Section : Notes de congrès/conférences

The role of melanocytes in skin pigmentation and how they are regulated

  • In mammals, the melanocyte and melanin are responsible hair color and protection of the skin from ultraviolet light (UV).
  • In their development, melanocytes initally derived from neural crest cells, migrate to the basal layer of the epidermis and hair follicles. The migration and proliferation of these cells and the synthesis of melanin is a regulated and complex mechanism.
  • Innate pigmentation is influenced by:
  1. environmental factors such as ultraviolet light and drugs
  2. intrinsic factors such as a number of genes, proteins, hormones and growth factors, some of which include: tyrosinase, TRP1, TRP2, melanocortin 1 receptor (MC1R)  and its agonists, α-MSH, micropthalmia-associated transcription factor (MITF) and Wnt glycoproteins.
  • With all these factors regulating pigmentation, disruption of melanin pathways may result in pigmentary disorders characterized by hyperpigmentation, hypopigmentation or depigmentation.
  • All these diseases are sometimes limited to simple molecular defects and targetted treatment can be conceptualized.
  • In addition to well-established molecules when treating hyperpigmentation (hydroquinone, kojic acid, arbutin,retinoids…), new “biological” agents for hyperpigmentation include MITF antagonists, β-adrenergic receptor and α-MSH receptor antagonists.
  • In the treatment of hypopigmentation and depigmentation, repigmenting agents for vitiligo include afamelanotide, a synthetic analogue of α-MSH and agents reducing oxidative stress.

Contributors

Dr Christophe Hsu – dermatologist. Geneva, Switzerland 2014 (09) – Skin Pigmentation in Health & Disease: Novel and Seasoned Players    
P. Grimes. International Pigment Cell Conference (IPCC). Singapore