Fig 1.
Top view of the custom-designed mouse UV irradiation box.
The UV lamp is located above the irradiation box, which has separate compartments to house up to eight mice. A metal-mesh cover (not shown) allows UV light transmission (74% transparency) from above. As shown, during both acclimatization and irradiation, the mice have ad-libitum access to food and water.
Fig 2.
Epidermal thickness in hairless mice skin exposed to UVC light.
A) Representative cross-sectional images of H&E-stained mouse dorsal skin comparing the epidermal thickness in sham-exposed mice (top panel), in mice exposed to 254-nm light (middle panel) or to 207-nm light (bottom panel). B) Quantification of epidermal thickness; values represent the average ± SD of epidermal thickness measured in nine randomly selected fields of view per mouse (n = 3).* p<0.0001.
Table 1.
Summary of the combined results for each endpoint.
Fig 3.
Expression of the proliferative marker Ki-67 in keratinocytes of hairless mice skin exposed to UVC.
A) Ki-67-positive keratinocytes (dark-stained cells) in typical cross-sections of skin of sham-exposed mice (top panel), of mice exposed to 254-nm light (middle panel) or to 207-nm light (bottom panel). B) Quantification of the percentage of keratinocytes expressing Ki-67 antigen; values represent the average ± SD of Ki-67-positive cells measured in six randomly selected fields of view per mouse (n = 3). * p<0.0001.
Fig 4.
UVC-induced pre-mutagenic DNA lesions in hairless mice skin.
A) Representative cross-sectional images of dorsal skin samples comparing pre-mutagenic skin lesions CPD (top row, dark-stained cells) and 6-4PP (bottom row, dark stained cells) in the epidermis of sham-exposed mice (left column), of mice exposed to 254-nm light (middle column) or to 207-nm light (right column). Quantification of the percentage of keratinocytes showing B) CPD or C) 6-4PP dimers; values represent the average ± SD of cells exhibiting dimers measured in nine randomly selected fields of view per mouse (n = 3). * p<0.0001.
Fig 5.
UVC-induced inflammation in hairless mice skin.
Density of A) mast cells and B) cells expressing the myeloperoxidase (MPO) enzyme (i.e. neutrophils) in the epidermis of sham-exposed mice, of mice exposed to 254-nm light or to 207-nm light. Values represent the average ± SD of the number of cells / m2 measured in six randomly selected fields of view per mouse (n = 3). * p <0.0001.
Fig 6.
Tissue differentiation in UVC-exposed hairless mouse skin.
A) Representative cross-sectional images of mouse dorsal epidermis expressing (brown stained area) K6A with B) relative quantification. Mice were sham-exposed (top panel), exposed to 254-nm light (middle panel) or to 207-nm light (bottom panel). Values represent the average ± SD of the percentage of keratin optical density measured in nine randomly selected fields of view per mouse (n = 3). * p <0.0001.