Differential Expression of Matrix Metalloproteinases in Vernal Keratoconjunctivitis, Allergic Asthma and Nasal Polyps

Abstract

Abstract: : Purpose: Allergic conditions in different organs share many similarities in their inflammatory response. Vernal keratoconjunctivitis (VKC), asthma, and nasal polyps exhibit several similar, but site–specific mucosal structural changes. We hypothesized that a differential expression of matrix metalloproteinases (MMP) may contribute to different tissue remodeling aspects in different organs. Methods: Mucosal biopsies from different sources were obtained from: 1) conjunctiva of healthy donors (cCT); 2) tarsal conjunctiva of VKC patients; 3) bronchii of non–asthmatic subjects (bCT); 4) bronchii of mild stable asthmatic patients; 5) nasal mucosa of healthy donors (nCT); 6) nasal polyps of allergic patients. Expression of MMP–1, 3, 9, 13 and TIMP–1 was evaluated by immunohistochemistry. Results: In the normal conjunctiva, tissue expression of MMPs was low or absent, while TIMP–1 was highly expressed. In conjunctival stroma of VKC patients, MMP–1, –9, and –13 were significantly higher expressed compared to respective cCT. MMP–9 and –13 were significantly more expressed in conjunctival epithelium of VKC patients compared to cCT. MMP expression was higher in normal bronchial tissues than in normal conjunctiva. In bronchial tissues, only MMP–13 was significantly more expressed in asthmatic compared to non–asthmatic subjects. In nasal mucosa, MMP–9 staining was higher in polyps then normal nasal mucosa. Compared to respective controls, abnormalities in the epithelial and sub–epithelial structure were more evident in pathologic conjunctiva. Conclusions: MMP–s may play an important role in inducing the structural changes seen in VKC, nasal polyps and asthma. Tissue remodeling was more dramatic in giant papillae of VKC patients compared to other tissue sites of chronic allergic inflammation.

Keywords: conjunctivitis • extracellular matrix • immunohistochemistry