mTOR Inhibition Prevents Human Gingival Fibroblast from Gingivitis

Objectives: This study examined whether the inhibition of the mammalian target of rapamycin (mTOR) regulated the production of reactive oxidative species (ROS) and inflammatory cytokines stimulated by Porphyromonas gingivalis (P. gingivalis) in human gingival fibroblasts (hGFs).
Methods: hGFs derived from healthy non-periodontitis patients were pre-treated with rapamycin (20nmol/L, 3d) and then stimulated with heat-killed P. gingivalis or live P. gingivalis ATCC 33277. mTOR inhibition was shown by the levels of phosphorylated-S6 in western blotting. The intracellular ROS levels were detected by flow cytometry. The expression of inflammatory cytokines (interleukin (IL)- 1β, IL-6 and IL-8) and antioxidant components (Cat, Sod2 and Prdx3) were assessed by real-time PCR and enzyme-linked immunosorbent assay (ELISA). All the data were statistically analyzed (ANOVA, Dunnett’s, p <0.05).
Results: The results of Western blot revealed that 20nmol/L rapamycin could completely inhibit the mTOR signaling, as assessed by the inhibition of phosphorylation of S6. After P.gingivalis infected, the experimental group significantly decreased the expression levels of IL-1β, IL-6 and IL-8 (p <0.001). And the expression of Cat, Sod2, Prdx3 were increased (p <0.05). On the contrary, the intracellular level of ROS was reduced.
Conclusions: mTOR inhibition may alleviate the anti-inflammatory reaction of hGFs through arresting the intracellular ROS formation and relieving oxidative stress.