title: Exosome secretion by eosinophils: A possible role in asthma pathogenesis.
abstract: BACKGROUND
  Eosinophils secrete several granules that are involved in the propagation of inflammatory responses in patients with pathologies such as asthma.
  
  
  OBJECTIVE
  We hypothesized that some of these granules are exosomes, which, when transferred to the recipient cells, could modulate asthma progression.
  
  
  METHODS
  Eosinophils were purified from peripheral blood and cultured with or without IFN-γ or eotaxin. Multivesicular bodies (MVBs) in eosinophils were studied by using fluorescence microscopy, transmission electron microscopy (TEM), and flow cytometry. Exosome secretion was measured and exosome characterization was performed with TEM, Western blotting, and NanoSight analysis.
  
  
  RESULTS
  Generation of MVBs in eosinophils was confirmed by using fluorescence microscopy and flow cytometry and corroborated by means of TEM. Having established that eosinophils contain MVBs, our aim was to demonstrate that eosinophils secrete exosomes. To do this, we purified exosomes from culture medium of eosinophils and characterized them. Using Western blot analysis, we demonstrated that eosinophils secreted exosomes and that the discharge of exosomes to extracellular media increases after IFN-γ stimulation. We measured exosome size and quantified exosome production from healthy and asthmatic subjects using nanotracking analysis. We found that exosome production was augmented in asthmatic patients.
  
  
  CONCLUSIONS
  Our findings are the first to demonstrate that eosinophils contain functional MVBs and secrete exosomes and that their secretion is increased in asthmatic patients. Thus exosomes might play an important role in the progression of asthma and eventually be considered a biomarker.
authors.affiliation: Department of Immunology, IIS-Fundación Jiménez Díaz, Madrid, Spain; CIBER de Enfermedades Respiratorias (CIBERES), Madrid, Spain.
authors.forename: Carla
authors.initials: C
authors.lastname: Mazzeo
authors.affiliation: Department of Immunology, IIS-Fundación Jiménez Díaz, Madrid, Spain; CIBER de Enfermedades Respiratorias (CIBERES), Madrid, Spain.
authors.forename: José Antonio
authors.initials: JA
authors.lastname: Cañas
authors.affiliation: Department of Immunology, IIS-Fundación Jiménez Díaz, Madrid, Spain; CIBER de Enfermedades Respiratorias (CIBERES), Madrid, Spain.
authors.forename: Maria Paz
authors.initials: MP
authors.lastname: Zafra
authors.affiliation: Department of Immunology, IIS-Fundación Jiménez Díaz, Madrid, Spain.
authors.forename: Ainara
authors.initials: A
authors.lastname: Rojas Marco
authors.affiliation: CIBER de Enfermedades Respiratorias (CIBERES), Madrid, Spain; Allergy Department, IIS-Fundación Jiménez Díaz, Madrid, Spain.
authors.forename: Mar
authors.initials: M
authors.lastname: Fernández-Nieto
authors.affiliation: Department of Immunology, IIS-Fundación Jiménez Díaz, Madrid, Spain; CIBER de Enfermedades Respiratorias (CIBERES), Madrid, Spain.
authors.forename: Veronica
authors.initials: V
authors.lastname: Sanz
authors.affiliation: Centro Nacional de Investigaciones Cardiovasculares, Madrid, Spain.
authors.forename: María
authors.initials: M
authors.lastname: Mittelbrunn
authors.affiliation: Department of Biochemistry, Instituto de Investigaciones Biomédicas Alberto Sols, CSIC-UAM, Facultad de Medicina, Universidad Autónoma de Madrid, Madrid, Spain.
authors.forename: Manuel
authors.initials: M
authors.lastname: Izquierdo
authors.affiliation: Centro Nacional de Investigaciones Cardiovasculares, Madrid, Spain.
authors.forename: Francesc
authors.initials: F
authors.lastname: Baixaulli
authors.affiliation: CIBER de Enfermedades Respiratorias (CIBERES), Madrid, Spain; Allergy Department, IIS-Fundación Jiménez Díaz, Madrid, Spain.
authors.forename: Joaquín
authors.initials: J
authors.lastname: Sastre
authors.affiliation: Department of Immunology, IIS-Fundación Jiménez Díaz, Madrid, Spain; CIBER de Enfermedades Respiratorias (CIBERES), Madrid, Spain. Electronic address: vpozo@fjd.es.
authors.forename: Victoria
authors.initials: V
authors.lastname: Del Pozo
mesh_terms: D001249:Asthma / Q000175:diagnosis* / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D015415:Biomarkers / Q000032:analysis / Q000378:metabolism; D016022:Case-Control Studies; D002458:Cell Fractionation; D002469:Cell Separation; D054413:Chemokine CCL11 / Q000494:pharmacology; D004804:Eosinophils / Q000187:drug effects / Q000276:immunology / Q000378:metabolism* / Q000648:ultrastructure; D055354:Exosomes / Q000276:immunology / Q000378:metabolism* / Q000648:ultrastructure; D006801:Humans; D007371:Interferon-gamma / Q000494:pharmacology; D046529:Microscopy, Electron, Transmission; D057146:Multivesicular Bodies / Q000276:immunology / Q000378:metabolism* / Q000648:ultrastructure; D053141:Organelle Size; D061251:Primary Cell Culture
chemical_list: D015415:Biomarkers; C515456:CCL11 protein, human; D054413:Chemokine CCL11; D007371:Interferon-gamma
keywords: Asthma; CD63; IFN-γ; biomarker; endosomes; eosinophils; exosomes; lysobisphosphatidic acid; multivesicular bodies; secretion