title: Similar activation state of neutrophils in sputum of asthma patients irrespective of sputum eosinophilia.
abstract: Inflammatory phenotypes of asthma are associated with differences in disease characteristics. It is unknown whether these inflammatory phenotypes are reflected by the activation status of neutrophils in blood and sputum. We obtained peripheral blood and induced sputum from 21 asthma patients and stratified our samples based on sputum eosinophilia resulting in two groups (>3% eosinophils: n = 13, <3%: n = 8). Eosinophils and neutrophils from blood and sputum were analysed for expression of activation and degranulation markers by flow cytometry. Data were analysed by both classical, non-parametric statistics and a multi-dimensional approach, using principal component analysis (PCA). Patients with sputum eosinophilia were characterized by increased asthma control questionnaire (ACQ) scores and blood eosinophil counts. Both sputum neutrophils and eosinophils displayed an activated and degranulated phenotype compared to cells obtained from blood. Specifically, degranulation of all granule types was detected in sputum cells, combined with an increased expression of the activation markers (activated) Mac-1 (CD11b), programmed death ligand 1 (PD-L1) (CD274) and a decreased expression of CD62L. CD69 expression was only increased on sputum eosinophils. Surface marker expression of neutrophils was similar in the presence or absence of eosinophilia, either by single or multi-dimensional analysis. Sputum neutrophils were highly activated and degranulated irrespective of sputum eosinophilia. Therefore, we conclude that differences in granulocyte activation in sputum and/or blood are not associated with clinical differences in the two groups of asthma patients. The finding of PD-L1 expression on sputum granulocytes suggests an immunomodulatory role of these cells in the tissue.
authors.affiliation: Department of Respiratory Medicine, University Medical Centre Utrecht, Utrecht, the Netherlands.
authors.forename: T
authors.initials: T
authors.lastname: Tak
authors.affiliation: Department of Respiratory Medicine, University Medical Centre Utrecht, Utrecht, the Netherlands.
authors.forename: B
authors.identifier: http://orcid.org/0000-0002-7223-0281
authors.initials: B
authors.lastname: Hilvering
authors.affiliation: Department of Immunology, Laboratory of Translational Immunology, University Medical Centre Utrecht, Utrecht, the Netherlands.
authors.forename: K
authors.initials: K
authors.lastname: Tesselaar
authors.affiliation: Department of Respiratory Medicine, University Medical Centre Utrecht, Utrecht, the Netherlands.
authors.forename: L
authors.initials: L
authors.lastname: Koenderman
mesh_terms: D000328:Adult; D000368:Aged; D015703:Antigens, CD / Q000276:immunology / Q000378:metabolism; D000945:Antigens, Differentiation, T-Lymphocyte / Q000276:immunology / Q000378:metabolism; D001249:Asthma / Q000097:blood / Q000150:complications / Q000276:immunology*; D060890:B7-H1 Antigen / Q000276:immunology / Q000378:metabolism; D039481:CD11b Antigen / Q000276:immunology / Q000378:metabolism; D002470:Cell Survival / Q000276:immunology; D004802:Eosinophilia / Q000097:blood / Q000150:complications / Q000276:immunology; D004804:Eosinophils / Q000276:immunology* / Q000378:metabolism; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D019041:L-Selectin / Q000276:immunology / Q000378:metabolism; D037181:Lectins, C-Type / Q000276:immunology / Q000378:metabolism; D007958:Leukocyte Count; D008297:Male; D008875:Middle Aged; D018375:Neutrophil Activation / Q000276:immunology*; D009504:Neutrophils / Q000276:immunology* / Q000378:metabolism; D025341:Principal Component Analysis; D013183:Sputum / Q000276:immunology* / Q000378:metabolism; D000099192:CD69 Antigens
chemical_list: D015703:Antigens, CD; D000945:Antigens, Differentiation, T-Lymphocyte; D060890:B7-H1 Antigen; D039481:CD11b Antigen; D019041:L-Selectin; D037181:Lectins, C-Type; D000099192:CD69 Antigens
keywords: cell surface molecules; lung; neutrophils