L-ascorbic acid inhibits UVA-induced lipid peroxidation and secretion of IL-1alpha and IL-6 in cultured human keratinocytes in vitro.
We investigated the antioxidative effect of L-ascorbic acid on lipid peroxidation and on secretion and mRNA expression of IL-1alpha and IL-6 after UVA irradiation (20 J/cm2) in cultured human keratinocytes. Lipid peroxidation was measured by (i) high performance liquid chromatography with UV detection of malondialdehyde (MDA) at 256 nm and (ii) spectrometric measurement of thiobarbituric acid-reactive substances (TBARS). To evaluate UV-induced cytotoxicity, we assessed cell membrane damage by measuring lactate dehydrogenase (LDH) release. UVA-induced lipid peroxidation in cultured human keratinocytes was inhibited by ascorbic acid in a concentration-dependent manner: MDA protein equivalent was reduced by 47% (10(-6)), compared to keratinocytes not exposed to L-ascorbic acid (p < 0.05), and the TBARS showed a concentration-dependent decrease of 49% (10(-6) M) in L-ascorbic acid-supplemented cultures compared to controls (p < 0.05). LDH release was decreased by 45% in L-ascorbic acid-supplemented keratinocyte cultures, indicating protection against cell death (p < 0.05). L-Ascorbic acid was able to downregulate IL-1alpha mRNA expression in both UVA-irradiated and nonirradiated cells; however, IL-6 mRNA expression remained unaffected. The secretion of these cytokines was reduced nearly to normal in the presence of L-ascorbic acid. These findings indicate a major cell-protective effect of L-ascorbic acid on UVA-induced lipid peroxidation and the secretion of pro-inflammatory cytokines by UVA-irradiated human keratinocytes.
Tebbe
B
B
Department of Dermatology, University Medical Center Benjamin Franklin, Free University of Berlin, Germany.
Wu
S
S
Geilen
C C
CC
Eberle
J
J
Kodelja
V
V
Orfanos
C E
CE
D001205:Ascorbic Acid / Q000494:pharmacology*; D002455:Cell Division / Q000187:drug effects; D002462:Cell Membrane / Q000187:drug effects / Q000528:radiation effects; D002478:Cells, Cultured; D005978:Glutathione / Q000032:analysis; D006801:Humans; D007231:Infant, Newborn; D007375:Interleukin-1 / Q000235:genetics / Q000378:metabolism*; D015850:Interleukin-6 / Q000235:genetics / Q000378:metabolism*; D015603:Keratinocytes / Q000737:chemistry / Q000166:cytology / Q000378:metabolism*; D008054:Lipid Peroxides / Q000378:metabolism* / Q000528:radiation effects*; D008297:Male; D010084:Oxidation-Reduction / Q000187:drug effects; D012333:RNA, Messenger / Q000187:drug effects / Q000378:metabolism; D014466:Ultraviolet Rays
D007375:Interleukin-1; D015850:Interleukin-6; D008054:Lipid Peroxides; D012333:RNA, Messenger; D005978:Glutathione; D001205:Ascorbic Acid