Central compartment of nasal cavity-derived MMP-9 enhances mixed-type 2 inflammation in eosinophilic chronic rhinosinusitis

Chronic rhinosinusitis (CRS) is an inflammatory disease of the upper respiratory tract. Although previously classified based on the presence or absence of nasal polyps, it is now commonly classified by endotype. Eosinophilic CRS (ECRS) is based on type 2 inflammation and the formation of intractable nasal polyps with eosinophil infiltration. Endoscopic surgery is the preferred treatment modality; however, recurrent cases are common. The central compartment of the nasal cavity has been implicated in these recurrences. Notably, the middle turbinate is considered crucial, but discussions have primarily focused on its anatomical significance. To date, there lacks a biochemical perspective on the role of the middle turbinate in recurrence. In this study, we evaluated the role of the middle turbinate as a source of inflammation in ECRS. Differences in gene expression between ECRS and non-ECRS (NECRS) middle turbinates were evaluated using RNA sequencing. Gene changes induced by MMP-9 stimulation of human nasal epithelial cells were also evaluated by RNA sequencing. Comprehensive analysis showed an enhanced IL-4 signaling pathway in the ECRS middle turbinate. Additionally, gene expression of matrix metalloproteinase-9 (MMP-9) was higher in the middle turbinates of patients with ECRS than in those with NECRS (P=0.002). Furthermore, MMP-9 has been found to act on human nasal epithelial cells to enhance pathways such as IL-17, IL-6, and S100 family signaling. MMP-9 in the central compartment of the nasal cavity exacerbates ECRS by induction mixed-type 2 inflammation and airway remodeling.