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World J Gastroenterol. Feb 28, 2018; 24(8): 877-881
Published online Feb 28, 2018. doi: 10.3748/wjg.v24.i8.877
Regulation of the intestinal immune system by flavonoids and its utility in chronic inflammatory bowel disease
Harald Peter Hoensch, Benno Weigmann
Harald Peter Hoensch, Private Practice Gastroenterology, Marien hospital, Darmstadt 64285, Germany
Benno Weigmann, Department of Medicine 1, University Medical Center, Erlangen 91052, Germany
Author contributions: Hoensch HP and Weigmann B contributed equally to this work, generated the figures and wrote the manuscript.
Conflict-of-interest statement: No potential conflicts of interest relevant to this article were reported.
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: Benno Weigmann, PhD, Senior Scientist, Department of Medicine 1, University Medical Center, Hartmann Str. 14, Erlangen D-91052, Germany.
Telephone: +49-9131-8535885 Fax: +49-9131-85355959
Received: October 25, 2017
Peer-review started: October 26, 2017
First decision: November 14, 2017
Revised: December 20, 2017
Accepted: December 27, 2017
Article in press: December 27, 2017
Published online: February 28, 2018

Flavonoids are phytochemicals which can regulate the activity of the intestinal immune system. In patients with chronic inflammatory bowel disease (IBD) there is an overexpression and imbalance of the components of the inflammatory immune reactions which are chronically activated. Suppression of inflammation can be achieved by anti-inflammatory drugs which are used in clinical medicine but these can cause serious side effects. Flavonoids can have natural immunosuppressive properties and inhibit the activation of immune cells and its effectors (chemokines, TNF-, cytokines). Phytochemicals such as flavonoids bind to the nuclear Ah (aryl hydrocarbon) -receptor thereby stimulating protective enzyme activities. As shown by clinical evidence in patients and by experimental work some flavonoids (apigenin, epigallocatechin gallate) were effective in the inhibition of inflammation. Instead of or additionally to anti-inflammatory drugs flavonoids can be used in IBD patients to treat the over-reactive immunologic system. This is accomplished by upregulation of the Ah-receptor. Flavonoids interact with toll-like receptors expressing on the surface of immune cells, then they were internalized to the cytosol and transferred into the nucleus, where they were attached to the Ah-receptor. The Ah-receptor binds to the Ah-R nuclear translocator and via Ah response element beneficial protective enzymes and cytokines are induced, leading to upregulation of the anti-inflammatory system.

Keywords: Flavonoids, Inflammatory bowel disease, Ah-receptor

Core tip: Overview regulation of the intestinal immune system by flavonoids and its utility in chronic inflammatory bowel disease.