Anti-inflammatory effect of photodynamic therapy using guaiazulene and red lasers on peripheral blood mononuclear cells.

Photodynamic therapy improves oral mucositis treatment. The reactive oxygen species (ROS) generated from this reaction could contribute to an anti-inflammatory effect by suppressing inflammatory cells. To evaluate the anti-inflammatory effect of photodynamic therapy using guaiazulene and a red laser in peripheral blood mononuclear cells (PBMCs). Guaiazulene solutions (1, 2, 5, 25, 35, and 100 μM in 99.8 % methanol) were irradiated with red laser light (625 nm, 146.2 mW/cm2) in continuous mode at 0, 4, and 8 J/cm2 in black 96-well plates. ROS were measured using spin trapping technique with electron spin resonance (ESR) spectroscopy and fluorescence. The two highest concentrations were tested using cell viability (PrestoBlue®) and anti-inflammation (RANTES and PGE2 ELISA) assay kits. Kruskal-Wallis and Dunn Bonferroni tests were used for statistical analyses with significant differences at p-value < 0.05. Guaiazulene solutions between 2 and 5 μM exposed to red laser light at 4-8 J/cm2 generated significantly more singlet oxygen compared to the no guaiazulene group (p < 0.01) and reduced RANTES and PGE2 levels in TNF-α-inflamed peripheral blood mononuclear cells without affecting cell viability. Photodynamic activation of guaiazulene generated singlet oxygen and suppressed inflammatory markers in PBMCs.