Porphyromonas gingivalis induced DNA oxidative stress damage by iron overload to deplete CTCF expression and prevent osteogenic differentiation of periodontal ligament stem cells.

Abstract

We aimed to investigate the effects of Porphyromonas gingivalis (P. gingivalis) on DNA oxidative damage and osteogenic differentiation of periodontal ligament stem cells (PDLSCs) mediated by iron overload, with special attention to the role of CCCTC-binding factor (CTCF). PDLSCs were co-cultured with different concentrations of P. gingivalis-derived LPS. In addition, deferoxamine (DFO, an iron chelator) or recombinant CTCF protein were used to co-treat PDLSCs. Western blot, immunofluorescence staining, flow cytometry and transmission electron microscopy (TEM) were used to observe the iron overload mediated DNA oxidative damage in PDLSCs. Osteogenic differentiation was assessed based on alkaline phosphatase (ALP) activity, mineralization nodule formation, and bone-related protein expression. CTCF was down-regulated in the gingival tissue of periodontitis patients. P. gingivalis-derived LPS significantly decreased the viability of PDLSCs and suppressed CTCF protein expression, particularly at high concentrations (1 μg/mL 10 μg/mL P. gingivalis-derived LPS). However, co-treatment with DFO alleviated these effects by up-regulating CTCF expression and reducing intracellular iron levels, lipid peroxidation, and DNA damage. Furthermore, P. gingivalis-derived LPS inhibited osteogenic differentiation by decreasing ALP activity, mineralization, and expression levels of bone-associated proteins Runx2, BMP2, BMP4, OPN, and OCN. However, this inhibition was significantly reversed by recombinant CTCF treatment. Our findings underscore the detrimental impact of P. gingivalis on PDLSCs through the suppression of CTCF and highlight the potential therapeutic role of DFO and CTCF in preserving PDLSC function and osteogenic potential.