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Updated: Aug 7, 2025
Quantification of Hypopigmentation Activity In Vitro
Published on: March 6, 2019
The pigmentation phenotype of melanocytes affects their response to nitric oxide in vitro
Łukasz Marek1, Irena Tam1, Sławomir Kurkiewicz1
1Department of Instrumental Analysis, Faculty of Pharmaceutical Sciences in Sosnowiec, Medical University of Silesia in Katowice, Poland.
Introduction:
It has been shown that nitric oxide (NO) can modulate the immune properties of epidermal melanocytes, and that overexpression of NO in the skin may contribute to inflammation-related pigmentary disorders. Little is known about whether constitutive cell pigmentation affects the sensitivity of melanocytes to NO.
Aim:
To compare the effect of NO on melanin synthesis and the expression of key melanogenesis-related genes in normal human melanocytes of various degrees of constitutive pigmentation.
Material And Methods:
Human epidermal melanocytes derived from lightly and darkly pigmented skin (HEMn-LP and HEMn-DP, respectively) were cultured with or without a NO donor (SPER/NO). Then the total melanin content, the pheomelanin content, the activity and concentration of tyrosinase, and the expressions of TYR and DCT were assessed.
Results:
NO released from SPER/NO did not alter the total amount of melanin produced by cultured cells but increased the proportion of pheomelanin, especially in HEMn-DP. Transcriptional activity of the melanogenesis-related genes, in particular DCT, was downregulated in HEMn-DP and upregulated in HEMn-LP cultured with SPER/NO.
Conclusions:
NO can promote pheomelanogenesis in human epidermal melanocytes, and the cell response in this respect is associated with the pigmentation phenotype. During exposure to NO, melanocytes from dark skin produce much more pheomelanin than lightly pigmented cells. NO-induced overproduction of pheomelanin in the skin could be one of the factors responsible for the greater propensity to develop severe inflammatory dermatoses in dark-skinned individuals, or even melanoma de novo formation based on local chronic inflammation.
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01:28Nitric Oxide Signaling Pathway
01:19Pigmentation
Melanin occurs in two primary forms: eumelanin that provides black and brown pigment and pheomelanin that provides red color. Dark-skinned individuals produce more melanin than those with pale...