Exposure of skin to excessive ultraviolet-B (UVB) radiation causes epidermal hyperproliferation that leads to epidermal hyperplasia, however, it is not yet clear exactly how these responses progress.
We attempted to clarify the response patterns involved with epidermal hyperproliferation following UVB radiation.
UVB was irradiated at 2 minimal erythema doses (MED) to human back skin and epidermal morphologic changes were evaluated using in vivo confocal laser microscopy. Skin biopsy specimens were collected from exposed and from non-exposed regions, and were subjected to histochemical and immunohistochemical analysis.
The in vivo confocal laser microscopic analysis showed that UVB-induced epidermal hyperplasia was prominent at the epidermal rete ridges. Further, 3 days after UVB exposure, numerous Ki67-positive epidermal cells were observed in the epidermal rete ridges, but not in the epidermis at the top of the dermal papilla. These results suggest that cells highly responsive to UVB exist in the epidermal rete ridges and that their hyperproliferation leads to elongation of the epidermal rete ridges. In contrast, the number of keratin 10-positive basal cells, known as transitional cells, was increased throughout the epidermis, suggesting that an upward migration of keratinocytes from the epidermal basal layer occurred regardless of their location. However, diffusion of melanin to the suprabasal layers was markedly observed in epidermal regions above the dermal papillae, suggesting the occurrence of strong upper cell movement at this position.
Based on our results, we conclude that differences in keratinocyte responses to UVB radiation exist in cells located in the undulating epidermal basal layer.
To read this article in full you will need to make a payment
Purchase one-time access:Academic & Personal: 24 hour online accessCorporate R&D Professionals: 24 hour online access
One-time access price info
- For academic or personal research use, select 'Academic and Personal'
- For corporate R&D use, select 'Corporate R&D Professionals'
Subscribe:Subscribe to Journal of Dermatological Science
Already a print subscriber? Claim online access
Already an online subscriber? Sign in
Register: Create an account
Institutional Access: Sign in to ScienceDirect
- Heterogeneity of keratinocytes in the epidermal basal cell layer.J Cutan Pathol. 1990; 17: 129-143
- The heterogeneity of the germinative compartment in human epidermis and its implications in pathogenesis.Dermatology. 1994; 189: 340-343
- Keratinocyte stem cells: a commentary.J Invest Dermatol. 2002; 119: 888-899
- Flow cytometric identification of proliferative subpopulations within normal human epidermis and the localization of the primary hyperproliferative population in psoriasis.J Exp Med. 1993; 178: 1271-1281
- Epidermal remodelling in psoriasis.Br J Dermatol. 1996; 135: 433-438
- UVB-induced alterations in permeability barrier function: roles for epidermal hyperproliferation and thymocyte-mediated response.J Invest Dermatol. 1997; 108: 769-775
- Acute effects of UVB radiation on the proliferation and differentiation of keratinocytes.Photoderm Photoimmunol Photomed. 2002; 18: 253-261
- The immunohistochemical effects of a single challenge with an intermediate dose of ultraviolet B on normal human skin.Arch Dermatol Res. 1996; 288: 510-516
- In vivo confocal scanning laser microscopy of human skin: melanin provides strong contrast.J Invest Dermatol. 1995; 104: 946-952
- Growth fraction in breast cancers determined in situ with monoclonal antibody Ki-67.J Clin Pathol. 1986; 39: 977-980
- Onset of epidermal differentiation in rapidly proliferating basal keratinocytes.J Invest Dermatol. 1986; 87: 472-476
- Sequential expression of mRNA-encoded keratin sets in neonatal mouse epidermis: basal cells with properties of terminally differentiating cells.Cell. 1984; 37: 159-170
- The control of epidermal thickness.Br J Dermatol. 1972; 87: 187-199
- Relationship of cell formation and cell migration in the renewal of stratified squamous epithelia.Adv Biol Skin. 1964; V: 39-67
- Evidence that the centrally and peripherally located cells in the murine epidermal proliferative unit are two distinct cell populations.J Invest Dermatol. 1985; 84: 277-281
- Stem cells: attributes, cycles, spirals, pitfalls and uncertainties. Lessons for and from crypt.Development. 1990; 110: 1001-1020
- Stem cell patterning and fate in human epidermis.Cell. 1995; 80: 83-93
- Strategies of epithelial repair: modulation of stem cell and transit amplifying cell proliferation.J Cell Sci. 1998; 111: 2867-2875
- The epidermal proliferative unit: the possible role of the central basal cell.Cell Tissue Kinet. 1974; 7: 77-88
- The spatial relationship between stem cells and their progeny in the basal layer of human epidermis: a new view based on whole-mount labelling and lineage analysis.Development. 1999; 126: 2409-2418
- Heterogeneity in epidermal basal cell keratinocytes: morphological and functional correlations.Science. 1982; 215: 1239-1241
- Epidermal stem cells.J Invest Dermatol. 1983; 81: 121s-127s
- Separation of human epidermal stem cells from transit amplifying cells on the basis of differences in integrin function and expression.Cell. 1993; 73: 713-724
Accepted: December 21, 2004
Received in revised form: December 13, 2004
Received: August 11, 2004
© 2004 Japanese Society for Investigative Dermatology. Published by Elsevier Inc. All rights reserved.