1. ¹Department of Dermatology and Venerology, J.W. Goethe-University, Frankfurt/Main, Germany
2. ²Phenion GmbH & Co., Frankfurt/Main, Germany
3. ³Kinematic Cell Research Group, Biocentre, J.W. Goethe-University, Frankfurt/Main, Germany

Correspondence: Dr Stefan Kippenberger, Department of Dermatology and Venerology, J.W. Goethe-University, Theodor-Stern-Kai 7, Frankfurt 60590, Germany. E-mail: kippenberger@em.uni-frankfurt.de

⁴These authors contributed equally to this work

Received 2 June 2006; Revised 25 August 2006; Accepted 12 September 2006; Published online 30 November 2006.

Abstract

DNA codes for genetic information. Furthermore, recent findings suggest that DNA offers additional function, particularly in the recognition of microorganisms. In this study, we investigated two classes of oligodeoxynucleotides (ODN) in skin keratinocytes; namely, an ODN comprising two cytidine-phosphate-guanosine (CpG) motifs (CpG-1-phosphorothioate (PTO)) and a poly-cytidine (Non-CpG-5-PTO) as control. Both fluorescence-tagged ODN were rapidly taken up by cells and accumulated already after 5 minutes in perinuclear compartments. In order to test whether ODN convey immunological effects in keratinocytes, secretion of IL-8 was measured. Interestingly, both CpG-1-PTO and Non-CpG-5-PTO suppressed basal and tumor necrosis factor -induced IL-8 levels measured in cell culture supernatants. Experiments using deletion mutant revealed a critical length of approximately 16 nucleotides conveying IL-8 suppression. Studies regarding the ODN backbone offered that PTO bondings are critical for significant IL-8 suppression. In order to substantiate the anti-inflammatory response, a contact hypersensitivity mouse model was utilized. Topical application of Non-CpG-5-PTO-containing ointments reduced ear thickness in sensitized mice. Taken together, these findings suggest an anti-inflammatory effect of ODN in epithelial cells in vitro and in vivo, indicating that DNA molecules offer distinct biological activities restricted to the physiological compartment applied. This effect seems to be independent from Toll-like receptor 9.