Immunofluorescence (IF) staining
IF staining was performed for paraffin sections of nasal tissue, transwell membranes of ALI culture and cytospin clinical samples. Sample sections were blocked with 10% normal goat serum, then incubated with a primary antibody (Table E1 ) overnight at 4℃, followed by 60 min incubation of Alexa Fluor 488- or Alexa Fluor 594-conjugated secondary antibodies in the dark at room temperature. Mounting medium with 4’6-diamidino-2-phenylindole (DAPI) (Life Technologies, Carlsbad, CA) was used to stain cell nucleus.