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Effects of low concentrations of cis‐ and trans ‐urocanic acid on cytokine elaboration by keratinocytes
Author(s) -
Redondo P.,
GarcíaFoncillas J.,
Cuevillas F.,
España A.,
Quintanilla E.
Publication year - 1996
Publication title -
photodermatology, photoimmunology and photomedicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.736
H-Index - 60
eISSN - 1600-0781
pISSN - 0905-4383
DOI - 10.1111/j.1600-0781.1996.tb00211.x
Subject(s) - urocanic acid , chemistry , elaboration , cytokine , cis–trans isomerism , stereochemistry , biochemistry , biology , immunology , art , enzyme , histidine , humanities
The urocanic acid cis isomer ( cis ‐UCA) is a possible cutaneous photoreceptor for the immunomodulatory phenomena that follow ultraviolet B irradiation. Several experiments in animals show an inhibitory action of cis ‐UCA on cellular immunity. However, the action of cis ‐UCA on the synthesis of cytokines in keratinocytes remains unknown. Long‐term cultures of normal human keratinocytes were prepared in a serum‐free medium, and stimulated with 1 μg/ml of phorbol 12‐myristate 13‐acetate (TPA) and UCA or UVB‐UCA (10–100 μg/ml). Synthesis of the following cytokines was measured using ELISA and Northern blot techniques: TNF‐α, IL‐1α, IL‐1β, IL‐6, IL‐8 and TGF‐β1. TPA increased TNF‐α protein levels in culture supernatants. No changes in IL‐1α and IL‐1β protein levels were detected in basal culture supernatant after TPA stimulus. TPA augmented RNA expression for TNF‐α, IL‐1α, IL‐1β and TGF‐β1. UCA isomers did not induce cytokine changes in protein synthesis. Expression of IL‐1α and IL‐1β genes was increased after exposure to 100 μg/ml UVB‐UCA (70 μg/ml cis ‐UCA). A slight increase in TNF‐α RNA expression was detected when the dose of UVB‐UCA reached 100 μg/ml. No effects on cytokine synthesis were found after UCA stimulus. These results suggest that low doses of cis ‐UCA do not effect cytokine synthesis by keratinocytes.