Effect of LPS and IFN-γ transient inflammatory priming on periodontal ligament cells and Schwann cells

This study investigated the effects of Escherichia coli lipopolysaccharide (LPS; 2,000 ng/mL) and interferon-γ (IFN-γ; 50 ng/mL) on human periodontal ligament cells (PDLCs) and mouse Schwann cells (SCs). After a transient inflammatory priming (5 hours), cell migration/proliferation and viability (n = 4) were assessed with scratch and MTT assays, respectively, while inflammatory markers were quantified by real-time quantitative polymerase chain reaction (RT-qPCR; n = 3). Mineralized matrix formation was induced for 12 days and analyzed via Alizarin Red staining (ARS; n = 4) and osteogenesis-related gene expression (RT-qPCR; n = 3). Because of their distinct origins, the two cell lineages were assessed independently. Exposure to LPS+IFN-γ did not affect the viability or migration/proliferation of PDLCs or SCs. In PDLCs, LPS+IFN-γ exposure upregulated interleukin-1α (IL-1α) and interleukin-6 (IL-6), interferon-γ (IFN-γ), IFN-γ receptor (IFN-γR), and tumor necrosis factor (TNF). In SCs, IL-6 and IFN-γR were upregulated, whereas TNF was downregulated compared to the untreated control. Following mineral matrix induction, exposed PDLCs showed increased expression of alkaline phosphatase (ALPL) and runt-related transcription factor 2 (RUNX-2). SCs upregulated ALPL, RUNX-2, and osteocalcin (OCN). Quantitative ARS data indicated that calcium deposition in PDLCs exposed to LPS+IFN-γ was similar to that in the untreated group. SCs exposed to LPS+IFN-γ exhibited significant mineralized matrix formation. Overall, PDLCs responded to LPS+IFN-γ priming with an inflammatory transcriptional response. SCs were unresponsive or showed a downregulated response to inflammatory markers (TNF and IL-1α). Both cell lineages demonstrated mineralized matrix formation after LPS and IFN-γ transient priming.