The kynurenine system and immunoregulation.

Abstract

There is developing interest in the role of the kynurenines in the immune function. A considerable amount of evidence has accumulated as concerns interactions between the kynurenine pathway, cytokines and the nervous system. Indoleamine 2,3-dioxygenase (IDO) occupies a key position connecting the immune system and the kynurenine pathway. There are evidences of the immunosuppressive effect of IDO. Following the interferon (IFN)-mediated activation of antigen presenting cells, the induction of IDO and the kynurenine system exerts a counter-regulating effect, maintaining the homeostasis. Inhibition of T cell functions, activation of the regulatory T cells, and the inhibition of Natural Killer cells are among the important factors in the immunosuppressive effects of IDO and kynurenines. There is a close connection between cytokines (IFN-α, IFN-γ, TNF-α, TGF-β, IL-4 and IL-23) and the kynurenine system, and an imbalance in the TH1/TH2 cytokine profile may possibly lead to neurologic or psychiatric disorders. As the tryptophan metabolic pathway is activated by pro-inflammatory stimuli, the anti-inflammatory effect of kynurenic acid provides a further feedback mechanism in modulating the immune responses.

• Authors: Yvette Mándi, László Vécsei
• Journal: Journal of neural transmission (Vienna, Austria : 1996) (J Neural Transm (Vienna)) Vol. 119 Issue 2 Pg. 197-209 (Feb 2012) ISSN: 1435-1463 [Electronic] Austria
• PMID: 21744051 (Publication Type: Journal Article, Review)

Chemical References

• Indoleamine-Pyrrole 2,3,-Dioxygenase
• Kynurenine

Topics

• Animals
• Humans
• Immune Tolerance (immunology)
• Immunomodulation (physiology)
• Indoleamine-Pyrrole 2,3,-Dioxygenase (physiology)
• Inflammation (enzymology, immunology, prevention & control)
• Kynurenine (metabolism, physiology, therapeutic use)
• Neural Pathways (enzymology, immunology, pathology)
• T-Lymphocytes, Regulatory (enzymology, immunology, pathology)