• Masatsugu Kurokawa, Fumio Kokubu, Satoshi Matsukura, Mio Kawaguchi, Koushi Ieki, Shintarou Suzuki, Miho Odaka, Shin Watanabe, Hiroko Takeuchi, Tomoko Akabane, Kazuhito Asano, Michiko Iwase, Ikuo Honma, and Mitsuru Adachi.
• First Department of Internal Medicine, Showa University School of Medicine, Tokyo, Japan.
• Int. Arch. Allergy Immunol. 2005 Jan 1; 137 Suppl 1: 60-8.

BackgroundThymus and activation-regulated chemokine (TARC; CCL17) is a lymphocyte-directed CC chemokine that specifically attracts T-helper (Th) 2 cells positive for the CC chemokine receptor 4 (CCR4(+)). Corticosteroids reduce airway inflammation, as reflected by reduced numbers of eosinophils and T cells and reduced expression of cytokines. We investigated TARC production and the inhibitory effects of corticosteroids on TARC expression in a murine model of allergic asthma.MethodsBALB/c mice were sensitized by intraperitoneal injection of ovalbumin (OVA) with alum. Once daily for 1 week, mice received injections of dexamethasone or 0.2 ml saline (control), then 1 h later inhaled aerosolized 1% OVA for 30 min. Mice were killed 24 h after OVA challenge for bronchoalveolar lavage and lung tissue examination.ResultsTARC was expressed mainly in the bronchial epithelial cells. Dexamethasone attenuated OVA-induced airway eosinophilia, lymphocyte infiltration, and airway hyperresponsiveness. Dexamethasone also decreased TARC production in the bronchoalveolar lavage fluid and decreased expression of TARC mRNA and TARC protein in lung tissue.ConclusionsThe corticosteroid dexamethasone inhibits TARC production in a murine model of allergic asthma in vivo. The beneficial effect of corticosteroids in bronchial asthma is due in part to their direct inhibitory effects on TARC production.Copyright 2005 S. Karger AG, Basel.

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