Is collagen breakdown during periodontitis linked to inflammatory cells and expression of matrix metalloproteinases and tissue inhibitors of metalloproteinases in human gingival tissue?

Background: Evidence of the role of matrix metalloproteinases (MMPs) produc ed by resident and inflammatory cells in periodontal destruction is now wel l established. The purpose of this study was to quantify, in healthy and di seased upper gingival connective tissue, the area fraction (AA%) occupied b y collagen fibers, the cell number belonging to inflammatory cell subsets, and the amounts of MMPs and TIMPs (tissue inhibitors of MMPs) in order to i nvestigate the possible correlations, if any, between such molecules, colla gen loss, and inflammatory cell subsets. Methods: Gingival tissue specimens from 6 healthy controls (C) and 6 patien ts with severe periodontitis (P) were divided into 2 groups. The first grou p of specimens was frozen and used for the staining of collagen fibers by s irius red F3Ba and for immunohistochemistry with antibodies against CD8, CD 4, CD22, CD68, and TIA-1 molecules. The second group was used for organ cul ture, zymography, Western blotting, and dot blotting. Morphometric and auto mated image analysis was performed for the evaluation of the area fraction occupied by collagen fibers, the number of inflammatory cell subsets and fo r enzymatic activities developed by MMPs, and the amounts of TIMPs expresse d during periodontal disease. Results: In group P, the area fraction of collagen fibers (33 +/- 10%) was significantly decreased (P <0.0002) when compared to group C (60 +/- 7%), a nd was correlated with the number of all inflammatory cells and amounts of MMPs and TIMPs. In group P, there were significant increases of CD8+, CD22, CD68+, and TIA-1+ cells, as well as increases in the amounts of MMP-1, MM P-2, MMP-3, MMP-9, and the active form of MMP-9. The active form of MMP-9 a nd the amount of TIMP-1 were positively correlated with the number of CD22, CD68+, and TIA-1+ cells. Conclusions: The present study showed an imbalance between MMPs and TIMPs a ssociated with the pathologic breakdown of the extracellular matrix during periodontitis. The active form of MMP-9 could be a marker for the clinical severity of periodontal disease.