Effect of Various Agents on Oral Bacterial Phagocytosis in THP-1 Cells

Phagocytosis is a fundamental process in which phagocytes capture and ingest foreign particles including pathogenic bacteria. Several oral pathogens have anti-phagocytic strategies, which allow them to escape from and survive in phagocytes. Impaired bacteria phagocytosis increases inflammation and contributes to inflammatory diseases. The purpose of this study is to investigate the influences of various agents on oral pathogenic phagocytosis. To determine phagocytosis, Streptococcus mutans, Fusobacterium nucleatum, Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis were stained with 5-(and-6)-carboxyfluorescein diacetate succinimidyl ester (CFSE), and was measured using flowcytometery and confocal microscopy. The influencing factors on phagocytosis were evaluated through the pretreatment of ROS inhibitor (N-acetyl-L-cysteine (NAC)), lysozyme, potassium chloride (KCI) and adenosine triphosphate (ATP) in THP-1 cells. Expression of pro-inflammatory cytokines was determined by enzyme-linked immunosorbent assay (ELISA). The phagocytosis of various bacteria increased in a MOI-dependent manner. Among the tested bacteria, phagocytosis of P. gingivalis showed the highest fluorescent intensity at same infection time. Among the tested inhibitors, the NAC treatment significantly inhibited phagocytosis in all tested bacteria. In addition, NAC treatment indicated a similar pattern under the confocal microscopy. Moreover, NAC treatment significantly increased the bacteria-induced secretion of IL-1β among the tested inhibitors. Taken together, we conclude that the phagocytosis occurs differently depending on each bacterium. Down-regulation by ROS production inhibited phagocytosis and lead increased of oral pathogens-associated inflammation.

Expression of gingipain K in Porphyromonas gingivalis in the subgingival plaque of puberty gingivitis / 实用口腔医学杂志

Objective:To detect and compare the intensity of gingipain K(Kgp)in culture medium and cell extract of Porphyromonas gingivalis(P.gingivalis)isolates in puberty gingivitis,and then to reveal the possible relationship between Kgp and puberty gingivitis.Methods:36 patients with puberty gingivitis aged from 14 to 17 years were enrolled.Clinical parameters including GI,SBI and PD were evaluated before subgingival plaque samples collection.Subgingival plaque samples were collected and then P.gingivalis isolates were obtained.16S rRNA PCR was used to confirm the presence of P.gingivalis in clinical isolates.Bacteria were cultured in BHI agar base and harvested at the end of log-phase growth.Culture fractions of P.gingivalis(culture medium and cell extracts)were performed with SDS-PAGE and Western blot technique using primary antibody against specific anti-Kgp N-terminal IgG subdomain.The data were statistically analyzed using SPSS 11.5 software.The relationship between the Kgp intensity and the clinical parameters was statistically analyzed using sum rank test.Results:There was positive correlation between the intensity of Kgp N-terminal IgG subdomain and the clinical parameters(P