Blue light irradiation suppresses dendritic cells activation in vitro

Abstract

Additional Supporting Information may be found in the online version of this article: Figure S1. The tobacco extracts exhibited concentration-dependent cytotoxicity to melanocyte culture in more than 20 ll/ml by XTT assay using Cell Proliferation Kit 2 (Roche, Basel, Switzerland) after 24 h culture. Figure S2. Melanocytes cultured with tobacco smoke extract and UVB irradiation. Figure S3. Real-time PCR assay showed a tobacco smoke extract concentration-dependent change in MITF expression (A). Abstract: Blue light is a UV-free irradiation suitable for treating chronic skin inflammation, for example, atopic dermatitis, psoriasis, and hand-and foot eczema. However, a better understanding of the mode of action is still missing. For this reason, we investigated whether dendritic cells (DC) are directly affected by blue light irradiation in vitro. Here, we report that irradiation neither induced apoptosis nor maturation of monocyte-derived and myeloid DC. However, subsequent DC maturation upon LPS/IFNc stimulation was impaired in a dosedependent manner as assessed by maturation markers and cytokine release. Moreover, the potential of this DC to induce cytokine secretion from allogeneic CD4 T cells was reduced. In conclusion, unlike UV irradiation, blue light irradiation at high and low doses only resulted in impaired DC maturation upon activation and a reduced subsequent stimulatory capacity in allogeneic MLRs with strongest effects at higher doses.

Prospective Randomized Long-Term Study on the Efficacy and Safety of UV-Free Blue Light for Treating Mild Psoriasis Vulgaris

“…Recent work has shown that UV-free blue light reduces the proliferation rate of human keratinocytes by inducing differentiation; in addition, it is cytotoxic to T cells at low fluencies that are not harmful to other cells of the skin [5]. Becker et al [6 ]and Fischer et al [7] used blue light to improve the symptoms of eczema patients; in vitro studies by the same group of authors revealed that blue light irradiation suppresses dendritic cell activation. Therefore, UV-free blue light appears to be a promising therapeutic modality in Pv.…”

Prospective, Randomized Study on the Efficacy and Safety of Local UV-Free Blue Light Treatment of Eczema

“…Blue light has been investigated in inflammatory skin diseases like psoriasis, acne, and hand and foot eczema [7,8,9,10]. In contrast to UV therapy no side effects like early photoaging, DNA damage, or inflammation have been observed after blue light irradiation in vitro and in vivo [7,11,12].…”

“…In contrast to UV therapy no side effects like early photoaging, DNA damage, or inflammation have been observed after blue light irradiation in vitro and in vivo [7,11,12]. The only known side effects so far for some patients are a temporary hyperpigmentation of the treated skin areas [9,11].…”

“…After blue light irradiation at 453 nm a reduction in the proliferation rate of endothelial cells and keratinocytes was observed in vitro [13]. In vitro blue light irradiation did not induce Langerhans cell death or T-cell depletion but reduced the potential of dendritic cells to stimulate T cells [7]. Therefore, blue light reduced cytokine expression and stimulated an anti-inflammatory milieu [1,7].…”

“…In vitro blue light irradiation did not induce Langerhans cell death or T-cell depletion but reduced the potential of dendritic cells to stimulate T cells [7]. Therefore, blue light reduced cytokine expression and stimulated an anti-inflammatory milieu [1,7]. Fischer et al [7] postulated that visible blue light treatment for dermatological applications should be safe.…”