TH2-driven manifestations of inborn errors of immunity.

Monogenic lesions in pathways critical for effector functions responsible for immune surveillance, protection against autoinflammation, and appropriate responses to allergens and microorganisms underlie the pathophysiology of inborn errors of immunity (IEI). Variants in cytokine production, cytokine signaling, epithelial barrier function, antigen presentation, receptor signaling, and cellular processes and metabolism can drive autoimmunity, immunodeficiency, and/or allergic inflammation. Identification of these variants has improved our understanding of the role that many of these proteins play in skewing toward TH2-related allergic inflammation. Early-onset or atypical atopic disease, often in conjunction with immunodeficiency and/or autoimmunity, should raise suspicion for an IEI. This becomes a diagnostic dilemma if the initial clinical presentation is solely allergic inflammation, especially when the prevalence of allergic diseases is becoming more common. Genetic sequencing is necessary for IEI diagnosis and is helpful for early recognition and implementation of targeted treatment, if available. Although genetic evaluation is not feasible for all patients with atopy, identifying atopic patients with molecular immune abnormalities may be helpful for diagnostic, therapeutic, and prognostic purposes. In this review, we focus on IEI associated with TH2-driven allergic manifestations and classify them on the basis of the affected molecular pathways and predominant clinical manifestations.

Mepolizumab incompletely suppresses clinical flares in a pilot study of episodic angioedema with eosinophilia.

BACKGROUND: Episodic angioedema with eosinophilia (EAE) is a rare multilineage cyclic syndrome of unknown etiology characterized by episodes of angioedema, myalgia, fatigue, and fever that occur every 3 to 8 weeks and resolve between episodes without therapy. Cyclic elevations in serum IL-5 levels and neutrophils precede the increase in absolute eosinophil count (AEC) in most patients. OBJECTIVE: We sought to assess the role of IL-5-driven eosinophilia in the clinical manifestations of EAE. METHODS: An open-label pilot study of mepolizumab (700 mg intravenously monthly for 3 months followed by sequential dose reduction to the Food and Drug Administration-approved dose of 300 mg subcutaneously monthly) was conducted. The primary end point was reduction in the number and severity of clinical symptoms as assessed by patient-reported symptom questionnaires. Secondary end points were greater than or equal to 75% reduction in peak AEC after 1 dose of mepolizumab and sustained reduction in AEC after 3 doses of mepolizumab. Exploratory end points included effects of mepolizumab treatment on other cell lineages (numbers and surface marker expression), levels of plasma mediators, and biomarkers of eosinophil activation. RESULTS: Four female and 1 male (median age, 45 years) participants with EAE were enrolled. None of the 5 participants experienced a reduction in the number of symptomatic flares on mepolizumab therapy, and 1 participant withdrew before study completion because of lack of improvement. Peak AEC was reduced by 75% or more in 3 participants after the first dose of mepolizumab and in 4 participants after 3 doses. CONCLUSIONS: In a small cohort of participants with EAE, mepolizumab was unsuccessful in substantially reducing clinical symptoms despite reduction in AEC.

Clinical and molecular correlates of the Index of Severity for Eosinophilic Esophagitis.

BACKGROUND: The Index of Severity for Eosinophilic Esophagitis (I-SEE) is a new expert-defined clinical tool that classifies disease severity of eosinophilic esophagitis (EoE). OBJECTIVE: We aimed to determine whether I-SEE is associated with patient characteristics, molecular features of EoE, or both. METHODS: We analyzed a prospective cohort of patients with EoE from the Consortium of Eosinophilic Gastrointestinal Disease Researchers (CEGIR). Associations between I-SEE and clinical and molecular features (assessed by an EoE diagnostic panel [EDP]) were assessed. RESULTS: In 318 patients with chronic EoE (209 adults, 109 children), median total I-SEE score was 7.0, with a higher symptoms and complications score in children than adults (4.0 vs 1.0; P < .001) and higher inflammatory and fibrostenotic features scores in adults than children (3.0 vs 1.0 and 3.0 vs 0, respectively; both P < .001). Total I-SEE score had a bimodal distribution with the inactive to moderate categories and severe category. EDP score correlated with total I-SEE score (r = -0.352, P < .001) and both inflammatory and fibrostenotic features scores (r = -0.665, P < .001; r = -0.446, P < .001, respectively), but not with symptoms and complications scores (r = 0.047, P = .408). Molecular severity increased from inactive to mild and moderate, but not severe, categories. Longitudinal changes of modified I-SEE scores and inflammatory and fibrostenotic features scores reflected histologic and molecular activity. CONCLUSIONS: I-SEE score is associated with select clinical features across severity categories and with EoE molecular features for nonsevere categories, warranting further validation.

New considerations of health disparities within allergy and immunology.

The pandemic, political upheavals, and social justice efforts in our society have resulted in attention to persistent health disparities and the urgent need to address them. Using a scoping review, we describe published updates to address disparities and targets for interventions to improve gaps in care within allergy and immunology. These disparities-related studies provide a broad view of our current understanding of how social determinants of health threaten patient outcomes and our ability to advance health equity efforts in our field. We outline next steps to improve access to care and advance health equity for patients with allergic/immunologic diseases through actions taken at the individual, community, and policy levels, which could be applied outside of our field. Key among these are efforts to increase the diversity among our trainees, providers, and scientific teams and enhancing efforts to participate in advocacy work and public health interventions. Addressing health disparities requires advancing our understanding of the interplay between social and structural barriers to care and enacting the needed interventions in various key areas to effect change.

Anti-Siglec-8 Antibody for Eosinophilic Gastritis and Duodenitis.

BACKGROUND: Eosinophilic gastritis and duodenitis are characterized by gastrointestinal mucosal eosinophilia, chronic symptoms, impaired quality of life, and a lack of adequate treatments. Mast-cell activity may contribute to the pathogenesis of the conditions. AK002 (lirentelimab) is an anti-Siglec-8 antibody that depletes eosinophils and inhibits mast cells and that has shown potential in animal models as a treatment for eosinophilic gastritis and duodenitis. METHODS: In this phase 2 trial, we randomly assigned adults who had symptomatic eosinophilic gastritis, eosinophilic duodenitis, or both conditions in a 1:1:1 ratio to receive four monthly infusions of low-dose AK002, high-dose AK002, or placebo. The primary end point was the change in gastrointestinal eosinophil count from baseline to 2 weeks after the final dose; to maximize statistical power, we evaluated this end point in the placebo group as compared with the combined AK002 group. Secondary end points were treatment response (>30% reduction in total symptom score and >75% reduction in gastrointestinal eosinophil count) and the change in total symptom score. RESULTS: Of the 65 patients who underwent randomization, 43 were assigned to receive AK002 and 22 were assigned to receive placebo. The mean percentage change in gastrointestinal eosinophil count was -86% in the combined AK002 group, as compared with 9% in the placebo group (least-squares mean difference, -98 percentage points; 95% confidence interval [CI], -121 to -76; P<0.001). Treatment response occurred in 63% of the patients who received AK002 and in 5% of the patients who received placebo (difference, 58 percentage points; 95% CI, 36 to 74; P<0.001). The mean change in total symptom score was -48% with AK002 and -22% with placebo (least-squares mean difference, -26 percentage points; 95% CI, -44 to -9; P = 0.004). Adverse events associated with AK002 were similar to those with placebo, with the exception of higher percentages of patients having mild-to-moderate infusion-related reactions with AK002 (60% in the combined AK002 group and 23% in the placebo group). CONCLUSIONS: In patients with eosinophilic gastritis or duodenitis, AK002 reduced gastrointestinal eosinophils and symptoms. Infusion-related reactions were more common with AK002 than with placebo. (Funded by Allakos; ENIGMA ClinicalTrials.gov number, NCT03496571.).

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.

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.

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.

Distinct CRTH2+CD161+ (peTh2) memory CD4+ T-cell cytokine profiles in food allergy and eosinophilic gastrointestinal disorders.

INTRODUCTION: Although IgE-mediated food allergy (FA) and eosinophilic gastrointestinal disorders (EGID) are clinically distinct and treated differently, pathogenic effector Th2 (peTh2) cells are implicated in the pathogenesis of both FA and EGID. The aim of this study was to better characterize peTh2 cells in the context of FA and EGID and the overlap between these two conditions. METHODS: Peripheral blood peTh2 cells (CD3+CD4+CD27-CD49d+CRTH2+CD161+) were profiled by intracellular cytokine flow cytometry in the following patient cohorts: patients with FA alone (n = 8), FA and food-triggered EGID (EGID+FA+FT, n = 7), food-triggered EGID alone (EGID+FT, n = 7), EGID without FA or specific food triggers (ONLY_EGID, n = 9), and healthy volunteers (HV, n = 7). Overnight peripheral blood mononuclear cell (PBMC) culture supernatants were assessed for cytokine production by multiplex analysis. RESULTS: CRTH2+CD161+ (peTh2) memory CD4+ T cells were significantly increased in both patients with FA and those with ALL_EGID (inclusive of EGID+FA+FT, EGID+FT and ONLY_EGID) when compared to HV. However, ALL_EGID patients, particularly those with EGID+FA+FT, had significantly elevated IL-5+IL-13+ peTh2 cells, whereas FA patients had significantly elevated IFN-γ or IL-17A-expressing peTh2 cells. This finding was supported by increased spontaneous IL-5 and IL-13 production in overnight cultures of PBMC from EGID+FA+FT patients compared to spontaneous IL-10 and IFN-γ production by PBMC from FA patients. FA patients had increased IL-9, IL-10, IL-17A, and IFN-γ production in overnight cultures of stimulated PBMC. CONCLUSIONS: EGID and IgE-mediated FA share a common cell subtype defined by specific surface markers and termed CRTH2+CD161+ (peTh2) memory CD4+ T cells. However, the cytokine profiles of these CRTH2+CD161+ (peTh2) memory CD4+ T cells are markedly different between the two disorders.

Urine eosinophil-derived neurotoxin: A potential marker of activity in select eosinophilic disorders.

BACKGROUND: Biomarkers of eosinophilic disease activity, especially in the context of novel therapies that reduce blood eosinophil counts, are an unmet need. Absolute eosinophil count (AEC) does not accurately reflect tissue eosinophilia or eosinophil activation. Therefore, the aims of this study were to compare the reliability of plasma and urine eosinophil major basic protein 1, eosinophil cationic protein, eosinophil-derived neurotoxin (EDN), and eosinophil peroxidase measurement and to evaluate the usefulness of eosinophil granule protein (EGP) measurement for the assessment of disease activity in patients with eosinophil-associated diseases treated with mepolizumab, benralizumab, or dexpramipexole. METHODS: Eosinophil granule protein concentrations were measured in serum, plasma, and urine from healthy volunteers and patients with hypereosinophilic syndrome (HES), eosinophilic granulomatosis with polyangiitis (EGPA), and eosinophilic asthma using a multiplex assay. RESULTS: Urine EGP concentrations remained stable, whereas serum and plasma EGP concentrations increased significantly with delayed processing. Plasma (p) EDN, but not urine (u) EDN, concentration correlated with AEC and negatively correlated with prednisone dose. Both pEDN and uEDN decreased significantly following treatment of HES patients with benralizumab and EGPA patients with mepolizumab. uEDN appeared to increase with clinical relapse in both patient groups. CONCLUSIONS: Measurement of EGP in urine is noninvasive and unaffected by cellular lysis. Although plasma and urine EDN concentrations showed a similar pattern following benralizumab and mepolizumab treatment, the lack of correlation between AEC or prednisone dose and uEDN concentrations suggests that measurement of uEDN may provide a potential biomarker of disease activity in patients with HES and EGPA.

Artificial Intelligence: Exploring the Future of Innovation in Allergy Immunology.

PURPOSE OF REVIEW: Artificial intelligence (AI) has increasingly been used in healthcare. Given the capacity of AI to handle large data and complex relationships between variables, AI is well suited for applications in healthcare. Recently, AI has been applied to allergy research. RECENT FINDINGS: In this article, we review how AI technologies have been utilized in basic science and clinical allergy research for asthma, atopic dermatitis, rhinology, adverse reactions to drugs and vaccines, food allergy, anaphylaxis, urticaria, and eosinophilic gastrointestinal disorders. We discuss barriers for AI adoption to improve the care of patients with atopic diseases. These studies demonstrate the utility of applying AI to the field of allergy to help investigators expand their understanding of disease pathogenesis, improve diagnostic accuracy, enable prediction for treatments and outcomes, and for drug discovery.

False-Negative Testing for FIP1L1::PDGFRA by Fluorescence in situ Hybridization Is a Frequent Cause of Diagnostic Delay.

The imatinib-sensitive fusion gene FIP1L1::PDGFRA is the most frequent molecular abnormality identified in patients with eosinophilic myeloid neoplasms. Rapid recognition of this mutation is essential given the poor prognosis of PDGFRA-associated myeloid neoplasms prior to the availability of imatinib therapy. We report a case of a patient in whom delayed diagnosis resulted in cardiac transplantation for eosinophilic endomyocardial fibrosis. The delay in diagnosis was due, in part, to a false-negative result in fluorescence in situ hybridization (FISH) testing for FIP1L1::PDGFRA. To explore this further, we examined our cohort of patients presenting with confirmed or suspected eosinophilic myeloid neoplasms and found 8 additional patients with negative FISH results despite a positive reverse-transcriptase polymerase chain reaction test for FIP1L1::PDGFRA. More importantly, false-negative FISH results delayed the median time to imatinib treatment by 257 days. These data emphasize the importance of empiric imatinib therapy in patients with clinical features suggestive of PDGFRA-associated disease.

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.

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.

Benralizumab for PDGFRA-Negative Hypereosinophilic Syndrome.

BACKGROUND: Hypereosinophilic syndrome is a group of diseases defined by marked eosinophilia in blood or tissue and eosinophil-related clinical manifestations. Benralizumab is a monoclonal antibody against interleukin-5 receptor α, which is expressed on human eosinophils. METHODS: In this randomized, double-blind, placebo-controlled, phase 2 trial, we administered a series of three monthly subcutaneous injections of either benralizumab (at a dose of 30 mg) or placebo in 20 symptomatic patients who had PDGFRA-negative hypereosinophilic syndrome and an absolute eosinophil count of at least 1000 cells per cubic millimeter; all the patients were receiving stable therapy (drugs or dietary changes) for this disease. This regimen was followed by an open-label phase, during which the patient's background therapy could be tapered as tolerated, and an extension phase. The primary end point of the randomized phase was a reduction of at least 50% in the absolute eosinophil count at week 12. RESULTS: During the randomized phase, the primary end point occurred in more patients in the benralizumab group than in the placebo group (9 of 10 patients [90%] vs. 3 of 10 patients [30%], P = 0.02). During the open-label phase, clinical and hematologic responses were observed in 17 of 19 patients (89%) and were sustained for 48 weeks in 14 of 19 patients (74%); in the latter group, in 9 of 14 patients (64%), background therapies could be tapered. Bone marrow and tissue eosinophilia were also suppressed with benralizumab therapy. The most common drug-related adverse events, headache and an elevated lactate dehydrogenase level, occurred in 32% of the patients after the first dose of benralizumab and resolved within 48 hours in all patients. Other adverse events occurred with similar frequency in the two groups. Of the many potential predictors of response that were examined, only clinical disease subtype appeared to be associated with the initial response or relapse. CONCLUSIONS: In this small phase 2 trial, patients with PDGFRA-negative hypereosinophilic syndrome who received benralizumab for 12 weeks had lower absolute eosinophil counts than those who received placebo. During the open-label phase, clinical and hematologic responses were sustained for 48 weeks in 74% of the patients. Adverse events did not limit treatment. (Funded by the National Institute of Allergy and Infectious Diseases; ClinicalTrials.gov numbers, NCT00001406 and NCT02130882.).

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.

Prospective Endoscopic Activity Assessment for Eosinophilic Gastritis in a Multisite Cohort.

INTRODUCTION: Eosinophilic gastritis (EG) is a chronic inflammatory disease of the stomach characterized by eosinophil-predominant gastric mucosal inflammation and gastrointestinal symptoms. The aim of this study was to prospectively evaluate endoscopic features in a large series of children and adults with EG to better understand the endoscopic manifestations and develop a standardized instrument for investigations. METHODS: Data were prospectively collected as part of the Consortium for Eosinophilic Gastrointestinal Disease Researchers, a national collaborative network. Endoscopic features were prospectively recorded using a system specifically developed for EG, the EG Endoscopic Reference System (EG-REFS). Correlations were made between EG-REFS and clinical and histologic features. RESULTS: Of 98 patients with EG, 65 underwent assessments using EG-REFS. The most common findings were erythema (72%), raised lesions (49%), erosions (46%), and granularity (35%); only 8% of patients with active histology (≥30 eosinophils/high-power field) exhibited no endoscopic findings. A strong correlation between EG-REFS scores and physician global assessment of endoscopy severity was demonstrated (Spearman r = 0.84, P < 0.0001). The overall score and specific components of EG-REFS were more common in the antrum than in the fundus or body. EG-REFS severity was significantly correlated with active histology, defined by a threshold of ≥30 eosinophils/high-power field (P = 0.0002). DISCUSSION: Prospective application of EG-REFS identified gastric features with a strong correlation with physician global assessment of endoscopic activity in EG. Endoscopic features demonstrated greater severity in patients with active histology and a predilection for the gastric antrum. Further development of EG-REFS should improve its utility in clinical studies.

Pulmonary Eosinophilic Granulomatosis with Polyangiitis Has IgG4 Plasma Cells and Immunoregulatory Features.

The immunologic mechanisms promoting eosinophilic granulomatosis with polyangiitis (EGPA) are unclear. To characterize the mechanisms underlying pulmonary EGPA, we examined and compared EGPA paraffin-embedded lung biopsies with normal lung biopsies, using immunostaining, RNA sequencing, and RT-PCR. The results revealed novel type 2 as well as immuneregulatory features. These features included basophils and increased mast cell contents; increased immunostaining for tumor necrosis factor ligand superfamily member 14; sparse mast cell degranulation; numerous forkhead box protein P3 (FoxP3)+ regulatory T cells and IgG4 plasma cells; and abundant arachidonate 15-lipoxygenase and 25-hydroxyvitamin D-1 α hydroxylase, mitochondrial. Significantly decreased 15-hydroxyprostaglandin dehydrogenase [NAD(+)], which degrades eicosanoids, was observed in EGPA samples. In addition, there was significantly increased mRNA for chemokine (C-C motif) ligands 18 and 13 and major collagen genes, IgG4-rich immune complexes coating alveolar macrophages, and increased immunostaining for phosphorylated mothers against decapentaplegic homolog 2/SMAD2, suggesting transforming growth factor-ß activation. These findings suggest a novel self-promoting mechanism of activation of alveolar macrophages by arachidonate 15-lipoxygenase-derived eicosanoids to express chemokines that recruit a combined type 2/immunoregulatory immune response, which produces these eicosanoids. These results suggest that the pulmonary EGPA immune response resembles the immune response to a tissue-invasive parasite infection.

Mepolizumab or Placebo for Eosinophilic Granulomatosis with Polyangiitis.

BACKGROUND: Eosinophilic granulomatosis with polyangiitis is an eosinophilic vasculitis. Mepolizumab, an anti-interleukin-5 monoclonal antibody, reduces blood eosinophil counts and may have value in the treatment of eosinophilic granulomatosis with polyangiitis. METHODS: In this multicenter, double-blind, parallel-group, phase 3 trial, we randomly assigned participants with relapsing or refractory eosinophilic granulomatosis with polyangiitis who had received treatment for at least 4 weeks and were taking a stable prednisolone or prednisone dose to receive 300 mg of mepolizumab or placebo, administered subcutaneously every 4 weeks, plus standard care, for 52 weeks. The two primary end points were the accrued weeks of remission over a 52-week period, according to categorical quantification, and the proportion of participants in remission at both week 36 and week 48. Secondary end points included the time to first relapse and the average daily glucocorticoid dose (during weeks 48 through 52). The annualized relapse rate and safety were assessed. RESULTS: A total of 136 participants underwent randomization, with 68 participants assigned to receive mepolizumab and 68 to receive placebo. Mepolizumab treatment led to significantly more accrued weeks of remission than placebo (28% vs. 3% of the participants had ≥24 weeks of accrued remission; odds ratio, 5.91; 95% confidence interval [CI], 2.68 to 13.03; P<0.001) and a higher percentage of participants in remission at both week 36 and week 48 (32% vs. 3%; odds ratio, 16.74; 95% CI, 3.61 to 77.56; P<0.001). Remission did not occur in 47% of the participants in the mepolizumab group versus 81% of those in the placebo group. The annualized relapse rate was 1.14 in the mepolizumab group, as compared with 2.27 in the placebo group (rate ratio, 0.50; 95% CI, 0.36 to 0.70; P<0.001). A total of 44% of the participants in the mepolizumab group, as compared with 7% of those in the placebo group, had an average daily dose of prednisolone or prednisone of 4.0 mg or less per day during weeks 48 through 52 (odds ratio, 0.20; 95% CI, 0.09 to 0.41; P<0.001). The safety profile of mepolizumab was similar to that observed in previous studies. CONCLUSIONS: In participants with eosinophilic granulomatosis with polyangiitis, mepolizumab resulted in significantly more weeks in remission and a higher proportion of participants in remission than did placebo, thus allowing for reduced glucocorticoid use. Even so, only approximately half the participants treated with mepolizumab had protocol-defined remission. (Funded by GlaxoSmithKline and the National Institute of Allergy and Infectious Diseases; ClinicalTrials.gov number, NCT02020889 .).

Dexpramipexole as an oral steroid-sparing agent in hypereosinophilic syndromes.

Hypereosinophilic syndromes (HESs) are a heterogeneous group of disorders characterized by peripheral eosinophilia and eosinophil-related end organ damage. Whereas most patients respond to glucocorticoid (GC) therapy, high doses are often necessary, and side effects are common. Dexpramipexole (KNS-760704), an orally bioavailable synthetic aminobenzothiazole, showed an excellent safety profile and was coincidentally noted to significantly decrease absolute eosinophil counts (AECs) in a phase 3 trial for amyotrophic lateral sclerosis. This proof-of-concept study was designed to evaluate dexpramipexole (150 mg orally twice daily) as a GC-sparing agent in HESs. Dual primary end points were (1) the proportion of subjects with ≥50% decrease in the minimum effective GC dose (MED) to maintain AEC <1000/µL and control clinical symptoms, and (2) the MED after 12 weeks of dexpramipexole (MEDD) as a percentage of the MED at week 0. Out of 10 subjects, 40% (95% confidence interval [CI], 12%, 74%) achieved a ≥50% reduction in MED, and the MEDD/MED ratio was significantly <100% (median, 66%; 95% CI, 6%, 98%; P = .03). All adverse events were self-limited, and none led to drug discontinuation. Affected tissue biopsy samples in 2 subjects showed normalization of pathology and depletion of eosinophils on dexpramipexole. Bone marrow biopsy samples after 12 weeks of dexpramipexole showed selective absence of mature eosinophils in responders. Dexpramipexole appears promising as a GC-sparing agent without apparent toxicity in a subset of subjects with GC-responsive HESs. Although the exact mechanism of action is unknown, preliminary data suggest that dexpramipexole may affect eosinophil maturation in the bone marrow. This study was registered at www.clinicaltrials.gov as #NCT02101138.