Extraction of amyloid-like fibrils from chronically inflamed periodontal tissues

Matrix metalloproteinases and their inhibitors in gingival mast cells in persons with and without human immunodeficiency virus infection

BACKGROUND

Mast cells are a prominent cell type in the gingival infiltrate in periodontitis. In this study we examined the expression by gingival mast cells of matrix metalloproteinases, MMP-1, MMP-2, MMP-8 and the tissue inhibitors of metalloproteinases, TIMP-1 and TIMP-2.

METHODS

Gingival specimens from 12 human immunodeficiency virus-negative (HIV-) and 15 HIV-positive (HIV+) patients with chronic marginal periodontitis (CMP), and from 10 HIV- and four HIV+ controls with clinically healthy gingiva (HG) were examined after double immunofluorescence staining for mast cell tryptase, combined with antibodies for MMP-1, MMP-2, MMP-8 or their inhibitors TIMP-1 and TIMP-2.

RESULTS

In the HIV+CMP, HIV+HG and HIV-CMP groups, all mast cells expressed MMP-1 and MMP-8, whereas a smaller proportion (40-60%) in the HIV-HG controls displayed such staining. The former groups also displayed a significantly higher proportion (39-64%) of mast cells expressing MMP-2 as compared with the HIV-HG group (21-31%). All groups displayed similar proportions of TIMP-1 expressing mast cells (86-100%), whereas significantly increased proportions of TIMP-2+ mast cells were seen in the HIV+CMP, HIV+HG and HIV-CMP groups (18-25%) as compared with the HIV-HG group (8-13%). Mast cells were the cell type that most prominently expressed MMP-1 and MMP-8. MMP-2 expression was also strong in mast cells, but was also similarly expressed in other cell types.

CONCLUSION

The chronically inflamed periodontal lesions in the present study appeared with little evidence of mast cell degranulation. The results show, however, that mast cells in inflamed gingiva have the potential to degrade extracellular matrix if appropriately triggered.

Microvasculature in gingivitis and chronic periodontitis: disruption of vascular networks with protracted inflammation

Gingivitis occurring when bacterial plaque accumulates in the gingival crevice provides a convenient and interesting model for chronic inflammation in humans. In some patients, gingivitis progresses to the destructive lesion of periodontitis, involving the formation of periodontal pockets. The basis for pocket formation and progression is not as yet clear, although neutrophilic polymorphonuclear leukocytes (PMN) appear to play a protective role. Vascular changes appear to either facilitate or inhibit PMN function with the effect of either protecting from, or stimulating, periodontitis. Contrary to most circumstances, high endothelial cells in periodontitis are involved with PMN rather than lymphocyte emigration. Expansion of the microvasculature through increased vascular diameter and tortuosity as well as the development of high endothelial cells appears to protect from periodontitis by increasing the supply of both plasma defense factors and PMN to the tissues. Vascular changes that may oppose this and promote periodontitis are the formation of perivascular hyaline material and accumulation of basement membrane rests. The inadequate tissue turnover that accumulation of these vascular products represents can be argued as a vascular response to a chronic inflammation that has failed to eliminate the irritant. It is suggested that these vascular changes may account for the highly localized and burst-like pattern of pocket formation in periodontitis. Finally, it is possible that the recent observation that periodontitis is an independent risk factor for systemic vascular disease may reflect stimulation of acute phase protein synthesis by cytokines released by periodontal high endothelial cells.

Neil Goldsworthy and his legacy: Sydney's Institute of Dental Research

Dr. Neil Goldsworthy had a profound effect on the development of dental research in the biological sciences in Australia, including measures for the prevention of dental caries. He played a major role in the establishment of the Institute of Dental Research in Sydney in 1946 and was Director until his sudden death in 1960. Reviewing the Institute's activities provides the opportunity for his achievements to receive due recognition and to show how they influenced its subsequent development. As one who has been associated with the Institute for most of the last 50 years, it is an honor for me to undertake this task.

Association of amyloid P protein with pathology in periodontal tissues

The lesion of chronic periodontitis is characterized by the persistence of perivascular collections of degenerate plasma cells. In this study, immunohistochemical demonstration of amyloid P (AP) component was used to define the distribution of this protein in established periodontitis lesions and in biopsies of non-destructive marginal gingivitis. Quantitative assessment of AP indicated significantly higher levels in periodontitis than in gingivitis for all regions of the tissue. This was associated with pathology as determined by the intensity of plasma cell accumulation and the extent of connective tissue matrix degradation. AP was concentrated in the deep connective tissue areas but perivascular accumulation was also noted, as was deposition associated with nerve bundles and, occasionally, in the extracellular matrix of the lining epithelium. These findings have potential significance in relation to the pathology of chronic periodontitis as AP has been shown to interact in a calcium-dependent manner with a number of ligands including fibronectin, elastic fibres, C-4 binding protein and amyloid fibrils.