title: Increased collagen degradation by experimentally-induced granulation tissue inoculated with bacteria.
abstract: Periodontitis is characterized by asymptomatic periodic collagen degradation, which is accompanied by the formation of granulation tissue induced by bacteria. The lesions sometimes contain micro-organisms and/or micro-abscesses that are of unknown significance. The aim of this study was to determine whether bacteria in a sterile granulation tissue could enhance its collagenolytic capacity. The formation of granulation tissue was induced by implanting a cellulose sponge in the subcutaneous tissue in the back of the rat. Bacteria were injected every other day into the sponge from day 8 to day 18. The cell-dependent degradation of a homologous 3H-collagen powder enveloped in the sponge was measured by the radioactivity of the urine excreted 8-18 days after the implantation. The injections increased the excretion of radioactivity by about 40% compared with the controls (n = 8, p < or = 0.005), but caused no clinical signs of acute infection or inflammation. On day 18, 2 days after the last injection of bacteria, no bacteria or increased cell infiltration were observed in the granulation tissue. The appearance of the latter could not be distinguished from that of the control tissues injected with buffer alone. It seems reasonable to assume that the increased collagen degradation results from enhanced activity of phagocytes, which may also be related to an increased release of tissue-destructive proteases and free oxygen radicals into the extracellular space. In conclusion, brief recurrent episodes of bacteria in granulation tissue can increase its collagen degrading-capacity. The latter may be due to augmented cell activity in the tissue. This response seems to have some features comparable to the pathogenesis of episodic periodontitis, e.g., by mimicking the collagen degradation.
authors.affiliation: Department of Periodontology, Huddinge University Hospital, Karolinska Institute, Sweden.
authors.forename: B
authors.initials: B
authors.lastname: Asman
authors.forename: P
authors.initials: P
authors.lastname: Wijkander
authors.forename: A
authors.initials: A
authors.lastname: Hjerpe
mesh_terms: D016976:Aggregatibacter actinomycetemcomitans / Q000378:metabolism*; D000818:Animals; D003094:Collagen / Q000378:metabolism* / Q000652:urine; D010450:Endopeptidases / Q000378:metabolism; D005109:Extracellular Matrix / Q000378:metabolism; D005609:Free Radicals / Q000378:metabolism; D006097:Granulation Tissue / Q000378:metabolism / Q000382:microbiology*; D007963:Leukocytes, Mononuclear / Q000382:microbiology; D008297:Male; D010586:Phagocytes / Q000378:metabolism; D010587:Phagocytosis; D051381:Rats; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species / Q000378:metabolism; D012867:Skin / Q000378:metabolism; D015503:Surgical Sponges; D014316:Tritium
chemical_list: D005609:Free Radicals; D017382:Reactive Oxygen Species; D014316:Tritium; D003094:Collagen; D010450:Endopeptidases