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UVB Induces IL‐12 Transcription in Human Keratinocytes in vivo and in vitro
Author(s) -
Enk Claes D.,
Mahanty Siddhartha,
Blauvelt Andrew,
Katz Stephen I.
Publication year - 1996
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1996.tb09642.x
Subject(s) - trypsinization , epidermis (zoology) , biology , immune system , cytokine , keratinocyte , tumor necrosis factor alpha , population , interleukin 20 , in vitro , in vivo , microbiology and biotechnology , interleukin , immunology , interleukin 5 , medicine , biochemistry , enzyme , trypsin , environmental health , anatomy
Human epidermal cells produce a wide range of cytokines, including those characteristic of Th2‐like responses such as interleukin (IL)‐4 and IL‐10. As well, keratinocytes have recently been shown to produce Th1‐like cytokines such as IL‐12. Exposure to UVB has profound effects on the skin and systemic immune system, which is in part mediated by secretion of tumor necrosis factor (TNF)‐α by epidermal cells. Because IL‐12 induces production of TNF‐α by certain cells of the immune system, we sought to determine whether UVB is an inducer of IL‐12 gene expression in epidermal cells. Human epidermal cells were exposed to UVB radiation in vivo , isolated by suction blister technique and trypsinization and transcription of the IL‐12 p35 and p40 chains was examined by RT‐PCR. We found the p35 chain of IL‐12 to be constitutively expressed and the p40 chain inducible by UVB irradiation. Because epidermis consists of a heterogenous cell population with distinct cytokine repertoires, we sought to determine the cellular source of the IL‐12 message after UVB exposure. After depleting UVB‐exposed epidermal cells for DR + cells, no reduction in the IL‐12 activity was detected, suggesting that keratinocytes are a source of IL‐12 transcripts in UVB‐exposed human epidermis. This was supported by the up‐regulation of IL‐12 p40 transcripts in UV‐irradiated cultured keratinocytes that were devoid of DR + cells. Up‐regulation of IL‐12 p40 gene expression by UVB as demonstrated here, taken together with the finding that keratinocytes also up‐regulate IL‐10 transcription, suggests that there is a complex interplay between Th1‐and Th2‐like epidermisderived cytokines following exposure to UVB.