Anti-Inflammatory Properties of Narrow-Band Blue Light
July 2006 | Volume 5 | Issue 7 | Original Article | 605 | Copyright © July 2006
Elaine Shnitkind MD, Yaping E PhD, Susan Geen, Alan R. Shalita MD, Wei-Li Lee PhD
Background: Narrow-band blue light (420 nm) has demonstrated safety and efficacy in the treatment of acne vulgaris. It
works by exhibiting a phototoxic effect on the heme metabolism of Propionibacterium acnes. Previous studies using blue light
showed more improvement in inflammatory lesions than in comedones, as well as some improvement on the untreated side.
Cytokines have demonstrated a critical role in the development of inflammation. The expression of pro-inflammatory
cytokines such as IL-1? have been shown to result in the expression of vascular and dermal adhesion molecules, the chemoattraction
of inflammatory cells, and the stimulation of other inflammatory mediators. In addition, UVB radiation serves as a
potent modulator of cell-mediated immune responses.
Purpose: This study investigated the effect of narrow-band blue light on the inflammatory process in the presence and
absence of cytokines and UVB using IL-1? and ICAM-1 as markers for inflammation.
Methods: Two immortalized keratinocyte cell lines were compared: HaCaT, produced by spontaneous immortalization of a
genetically altered cell line, and hTERT, obtained by stable transfection of primary cell culture with human telomerase
reverse transcriptase. Cells were treated with INF-? and TNF-? and exposed to UVB (312 nm at 50 mJ/cm2) and/or blue light
(420 nm at 54 mJ/cm2 and 134 mJ/cm2). The expression of IL-1? and ICAM-1 was measured by quantitative ELISA.
Results: The results showed that blue light and low-dose UVB treatment of HaCaT and hTERT cells resulted in inhibition
of cytokine-induced production of IL-1?. The level of IL-1? decreased by 82% in HaCaT and by 75% in hTERT cells when
exposed to blue light. It decreased by 95% in HaCaT and by 91% in hTERT cells when blue light was used in combination
with UVB. ICAM-1 expression was similarly reduced in HaCaT, but not in hTERT cells.
Conclusions: This study showed that narrow-band blue light has anti-inflammatory effects on keratinocytes by decreasing
the cytokine-induced production of IL-1? and ICAM-1. In addition, blue light demonstrated synergistic effects with lowdose
UVB light. These results expand the properties of narrow-band blue light in modulating the inflammatory process and
will facilitate testing of its phototherapeutic applications in different inflammatory skin conditions.