Lipopolysaccharide of Escherichia Coli and Porphyromonas Gingivalis Induced Pro-inflammatory Cytokines in Human Dental Pulp Cells

Objectives: To compare the effect of Escherichia coli Lipopolysaccharide (LPS) and Porphyromonas gingivalis LPS on the expression of inflammatory cytokines by human dental pulp cells (HDPCs).

Methods: HDPCs were stimulated with LPS from either E. coli (1μg/ml) or P. g (1 and 10μg/ml) HDPCs cultured with growth media containing 10% fetal bovine serum as the control group. After 3, 6, 12, and 24 h, the mRNA levels of IL-6, IL-8, IL-1β, COX-2, and TNF-α were measured by quantitative real-time PCR (qRT-PCR). IL-6 concentration in the supernatant of cultured HDPCs was measured by ELISA at 24 h.
Results: As compared with the control group, the mRNA levels of IL-6, IL-8, IL-1β, COX-2, and TNF-α were highly increased after E. coli LPS treatment for 3h (all p<0.05); The mRNA levels of IL-8, IL-1β, and COX-2 were also significantly upgraded after 6h (all p<0.05); whereas no significant differences were observed after 24h. In addition, there was no significant differences in the mRNA expressions of inflammatory cytokines in HDPCs within 24 h between P. g LPS and the control group at 4 time points (all p>0.05).
Conclusions: E. coli LPS (1μg/ml) could induce pro-inflammatory cytokines in HDPCs in the early stages of treatment. However, P. g LPS (1 and 10μg/ml) could not significantly raise pro-inflammatory cytokines in HDPCs within 24h. These findings provide an alternative solution for establishing an in vitro model of inflammatory human dental pulp cells.