Superparamagnetic Iron Oxide Nanoparticles Protect Human Gingival Fibroblasts from Porphyromonas gingivalis Invasion and Inflammatory Stimulation

Introduction: Modulating the inflammatory response of human gingival fibroblasts (hGFs) is important for the control of periodontal inflammation because it is a key event in the pathogenesis of periodontitis. Here, we aimed to determine whether polyglucose sorbitol carboxymethyl ether (PSC)-coated superparamagnetic iron oxide nanoparticles (SPIONs) protect hGFs against invasion and inflammatory stimulation by Porphyromonas gingivalis (P. gingivalis).

Methods: First, we determined the cytotoxicity and antimicrobial activity of PSC-SPIONs. Then, their effects on invasion of hGFs by P. gingivalis were evaluated by counting invading P. gingivalis, fluorescence staining, and transmission electron microscopy. The effect of PSC-SPIONs on inflammation in hGFs induced by P. gingivalis lipopolysaccharide was evaluated by measurement of reactive oxygen species (ROS), and enzyme-linked immunosorbent assays, quantitative reverse transcription-polymerase chain reaction, and Western blotting of key indicator molecules. The effects of dimercaptosuccinic acid (DMSA)-coated SPIONs and the free form of PSC alone were also tested and compared with those of PSC-SPIONs.

Results: PSC-SPIONs (25 μg/mL) are cytocompatible with hGFs and exhibit no antimicrobial effects on P. gingivalis. However, they inhibit invasion of hGFs by P. gingivalis at 15 μg/mL. They also decrease ROS production and inflammatory cytokine secretion by hGFs at 5, 15, and 25 μg/mL, by downregulating activation of the nuclear factor-kappa B signaling pathway. Furthermore, PSC alone does not inhibit inflammation, while DMSA-SPIONs do. This indicates that the nanosize effects of PSC-SPIONs, rather than their coating material, play the dominant role in their anti-inflammatory activity.

Conclusion: PSC-SPIONs protect hGFs against P. gingivalis invasion and inflammatory stimulation. Thus, they have potential for clinical application in control of periodontal inflammation.