[Polymorphonuclear leukocyte-mediated effects on human oral keratinocytes by periodontopathic bacterial extracts]

In order to investigate the polymorphonuclear leukocyte-mediated oral keratinocyte injury, the author established a method to culture keratinocytes (SCC9 and gingival keratinocytes) and subjected to the cell detachment assay by polymorphonuclear leukocytes and/or bacterial ultrasonic extracts from Actinobacillus actinomycetemcomitans Y4, Bacteroides forsythus OMZ 408, Fusobacterium nucleatum ATCC 10953, Capnocytophaga sputigena 4 and Eikenella corrodens 1073. The bacterial extracts alone caused no cell disruption of the keratinocyte monolayers. Polymorphonuclear leukocyte alone caused only a minimal cell detachment. On the contrary, when the bacterial extracts were added to the co-culture of keratinocytes and polymorphonuclear leukocytes, cell detachment of keratinocytes was observed except for the bacterial extract from Eikenella corrodens 1073. The effect of Actinobacillus actinomycetemcomitans Y4 was the strongest. This effect was heat labile and not inhibited by polymyxin B. Cell detachment was inhibited by alpha 1-antitrypsin but not by catalase and superoxide dismutase. No keratinocyte lysis was observed in terms of 51Cr release. Hydrogen peroxide and leukocyte elastase also caused keratinocyte detachment. These results indicate that polymorphonuclear leukocyte can cause non-lytic cell detachment of the gingival keratinocytes when encountering some bacteria, which may lead to the increase of the permeability of the keratinocyte layers.