Skin organ culture as a model to study oxidative stress, inflammation and structural alterations associated with UVB-induced photodamage.

BACKGROUND

Ultraviolet (UV) irradiation is a major cause of skin damage, of long-term alteration of skin metabolism, homoeostasis and physical structure. The analysis of UV-induced pathogenic processes requires in vitro models allowing biochemical studies, and appropriate for the development of novel, accurate diagnosis methods based on non-invasive procedures.

OBJECTIVES

This work was aimed to reproduce the effects of UVB on whole-skin explants ex vivo and to study underlying biochemical mechanisms, especially in correlation with skin autofluorescence.

METHODS

Human skin organ cultures were irradiated with UVB and subjected to enzyme assays, Western blots, solid-phase ELISA, HPLC and fluorescence measurements.

RESULTS

UVB irradiation was found to enhance ROS production, to deplete the pool of low-molecular-weight antioxidants and to decrease the overall antioxidant capacity in the epidermis, in a manner dependent on xanthine-oxidase activity. Epidermal cell proliferation and mitochondrial activity were transiently stimulated. IκB-α was degraded, and the secretion of inflammatory cytokines was drastically increased. Inducible nitric oxide synthase activity was increased in non-irradiated controls, probably due to the mechanical stress of skin excision, and this phenomenon was suppressed by UVB. Autofluorescence measurements revealed alterations of dermal protein crosslinks following UVB irradiation.

CONCLUSIONS

Skin organ culture proved to be an integrated model appropriate for in vitro analysis of UVB biologic effects and their correlations, and for the study of non-invasive diagnostic methods in cellular and molecular terms.