Prospective Study
Copyright ©The Author(s) 2015. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Mar 28, 2015; 21(12): 3636-3643
Published online Mar 28, 2015. doi: 10.3748/wjg.v21.i12.3636
Helicobacter pylori and serum kynurenine-tryptophan ratio in patients with colorectal cancer
Ayse Basak Engin, Bensu Karahalil, Ali Esat Karakaya, Atilla Engin
Ayse Basak Engin, Bensu Karahalil, Ali Esat Karakaya, Department of Toxicology, Faculty of Pharmacy, Gazi University, TR 06330 Hipodrom, Ankara, Turkey
Atilla Engin, Department of General Surgery, Faculty of Medicine, Gazi University, TR 06500 Beşevler, Ankara, Turkey
Author contributions: Engin AB performed the majority of the experiments, designed the study and wrote the manuscript; Karahalil B and Karakaya AE edited the manuscript; and Engin A co-ordinated and provided the collection of human material, designed the study and edited the manuscript.
Ethics approval: The study was approved by Gazi University, Local Ethics Committee.
Informed consent: All participants’ rights were protected and informed consents were obtained according to the Helsinki Declaration.
Conflict-of-interest: Authors declare that there is no conflict of interest.
Data sharing: Participants gave informed consent for data sharing.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See:
Correspondence to: Ayse Basak Engin, PhD, Department of Toxicology, Faculty of Pharmacy, Gazi University, TR 06330 Hipodrom, Ankara, Turkey.
Telephone: +90-312-2023084 Fax: +90-312-2222326
Received: September 11, 2014
Peer-review started: September 12, 2014
First decision: October 29, 2014
Revised: December 1, 2014
Accepted: January 16, 2015
Article in press: January 16, 2015
Published online: March 28, 2015
Core Tip

Core tip: Persistent inflammation of the stomach induced by Helicobacter pylori (H. pylori) can have consequences on the rest of the body. Despite the vigorous innate and adaptive immune response against the bacterium, H. pylori escape and evade host responses by a variety of mechanisms. Low tryptophan levels and increased concentrations of its degradation product, kynurenine, may be directly involved in diminished T-cell responsiveness to antigenic stimulation in cancer. H. pylori seropositive colorectal cancer patients with significantly higher kynurenine/tryptophan and reduced nitric oxide suggested that H. pylori might support immune tolerance leading to cancer development, even in patients without an apparent upper gastrointestinal tract disease.