Parallel expression of macrophage metalloelastase (MMP-12) in duodenal andskin lesions of patients with dermatitis herpetiformis

Background-Dermatitis herpetiformis (DH) is a specific dermatological manif estation of coeliac disease and 80% of DH patients have gluten sensitive en teropathy manifested by crypt hyperplasia and villous atrophy. Matrix degra dation mediated by collagenase 1 (MMP-1) and stromelysin 1 (MMP-3) has prev iously been implicated in the pathobiology of coeliac intestine and cutaneo us DH blisters. Aims-To study expression of stromelysin 2, metalloelastase, collagenase 3, and matrilysin in the intestine and skin of DH patients. Methods-In situ hybridisation using S-35 labelled cRNA probes was performed on duodenal biopsies of 15 DH patients, three samples each of control duod enal or jejunal mucosa, fetal ileal explants, lesional DH skin, and 19 seri al biopsies of experimental DH blisters. Immunostaining was used to examine type IV collagen, macrophages (CD68), and 92 kDa gelatinase (MMP-9) in the specimens. Results-Metalloelastase (MMP-12) was abundantly expressed by subepithelial macrophages in both coeliac intestine and spontaneous and induced DH rash. It was also upregulated in the experimental model of coeliac disease (staph ylococcal endotoxin B stimulated fetal explants). The only other MMP detect ed was MMP-9 which did not colocalise with MMP-12. Conclusions-Upregulation of metalloelastase is associated with T cell media ted immune responses both in the intestine and skin. In addition to modulat ing macrophage migration, it may contribute to degradation of proteoglycans or basement membrane components in the subepithelial mucosa.