[Role of heparitinase in the initial stage of gingival inflammation]

For the purpose of elucidating the effect of heparitinase in gingival tissue, paper strips were inserted in the gingival sulcus of a dog and were treated with heparitinase (experimental group), an enzyme-free solution (control group) or inactivated enzyme (control group) for 20 minutes once a day in order to determine the pathohistological changes in the periodontium after 3, 10 and 14 days. No marked difference was noted between the 3-day enzyme-treated group and the control groups, but for the 10-day and 14-day enzyme-treated groups, enlargement of the intercellular epithelium, neutrophil infiltration and inflammatory cellular infiltration, mainly of neutrophils, in the subepithelial connective tissue were observed. Examination of the effect of a tracer, 3H-Dextran, on the permeability of the epithelium to heparitinase revealed incorporation of 3H-Dextran by the enzyme-treated group at about 2 times as much as that by the control group, and there were more silver particles indicative of 3H-Dextran according to autoradiographic findings. Determination of the intratissue location of bacterium-derived heparitinase by the fluorescent antibody technique revealed fluorescence positivity on the gingival sulcus epithelial side but not on the oral epithelial side, and that it was more frequent in the region of the enlarged intercellular area of the upper layer of the gingival sulcus epithelium. These results suggest that bacterium-derived heparitinase present in the epithelium of the gingival sulcus of a dog lowered the defense competence peculiar to the epithelium and elevated of the permeability epithelium to bacterium-produced substances, leading to its involvement in the onset of gingival inflammation by decomposing heparan sulfate, an inter-cellular epithelial matrix.