In Vitro Investigations on the Effect of Dermal Fibroblasts on Keratinocyte Responses to Ultraviolet B Radiation

Exposure to ultraviolet radiation is closely linked to the development of skin cancers in humans. The ultraviolet B (UVB) radiation wavelength (280–320 nm), in particular, causes DNA damage in epidermal keratinocytes, which are linked to the generation of signature premalignant mutations. Interactions between dermal fibroblasts and keratinocytes play a role in epidermal repair and regeneration after UVB‐induced damage. To investigate these processes, established two and three‐dimensional culture models were utilized to study the impact of fibroblast–keratinocyte crosstalk during the acute UVB response. Using a coculture system it was observed that fibroblasts enhanced keratinocyte survival and the repair of cyclobutane pyrimidine dimers (CPDs) after UVB radiation exposure. These findings were also mirrored in irradiated human skin coculture models employed in this study. Fibroblast coculture was shown to play a role in the expression and activation of members of the apoptotic cascade, including caspase‐3 and Bad. Interestingly, the expression and phosphorylation of p53, a key player in the regulation of keratinocyte cell fate postirradiation, was also shown to be influenced by fibroblast‐produced factors. This study highlights the importance of synergistic interactions between fibroblasts and keratinocytes in maintaining a functional epidermis while promoting repair and regeneration following UVB radiation‐induced damage. Cellular cross‐talk between dermal fibroblasts and epidermal keratinocytes is critical for orchestrating cutaneous repair and regeneration. Herein, we describe the influence of keratinocyte–fibroblast interactions on key processes in the ultraviolet B photoresponse. Importantly, fibroblast‐produced factors were observed to enhance keratinocyte survival and DNA repair by regulating the expression of specific apoptotic and cell cycle regulation proteins.