Emerging role for kynurenines in metabolic pathologies

Purpose of review So far, the tryptophan catabolites generated in the kynurenine pathway have been mainly studied in relation to oncologic and mental health disorders. The current review provides an update on the emerging biomedical interest for kynurenine pathway activity in the field of energy homeostasis and metabolic diseases. Recent findings Kynurenine pathway enzymes are expressed in tissues relevant for energy homeostasis such as fat, skeletal muscle, liver and endocrine pancreas, blood vessel and heart, and are regulated by nutritional and inflammatory signals. Kynurenine pathway metabolites have been proposed as biomarkers for initiation and progression of atherosclerosis and diabetes. Exercise training activation of kynurenine pathway in skeletal muscles increases lipid metabolism and thermogenesis, and it limits weight gain, inflammation, insulin resistance, and glucose intolerance in rodents fed a high-fat diet. Manipulation of kynurenine pathway metabolism through administration of enzyme inhibitors or kynurenine pathway metabolites can serve as novel therapeutic strategy for atherosclerosis, obesity, glucose intolerance, or impaired insulin secretion. Summary Although we are far from a complete understanding of the role of kynurenine pathway in the modulation of energy homeostasis, targeting kynurenine pathway harbors high potential to expand the range of therapies to prevent and treat metabolic diseases.