Intense pulsed light may improve inflammatory acne through TNF-α down-regulation

Background: Despite many studies on the action of yellow light in acne, its efficacy and mechanisms of action are still unclear. Objectives: To determine if IPL can cause a clinical improvement in acne and whether it modifies TLR2 and TNF alpha expression. Methods: Twenty-one patients with mild to moderate acne involving their backs received 530 nm IPL treatments once every 2 weeks. Assessments at baseline and after the fourth treatment included lesion counts, Leeds grading and SER. Biopsies from the treatment area were taken at three time points. TLR2 expression was determined using immunohistochemistry, and TaqMan (R) Low Density Arrays were used to measure TNF alpha, IL-8 and IL-10. Results: Inflamed lesion counts fell significantly by 28.0% (p = 0.002) but not the Leeds score, SER or non-inflamed lesions. A reduction in TNF alpha expression of 17.6% (p = 0.031) weakly correlated with the change in lesion counts. TLR2 expression fell by 2.6% (p < 0.001) but did not correlate with lesion counts. Neither IL-10 nor IL-8 expression was significantly altered. Conclusions: 530 nm IPL significantly reduces inflammatory lesions, where its efficacy will need optimising to make it a viable treatment option. Its mechanism seems to include a novel anti-TNF alpha effect, independent of IL-10 up-regulation.