Er:YAG laser suppresses pro-inflammatory cytokines expression and inflammasome in human periodontal ligament fibroblasts with Porphyromonas gingivalis-lipopolysaccharide stimulation

Background/purpose: Periodontitis is an inflammatory condition of the toothsupporting structures triggered by the host's immune response towards the bacterial deposits around the teeth. It is well acknowledged that pro-inflammatory interleukin (IL) -6, IL -8, MCP-1 as well as the NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome, are the key modulators in the activation of this response. Erbium-doped yttrium -aluminium -garnet (Er:YAG) laser, a solid -state crystal laser have been commonly used in the treatment of periodontal diseases. However, little is understood about the molecular mechanism of the Er:YAG laser, especially in targeting the host immune response brought on by periodontal pathogens. Hence, the current study focused on the protective effects of Er:YAG laser on periodontitis invitro in terms of pro-inflammatory cytokines, chemokines and NLRP3 inflammasome expressions. Materials and methods: Human periodontal ligament fibroblast (PDLFs) were first stimulated with lipopolysaccharides (LPS) from P. gingivalis (Pg-LPS) to simulate periodontitis. Cells were then irradiated with Er:YAG laser of ascending energy densities (3.6-6.3 J/cm(2) ), followed by cell proliferation and wound healing assay. Next, the effects of Er:YAG laser on the expressions of IL -6, IL8, MCP-1, NLRP3, and cleaved GSDMD were examined.