Red Light Combined with Blue Light Irradiation Regulates Proliferation and Apoptosis in Skin Keratinocytes in Combination with Low Concentrations of Curcumin.

Tianhui Niu,Lizhao Wei,Yan Tian,Qu Ren,Qing Cai,Andrzej T Slominski

doi:10.1371/journal.pone.0138754

Abstract

Curcumin is a widely known natural phytochemical from plant Curcuma longa. In recent years, curcumin has received increasing attention because of its capability to induce apoptosis and inhibit cell proliferation as well as its anti-inflammatory properties in different cancer cells. However, the therapeutic benefits of curcumin are severely hampered due to its particularly low absorption via trans-dermal or oral bioavailability. Phototherapy with visible light is gaining more and more support in dermatological therapy. Red light is part of the visible light spectrum, which is able to deeply penetrate the skin to about 6 mm, and directly affect the fibroblast of the skin dermis. Blue light is UV-free irradiation which is fit for treating chronic inflammation diseases. In this study, we show that curcumin at low concentrations (1.25–3.12 μM) has a strong anti-proliferative effect on TNF-α-induced psoriasis-like inflammation when applied in combination with light-emitting-diode devices. The treatment was especially effective when LED blue light at 405 nm was combined with red light at 630 or 660 nm, which markedly amplified the anti-proliferative and apoptosis-inducing effects of curcumin. The experimental results demonstrated that this treatment reduced the viability of human skin keratinocytes, decreased cell proliferation, induced apoptosis, inhibited NF-κB activity and activated caspase-8 and caspase-9 while preserving the cell membrane integrity. Moreover, the combined treatment also down-regulated the phosphorylation level of Akt and ERK. Taken together, our results indicated that the combination of curcumin with LED blue light united red light irradiation can attain a higher efficiency of regulating proliferation and apoptosis in skin keratinocytes.

Highlights

In recent years, phototherapy with visible light is gaining increasing attention in dermatological practice
To examine whether the treatment of curcumin combined with red united blue light could affect cell proliferation rate, we test the cell viability of HaCaT cells which were pre-incubated with curcumin (0–5 μM) for 2 h and irradiated with blue light, red light or blue light combined with red light for 20 h
Exposure of curcumin-treated cells (1.25–5 μM) to blue light resulted in inhibition of HaCaT cell viability (p

Summary

Introduction

Phototherapy with visible light is gaining increasing attention in dermatological practice. The Light-emitting diodes (LEDs), possessing a very narrow bandwidth, can distribute their biological effects to the defined wavelengths. Red light (wavelength range from 620 nm to 770 nm), which is part of the visible light spectrum, is able to directly impact the fibroblast of the skin dermis due to its capability to deeply penetrate the skin to about 6 mm [2], it is favoured in photodynamic therapy (PDT). Blue light (wavelength range from 400 nm to 480 nm) is UV-free irradiation that shows fewer harmful side effects to mammalian cells than ultraviolet irradiation [3]. Because of the effectiveness in reducing cell proliferation, blue light is propitious to treat hyperplastic diseases and chronic skin inflammation, such as psoriasis, atopic dermatitis and hand- and foot-eczema [4, 5]. The main biological effect of PDT is photochemical effect rather than thermal action [7,8]

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