Experimental arthritis in rats induces biomarkers of periodontitis which are ameliorated by gene therapy with tissue inhibitor of matrix metalloproteinases.

BACKGROUND: Periodontal disease (PD) and rheumatoid arthritis (RA) share many common pathophysiologic features, but a clinical relationship between the two conditions remains controversial, in part because of the confounding effects of anti-inflammatory drug therapy universally used in the latter disease. To further explore this issue, inflammatory arthritis was induced in rats to determine the effect on gingival biomarkers of inflammation and tissue destruction and to investigate the effect of a therapeutic intervention devoid of conventional anti-inflammatory properties. METHODS: Adjuvant arthritis (AA) was induced in Lewis male rats by injecting mycobacterium cell wall in complete Freund's adjuvant using standard techniques. One group of animals was treated by induction of systemic tissue inhibitor of matrix metalloproteinases (TIMP-4). At 3 weeks, arthritis severity was recorded and both paw and gingival tissues were collected for matrix metalloproteinase activity (MMP) and cytokine analysis. In addition, the maxillary jaws were removed for assessment of periodontal bone loss. RESULTS: The development of arthritis was associated with elevated joint tissue MMPs, tumor necrosis factor (TNF)-alpha, and interleukin (IL)-1beta levels compared to control rats. In the gingival tissue of the untreated arthritic rats, gelatinase, collagenase, TNF-alpha, and IL-1beta were also elevated compared to control rats. Periodontal bone loss and tooth mobility were also increased significantly (P <0.05) in untreated arthritic rats. All parameters improved after TIMP-4 gene therapy. CONCLUSIONS: To our knowledge, this is the first study to report an association between experimental systemic arthritis in rats and elevated gingival tissue MMPs, cytokine levels, and periodontal disease. Reversal of these changes with TIMP-4 gene therapy strengthens the pathophysiologic correlation between systemic and local disease.

Inhibition of alveolar bone loss by matrix metalloproteinase inhibitors in experimental periodontal disease.

Periodontal disease is characterized by excessive host collagenase resulting in loss of gingival and periodontal ligament collagen and adjacent alveolar bone. Intragingival endotoxin injection induces a model of periodontal disease characterized by rapid bone loss with biochemical features similar to that of naturally occurring adult periodontitis. CH1766, a peptide with a zinc binding moeity which fits into the active site of the enzyme, and CH6631, a hydroxamic acid derivative with aryl-substituted sulphonamide residues, are inhibitors of matrix metalloproteinases (MMPIs) with differing inhibitory profiles as characterized by in vitro assays. In this study, endotoxin was injected into the gingivae of rats which were then treated orally with either 3 mg/kg or 30 mg/kg of one of the two inhibitory compounds. The gingival tissues were assessed for collagenase and gelatinase activity, plus three different pro-inflammatory cytokines. In addition, alveolar bone height in defleshed jaws was studied by computerized morphometric analysis and scanning electron microscopy. Both drugs reduced active and/or total MMP activity, in many cases to normal, and also partially normalized cytokine levels as well. A dose-response effect was seen with regard to amelioration of lipopolysaccharide-induced alveolar bone loss with both drugs. Other than studies with tetracyclines, this is the first report of beneficial effects of MMPIs in a model of periodontal disease, strongly suggesting that this class of agents could bring therapeutic benefit to patients with this disorder, and that periodontal disease can be used as a model to demonstrate in vivo efficacy of this class of drugs.