PR000830 (Project)

Description:Trisomy 21 (T21) causes Down syndrome (DS), affecting immune and neurological function by unknown mechanisms. We report here a large metabolomics study of plasma and cerebrospinal fluid showing that people with DS produce elevated levels of kynurenine and quinolinic acid, two tryptophan catabolites with potent immunosuppressive and neurotoxic properties, respectively. We demonstrate that immune cells of people with DS overexpress IDO1, the rate-limiting enzyme in the kynurenine pathway (KP) and a known interferon (IFN)-stimulated gene. Furthermore, we show positive correlations among levels of IFN-inducible cytokines and KP dysregulation. Using metabolic tracing assays, we determine that IFN stimulation causes IDO1 overexpression and kynurenine overproduction in cells with T21, dependent on overexpression of IFN receptors encoded on chromosome 21. Finally, we show a mouse model of DS carrying triplication of the IFN receptors exhibits KP dysregulation. Altogether, these results reveal a mechanism by which T21 could drive immunosuppression and neurotoxicity in DS.