The effect of systemic treatments on periostin expression reflects their interference with the eosinophilic inflammation in chronic rhinosinusitis with nasal polyps

Background: Periostin is a recently discovered biomarker for eosinophilic inflammation. Chronic rhinosinusitis with nasal polyps is a T-helper 2-skewed chronic inflammatory airway disease. Medical treatments aim to relieve symptoms and maintain clinical control by interfering with the inflammatory cascade. The effect on nasal and serum periostin levels is however yet unknown. We aimed to evaluate the effect of omalizumab, mepolizumab, methylprednisolone and doxycycline on nasal and systemic periostin expression. Methods: This study is based on 3 previously published trials. Nasal and systemic periostin were assessed in CRSwNP patients, randomly assigned to receive doxycycline (n=14), methylprednisolone (n=14), mepolizumab (n=20) or omalizumab (n=15).There was a control group for each treatment scheme. Doxycycline (200 mg on the first day, followed by 100 mg once daily) and methylprednisolone (32-8 mg once daily) were administered during 20 days; mepolizumab was injected at baseline and at 4 weeks. Omalizumab was injected every 2 or 4 weeks, following the official drug leaflet. Results: Methylprednisolone and omalizumab significantly reduced serum periostin levels at 4 and 8 weeks, respectively, after the start of the treatment. The effect of methylprednisolone was transient. Nasal periostin levels decreased significantly after 8 weeks of treatment with mepolizumab.The periostin expression is in accordance with the previously reported effect on the eosinophilic inflammation and clinical outcome. Conclusion: All treatment options distinctly influence periostin expression, reflecting the interference with the local or systemic eosinophilic inflammatory cascade.