Expression of extracellular matrix metalloproteinase inducer in nasal polyps

Extracellular matrix metalloproteinase inducer (EMMPRIN) is a transmembrane glycoprotein that belongs to the immunoglobulin superfamily. The presence of EMMPRIN in nontumoral tissues suggests a role in other physiological and pathological situations, which may be associated with increased matrix metalloproteinase expression. The purpose of this study was to investigate the expression of EMMPRIN mRNA (OMIM *606080) and to localize the EMMPRIN protein in nasal polyps and healthy nasal mucosa. The expression of EMMPRIN was investigated in the nasal polyps of 10 patients undergoing endonasal sinus surgery and compared with nasal mucosal samples obtained from 10 healthy controls. EMMPRIN mRNA was extracted from the tissues, and then a reverse transcription-polymerase chain reaction was performed. Western blot analysis was used to analyze differences in the levels of expression of EMMPRIN protein between patients with nasal polyps and healthy controls, and the EMMPRIN protein was localized in immunohistochemical staining and quantitative analysis of immunopositivity. The levels of expression of EMMPRIN mRNA and protein were significantly increased in patients with nasal polyps compared with healthy controls. EMMPRIN protein was expressed in the epithelium and infiltrating inflammatory cells of nasal polyps and the healthy nasal mucosa. The percentages of the immune-stained area and the number of EMMPRIN-immunopositive inflammatory cells per millimeter were significantly elevated in nasal polyps compared with controls. EMMPRIN is expressed in nasal mucosa and in nasal polyps, and the level of EMMPRIN expression is increased in nasal polyps. These results suggest that the increased expression of EMMPRIN may play a role in the pathogenesis of nasal polyps.