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.

A Clinical Severity Index for Eosinophilic Esophagitis: Development, Consensus, and Future Directions

BACKGROUND & AIMS

Disease activity and severity of eosinophilic esophagitis (EoE) dictate therapeutic options and management, but the decision-making process for determining severity varies among practitioners. To reduce variability in practice patterns and help clinicians monitor the clinical course of the disease in an office setting, we aimed to create an international consensus severity scoring index for EoE.

METHODS

A multidisciplinary international group of adult and pediatric EoE researchers and clinicians, as well as non-EoE allergy immunology and gastroenterology experts, formed 3 teams to review the existing literature on histology, endoscopy, and symptoms of EoE in the context of progression and severity. A steering committee convened a 1-day virtual meeting to reach consensus on each team's opinion on salient features of severity across key clinicopathologic domains and distill features that would allow providers to categorize disease severity.

RESULTS

Symptom features and complications and inflammatory and fibrostenotic features on both endoscopic and histologic examination were collated into a simplified scoring system-the Index of Severity for Eosinophilic Esophagitis (I-SEE)-that can be completed at routine clinic visits to assess disease severity using a point scale of 0-6 for mild, 7-14 for moderate, and ≥15 for severe EoE.

CONCLUSIONS

A multidisciplinary team of experts iteratively created a clinically usable EoE severity scoring system denominated "I-SEE" to guide practitioners in EoE management by standardizing disease components reflecting disease severity beyond eosinophil counts. I-SEE should be validated and refined using data from future clinical trials and routine clinical practice to increase its utilization and functionality.

A Clinical Severity Index for Eosinophilic Esophagitis: Development, Consensus, and Future Directions

BACKGROUND & AIMS

Disease activity and severity of eosinophilic esophagitis (EoE) dictate therapeutic options and management, but the decision-making process for determining severity varies among practitioners. To reduce variability in practice patterns and help clinicians monitor the clinical course of the disease in an office setting, we aimed to create an international consensus severity scoring index for EoE.

METHODS

A multidisciplinary international group of adult and pediatric EoE researchers and clinicians, as well as non-EoE allergy immunology and gastroenterology experts, formed 3 teams to review the existing literature on histology, endoscopy, and symptoms of EoE in the context of progression and severity. A steering committee convened a 1-day virtual meeting to reach consensus on each team's opinion on salient features of severity across key clinicopathologic domains and distill features that would allow providers to categorize disease severity.

RESULTS

Symptom features and complications and inflammatory and fibrostenotic features on both endoscopic and histologic examination were collated into a simplified scoring system-the Index of Severity for Eosinophilic Esophagitis (I-SEE)-that can be completed at routine clinic visits to assess disease severity using a point scale of 0-6 for mild, 7-14 for moderate, and ≥15 for severe EoE.

CONCLUSIONS

A multidisciplinary team of experts iteratively created a clinically usable EoE severity scoring system denominated "I-SEE" to guide practitioners in EoE management by standardizing disease components reflecting disease severity beyond eosinophil counts. I-SEE should be validated and refined using data from future clinical trials and routine clinical practice to increase its utilization and functionality.

A Deep Multi-Label Segmentation Network For Eosinophilic Esophagitis Whole Slide Biopsy Diagnostics

Eosinophilic esophagitis (EoE) is an allergic inflammatory condition of the esophagus associated with elevated numbers of eosinophils. Disease diagnosis and monitoring require determining the concentration of eosinophils in esophageal biopsies, a time-consuming, tedious and somewhat subjective task currently performed by pathologists. Here, we developed a machine learning pipeline to identify, quantitate and diagnose EoE patients' at the whole slide image level. We propose a platform that combines multi-label segmentation deep network decision support system with dynamics convolution that is able to process whole biopsy slide. Our network is able to segment both intact and not-intact eosinophils with a mean intersection over union (mIoU) of 0.93. This segmentation enables the local quantification of intact eosinophils with a mean absolute error of 0.611 eosinophils. We examined a cohort of 1066 whole slide images from 400 patients derived from multiple institutions. Using this set, our model achieved a global accuracy of 94.75%, sensitivity of 94.13%, and specificity of 95.25% in reporting EoE disease activity. Our work provides state-of-the-art performances on the largest EoE cohort to date, and successfully addresses two of the main challenges in EoE diagnostics and digital pathology, the need to detect several types of small features simultaneously, and the ability to analyze whole slides efficiently. Our results pave the way for an automated diagnosis of EoE and can be utilized for other conditions with similar challenges.

An International, Retrospective Study of Off-Label Biologic Use in the Treatment of Hypereosinophilic Syndromes

BACKGROUND

Treatment of hypereosinophilic syndrome (HES) often requires the use of immunomodulators with substantial side effect profiles. The emergence of biologics offers an alternative treatment modality.

OBJECTIVE

To examine real-world practice data to describe the safety and consequences of various biologics suspected to directly or indirectly affect eosinophilic inflammation for the treatment of HES.

METHODS

Retrospective data from 13 centers were collected via an online Research Electronic Data Capture repository. Inclusion criteria included (1) peripheral eosinophil count of 1,500/mm³ or greater without a secondary cause; (2) clinical manifestations attributable to the eosinophilia; and (3) having received mepolizumab (anti-IL-5), benralizumab (afucosylated anti-IL-5 receptor α), omalizumab (anti-IgE), alemtuzumab (anti-CD52), dupilumab (anti-IL-4 receptor α), or reslizumab (anti-IL-5) outside a placebo-controlled clinical trial.

RESULTS

Of the 151 courses of biologics prescribed for 121 patients with HES, 59% resulted in improved HES symptoms and 77% enabled tapering of other HES medications. Overall, 105 patients were receiving daily systemic glucocorticoids at the time of a biologic initiation and were able to reduce the glucocorticoid dose by a median reduction of 10 mg of daily prednisone equivalents. Biologics were generally safe and well-tolerated other than infusion reactions with alemtuzumab. Thirteen of 24 patients had clinical improvement after switching biologics and nine patients responded to increasing the dose of mepolizumab after a lack of response to a lower dose.

CONCLUSIONS

Biologics may offer a safer treatment alternative to existing therapies for HES, although the optimal dosing and choice for each subtype of HES remain to be determined. Limitations of this study include its retrospective nature and intersite differences in data collection and availability of each biologic.

Evaluating Eosinophilic Colitis as a Unique Disease Using Colonic Molecular Profiles: A Multi-Site Study

BACKGROUND & AIMS

Colonic eosinophilia, an enigmatic finding often referred to as eosinophilic colitis (EoC), is a poorly understood condition. Whether EoC is a distinct disease or a colonic manifestation of eosinophilic gastrointestinal diseases (EGIDs) or inflammatory bowel disease (IBD) is undetermined.

METHODS

Subjects with EoC (n = 27) and controls (normal [NL, n = 20], Crohn's disease [CD, n = 14]) were enrolled across sites associated with the Consortium of Eosinophilic Gastrointestinal Disease Researchers. EoC was diagnosed as colonic eosinophilia (ascending ≥100, descending ≥85, sigmoid ≥65 eosinophils/high-power field) with related symptoms. Colon biopsies were subjected to RNA sequencing. Associations between gene expression and histologic features were analyzed with Spearman correlation; operational pathways and cellular constituents were computationally derived.

RESULTS

We identified 987 differentially expressed genes (EoC transcriptome) between EoC and NL (>1.5-fold change, P < .05). Colonic eosinophil count correlated with 31% of EoC transcriptome, most notably with CCL11 and CLC (r = 0.78 and 0.77, P < .0001). Among EoC and other EGIDs, there was minimal transcriptomic overlap and minimal evidence of a strong allergic type 2 immune response in EoC compared with other EGIDs. Decreased cell cycle and increased apoptosis in EoC compared with NL were identified by functional enrichment analysis and immunostaining using Ki-67 and cleaved caspase-3. Pericryptal circumferential eosinophil collars were associated with the EoC transcriptome (P < .001). EoC transcriptome-based scores were reversible with disease remission and differentiated EoC from IBD, even after controlling for colonic eosinophil levels (P < .0001).

CONCLUSIONS

We established EoC transcriptomic profiles, identified mechanistic pathways, and integrated findings with parallel IBD and EGID data. These findings establish EoC as a distinct disease compared with other EGIDs and IBD, thereby providing a basis for improving diagnosis and treatment.

Epigenetic and transcriptional dysregulation in CD4+ T cells in patients with atopic dermatitis

Atopic dermatitis (AD) is one of the most common skin disorders among children. Disease etiology involves genetic and environmental factors, with 29 independent AD risk loci enriched for risk allele-dependent gene expression in the skin and CD4+ T cell compartments. We investigated the potential epigenetic mechanisms responsible for the genetic susceptibility of CD4+ T cells. To understand the differences in gene regulatory activity in peripheral blood T cells in AD, we measured chromatin accessibility (an assay based on transposase-accessible chromatin sequencing, ATAC-seq), nuclear factor kappa B subunit 1 (NFKB1) binding (chromatin immunoprecipitation with sequencing, ChIP-seq), and gene expression levels (RNA-seq) in stimulated CD4+ T cells from subjects with active moderate-to-severe AD, as well as in age-matched non-allergic controls. Open chromatin regions in stimulated CD4+ T cells were highly enriched for AD genetic risk variants, with almost half of the AD risk loci overlapping AD-dependent ATAC-seq peaks. AD-specific open chromatin regions were strongly enriched for NF-κB DNA-binding motifs. ChIP-seq identified hundreds of NFKB1-occupied genomic loci that were AD- or control-specific. As expected, the AD-specific ChIP-seq peaks were strongly enriched for NF-κB DNA-binding motifs. Surprisingly, control-specific NFKB1 ChIP-seq peaks were not enriched for NFKB1 motifs, but instead contained motifs for other classes of human transcription factors, suggesting a mechanism involving altered indirect NFKB1 binding. Using DNA sequencing data, we identified 63 instances of altered genotype-dependent chromatin accessibility at 36 AD risk variant loci (30% of AD risk loci) that might lead to genotype-dependent gene expression. Based on these findings, we propose that CD4+ T cells respond to stimulation in an AD-specific manner, resulting in disease- and genotype-dependent chromatin accessibility alterations involving NFKB1 binding.

Single-cell RNA sequencing of human esophageal epithelium in homeostasis and allergic inflammation

Inflammation of the esophageal epithelium is a hallmark of eosinophilic esophagitis (EoE), an emerging chronic allergic disease. Herein, we probed human esophageal epithelial cells at single-cell resolution during homeostasis and EoE. During allergic inflammation, the epithelial differentiation program was blocked, leading to loss of KRT6high differentiated populations and expansion of TOP2high proliferating and DSPhigh, SERPINB3high transitioning populations; however, there was stability of the stem cell-enriched PDPNhigh basal epithelial compartment. This differentiation program blockade was associated with dysregulation of transcription factors, including nuclear receptor signalers, in the most differentiated epithelial cells and altered NOTCH-related cell-to-cell communication. Each epithelial population expressed genes with allergic disease risk variants, supporting their functional interplay. The esophageal epithelium differed notably between EoE in histologic remission and controls, indicating that remission is a transitory state poised to relapse. Collectively, our data uncover the dynamic nature of the inflamed human esophageal epithelium and provide a framework to better understand esophageal health and disease.

Long-Lasting Dissociation of Esophageal Eosinophilia and Symptoms After Dilation in Adults With Eosinophilic Esophagitis

BACKGROUND & AIMS

Esophageal dilation improves dysphagia but not inflammation in eosinophilic esophagitis (EoE) patients. We investigated if dilation modifies the association between symptoms and peak esophageal eosinophils per high-power field (eos/hpf).

METHODS

Adults enrolled in a multisite prospective Consortium of Gastrointestinal Eosinophilic Disease Researchers Outcome Measures for Eosinophilic Gastrointestinal Diseases Across Ages observational study (NCT02523118) completed the symptom-based EoE activity index (EEsAI) patient-reported outcome instrument and underwent endoscopy with biopsy specimens. Patients were stratified based on dilation status as absent, performed 1 year or less before endoscopy, and performed more than 1 year before endoscopy. Assessments included Spearman correlations of the relationship between symptoms and eos/hpf and linear regression with EEsAI as the outcome, eos/hpf as predictor, and interaction for dilation and eos/hpf.

RESULTS

Among 100 patients (n = 61 males; median age, 37 y), 15 and 40 patients underwent dilation 1 year or less and more than 1 year before index endoscopy, respectively. In nondilated patients, the association between eos/hpf and symptoms was moderate (ρ = 0.49; P < .001); for a 10-eos/hpf increase, the predicted EEsAI increased by 2.69 (P = .002). In patients dilated 1 or less and more than 1 year before index endoscopy, this association was abolished (ρ = -0.38; P = .157 for ≤1 y and ρ = 0.02; P = .883 >1 y); for a 10-eos/hpf increase, the predicted EEsAI changed by -1.64 (P = .183) and 0.78 (P = .494), respectively. Dilation modified the association between symptoms and eos/hpf (P = .005 and P = .187 for interaction terms of eos/hpf and dilation 1 or less years before and more than 1 year before index endoscopy, respectively).

CONCLUSIONS

In nondilated EoE adults, eos/hpf correlate modestly with symptoms; this correlation was no longer appreciated in dilated patients, and the dilation effects lasted longer than 1 year. Dilation status should be considered in studies evaluating EoE treatment and for clinical follow-up evaluation.

Functional and Phenotypic Characterization of Siglec-6 on Human Mast Cells

Mast cells are tissue-resident cells that contribute to allergic diseases, among others, due to excessive or inappropriate cellular activation and degranulation. Therapeutic approaches to modulate mast cell activation are urgently needed. Siglec-6 is an immunoreceptor tyrosine-based inhibitory motif (ITIM)-bearing receptor selectively expressed by mast cells, making it a promising target for therapeutic intervention. However, the effects of its engagement on mast cells are poorly defined. Siglec-6 expression and endocytosis on primary human mast cells and mast cell lines were assessed by flow cytometry. SIGLEC6 mRNA expression was examined by single-cell RNAseq in esophageal tissue biopsy samples. The ability of Siglec-6 engagement or co-engagement to prevent primary mast cell activation was determined based on assessments of mediator and cytokine secretion and degranulation markers. Siglec-6 was highly expressed by all mast cells examined, and the SIGLEC6 transcript was restricted to mast cells in esophageal biopsy samples. Siglec-6 endocytosis occurred with delayed kinetics relative to the related receptor Siglec-8. Co-crosslinking of Siglec-6 with FcεRIα enhanced the inhibition of mast cell activation and diminished downstream ERK1/2 and p38 phosphorylation. The selective, stable expression and potent inhibitory capacity of Siglec-6 on human mast cells are favorable for its use as a therapeutic target in mast cell-driven diseases.

Acquired Esophageal Strictures in Children: Morphometric and Immunohistochemical Analyses

BACKGROUND

Esophageal strictures (ES) in children are not well characterized pathologically. We report unique histopathologic analyses of resected acquired ES and control esophagi (CE).

METHODS

Muscle layer thicknesses were measured in intact well-oriented areas; inflammatory cells were counted in the most inflamed high power field (hpf). Sections were stained with relevant antibodies. Results were expressed as median, lower and upper quartiles. Wilcoxon Rank Sums non-parametric test was used to compare groups; P ≤ 0.05 was considered significant.

RESULTS

All ES (N = 10) showed focal replacement of lamina propria, muscularis mucosa and submucosa by actin+ fibers emanating from muscularis propria. Compared to CE (N = 8), ES displayed significantly thickened muscularis mucosa and propria, and increased mast cells (tryptase- and chymase-positive), and eosinophils in muscle layers (all P ≤ 0.01). Matrix proteins periostin and fibronectin were identified in the muscle layers of CE, and in the extracellular matrix in areas of disrupted architecture in ES.

CONCLUSIONS

Compared to CE, acquired ES in children show significant structural alterations, including obliterative muscularization, inflammatory cell mural infiltrates, and extracellular matrix protein deposits. Therapies targeting connective tissue expansion, mast cells, eosinophils and inflammation may be beneficial to treat ES.

Impressions and aspirations from the FDA GREAT VI Workshop on Eosinophilic Gastrointestinal Disorders Beyond Eosinophilic Esophagitis and Perspectives for Progress in the Field

The US Food and Drug Administration hosted a workshop on July 21, 2021, to discuss the disease characteristics, natural history, and end points to assess treatment benefit in patients with eosinophilic gastrointestinal disorders (EGIDs) beyond eosinophilic esophagitis (EoE). Notably, EGIDs beyond EoE, such as eosinophilic gastritis, eosinophilic enteritis, and eosinophilic colitis, herein referred to as non-EoE EGIDs, are understudied relative to EoE. This workshop provided a forum for open discussion among stakeholders-medical professionals (including their societies and research groups), Food and Drug Administration representatives, an industry representative, and a patient representative-to facilitate drug development. Experts in many disciplines related to EGIDs, including allergy, immunology, epidemiology, gastroenterology, and pathology, and both adult and pediatric clinicians contributed. Herein, we discuss some of the insights of the material presented at the meeting and present perspectives on moving the field forward toward drug approval.

Determination of Biopsy Yield That Optimally Detects Eosinophilic Gastritis and/or Duodenitis in a Randomized Trial of Lirentelimab

BACKGROUND & AIMS

Eosinophilic gastritis (EG) and eosinophilic duodenitis (EoD), characterized by chronic gastrointestinal (GI) symptoms and increased numbers or activation of eosinophils and mast cells in the GI tract, are likely underdiagnosed. We aimed to determine rates of EG and EoD and number of biopsies required to optimize detection using screening data from a randomized trial of lirentelimab (AK002), an antibody against siglec-8 that depletes eosinophils and inhibits mast cells. We also characterized endoscopic features and symptoms of EG and EoD.

METHODS

Subjects with moderate-to-severe GI symptoms, assessed daily through a validated patient-reported outcome questionnaire, underwent endoscopy with a systematic gastric and duodenal biopsy protocol and histopathologic evaluation. EG diagnosis required presence of ≥30 eosinophils/high-power field (eos/hpf) in ≥5 hpfs and EoD required ≥30 eos/hpf in ≥3 hpfs. We analyzed diagnostic yields for EG and EoD and histologic, endoscopic, and clinical findings.

RESULTS

Of 88 subjects meeting symptom criteria, 72 were found to have EG and/or EoD (EG/EoD), including patients with no prior diagnosis of EG/EoD. We found that GI eosinophilia was patchy and that examination of multiple biopsies was required for diagnosis-an average of only 2.6 per 8 gastric biopsies and 2.2 per 4 duodenal biopsies per subject met thresholds for EG/EoD. Evaluation of multiple nonoverlapping hpfs in each of 8 gastric and 4 duodenal biopsies was required to capture 100% of EG/EoD cases. Neither endoscopic findings nor symptom severity correlated with eosinophil counts.

CONCLUSIONS

In an analysis of patients with moderate-to-severe GI symptoms participating in a clinical trial of lirentelimab for EG/EoD, we found eosinophilia to be patchy in gastric and duodenal biopsies. Counting eosinophils in at least 8 gastric and 4 duodenal biopsies is required to identify patients with EG/EoD, so they can receive appropriate treatment. (ClinicalTrials.gov, Number: NCT03496571).

The Climate Change Hypothesis for the Allergy Epidemic

The health consequences of climate change are being increasingly recognized. Herein, the climate change hypothesis is put forth as a substantial contributor to the growing global allergy epidemic. A call for deeper research and action on the impact of climate change on various aspects of allergic disease mechanisms, exacerbation, and prevalence is imperative.

Loss of Endothelial TSPAN12 Promotes Fibrostenotic Eosinophilic Esophagitis via Endothelial Cell-Fibroblast Crosstalk

BACKGROUND & AIMS

Eosinophilic esophagitis (EoE) can progress to fibrostenosis by unclear mechanisms. Herein, we investigated gene dysregulation in fibrostenotic EoE, its association with clinical parameters and specific pathways, and the functional consequences.

METHODS

Esophageal biopsies from subjects with EoE were collected across 11 Consortium of Eosinophilic Gastrointestinal Disease Researchers sites (n = 311) and 2 independent replication cohorts (n = 83). Inclusion criteria for fibrostenotic EoE were endoscopic rings, stricture, and/or a history of dilation. Endoscopic, histologic, and molecular features were assessed by the EoE Endoscopic Reference Score, EoE Histology Scoring System, EoE Diagnostic Panel, and RNA sequencing. Esophageal endothelial TSPAN12 expression and functional effects on barrier integrity and gene expression were analyzed in vitro.

RESULTS

TSPAN12 was the gene most correlated with fibrostenosis (r = -0.40, P < .001). TSPAN12 was lower in fibrostenotic EoE and correlated with EoE Endoscopic Reference Score, EoE Diagnostic Panel, and EoE Histology Scoring System (r = 0.34-0.47, P < .001). Lower TSPAN12 associated with smaller esophageal diameter (r = 0.44, P = .03), increased lamina propria fibrosis (r = -0.41, P < .001), and genes enriched in cell cycle-related pathways. Interleukin (IL)-13 reduced TSPAN12 expression in endothelial cells. Conversely, anti-IL-13 therapy increased TSPAN12 expression. TSPAN12 gene silencing increased endothelial cell permeability and dysregulated genes associated with extracellular matrix pathways. Endothelial cell-fibroblast crosstalk induced extracellular matrix changes relevant to esophageal remodeling.

CONCLUSIONS

Patients with fibrostenotic EoE express decreased levels of endothelial TSPAN12. We propose that IL-13 decreases TSPAN12, likely contributing to the chronicity of EoE by promoting tissue remodeling through fibroblast-endothelial cell crosstalk.

Diagnostic merits of the Eosinophilic Esophagitis Diagnostic Panel from a single esophageal biopsy

BACKGROUND

Eosinophilic esophagitis (EoE) is a histologically "patchy" disease with uneven eosinophil distribution along the esophagus, posing a dilemma for histologically analyzing endoscopic biopsy samples, especially when biopsy samples are limited to only the distal esophagus.

OBJECTIVE

We investigated whether molecular mRNA profiling of a distal esophageal biopsy sample predicts eosinophilia in the proximal esophagus.

METHODS

Esophageal biopsy samples (n = 507) from subjects with EoE were collected from multiple institutions, spanning adults and pediatric patients. Subjects were grouped on the basis of distinct distal (D) and proximal (P) eosinophil counts (D⁺P⁺, D⁺P^-, D^-P⁺, and D^-P^-, with + and - defined as ≥15 or <15 eosinophils/hpf, respectively). Molecular profiles were assessed by using the EoE Diagnostic Panel (EDP), a set of 96 esophageal transcripts used to derive the EDP score.

RESULTS

The distal EDP score was correlated with proximal eosinophil levels (r = -0.73; P < .0001). EDP analysis of a histologically negative distal biopsy sample predicted the presence of proximal esophagitis with high sensitivity (85%). In a 2-year follow-up focusing on the cases with discordant histologic and EDP results, histologically negative patients (D^-P^-) had higher rates of EoE relapse when the EDP was positive than when the EDP was negative (odds ratio = 11; P = .003), indicating predictive medicine capacity.

CONCLUSION

EDP analysis of a single distal esophageal biopsy sample predicts remote inflammation in patients with spatially heterogeneous eosinophilia and disease relapse in patients with histologic remission, providing diagnostic merit and predictive medicine capacity for molecular diagnosis of EoE.

Development of a core outcome set for therapeutic studies in eosinophilic esophagitis (COREOS)

BACKGROUND

End points used to determine treatment efficacy in eosinophilic esophagitis (EoE) have evolved over time. With multiple novel therapies in development for EoE, harmonization of outcomes measures will facilitate evidence synthesis and appraisal when comparing different treatments.

OBJECTIVE

We sought to develop a core outcome set (COS) for controlled and observational studies of pharmacologic and diet interventions in adult and pediatric patients with EoE.

METHODS

Candidate outcomes were generated from systematic literature reviews and patient engagement interviews and surveys. Consensus was established using an iterative Delphi process, with items voted on using a 9-point Likert scale and with feedback from other participants to allow score refinement. Consensus meetings were held to ratify the outcome domains of importance and the core outcome measures. Stakeholders were recruited internationally and included adult and pediatric gastroenterologists, allergists, dieticians, pathologists, psychologists, researchers, and methodologists.

RESULTS

The COS consists of 4 outcome domains for controlled and observational studies: histopathology, endoscopy, patient-reported symptoms, and EoE-specific quality of life. A total of 69 stakeholders (response rate 95.8%) prioritized 42 outcomes in a 2-round Delphi process, and the final ratification meeting generated consensus on 33 outcome measures. These included measurement of the peak eosinophil count, Eosinophilic Esophagitis Histology Scoring System, Eosinophilic Esophagitis Endoscopic Reference Score, and patient-reported measures of dysphagia and quality of life.

CONCLUSIONS

This interdisciplinary collaboration involving global stakeholders has produced a COS that can be applied to adult and pediatric studies of pharmacologic and diet therapies for EoE and will facilitate meaningful treatment comparisons and improve the quality of data synthesis.

Host-Microbiota Interactions in the Esophagus During Homeostasis and Allergic Inflammation

BACKGROUND & AIMS

Microbiota composition and mechanisms of host-microbiota interactions in the esophagus are unclear. We aimed to uncover fundamental information about the esophageal microbiome and its potential significance to eosinophilic esophagitis (EoE).

METHODS

Microbiota composition, transplantation potential, and antibiotic responsiveness in the esophagus were established via 16S ribosomal RNA sequencing. Functional outcomes of microbiota colonization were assessed by RNA sequencing analysis of mouse esophageal epithelium and compared with the human EoE transcriptome. The impact of dysbiosis was assessed using a preclinical model of EoE.

RESULTS

We found that the murine esophagus is colonized with diverse microbial communities within the first month of life. The esophageal microbiota is distinct, dominated by Lactobacillales, and demonstrates spatial heterogeneity as the proximal and distal esophagus are enriched in Bifidobacteriales and Lactobacillales, respectively. Fecal matter transplantation restores the esophageal microbiota, demonstrating that the local environment drives diversity. Microbiota colonization modifies esophageal tissue morphology and gene expression that is enriched in pathways associated with epithelial barrier function and overlapping with genes involved in EoE, including POSTN, KLK5, and HIF1A. Finally, neonatal antibiotic treatment reduces the abundance of Lactobacillales and exaggerates type 2 inflammation in the esophagus. Clinical data substantiated loss of esophageal Lactobacillales in EoE compared with controls.

CONCLUSIONS

The esophagus has a unique microbiome with notable differences between its proximal and distal regions. Fecal matter transplantation restores the esophageal microbiome. Antibiotic-induced dysbiosis exacerbates disease in a murine model of EoE. Collectively, these data establish the composition, transplantation potential, antibiotic responsiveness, and host-microbiota interaction in the esophagus and have implications for gastrointestinal health and disease.

Harnessing artificial intelligence to infer novel spatial biomarkers for the diagnosis of eosinophilic esophagitis

Eosinophilic esophagitis (EoE) is a chronic allergic inflammatory condition of the esophagus associated with elevated esophageal eosinophils. Second only to gastroesophageal reflux disease, EoE is one of the leading causes of chronic refractory dysphagia in adults and children. EoE is a clinicopathologic disorder and the histological portion of the diagnosis requires enumerating the density of esophageal eosinophils in esophageal biopsies, and evaluating additional features such as basal zone hyperplasia is helpful. However, this task requires time-consuming, somewhat subjective manual analysis, thus reducing the ability to process the complex tissue structure and infer its relationship with the patient's clinical status. Previous artificial intelligence (AI) approaches that aimed to improve histology-based diagnosis focused on recapitulating identification and quantification of the area of maximal eosinophil density, the gold standard manual metric for determining EoE disease activity. However, this metric does not account for the distribution of eosinophils or other histological features, over the whole slide image. Here, we developed an artificial intelligence platform that infers local and spatial biomarkers based on semantic segmentation of intact eosinophils and basal zone distributions. Besides the maximal density of eosinophils [referred to as Peak Eosinophil Count (PEC)] and a maximal basal zone fraction, we identify the value of two additional metrics that reflect the distribution of eosinophils and basal zone fractions. This approach enables a decision support system that predicts EoE activity and potentially classifies the histological severity of EoE patients. We utilized a cohort that includes 1,066 biopsy slides from 400 subjects to validate the system's performance and achieved a histological severity classification accuracy of 86.70%, sensitivity of 84.50%, and specificity of 90.09%. Our approach highlights the importance of systematically analyzing the distribution of biopsy features over the entire slide and paves the way toward a personalized decision support system that will assist not only in counting cells but can also potentially improve diagnosis and provide treatment prediction.

Remote immune processes revealed by immune-derived circulating cell-free DNA

Blood cell counts often fail to report on immune processes occurring in remote tissues. Here, we use immune cell type-specific methylation patterns in circulating cell-free DNA (cfDNA) for studying human immune cell dynamics. We characterized cfDNA released from specific immune cell types in healthy individuals (N = 242), cross sectionally and longitudinally. Immune cfDNA levels had no individual steady state as opposed to blood cell counts, suggesting that cfDNA concentration reflects adjustment of cell survival to maintain homeostatic cell numbers. We also observed selective elevation of immune-derived cfDNA upon perturbations of immune homeostasis. Following influenza vaccination (N = 92), B-cell-derived cfDNA levels increased prior to elevated B-cell counts and predicted efficacy of antibody production. Patients with eosinophilic esophagitis (N = 21) and B-cell lymphoma (N = 27) showed selective elevation of eosinophil and B-cell cfDNA, respectively, which were undetectable by cell counts in blood. Immune-derived cfDNA provides a novel biomarker for monitoring immune responses to physiological and pathological processes that are not accessible using conventional methods.

2021 year in review: Spotlight on eosinophils

This review highlights recent advances in the understanding of eosinophils and eosinophilic diseases, particularly eosinophilic gastrointestinal diseases during the last year. The increasing incidence of diseases marked by eosinophilia has been documented and highlighted the need to understand eosinophil biology and eosinophilic contributions to disease. Significant insight into the nature of eosinophilic diseases has been achieved using next-generation sequencing technologies, proteomic analysis, and machine learning to analyze tissue biopsies. These technologies have elucidated mechanistic underpinnings of eosinophilic inflammation, delineated patient endotypes, and identified patient responses to therapeutic intervention. Importantly, recent clinical studies using mAbs that interfere with type 2 cytokine signaling or deplete eosinophils point to multiple and complex roles of eosinophils in tissues. Several studies identified distinct activation features of eosinophils in different tissues and disease states. The confluence of these studies supports a new paradigm of tissue-resident eosinophils that have pro- and anti-inflammatory immunomodulatory roles in allergic disease. Improved understanding of unique eosinophil activation states is now poised to identify novel therapeutic targets for eosinophilic diseases.

Desmoplakin and periplakin genetically and functionally contribute to eosinophilic esophagitis

Eosinophilic esophagitis (EoE) is a chronic allergic inflammatory disease with a complex underlying genetic etiology. Herein, we conduct whole-exome sequencing of a multigeneration EoE pedigree (discovery set) and 61 additional multiplex families with EoE (replication set). A series of rare, heterozygous, missense variants are identified in the genes encoding the desmosome-associated proteins DSP and PPL in 21% of the multiplex families. Esophageal biopsies from patients with these variants retain dilated intercellular spaces and decrease DSP and PPL expression even during disease remission. These variants affect barrier integrity, cell motility and RhoGTPase activity in esophageal epithelial cells and have increased susceptibility to calpain-14-mediated degradation. An acquired loss of esophageal DSP and PPL is present in non-familial EoE. Taken together, herein, we uncover a pathogenic role for desmosomal dysfunction in EoE, providing a deeper mechanistic understanding of tissue-specific allergic responses.

Metastasis-Entrained Eosinophils Enhance Lymphocyte-Mediated Antitumor Immunity

The recognition of the immune system as a key component of the tumor microenvironment (TME) led to promising therapeutics. Because such therapies benefit only subsets of patients, understanding the activities of immune cells in the TME is required. Eosinophils are an integral part of the TME especially in mucosal tumors. Nonetheless, their role in the TME and the environmental cues that direct their activities are largely unknown. We report that breast cancer lung metastases are characterized by resident and recruited eosinophils. Eosinophil recruitment to the metastatic sites in the lung was regulated by G protein-coupled receptor signaling but independent of CCR3. Functionally, eosinophils promoted lymphocyte-mediated antitumor immunity. Transcriptome and proteomic analyses identified the TME rather than intrinsic differences between eosinophil subsets as a key instructing factor directing antitumorigenic eosinophil activities. Specifically, TNFα/IFNγ-activated eosinophils facilitated CD4⁺ and CD8⁺ T-cell infiltration and promoted antitumor immunity. Collectively, we identify a mechanism by which the TME trains eosinophils to adopt antitumorigenic properties, which may lead to the development of eosinophil-targeted therapeutics. SIGNIFICANCE: These findings demonstrate antitumor activities of eosinophils in the metastatic tumor microenvironment, suggesting that harnessing eosinophil activity may be a viable clinical strategy in patients with cancer.

Aiolos regulates eosinophil migration into tissues

Expression of Ikaros family transcription factor IKZF3 (Aiolos) increases during murine eosinophil lineage commitment and maturation. Herein, we investigated Aiolos expression and function in mature human and murine eosinophils. Murine eosinophils deficient in Aiolos demonstrated gene expression changes in pathways associated with granulocyte-mediated immunity, chemotaxis, degranulation, ERK/MAPK signaling, and extracellular matrix organization; these genes had ATAC peaks within 1 kB of the TSS that were enriched for Aiolos-binding motifs. Global Aiolos deficiency reduced eosinophil frequency within peripheral tissues during homeostasis; a chimeric mouse model demonstrated dependence on intrinsic Aiolos expression by eosinophils. Aiolos deficiency reduced eosinophil CCR3 surface expression, intracellular ERK1/2 signaling, and CCL11-induced actin polymerization, emphasizing an impaired functional response. Aiolos-deficient eosinophils had reduced tissue accumulation in chemokine-, antigen-, and IL-13-driven inflammatory experimental models, all of which at least partially depend on CCR3 signaling. Human Aiolos expression was associated with active chromatin marks enriched for IKZF3, PU.1, and GATA-1-binding motifs within eosinophil-specific histone ChIP-seq peaks. Furthermore, treating the EOL-1 human eosinophilic cell line with lenalidomide yielded a dose-dependent decrease in Aiolos. These collective data indicate that eosinophil homing during homeostatic and inflammatory allergic states is Aiolos-dependent, identifying Aiolos as a potential therapeutic target for eosinophilic disease.

A novel class of TMPRSS2 inhibitors potently block SARS-CoV-2 and MERS-CoV viral entry and protect human epithelial lung cells

The host cell serine protease TMPRSS2 is an attractive therapeutic target for COVID-19 drug discovery. This protease activates the Spike protein of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and of other coronaviruses and is essential for viral spread in the lung. Utilizing rational structure-based drug design (SBDD) coupled to substrate specificity screening of TMPRSS2, we have discovered covalent small-molecule ketobenzothiazole (kbt) TMPRSS2 inhibitors which are structurally distinct from and have significantly improved activity over the existing known inhibitors Camostat and Nafamostat. Lead compound MM3122 (4) has an IC50 (half-maximal inhibitory concentration) of 340 pM against recombinant full-length TMPRSS2 protein, an EC50 (half-maximal effective concentration) of 430 pM in blocking host cell entry into Calu-3 human lung epithelial cells of a newly developed VSV-SARS-CoV-2 chimeric virus, and an EC50 of 74 nM in inhibiting cytopathic effects induced by SARS-CoV-2 virus in Calu-3 cells. Further, MM3122 blocks Middle East respiratory syndrome coronavirus (MERS-CoV) cell entry with an EC50 of 870 pM. MM3122 has excellent metabolic stability, safety, and pharmacokinetics in mice, with a half-life of 8.6 h in plasma and 7.5 h in lung tissue, making it suitable for in vivo efficacy evaluation and a promising drug candidate for COVID-19 treatment.

An interactive single cell web portal identifies gene and cell networks in COVID-19 host responses

Numerous studies have provided single-cell transcriptome profiles of host responses to SARS-CoV-2 infection. Critically lacking however is a data mine that allows users to compare and explore cell profiles to gain insights and develop new hypotheses. To accomplish this, we harmonized datasets from COVID-19 and other control condition blood, bronchoalveolar lavage, and tissue samples, and derived a compendium of gene signature modules per cell type, subtype, clinical condition, and compartment. We demonstrate approaches to interacting with, exploring, and functional evaluating these modules via a new interactive web portal ToppCell (http://toppcell.cchmc.org/). As examples, we develop three hypotheses: (1) alternatively-differentiated monocyte-derived macrophages form a multicelllar signaling cascade that drives T cell recruitment and activation; (2) COVID-19-generated platelet subtypes exhibit dramatically altered potential to adhere, coagulate, and thrombose; and (3) extrafollicular B maturation is driven by a multilineage cell activation network that expresses an ensemble of genes strongly associated with risk for developing post-viral autoimmunity.

Machine Learning Approach for Biopsy-Based Identification of Eosinophilic Esophagitis Reveals Importance of Global features

Goal

Eosinophilic esophagitis (EoE) is an allergic inflammatory condition characterized by eosinophil accumulation in the esophageal mucosa. EoE diagnosis includes a manual assessment of eosinophil levels in mucosal biopsies-a time-consuming, laborious task that is difficult to standardize. One of the main challenges in automating this process, like many other biopsy-based diagnostics, is detecting features that are small relative to the size of the biopsy.

Results

In this work, we utilized hematoxylin- and eosin-stained slides from esophageal biopsies from patients with active EoE and control subjects to develop a platform based on a deep convolutional neural network (DCNN) that can classify esophageal biopsies with an accuracy of 85%, sensitivity of 82.5%, and specificity of 87%. Moreover, by combining several downscaling and cropping strategies, we show that some of the features contributing to the correct classification are global rather than specific, local features.

Conclusions

We report the ability of artificial intelligence to identify EoE using computer vision analysis of esophageal biopsy slides. Further, the DCNN features associated with EoE are based on not only local eosinophils but also global histologic changes. Our approach can be used for other conditions that rely on biopsy-based histologic diagnostics.

Zooming in on T cell clones: Are we heading to personalized treatment of allergy?

Single-cell RNA and TCR sequencing of peripheral blood and esophageal cells of human eosinophilic esophagitis uncovers antigen-restricted T_H2 cells.

Epigenetic Analysis of the Chromatin Landscape Identifies a Repertoire of Murine Eosinophil-Specific PU.1-Bound Enhancers

Eosinophils develop in the bone marrow from hematopoietic progenitors into mature cells capable of a plethora of immunomodulatory roles via the choreographed process of eosinophilopoiesis. However, the gene regulatory elements and transcription factors (TFs) orchestrating this process remain largely unknown. The potency and resulting diversity fundamental to an eosinophil's complex immunomodulatory functions and tissue specialization likely result from dynamic epigenetic regulation of the eosinophil genome, a dynamic eosinophil regulome. In this study, we applied a global approach using broad-range, next-generation sequencing to identify a repertoire of eosinophil-specific enhancers. We identified over 8200 active enhancers located within 1-20 kB of expressed eosinophil genes. TF binding motif analysis revealed PU.1 (Spi1) motif enrichment in eosinophil enhancers, and chromatin immunoprecipitation coupled with massively parallel sequencing confirmed PU.1 binding in likely enhancers of genes highly expressed in eosinophils. A substantial proportion (>25%) of these PU.1-bound enhancers were unique to murine, culture-derived eosinophils when compared among enhancers of highly expressed genes of three closely related myeloid cell subsets (macrophages, neutrophils, and immature granulocytes). Gene ontology analysis of eosinophil-specific, PU.1-bound enhancers revealed enrichment for genes involved in migration, proliferation, degranulation, and survival. Furthermore, eosinophil-specific superenhancers were enriched in genes whose homologs are associated with risk loci for eosinophilia and allergic diseases. Our collective data identify eosinophil-specific enhancers regulating key eosinophil genes through epigenetic mechanisms (H3K27 acetylation) and TF binding (PU.1).

Functional role of kallikrein 5 and proteinase-activated receptor 2 in eosinophilic esophagitis

Eosinophilic esophagitis (EoE) is a chronic, food antigen-driven, inflammatory disease of the esophagus and is associated with impaired barrier function. Evidence is emerging that loss of esophageal expression of the serine peptidase inhibitor, kazal type 7 (SPINK7), is an upstream event in EoE pathogenesis. Here, we provide evidence that loss of SPINK7 mediates its pro-EoE effects via kallikrein 5 (KLK5) and its substrate, protease-activated receptor 2 (PAR2). Overexpression of KLK5 in differentiated esophageal epithelial cells recapitulated the effect of SPINK7 gene silencing, including barrier impairment and loss of desmoglein-1 expression. Conversely, KLK5 deficiency attenuated allergen-induced esophageal protease activity, modified commensal microbiome composition, and attenuated eosinophilia in a murine model of EoE. Inhibition of PAR2 blunted the cytokine production associated with loss of SPINK7 in epithelial cells and attenuated the allergen-induced esophageal eosinophilia in vivo. Clinical samples substantiated dysregulated PAR2 expression in the esophagus of patients with EoE, and delivery of the clinically approved drug α1 antitrypsin (A1AT, a protease inhibitor) inhibited experimental EoE. These findings demonstrate a role for the balance between KLK5 and protease inhibitors in the esophagus and highlight EoE as a protease-mediated disease. We suggest that antagonizing KLK5 and/or PAR2 has potential to be therapeutic for EoE.

Implicating Gene and Cell Networks Responsible for Differential COVID-19 Host Responses via an Interactive Single Cell Web Portal

Numerous studies have provided single-cell transcriptome profiles of host responses to SARS-CoV-2 infection. Critically lacking however is a datamine that allows users to compare and explore cell profiles to gain insights and develop new hypotheses. To accomplish this, we harmonized datasets from COVID-19 and other control condition blood, bronchoalveolar lavage, and tissue samples, and derived a compendium of gene signature modules per cell type, subtype, clinical condition, and compartment. We demonstrate approaches to probe these via a new interactive web portal (http://toppcell.cchmc.org/COVID-19). As examples, we develop three hypotheses: (1) a multicellular signaling cascade among alternatively differentiated monocyte-derived macrophages whose tasks include T cell recruitment and activation; (2) novel platelet subtypes with drastically modulated expression of genes responsible for adhesion, coagulation and thrombosis; and (3) a multilineage cell activator network able to drive extrafollicular B maturation via an ensemble of genes strongly associated with risk for developing post-viral autoimmunity.

A novel class of TMPRSS2 inhibitors potently block SARS-CoV-2 and MERS-CoV viral entry and protect human epithelial lung cells

The host cell serine protease TMPRSS2 is an attractive therapeutic target for COVID-19 drug discovery. This protease activates the Spike protein of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) and of other coronaviruses and is essential for viral spread in the lung. Utilizing rational structure-based drug design (SBDD) coupled to substrate specificity screening of TMPRSS2, we have discovered a novel class of small molecule ketobenzothiazole TMPRSS2 inhibitors with significantly improved activity over existing irreversible inhibitors Camostat and Nafamostat. Lead compound MM3122 ( 4 ) has an IC ₅₀ of 340 pM against recombinant full-length TMPRSS2 protein, an EC ₅₀ of 430 pM in blocking host cell entry into Calu-3 human lung epithelial cells of a newly developed VSV SARS-CoV-2 chimeric virus, and an EC ₅₀ of 74 nM in inhibiting cytopathic effects induced by SARS-CoV-2 virus in Calu-3 cells. Further, MM3122 blocks Middle East Respiratory Syndrome Coronavirus (MERS-CoV) cell entry with an EC ₅₀ of 870 pM. MM3122 has excellent metabolic stability, safety, and pharmacokinetics in mice with a half-life of 8.6 hours in plasma and 7.5 h in lung tissue, making it suitable for in vivo efficacy evaluation and a promising drug candidate for COVID-19 treatment.

A novel class of TMPRSS2 inhibitors potently block SARS-CoV-2 and MERS-CoV viral entry and protect human epithelial lung cells

The host cell serine protease TMPRSS2 is an attractive therapeutic target for COVID-19 drug discovery. This protease activates the Spike protein of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) and of other coronaviruses and is essential for viral spread in the lung. Utilizing rational structure-based drug design (SBDD) coupled to substrate specificity screening of TMPRSS2, we have discovered a novel class of small molecule ketobenzothiazole TMPRSS2 inhibitors with significantly improved activity over existing irreversible inhibitors Camostat and Nafamostat. Lead compound MM3122 ( 4 ) has an IC ₅₀ of 340 pM against recombinant full-length TMPRSS2 protein, an EC ₅₀ of 430 pM in blocking host cell entry into Calu-3 human lung epithelial cells of a newly developed VSV SARS-CoV-2 chimeric virus, and an EC ₅₀ of 74 nM in inhibiting cytopathic effects induced by SARS-CoV-2 virus in Calu-3 cells. Further, MM3122 blocks Middle East Respiratory Syndrome Coronavirus (MERS-CoV) cell entry with an EC ₅₀ of 870 pM. MM3122 has excellent metabolic stability, safety, and pharmacokinetics in mice with a half-life of 8.6 hours in plasma and 7.5 h in lung tissue, making it suitable for in vivo efficacy evaluation and a promising drug candidate for COVID-19 treatment.

Eosinophil Knockout Humans: Uncovering the Role of Eosinophils Through Eosinophil-Directed Biological Therapies

The enigmatic eosinophil has emerged as an exciting component of the immune system, involved in a plethora of homeostatic and inflammatory responses. Substantial progress has been achieved through experimental systems manipulating eosinophils in vivo, initially in mice and more recently in humans. Researchers using eosinophil knockout mice have identified a contributory role for eosinophils in basal and inflammatory processes and protective immunity. Primarily fueled by the purported proinflammatory role of eosinophils in eosinophil-associated diseases, a series of anti-eosinophil therapeutics have emerged as a new class of drugs. These agents, which dramatically deplete eosinophils, provide a valuable opportunity to characterize the consequences of eosinophil knockout humans. Herein, we comparatively describe mouse and human eosinophil knockouts. We put forth the view that human eosinophils negatively contribute to a variety of diseases and, unlike mouse eosinophils, do not yet have an identified role in physiological health; thus, clarifying all roles of eosinophils remains an ongoing pursuit.

Alpha 1 Antitrypsin is an Inhibitor of the SARS-CoV-2-Priming Protease TMPRSS2

BACKGROUND

Host proteases have been suggested to be crucial for dissemination of MERS, SARS-CoV, and SARS-CoV-2 coronaviruses, but the relative contribution of membrane versus intracellular proteases remains controversial. Transmembrane serine protease 2 (TMPRSS2) is regarded as one of the main proteases implicated in the coronavirus S protein priming, an important step for binding of the S protein to the angiotensin-converting enzyme 2 (ACE2) receptor before cell entry.

METHODS

We developed a cell-based assay to identify TMPRSS2 inhibitors. Inhibitory activity was established in SARS-CoV-2 viral load systems.

RESULTS

We identified the human extracellular serine protease inhibitor (serpin) alpha 1 anti-trypsin (A1AT) as a novel TMPRSS2 inhibitor. Structural modeling revealed that A1AT docked to an extracellular domain of TMPRSS2 in a conformation that is suitable for catalysis, resembling similar serine protease inhibitor complexes. Inhibitory activity of A1AT was established in a SARS-CoV-2 viral load system. Notably, plasma A1AT levels were associated with COVID-19 disease severity.

CONCLUSIONS

Our data support the key role of extracellular serine proteases in SARS CoV-2 infections and indicate that treatment with serpins, particularly the FDA-approved drug A1AT, may be effective in limiting SARS-CoV-2 dissemination by affecting the surface of the host cells.

Long-term Efficacy and Tolerability of RPC4046 in an Open-Label Extension Trial of Patients With Eosinophilic Esophagitis

BACKGROUND & AIMS

The short-term efficacy of RPC4046, a monoclonal antibody against interleukin-13, has been shown in patients with eosinophilic esophagitis (EoE). We investigated the long-term efficacy and safety of RPC4046 in an open-label, long-term extension (LTE) study in adults with EoE.

METHODS

We analyzed data from 66 patients who completed the 16-week, double-blind, induction portion of a phase 2 study of RPC4046 (180 mg or 360 mg/wk) vs placebo and then completed a 52-week LTE, receiving open-label RPC4046 360 mg/wk. The study was conducted at 28 centers in 3 countries; patients were enrolled between September 2014 and January 2017. Outcomes were stratified by double-blind dose group and included esophageal eosinophil counts, EoE endoscopic reference score, EoE histologic scoring system score, symptom-based EoE activity index score, and safety.

RESULTS

By week 12 of the LTE, esophageal eosinophil mean and peak counts, total EoE endoscopic reference scores, and EoE histologic scoring system grade and stage scores did not differ considerably between patients who originally received placebo vs RPC4046. Most patients maintained responses through week 52. Symptom remission (symptom-based EoE activity index score, ≤20) increased from 14% at LTE entry to 67% at LTE week 52 in placebo‒RPC4046 patients and from 30% to 54% in RPC4046‒RPC4046 (either dose) patients. Of the 28 patients who did not have a histologic response to RPC4046 during the double-blind induction phase, 10 patients (36%) achieved response during the LTE. The most common adverse events were upper respiratory tract infection (21%) and nasopharyngitis (14%).

CONCLUSIONS

One year of treatment with RPC4046 is generally well tolerated and results in continued improvement and/or maintenance of endoscopic, histologic, and clinical measures of EoE disease activity relative to baseline.

TRIAL REGISTRATION

NCT02098473.