title: Group 2 innate lymphoid cells (ILC2s) are increased in chronic rhinosinusitis with nasal polyps or eosinophilia.
abstract: BACKGROUND
  Chronic rhinosinusitis (CRS) is a heterogeneous disease with an uncertain pathogenesis. Group 2 innate lymphoid cells (ILC2s) represent a recently discovered cell population which has been implicated in driving Th2 inflammation in CRS; however, their relationship with clinical disease characteristics has yet to be investigated.
  
  
  OBJECTIVE
  The aim of this study was to identify ILC2s in sinus mucosa in patients with CRS and controls and compare ILC2s across characteristics of disease.
  
  
  METHODS
  A cross-sectional study of patients with CRS undergoing endoscopic sinus surgery was conducted. Sinus mucosal biopsies were obtained during surgery and control tissue from patients undergoing pituitary tumour resection through transphenoidal approach. ILC2s were identified as CD45(+) Lin(-) CD127(+) CD4(-) CD8(-) CRTH2(CD294)(+) CD161(+) cells in single cell suspensions through flow cytometry. ILC2 frequencies, measured as a percentage of CD45(+) cells, were compared across CRS phenotype, endotype, inflammatory CRS subtype and other disease characteristics including blood eosinophils, serum IgE, asthma status and nasal symptom score.
  
  
  RESULTS
  35 patients (40% female, age 48 ± 17 years) including 13 with eosinophilic CRS (eCRS), 13 with non-eCRS and 9 controls were recruited. ILC2 frequencies were associated with the presence of nasal polyps (P = 0.002) as well as high tissue eosinophilia (P = 0.004) and eosinophil-dominant CRS (P = 0.001) (Mann-Whitney U). They were also associated with increased blood eosinophilia (P = 0.005). There were no significant associations found between ILC2s and serum total IgE and allergic disease. In the CRS with nasal polyps (CRSwNP) population, ILC2s were increased in patients with co-existing asthma (P = 0.03). ILC2s were also correlated with worsening nasal symptom score in CRS (P = 0.04).
  
  
  CONCLUSIONS
  As ILC2s are elevated in patients with CRSwNP, they may drive nasal polyp formation in CRS. ILC2s are also linked with high tissue and blood eosinophilia and have a potential role in the activation and survival of eosinophils during the Th2 immune response. The association of innate lymphoid cells in CRS provides insights into its pathogenesis.
authors.affiliation: St Vincent's Clinical School, Faculty of Medicine, University of New South Wales, Sydney, NSW, Australia; Rhinology and Skull Base Research Group, St Vincent's Centre for Applied Medical Research, University of New South Wales, Sydney, NSW, Australia.
authors.forename: J
authors.initials: J
authors.lastname: Ho
authors.forename: M
authors.initials: M
authors.lastname: Bailey
authors.forename: J
authors.initials: J
authors.lastname: Zaunders
authors.forename: N
authors.initials: N
authors.lastname: Mrad
authors.forename: R
authors.initials: R
authors.lastname: Sacks
authors.forename: W
authors.initials: W
authors.lastname: Sewell
authors.forename: R J
authors.initials: RJ
authors.lastname: Harvey
mesh_terms: D000328:Adult; D000368:Aged; D000954:Antigens, Surface / Q000378:metabolism; D016022:Case-Control Studies; D002908:Chronic Disease; D004802:Eosinophilia / Q000150:complications / Q000276:immunology*; D005260:Female; D006801:Humans; D006967:Hypersensitivity / Q000276:immunology; D007113:Immunity, Innate; D007073:Immunoglobulin E / Q000097:blood / Q000276:immunology; D016130:Immunophenotyping; D007958:Leukocyte Count; D016131:Lymphocyte Subsets / Q000276:immunology* / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D009297:Nasal Mucosa / Q000276:immunology / Q000473:pathology; D009298:Nasal Polyps / Q000150:complications / Q000276:immunology*; D020556:Neutrophil Infiltration / Q000276:immunology; D063868:Patient Outcome Assessment; D012220:Rhinitis / Q000150:complications / Q000276:immunology*; D012852:Sinusitis / Q000150:complications / Q000276:immunology*; D055815:Young Adult
chemical_list: D000954:Antigens, Surface; D007073:Immunoglobulin E
keywords: ILC2; chronic rhinosinusitis; eosinophils; group 2 innate lymphoid cell; human; nasal polyp; tissue