IL13 and chronic rhinosinusitis without nasal polyps: On the other hand, contrary to our study, Stevens et al. reported that despite the increased gene expression levels of Th2 inflammation mediators, including IL4, IL5, and IL13, when comparing patients with CRSwNP to patients with CRSsNP and controls, there was no difference in the expression of these genes between the AERD and the non-AERD groups of patients with CRSwNP [32].