Inhibition of interleukin-1 beta production and gene expression in human gingival fibroblasts by low-energy laser irradiation

Human gingival fibroblast (hGF) cells reside in gingival tissues which are challenged frequently by oral bacteria. Lipopolysaccharide (LPS) from perio dontal pathogens can penetrate gingival tissues and stimulate the productio n of interleukin-1 beta (IL-1 beta), which has been implicated in inflammat ion and bone resorption. The anti-inflammatory effects of low-energy laser irradiation have been reported, but the mechanisms of this biostimulatory e ffect have not been fully elucidated. Primary cultured hGF cells were chall enged with LPS isolated from Campylobacter rectus, a known periodontal dise ase-associated pathogen, and irradiated by a Ga-Al-As diode low-energy lase r (830 nm, 3.95-7.90 J/cm(2)). The hGF cells cultured medium showed a marke d elevation of IL-1 beta production by LPS, which was significantly inhibit ed by laser irradiation in a dose-dependent manner. By reverse transcriptio n-polymerase chain reaction (RT-PCR) analysis, this inhibitory effect was i nvolved in the reduction of IL-1 beta mRNA levels but not that of the IL-1 beta converting enzyme.