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Mediators of Inflammation
Volume 2013 (2013), Article ID 391984, 9 pages
Review Article

Remarkable Role of Indoleamine 2,3-Dioxygenase and Tryptophan Metabolites in Infectious Diseases: Potential Role in Macrophage-Mediated Inflammatory Diseases

1Human Health Sciences, Graduate School of Medicine and Faculty of Medicine, Kyoto University, 53 Kawahara-cho, Shogoin, Sakyo-Ku, Kyoto 606-8507, Japan
2Faculty of Health Science, Suzuka University of Medical Science, Suzuka, Mie, Tsu 510-0293, Japan

Received 12 October 2012; Revised 28 December 2012; Accepted 3 January 2013

Academic Editor: Chiou-Feng Lin

Copyright © 2013 Yuki Murakami et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Indoleamine 2,3-dioxygenase 1 (IDO1), the L-tryptophan-degrading enzyme, plays a key role in the immunomodulatory effects on several types of immune cells. Originally known for its regulatory function during pregnancy and chronic inflammation in tumorigenesis, the activity of IDO1 seems to modify the inflammatory state of infectious diseases. The pathophysiologic activity of L-tryptophan metabolites, kynurenines, is well recognized. Therefore, an understanding of the regulation of IDO1 and the subsequent biochemical reactions is essential for the design of therapeutic strategies in certain immune diseases. In this paper, current knowledge about the role of IDO1 and its metabolites during various infectious diseases is presented. Particularly, the regulation of type I interferons (IFNs) production via IDO1 in virus infection is discussed. This paper offers insights into new therapeutic strategies in the modulation of viral infection and several immune-related disorders.