Collecting Serum, Nasal Lavage Solution, and Nasal Epithelial Tissue

Blood was taken from the abdominal aorta, and 3–5 mL of blood was collected using a 5-mL collection vessel. They were left at room temperature for 3 h and centrifuged at 3,500 rpm for 15 min at 4°C. The supernatant was stored at −80°C until analysis. A self-made instrument for obtaining nasal lavage was inserted from one side of the nose and lavage was collected from the other side of the nose (Fig. 3). When the nasal lavage was taken, the rat’s head was lowered and the face was down. Each mouse was repeatedly washed with 1 mL PBS for 3 times. The nasal epithelial tissues were collected as previously described [30]. First, we removed the fur of the face, put the ophthalmic scissors into the left front nostril, cut the nasal bone along this line to the middle of the forehead, and did the same operation on the right side to disconnect the horizontal ethmoid plate. Then we put the ophthalmic scissors into both sides of the front nostrils, against the nasal bone, cut to the middle of the forehead, and free out of the nasal septum (Fig. 4a, b). Finally, the nasal septum mucosa was collected (Fig. 4c).

Schematic diagram of collecting nasal lavage fluid. a Homemade instrument for collecting nasal lavage fluid. b The process of collecting nasal lavage fluid.

Schematic diagram of collecting nasal mucosa. a The septum initially exposed. b The septum fully exposed. c The nasal mucosa torn from the nasal septum.