MUC5AC and nasal cavity polyp: Recent studies showed a significant correlation between pendrin, MUC5AC, and eosinophil infiltration in nasal polyps of eosinophil chronic rhinosinusitis patients; nevertheless, almost half of the studied polyps did not present high levels of pendrin, thus leading to the speculation that IL-17 in combination with Th2 cytokines may be necessary for pendrin expression and mucus production in eosinophil chronic rhinosinusitis [134].