Effects of glucocorticoid on the expression and regulation of aquaporin 5 in the paranasal sinus of rats with chronic rhinosinusitis

Aquaporins (AQPs) are water-specific membrane channel proteins that regulate water homeostasis for cells and organisms. AQP5 serves an important role in the maintenance of mucosal water homeostasis, and potentially contributes to mucosal edema and inflammation formation in chronic rhinosinusitis (CRS). The aim of the present study was to explore the expression pattern of AQP5 and the effect of glucocorticoids on AQP5 expression in rats with CRS. The rats were randomly divided into three equal groups, as follows: CRS, dexamethasone (dexa) treatment and control groups. A polyvinyl acetal material containing Staphylococcus aureus was inserted into the left nasal cavity of each rat from the CRS and dexa groups. On the 90th post-operative day, the dexa group received dexamethasone (2 mg/kg/day) via intraperitoneal injection for 7 days. The controls did not receive any treatment. The expression of AQP5 in the sinonasal mucosa was determined using immunohistochemistry and quantitative PCR. The immunoreactivities of AQP5 were primarily noted in the epithelial lining and glandular cells, the vascular endothelium and in the goblet cells in the sinonasal mucosa. The AQP5 mRNA expression level was significantly higher in the dexa group than in the control and CRS groups (P=0.006 and P=0.014, respectively). However, no significant difference was indicated between the CRS and control groups (P=0.760). In conclusion, the current study suggests that glucocorticoids induce AQP5 expression in the sinonasal mucosa of CRS rats, which highlights AQP5 as a potential target in the diagnosis and treatment of CRS.