Comprehensive analysis of melanogenesis and proliferation potential of melanocyte lineage in solar lentigines

Takaaki Yamada, Seiji Hasegawa, Yu Inoue, Yasushi Date, Masaru Arima, Akiko Yagami, Yohei Iwata, Masamichi Abe, Masayuki Takahashi, Naoki Yamamoto, Hiroshi Mizutani, Satoru Nakata, Kayoko Matsunaga, Hirohiko Akamatsu

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Abstract

Background: Solar lentigines (SLs) are characterized by hyperpigmented macules, commonly seen on sun-exposed areas of the skin. Although it has been reported that an increase in the number of melanocytes and epidermal melanin content was observed in the lesions, the following questions remain to be answered: (1) Is acceleration of melanogenesis in the epidermis caused by an increased number of melanocytes or the high melanogenic potential of each melanocyte? (2) Why does the number of melanocytes increase? Objective: To elucidate the pathogenic mechanism of SLs by investigating the number, melanogenic potential and proliferation status of the melanocyte lineage in healthy skin and SL lesions. Methods: Immunostaining for melanocyte lineage markers (tyrosinase, MART-1, MITF, and Frizzled-4) and a proliferation marker, Ki67, was performed on skin sections, and the obtained images were analyzed by image analysis software. Results: The expression level of tyrosinase to MART-1 of each melanocyte was significantly higher in SL lesions than healthy skin. The numbers of melanocytes in the epidermis, melanoblasts in the hair follicular infundibulum and melanocyte stem cells in the bulge region were increased in SL; however, no significant difference was observed in the Ki67-positive rate of these cells. Conclusion: The melanogenic potential of each melanocyte was elevated in SL lesions. It was suggested that the increased number of melanocytes in the SL epidermis might be attributed to the abnormal increase of melanocyte stem cells in the bulge.

Original languageEnglish
Pages (from-to)251-257
Number of pages7
JournalJournal of Dermatological Science
Volume73
Issue number3
DOIs
Publication statusPublished - 01-03-2014

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All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Molecular Biology
  • Dermatology

Cite this

Yamada, T., Hasegawa, S., Inoue, Y., Date, Y., Arima, M., Yagami, A., Iwata, Y., Abe, M., Takahashi, M., Yamamoto, N., Mizutani, H., Nakata, S., Matsunaga, K., & Akamatsu, H. (2014). Comprehensive analysis of melanogenesis and proliferation potential of melanocyte lineage in solar lentigines. Journal of Dermatological Science, 73(3), 251-257. https://doi.org/10.1016/j.jdermsci.2013.11.005