Objective: This study was designed to investigate the effects of S. mutans invasion on Human Coronary Artery Endothelial Cells (HCAEC) wound healing.
Methods: HCAEC cells were seeded in 6-well plates and infected with S. mutans OMZ175, OMZ175:cnm mutant (non-invasive control), or non-infection control. After two hour invasion the cells were wounded across the center of the well, media aspirated, and then treated with antibiotic containing media continuously or pulsed with antibiotic for three hours only. Telemetry analysis on images was used to follow wound closure (0, 24, 48, and 72 hours). ELISAs were used to measure epidermal growth factor receptor (EGF-R) and insulin growth factor (IGF-1) and receptor (IGF-R).
Results: Continuous antibiotic treatment (CAb) was shown to slow the wound closure of HCAEC with a maximum of ~40% wound closure at 72 hours for each group in comparison to ~70% in the pulse antibiotic treatment (PAb). OMZ175 treated cells in the PAb group healed faster than the control at 48 hours, 68% and 50% respectively (p<0.05). IGF-1 secretion was elevated in the OMZ175 and OMZ175:cnm treated cells at 24 hours in comparison to the control with PAb (p<0.05 and p<0.01, respectively). However, IGF-R was reduced by a factor of 10 in the OMZ175 group when compared to the non-infected control and OMZ175:cnm mutant under CAb and no difference in PAb. EGF-R production was found to be significantly higher in OMZ175 than the control and OMZ175:cnm strain (p<0.001) under both CAb and PAb conditions.
Conclusion: HCAEC wound healing was negatively affected by the presence of continuous antibiotic and positively affected by invasive S. mutans. ELISA results suggest that IGF-1 signaling through IGF-R would be reduced in HCAEC intracellularly infected with OMZ175. Consistent with the accelerated wound closure, EGF-R (known to stimulate cell migration and proliferation) levels were elevated in HCAEC OMZ175.
Keywords: Adherence and colonization, Adhesion, Invasion, Oral biology and Wound healing