Immunolocalization of matrix metalloproteinases and TIMP-1 (tissue inhibitor of metalloproteinases) in human gingival tissues from periodontitis patients

Abstract

The matrix metalloproteinases (MMPs) collagenase, gelatinase A (72 kDa gelatinase), stromelysin, and their specific inhibitor TIMP-1 (tissue inhibitor of metalloproteinases), were immunolocalized using specific polyclonal antisera in gingival tissues from 21 patients with chronic inflammatory periodontal disease. Monoclonal antibodies against macrophages (Leu-M5), B cells (Leu-14), helper T cells (OKT4), suppressor T cells (OKT8) and the HLA-DR epitope were also used to identify leukocyte subsets. MMPs were observed in connective tissues at sites that histologically showed signs of remodelling. The number and distribution of positive cells varied widely, however, not only between individual biopsy specimens, but also within the same specimen. The same was true for the composition and distribution of the inflammatory cell infiltrate. Moreover, although there was a positive correlation between the number of MMP-producing cells and the severity of inflammation in some specimens, for others with comparable leukocyte subset scoring the number was reduced and sometimes absent altogether. Cells secreting MMPs were fibroblasts, macrophages and epithelial cells. It was not possible to determine unequivocally whether a MMP-positive cell within the connective tissue was a fibroblast or a macrophage, since the antisera recognise both fibroblast and macrophage MMPs and the different fixation requirements for MMPs (4% paraformaldehyde) and Leu-M5 (acetone) precluded co-localization on the same section. TIMP-1 was immunolocalized within connective tissue cells at sites of tissue remodelling. Our results support the hypothesis that tissue-derived MMPs may be involved in tissue remodelling in periodontal disease and conclusively demonstrate that epithelial cells may be involved as well as connective tissue cells.