpoint was the proportion of patients with histological remission (peak oesophageal count <15 eosinophils per high-power field [eos/hpf]). Key secondary endpoints were the proportions with complete histological remission (peak count ≤1 eos/hpf) and partial remission (peak counts ≤10 and ≤6 eos/hpf) and changes from baseline in peak eosinophil count and scores on the Eosinophilic Esophagitis Histology Scoring System (EoEHSS), Eosinophilic Esophagitis Endoscopic Reference Score (EREFS), Eosinophilic Esophagitis Activity Index (EEsAI), and quality of life (Adult Eosinophilic Esophagitis Quality-of-Life and Patient Reported Outcome Measurement Information System Global Health questionnaires). Individuals without histological response to 1FED could proceed to 6FED, and those without histological response to 6FED could proceed to swallowed topical fluticasone propionate 880 μg twice per day (with unrestricted diet), for 6 weeks. Histological remission after switching therapy was assessed as a secondary endpoint. Efficacy and safety analyses were done in the intention-to-treat (ITT) population. This trial is registered on ClinicalTrials.gov, NCT02778867, and is completed.

FINDINGS

Between May 23, 2016, and March 6, 2019, 129 patients (70 [54%] men and 59 [46%] women; mean age 37·0 years [SD 10·3]) were enrolled, randomly assigned to 1FED (n=67) or 6FED (n=62), and included in the ITT population. At 6 weeks, 25 (40%) of 62 patients in the 6FED group had histological remission compared with 23 (34%) of 67 in the 1FED group (difference 6% [95% CI -11 to 23]; p=0·58). We found no significant difference between the groups at stricter thresholds for partial remission (≤10 eos/hpf, difference 7% [-9 to 24], p=0·46; ≤6 eos/hpf, 14% [-0 to 29], p=0·069); the proportion with complete remission was significantly higher in the 6FED group than in the 1FED group (difference 13% [2 to 25]; p=0·031). Peak eosinophil counts decreased in both groups (geometric mean ratio 0·72 [0·43 to 1·20]; p=0·21). For 6FED versus 1FED, mean changes from baseline in EoEHSS (-0·23 vs -0·15; difference -0·08 [-0·21 to 0·05]; p=0·23), EREFS (-1·0 vs -0·6; difference -0·4 [-1·1 to 0·3]; p=0·28), and EEsAI (-8·2 vs -3·0; difference -5·2 [-11·2 to 0·8]; p=0·091) were not significantly different. Changes in quality-of-life scores were small and similar between the groups. No adverse event was observed in more than 5% of patients in either diet group. For patients without histological response to 1FED who proceeded to 6FED, nine (43%) of 21 reached histological remission; for patients without histological response to 6FED who proceeded to fluticasone propionate, nine (82%) of 11 reached histological remission.

INTERPRETATION

Histological remission rates and improvements in histological and endoscopic features were similar after 1FED and 6FED in adults with eosinophilic oesophagitis. 6FED had efficacy in just less than half of 1FED non-responders and steroids had efficacy in most 6FED non-responders. Our findings indicate that eliminating animal milk alone is an acceptable initial dietary therapy for eosinophilic oesophagitis.

FUNDING

US National Institutes of Health.

Vitamin D receptor and STAT6 interactome governs oesophageal epithelial barrier responses to IL-13 signalling

OBJECTIVE

The contribution of vitamin D (VD) deficiency to the pathogenesis of allergic diseases remains elusive. We aimed to define the impact of VD on oesophageal allergic inflammation.

DESIGN

We assessed the genomic distribution and function of VD receptor (VDR) and STAT6 using histology, molecular imaging, motif discovery and metagenomic analysis. We examined the role of VD supplementation in oesophageal epithelial cells, in a preclinical model of IL-13-induced oesophageal allergic inflammation and in human subjects with eosinophilic oesophagitis (EoE).

RESULTS

VDR response elements were enriched in oesophageal epithelium, suggesting enhanced VDR binding to functional gene enhancer and promoter regions. Metagenomic analysis showed that VD supplementation reversed dysregulation of up to 70% of the transcriptome and epigenetic modifications (H3K27Ac) induced by IL-13 in VD-deficient cells, including genes encoding the transcription factors HIF1A and SMAD3, endopeptidases (SERPINB3) and epithelial-mesenchymal transition mediators (TGFBR1, TIAM1, SRC, ROBO1, CDH1). Molecular imaging and chromatin immunoprecipitation showed VDR and STAT6 colocalisation within the regulatory regions of the affected genes, suggesting that VDR and STAT6 interactome governs epithelial tissue responses to IL-13 signalling. Indeed, VD supplementation reversed IL-13-induced epithelial hyperproliferation, reduced dilated intercellular spaces and barrier permeability, and improved differentiation marker expression (filaggrin, involucrin). In a preclinical model of IL-13-mediated oesophageal allergic inflammation and in human EoE, VD levels inversely associated with severity of oesophageal eosinophilia and epithelial histopathology.

CONCLUSIONS

Collectively, these findings identify VD as a natural IL-13 antagonist with capacity to regulate the oesophageal epithelial barrier functions, providing a novel therapeutic entry point for type 2 immunity-related diseases.

Genome-wide admixture and association analysis identifies African ancestry-specific risk loci of eosinophilic esophagitis in African Americans

BACKGROUND

Eosinophilic esophagitis (EoE), a chronic allergic inflammatory disease, is linked to multiple genetic risk factors, but studies have focused on populations of European ancestry. Few studies have assessed Black or African American (AA) populations for loci involved in EoE susceptibility.

OBJECTIVE

We performed admixture mapping (AM) and genome-wide association study (GWAS) of EoE using participants from AA populations.

METHODS

We conducted AM and GWAS of EoE using 137 EoE cases and 1465 healthy controls from the AA population. Samples were genotyped using molecular evolutionary genetics analysis (MEGA). Genotype imputation was carried out with the Consortium on Asthma Among African-Ancestry Populations in the Americas (CAAPA) reference panel using the Michigan Imputation Server. Global and local ancestry inference was carried out, followed by fine mapping and RNA sequencing. After quality control filtering, over 6,000,000 variants were tested by logistic regression adjusted for sex, age, and global ancestry.

RESULTS

The global African ancestry proportion was found to be significantly lower among cases than controls (0.751 vs 0.786, P = .012). Case-only AM identified 3 significant loci (9p13.3, 12q24.22-23, and 15q11.2) associated with EoE, of which 12q24.22-23 and 9p13.3 were further replicated in the case-control analysis, with associations observed with African ancestry. Fine mapping and multiomic functional annotations prioritized the variants rs11068264 (FBXW8) and rs7307331 (VSIG10) at 12q24.23 and rs2297879 (ARHGEF39) at 9p13.3. GWAS identified 1 genome-wide significant locus at chromosome 1p22.3 (rs17131726, DDAH1) and 10 other suggestive loci. Most GWAS variants were low-frequency African ancestry-specific variants. RNA sequencing revealed that esophageal DDAH1 and VSIG10 were downregulated and ARHGEF39 upregulated among EoE cases.

CONCLUSIONS

GWAS and AM for EoE in AA revealed that African ancestry-specific genetic susceptibility loci exist at 1p22.3, 9p13.3, and 12q24.23, providing evidence of ancestry-specific inheritance of EoE. More independent genetic studies of different ancestries for EoE are needed.

Single cell transcriptomic analysis of HPV16-infected epithelium identifies a keratinocyte subpopulation implicated in cancer

Persistent HPV16 infection is a major cause of the global cancer burden. The viral life cycle is dependent on the differentiation program of stratified squamous epithelium, but the landscape of keratinocyte subpopulations which support distinct phases of the viral life cycle has yet to be elucidated. Here, single cell RNA sequencing of HPV16 infected compared to uninfected organoids identifies twelve distinct keratinocyte populations, with a subset mapped to reconstruct their respective 3D geography in stratified squamous epithelium. Instead of conventional terminally differentiated cells, an HPV-reprogrammed keratinocyte subpopulation (HIDDEN cells) forms the surface compartment and requires overexpression of the ELF3/ESE-1 transcription factor. HIDDEN cells are detected throughout stages of human carcinogenesis including primary human cervical intraepithelial neoplasias and HPV positive head and neck cancers, and a possible role in promoting viral carcinogenesis is supported by TCGA analyses. Single cell transcriptome information on HPV-infected versus uninfected epithelium will enable broader studies of the role of individual keratinocyte subpopulations in tumor virus infection and cancer evolution.

Molecular analysis of duodenal eosinophilia

BACKGROUND

Eosinophilic duodenitis (EoD), characterized by nonspecific gastrointestinal symptoms and increased numbers of duodenal eosinophils, may be in the eosinophilic gastrointestinal disease spectrum. However, diagnostic thresholds and pathogenic processes of duodenal tissue eosinophilia are inadequately characterized.

OBJECTIVE

We aimed to define an EoD transcriptome and pathologic pathways.

METHODS

RNA sequencing and histologic features of human duodenal biopsy samples were analyzed as a function of duodenal eosinophils levels. For analyses, we defined EoD as more than 52 peak eosinophils/hpf (n = 8), duodenal eosinophilia as 30 to 52 eosinophils/hpf (n = 11), and normal controls as fewer than 30 eosinophils/hpf (n = 8). Associations between gene expression and histologic features were analyzed with Spearman correlation.

RESULTS

We identified 382 differentially expressed genes (EoD transcriptome) between EoD and normal controls (>2-fold change [adjusted P < .05]). The EoD transcriptome distinguished EoD from controls (duodenal eosinophilia and normal controls). The duodenal eosinophil count was correlated with a distinct EoD transcriptome when 50 to 60 peak eosinophils/hpf were present. The EoD transcriptome was enriched in genes involved in IL-4/IL-13 signaling, mast cells, and myeloid progenitor cells. Among duodenal histologic features, lamina propria eosinophil sheets was the most associated with transcriptomic changes (r = 0.66; P < .01). EoD gene signatures were shared with eosinophilic esophagitis and eosinophilic gastritis but not with eosinophilic colitis or celiac disease.

CONCLUSION

We have identified an EoD transcriptomic signature that emerges at 50 to 60 peak eosinophils/hpf and established EoD as part of a spectrum of upper eosinophilic gastrointestinal disorder associated with type 2 immunity and distinct from eosinophilic colitis and celiac disease. These findings provide a basis for improving diagnosis and treatment.

Mucosal Microbiota Associated With Eosinophilic Esophagitis and Eosinophilic Gastritis

OBJECTIVE

The aim of the study was to determine the mucosal microbiota associated with eosinophilic esophagitis (EoE) and eosinophilic gastritis (EoG) in a geographically diverse cohort of patients compared to controls.

METHODS

We conducted a prospective study of individuals with eosinophilic gastrointestinal disease (EGID) in the Consortium of Eosinophilic Gastrointestinal Disease Researchers, including pediatric and adult tertiary care centers. Eligible individuals had clinical data, mucosal biopsies, and stool collected. Total bacterial load was determined from mucosal biopsy samples by quantitative polymerase chain reaction (PCR). Community composition was determined by small subunit rRNA gene amplicons.

RESULTS

One hundred thirty-nine mucosal biopsies were evaluated corresponding to 93 EoE, 17 EoG, and 29 control specimens (18 esophageal) from 10 sites across the United States. Dominant community members across disease activity differed significantly. When comparing EoE and EoG with controls, the dominant taxa in individuals with EGIDs was increased ( Streptococcus in esophagus; Prevotella in stomach). Specific taxa were associated with active disease for both EoE ( Streptococcus , Gemella ) and EoG ( Leptotrichia ), although highly individualized communities likely impacted statistical testing. Alpha diversity metrics were similar across groups, but with high variability among individuals. Stool analyses did not correlate with bacterial communities found in mucosal biopsy samples and was similar in patients and controls.

CONCLUSIONS

Dominant community members ( Streptococcus for EoE, Prevotella for EoG) were different in the mucosal biopsies but not stool of individuals with EGIDs compared to controls; taxa associated with EGIDs were highly variable across individuals. Further study is needed to determine if therapeutic interventions contribute to the observed community differences.

The role of biologics in pediatric food allergy and eosinophilic gastrointestinal disorders

Continuing insight into the molecular mechanisms of atopic disorders has enabled the development of biologics to precisely target these diseases. Food allergy (FA) and eosinophilic gastrointestinal disorders (EGIDs) are driven by similar inflammatory molecular mechanisms and exist along the same atopic disease spectrum. Therefore, many of the same biologics are being investigated to target key drivers of mechanisms shared across the disease states. The enormous potential of biologics for the treatment of FA and EGIDs is highlighted by the significant increases in the number of ongoing clinical trials (more than 30) evaluating their use in these disease states, as well as by the recent US Food and Drug Administration approval of dupilumab for the treatment of eosinophilic esophagitis. Here we discuss past and current research into the use of biologics in FA and EGIDs and their potential role in improving treatment options in the future, with the need to have biologics widely clinically available.

Hypereosinophilic syndrome in Europe: Retrospective study of treatment patterns, clinical manifestations, and healthcare resource utilization

BACKGROUND

The burden of hypereosinophilic syndrome (HES) in Europe is not well characterized.

OBJECTIVE

To evaluate real-world patient characteristics, treatment patterns, clinical manifestations, and healthcare resource utilization for patients with HES from France, Germany, Italy, Spain, and the United Kingdom.

METHODS

In this retrospective, noninterventional study, data for patients with a physician-confirmed diagnosis of HES were abstracted from medical chart reviews. Patients were aged 6 years or older at the time of HES diagnosis and had 1 or more years of follow-up from the index date (first clinic visit between January 2015 and December 2019). Data on treatment patterns, comorbidities, clinical manifestations, clinical outcomes, and healthcare resource utilization were collected from diagnosis or index date to end of follow-up.

RESULTS

Data for 280 patients were abstracted from medical charts by 121 physicians treating HES, with multiple specialties. Most patients (55%) had idiopathic HES, and 24% had myeloid HES; the median number (interquartile range [IQR]) of diagnostic tests per patient was 10 (6-12). The most common comorbidities were asthma (45%) and anxiety or depression (36%). Most patients (89%) used oral corticosteroids; 64% used immunosuppressants or cytotoxic agents, and 44% used biologics. Patients had a median (IQR) of 3 clinical manifestations (1-5), most commonly constitutional (63%), lung (49%), and skin (48%). Twenty-three percent of patients experienced a flare, and 40% had a complete treatment response. Some patients (30%) were hospitalized with a median (IQR) stay of 9 days (5-15) for HES-related issues.

CONCLUSION

Patients with HES across 5 European countries had a substantial disease burden despite extensive oral corticosteroids treatment, highlighting the need for additional targeted therapies.

Food allergy characteristics associated with co-existing eosinophilic esophagitis in FARE Registry participants

BACKGROUND

Eosinophilic esophagitis (EoE) can co-exist in individuals with food allergy.

OBJECTIVE

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

METHODS

Data were derived from two Food Allergy Research and Education (FARE) 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=6,074; ages <1 year->80 years, mean[SD] 20.20[15.37]), reported having EoE. The odds of having EoE were significantly greater in male participants (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 healthcare utilization for food-related allergic reactions (aOR=1.3, 95%CI: 1.01-1.67) - specifically ICU 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.

CONCLUSION

These self-reported data showed that co-existing 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 healthcare needs of food allergic patients with EoE.

Protease allergens as initiators-regulators of allergic inflammation

Tremendous progress in the last few years has been made to explain how seemingly harmless environmental proteins from different origins can induce potent Th2-biased inflammatory responses. Convergent findings have shown the key roles of allergens displaying proteolytic activity in the initiation and progression of the allergic response. Through their propensity to activate IgE-independent inflammatory pathways, certain allergenic proteases are now considered as initiators for sensitization to themselves and to non-protease allergens. The protease allergens degrade junctional proteins of keratinocytes or airway epithelium to facilitate allergen delivery across the epithelial barrier and their subsequent uptake by antigen-presenting cells. Epithelial injuries mediated by these proteases together with their sensing by protease-activated receptors (PARs) elicit potent inflammatory responses resulting in the release of pro-Th2 cytokines (IL-6, IL-25, IL-1β, TSLP) and danger-associated molecular patterns (DAMPs; IL-33, ATP, uric acid). Recently, protease allergens were shown to cleave the protease sensor domain of IL-33 to produce a super-active form of the alarmin. At the same time, proteolytic cleavage of fibrinogen can trigger TLR4 signaling, and cleavage of various cell surface receptors further shape the Th2 polarization. Remarkably, the sensing of protease allergens by nociceptive neurons can represent a primary step in the development of the allergic response. The goal of this review is to highlight the multiple innate immune mechanisms triggered by protease allergens that converge to initiate the allergic response.

Epithelial cell-expressed type II IL-4 receptor mediates eosinophilic esophagitis

BACKGROUND

Eosinophilic esophagitis (EoE) is a chronic, food-driven allergic disease, characterized by eosinophil-rich inflammation in the esophagus. The histopathological and clinical features of EoE have been attributed to overproduction of the type 2 cytokines IL-4 and IL-13, which mediate profound alterations in the esophageal epithelium and neutralizing of their shared receptor component (IL-4Rα) with a human antibody drug (dupilumab) demonstrates clinical efficacy. Yet, the relative contribution of IL-4 and IL-13 and whether the type II IL-4 receptor (comprised of the IL-4Rα chain in association with IL-13Rα1) mediates this effect has not been determined.

METHODS

Experimental EoE was induced in WT, Il13ra1^-/- , and Krt14^Cre /Il13ra1^fl/fl mice by skin-sensitized using 4-ethoxymethylene-2-phenyl-2-oxazolin (OXA) followed by intraesophageal challenges. Esophageal histopathology was determined histologically. RNA was extracted and sequenced for transcriptome analysis and compared with human EoE RNAseq data.

RESULTS

Induction of experimental EoE in mice lacking Il13ra1 and in vivo IL-13 antibody-based neutralization experiments blocked antigen-induced esophageal epithelial and lamina propria thickening, basal cell proliferation, eosinophilia, and tissue remodeling. In vivo targeted deletion of Il13ra1 in esophageal epithelial cells rendered mice protected from experimental EoE. Single-cell RNA sequencing analysis of human EoE biopsies revealed predominant expression of IL-13Rα1 in epithelial cells and that EoE signature genes correlated with IL-13 expression compared with IL-4.

CONCLUSIONS

We demonstrate a definitive role for IL-13 signaling via IL-13Rα1 in EoE. These data provide mechanistic insights into the mode of action of current therapies in EoE and highlight the type II IL-4R as a future therapeutic target.

Dupilumab in Adults and Adolescents with Eosinophilic Esophagitis

BACKGROUND

Dupilumab, a fully human monoclonal antibody, blocks interleukin-4 and interleukin-13 signaling, which have key roles in eosinophilic esophagitis.

METHODS

We conducted a three-part, phase 3 trial in which patients 12 years of age or older underwent randomization in a 1:1 ratio to receive subcutaneous dupilumab at a weekly dose of 300 mg or placebo (Part A) or in a 1:1:1 ratio to receive 300 mg of dupilumab either weekly or every 2 weeks or weekly placebo (Part B) up to week 24. Eligible patients who completed Part A or Part B continued the trial in Part C, in which those who completed Part A received dupilumab at a weekly dose of 300 mg up to week 52 (the Part A-C group); Part C that included the eligible patients from Part B is ongoing. The two primary end points at week 24 were histologic remission (≤6 eosinophils per high-power field) and the change from baseline in the Dysphagia Symptom Questionnaire (DSQ) score (range, 0 to 84, with higher values indicating more frequent or more severe dysphagia).

RESULTS

In Part A, histologic remission occurred in 25 of 42 patients (60%) who received weekly dupilumab and in 2 of 39 patients (5%) who received placebo (difference, 55 percentage points; 95% confidence interval [CI], 40 to 71; P<0.001). In Part B, histologic remission occurred in 47 of 80 patients (59%) with weekly dupilumab, in 49 of 81 patients (60%) with dupilumab every 2 weeks, and in 5 of 79 patients (6%) with placebo (difference between weekly dupilumab and placebo, 54 percentage points; 95% CI, 41 to 66 [P<0.001]; difference between dupilumab every 2 weeks and placebo, 56 percentage points; 95% CI, 43 to 69 [not significant per hierarchical testing]). The mean (±SD) DSQ scores at baseline were 33.6±12.41 in Part A and 36.7±11.22 in Part B; the scores improved with weekly dupilumab as compared with placebo, with differences of -12.32 (95% CI, -19.11 to -5.54) in Part A and -9.92 (95% CI, -14.81 to -5.02) in Part B (both P<0.001) but not with dupilumab every 2 weeks (difference in Part B, -0.51; 95% CI, -5.42 to 4.41). Serious adverse events occurred in 9 patients during the Part A or B treatment period (in 7 who received weekly dupilumab, 1 who received dupilumab every 2 weeks, and 1 who received placebo) and in 1 patient in the Part A-C group during the Part C treatment period who received placebo in Part A and weekly dupilumab in Part C.

CONCLUSIONS

Among patients with eosinophilic esophagitis, subcutaneous dupilumab administered weekly improved histologic outcomes and alleviated symptoms of the disease. (Funded by Sanofi and Regeneron Pharmaceuticals; ClinicalTrials.gov number, NCT03633617.).

Scientific journey to the first FDA-approved drug for eosinophilic esophagitis

When eosinophilia was first associated with esophagitis, it was thought to reflect gastroesophageal reflux disease, especially given the efficacy of reflux medications to abate esophageal eosinophilia in many individuals. Subsequent studies demonstrated disease remittance with amino acid-based formulas and conversely induction of esophageal eosinophilia in mice following allergen challenge. These results, along with the finding that proton pump inhibitors alleviated esophageal eosinophilia by an anti-inflammatory mechanism, turned attention away from an acid-induced pathogenesis and established eosinophilic esophagitis (EoE) as a separate disease entity driven by allergic inflammation. The disease underpinnings were elucidated by analysis of esophageal transcriptomic profiling, revealing gene signatures orchestrated by type 2 cytokine signaling, mainly IL-13. Preclinical studies showed that IL-13 overproduction was sufficient to induce EoE-like changes in mice and human ex vivo systems and conversely that inhibiting IL-13 signaling attenuated these processes. An early proof-of-principle study with a humanized anti-IL-13 mAb in patients with EoE revealed correction of the EoE transcriptome and attenuation of esophageal eosinophilia, providing a rationale for advancing anti-type 2 cytokine therapy for EoE. Dupilumab, a precision therapeutic mAb that blocks the shared IL-13 and IL-4 receptor, is the first drug to advance through clinical trials and receive US Food and Drug Administration approval for EoE. The ability of dupilumab to improve clinical, histologic, endoscopic, and molecular features of EoE and garner US Food and Drug Administration approval is a victory for science, rare diseases, patients, and advocacy and provides a framework for developing additional EoE treatments and approved treatments for eosinophilic gastrointestinal disease beyond the esophagus.

International Consensus Recommendations for Eosinophilic Gastrointestinal Disease Nomenclature

BACKGROUND & AIMS

Substantial heterogeneity in terminology used for eosinophilic gastrointestinal diseases (EGIDs), particularly the catchall term "eosinophilic gastroenteritis," limits clinical and research advances. We aimed to achieve an international consensus for standardized EGID nomenclature.

METHODS

This consensus process utilized Delphi methodology. An initial naming framework was proposed and refined in iterative fashion, then assessed in a first round of Delphi voting. Results were discussed in 2 consensus meetings, and the framework was updated and reassessed in a second Delphi vote, with a 70% threshold set for agreement.

RESULTS

Of 91 experts participating, 85 (93%) completed the first and 82 (90%) completed the second Delphi surveys. Consensus was reached on all but 2 statements. "EGID" was the preferred umbrella term for disorders of gastrointestinal (GI) tract eosinophilic inflammation in the absence of secondary causes (100% agreement). Involved GI tract segments will be named specifically and use an "Eo" abbreviation convention: eosinophilic gastritis (now abbreviated EoG), eosinophilic enteritis (EoN), and eosinophilic colitis (EoC). The term "eosinophilic gastroenteritis" is no longer preferred as the overall name (96% agreement). When >2 GI tract areas are involved, the name should reflect all of the involved areas.

CONCLUSIONS

This international process resulted in consensus for updated EGID nomenclature for both clinical and research use. EGID will be the umbrella term, rather than "eosinophilic gastroenteritis," and specific naming conventions by location of GI tract involvement are recommended. As more data are developed, this framework can be updated to reflect best practices and the underlying science.

Management of eosinophilic esophagitis associated food impaction in Europe and the United States

Eosinophilic esophagitis (EoE) is the most common cause of esophageal food impaction (EFI). Approaches to management of EFI due to EoE have not been well characterized. We conducted a web-based survey to understand approaches to management of EFI due to EoE among endoscopists. Questions focused on management of patients from presentation to post-endoscopy follow-up. The survey was administered to a list of eligible candidates provided by societies of gastroenterology. A total of 308 endoscopists completed the questionnaire. The majority (83%) practiced in Europe and treated adults (78%). Most agreed patients should be advised to seek emergency care (66%) within 1 to 2 hours (41% agreement). There was agreement that medications to induce vomiting should be avoided (84%) and that blood tests or imaging studies were usually not required before endoscopy. By contrast, there was more variability in the type of sedation recommended and the need for endotracheal intubation, especially when comparing more experienced with less experienced EoE-endoscopists. Overall, fewer than half (43%) respondents recommended obtaining esophageal biopsies during the initial endoscopy. However, there were significant differences in the proportion who recommended biopsies based on level of EoE-experience (25, 52, 77%, P < 0.001; less vs. moderate vs. very experienced) and comparing pediatric and adult endoscopists (32, vs. 79%, P < 0.001; adult vs. pediatric). There exists heterogeneity among endoscopists in recommendations to manage EFI in patients with EoE. These findings support development of clinical guidelines and new studies to clarify the rationale for best practices. Key summary: Established knowledge-The optimal management of patients with esophageal food impaction due to eosinophilic esophagitis from presentation at the emergency department to postendoscopy care is unclear. New findings-Considerable recommendation variation exists in the management of EFI in patients with EoE. Our findings provide a rationale for the creation of consensus practice guidelines and further study into best practices.

Mepolizumab Reduces Hypereosinophilic Syndrome Flares Irrespective of Blood Eosinophil Count and Interleukin-5

BACKGROUND

Mepolizumab, an anti-interleukin-5 (IL-5) antibody, reduces disease flares in patients with hypereosinophilic syndrome (HES). Factors predicting treatment response are unknown.

OBJECTIVE

To assess mepolizumab efficacy by baseline blood eosinophil count (BEC) and serum IL-5 level in patients with HES.

METHODS

This post hoc analysis used data from the phase III study assessing mepolizumab in patients with HES (NCT02836496). Patients 12 years old or older, with HES for 6 or more months, 2 or more flares in the previous year, and BEC ≥1,000 cells/μL at screening were randomized (1:1) to 4-weekly subcutaneous mepolizumab (300 mg) or placebo, plus baseline HES therapy, for 32 weeks. The proportion of patients experiencing 1 or more flares (wk 32), annualized flare rate, and proportion of patients with change from baseline in Brief Fatigue Inventory (BFI) item 3 (wk 32), were analyzed by baseline BEC (<1500/≥1500 to <2500/≥2500 cells/μL). Flare outcomes were assessed by baseline serum IL-5 (<7.81/≥7.81 pg/mL).

RESULTS

Across baseline BEC subgroups, mepolizumab reduced the proportion of patients experiencing 1 or more flares by 63% to 90% and flare rate by 58% to 84% (treatment-by-eosinophil interaction P = .76 and P = .90, respectively); patients had improved BFI item 3 score with mepolizumab versus placebo (cells/μL: <1,500: 54% vs 37%; ≥1,500 to <2,500: 47% vs 31%; ≥2,500: 61% vs 0%; treatment-by-eosinophil interaction P = .42). Most patients had undetectable baseline serum IL-5 levels; among these, mepolizumab versus placebo reduced the proportion of patients with 1 or more flares (77%) and flare rate (67%).

CONCLUSIONS

Mepolizumab was efficacious in the patients with HES studied, irrespective of baseline BEC. Undetectable IL-5 levels should not preclude mepolizumab treatment.

Eosinophil-lymphocyte interactions in the tumor microenvironment and cancer immunotherapy

Eosinophils are important effector cells and therapeutic targets in allergic diseases. Emerging data indicate that eosinophils infiltrate a variety of solid tumor types and have pleiotropic activities by at least two non-mutually exclusive mechanisms: direct interactions with tumor cells, and intricate cross-talk with lymphocytes. In light of the immune checkpoint inhibition revolution in cancer therapy, we review eosinophil-lymphocyte interactions in the tumor microenvironment. We also analyze potential interactions between eosinophils and lymphocyte subsets, including T cells, natural killer cells and innate lymphoid cells. We provide perspectives on the consequences of these interactions and how eosinophils are accessory cells that can affect the response to various forms of T cell-mediated immunotherapies and might be therapeutically targeted to improve cancer immunotherapy.

Risk factors for SARS-CoV-2 infection and transmission in households with children with asthma and allergy: A prospective surveillance study

BACKGROUND

Whether children and people with asthma and allergic diseases are at increased risk for severe acute respiratory syndrome virus 2 (SARS-CoV-2) infection is unknown.

OBJECTIVE

Our aims were to determine the incidence of SARS-CoV-2 infection in households with children and to also determine whether self-reported asthma and/or other allergic diseases are associated with infection and household transmission.

METHODS

For 6 months, biweekly nasal swabs and weekly surveys were conducted within 1394 households (N = 4142 participants) to identify incident SARS-CoV-2 infections from May 2020 to February 2021, which was the pandemic period largely before a vaccine and before the emergence of SARS-CoV-2 variants. Participant and household infection and household transmission probabilities were calculated by using time-to-event analyses, and factors associated with infection and transmission risk were determined by using regression analyses.

RESULTS

In all, 147 households (261 participants) tested positive for SARS-CoV-2. The household SARS-CoV-2 infection probability was 25.8%; the participant infection probability was similar for children (14.0% [95% CI = 8.0%-19.6%]), teenagers (12.1% [95% CI = 8.2%-15.9%]), and adults (14.0% [95% CI = 9.5%-18.4%]). Infections were symptomatic in 24.5% of children, 41.2% of teenagers, and 62.5% of adults. Self-reported doctor-diagnosed asthma was not a risk factor for infection (adjusted hazard ratio [aHR] = 1.04 [95% CI = 0.73-1.46]), nor was upper respiratory allergy or eczema. Self-reported doctor-diagnosed food allergy was associated with lower infection risk (aHR = 0.50 [95% CI = 0.32-0.81]); higher body mass index was associated with increased infection risk (aHR per 10-point increase = 1.09 [95% CI = 1.03-1.15]). The household secondary attack rate was 57.7%. Asthma was not associated with household transmission, but transmission was lower in households with food allergy (adjusted odds ratio = 0.43 [95% CI = 0.19-0.96]; P = .04).

CONCLUSION

Asthma does not increase the risk of SARS-CoV-2 infection. Food allergy is associated with lower infection risk, whereas body mass index is associated with increased infection risk. Understanding how these factors modify infection risk may offer new avenues for preventing infection.

Human Epidemiology and RespOnse to SARS-CoV-2 (HEROS): Objectives, Design and Enrollment Results of a 12-City Remote Observational Surveillance Study of Households with Children using Direct-to-Participant Methods

The Human Epidemiology and Response to SARS-CoV-2 (HEROS) is a prospective multi-city 6-month incidence study which was conducted from May 2020-February 2021. The objectives were to identify risk factors for SARS-CoV-2 infection and household transmission among children and people with asthma and allergic diseases, and to use the host nasal transcriptome sampled longitudinally to understand infection risk and sequelae at the molecular level. To overcome challenges of clinical study implementation due to the coronavirus pandemic, this surveillance study used direct-to-participant methods to remotely enroll and prospectively follow eligible children who are participants in other NIH-funded pediatric research studies and their household members. Households participated in weekly surveys and biweekly nasal sampling regardless of symptoms. The aim of this report is to widely share the methods and study instruments and to describe the rationale, design, execution, logistics and characteristics of a large, observational, household-based, remote cohort study of SARS-CoV-2 infection and transmission in households with children. The study enrolled a total of 5,598 individuals, including 1,913 principal participants (children), 1,913 primary caregivers, 729 secondary caregivers and 1,043 other household children. This study was successfully implemented without necessitating any in-person research visits and provides an approach for rapid execution of clinical research.