OBJECTIVE To observe the effect of a short course of oral glucocorticoids(GCs)on the expression level of tight junctions(TJs)in the epithelium of nasal polyps.METHODS Patients with chronic rhinosinusitis with nasal polyps(CRSwNP)who were hospitalized for nasal endoscopic surgery were recruited and given oral GCs for 7 consecutive days before surgery.Nasal polyp tissues were harvested before and after GCs treatment respectively.Adult patients who were to undergo nasal endoscopic surgery due to non-inflammatory diseases were selected,and the mucosa of the middle turbinates,inferior turbinates,or uncinate process obtained during surgery was retained as normal controls.Real-time PCR and immunofluorescence confocal microscopy were used to detect the expression of TJs.RESULTS Before oral GCs therapy,the mRNA expression levels of claudin-3,claudin-4,and occludin in nasal polyp specimens were significantly lower than that of normal nasal mucosa.After a short course of oral GCs therapy,the mRNA expression levels of claudin-3 and claudin-4 in nasal polyp specimens were significantly higher than those before treatment.After oral GCs treatment,the protein expression levels of claudin-1 and claudin-4 in nasal polyp tissues were significantly higher than those before treatment.CONCLUSION Compared with normal nasal mucosa,the expression of multiple tight junction proteins in the epithelium of nasal polyps decreases.Short-term oral GCs therapy can significantly up-regulate the expression of tight junction proteins.