Regulation of TGF-β1 on human periodontal fibroblasts in inflammatory state

To investigate the effect of transforming growth factor β1 (TGF-β1) on human periodontal ligament fibroblasts (hPDLFs) stimulated by lipopolysaccharide from Porphyromonas gingivalis (Pg-LPS).

hPDLFs were obtained and identified by immunohistochemistry. The stimulating concentration of Pg-LPS was determined by qRT-PCR and CCK-8. The hPDLFs were divided into 4 groups: blank control group, 100 μg/mL pure Pg-LPS; low concentration group, 1 ng/mL TGF-β1+100 μg/mL Pg-LPS; medium concentration group, 10 ng/mL TGF-β1+100 μg/mL Pg-LPS; and high concentration group 100 ng/mL TGF-β1+100 μg/mL Pg-LPS. Cell proliferation was measured by CCK-8 assay at 72 hours, cell migration was measured by scratch and Transwell chamber assays at 24 hours, and the cell cycle of the hPDLFs was measured by flow cytometry at 72 hours. The expression of Forkhead/winged helix transcription factor p3 (Foxp3), interleukin-6 (IL-6) and Epstein-Barr virus-induced gene 3 (EBI3) mRNA in hPDLFs at 72 hours was measured by qRT-PCR, and the expression of Foxp3, IL-6 and EBI3 proteins in hPDLFs at 72 hours was detected by western blot.

The immunohistochemistry results showed that anti-vimentin was positive and anti-keratin was negative. At a concentration of 100 μg/mL Pg-LPS, the expression of IL-6 mRNA in hPDLFs was increased (P<0.0001), and the proliferation of hPDLFs was decreased (P<0.0001). Therefore, 100 μg/mL PG-LPS was selected to simulate the inflammatory state. 10, 100 ng/mL TGF-β1 could improve the proliferation ability of hPDLFs in inflammatory state (P<0.0001) ; 1, 10 and 100 ng/mL TGF-β1 could promote the migration ability of hPDLFs in inflammatory state (P<0.0001). 1, 10 and 100 ng/mL TGF-β1 could accelerate the cell cycle of hPDLFs in inflammatory state (P<0.0001). 1, 10 and 100 ng/mL TGF-β1 could inhibit the expression of IL-6 gene and protein in hPDLFs in inflammatory state (P<0.0001), 1 and 10 ng/mL TGF-β1 could increase the expression of EBI3 gene and protein in hPDLFs in inflammatory state (P<0.0001). 1, 10 ng/mL TGF-β1 could increase the expression level of Foxp3 gene in hPDLFs in inflammatory state, and 10 ng/mL TGF-β1 could increase the expression level of Foxp3 protein (P<0.05).

TGF-β1 can promote the proliferation and migration of hPDLFs under inflammatory conditions, upregulate EBI3 and inhibit inflammation, which may be related to the expression of the transcription factor Foxp3.