Expression of MMP-9/TIMP-2 in nasal polyps and its functional implications

Nasal polyps (NP) involve tissue repair and structural remodel, both of which require the extracellular matrix. Matrix metalloproteinase (MMP) and tissue inhibitor of metalloproteinase (TIMP) are known regulators for tissue reconstruction. This study therefore aimed to analyze the expressional profile of MMP-9 and TIMP-2 in NP patients, with further investigation of their roles in pathogenesis. A total of 60 NP tissue samples (including 15 type I, 21 type II and 24 type III) were collected from surgeries in our hospital, in addition to 6 normal ethmoid sinus mucosa samples. The mRNA and protein expression levels of MMP-9/TIMP-2 were quantified by real-time PCR and Western blotting, respectively. Serum levels were also checked by enzyme-linked immunosorbent assay (ELISA). Both mRNA and protein levels of MMP-9 in NP tissues or serum were significantly elevated compared to those in control ones (P<0.05) while the TIMP-2 expression was suppressed (P<0.05). In patients with more advanced stage, MMP-9 expression was further elevated, with lowered TIMP-2 levels (P<0.05 in both cases). Pathogenesis and progression of NP is closely related with elevated MMP-9 and suppressed TIMP-2 expression, suggesting the role of those factors as indexes for evaluating NP stage. Our results also provide evidences for further studies of pathogenesis and drug targets of NP.