Clinical and histological effects of blue light on normal skin.
BACKGROUND
Phototherapy with visible light is gaining interest in dermatological practice. Theoretically, blue light could induce biological effects comparable to ultraviolet A (UVA) radiation.


OBJECTIVE
To study the effects of blue light on normal skin in terms of photodamage, skin ageing and melanogenesis.


METHODS
Eight healthy volunteers were included and irradiation with visible blue light was given on five consecutive days. Skin biopsies were analysed with respect to photodamage (p53, vacuolization, sunburn cells), skin ageing (elastosis, MMP-1) and melanogenesis (Melan-A).


RESULTS
No inflammatory cells and sunburn cells were visible before or after irradiation. A significant increase in the perinuclear vacuolization of keratinocytes was demonstrated during treatment (P=0.02) with a tendency towards significance after cessation of treatment (P=0.09). No significant change in p53 expression was seen. Signs of elastosis and changes in MMP-1 expression were absent. Minimal clinical hyperpigmentation of the irradiated skin was confirmed histologically with a significant increase in Melan-A-positive cells (P=0.03).


CONCLUSIONS
Visible blue light, as given in the present study, does not cause deoxyribonucleic acid damage or early photo-ageing. The biological effects of blue light on normal skin are transient melanogenesis and inexplicable vacuolization without resulting apoptosis. In conclusion, the (short-term) use of visible blue light in dermatological practice is safe.
Kleinpenning
Marloes M
MM
Department of Dermatology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands. m.kleinpenning@derma.umcn.nl
Smits
Tim
T
Frunt
Marjolein H A
MH
van Erp
Piet E J
PE
van de Kerkhof
Peter C M
PC
Gerritsen
Rianne M J P
RM
D000328:Adult; D000951:Antigens, Neoplasm / Q000378:metabolism; D005260:Female; D006801:Humans; D008027:Light / Q000009:adverse effects*; D058965:MART-1 Antigen; D008297:Male; D020781:Matrix Metalloproteinase 1 / Q000378:metabolism; D009363:Neoplasm Proteins / Q000378:metabolism; D010789:Phototherapy / Q000009:adverse effects*; D012867:Skin / Q000378:metabolism / Q000473:pathology*; D015595:Skin Aging / Q000473:pathology / Q000528:radiation effects*; D013471:Sunburn / Q000378:metabolism / Q000473:pathology; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism
D000951:Antigens, Neoplasm; D058965:MART-1 Antigen; C548667:MLANA protein, human; D009363:Neoplasm Proteins; D016159:Tumor Suppressor Protein p53; C522360:MMP1 protein, human; D020781:Matrix Metalloproteinase 1