Histamine shows potential for vitiligo repigmentation
MedWire News: Research suggests that histamine may stimulate the proliferation and migration of melanocytes in patients with vitiligo.
Histamine may, therefore, provide "the basis for novel therapeutic approaches to vitiligo repigmentation," say study authors Nan-Hyung Kim and Ai-Young Lee (Dongguk University, Korea) in the journal Experimental Dermatology.
Vitiligo is a disorder of pigment resulting from a loss of melanocytes caused by as yet unknown biological mechanisms.
Although exposure to ultraviolet rays has been considered a safe and effective method for repigmentation in patients with vitiligo, new modalities are needed for those patients who do not respond.
Inflammation is frequently accompanied by hyperpigmentation, and histamine has been suggested to play a central role.
In addition previous findings from Kim and Lee's team showed that bee venom stimulates melanocyte proliferation and migration as well as melanogenesis.
Since histamine release is associated with the action of bee venom, its effect on melanocyte proliferation and migration was examined in the current study.
Epidermal specimens were obtained from 13 patients diagnosed with vitiligo using suction blisters and from patients without the disorder for comparative purposes.
Melanocyte proliferation was stimulated across all concentrations with significance achieved at concentrations of 10 µM or greater, reaching a 2.8-fold increase with 10,000 µM of histamine relative to untreated cells.
Meanwhile, melanogenesis was stimulated at lower concentrations between 1 and 100 µM and reduced at concentrations higher than 1000 µM.
To examine the precise action of histamine, the researchers performed assays with agonists or antagonists for three pharmacologically distinct histamine receptor subtypes - H1, H2, and H3.
They found that melanocyte proliferation relied on the H2 receptor coupled with a complex network of signaling involving ERK (extracellular signal-regulated kinase), CREB (cAMP response element-binding), and Akt (RAC-beta serine/threonine-protein kinase) activation, the latter apparently stimulating melanocyte migration.
Furthermore, histamine via the H2 receptor also increased survival of keratinocytes, which have previously been shown to have an increased death rate in vitiligo patients.
The researchers speculate that the proliferation of melanocytes could be regulated by the tissue environment, particularly keratinocytes.
"As keratinocytes produce factors for melanocyte growth, the increase in their survival could also be involved in repigmentation," they comment.
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By Andrew Czyzewski