Allergic rhinitis is characterized by rhinorrhea, nasal congestion, sneezing and nasal pruritis. Group 2 innate lymphoid cells (ILC2s), CD4 T cells and eosinophils in nasal mucosa are increased significantly after nasal allergen challenge (NAC). Effects of intranasal corticosteroids (INCS) on ILC2s remains to be investigated.
Subjects (n=10) with allergic rhinitis and mild asthma were enrolled in a single-blind, placebo-controlled, sequential treatment study and treated twice daily with intranasaltriamcinolone acetonide(220µg) or placebo for 14 days,separated by a 7-day washout period. Following treatment, subjects underwent NAC and upper airway function was assessed. Cells from the nasal mucosa and blood, sampled 24 hourspost-NAC,underwent flow cytometric enumeration for ILC2s, CD4 T and eosinophil progenitor (EoPs)levels.Cell differentials and cytokine levels were assessed in nasal lavage.
Treatment with INCSsignificantly attenuated ILC2s, IL-5 /IL-13 ILC2s, HLA-DR ILC2s and CD4 T cells in the nasal mucosa, 24h post-NAC. EoPin nasal mucosa were significantly increased, while mature eosinophils were significantly decreased,24h post-NAC in INCS versus placebo treatment arm. Following INCS treatment, IL-2, IL-4, IL-5 and IL-13 were significantly attenuated 24h post-NAC accompanied by significant improvement in upper airway function.
Pre-treatment with INCS attenuates allergen-induced increases in ILC2s, CD4 T cells and terminal differentiation of EoPsin the nasal mucosa of allergic rhinitis patients with mild asthma, with little systemic effect. Attenuation of HLA-DR expression by ILC2s may be an additional mechanism by which steroids modulateadaptive immune responses in the upper airways.

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