Tryptophan metabolism can modulate immunologic tolerance in primitive vertebrate lamprey via IDO-kynurenine-AHR pathway

Tryptophan and Cortisol Modulate the Kynurenine and Serotonin Transcriptional Pathway in the Kidney of Oncorhynchus kisutch

“…Some authors [48] indicated that tryptophan is metabolized via the kynurenine pathway (see Figure 1). However, this pathway has two sub-pathways after kynurenine appears in two potential ways, quinolinic acid and kynurenic acid, where the latter has a kynurenine aminotransferase 2 (KIAT 2) enzyme that metabolizes kynurenic acid.…”

“…Also, the IFNγ-stimulation of macrophages has been closely linked to inducing the mammalian macrophage IDO response [49]. Lampetra japonicum (lamprey) demonstrated that exogenous tryptophan could inhibit the expression of pro-inflammatory factors and promote the expression of anti-inflammatory factors by inhibiting the MyD88 signaling pathway and activating the IDO-KYN-AHR (aryl hydrocarbon receptor) signaling pathway [48]. In male BALB/c mice [50], exogenous kynurenic acid (KYNA) was indicated to have low levels of cytotoxicity toward murine splenocytes and exhibited immunotropic properties.…”

Recent Advances in Current Uptake Situation, Metabolic and Nutritional Characteristics, Health, and Safety of Dietary Tryptophan

“…34 In vertebrates, Trp is degraded mainly via the KP which is closely associated with neurology and depression. 35 In the brain, 36 Trp acts on neuronal N-methyl-D-aspartate (NMDA) receptors, and glutamate-activated postsynaptic calcium receptors via the KP metabolites QA and KA, which play an important role in learning and memory. KA acts as an NMDA receptor antagonist at the glycine binding site and is (1) 90% of the kynurenine pathway degradation occurs in the liver, where TPH is converted to kynurenine via TDO; the remaining kynurenine degradation occurs via IDO in the brain, gastrointestinal tract, and liver.…”

“…IBS, osteoarthritis (OA), and acute pancreatitis (AP) are the more typical inflammatory diseases related to Trp metabolism. In a study to explore the role of Trp in vertebrate immunity, Trp was shown to be nontoxic by cellular experiment, 35 where Trp entered leukocytes to be degraded via KP. Trp not only decreased the expression of proinflammatory factors Lj-TNF-α, Lj-IL-1β, and Lj-NF-κB, but also up-regulated the expression of anti-inflammatory factor Lj-TGF-β.…”

“…This regulation occurs through the production of KYN, which affects mucosal amino acid nutrition, mucosal immune response, and intestinal microbial community metabolism. , A study points out that during pregnancy, the placenta acts as a mother–infant barrier and channel where IDO and TDO expression and Trp levels can influence the level of offspring health . In vertebrates, Trp is degraded mainly via the KP which is closely associated with neurology and depression …”