ISSN:
1600-0625
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Medicine
Notes:
UVB irradiation of cultured human keratinocytes induces both the conversion of 7-dehydrocholesterol (7-DHC) to calcitriol (1α,25(OH)2D3) and the release of tumor necrosis factor-a (TNF-α) in these cells. Calcitriol synthesis in human keratinocytes was reduced in the presence of a neutralizing polyclonal antibody directed against human TNF-α. On the other hand, we found a 1.7-fold higher stimulatory effect of UVB on liberation of TNF-α in cultured keratinocytes enriched with 7-DHC compared with irradiated cell cultures in absence of 7-DHC. These observations argue in favor of a synergetic relationship between generation of TNF-α and calcitriol in UVB irradiated keratinocytes. In addition, we found that TNF-α potently increases the conversion rate of vitamin D3(cholecalciferol) to calcitriol this cell system. The UVB-triggered formation of both TNF-α and calcitriol in cultured keratinocytes as wavelength-, time- and dose-dependent. Maximum formation of TNF-α and calcitriol was found at 300 nm and UVB doses of 30 mJ/cm2. The enhancement of both, the formation of TNF-α and calcitriol in keratinocytes by UVB may be of relevance for regulation of growth and apoptosis in light-exposed epidermal cells and, in addition, may play a role in the UVB treatment of deseased skin, including psoriasis.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.0906-6705.2005.0266d.x
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