POSTN and chronic rhinosinusitis with nasal polyps: Mepolizumab induced sustained, significant reductions in blood eosinophil counts and reduced ECP and IL-5 receptor alpha levels in serum and IL-5 receptor alpha, IL-6, IL-1 beta, myeloperoxidase, and periostin levels in nasal secretions in patients with CRSwNP (82–84).