IADR Abstract Archives
Blue Light Irradiation Influences Reparative Responses in Gingival Fibroblasts
Objectives: Photobiomodulation describes the application of light to influence cellular responses. Prior studies by ourselves have identified trends in reactive oxygen species (ROS) generation in gingival fibroblasts following irradiation with UV-free blue light, which affected cellular metabolic activities. Extending on these findings, the current study investigates whether blue light irradiation and elevated ROS production further influenced additional cellular reparative responses, including antioxidant, growth factor and extracellular matrix (ECM) gene expression.
Methods: Primary human gingival fibroblasts were serum-starved for 24h, prior to irradiation. Irradiances ranged from 3-90J/cm2 generated from combinations of irradiance (mW) and treatment duration. At 6h and 24h post-irradiation, conditioned media from gingival fibroblasts were analysed for hepatocyte growth factor (HGF) and vascular endothelial growth factor (VEGF) protein levels. Gingival fibroblast expression analysis for our genes of interest (COL1A1, COL3A1, BGN, DCN, FN1, HAS2, HAS3, VTN and HGF), were performed by RT-qPCR. At 6h and 24h post-irradiation, gingival fibroblast cell lysates were also extracted for the analysis of GSH, NQO1 and KEAP1 antioxidants by Western blot analysis.
Results: Irradiances >3J/cm2 induced significant dose-dependent increases in HGF gene transcription and protein levels, 24h post-irradiation. Irradiances >36J/cm2 also induced significant increases in VEGF protein levels, 24h post-irradiation. Irradiances >36J/cm2 induced significant upregulation in antioxidant gene expression (GSR, KEAP1 and NQO1), although these changes were not reflected by their protein levels. ECM genes were largely unaffected, although FN1, COL3A1 and HAS2 were downregulated by irradiances >36J/cm2 at 6h and 24h post-irradiation.
Conclusions: There is emerging evidence for use of UV-free blue light to stimulate reparative responses in gingival fibroblasts. Blue light treatments induced significant increases in HGF and VEGF release by gingival fibroblasts. Non-significant changes in cellular antioxidants (GSH, NQO1, KEAP1), suggest that ROS generated during a single irradiation is transient and may not trigger de novo antioxidant transcription.
Methods: Primary human gingival fibroblasts were serum-starved for 24h, prior to irradiation. Irradiances ranged from 3-90J/cm2 generated from combinations of irradiance (mW) and treatment duration. At 6h and 24h post-irradiation, conditioned media from gingival fibroblasts were analysed for hepatocyte growth factor (HGF) and vascular endothelial growth factor (VEGF) protein levels. Gingival fibroblast expression analysis for our genes of interest (COL1A1, COL3A1, BGN, DCN, FN1, HAS2, HAS3, VTN and HGF), were performed by RT-qPCR. At 6h and 24h post-irradiation, gingival fibroblast cell lysates were also extracted for the analysis of GSH, NQO1 and KEAP1 antioxidants by Western blot analysis.
Results: Irradiances >3J/cm2 induced significant dose-dependent increases in HGF gene transcription and protein levels, 24h post-irradiation. Irradiances >36J/cm2 also induced significant increases in VEGF protein levels, 24h post-irradiation. Irradiances >36J/cm2 induced significant upregulation in antioxidant gene expression (GSR, KEAP1 and NQO1), although these changes were not reflected by their protein levels. ECM genes were largely unaffected, although FN1, COL3A1 and HAS2 were downregulated by irradiances >36J/cm2 at 6h and 24h post-irradiation.
Conclusions: There is emerging evidence for use of UV-free blue light to stimulate reparative responses in gingival fibroblasts. Blue light treatments induced significant increases in HGF and VEGF release by gingival fibroblasts. Non-significant changes in cellular antioxidants (GSH, NQO1, KEAP1), suggest that ROS generated during a single irradiation is transient and may not trigger de novo antioxidant transcription.