Distinct subsets of innate lymphoid cells in nasal polyp

Group 2 innate lymphoid cells (ILC2s) contribute to the pathogenesis of eosinophilic chronic rhinosinusitis with nasal polyps (CRSwNPs). However, the role of other subsets of ILCs and the differentiation of ILCs in CRSwNPs is not well understood. This study aimed to characterize the ILC subsets and evaluate the differentiation of ILCs from ILC precursors (ILCPs) in NP tissue.

ILC subsets and ILCPs were evaluated by flow cytometry in fresh sinonasal mucosa from patients with CRSwNPs and control subjects. Subsets were compared based on clinical variables and immunological features of the patients. Sorted ILCPs (Lin^-CD127⁺CD117⁺CD45RA⁺IL1R1⁺) were cultured with cytokines.

The frequency of ILC1s and IFN-γ-producing ILC1s increased in non-eosinophilic NPs, whereas that of ILC2s and IL-5-producing ILC2s increased in eosinophilic NPs, particularly in patients with comorbid asthma. The frequency of ILC1s and IFN-γ-producing ILC1s, and frequency of ILC2s and IL-5-producing ILC2s positively correlated with that of neutrophils and eosinophils, respectively. The proportion of IFN-γ-producing ILC1s positively correlated with clinical severity and levels of IFN-γ and IL-8. The proportion of IL-5-producing ILC2s positively correlated with levels of IL-5, CCL24, and total IgE. ILCPs were identified in NP tissue and differentiated into IFN-γ-producing or IL-5-producing ILCs in response to increased IL-12 and IL-18 or IL-25 and IL-33 in non-eosinophilic NPs and eosinophilic NPs, respectively.

ILC1s and ILC2s may be associated with neutrophilic and eosinophilic inflammation in CRSwNPs, respectively. In addition, ILCPs located in the sinus mucosa could differentiate into IFN-γ- or IL-5-producing cells in response to local cytokine stimuli.