Although there is evidence that some AMPs are upregulated in CRS patients [16, 17], more recent evidence has indicated that some antimicrobial factors such as palate, lung, and nasal epithelium clone (PLUNC, also named BPIFA1) and sterol O-acyltransferase 1 may be downregulated in patients with CRSwNP [18, 19]. Here, BPIFA1 is linked to chronic rhinosinusitis with nasal polyps.