IL-33 mRNA in induced sputum cells from allergic rhinitis and asthma patients: a marker of Th-2 phenotype status?

Abstract

Introduction: Interleukin-33 (IL-33) is an epithelial ‘alarmin’ inducing a Th2-type reaction, who can be detected by ELISA in supernatants of sputum from asthma patients. Porsbjerg et al. also detected IL-33 mRNA in asthmatics bronchial biopsies. Little is known about the presence of IL-33 mRNA in sputum. Objective: To determine whether IL-33 mRNA is detectable in induced sputum cells from seasonal allergic rhinitis, in asthma patients, and controls. Methods: IL-33 mRNA expression was measured in cell pellets of sputum from 16 asthmatics, 12 seasonal allergic rhinitis and 10 controls by RT-PCR. Exhaled nitric oxide (FENO) and sputum eosinophils were evaluated. Results: The median of IL-33 mRNA expression was 0, 49 and 10 in controls, rhinitis and asthma patients, respectively. There was no difference between allergic rhinitis and asthmatics (p=0.45), who were both significantly higher than controls (p For FENO, levels were 10 ppb 26.8 ppb and 63.5 ppb in controls, rhinitis and asthma patients, respectively. Allergic rhinitis and asthma patients had higher levels than controls (p For eosinophils, levels were 0%, 0% and 10.9% in controls, rhinitis and asthma patients, respectively. Asthmatics had higher levels than control and allergic rhinitis group (p Conclusions: It is shown that IL-33 transcripts are detectable in sputum cells from allergic rhinitis and asthma patients but not from healthy controls. IL-33 epithelial gene expression in lower airways appears linked to markers ofTh-2 phenotype (elevated FENO in both conditions compared to controls) rather than eosinophilic inflammation (elevated in asthmatics only).