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:
- 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:
- Vitiligo repigmentation depends on the activation, migration, and functional development of primitive melanoblast cells into functional melanocytes.
- 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