Collagenase in the human periodontal ligament

Immunohistochemical detection of matrix metalloproteinase-1 in the periodontal ligament of equine cheek teeth

The hypsodont equine cheek tooth erupts continuously throughout life. The collagen fibers of the periodontal ligament (PDL) have to remodel constantly to allow the tooth to move in an occlusal direction. Remodeling of the collagen fiber bundles needs to be well-coordinated in order to maintain functional tooth support. The aim of this study was to examine the role of matrix metalloproteinase-1 (MMP-1) in the collagen remodeling of the equine PDL under physiological conditions. Specimens containing the PDL interposed between the dental cementum and the alveolar bone were taken from nine Warmblood horses at three designated horizontal levels: subgingival, middle, and apical. The expression of MMP-1 was detected immunohistochemically. MMP-1 was found to be present in the specimens of all horses. Immunopositive fibroblasts/fibrocytes were accumulated within individual single collagen fascicles. Our results suggest that MMP-1 induced collagen degradation plays a central role in the physiological remodeling of the equine PDL. The distribution of MMP-1 positive fascicles indicates well-directed remodeling which occurs as an asynchronous process, so that only single collagen fascicles are remodeled at the same time. Due to this remodeling of one fascicle at a time, the overall anchorage of the tooth is preserved at all times.

The expression of collagen I and XII mRNAs in Porphyromonas gingivalis-induced periodontitis in rats: the effect of doxycycline and chemically modified tetracycline

Tissue remodeling is a dynamic state in which a balance is achieved between the proteolytic breakdown and synthesis of the extracellular matrix. Type I collagen is a major component of the gingival connective tissue (GCT) and the periodontal ligament (PDL) throughout development, while type XII collagen has been found in the mature forms of these tissues. The purpose of this study was to investigate the effects of periodontitis on the expression of type I and XII collagen and subsequently to investigate the effects of doxycycline (DOXY) and chemically modified non-antimicrobial tetracycline (CMT-1) on the expression of these molecules in this model. Adult barrier-raised male Sprague-Dawley rats were inoculated with Porphyromonas gingivalis obtained from humans to create the experimental periodontitis. The animals with the P. gingivalis-induced periodontitis were then split into the following groups: Group A served as infected untreated controls (PGI group); group B was treated with doxycycline (DOXY group); and group C was treated with chemically modified tetracycline-1 (CMT-1 group). Group D contained uninfected animals that served as uninfected controls (NIC group). The expression of type I and XII collagen mRNAs was examined by in situ hybridization in each group, with the co-expression of these molecules representing mature and functional gingival connective tissue. In the NIC group, cells hybridized with digoxygenine-labeled cDNA probes encoding rat alpha2(I) or alpha1(XII) collagens were found distributed uniformly throughout the periodontal connective tissue. The PGI group showed little hybridization in the areas of infection, while both the DOXY and CMT-1 groups showed co-expression of the alpha2(I) and alpha1(XII) probes in the GCT and coronal part of the PDL. This study demonstrates that doxycycline and CMT-1 moderate or reduce the inhibitory effects of periodontal infection on the expression of type I and type XII collagen mRNAs. These results suggest that doxycycline and a form of non-antimicrobial tetracycline, chemically modified tetracycline-1, can reduce periodontal destruction by reversing the inhibitory effect of periodontal infection on collagen synthesis.

Stimulation of enzyme and cytokine production by methyl mercaptan in human gingival fibroblast and monocyte cell cultures

The volatile sulphur compound methyl mercaptan (CH3SH) is a by-product of protein metabolism and a principal component of oral malodour. This investigation examines the effect of CH3SH on the enzymatic activities of cathepsins B and G and elastase, and on the production by human gingival fibroblasts of two key factors, prostaglandin E (PGE) and cAMP, of the PGE2-cAMP-dependent pathway, which may contribute to the increased production of collagenase and tissue destruction in human periodontal disease. The results demonstrate that CH3SH alone, or in combination with interleukin-1 (IL-1) or lipopolysaccharide, can significantly enhance the secretion of PGE2, cAMP and procollagenase by human gingival fibroblasts. CH3SH also stimulated mononuclear cells to produce IL-1, which can increase cAMP production, and act in synergism with the direct effect of CH3SH on cAMP. CH3SH also significantly enhanced the activity of cathepsin B, moderately suppressed that of cathepsin G, but did not significantly affect elastase. These results provide evidence that CH3SH could be a contributing factor in the enzymatic and immunological cascade of events leading to tissue degradation in periodontal diseases.

Tetracyclines inhibit tissue collagenases. Effects of ingested low-dose and local delivery systems

In a series of experiments, Golub et al. demonstrated that tetracyclines, but not other antibiotics, can inhibit mammalian collagenases and proposed that this property could be useful in treating diseases, such as periodontal disease (but also included certain medical conditions, e.g., corneal ulcers) characterized by excessive collagen degradation (J Periodont Res 1983, 1984 and 1985; Experientia 1984; Cornea 1984). One effect was the dramatic reduction of tissue collagenase activity within the gingival crevicular fluid (GCF) of periodontal pockets after administering a standard regimen of a tetracycline (e.g., 200 mg minocycline or 1000 mg tetracycline/day). The preliminary studies described below determined the effect of (1) low-dose (LD; 40-80 mg/day) orally administered minocycline on GCF collagenase activity and on the subgingival microflora (Exp. I), and (2) tetracycline-loaded monolithic fibers (TF) on collagenase activity in vitro (Exp. II). In Exp. I, GCF collagenase activity was reduced by 45 to 80% 2 weeks after initiating LD minocycline therapy, an effect that lasted for at least several weeks after stopping drug treatment. No consistent change in the relative proportions of G(+), G(-) and motile subgingival microorganisms was detected as a result of LD treatment suggesting that the reduction in GCF collagenase activity was a direct inhibition of the enzyme by the drug. In Exp. II, 3- and 6-mm lengths of TF in vitro established tetracycline concentrations in 250 microliters of 132 micrograms/ml, from 3-mm lengths, and 265 micrograms/ml, from 6-mm lengths, after an 18-hour incubation.(ABSTRACT TRUNCATED AT 250 WORDS)

Gingival wound healing in the presence of plaque-induced inflammation

An accelerated loss of connective tissue attachment has been reported following surgery in plaque-infected dentitions. It was the purpose of the present study to evaluate histologically the healing of incisional wounds in the gingival supracrestal region in the presence and absence of bacterially induced inflammation. In the experimental group, marginal periodontitis was induced around the teeth by tying plaque-retentive ligatures at the gingival margins and 10 weeks later an incisional wound was made from within the gingival sulcus to the crest of the bone. In the control group, similar incisional wounds were made in normal gingiva. In each group, three specimens were available for histologic and histometric analysis 1, 3, 7 and 21 days after wounding. In the control group, the wound healing sequence in the supracrestal region was similar to that reported following incisional cutaneous wounds. In the experimental group, epithelial continuity across the wound was re-established earlier, and marked invagination of epithelium occurred into the incision. This invagination was significantly greater than in control specimens at all time points. In addition, within the experimental group a second significant epithelial migration into the wound occurred between 7 and 21 days. The epithelial invagination extended through the major portion of the supracrestal area and terminated near the cementum surface. It is conceivable that marked epithelial invagination into a supracrestal wound may predispose to an accelerated loss of connective tissue attachment.

Identification of a cathepsin b-like protease in the crevicular fluid of gingivitis patients

Crevicular fluid from gingivitis patients contains significant levels of a cysteine protease which was characterized as the lysosomal protease cathepsin B, as judged by substrate specificity, thiol dependence, pH optimum, kinetic parameters, pH stability, and inhibitor sensitivities. A highly-sensitive fluorometric assay procedure was used to establish the mean level of cathepsin B activity for 25 gingivitis patients.