Innate lymphoid cell population distributions and related gene expression characteristics in blood from allergic and nonallergic patients with eosinophilic asthma.

Background: Non-allergic eosinophilic asthma (NAEA) is a distinct subtype of asthma. However, the immune mechanisms associated with NAEA are not yet clearly understood.

Objective: To gain further insight into the pathogenesis of NAEA.

Methods: The proportion of innate lymphoid cells (ILCs) in the blood of patients with allergic eosinophilic asthma (AEA) and NAEA was evaluated. Eosinophilic asthma was defined when fractional exhaled nitric oxide measured at diagnosis (before initiating anti-asthma medications) was greater than 50 ppb. We evaluated the genome-wide gene expression profiles in peripheral blood mononuclear cells obtained at enrollment (in a stable state).

Results: A total of 57 participants were enrolled (10 healthy controls, 23 patients with NAEA, and 24 patients with AEA). We found that the type 1 ILC (ILC1) proportion significantly decreased, but the type 2 ILC (ILC2) and type 3 ILC (ILC3) proportions significantly increased in the blood of both patients with NAEA and those with AEA compared with healthy controls. However, there were no significant differences in the ILC1~3 proportions between NAEA and AEA patients. We also identified distinct biological pathways in patients with NAEA (anti-viral pathway) or AEA (IL-4 and IL-13 signaling and neutrophil degranulation pathways) based on co-expressed gene modules showing significant correlations with the ILC proportions.

Conclusion: ILC proportions in the blood did not differ between NAEA and AEA patients. However, different biological pathways were related to the ILC proportions in these patients. Our results provide further insight into eosinophilic airway inflammation in allergic and non-allergic patients.