Funding sources Section for Climate Therapy, Department of Rheumatology, Oslo University Hospital, Oslo, Norway; The Norwegian Psoriasis Association.
CLINICAL AND LABORATORY INVESTIGATIONS
Sun exposure rapidly reduces plasmacytoid dendritic cells and inflammatory dermal dendritic cells in psoriatic skin
Article first published online: 27 SEP 2011
© 2011 The Authors. BJD © 2011 British Association of Dermatologists
British Journal of Dermatology
Volume 165, Issue 4, pages 792–801, October 2011
How to Cite
Heier, I., Søyland, E., Krogstad, A.-L., Rodríguez-Gallego, C., Nenseter, M.S. and Jahnsen, F.L. (2011), Sun exposure rapidly reduces plasmacytoid dendritic cells and inflammatory dermal dendritic cells in psoriatic skin. British Journal of Dermatology, 165: 792–801. doi: 10.1111/j.1365-2133.2011.10430.x
Conflicts of interest All the authors declare that they have no conflict of interest.
- Issue published online: 27 SEP 2011
- Article first published online: 27 SEP 2011
- Accepted manuscript online: 28 MAY 2011 10:23AM EST
- Accepted for publication 12 May 2011
Background Interferon (IFN)-α-producing plasmacytoid dendritic cells (pDCs), inflammatory CD11c+CD1c− myeloid dendritic cells (mDCs) and macrophages have been found to contribute to the pathogenesis of psoriasis. Heliotherapy is a well-established treatment modality of this disease, although the details of how the effects are mediated are unknown.
Objectives To test the hypothesis that exposure to natural sun affects pathogenic DC subsets in lesional skin.
Methods Skin biopsies were obtained from lesional and nonlesional skin in 10 patients with moderate to severe psoriasis subjected to controlled sun exposure on Gran Canaria. Biopsies were obtained at baseline, day 2 and day 16 and examined by immunohistochemistry.
Results Sixteen days of heliotherapy had excellent clinical effect on patients with psoriasis, with significant reductions in Psoriasis Area and Severity Index (PASI) scores. In lesional skin pDC numbers and expression of MxA, a surrogate marker for IFN-α, were rapidly reduced. Inflammatory CD11c+CD1c− mDCs were significantly reduced whereas resident dermal CD11c+CD1c+ mDCs were unaffected. Expression levels of the maturation marker DC-LAMP (CD208) on mDCs were significantly reduced after sun exposure, as were the numbers of lesional dermal macrophages. A decrease of dermal DC subsets and macrophages was already observed after 1 day of sun exposure. An additional finding was that DC-SIGN (CD209) is primarily expressed on CD163+ macrophages and not DCs.
Conclusions The clinical improvement in psoriasis following sun exposure is associated with rapid changes in dermal DC populations and macrophages in lesional skin, preceding the clinical effect. These findings support the concept that these DC subsets are involved in the pathogenesis of psoriasis and suggest that sun-induced clinical benefit may partly be explained by its effect on dermal DCs.