IN VIVO PHOTOINDUCTION OF METALLOTHIONEIN IN HUMAN SKIN BY ULTRAVIOLET IRRADIATION

✍ Scribed by ANSTEY, ALEXANDER; MARKS, RONALD; LONG, COLIN; NAVABI, HOSSEIN; PEARSE, ANTHONY; WYNFORD-THOMAS, DAVID; JASANI, BHARAT

• Publisher: John Wiley and Sons
• Year: 1996
• Tongue: English
• Weight: 573 KB
• Volume: 178
• Category: Article
• ISSN: 0022-3417
• DOI: 10.1002/(sici)1096-9896(199601)178:1<84::aid-path430>3.0.co;2-w

✦ Synopsis

The aims of this study were to confirm and substantiate the in vivo cutaneous induction of metallothionein (MT) in human skin by UVR, which we have reported in brief previously, and to make a preliminary attempt to characterize the time course of this phenomenon. Buttock skin in 32 volunteers was irradiated with 2 M E D of UVB and biopsies were taken a t 24 h from matched non-irradiated and irradiated sites. In the kinetic study, skin biopsies from six volunteers were taken a t 0, 2, 8, 24, and 48 h after 2 M E D UVB irradiation. M T was immunolocalized in formalin-fixed, paraffin-embedded tissue with the monoclonal antibody E9 by an indirect immunoperoxidase method. Statistically significant differences between immunocytochemical scores were identified between non-irradiated (NI) and irradiated (I) skin within suprabasal keratinocytes (mean: NI=1-2, I=5.1; P=O*Ol), superficial dermal fibroblasts (mean: NI=2, I=43; P<O.OOl), mid-dermal fibroblasts (mean: NI=O, I=27; P<O.OOl), and deep dermal fibroblasts (mean: NI=O, I = l l ; P<O.OOl). In the kinetic study, no consistent rise in M T score with time was observed for the epidermal component. In dermal fibroblasts, however, the first statistically significant rise in immunocytochemically detectable MT was detected at 2 h and this was found to plateau beyond 8 h. These results confirm that ambient levels of UV irradiation are capable of inducing MT in human skin in vivo. Taken together with the relative rapidity of the response, this suggests a physiological photoprotective role for MT in human skin cells. The lack of a kinetic increase in epidermal M T may be due to high basal levels. Induction of M T in dermal fibroblasts may reflect the effects of a diffusible factor released from keratinocytes after UVR.