The cross-talk between electrophiles, antioxidant defence and the endocannabinoid system in fibroblasts and keratinocytes after UVA and UVB irradiation

• UVB irradiation causes stronger redox imbalance than UVA in keratinocytes and fibroblasts.
• UV irradiation enhances lipid peroxidation, particularly at the level of 4-HNE and 4-HHE.
• UV radiation decreases AEA and 2-AG level as well as their receptor activation.
• Nrf2 activation following UV irradiation varies depending on the skin cell type.
• A potential relationship between UV-induced oxidative stress and the endocannabinoid system is suggested.

BackgroundUV, including UVA and UVB radiation, is one of the most ubiquitous environmental stress factors to human skin and leads to redox imbalance and, consequently, photoaging and cancer development. The aim of the study was to verify which skin cells, keratinocytes or fibroblasts, were more susceptible to UVA or UVB irradiation.ObjectiveKeratinocytes and fibroblasts were subjected to UVA and UVB irradiation.MethodsThe redox potential (superoxide anion generation and antioxidant level/activity), electrophile level and endocannabinoid system were estimated.ResultsThe results presented in this paper demonstrate a strong relationship between UV-induced oxidative stress and changes in the endocannabinoid system. Simultaneously, in irradiated cells, the transcription factors Nrf1, Nrf2 and NFκB are activated to varying degrees. Fibroblasts have a greater susceptibility to ROS generation and transcription factor activation after both UVA and UVB irradiation than keratinocytes. Keratinocytes are more sensitive to changes in the electrophile levels connected with oxidative stress compared to fibroblasts.ConclusionThe differences demonstrated in the response of the tested cells to UV irradiation allow for a better understanding of the mechanisms occurring in the human skin, which may be exploited for future therapies in dermatology.