Group 2 innate lymphoid cells (ILC2s) are increased in chronic rhinosinusitis with nasal polyps or eosinophilia.
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).


CONCLUSION AND CLINICAL RELEVANCE
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.
['Ho|J|J|', 'Bailey|M|M|', 'Zaunders|J|J|', 'Mrad|N|N|', 'Sacks|R|R|', 'Sewell|W|W|', 'Harvey|R J|RJ|']
D000328:Adult D000368:Aged D000954:Antigens, Surface D016022:Case-Control Studies D002908:Chronic Disease D004802:Eosinophilia D005260:Female D006801:Humans D006967:Hypersensitivity D007113:Immunity, Innate D007073:Immunoglobulin E D016130:Immunophenotyping D007958:Leukocyte Count D016131:Lymphocyte Subsets D008297:Male D008875:Middle Aged D009297:Nasal Mucosa D009298:Nasal Polyps D020556:Neutrophil Infiltration D063868:Patient Outcome Assessment D012220:Rhinitis D012852:Sinusitis D055815:Young Adult
group 2 innate lymphoid cell ILC2 chronic rhinosinusitis nasal polyp tissue eosinophils human