title: Topically applied eicosapentaenoic acid protects against local immunosuppression induced by UVB irradiation, cis-urocanic acid and thymidine dinucleotides.
abstract: UVB-induced immunosuppression, a promoter of photocarcinogenesis, involves the formation of pyrimidine dimers and cis-urocanic acid (cis-UCA), but reactive oxygen species (ROS) also plays an important role. Eicosapentaenoic acid (EPA) can inhibit photocarcinogenesis, but due to its polyunsaturated nature it is susceptible to oxidative damage by ROS. The antioxidant defense system may therefore be challenged upon ultraviolet-B (UVB) irradiation in the presence of EPA. We investigated whether topically applied EPA in mice could protect against local immunosuppression (contact hypersensitivity response to dinitrofluorobenzene) induced by UVB radiation (1.5 J/cm2), or topically applied cis-UCA (150 nmol/cm2) or thymidine dinucleotides (pTpT) (5 nmol/cm2). The influence of EPA on epidermal lipid peroxidation and antioxidant status was also measured. UVB irradiation, cis-UCA and pTpT all caused 70% immunosuppression. Topical pretreatment of mice with EPA partially protected against immunosuppression; the EPA dose needed to accomplish this was 10 nmol/cm2 for UVB irradiation, 100 nmol/cm2 for cis-UCA and 1000 nmol/cm2 for pTpT. Higher EPA doses caused higher UVB-induced lipid peroxidation and lower vitamin C levels. Glutathione only decreased with the highest EPA dose whereas vitamin E was not decreased after UVB irradiation. In conclusion, topically applied EPA protects against UVB-, cis-UCA- and pTpT-induced immunosuppression and maintenance of an adequate antioxidant defense seems to be an important prerequisite for the protective action by EPA.
authors.affiliation: Leiden/Amsterdam Center for Drug Research, Department of Medicinal Photochemistry, Leiden University, P.O. Box 9502, 2300 RA Leiden, The Netherlands. moison_r@chem.leidenuniv.nl
authors.forename: R M
authors.initials: RM
authors.lastname: Moison
authors.forename: D P
authors.initials: DP
authors.lastname: Steenvoorden
authors.forename: G M
authors.initials: GM
authors.lastname: Beijersbergen van Henegouwen
mesh_terms: D000287:Administration, Topical; D000818:Animals; D000975:Antioxidants / Q000378:metabolism; D015118:Eicosapentaenoic Acid / Q000008:administration & dosage*; D005227:Fatty Acids / Q000378:metabolism; D007108:Immune Tolerance / Q000187:drug effects* / Q000528:radiation effects*; D015227:Lipid Peroxidation / Q000187:drug effects / Q000528:radiation effects; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D019301:Oleic Acid / Q000494:pharmacology; D011740:Pyrimidine Dimers / Q000633:toxicity; D014466:Ultraviolet Rays / Q000009:adverse effects; D014560:Urocanic Acid / Q000633:toxicity
chemical_list: D000975:Antioxidants; D005227:Fatty Acids; D011740:Pyrimidine Dimers; D019301:Oleic Acid; D015118:Eicosapentaenoic Acid; D014560:Urocanic Acid