The role of MMP-2, MMP-9, and TIMP-1 in the pathogenesis of nasal polyps: Immunohistochemical assessment at eight different levels in the epithelial, subepithelial, and deep layers of the mucosa.

We conducted a prospective study to investigate the role of matrix metalloproteinase-2 (MMP-2), matrix metalloproteinase-9 (MMP-9), and tissue inhibitor of metalloproteinase-1 (TIMP-1) in the pathogenesis of nasal polyps. Our study group consisted of 24 patients-21 men and 3 women, aged 23 to 70 years (mean: 45.97 ± 11.60)-with nasal polyposis who underwent functional endoscopic sinus surgery. For comparison purposes, we assembled a control group of 11 patients-6 men and 5 women, aged 18 to 56 years (mean: 29.90 ± 14.22)-without nasal polyps who underwent septoplasty and/or rhinoplasty. We analyzed 36 polyp specimens obtained from the study group (10 from the nasal cavity, 10 from the maxillary sinus, and 16 from the ethmoid sinus) and 11 tissue specimens from the control group (each control provided 1 specimen from the inferior turbinate). We then calculated the mean number of these cells in the epithelium, subepithelial layer of the lamina propria, and the deep paraglandular layer of the mucosa. In general, we found that MMP-2, MMP-9, and TIMP-1 values were higher in the nasal polyp group. These differences became less so as patients' ages and the duration of polyps increased. We conclude that the most important role that MMP-2 plays in polyp growth may be in terms of perivascular localization and an increase in vascular permeability, which causes inflammatory cell migration and edema in the extracellular matrix. An increase in MMP-2 in glandular tissue may lead to hydrolysis of tissue matrix components. The degraded extracellular matrix may result in fibrosis of the polyps. An increase of MMP-9 in the apical part of the epithelium in the polypoid tissue of the nasal cavity, maxillary sinus, and ethmoid sinus may facilitate the epithelial and endothelial cell migration that is observed during polyp development and growth.

The role of platelet-derived growth factor in the pathogenesis of sinonasal polyps: immunohistochemical assessment in epithelial, subepithelial and deep layers of the mucosa.

OBJECTIVES: The aim of this study is to investigate the role of platelet-derived growth factor (PDGF) in the pathogenesis of sinonasal polyps. METHODS: Study group (groups 1-3) consisted of nasal polyp samples of patients with sinonasal polyps and the control group consisted of inferior turbinate samples of patients without nasal polyp. In group 1, 14 specimens from ethmoid sinus; in group 2, 10 specimens from nasal cavity; in group 3, 10 specimens from maxillary sinus; and in group 4 (control), 9 specimens from inferior turbinate were included. By immunohistochemical staining technique, the PDGF positivity index (PI) in mucosal layers and in the inflammatory cells were assessed at the epithelium (EP), subepithelial layer of lamina propria (SE), and deep paraglandular layer of the mucosa (D). RESULTS: Polymorphonuclear cell (PMNC)-percentage (%) values of ethmoid and maxillary sinus, and the PDGF PI from all cells of ethmoid sinus and nasal cavity were significantly higher than those of the control group. As mononuclear cell-% (MNC-%) increased, the PDGF_EP_basal PI, PDGF_SE_endothelial PI, and PDGF_D_endothelial PI decreased. As PMNC-PDGF PI increased, the PDGF_D_perivascular PI decreased and PDGF_D_endothelial PI increased. As PDGF-MNC PI increased, the PDGF_EP_apical PI, PDGF_SE_endothelial PI, and PDGF_D_endothelial PI decreased. As PDGF-all cells (PMNCs, MNCs, and fibroblasts) PI increased, the PDGF_EP_basal PI and PDGF_D_endothelial PI decreased, and the PDGF_D_perivascular PI increased. CONCLUSION: We concluded that the PDGF systems play important roles in polyp pathogenesis. Fibroblast-derived PDGF may be more important than MNC-derived PDGF in polyp developing process. Increased perivascular-PDGF-PI in deep layers of the mucosa may result in sinonasal polyp formation by causing an increase in vascular permeability and extracellular edema, and thus promoting migration of inflammatory cells to extracellular area. Tissue oxygenization may be important for the initiation of PDGF release system. Because of this reason, nasal obstruction should be medically treated earlier, and, if necessary, by surgical approaches.