Effect and mechanism of reactive oxygen species-responsive nanoparticles on the regulation of human gingival fibroblast function and inflammation induced by lipopolysaccharide

Abstract

Objective To investigate the effects of PssL-NAC reactive oxygen species (ROS)-responsive nanoparticles on intracellular ROS production, inflammatory factor levels, collagen production, cell function and Toll-like receptor 4 (TLR4), NF-κB nuclear factor-κB (p65) pathway protein expression in human gingival fibroblasts (HGFs) induced by Porphyromonas gingivalis-lipopolysaccharide (P.g-LPS). Methods This study was reviewed and approved by the ethics committee. PssL-NAC microspheres containing oil soluble antioxidant N-acetylcysteine (NAC) were obtained by connecting the hydrophobic end of polycaprolactone (PCL) and the hydrophilic end of polyethylene glycol (PEG) via thioketal (TK) bonds in response to ROS, and self loading in the aqueous and oil phases. After preparation of the PssL-NAC microspheres and aqueous NAC solution, successful synthesis of the nanoparticles was verified by transmission electron microscopy. Then, HGFs were exposed to P.g-LPS (0, 5, or 10 μg/mL), P.g-LPS (0, 5, or 10 μg/mL)+NAC, and P.g-LPS (0, 5, or 10 μg/mL)+PssL-NAC, and the ROS levels in the different groups were observed under confocal microscopy to determine the concentration of P.g-LPS for use in subsequent experiments. The groups were as follows: control group (no treatment), P.g-LPS group (HGFs treated with P.g-LPS), NAC group (HGFs treated with P.g-LPS and NAC), and PssL-NAC group (HGFs treated with P.g-LPS and PssL-NAC). Cell counting kit-8 (CCK-8) assays verified the biosafety of PssL-NAC. The ROS levels in the different groups were detected by DCFH-DA probes and observed via confocal microscopy. Real-time qPCR (RT-qPCR) was used to monitor the gene expression levels of the intracellular inflammatory cytokines interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), collagen 1 (COL1) and collagen 3 (COL3). The effect of PssL-NAC on the migration of HGFs was observed via the scratch test. The protein expression of TLR4-NF-κB, and phosphorylated p65 (p-p65) in the TLR4-NF-κB pathway was evaluated by Western blot. Results PssL-NAC had no significant effect on HGF proliferation (P>0.05). At elevated P.g-LPS concentrations, PssL-NAC maintained intracellular ROS levels approximately twice those in the control group (P0.05) and decreased the protein expression of TLR4 (P<0.001), p65 (P = 0.006), and p-p65 (P = 0.017) in the TLR4-NF-κB pathway. Conclusion PssL-NAC maintains the appropriate intracellular ROS concentration, alleviates P.g-LPS-induced inflammation in HGFs through the TLR4-NF-κB pathway, and restores the cell functions of collagen production and migration in an inflammatory environment.

Keywords

• human gingival fibroblasts，
• reactive oxygen species，
• porphyromonas gingivalis，
• lipopolysaccharide，
• inflammation，
• cell migration，
• nanoparticles，
• collagen，