Abstract:

Objective The expression of heterogenic virulence properties depends on its clonal diversity. The aim of the study was to investigate the mechanism of interleukin -8（IL -8） regulations of oral epithelial cells by challenge of Porphyromonas gingivalis（P.gingivalis） with different fimA genotypes, discuss the relation between fimA genotype and its pathogenicity. Methods P.gingivalis ATCC 33277（type Ⅰ）, W83（type Ⅳ）, 47A -1（type Ⅳ） were assessed for their inductions of IL-8 expression in human oral epithelial cells（KB cell line, ATCC CCL- 17）. KB cells without stimulation of P.gingivalis were used as control group. IL -8 mRNA expression was de - termined by reverse transcription polymerase chain reaction（RT -PCR） at different time intervals（1, 3, 6, 24 h） following continuous co culture of bacteria with KB cell line, and IL -8 protein levels in culture supernatant was determined by enzyme-linked immunosorbent assay.  esults IL-8 mRNA levels were up-regulated and reached its high peak at 1 h following both genotypes infection, then decreased to base level till 24 h. Attenuation of IL-8 protein levels was down-regulated when KB cell co-cultured with both genotypes for 3 h till 24 h, and type Ⅳ was lower than type Ⅰ. IL-8 and IL-6 mRNA expression were not consistent with their protein levels, which indicated post -transcriptional regulations. Conclusion fimA genotypes of P.gingivalis are related with the effect of IL -8 inductions, which indicates fimA genotype is associated with pathogenesis of P.gingivalis.

Key words: Porphyromonas gingivalis, fimA genotype, oral epithelial cell, interleukin-8