Differential expression of matrix metalloproteinase 2 and 9 in the allergic nasal mucosa and nasal polyps

Abstract

Rationale Allergic rhinitis (AR) and asthma share many similarities in their inflammatory response to allergens. Yet cardinal features of asthma like epithelial shedding, basement membrane thickening and fibrosis are not seen in AR. On the other hand, nasal polyps exhibit several structural changes similar to asthma. We hypothesized that the differential expression of matrix metalloproteinases (MMPs) may contribute to these differences and examined the expression of MMP-2, 9 and 13 in nasal mucosa of AR patients as well as in nasal polyps. Methods By RT-PCR, we examined the mRNA expression of MMP-2, 9 and 13 in the nasal mucosa of AR patients and in nasal polyp tissue. By immunohistochemistry and ELISA, we examined the protein expression, localization and levels of MMP-2, 9 and 13. Results Increased levels of mRNA and protein of MMP-9, but not MMP-2 and 13, was detected in nasal polyps. In the nasal mucosa of AR patients increased levels of MMP-2 and MMP-13 was detected. MMP-2, 9, and 13 in the allergic nasal mucosa was localized to epithelial cells and infiltrating cells. In nasal polyps, MMP-9 was localized to the epithelium, glands and subepithelial infiltrating cells and a good correlation was detected between the levels of MMP-9 and ECP. Conclusions These results suggest that MMP-9 may play an important role in inducing the structural changes seen in nasal polyps and asthma and that the differential expression of MMP-2 and 9 may contribute to the cardinal differences in allergic rhinitis versus asthma and nasal polyps.