Non-Invasive Physical Plasma Regulates COX-2 via EP2/EP4 Expression in Periodontal Ligament Cells Under Inflammatory Conditions

Periodontitis is a chronic inflammatory disease characterised by progressive destruction of the periodontal tissues and alveolar bone. Cyclooxygenase-2 (COX-2) plays a key role in the pathogenesis of inflammatory responses via prostaglandin E2 (PGE2) receptors (EP1–4). Non-invasive physical plasma (NIPP) has been shown to modulate cellular activity and exert antimicrobial and anti-inflammatory effects. The aim of this in vitro study was to investigate the impact of NIPP on inflammation- and apoptosis-related molecules, including COX-2, EP2-EP4, Interleukin (IL)-6, IL-8, apoptotic protease activating factor 1 (APAF-1), Caspase (CASP)-3, and CASP-9, IL-10 and B-cell lymphoma 2 (BCL2) in human periodontal ligament cells (hPDLC) under normal and inflammatory conditions. After exposure of hPDLC to IL-1β to mimic inflammation in vitro, cells were treated with NIPP. Gene expression was analysed 24 h post-treatment by quantitative RT-PCR. Protein levels were assessed by ELISA. NIPP significantly inhibited IL-1β-induced upregulation of COX-2, EP2 and EP4 receptors, and APAF-1 mRNA expression in hPDLCs after 24 h. At the protein level, IL-1β-induced expression of COX-2, IL-6 and IL-8 was effectively attenuated by NIPP treatment. In conclusion, our data suggest that NIPP may modulate inflammatory responses in hPDLC, indicating its potential as a promising adjunctive approach for the treatment of periodontitis.