The use of suction blisters to measure sunscreen protection against UVR-induced DNA damage

Abstract

The formation of DNA photoproducts caused by solar UVR exposure needs to be investigated in-vivo and in particular in order to assess sunscreens' level of protection against solar genotoxicity. The study's purposes were: i) to evaluate if the roof of suction blisters is an appropriate sampling method for measuring photoproducts, and ii) to measure in-vivo sunscreen protection against cyclobutane pyrimidine dimers. Skin areas on the interior forearms of eight healthy volunteers were exposed in-vivo to 2 MED of simulated solar radiation (SSR) and to 15 MED on a sunscreen protected area. After irradiation, six suction blisters were induced and the blister roofs were collected. Analysis of SSR-induced CPDs was performed by two independent methods: a chromatography coupled to mass spectroscopy (HPLC-MS/MS) approach and a 3D-imaging of CPD immunostaining by multiphoton microscopy on floating epidermal sheets. HPLC-MS/MS analyses showed that SSR-unexposed skin presented no CPD dimers, whereas 2 MED SSR-exposed skin showed a significant number of TT-CPD. The sunscreen covered skin exposed to 15 MED appeared highly protected from DNA damage, as the amount of CPD-dimers remained below the detection limit. The multiphoton-immunostaining analysis consistently showed that no CPD staining was observed on the non-SSR-exposed skin. A significant increase of CPD staining intensity and number of CPD-positive cells were observed on the 2 MED SSR-exposed skin. Sunscreen protected skin presented a very low staining intensity and the number of CPD-positive cells remained very close to non-SSR-exposed skin. This study showed that suction blister samples are very appropriate for measuring CPD dimers in-vivo, and that sunscreens provide high protection against UVR-induced DNA damage.

Oxidative Stress and Genotoxicity in Melanoma Induction: Impact on Repair Rather Than Formation of DNA Damage?

“…Considering that the fluence of UVA is 20 times larger than that of UVB in sunlight, it may be estimated to be at the origin of a few percent of the overall load of DNA damage. It has been unambiguously shown by different assays that CPD, but not 64PP or Dewar, were efficiently produced by UVA in human cells and skin (37,(50)(51)(52). CPD is now known to be the most frequent photodamage in the UVA range (32,37,53,54).…”

Nuclear and Urinary Measurements Show the Efficacy of Sun-Protection Factor 50+ Sunscreen against DNA Photoproducts upon Real-Life Recreational Exposure

“…The quantification of photoproducts in the DNA extracted from the roof of suction blisters has previously been used to assess the DNA-protection factor of solar products under laboratory conditions ( Josse et al., 2020 , 2018 ). The same technique was used in this study with natural UVR.…”

“…The first was the detection of pyrimidine dimers in nuclear DNA. This was performed on the roof of suction blisters, an approach that is less invasive for the skin and the donor than classical biopsies ( Josse et al., 2020 , 2018 ). The second and innovative method was the quantification of the pyrimidine dimers released in urine by the DNA-repair machinery ( Reynaud et al., 2022 ).…”

Sub-optimal Application of a High SPF Sunscreen Prevents Epidermal DNA Damage in Vivo

“…A recent study has reported the effect of the same sunscreen at 2 mg/cm 2 after individualised MED-based SSR exposures in skin type I/II volunteers (43). Analyses by HPLC-MS/MS were done on epidermal DNA samples derived from suction blisters.…”