NOS2 and chronic rhinosinusitis: Studies have shown that NOS2 was widely expressed in human bronchial epithelial cells, macrophages, endothelial cells, and vascular smooth muscle cells [14], and abnormal expression of NOS2 was involved in a variety of inflammatory diseases, including asthma, psoriasis, AR, and chronic rhinosinusitis (CRS) [12, 15, 16].