{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,2]],"date-time":"2026-06-02T06:17:37Z","timestamp":1780381057107,"version":"3.54.1"},"reference-count":51,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2025,9,19]],"date-time":"2025-09-19T00:00:00Z","timestamp":1758240000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100000002","name":"National Institutes of Health","doi-asserted-by":"publisher","award":["HL147898, 2UL1TR001425, DK078392, HL172649"],"award-info":[{"award-number":["HL147898, 2UL1TR001425, DK078392, HL172649"]}],"id":[{"id":"10.13039\/100000002","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Immunol."],"abstract":"<jats:sec><jats:title>Background<\/jats:title><jats:p>Cardiac complications in patients with hypereosinophilia cause significant morbidity and mortality. However, mechanisms of how eosinophilic inflammation causes heart damage are poorly understood.<\/jats:p><\/jats:sec><jats:sec><jats:title>Methods<\/jats:title><jats:p>We developed a model of hypereosinophilia-associated heart disease by challenging hypereosinophilic mice with a peptide from the cardiac myosin heavy chain. Disease outcomes were measured by histology, immunohistochemistry, flow cytometry, and measurement of cells and biomarkers in peripheral blood. Eosinophil dependence was determined by using eosinophil-deficient mice (\u0394dblGATA). Single cells from the heart were subjected to single-cell RNA sequencing to assess cell composition, activation states, and expression profiles. <jats:italic>In vitro<\/jats:italic> studies used bone marrow-derived eosinophils (BMDeos) and stimulated them with cytokines and pathogen-associated molecular patterns, followed by assessment of activation markers by flow cytometry.<\/jats:p><\/jats:sec><jats:sec><jats:title>Results<\/jats:title><jats:p>Mice challenged with the myocarditic and control peptide had peripheral blood leukocytosis, but only those challenged with the myocarditic peptide had heart inflammation. Heart tissue was infiltrated by eosinophil-rich inflammatory infiltrates associated with cardiomyocyte damage. Disease penetrance and severity were decreased in eosinophil-deficient mice. Single-cell RNA sequencing showed the enrichment of myeloid cells, T cells, and granulocytes (neutrophils and eosinophils) in myocarditic mice. Focusing on eosinophils, there was increased expression of genes associated with type 1 cell activation (such as CD274\/PDL1), complement activation, and pathogen-associated molecular pattern recognition. To verify findings generated by single-cell RNA sequencing on a protein level, we performed flow cytometry analysis and assessed the level of type 1 and type 2 biomarkers CD274 and CD101, respectively. The proportion of cells expressing surface CD274 increased on both neutrophils and eosinophils, particularly in mice that showed inflammation by histology. There was no significant increase in expression of CD101. Finally, we assessed whether activation markers can be induced on eosinophils <jats:italic>in vitro<\/jats:italic>. Interferon \u03b3 (IFN\u03b3) markedly increased expression of CD274, consistent with type 1 polarization. Furthermore, BMDeos stimulated with LPS showed a concentration-dependent increase in the level of CD274 expression.<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusion<\/jats:title><jats:p>Eosinophils are required for heart damage in hypereosinophilia-associated heart disease. Heart-infiltrating eosinophils in an inflammatory condition show type 1 activation, which can be recapitulated <jats:italic>in vitro<\/jats:italic>.<\/jats:p><\/jats:sec>","DOI":"10.3389\/fimmu.2025.1635483","type":"journal-article","created":{"date-parts":[[2025,9,19]],"date-time":"2025-09-19T05:28:32Z","timestamp":1758259712000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":2,"title":["The role of eosinophils and their activation state in hypereosinophilia-associated heart disease"],"prefix":"10.3389","volume":"16","author":[{"given":"Usman","family":"Sunusi","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Immaculeta","family":"Osuji","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Benjamin","family":"Ziegelmeyer","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mario","family":"Medvedovic","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Haley","family":"Todd","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Joe","family":"Abou-Khalil","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Nives","family":"Zimmermann","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1965","published-online":{"date-parts":[[2025,9,19]]},"reference":[{"key":"B1","doi-asserted-by":"publisher","first-page":"85","DOI":"10.1007\/s00428-022-03402-8","article-title":"Updates on eosinophilic disorders","volume":"482","author":"Tzankov","year":"2023","journal-title":"Virchows Arch"},{"key":"B2","doi-asserted-by":"publisher","first-page":"1319","DOI":"10.1016\/j.jaci.2009.09.022","article-title":"Hypereosinophilic syndrome: a multicenter, retrospective analysis of clinical characteristics and response to therapy","volume":"124","author":"Ogbogu","year":"2009","journal-title":"J Allergy Clin Immunol"},{"key":"B3","doi-asserted-by":"publisher","DOI":"10.1016\/j.iac.2007.07.001","article-title":"Cardiovascular manifestations of hypereosinophilic syndromes","volume":"27","author":"Ogbogu","year":"2007","journal-title":"Immunol Allergy Clin North Am"},{"key":"B4","doi-asserted-by":"publisher","DOI":"10.1182\/blood.V83.10.2759.2759","article-title":"The idiopathic hypereosinophilic syndrome","volume":"83","author":"Weller","year":"1994","journal-title":"Blood"},{"key":"B5","doi-asserted-by":"publisher","DOI":"10.1016\/0046-8177(89)90096-8","article-title":"Eosinophilic products lead to myocardial damage","volume":"20","author":"Sasano","year":"1989","journal-title":"Hum Pathol"},{"key":"B6","doi-asserted-by":"publisher","DOI":"10.1016\/0002-9343(79)90227-4","article-title":"The cardiovascular manifestations of the hypereosinophilic syndrome. Prospective study of 26 patients, with review of the literature","volume":"67","author":"Parrillo","year":"1979","journal-title":"Am J Med"},{"key":"B7","doi-asserted-by":"publisher","DOI":"10.1016\/j.amjms.2017.04.002","article-title":"Eosinophilic myocarditis","volume":"354","author":"Cheung","year":"2017","journal-title":"Am J Med Sci"},{"key":"B8","doi-asserted-by":"publisher","DOI":"10.1016\/j.jaci.2012.07.024","article-title":"Workshop report from the national institutes of health taskforce on the research needs of eosinophil-associated diseases (TREAD)","volume":"130","author":"Bochner","year":"2012","journal-title":"J Allergy Clin Immunol"},{"key":"B9","doi-asserted-by":"publisher","first-page":"69","DOI":"10.1002\/JLB.5MR0118-028R","article-title":"Revisiting the NIH taskforce on the research needs of eosinophil-associated diseases (RE-TREAD)","volume":"104","author":"Khoury","year":"2018","journal-title":"J Leukoc Biol"},{"key":"B10","doi-asserted-by":"publisher","DOI":"10.1152\/ajpheart.00133.2019","article-title":"Characterization of a mouse model of hypereosinophilia-associated heart disease","volume":"317","author":"Prows","year":"2019","journal-title":"Am J Physiol Heart Circ Physiol"},{"key":"B11","doi-asserted-by":"publisher","DOI":"10.1186\/s12864-019-6108-0","article-title":"Heart disease in a mutant mouse model of spontaneous eosinophilic myocarditis maps to three loci","volume":"20","author":"Zimmermann","year":"2019","journal-title":"BMC Genomics"},{"key":"B12","doi-asserted-by":"publisher","DOI":"10.1084\/jem.20161702","article-title":"Eosinophil-derived IL-4 drives progression of myocarditis to inflammatory dilated cardiomyopathy","volume":"214","author":"Diny","year":"2017","journal-title":"J Exp Med"},{"key":"B13","doi-asserted-by":"publisher","DOI":"10.1126\/science.ade4177","article-title":"Neuromedin U programs eosinophils to promote mucosal immunity of the small intestine","volume":"381","author":"Li","year":"2023","journal-title":"Science"},{"key":"B14","doi-asserted-by":"publisher","DOI":"10.1038\/s41586-022-05628-7","article-title":"Active eosinophils regulate host defence and immune responses in colitis","volume":"615","author":"Gurtner","year":"2023","journal-title":"Nature"},{"key":"B15","doi-asserted-by":"publisher","DOI":"10.1084\/jem.172.5.1425","article-title":"Eosinophilia in transgenic mice expressing interleukin 5","volume":"172","author":"Dent","year":"1990","journal-title":"J Exp Med"},{"key":"B16","doi-asserted-by":"publisher","DOI":"10.1084\/jem.20020656","article-title":"Targeted deletion of a high-affinity GATA-binding site in the GATA-1 promoter leads to selective loss of the eosinophil lineage","volume":"195","author":"Yu","year":"2002","journal-title":"vivo J Exp Med"},{"key":"B17","doi-asserted-by":"publisher","DOI":"10.1172\/JCI118642","article-title":"Identification of cardiac myosin peptides capable of inducing autoimmune myocarditis in BALB\/c mice","volume":"97","author":"Pummerer","year":"1996","journal-title":"J Clin Invest"},{"key":"B18","doi-asserted-by":"publisher","DOI":"10.1385\/1-59259-805-6:175","article-title":"Animal models for autoimmune myocarditis and autoimmune thyroiditis","volume":"102","author":"Cihakova","year":"2004","journal-title":"Methods Mol Med"},{"key":"B19","doi-asserted-by":"publisher","first-page":"199","DOI":"10.1007\/978-1-0716-2364-0_14","article-title":"Detection of eosinophils in tissue sections by immunohistochemistry","volume":"2506","author":"Zhu","year":"2022","journal-title":"Methods Mol Biol"},{"key":"B20","doi-asserted-by":"publisher","first-page":"329","DOI":"10.1016\/j.cels.2019.03.003","article-title":"DoubletFinder: doublet detection in single-cell RNA sequencing data using artificial nearest neighbors","volume":"8","author":"McGinnis","year":"2019","journal-title":"Cell Syst"},{"key":"B21","doi-asserted-by":"publisher","first-page":"296","DOI":"10.1186\/s13059-019-1874-1","article-title":"Normalization and variance stabilization of single-cell RNA-seq data using regularized negative binomial regression","volume":"20","author":"Hafemeister","year":"2019","journal-title":"Genome Biol"},{"key":"B22","doi-asserted-by":"publisher","DOI":"10.1038\/nbt.4096","article-title":"Integrating single-cell transcriptomic data across different conditions, technologies, and species","volume":"36","author":"Butler","year":"2018","journal-title":"Nat Biotechnol"},{"key":"B23","doi-asserted-by":"publisher","first-page":"1888","DOI":"10.1016\/j.cell.2019.05.031","article-title":"Comprehensive integration of single-cell data","volume":"177","author":"Stuart","year":"2019","journal-title":"Cell"},{"key":"B24","doi-asserted-by":"publisher","DOI":"10.1038\/s41590-018-0276-y","article-title":"Reference-based analysis of lung single-cell sequencing reveals a transitional profibrotic macrophage","volume":"20","author":"Aran","year":"2019","journal-title":"Nat Immunol"},{"key":"B25","doi-asserted-by":"publisher","DOI":"10.1038\/ni1008-1091","article-title":"The Immunological Genome Project: networks of gene expression in immune cells","volume":"9","author":"Heng","year":"2008","journal-title":"Nat Immunol"},{"key":"B26","doi-asserted-by":"publisher","DOI":"10.1089\/omi.2011.0118","article-title":"clusterProfiler: an R package for comparing biological themes among gene clusters","volume":"16","author":"Yu","year":"2012","journal-title":"OMICS"},{"key":"B27","doi-asserted-by":"publisher","DOI":"10.4049\/jimmunol.181.6.4004","article-title":"Functionally competent eosinophils differentiated ex vivo in high purity from normal mouse bone marrow","volume":"181","author":"Dyer","year":"2008","journal-title":"J Immunol"},{"key":"B28","doi-asserted-by":"publisher","DOI":"10.3389\/fimmu.2022.1041660","article-title":"Differential regulation of Type 1 and Type 2 mouse eosinophil activation by apoptotic cells","volume":"13","author":"Dolitzky","year":"2022","journal-title":"Front Immunol"},{"key":"B29","doi-asserted-by":"publisher","DOI":"10.1371\/journal.pone.0072249","article-title":"IFN-gamma-stimulated neutrophils suppress lymphocyte proliferation through expression of PD-L1","volume":"8","author":"de Kleijn","year":"2013","journal-title":"PloS One"},{"key":"B30","doi-asserted-by":"publisher","first-page":"115072","DOI":"10.1016\/j.celrep.2024.115072","article-title":"Pathogenic role for CD101-negative neutrophils in the type I interferon-mediated immunopathogenesis of tuberculosis","volume":"44","author":"Saqib","year":"2025","journal-title":"Cell Rep"},{"key":"B31","doi-asserted-by":"publisher","first-page":"73","DOI":"10.1159\/000068371","article-title":"Immunologic interaction between infiltrating eosinophils and T lymphocytes in murine spontaneous eosinophilic myocarditis","volume":"130","author":"Hirasawa","year":"2003","journal-title":"Int Arch Allergy Immunol"},{"key":"B32","doi-asserted-by":"publisher","first-page":"107990","DOI":"10.1016\/j.isci.2023.107990","article-title":"Hypereosinophilia causes progressive cardiac pathologies in mice","volume":"26","author":"Diny","year":"2023","journal-title":"iScience"},{"key":"B33","doi-asserted-by":"publisher","DOI":"10.1016\/j.ajpath.2014.11.023","article-title":"Natural killer cells limit cardiac inflammation and fibrosis by halting eosinophil infiltration","volume":"185","author":"Ong","year":"2015","journal-title":"Am J Pathol"},{"key":"B34","doi-asserted-by":"publisher","DOI":"10.1007\/s004280050192","article-title":"Spontaneous myocarditis in DBA\/2 mice. Light microscopic study with transmission and X-ray analytical electron microscopic studies","volume":"432","author":"Hirasawa","year":"1998","journal-title":"Virchows Arch"},{"key":"B35","doi-asserted-by":"publisher","DOI":"10.4049\/jimmunol.158.3.1332","article-title":"Expression of IL-5 in thymocytes\/T cells leads to the development of a massive eosinophilia, extramedullary eosinophilopoiesis, and unique histopathologies","volume":"158","author":"Lee","year":"1997","journal-title":"J Immunol"},{"key":"B36","doi-asserted-by":"publisher","DOI":"10.1146\/annurev.immunol.24.021605.090720","article-title":"The eosinophil","volume":"24","author":"Rothenberg","year":"2006","journal-title":"Annu Rev Immunol"},{"key":"B37","doi-asserted-by":"publisher","DOI":"10.1111\/all.15751","article-title":"Eosinophils from A to Z","volume":"78","author":"Gigon","year":"2023","journal-title":"Allergy"},{"key":"B38","doi-asserted-by":"publisher","DOI":"10.1182\/blood.V51.3.457.457","article-title":"Human eosinophils. Purification and cytotoxic capability of eosinophils from patients with the hypereosinophilic syndrome","volume":"51","author":"Parrillo","year":"1978","journal-title":"Blood"},{"key":"B39","doi-asserted-by":"publisher","DOI":"10.1161\/01.CIR.81.3.1081","article-title":"Eosinophils from hypereosinophilic patients damage endocardium of isolated feline heart muscle preparations","volume":"81","author":"Shah","year":"1990","journal-title":"Circulation"},{"key":"B40","doi-asserted-by":"publisher","first-page":"6396","DOI":"10.1038\/s41467-020-19297-5","article-title":"Eosinophils improve cardiac function after myocardial infarction","volume":"11","author":"Liu","year":"2020","journal-title":"Nat Commun"},{"key":"B41","doi-asserted-by":"publisher","DOI":"10.1093\/cvr\/cvab237","article-title":"Interleukin-5-induced eosinophil population improves cardiac function after myocardial infarction","volume":"118","author":"Xu","year":"2022","journal-title":"Cardiovasc Res"},{"key":"B42","doi-asserted-by":"publisher","first-page":"195","DOI":"10.1093\/cvr\/cvac060","article-title":"Eosinophils protect pressure overload- and beta-adrenoreceptor agonist-induced cardiac hypertrophy","volume":"119","author":"Yang","year":"2023","journal-title":"Cardiovasc Res"},{"key":"B43","doi-asserted-by":"publisher","DOI":"10.1093\/eurheartj\/ehad262","article-title":"Cationic proteins from eosinophils bind bone morphogenetic protein receptors promoting vascular calcification and atherogenesis","volume":"44","author":"Meng","year":"2023","journal-title":"Eur Heart J"},{"key":"B44","doi-asserted-by":"publisher","DOI":"10.1126\/sciimmunol.abi5586","article-title":"Clonally expanded, GPR15-expressing pathogenic effector T(H)2 cells are associated with eosinophilic esophagitis","volume":"6","author":"Morgan","year":"2021","journal-title":"Sci Immunol"},{"key":"B45","doi-asserted-by":"publisher","DOI":"10.1172\/JCI85664","article-title":"Lung-resident eosinophils represent a distinct regulatory eosinophil subset","volume":"126","author":"Mesnil","year":"2016","journal-title":"J Clin Invest"},{"key":"B46","doi-asserted-by":"publisher","DOI":"10.1111\/all.15180","article-title":"Upparahalli Venkateshaiah S. Role of IL-18-transformed CD274-expressing eosinophils in promoting airway obstruction in experimental asthma","volume":"77","author":"Mishra","year":"2022","journal-title":"Allergy"},{"key":"B47","doi-asserted-by":"publisher","first-page":"8085615","DOI":"10.1155\/2020\/8085615","article-title":"Elevated levels of activated and pathogenic eosinophils characterize moderate-severe house dust mite allergic rhinitis","volume":"2020","author":"Chen","year":"2020","journal-title":"J Immunol Res"},{"key":"B48","doi-asserted-by":"publisher","DOI":"10.3389\/fphar.2022.835510","article-title":"PD-1\/PD-L1 inhibitor-associated myocarditis: epidemiology, characteristics, diagnosis, treatment, and potential mechanism","volume":"13","author":"Dong","year":"2022","journal-title":"Front Pharmacol"},{"key":"B49","doi-asserted-by":"publisher","DOI":"10.1161\/CIRCULATIONAHA.107.709360","article-title":"Endothelial programmed death-1 ligand 1 (PD-L1) regulates CD8+ T-cell mediated injury in the heart","volume":"116","author":"Grabie","year":"2007","journal-title":"Circulation"},{"key":"B50","doi-asserted-by":"publisher","DOI":"10.1016\/j.jacbts.2022.05.006","article-title":"The programmed death-1 signaling axis modulates inflammation and LV structure\/function in a stress-induced cardiomyopathy model","volume":"7","author":"Hayashi","year":"2022","journal-title":"JACC Basic Transl Sci"},{"key":"B51","doi-asserted-by":"publisher","first-page":"389","DOI":"10.1038\/s44161-024-00447-7","article-title":"The PD-1-PD-L1 pathway maintains an immunosuppressive environment essential for neonatal heart regeneration","volume":"3","author":"Vargas Aguilar","year":"2024","journal-title":"Nat Cardiovasc Res"}],"container-title":["Frontiers in Immunology"],"original-title":[],"link":[{"URL":"https:\/\/www.frontiersin.org\/articles\/10.3389\/fimmu.2025.1635483\/full","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,9,19]],"date-time":"2025-09-19T05:28:33Z","timestamp":1758259713000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.frontiersin.org\/articles\/10.3389\/fimmu.2025.1635483\/full"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025,9,19]]},"references-count":51,"alternative-id":["10.3389\/fimmu.2025.1635483"],"URL":"https:\/\/doi.org\/10.3389\/fimmu.2025.1635483","relation":{},"ISSN":["1664-3224"],"issn-type":[{"value":"1664-3224","type":"electronic"}],"subject":[],"published":{"date-parts":[[2025,9,19]]},"article-number":"1635483"}}