Chronic rhinosinusitis (CRS) is a chronic inflammatory condition of the nasal and paranasal sinus mucosa that affects up to 10% of the population worldwide. CRS is the most representative disease of the upper respiratory tract where airway remodeling occurs, including epithelial damage, thickening of the basement membrane, fibrosis, goblet cell hyperplasia, subepithelial edema, and osteitis. CRS is divided into two phenotypes according to the presence or absence of nasal polyps: CRS with nasal polyp (CRSwNP) and CRS without nasal polyps (CRSsNP). Based on the underlying pathophysiologic mechanism, CRS is also classified as eosinophilic CRS and non-eosinophilic CRS, owing to Type 2 T helper (Th2)-based inflammation and Type 1 T helper (Th1)/Type 17 T helper (Th17) skewed immune response, respectively. Differences in tissue remodeling in CRS are suggested to be based on the clinical phenotype and endotypes; this is because fibrosis is prominent in CRSsNP, whereas edematous changes occur in CRSwNP, especially in the eosinophilic type. This review aims to summarize the latest information on the different mechanisms of airway remodeling in CRS according to distinct endotypes.

Chronic rhinosinusitis is an upper respiratory disease during which topical drug treatment via the nasal cavity is the most actively utilized therapeutic strategy. In addition to steroids, antibiotics, and antifungal agents, which are widely used in clinical practice, research on novel topical agents to improve the bacterial biofilm or mucociliary clearance remains ongoing. Moreover, owing to the complex structure of the nasal cavity, the effects of nasal drug delivery vary depending on factors related to delivery fluid dynamics, including device, volume, and compounds. In this article, we review methods and compounds that have been applied to chronic rhinosinusitis management and introduce recent advances and future perspectives in nasal drug delivery for upper respiratory diseases.