Section : Notes de congrès/conférences

Phototherapy: How does it work ?

  • Phototherapy is widely used in dermatology for the treatment of various skin conditions such as psoriasis, eczema, vitiligo, scleroderma and the list goes on and on.
  • Different light spectrums, such as ultraviolet A (UVA), UVB, narrow band UVB…are used.
  • Although poorly understood, suggested mechanisms are:
  1. Immune suppression (especially for UV): through immunoregulation by Langerhans cells, dermal dendritic cells, and mast cells.
  • Biostimulatory effects of UV radiation such as for vitiligo repigmentation:
  1. Vitiligo repigmentation depends on the activation, migration, and functional development of primitive melanoblast cells into functional melanocytes.
  2. The authors  demonstrated that the capacity of UVB irradiation to induce functional development of melanoblast depends on the irradiance (W/cm2) of the radiation source: the higher the UVB irradiance, the stronger the activation of aryl hydrocarbon receptor pathway. This leads to more prominent epidermal growth factor receptor (EGF-R) nuclear translocation, and initiates tyrosinase transcription and translation while equivalent fluence (J/cm2) delivered by low irradiance UVB failed to do so.

Dr Christophe Hsu – dermatologist. Geneva, Switzerland
2014 (09) – UVB Phototherapy in Vitiligo Treatment: Immune Regulation versus Biostimulation
C. C. E. Lan. International Pigment Cell Conference (IPCC). Singapore