Effect of Enterococcus faecalis lipoteichoic acid on macrophage autophagy

Objective By investigating the effect of Enterococcus faecalis lipoteichoic acid (LTA) on macrophages autophagy, this study aimed to provide experimental evidence for further exploration of the pathogenesis of persistent periapical periodontitis. Methods RAW 264.7 was cultured and cell counting kit-8 (CCK-8) was used to detect the cytotoxicity of LTA. Western blot was used to detect the expression level of autophagy-related protein LC3-Ⅱ/LC3-Ⅰ and Beclin1 and qPCR was applied to detect the expression level of LC3 and Beclin1. RAW 264.7 cell strain stably expressing HBLV-mRFP-GFP-LC3-PURO was established, and laser confocal microscopy was used to observe the formation of autophagosome. SPSS 20.0 statistical software for data analysis. Results The result of CCK-8 showed no obvious toxicity to macrophage when stimulated with 20 μg/mL and the lower concentration of LTA for 24 hours (t = 2.102, P = 0.1106) . After LTA stimulated, Western blot suggested that the expression of LC3-Ⅱ/LC3-Ⅰ (0.42 ± 0.04) and Beclin1 (0.56 ± 0.11) significantly increased with dose-dependent effect (F = 14.25, P<0.001; F = 3.459, P = 0.0258) . In the meanwhile, qPCR results showed that the expression of LC3 (5.94 ± 0.85) and Beclin1 (2.22 ± 0.21) significantly increased with dose-dependent effect (FLC3 = 12.93, PLC3<0.001; FBeclin1 = 6.036, PBeclin1<0.001) after LTA stimulated. Laser confocal microscopy detected that LTA group (58 ± 6) had significant difference (F = 12.36, P = 0.0021) compared with control group (18 ± 8) . Conclusion Enterococcus faecalis LTA may regulate macrophages autophagy with dose-dependent effect. Key words: Enterococcus faecalis; Lipoteichoic acid; Macrophages; Autophagy