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Dark cyclobutane pyrimidine dimers are formed in the epidermis of Fitzpatrick skin types I/II and VI in vivo after exposure to solar-simulated radiation

Research output: Contribution to journalArticlepeer-review

Damilola Fajuyigbe, Thierry Douki, Arjan van Dijk, Robert P.E. Sarkany, Antony R. Young

Original languageEnglish
Pages (from-to)575-584
Number of pages10
JournalPigment Cell and Melanoma Research
Volume34
Issue number3
DOIs
Accepted/In press2021
PublishedMay 2021

Bibliographical note

Funding Information: We thank Dr Su Lwin for taking the biopsies and all the volunteers for their participation. Damilola Fajuyigbe was supported by a PhD studentship from Walgreens Boots Alliance, UK. The funder had no input into the study design, data collection and analysis, the manuscript preparation or journal selection. We also acknowledge the support of the National Institute for Health Research (NIHR) Clinical Research Facility at Guy's & St Thomas' NHS Foundation Trust and the NIHR Biomedical Research Centre based at Guy's and St Thomas' NHS Foundation Trust and King's College London. The views expressed are those of the author(s) and not necessarily those of the NHS, the NIHR or the UK Department of Health. Funding Information: We thank Dr Su Lwin for taking the biopsies and all the volunteers for their participation. Damilola Fajuyigbe was supported by a PhD studentship from Walgreens Boots Alliance, UK. The funder had no input into the study design, data collection and analysis, the manuscript preparation or journal selection. We also acknowledge the support of the National Institute for Health Research (NIHR) Clinical Research Facility at Guy's & St Thomas' NHS Foundation Trust and the NIHR Biomedical Research Centre based at Guy's and St Thomas' NHS Foundation Trust and King's College London. The views expressed are those of the author(s) and not necessarily those of the NHS, the NIHR or the UK Department of Health. Publisher Copyright: © 2021 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd Copyright: Copyright 2021 Elsevier B.V., All rights reserved.

King's Authors

Abstract

Introduction: Unlike “light” cylobutane pyrimidine dimers (CPD) formed during ultraviolet radiation (UVR) exposure, dark CPD (dCPD) are formed afterwards. Studies have attributed this to delayed melanin sensitization. There are no data on the role of melanin in dCPD formation in human skin. Methods and Results: Volunteers of Fitzpatrick skin types (FST I/II vs. VI) were exposed to erythemally equivalent doses of solar simulated radiation. CPD were assessed by semi-quantitative immunostaining in whole epidermis and in three epidermal zones, and quantitative HPLC-MS/MS (whole epidermis) at different times post-exposure up to 24 hr. A CPD peak that appeared at 1–2 hr post-exposure in whole epidermis measurements, in all skin types, demonstrated dCPD. However, both dCPD and light CPD were absent in the basal layer of FST VI with the greatest melanin concentration. Modelling the whole epidermis data showed no differences between the repair kinetics of FST I/II and VI. Discussion: Melanin may be a sensitizer or “sunscreen” for dCPD depending on its location and concentration. Previous CPD repair studies in human skin have assumed peak CPD immediately after UVR exposure and so have overestimated total repair.

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