Clement, Cristina C.; D'Alessandro, Angelo; Thangaswamy, Sangeetha; Chalmers, Samantha; Furtado, Raquel; Spada, Sheila; Mondanelli, Giada; Ianni, Federica; Gehrke, Sarah; Gargaro, Marco; Manni, Giorgia; Lopez Cara, Luisa Carlota; Runge, Peter; Tsai, Wanxia Li; Karaman, Sinem; Arasa, Jorge; Fernandez-Rodriguez, Ruben; Beck, Amanda; Macchiarulo, Antonio; Gadina, Massimo; Halin, Cornelia; Fallarino, Francesca; Skobe, Mihaela; Veldhoen, Marc; Moretti, Simone; Formenti, Silvia; Demaria, Sandra; Soni, Rajesh K.; Galarini, Roberta; Sardella, Roccaldo; Lauvau, Gregoire; Putterman, Chaim; Alitalo, Kari; Grohmann, Ursula; Santambrogio, Laura
(2021)
Tryptophan catabolism is a major metabolic pathway utilized by several professional and non-professional antigen presenting cells to maintain immunological tolerance. Here we report that 3-hydroxy-l-kynurenamine (3-HKA) is a biogenic amine produced via an alternative pathway of tryptophan metabolism. In vitro, 3-HKA has an anti-inflammatory profile by inhibiting the IFN-gamma mediated STAT1/NF-kappa Beta pathway in both mouse and human dendritic cells (DCs) with a consequent decrease in the release of pro-inflammatory chemokines and cytokines, most notably TNF, IL-6, and IL12p70. 3-HKA has protective effects in an experimental mouse model of psoriasis by decreasing skin thickness, erythema, scaling and fissuring, reducing TNF, IL-1 beta, IFN-gamma, and IL-17 production, and inhibiting generation of effector CD8(+) T cells. Similarly, in a mouse model of nephrotoxic nephritis, besides reducing inflammatory cytokines, 3-HKA improves proteinuria and serum urea nitrogen, overall ameliorating immune-mediated glomerulonephritis and renal dysfunction. Overall, we propose that this biogenic amine is a crucial component of tryptophan-mediated immune tolerance. 3-hydroxy-L-kynurenamine (3-HKA) is a metabolite deriving from a lateral pathway of tryptophan catabolism. Here the authors identify 3-HKA as a biogenic amine and show it has anti-inflammatory properties that can protect mice against psoriasis and nephrotoxic nephritis.