Neutrophil-derived metalloproteinase-9 predicts healing quality after sinus surgery

In a recent study, we have shown that gelatinase-B (metalloproteinase [MMP]-9) in nasal secretions can have both monitoring and predictive value on the healing outcome after functional endoscopic sinus surgery (FESS) to treat chronic rhinosinusitis (CRS) and nasal polyposis (NP). In this work, we aimed to explore the source of MMP-9 and the influence of inflammation on MMP-9 expression and release in nasal tissue and secretions during airway remodelling after surgery.

Biopsies from 23 patients operated by FESS for CRS or NP were collected 1, 3, and 6 months after sinus surgery. MMP-9 expression in the paranasal mucosa was correlated with healing quality, with MMP-9 concentrations in nasal fluid, and with histomorphologic findings (edema, fibrosis, alphasmooth muscle actin, CD-68, myeloperoxidase, EG2, and transforming growth factor [TGF]-beta1 stainings).

MMP-9 concentrations in nasal fluid were paralleled by MMP-9 expression inside the extracellular matrix (ECM) after sinus surgery. MMP-9 expression in ECM was significantly correlated with healing quality (r = 0.378, P = .0181), and poor healers presented significantly more edema (P < .05). The amounts of MMP-9 in nasal fluid were significantly and independently predicted by the number of neutrophils (P = .0224) and macrophages (P = .0497) in the tissue. In contrast, MMP-9 expression was not related to fibrosis, number of myofibroblasts, or TGF-beta1 expression in ECM.

MMP-9 expression is increased in the ECM during wound healing and parallels concentrations of MMP-9 in nasal fluids. Inflammatory cells represent the major source of increased MMP-9 expression, which is linked to poor healing quality.