Reverse signaling through GITR ligand enables dexamethasone to activate IDO in allergy.

Department of Experimental Medicine and Biochemical Sciences, University of Perugia, 06126 Perugia, Italy.

Nature medicine 2007 May

filter terms:

Glucocorticoid-induced tumor necrosis factor receptor (GITR) on T cells and its natural ligand, GITRL, on accessory cells contribute to the control of immune homeostasis. Here we show that reverse signaling through GITRL after engagement by soluble GITR initiates the immunoregulatory pathway of tryptophan catabolism in mouse plasmacytoid dendritic cells, by means of noncanonical NF-kappaB-dependent induction of indoleamine 2,3-dioxygenase (IDO). The synthetic glucocorticoid dexamethasone administered in vivo activated IDO through the symmetric induction of GITR in CD4(+) T cells and GITRL in plasmacytoid dendritic cells. The drug exerted IDO-dependent protection in a model of allergic airway inflammation. Modulation of tryptophan catabolism via the GITR-GITRL coreceptor system might represent an effective therapeutic target in immune regulation. Induction of IDO could be an important mechanism underlying the anti-inflammatory action of corticosteroids.

Citation

Ursula Grohmann, Claudia Volpi, Francesca Fallarino, Silvia Bozza, Roberta Bianchi, Carmine Vacca, Ciriana Orabona, Maria L Belladonna, Emira Ayroldi, Giuseppe Nocentini, Louis Boon, Francesco Bistoni, Maria C Fioretti, Luigina Romani, Carlo Riccardi, Paolo Puccetti. Reverse signaling through GITR ligand enables dexamethasone to activate IDO in allergy. Nature medicine. 2007 May;13(5):579-86