Method: THP-1 cells (n = 3) were treated with blue light (45 J/cm2) delivered from a quartz-tungsten-halogen dental curing light (VIP, Bisco, 600 mW/cm2). Controls received no light exposure. Proteins were extracted at 5, 10, 15, 30, and 60 min post-light treatment, then separated by SDS-PAGE, identified by Western blot analysis, and quantified (Odyssey®) to assess blue light-induced changes in levels of HO-1. Parallel experiments were performed to harvest RNA for quantitative RT-PCR analysis of HO-1 mRNA levels. Changes in HO-1 protein or mRNA levels were analyzed by ANOVA and Tukey post-hoc comparisons (α = 0.05).
Result: Western blot analysis revealed that blue light rapidly and significantly elevated HO-1 mRNA levels (p < 0.05) in THP-1 cells. Likewise, HO-1 mRNA levels rapidly increased and peaked with a 2.6-fold increase at 10 min. However, HO-1 mRNA levels remained elevated through the 60 min time point (1.9-fold).
Conclusion: THP-1 monocytic cells respond to blue light exposure by rapidly and significantly increasing production of the cytoprotective HO-1 protein. This response may be useful in limiting inflammation in the oral cavity.
Keywords: Biochemistry, Cell culture, Curing lights, Inflammation and Inflammatory mediators
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