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Background: Hypereosinophilic syndromes (HES) are defined as hypereosinophilia with eosinophil-related clinical manifestations, some of which overlap in presentation with asthma, atopic dermatitis, eosinophilic esophagitis, and/or chronic rhinosinusitis with nasal polyps. Dupilumab is approved to treat these conditions but can induce a transient rise in the absolute eosinophil count and rare eosinophil-related complications., Objective: To determine whether eosinophil-related complications of dupilumab are increased in HES., Methods: Retrospective chart review of patients with HES treated with dupilumab enrolled on an institutional review board-approved research protocol at the National Institutes of Health (NCT00001406) or receiving care at Walter Reed National Military Medical Center. Clinical response and treatment-emergent adverse events were recorded. Serum mediators were assessed in a subset of patients before and after dupilumab using stored samples., Results: Among the 28 patients (15 male, 13 female; median age 41.5 y), the most common prescribing indication for dupilumab was chronic rhinosinusitis with nasal polyps (n = 11). Twenty-three patients (82%) showed significant clinical improvement on dupilumab. Hypereosinophilia (absolute eosinophil count > 1.5 × 10 9 /L) recurred or worsened in 9 of 20 patients on dupilumab monotherapy. Moreover, 4 of 20 (20%) patients developed an eosinophil-related complication with dupilumab discontinuation and/or addition of eosinophil-lowering therapy. None of the 8 patients who received dupilumab while in hematological remission on an eosinophil-lowering biologic developed hypereosinophilia or an eosinophil-related complication. Serum immunoglobulin E and eotaxin levels decreased on dupilumab therapy., Conclusions: These data suggest that dupilumab is effective in treating residual symptoms in HES patients but that the incidence of eosinophil-related complications is increased. Concomitant eosinophil-lowering therapy may reduce the risk of eosinophil-related complications during dupilumab therapy in patients with HES., (Published by Elsevier Inc.)

Hypereosinophilic syndrome (HES) and eosinophilic granulomatosis with polyangiitis (EGPA) are complex disorders defined by blood and tissue eosinophilia and heterogeneous clinical manifestations. Historically, the mainstay of therapy for both conditions has been systemic glucocorticoids. However, recent availability of biologics that directly or indirectly target eosinophils has provided new avenues to pursue improved outcomes with decreased toxicity. In this article, we summarize the evidence supporting the use of specific biologics in HES and/or EGPA and provide a framework for their clinical use in patients., Competing Interests: Disclosure The authors have nothing to disclose. This work was supported in part by the Division of Intramural Research, NIAID, NIH., (Published by Elsevier Inc.)

The Consortium of Eosinophilic Gastrointestinal disease Researchers (CEGIR) and The International Gastrointestinal Eosinophil Researchers (TIGERs) organized a daylong symposium at the 2024 annual meeting of the American Academy of Allergy, Asthma & Immunology. The symposium featured new discoveries in basic and translational research as well as debates on the mechanisms and management of eosinophilic gastrointestinal diseases. Updates on recent clinical trials and consensus guidelines were also presented. We summarize the updates on eosinophilic gastrointestinal diseases presented at the symposium., Competing Interests: Disclosure statement Supported by U54AI117804 (Consortium of Eosinophilic Gastrointestinal Disease Researchers), which is part of the Rare Disease Clinical Research Network (RDCRN), an initiative of the Office of Rare Disease Research (ORDR), National Center for Advancing Translational Sciences (NCATS), and is funded through collaboration between National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH)/National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), NCATS, and in part by the Division of Intramural Research, NIAID/NIH. CEGIR is also supported by patient advocacy groups including American Partnership for Eosinophilic Disorders (APFED), Campaign Urging Research for Eosinophilic Diseases (CURED), and Eosinophilic Family Coalition (EFC). As a member of the RDCRN, CEGIR is also supported by its Data Management and Coordinating Center (DMCC) (U2CTR002818). Funding support for the DMCC is provided by the NCATS and the National Institute of Neurological Disorders and Stroke (NINDS). B.L.W. was funded by NIH/NIAID (K23AI158813). E.M.A. was funded by the NIH (KL2TR002552, K12TR004410). S.S.A. was funded by NIH/NIDDK (R56AI092135). S.J.A. was funded by NIH/National Heart, Lung, and Blood Institute (NHLBI) (R01HL153170). D.A.H. was directly supported by the Hartwell Foundation, the Food Allergy Fund, and a faculty development award from the American Academy of Allergy, Asthma & Immunology. Allergy research in the Hill laboratory was supported by NIH/NHLBI (R01HL162715) and the Children’s Hospital of Philadelphia Research Institute. J.W.C. was supported by the NIH (K23DK129784). F.L.K. was funded by APFED HOPE Pilot Grant 2023 and NIH/NIAID K23AI171085. M.A.R. was funded by the NIH (K08AI148456). L.A.S. was supported by NIH/NIAID (R01AI168134). The contents are those of the authors and do not necessarily represent the official views or an endorsement by the NIH or other funders. None of the funding sources had a role in the design or conduct of the study. Disclosure of potential conflict of interest: B. L. Wright reports in-kind support from Regeneron in the form of study drug (dupilumab and placebo) for a clinical trial of milk oral immunotherapy. J. P. Abonia reports receipt of payment or honoraria for lectures from Takeda Global Research and Development; participation on a data safety monitoring board for OctaPharma USA; and receipt of grants or contracts from Cures Within Reach and Celgene. E. M. Abud is coinventor of patent WO/2018/160496 (microglia differentiation and use); serves as advisory board member and consulting agreements with StemPharm and Neucyte; and reports advisory board participation for Amgen and AstraZeneca. S. S. Aceves is coinventor of oral viscous budesonide, patented by the University of California, San Diego, and licensed by Takeda (oral budesonide suspension); has acted as speaker for Regeneron/Sanofi; and has received research funding from Bristol Myers Squibb. S. J. Ackerman is chief science officer and executive board member of EnteroTrack; has received patents on the Esophageal String Test (EST); has consulted for Areteia Pharmaceuticals; and has participated on the medical advisory panel of the American Partnership for Eosinophilic Disorders (APFED). M. Braskett reports acting as scientific advisor to Bryn Pharma; and receipt of royalties from UpToDate. J. W. Chang reports consulting for Regeneron/Sanofi, Takeda, and Bristol Myers Squibb. M. Chehade reports consulting for Regeneron/Sanofi, Adare/Ellodi, AstraZeneca, Bristol Myers Squibb, Allakos, Shire/Takeda, Phathom, and Recludix Pharma; and receipt of research funding from Regeneron, Allakos, AstraZeneca, Adare/Ellodi, Bristol Myers Squibb, Danone, and Shire/Takeda. G. M. Constantine reports speaker honoraria from PeerView CME. C. M. Davis reports research funding from NIH/NIAID, DBV, Regeneron, AstraZeneca, Takeda, and Allergenis; and educational funding from Genentech. E. S. Dellon reports research funding from Adare/Ellodi, Allakos, Arena/Pfizer, AstraZeneca, Eupraxia, Ferring, GSK, Meritage, Miraca, Nutricia, Celgene/Receptos/BMS, Regeneron, Revolo, and Shire/Takeda; consulting for Abbott, AbbVie, Adare/Ellodi, Aimmune, Akesobio, Alfasigma, ALK, Allakos, Amgen, Apollo, Aqilion, Arena/Pfizer, Aslan, AstraZeneca, Avir, Biorasi, Bryn, Calypso, Celgene/Receptos/BMS, Celldex, Eli Lilly, EsoCap, Eupraxia, Dr Falk Pharma, Ferring, GSK, Gossamer Bio, Holoclara, Invea, Knightpoint, Landos, LucidDx, Morphic, Nexstone Immunology/Uniquity, Nutricia, Parexel/Calyx, Phathom, Regeneron, Revolo, Robarts/Alimentiv, Salix, Sanofi, Shire/Takeda, Target RWE, and Upstream Bio; and receipt of educational grants from Allakos, Aqilion, Holoclara, and Invea. R. Durban reports consulting for Sanofi, AstraZeneca, Reckitt/Mead Johnson Nutrition, Abbott Nutrition, and Nutricia North America. D. A. Hill has received a patent related to the utilization of food-specific T-cell responses for the diagnosis and management of EoE. E. T. Jensen reports consulting fees from Regeneron, Jazz Pharmaceuticals, and TARGET-RWE. A. Kewalramani reports sitting on the Sanofi Mid-Atlantic Regional Respiratory Field medical advisory board. P. Khoury and A. D. Klion report royalties from UpToDate. F. L. Kuang reports research funding from AstraZeneca. E. C. McGowan reports funding from NIH/NIAID and American College of Gastroenterology; and consulting for Regeneron/Sanofi and Takeda. J. M. Spergel reports grant support from the NIH, Regeneron/Sanofi, and Novartis; and has consulted for Regeneron/Sanofi, Allakos, Readysetfood, Novartis, and Bristol Myers Squibb. A. M. Uchida reports consulting for Regeneron/Sanofi, Takeda, and AstraZeneca. J. B. Wechslerc reports consulting for Allakos, Ellodi, Regeneron/Sanofi/Genzyme, Bristol Myers Squibb, Invea Therapeutics, CellDex, and AstraZeneca; and clinical trial/research funding from Allakos and Regeneron/Sanofi. R. D. Pesek reports consulting for Regeneron. The rest of the authors declare that they have no relevant conflicts of interest., (Copyright © 2024 American Academy of Allergy, Asthma & Immunology. All rights reserved.)

Rare eosinophil-associated disorders (EADs), including hypereosinophilic syndrome, eosinophilic granulomatosis with polyangiitis, and eosinophilic gastrointestinal disorders, are a heterogeneous group of conditions characterized by blood and/or tissue hypereosinophilia and eosinophil-related clinical manifestations. Although the recent availability of biologic therapies that directly and indirectly target eosinophils has the potential to dramatically improve treatment options for all EADs, clinical trials addressing their safety and efficacy in rare EADs have been relatively few. Consequently, patient access to therapy is limited for many biologics, and the establishment of evidence-based treatment guidelines has been extremely difficult. In this regard, multicenter retrospective collaborative studies focusing on disease manifestations and treatment responses in rare EADs have provided invaluable data for physicians managing patients with these conditions and helped identify important questions for future translational research. During the Clinical Pre-Meeting Workshop held in association with the July 2023 biennial meeting of the International Eosinophil Society in Hamilton, Ontario, Canada, the successes and limitations of pivotal multicenter retrospective studies in EADs were summarized and unmet needs regarding the establishment of guidelines for use of biologics in rare EADs were discussed. Key topics of interest included (1) clinical outcome measures, (2) minimally invasive biomarkers of disease activity, (3) predictors of response to biologic agents, and (4) long-term safety of eosinophil depletion. Herein, we report a summary of these discussions, presenting a state-of-the-art overview of data currently available for each of these topics, the limitations of the data, and avenues for future data generation through implementation of multidisciplinary and multicenter studies., Competing Interests: Conflict of interest statement. F.R. receives consultancy and/or speaker fees from GlaxoSmithKline, AstraZeneca, Menarini, and Merck. F.L.K. receives research funding from AstraZeneca and speaker fees from both AstraZeneca and GlaxoSmithKline. S.J.A. is the Chief Scientific Officer and an Executive Board member of EnteroTrack, LLC; a co-inventor and holds patents on the Esophageal String Test; and a consultant for Areteia Pharmaceuticals. P.A. has received consulting fees and research support from AstraZeneca, GlaxoSmithKline, and Sanofi and research support from Regeneron. B.S.B. receives remuneration for serving on the scientific advisory board of Allakos, Inc.; owns stock in Allakos; currently serves as a consultant for Third Harmonic Bio and Sanofi/Regeneron; receives publication-related royalty payments from Elsevier and UpToDate; is a co-inventor on existing Siglec-8–related patents and thus may be entitled to a share of royalties received by Johns Hopkins University during development and potential sales of such products; and is a co-founder of Allakos, which makes him subject to certain restrictions under university policy (the terms of this arrangement are being managed by Johns Hopkins University and Northwestern University in accordance with their conflict-of-interest policies). M.W.J. has received research funding from F. Hoffmann-La Roche. S.K.M. has received consulting, advisory, or speaking honoraria from AstraZeneca, Amgen, GlaxoSmithKline, Novartis, and Sanofi/Regeneron. P.O.B. receives research funding from GlaxoSmithKline, AstraZeneca, Blueprint, and DBV Technologies; and serves on advisory boards for AstraZeneca, Sanofi, Genentech, and Kalvista. M.E.W. has received consulting, advisory, or speaking honoraria from Amgen, Areteia Therapeutics, AstraZeneca, Avalo Therapeutics, Boehringer Ingelheim, Celldex, Cellergy Pharma, Cerecor, Cytoreason, Eli Lilly, Equillium, Glaxosmithkline, Incyte, Kinaset, Merck, Novartis, Om Pharma, Overtone Therapeutics/Foresite Labs, Phylaxis, Pulmatrix, Rapt Therapeutics, Regeneron, Roche/Genentech, Sanofi/Genzyme, Sentien, Sound Biologics, Tetherex Pharmaceuticals, Teva, Upstream Bio, and Verona Pharma. The other authors have no conflicts of interest to disclose., (Published by Oxford University Press on behalf of Society for Leukocyte Biology 2024.)

Background: The immune response dynamics in COVID-19 patients remain a subject of intense investigation due to their implications for disease severity and treatment outcomes. We examined changes in leukocyte levels, eosinophil activity, and cytokine profiles in patients hospitalized with COVID-19., Methods: Serum samples were collected within the first 10 days of hospitalization/confirmed infection and analyzed for eosinophil granule proteins (EGP) and cytokines. Information from medical records including comorbidities, clinical symptoms, medications, and complete blood counts were collected at the time of admission, during hospitalization and at follow up approximately 3 months later., Results: Serum levels of eotaxin, type 1 and type 2 cytokines, and alarmin cytokines were elevated in COVID-19 patients, highlighting the heightened immune response ( p < 0.05). However, COVID-19 patients exhibited lower levels of eosinophils and eosinophil degranulation products compared to hospitalized controls ( p < 0.05). Leukocyte counts increased consistently from admission to follow-up, indicative of recovery., Conclusion: Attenuated eosinophil activity alongside elevated chemokine and cytokine levels during active infection, highlights the complex interplay of immune mediators in the pathogenesis COVID-19 and underscores the need for further investigation into immune biomarkers and treatment strategies.

Background: The demographic characteristics of patients with eosinophilic gastrointestinal diseases (EGIDs) are poorly understood. Population-based assessments of EGID demographics may indicate health disparities in diagnosis., Objectives: We aimed to characterize the demographic distribution of EGIDs and evaluate the potential for bias in reporting patient characteristics., Methods: We conducted a systematic review, extracting data on age, sex, gender, race, ethnicity, body mass index, insurance, and urban/rural residence on EGID patients and the source population. Differences in proportions were assessed by chi-square tests. Demographic reporting was compared to recent guidelines., Results: Among 50 studies that met inclusion/exclusion criteria, 12 reported ≥1 demographic feature in both EGID and source populations. Except for age and sex or gender, demographics were rarely described (race = 4, ethnicity = 1, insurance = 1) or were not described (body mass index, urban/rural residence). A higher proportion of male subjects was observed for EoE or esophageal eosinophilia relative to the source population, but no difference in gender or sex distribution was observed for other EGIDs. "Sex" and "gender" were used interchangeably, and frequently only the male proportion was reported. Reporting of race and ethnicity was inconsistent with guidelines., Conclusion: Current data support a male predominance for EoE only. Evidence was insufficient to support enrichment of EGIDs in any particular racial, ethnic, or other demographic group. Population-based studies presenting demographics on both cases and source populations are needed. Implementation of guidelines for more inclusive reporting of demographic characteristics is crucial to prevent disparities in timely diagnosis and management of patients with EGIDs., Competing Interests: Supported by U54AI117804 (Consortium of Eosinophilic Gastrointestinal Disease Researchers), which is part of the Rare Disease Clinical Research Network, an initiative of the Office of Rare Disease Research, National Center for Advancing Translational Sciences (NCATS), and is funded through collaboration between the National Institute of Allergy and Infectious Diseases (NIAID), the National Institute of Diabetes and Digestive and Kidney Diseases, NCATS, and patient advocacy groups including the American Partnership for Eosinophilic Disorders, Campaign Urging Research for Eosinophilic Disease (CURED), and Eosinophilic Family Coalition (EFC). This work was also funded in part by the Division of Intramural Research, NIAID, National Institutes of Health. Disclosure of potential conflict of interest: M. Chehade served as consultant for Regeneron, Allakos, Adare/Ellodi, Shire/Takeda, AstraZeneca, Sanofi, Bristol Myers Squibb, Phathom, Recludix Pharma, and Nexstone Immunology; and received research funding from Regeneron, Allakos, Shire/Takeda, AstraZeneca, Adare/Ellodi, Danone, and Bristol Myers Squibb. A. B. Muir has served on medical advisory board for Bristol Myers Squibb and Nexstone Immunology; and has received research funding from Morphic. M. H. Collins has received research funding from AstraZeneca, Ception, GSK, Meritage Pharma Inc, Receptos/Celgene/BMS, Regeneron Pharmaceuticals and Shire, a Takeda company; and is consultant for Allakos, Arena Pharmaceuticals, AstraZeneca, Calypso Biotech, EsoCap Biotech, GlaxoSmithKline, Receptos/Celgene/BMS, Regeneron Pharmaceuticals, Robarts Clinical Trials Inc/Alimentiv Inc and Shire, a Takeda company. C. M. Davis has received research funding from the National Institutes of Health/National Institute of Allergy and Infectious Disease (Consortium of Food Allergy Research/Consortium of Eosinophilic Gastrointestinal Researchers), DBV Technologies, DBV, Aimmune Therapeutics, Regeneron Pharmaceuticals, and Allergenis. G. T. Furuta is chief medical officer at EnteroTrack; consultant for Shire/Takeda; and has received grant funding from Arena and Holoclara. S. Gupta is consultant/data safety and monitoring board member or author for Adare, BMS, QOL, Takeda, MedScape, PVI, ViaSkin, and UpToDate; and has received research support from Allakos, Ellodi, and AstraZeneca. P. Khoury has received research funding from American Partnership for Eosinophilic Disorders. K. A. Peterson is consultant or served as advisor for AGA, Alladapt, AstraZeneca, Allakos, Bristol Meyers Squibb, Ellodi, Lucid, Nexstone, Peerview, Regeneron, Takeda, and WebMD; has received research support from AstraZeneca, Allakos, Adare, Regeneron-Sanofi, and Revolo; served as speaker for AGA, Regeneron, Peerview, Takeda, Allakos, and WebMD; received grant support (unrestricted) from Allakos and Chobani; and holds equity in Nexeos Bio. E. T. Jensen has received consultant fees from Regeneron, Jazz Pharmaceuticals, and TARGET-RWE. The rest of the authors declare that they have no relevant conflicts of interest., (© 2024 The Author(s).)

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., Competing Interests: Disclosure statement This study was funded by the Division of Intramural Research programs of the National Institute of Allergy and Immunology and the National Institute of Environmental Health Sciences (grant nos. ZIAES101074 and ZIAES101081), National Institutes of Health. Mepolizumab was provided by GlaxoSmithKline. Disclosure of potential conflict of interest: The authors declare that they have no relevant conflicts of interest., (Copyright © 2023. Published by Elsevier Inc.)

Although eosinophilic gastrointestinal diseases, including eosinophilic esophagitis, have been described over the past 2 to 3 decades, barriers to diagnosis and treatment are common and compounded by issues related to social determinants of health, race, ethnicity, and access to care. These barriers contribute to delays in diagnosis, resulting in persistent inflammation in the gastrointestinal tract, which can have significant consequences, including fibrostenotic complications in adults, failure to thrive in children, and decreased quality of life in all affected patients. In this commentary, we summarize gaps in knowledge regarding the epidemiology of eosinophilic gastrointestinal diseases, highlight barriers to diagnosis, discuss potential approaches based on best practices in other atopic and chronic gastrointestinal diseases, and provide recommendations for reducing barriers to timely diagnosis of eosinophilic gastrointestinal diseases in underserved populations., (Copyright © 2023 American Academy of Allergy, Asthma & Immunology. All rights reserved.)

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&#95;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&#95;EGID (inclusive of EGID+FA+FT, EGID+FT and ONLY&#95;EGID) when compared to HV. However, ALL&#95;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., (Published 2023. This article is a U.S. Government work and is in the public domain in the USA.)

Hypereosinophilic syndromes (HES) are a heterogeneous group of disorders defined by blood and/or tissue hypereosinophilia and clinical manifestations attributable to the eosinophilia. Although various clinical subtypes of HES have been described, the general approach to therapy in all subtypes has focused on the reduction of blood and tissue eosinophilia to improve symptoms and halt disease progression. Until recently, this typically involved the use of corticosteroids and/or other immunosuppressive or cytotoxic drugs with significant toxicity. Whereas imatinib, the first targeted therapy approved for treatment of HES, has dramatically changed the prognosis of patients with primary (myeloid) forms of HES, it is ineffective in patients with other HES subtypes. For these nonmyeloid patients with HES, the development of eosinophil-targeting biologics (most notably, mepolizumab, the first biologic approved for the treatment of HES) has been transformative. Nevertheless, important issues remain with respect to the efficacy and safety of these biologics in the treatment of the varied subtypes of HES. Moreover, with the increasing number of commercially available biologics with direct or indirect effects on eosinophils, questions related to the choice of initial biologic, potential reasons for biologic failure, and treatment options in the setting of incomplete response are becoming increasingly common., (Published by Elsevier Inc.)

Background: In eosinophilic gastrointestinal diseases, the role of eosinophils in disease pathogenesis and the effect of eosinophil depletion on patient outcomes are unclear. Benralizumab, an eosinophil-depleting monoclonal antibody that targets the interleukin-5 receptor α, might eliminate gastric tissue eosinophils and improve outcomes in eosinophilic gastritis. We aimed to assess the efficacy and safety of benralizumab in patients with eosinophilic gastritis., Methods: We conducted a single-site, randomised, double-blind, placebo-controlled, phase 2 trial at Cincinnati Children's Hospital Medical Center (Cincinnati, OH, USA). Individuals aged 12-60 years with symptomatic, histologically active eosinophilic gastritis (peak gastric eosinophil count ≥30 eosinophils per high-power field [eos/hpf] in at least five hpfs) and blood eosinophilia (>500 eosinophils per μL [eos/μL]) were randomly assigned (1:1, block size of four) to benralizumab 30 mg or placebo, stratified by the use of glucocorticoids for gastric disease. Investigators, study staff, and study participants were masked to treatment assignment; statisticians were unmasked when analysing data. Treatments were administered subcutaneously once every 4 weeks for a 12-week double-blind period (three total injections). The primary endpoint was the proportion of patients who achieved histological remission (peak gastric eosinophil count <30 eos/hpf) at week 12. Key secondary endpoints were the changes from baseline to week 12 in peak gastric eosinophil count, blood eosinophil count, eosinophilic gastritis histology (total, inflammatory, and structural feature scores), Eosinophilic Gastritis Endoscopic Reference System (EG-REFS) score, and patient-reported outcome symptom measures (Severity of Dyspepsia Assessment [SODA] and Patient-Reported Outcome Measurement Information System [PROMIS] short-form questionnaire). After the 12-week double-blind period, patients were eligible for entry into two open-label extension (OLE) periods up to week 88, in which all patients received benralizumab. Efficacy was analysed in the intention-to-treat (ITT) population and safety was assessed in all patients who received at least one dose of study drug. The trial was registered on ClinicalTrials.gov, NCT03473977, and is completed., Findings: Between April 23, 2018, and Jan 13, 2020, 34 patients were screened, and 26 were subsequently randomly assigned to benralizumab (n=13) or placebo (n=13) and included in the ITT and safety populations (mean age 19·5 years [SD 7·3]; 19 [73%] male patients and seven [27%] female patients). At week 12, ten (77% [95% CI 50 to 92]) of 13 patients who received benralizumab and one (8% [1 to 33]) of 13 who received placebo achieved histological remission (difference 69 percentage points [95% CI 32 to 85]; p=0·0010). Changes from baseline to week 12 were significantly greater in the benralizumab group versus the placebo group for peak gastric eosinophil counts (mean -137 eos/hpf [95% CI -186 to -88] vs -38 eos/hpf [-94 to 18]; p=0·0080), eosinophilic gastritis histology total score (mean -0·31 [-0·42 to -0·20] vs -0·02 [-0·16 to 0·12]; p=0·0016), histology inflammatory score (mean -0·46 [-0·60 to -0·31] vs -0·04 [-0·22 to 0·13]; p=0·0006), and blood eosinophil counts (median -1060 eos/μL [IQR -1740 to -830] vs -160 eos/μL [-710 to 120]; p=0·0044). Changes were not significantly different between the groups for eosinophilic gastritis histology structural score (mean -0·07 [95% CI -0·19 to 0·05] vs 0·03 [-0·09 to 0·15]; p=0·23), EG-REFS score (mean -1·0 [-2·3 to 0·3] vs -0·5 [-2·0 to 1·0]; p=0·62), or in patient-reported outcomes (SODA and PROMIS). During the double-blind period, treatment-emergent adverse events occurred in 11 (85%) of 13 patients in the benralizumab group and six (46%) of 13 in the placebo group; the most common treatment-emergent adverse events were headache (six [46%] vs two [15%] patients), nausea (three [23%] vs two [15%]), and vomiting (two [15%] vs three [23%]). There were no treatment-related deaths. Two patients had serious adverse events (dizziness and rhabdomyolysis in one patient; aspiration in one patient) during the OLE periods, which were considered unrelated to study treatment., Interpretation: Benralizumab treatment induced histological remission, as defined by absence of tissue eosinophilia, in most patients with eosinophilic gastritis. However, the persistence of histological, endoscopic, and other features of the disease suggest a co-existing, eosinophil-independent pathogenic mechanism and the need for broader targeting of type 2 immunity., Funding: AstraZeneca and the Division of Intramural Research (National Institute of Allergy and Infectious Diseases, US National Institutes of Health)., Competing Interests: Declaration of interests MHC has received research support from AstraZeneca, Regeneron, and LabCorp via payment to her institution; receives royalties from Revolo Biotherapeutics via payment to her institution; and has leadership roles in the American Partnership for Eosinophilic Disorders and the Campaign Urging Research for Eosinophilic Disease (CURED) Foundation. ADK serves on an advisory board for AstraZeneca. JPA has received research support from Cures Within Reach, Celgene, and Allakos; has received payment for lectures from Takeda; and serves on a data and safety monitoring board at OctaPharma USA. TS has received research support from the National Institute of Allergy and Infectious Diseases (US National Institutes of Health [NIH]) and Cincinnati Children's Hospital Medical Center through their Digestive Health Center and trustee award; and is co-inventor (along with MER) of a patent (US20200271668A1) for “Methods for diagnosing and treating eosinophilic gastritis.” LJM has received research support from AstraZeneca and NIH via payments to her institution. VAM has received consulting fees from Allakos, Regeneron, Sanofi, and Shire (a subsidiary of Takeda); has received honorarium for lectures from the American Gastroenterological Association; and serves on an adjudication board for Alladapt. VAK has received payment for lectures from Sanofi and Regeneron. CM-P has received research support from AstraZeneca via payment to her institution. KLK has received research support from AstraZeneca via payment to her institution. JTS has received consulting fees from a Takeda eosinophilic oesophagitis regional advisory board. ALD has received research support from the NIH via payments to her institution; and support from the American Academy of Allergy, Asthma and Immunology for meeting attendance. MER has received research support from AstraZeneca, Regeneron-Sanofi, GlaxoSmithKline, the CURED Foundation, the Food Allergy Fund, NIH grants, and a US–Israel Binational Grant (number 2019016); receives royalties from Ception Therapeutics (for reslizumab), Mapi Research Trust (for the Pediatric Eosinophilic Esophagitis Symptom Score version 2), and UpToDate; is a consultant for AstraZeneca, Bristol Myers Squibb, Regeneron-Sanofi, Revolo Biotherapeutics, Celldex, Nexstone One, and Guidepoint; has received payment for expert testimony from Tucker Ellis; and is an inventor on patents owned by Cincinnati Children's Hospital Medical Center; has a leadership role in the International Eosinophil Society; has equity interest in PulmOne Therapeutics, Spoon Guru, ClostraBio, Serpin Pharm, Celldex, Nextstone One, and Allakos; and has received equipment from Phadia. All other authors declare no competing interests., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

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., (© 2022 European Academy of Allergy and Clinical Immunology and John Wiley & Sons Ltd. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.)

Eosinophilia and eosinophil activation are recurrent features in various reactive states and certain hematologic malignancies. In patients with hypereosinophilia (HE), HE-induced organ damage is often encountered and may lead to the diagnosis of a hypereosinophilic syndrome (HES). A number of known mechanisms and etiologies contribute to the development of HE and HES. Based on these etiologies and the origin of eosinophils, HE and HES are divided into primary forms where eosinophils are clonal cells, reactive forms where an underlying reactive or neoplastic condition is detected and eosinophils are considered to be "non-clonal" cells, and idiopathic HE and HES in which neither a clonal nor a reactive underlying pathology is detected. Since 2012, this classification and the related criteria have been widely accepted and regarded as standard. However, during the past few years, new developments in the field and an increasing number of markers and targets have created a need to update these criteria and the classification of HE and HES. To address this challenge, a Working Conference on eosinophil disorders was organized in 2021. In this conference, a panel of experts representing the relevant fields, including allergy, dermatology, hematology, immunology, laboratory medicine, and pathology, met and discussed new markers and concepts as well as refinements in definitions, criteria and classifications of HE and HES. The outcomes of this conference are presented in this article and should assist in the diagnosis and management of patients with HE and HES in daily practice and in the preparation and conduct of clinical trials., (© 2022 The Authors. Allergy published by European Academy of Allergy and Clinical Immunology and John Wiley & Sons Ltd.)

Hypereosinophilic syndromes (HES) are a heterogenous group of rare disorders with clinical manifestations ranging from fatigue to life-threatening endomyocardial fibrosis and thromboembolic events. Given the broad differential diagnosis of HES, a comprehensive approach is needed to identify potential secondary (treatable) causes and define end-organ manifestations. Classification by clinical HES subtype is also useful in terms of assessing prognosis and guiding therapy. Corticosteroids remain the mainstay of initial therapy in the setting of acute, life-threatening PDGFR mutation-negative HES. Whereas the recent availability of eosinophil-targeted therapies with extraordinary efficacy and little apparent toxicity is changing the treatment paradigm, especially for idiopathic HES and overlap syndromes, questions remain unanswered regarding the choice of agent, impact of combination therapies, and long-term effects of eosinophil depletion. This review provides a case-based discussion of the differential diagnosis of HES, including the classification by clinical HES subtype. Treatment options are reviewed, including novel eosinophil-targeted agents recently approved for the treatment of HES and/or other eosinophil-associated disorders. Primary (myeloid) disorders associated with hypereosinophilia are not be addressed in depth in this review.

Lymphatic filariasis (LF) elimination activities started in Mali in 2005 in the most endemic areas and reached countrywide coverage in 2009. In 2004, the district of Bamako was endemic for LF with a prevalence of 1.5%. The current study was designed to determine LF endemicity level in the urban area of Bamako after three rounds of ivermectin and albendazole mass drug administration (MDA). A cross-sectional study was conducted in 2011 in Bamako city, consisting of human prevalence and entomological surveys. Volunteers aged 14 years and above were invited to participate and tested for evidence of Wuchereria bancrofti using night time blood thick smear microfilarial count and blood spots for LF antibodies using the SD BIOLINE Oncho/LF IgG4 Biplex rapid test (Ov16/Wb123). Mosquitoes were collected using CDC light and gravid traps and tested using molecular methods. Poolscreen software v2.0 was used to estimate vector transmission potential. Of the 899 volunteers, one (0.11%) was found to be positive for LF using the Oncho/LF IgG4 Biplex rapid test, and none was found to have Wuchereria bancrofti microfilariae. No mosquitoes were found infected among 6174 Culex spp. (85.2%), 16 Anopheles gambiae s.l. (An. gambiae s.l.) (0.2%), 26 Aedes spp. (0.4%), 858 Ceratopogonidae (11.8%) and 170 other insects not identified (2.3%) tested. Our data indicate that there was no active LF transmission in the low prevalence urban district of Bamako after three MDA rounds. These data helped the National LF programme move forward towards the elimination goal., (© 2022. The Author(s).)

Background: Transient increases in blood eosinophil counts have been observed in dupilumab clinical trials., Objective: To assess eosinophil counts and eosinophilia-related treatment-emergent adverse events (TEAEs) across 11 dupilumab clinical trials, comparing adult and adolescent patients with asthma and adult patients with chronic rhinosinusitis with nasal polyps (CRSwNP), atopic dermatitis, and eosinophilic esophagitis., Methods: Eosinophil counts, rates of eosinophilia-related TEAEs or treatment-emergent eosinophilia (>1,500 cells/μL), discontinuations, clinical symptoms, and efficacy in patients with asthma or CRSwNP with treatment-emergent eosinophilia are presented., Results: Transient increases in mean eosinophil counts were observed in dupilumab-treated patients with asthma (mean range across studies at baseline: 349-370 cells/μL; week 4: 515-578 cells/μL), CRSwNP (baseline: 440-448 cells/μL; week 16: 595 cells/μL), and atopic dermatitis (baseline: 434-600 cells/μL; week 4: 410-710 cells/μL), followed by a decline starting by week 24 to baseline or lower. No increases were seen in patients with eosinophilic esophagitis (baseline: 310 cells/μL; week 4: 230 cells/μL). In dupilumab-treated patients across all studies, rates of eosinophilia TEAEs were 0% to 13.6%. Clinical symptoms associated with increased eosinophils were rare (seven of 4,666 dupilumab-treated patients, including six cases of eosinophilic granulomatosis with polyangiitis) and occurred only in patients with asthma or CRSwNP. Eosinophilia was not associated with reduced dupilumab efficacy., Conclusions: Transient increases in eosinophil counts with dupilumab treatment did not affect efficacy and were rarely of clinical consequence. It remains important for physicians to base judgment on individual patient history and baseline eosinophil counts and to be alert to hypereosinophilic symptoms., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: Prospective genetic evaluation of patients at this referral research hospital presents clinical research challenges., Objectives: This study sought not only a single-gene explanation for participants' immune-related presentations, but viewed each participant holistically, with the potential to have multiple genetic contributions to their immune phenotype and other heritable comorbidities relevant to their presentation and health., Methods: This study developed a program integrating exome sequencing, chromosomal microarray, phenotyping, results return with genetic counseling, and reanalysis in 1505 individuals from 1000 families with suspected or known inborn errors of immunity., Results: Probands were 50.8% female, 71.5% were ≥18 years, and had diverse immune presentations. Overall, 327 of 1000 probands (32.7%) received 361 molecular diagnoses. These included 17 probands with diagnostic copy number variants, 32 probands with secondary findings, and 31 probands with multiple molecular diagnoses. Reanalysis added 22 molecular diagnoses, predominantly due to new disease-gene associations (9 of 22, 40.9%). One-quarter of the molecular diagnoses (92 of 361) did not involve immune-associated genes. Molecular diagnosis was correlated with younger age, male sex, and a higher number of organ systems involved. This program also facilitated the discovery of new gene-disease associations such as SASH3-related immunodeficiency. A review of treatment options and ClinGen actionability curations suggest that at least 251 of 361 of these molecular diagnoses (69.5%) could translate into ≥1 management option., Conclusions: This program contributes to our understanding of the diagnostic and clinical utility whole exome analysis on a large scale., (Published by Elsevier Inc.)

Our understanding of eosinophil biology, development, and regulation has dramatically increased in the past decade, leading to new paradigms for the role of eosinophils in human health and disease and, perhaps more importantly, providing insights toward novel treatment strategies in the fight against eosinophil-mediated inflammation. In this review, we discuss recent advances regarding the role of eosinophils in host-viral defense, eosinophil heterogeneity, and eosinophil-targeted therapies., Competing Interests: The authors declare that they have no competing interests.No competing interests were disclosed.No competing interests were disclosed., (Copyright: © 2022 Klion AD et al.)

The SD Bioline® IgG4 rapid diagnostic test (RDT) detects IgG4 antibodies induced by the Onchocerca volvulus-specific antigen Ov16. We evaluated the stability of the RDT results over 1 month, at different time points after completion of each assay, using eluted dried blood spots collected in central Cameroon. Agreement coefficients regarding positivity between 30 minutes and 24 hours, 1, 2, 3, and 4 weeks were, 96.4%, 93.4%, 93.3%, 93.2%, and 93.2%, respectively. Between 30 minutes and 24 hours, 3.6% of the 15,444 tests showed inconsistent results with 81.2% of these tests changing from negative to positive, increasing O. volvulus antibody prevalence from 23.9% to 26.2% (P < 0.0001). This change from negative to positive outcome was confirmed at the subsequent timepoints. Depending on the desired accuracy of prevalence estimates, reading time may have to be redefined more strictly.

Influx of eosinophils into the lungs is typically associated with type II responses during allergy and fungal and parasitic infections. However, we previously reported that eosinophils accumulate in lung lesions during type I inflammatory responses to Mycobacterium tuberculosis (Mtb) in humans, macaques, and mice, in which they support host resistance. Here we show eosinophils migrate into the lungs of macaques and mice as early as one week after Mtb exposure. In mice this influx is CCR3 independent and instead requires cell-intrinsic expression of the oxysterol receptor GPR183, which is highly expressed on human and macaque eosinophils. Murine eosinophils interact directly with bacilli-laden alveolar macrophages, which upregulate the oxysterol-synthesizing enzyme Ch25h, and eosinophil recruitment is impaired in Ch25h-deficient mice. Our findings show that eosinophils are among the earliest cells from circulation to sense and respond to Mtb infection of alveolar macrophages and reveal a role for GPR183 in the migration of eosinophils into lung tissue., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: Previous studies of targeted eosinophil biologics in eosinophilic esophagitis have yielded mixed results. Possible explanations include incomplete eosinophil depletion with anticytokine (anti-IL-5) treatments and/or irreversible fibrotic tissue changes contributing to symptomatology., Objective: To characterize the therapeutic effect of eosinophil depletion in patients with hypereosinophilic syndrome with varied eosinophilic gastrointestinal (GI) disorders., Methods: Hematologic, histologic, endoscopic, and clinical symptoms for a subset (n = 7) of hypereosinophilic syndrome patients with GI tissue eosinophilia enrolled in a phase 2 clinical trial of benralizumab (anti-IL-5RA) were assessed before and after treatment (NCT02130882)., Results: Blood and GI tissue eosinophils were completely depleted in all segments of the GI tract, and all patients reported improved GI symptoms, in some cases as early as after the first monthly dose. Some patients had recurrent symptomatic flares without recurrent peripheral or tissue eosinophilia, in most cases after prolonged symptomatic remission and in the setting of liberalization of dietary restrictions and/or tapering of background therapy. Although eosinophil-associated histologic changes improved in all segments, epithelial changes persisted in the esophagus and stomach in patients with recurrent disease flares even after 1 year of treatment. Serum tryptase and GI mast cells were generally unchanged with treatment, and increases were not associated with disease flares. Serum levels of IL-4 and IL-5 increased with benralizumab treatment (both P < .05)., Conclusions: Benralizumab treatment completely depleted blood and GI tissue eosinophilia in patients with eosinophilic GI disorders, but clinical response, while encouraging, was heterogeneous. Residual symptoms in some patients may reflect persistent epithelial changes in the upper GI tract., (Copyright © 2022 American Academy of Allergy, Asthma & Immunology. All rights reserved.)

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/mm 3 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., (Copyright © 2022 American Academy of Allergy, Asthma & Immunology. All rights reserved.)

There is a need for better tools to monitor the transmission of lymphatic filariasis and malaria in areas undergoing interventions to interrupt transmission. Therefore, mosquito collection methods other than human landing catch (HLC) are needed. This study aimed to compare the Ifakara tent trap type C (ITTC) and the Biogents sentinel trap (BGST) to the HLC in areas with different vector densities. Mosquitoes were collected in two villages in Mali from July to December in 2011 and 2012. The three methods were implemented at each site with one ITTC, one BGST, and one HLC unit that consisted of one room with two collectors-one indoor and the other outdoor. The Anopheles collected in 2011 were individually dissected, whereas those from 2012 were screened in pools using reverse transcription-polymerase chain reaction (RT-PCR) to determine the maximum infection prevalence likelihood (MIPL) for Wuchereria bancrofti and Plasmodium falciparum. The dissection of the females also allowed to assess the parity rates, as well its results. Over the 2 years, the HLC method collected 1,019 Anopheles, yields that were 34- and 1.5-fold higher than those with the BGST and ITTC, respectively. None of the dissected Anopheles were infected. The RT-PCR results showed comparable MIPL between HLC and ITTC for W. bancrofti with one infected pool from each trap's yield (respectively 0.03% [0.0009-0.2%] and 0.04% [0.001-0.2%]). For P. falciparum, no infected pool was recovered from BGST. The ITTC is a good alternative to HLC for xenomonitoring of program activities.

Background: Diethylcarbamazine citrate (DEC) treatment of loiasis is complicated by adverse reactions that are correlated with the number of circulating microfilariae (mf). The cause of these reactions is unknown, but they are accompanied by a dramatic interleukin-5 (IL-5)-dependent increase in eosinophilia and evidence of eosinophil activation., Methods: To explore the role of IL-5 driven eosinophilia in post-DEC reactions, 8 adults with confirmed loiasis and <5000 mf/mL blood were enrolled in a randomized, double-blind, placebo-controlled trial of the humanized anti-IL-5 antibody, reslizumab, (1.0 mg/kg IV) administered 3 to 7 days prior to initiation of DEC treatment (9 mg/kg/day for 21 days). The primary endpoint was the reduction in absolute eosinophil count (AEC) during the first week of DEC treatment., Results: Baseline characteristics were comparable between the two groups. Single dose reslizumab lowered the AEC by 77% prior to initiation of DEC therapy (vs. 12% in the placebo group, P < .05). More importantly, AEC remained below baseline in the first week of DEC treatment in all subjects who received reslizumab and in none of the placebo subjects. Mf clearance occurred within 2 days of initiation of DEC in all 7 mf-positive subjects. Mild to moderate adverse events were seen in all 8 subjects and were not significantly different between the groups., Conclusions: In summary, although reslizumab was able to blunt peripheral eosinophilia post-DEC treatment in subjects with loiasis and had no effect on microfilarial clearance, the reduction in AEC appeared to have been insufficient to prevent post-treatment AEs., (Published by Oxford University Press for the Infectious Diseases Society of America 2020.)

Host resistance to Mycobacterium tuberculosis (Mtb) infection requires the activities of multiple leukocyte subsets, yet the roles of the different innate effector cells during tuberculosis are incompletely understood. Here we uncover an unexpected association between eosinophils and Mtb infection. In humans, eosinophils are decreased in the blood but enriched in resected human tuberculosis lung lesions and autopsy granulomas. An influx of eosinophils is also evident in infected zebrafish, mice, and nonhuman primate granulomas, where they are functionally activated and degranulate. Importantly, using complementary genetic models of eosinophil deficiency, we demonstrate that in mice, eosinophils are required for optimal pulmonary bacterial control and host survival after Mtb infection. Collectively, our findings uncover an unexpected recruitment of eosinophils to the infected lung tissue and a protective role for these cells in the control of Mtb infection in mice., Competing Interests: Disclosures:   D.M. Lowe reported personal fees from Merck, non-financial support from CSL Behring, and non-financial support from Fujifilm Chemical Co. outside the submitted work. No other disclosures were reported., (© 2021 Bohrer et al.)

Hypereosinophilic syndromes (HES) comprises a group of rare disorders characterized by blood hypereosinophilia (>1.5 × 10 9 /l) accompanied by eosinophil-associated organ damage. The 2016 World Health Organization classification recognizes a category of myeloid/lymphoid neoplasms with prominent eosinophilia (M/L eo ) and well-characterized gene rearrangements of PDGFRA/B, FGFR1 or JAK2. PDGFRA/B-rearranged patients usually manifest as imatinib-sensitive myeloproliferative neoplasms (MPNs). FGFR1- and JAK2- rearranged cases may manifest as MPNs or aggressive lymphomas/leukemias and historically have had a dismal prognosis, although clinical trials with targeted treatment are promising. A negative screen for M/L eo in a patient with myeloid features should prompt consideration of a diagnosis of chronic eosinophilic leukemia-not otherwise specified. If these are excluded and a secondary cause is not identified, a diagnosis of idiopathic HES and/or other rare variants of HES should be considered. This review, through an illustrative case, summarizes current knowledge on HES pointing at new directions in diagnosis and treatment., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Background: Mass drug administration (MDA) with ivermectin is the main strategy for onchocerciasis elimination. Ivermectin is generally safe, but is associated with serious adverse events in individuals with high Loa loa microfilarial densities (MFD). Therefore, ivermectin MDA is not recommended in areas where onchocerciasis is hypo-endemic and L loa is co-endemic. To eliminate onchocerciasis in those areas, a test-and-not-treat (TaNT) strategy has been proposed. We investigated whether onchocerciasis elimination can be achieved using TaNT and the required duration., Methods: We used the individual-based model ONCHOSIM to predict the impact of TaNT on onchocerciasis microfilarial (mf) prevalence. We simulated precontrol mf prevalence levels from 2% to 40%. The impact of TaNT was simulated under varying levels of participation, systematic nonparticipation, and exclusion from ivermectin resulting from high L loa MFD. For each scenario, we assessed the time to elimination, defined as bringing onchocerciasis mf prevalence below 1.4%., Results: In areas with 30% to 40% precontrol mf prevalence, the model predicted that it would take between 14 and 16 years to bring the mf prevalence below 1.4% using conventional MDA, assuming 65% participation. TaNT would increase the time to elimination by up to 1.5 years, depending on the level of systematic nonparticipation and the exclusion rate. At lower exclusion rates (≤2.5%), the delay would be less than 6 months., Conclusions: Our model predicts that onchocerciasis can be eliminated using TaNT in L loa co-endemic areas. The required treatment duration using TaNT would be only slightly longer than in areas with conventional MDA, provided that participation is good., (© The Author(s) 2020. Published by Oxford University Press for the Infectious Diseases Society of America.)

Since the earliest descriptions of this enigmatic cell, eosinophils have been implicated in both protective and pathogenic immune responses to helminth infection. Nevertheless, despite substantial data from in vitro studies, human infections, and animal models, their precise role in helminth infection remains incompletely understood. This is due to a number of factors, including the heterogeneity of the many parasites included in the designation "helminth," the complexity and redundancy in the host immune response to helminths, and the pleiotropic functions of eosinophils themselves. This review examines the consequences of helminth-associated eosinophilia in the context of protective immunity, pathogenesis, and immunoregulation.