Rácz E, Prens EP, Kant M, Florencia E, Jaspers NG, Laman JD, de Ridder D, van der Fits L. Narrowband ultraviolet B inhibits innate cytosolic double-stranded RNA receptors in psoriatic skin and keratinocytes.
Br J Dermatol 2011;
164:838-47. [PMID:
21143460 DOI:
10.1111/j.1365-2133.2010.10169.x]
[Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
BACKGROUND
The mode of action of narrowband ultraviolet B (NB-UVB) therapy in clearing psoriasis is incompletely understood, and in vivo studies at the molecular level in patients undergoing NB-UVB therapy are limited. We previously demonstrated increased expression and activity of double-stranded RNA (dsRNA) receptors in psoriasis lesions, and suggested that this enhanced innate signalling contributed to the maintenance of psoriatic inflammation.
OBJECTIVES
We investigated whether NB-UVB affects dsRNA receptor expression and function in vivo as well as in vitro.
METHODS
Skin samples of patients with psoriasis undergoing NB-UVB treatment were analysed for epidermal messenger RNA (mRNA) expression of the various dsRNA receptors by microarray and quantitative reverse transcription-polymerase chain reaction. Primary human keratinocytes were irradiated with NB-UVB and stimulated with interferon (IFN)-α or IFN-γ, critical cytokines in psoriasis. The dsRNA analogue polyriboinosinic-polyribocytidylic acid was used to assess the functional responsiveness of the cells to dsRNA.
RESULTS
NB-UVB therapy of patients with psoriasis resulted in a significantly reduced mRNA expression of the activating dsRNA receptors MDA5 (IFIH1) and RIG-I (DDX58). On the other hand, expression of LGP2 (DHX58), toll-like receptor 3 (TLR3) and PKR (EIF2AK2) was not affected. In vitro, NB-UVB irradiation completely blocked the upregulation of four of the dsRNA receptors in primary human keratinocytes stimulated with IFN-α or IFN-γ, resulting in an attenuated inflammatory response to dsRNA.
CONCLUSIONS
Our results show that NB-UVB irradiation inhibits the local innate inflammatory response to dsRNA, and suggest a novel mechanism of action of NB-UVB phototherapy in psoriasis.
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