IL17A and chronic rhinosinusitis with nasal polyps: In a study of Chinese CRSwNP patients, IL-4 and IL-13 suppressed Th17 cytokine expression, while IL-17 and TGF-β1 enhanced Th2 cytokines, suggesting that Th2 and Th17 responses may reciprocally modulate each other depending on the local immune environment [5].