[Effects of Porphyromonas gingivalis lipopolysaccharide on the proliferation and migration of human umbilical artery smooth muscle cells under co-culture conditions]

Objective: To investigate the effects of Porphyromonas gingivalis lipopolysaccharide (Pg-LPS) of type Ⅰand Ⅳ fimA on the proliferation and migration of human umbilical artery smooth muscle cells (HUASMC) under co-culture conditions and to explore the biological basis and possible mechanisms of the relationship between periodontitis and atherosclerosis (As). Methods: Type Ⅰ and Ⅳ fimA Pg were anaerobically cultured and the Pg-LPS was extracted, purified and identified. Human umbilical vein endothelial cells (HUVEC) and HUASMC were cultured in vitro and the HUVEC-HUASMC co-cultured cell model was established using rat tail type Ⅰ collagen. The experiment was divided into three groups: group T1 (co-cultured cells were stimulated with type Ⅰ fimA Pg-LPS at the mass concentrations of 0.5, 1.0, 2.0, 5.0, 10.0 mg/L), group T2 (co-cultured cells were stimulated with type Ⅳ fimA Pg-LPS at the mass concentrations of 0.5, 1.0, 2.0, 5.0, 10.0 mg/L), and negative control group (without LPS). Cell counting kit-8 (CCK-8) was used to detect the proliferation ability of HUASMC and the migration ability of HUASMC was observed by using the Transwell migration chamber. Comparasons of the changes in the proliferation and migration ability of HUASMC after 2, 8, 24 and 48 h of Pg-LPS stimulated co-cultured cells with various mass concentrations of Pg-LPS were conducted. Results: For the co-cultured cells under the action of type Ⅰ and Ⅳ fimA Pg-LPS, at 24 and 48 h, in each mass concentration group of the two types of Pg-LPS (0.5, 1.0, 2.0, 5.0, 10.0 mg/L), HUASMC's A values were significantly up-regulated compared to the negative control group (P<0.05) and for the co-cultured cells after the stimulation of type Ⅳ fimA Pg-LPS at concentrations of 5 and 10 mg/L at 48 h, the A values (1.386±0.044, 1.455±0.058) of HUASMC were significantly higher than that of HUASMC (1.168±0.064, 1.204±0.088) in the same concentrations of type Ⅰ fimA Pg-LPS (P<0.05). In addition, the A values of HUASMC in stimulated co-cultured cells under concentrations of 5.0 and 10.0 mg/L of type Ⅳ fimA Pg-LPS at 48 h were significantly higher than that in stimulated co-culture cells under the concentrations of 0.5 and 1.0 mg/L of type Ⅳ fimA Pg-LPS (1.170±0.082, 1.239±0.089) (P<0.05). The migration results of HUASMC showed that at 8, 24, and 48 h, the numbers of migration of HUASMC in each mass concentration group of type Ⅰ and Ⅳ fimA Pgas-LPS were significantly higher than that of HUASMC under the same Pg-LPS mass concentration at 2 h in the same group (P<0.05). The migration quantities of HUASMC in the other Pg-LPS mass concentration groups at 48 h were significantly higher than that of HUASMC under the same Pg-LPS mass concentration at 24 h in the same group (P<0.05), except for 10.0 mg/L type Ⅳ fimA Pg-LPS. The numbers of HUASMC migration in 2.0 mg/L type Ⅳ fimA Pg-LPS stimulated co-cultured cells at 48 h (204.00±20.98) were significantly higher than that in type Ⅰ fimA Pg-LPS stimulated co-culture cells at the same concentration (141.89±18.28) (P<0.05). Further more, at the same observation time point, the higher the Pg-LPS concentration, the greater the number of HUASMC migration (P<0.05). Conclusions: Both Ⅰ and Ⅳ fimA Pg-LPS could enhance the proliferation and migration ability of HUASMC in the co-culture system, and the virulence of Pg-LPS might be related to the fimA genotype. Ⅳ fimA Pg-LPS showed a more significant stimulating effect and more likely to cause HUASMC dysfunction than Ⅰ fimA Pg-LPS, which provided part of the basis for the progression of As in severe periodontitis.