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Narrow-band UVB induces apoptosis in human keratinocytes

Paper ID Volume ID Publish Year Pages File Format Full-Text
31245 44577 2006 8 PDF Available
Title
Narrow-band UVB induces apoptosis in human keratinocytes
Abstract

Narrow-band ultraviolet (NB-UVB) phototherapy emits mostly 311/312 nm light and is commonly used in the treatment of inflammatory skin disorders. As a source of UVB irradiation, NB-UVB causes apoptosis in T lymphocytes but its effects on keratinocytes are unknown. Herein, we have investigated the ability of NB-UVB to induce apoptosis in keratinocytes. Two types of human keratinocytes, primary and immortalized, were exposed to NB-UVB and broad-band UVB (BB-UVB; 315–280 nm) and tested for apoptosis. Both UVB light sources induced apoptosis in keratinocytes as determined by the presence of DNA ladders, although NB-UVB required approximately ten fold higher doses; NB-UVB (1000 mJ/cm2) and BB-UVB (125 mJ/cm2). By comparison, lower doses of NB-UVB (750 mJ/cm2) induced apoptosis in T lymphocytes, suggesting cell type specificity for NB-UVB induced apoptosis. Approximately, 50% or more of the cells underwent apoptosis when exposed to NB-UVB or BB-UVB as revealed by TUNEL assay. Electron micrographs showed that NB-UVB irradiated keratinocytes contained marked chromatin condensation, extensive cytoplasmic vacuolization and fragmentation of the nuclear envelope. Furthermore, Western blot analysis confirmed the presence of activated products of caspase 3 in keratinocytes that received apoptotic doses of NB-UVB. This study defines conditions by which NB-UVB irradiation causes apoptosis in keratinocytes.

Keywords
Skin inflammatory disorders; Phototherapy; UVB damage; Narrow-band UVB
First Page Preview
Narrow-band UVB induces apoptosis in human keratinocytes
Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Photochemistry and Photobiology B: Biology - Volume 82, Issue 2, 1 February 2006, Pages 132–139
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering