Phototherapy in psoriasis: a review of mechanisms of action.
BACKGROUND
Phototherapy is one of the most efficacious treatment options for psoriasis. New, emerging studies are beginning to define the biologic mechanisms by which phototherapy improves psoriasis.


METHODS
To provide an overview of the mechanisms thought to be responsible for the therapeutic effects of phototherapy, a review was performed on all relevant published studies in the Medline database from January 1, 1985, to August 15, 2011.


RESULTS
Four categories of action were proposed in the literature to describe the effects of phototherapy in psoriasis: (1) alteration of the cytokine profile, (2) induction of apoptosis, (3) promotion of immunosuppression, and (4) all other mechanisms.


CONCLUSIONS
Phototherapy acts through a combination of pathways to confer therapeutic benefits in psoriasis, and these different modalities may help explain its particular usefulness in treating this cutaneous disease.
Department of Dermatology, University of California, San Francisco, CA, USA.
Tami
T
Wong
Leon
L
Hsu
Wilson
W
Liao
D017209:Apoptosis / Q000502:physiology; D016207:Cytokines / Q000097:blood; D015536:Down-Regulation / Q000502:physiology; D006801:Humans; D007165:Immunosuppression Therapy; D015603:Keratinocytes / Q000276:immunology; D010789:Phototherapy; D011565:Psoriasis / Q000276:immunology / Q000503:physiopathology / Q000628:therapy*; D013601:T-Lymphocytes / Q000528:radiation effects
D016207:Cytokines