Effects of 420‐nm intense pulsed light in an acne animal model

Abstract

BACKGROUND: Blue light in the 400-420 nm range has been shown to reduce the levels of Propionibacterium acnes (P. acnes) in the skin. P. acnes has been postulated to be a critical trigger for inflammatory acne. Thus, treatment with 420 nm-intense pulsed light should reduce inflammatory activity in acne. AIM: To evaluate the clinical and histological effects of 420 nm-intense pulsed light treatment on acne in animal model. METHOD: Inflammation acne animal model was constructed by intradermal injection of P. acnes of rat auricular. Levels of tumour necrosis factor alpha (TNF-α) and matrix metalloproteinase 2 (MMP-2), markers of inflammation implicated in acne, were assessed in treated and untreated animals by immunohistochemistry and quantitative polymerase chain reaction (PCR). RESULT: Treatment with 420 nm intense pulsed light led to marked improvement after 6 biweekly treatments. Immunohistochemistry and PCR showed that TNF-α and MMP-2 levels correlated with the extent of acneiform activity and were reduced by treatment with 420 nm light. CONCLUSION: A 420-nm intense pulsed light may exert its beneficial effects on inflammatory acne by reducing the levels of P. acnes and secondarily reducing inflammation induced by the bacteria.