Collagenase and stromelysin in recurrent aphthous ulcers (RAU).

Six patients with recurrent aphthous ulcers were studied for the presence of matrix metalloproteinases (MMP) 1, 3, and 8 in the lesions and in the clinically unaffected control mucosa obtained from the opposite side. MMP-type specific antisera were applied in the avidin-biotin-peroxidase complex staining method. Neutrophil-type collagenase (MMP-8) was found intracellularly in the connective tissue under the necrotized epithelium, and also laterally to the ulcer in association with the basement membrane. Fibroblast-type collagenase (MMP-1) and stromelysin (MMP-3) were found in the epithelial cells adjacent to the ulcerous lesion. They were found also in the endothelium of capillary blood vessels and postcapillary venules and also in some macrophage- and fibroblast-like mononuclear cells in the lamina propria laterally to the ulcer. A small number of MMP-1 and MMP-3 positive cells were noted in the control biopsies obtained from the clinically uninvolved control mucosa. These findings suggest regional differences in the distribution of the two main collagenases, implying distinct roles in tissue destruction and remodeling.