BACKGROUND An increase of plasma kynurenine concentrations, potentially bioactive metabolites of tryptophan, was found in subjects with obesity, resulting from low-grade inflammation of the white adipose tissue. Bariatric surgery decreases low-grade inflammation associated with obesity and improves glucose control. OBJECTIVE Our goal was to determine the concentrations of all kynurenine metab...

Substantial increases in the tryptophan-kynurenine pathway metabolites, l-kynurenine and the neurotoxin quinolinic acid, occur in human brain, blood and systemic tissues during immune activation. Studies in vitro have shown that not all human cells are capable of synthesizing quinolinate. To investigate further the mechanisms that limit l-kynurenine and quinolinate production, the activities of...

BACKGROUND Tryptophan is an essential amino acid for the synthesis of proteins and important metabolites such as serotonin, melatonin, tryptamine and niacin. After protein synthesis, more than 90 % of tryptophan catabolism occurs along the kynurenine pathway. The inflammation-inducible enzyme indoleamine 2,3 dioxygenase (IDO) is responsible for the first rate-limiting step in the kynurenine pat...

An adaptive increase in tryptophan pyrrolase activity was obtained in the cell-free extracts of Drosophila melanogaster larvae which were given a dietary supplement of L-tryptophan. This activity was detectable in the extracts prepared from larval fatbodies when these were isolated from the remaining body tissues, but the present methods did not reveal any activity in extracts from the latter. ...

The kynurenine pathway is a fundamental mechanism of immunosuppression and peripheral tolerance. It is increasingly recognized as playing a major role in the pathogenesis of a wide variety of inflammatory, neurodegenerative and malignant disorders. However, the temporal dynamics of kynurenine pathway activation and metabolite production in human immune cells is currently unknown. Here we report...

The kynurenine pathway of tryptophan degradation is hypothesized to play an important role in Huntington disease, a neurodegenerative disorder caused by a polyglutamine expansion in the protein huntingtin. Neurotoxic metabolites of the kynurenine pathway, generated in microglia and macrophages, are present at increased levels in the brains of patients and mouse models during early stages of dis...

As part of a study of kynurenine metabolism in Neurospora crassa, the enzyme, kynureninase, has been investigated. Evidence from studies with mycelial pads suggests that tryptophan gives rise to kynurenine, which may be degraded to anthranilic acid (1). Kynurenine is also oxidized to hydroxykynurenine, which is converted to hydroxyanthranilic acid (2). The similarity of these reactions, i.e. th...

Marked increases in metabolites of the L-tryptophan-kynurenine pathway, L-kynurenine and quinolinic acid (Quin), were observed in serum and cerebrospinal fluid (CSF) of both the rat and human with renal insufficiency. The mechanisms responsible for their accumulation after renal insufficiency were investigated. In patients with chronic renal insufficiency, elevated levels of serum L-kynurenine ...

PURPOSE Posttranslational modification by UV filters is a key event in human lenses that appears to be largely responsible for normal age-dependent yellowing. It has been proposed that subsequent reactions of these covalently bound UV filters may also be involved in the genesis of age-related nuclear cataract. To examine this hypothesis, the levels of kynurenine-lysine and kynurenine-histidine ...

Tryptophan degradation in mice initiated by indoleamine 2,3-dioxygenase was characterized, taking advantage of its induction by bacterial lipopolysaccharide. Our results demonstrated that in various tissues, N-formylkynurenine produced by the dioxygenase from tryptophan was rapidly hydrolyzed into kynurenine by a kynurenine formamidase, but it was not further metabolized. The localization in th...