RT Journal Article SR Electronic T1 Nicotinic Acid-Induced Flushing Is Mediated by Activation of Epidermal Langerhans Cells JF Molecular Pharmacology JO Mol Pharmacol FD American Society for Pharmacology and Experimental Therapeutics SP 1844 OP 1849 DO 10.1124/mol.106.030833 VO 70 IS 6 A1 Zoltán Benyó A1 Andreas Gille A1 Clare L. Bennett A1 Björn E. Clausen A1 Stefan Offermanns YR 2006 UL http://molpharm.aspetjournals.org/content/70/6/1844.abstract AB The antidyslipidemic drug nicotinic acid (niacin) has been used for decades. One of the major problems of the therapeutical use of nicotinic acid is a strong cutaneous vasodilation called flushing, which develops in almost every patient taking nicotinic acid. Nicotinic acid-induced flushing has been shown to be mediated by the nicotinic acid receptor GPR109A and to involve the formation of vasodilatory prostanoids. However, the cellular mechanisms underlying this short-term effect are unknown. Here, we show that epidermal Langerhans cells are essential for the cutaneous flushing response induced by nicotinic acid. Langerhans cells respond with an increase in [Ca2+]i to nicotinic acid and express prostanoid synthases required for the formation of the vasodilatory prostanoids prostaglandin E2 and prostaglandin D2. Depletion of epidermal Langerhans cells but not of macrophages or dendritic cells abrogates nicotinic acid-induced flushing. These data unexpectedly identify epidermal Langerhans cells as essential mediators of nicotinic acid-induced flushing and may help to generate new strategies to suppress the unwanted effects of nicotinic acid. In addition, our results suggest that Langerhans cells besides their immunological roles are also involved in the local regulation of dermal blood flow. The American Society for Pharmacology and Experimental Therapeutics