Inhibition of Interleukin-1β Production and Gene Expression in Human Gingival Fibroblasts by Low-energy Laser Irradiation

Abstract.

Human gingival fibroblast (hGF) cells reside in gingival tissues which are challenged frequently by oral bacteria. Lipopolysaccharide (LPS) from periodontal pathogens can penetrate gingival tissues and stimulate the production of interleukin-1β (IL-1β), which has been implicated in inflammation and bone resorption. The anti-inflammatory effects of low-energy laser irradiation have been reported, but the mechanisms of this biostimulatory effect have not been fully elucidated. Primary cultured hGF cells were challenged with LPS isolated from Campylobacter rectus, a known periodontal disease-associated pathogen, and irradiated by a Ga-Al-As diode low-energy laser (830 nm, 3.95–7.90 J/cm²). The hGF cells cultured medium showed a marked elevation of IL-1β production by LPS, which was significantly inhibited by laser irradiation in a dose-dependent manner. By reverse transcription-polymerase chain reaction (RT-PCR) analysis, this inhibitory effect was involved in the reduction of IL-1β mRNA levels but not that of the IL-1β converting enzyme.