title: Effect of Repeated Daily Dosing with 2,4-Dinitrochlorobenzene on Glutathione Biosynthesis and Nrf2 Activation in Reconstructed Human Epidermis.
abstract: Glutathione (GSH) plays a major role in skin detoxification processes due to its ability to conjugate electrophilic exogenous compounds with, and sometimes without, catalysis by glutathione-s-transferase (GST). GST activity has been demonstrated both in skin and in most in vitro skin equivalents but so far studies have focussed on chemical clearance (conjugate identification and rate of conjugation) and did not consider the GSH lifecycle (conjugation, recycling, synthesis). We used the model skin sensitizer 2,4-dinitrochlorobenzene (DNCB) to investigate the effects of chemical exposure on GSH lifecycle in reconstructed human epidermis (RHE). We demonstrated that the RHE model is suitable to carry out repeated cycles of 2-h exposure to DNCB over a 3-day period. After each exposure to DNCB, the level of GSH is diminished in a dose dependent manner. After a 22-h recovery period, GSH is replenished back to initial levels. Accumulation of the nuclear factor E2-related factor 2 (Nrf2) in the cytosol also occurs within the 2 h of exposure to DNCB but returns to baseline during each recovery period, demonstrating that activation of the Nrf2 signaling pathway offers a rapid response to chemical stress. The amount of dinitrophenyl-glutathione (DNP-SG) formed with DNCB (1) increased between the first and second exposure and (2) reached a plateau between the second and third exposure. Collectively, these data suggest that the metabolic capacity of skin may not be fixed in time but defence mechanisms might be activated in response to exposure to exogenous compounds, resulting in their accelerated clearance.
authors: *Unilever, Safety and Environmental Assurance Centre, Colworth Science Park, Sharnbrook, Bedfordshire MK44 1LQ, UK; sandrine.spriggs@unilever.com.
authors: Sandrine
authors: S
authors: Spriggs
authors: *Unilever, Safety and Environmental Assurance Centre, Colworth Science Park, Sharnbrook, Bedfordshire MK44 1LQ, UK.
authors: David
authors: D
authors: Sheffield
authors: Department of Molecular and Clinical Pharmacology, MRC Centre for Drug Safety Science, the University of Liverpool, Sherrington Building, Ashton Street, Liverpool L69 3GE, UK.
authors: Adedamola
authors: A
authors: Olayanju
authors: Department of Molecular and Clinical Pharmacology, MRC Centre for Drug Safety Science, the University of Liverpool, Sherrington Building, Ashton Street, Liverpool L69 3GE, UK.
authors: Neil R
authors: NR
authors: Kitteringham
authors: Department of Molecular and Clinical Pharmacology, MRC Centre for Drug Safety Science, the University of Liverpool, Sherrington Building, Ashton Street, Liverpool L69 3GE, UK.
authors: Dean J
authors: DJ
authors: Naisbitt
authors: *Unilever, Safety and Environmental Assurance Centre, Colworth Science Park, Sharnbrook, Bedfordshire MK44 1LQ, UK.
authors: Maja
authors: M
authors: Aleksic
mesh_terms: D004137:Dinitrochlorobenzene / Q000633:toxicity*; D004817:Epidermis / Q000187:drug effects*; D005978:Glutathione / Q000096:biosynthesis*; D006801:Humans; D051267:NF-E2-Related Factor 2 / Q000378:metabolism*; D046509:Tissue Culture Techniques
chemical_list: D004137:Dinitrochlorobenzene; D051267:NF-E2-Related Factor 2; C495635:NFE2L2 protein, human; D005978:Glutathione
keywords: glutathione conjugation; in vitro skin models; reconstructed human epidermis; repeated dosing; skin metabolism; skin sensitizers