Differential expression of remodeling markers by tissue structure in nasal polyposis

Data on the expression and role of matrix metalloproteinases (MMPs) and their tissue inhibitors (tissue inhibitor of metalloproteinases [TIMPs]) in chronic rhinosinusitis with nasal polyps (CRSwNPs) are contradictory, partly because or the use of different techniques of tissue analysis. The aim of this study was to establish a qualitative/semiquantitative method of analysis on the expression of these remodeling markers in different tissue structures and eosinophils in both NPs and nasal mucosa (NM).

NP tissues were obtained from patients undergoing endoscopic sinus surgery for severe CRSwNPs (n = 33) and NM tissues from patients undergoing nasal corrective surgery (n = 12). MMPs (MMP-1, MMP-2, MMP-7, and MMP-9) and TIMP type 1 (TIMP-1) expression were evaluated by immunohistochemistry in tissue structures (epithelium, glands, vessels, and extracellular matrix [ECM]) and eosinophils. Tissue eosinophilia was also analyzed in NP tissues.

MMPs and TIMP-1 expression were found in the epithelium, glands, vessels, and ECM (in both NM and NP) and in eosinophils (only in NP). Significant (p < 0.01) findings were observed in NP compared with NM: increase in MMP-1 in ECM; decrease in MMP-2 in glands, vessels, and epithelium; decrease in MMP-7 in all tissue structures; increase in MMP-9 in ECM and decrease in epithelium and glands; and no differences in TIMP-1. NP tissues showed a clear eosinophilic inflammation compared with NM (p < 0.01).

These findings suggest that (1) metalloproteases (MMP-1, MMP-2, MMP-7, and MMP-9) may play an important role in the remodeling of NPs and/or in NP formation and (2) a differential analysis of tissue structures and inflammatory cells should be performed when studying remodeling marker expression and regulation in the upper airways.