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Copyright ©The Author(s) 2016. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Hepatol. Nov 18, 2016; 8(32): 1354-1369
Published online Nov 18, 2016. doi: 10.4254/wjh.v8.i32.1354
Toll-like receptors in pathophysiology of liver diseases
Safak Kiziltas
Safak Kiziltas, Department of Gastroenterology, Baskent University Istanbul Hospital, 34662 Istanbul, Turkey
Author contributions: Kiziltas S performed conception and design of the paper and drafting and revising the article and had primary responsibility for final content.
Conflict-of-interest statement: Author declares no conflict of interests for this article.
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: http://creativecommons.org/licenses/by-nc/4.0/
Correspondence to: Safak Kiziltas, MD, Assistant Professor, Department of Gastroenterology, Baskent University Istanbul Hospital, Oymaci Street, No:7, 34662 Altunizade, Istanbul, Turkey. safakkiziltas@hotmail.com
Telephone: +90-216-5541500 Fax: +90-216-6519858
Received: June 12, 2016
Peer-review started: June 17, 2016
First decision: July 11, 2016
Revised: August 17, 2016
Accepted: September 21, 2016
Article in press: September 22, 2016
Published online: November 18, 2016
Processing time: 157 Days and 11 Hours
Abstract

Toll-like receptors (TLRs) are pattern recognition receptors that participate in host defense by recognizing pathogen-associated molecular patterns alongside inflammatory processes by recognizing damage associated molecular patterns. Given constant exposure to pathogens from gut, strict control of TLR-associated signaling pathways is essential in the liver, which otherwise may lead to inappropriate production of pro-inflammatory cytokines and interferons and may generate a predisposition to several autoimmune and chronic inflammatory diseases. The liver is considered to be a site of tolerance induction rather than immunity induction, with specificity in hepatic cell functions and distribution of TLR. Recent data emphasize significant contribution of TLR signaling in chronic liver diseases via complex immune responses mediating hepatocyte (i.e., hepatocellular injury and regeneration) or hepatic stellate cell (i.e., fibrosis and cirrhosis) inflammatory or immune pathologies. Herein, we review the available data on TLR signaling, hepatic expression of TLRs and associated ligands, as well as the contribution of TLRs to the pathophysiology of hepatic diseases.

Keywords: Toll-like receptors; Innate immunity; Liver disease; Pathophysiology; Signaling

Core tip: Toll-like receptors (TLRs) are known to be pattern recognition receptors that recognize pathogen- and damage-associated molecular pattern molecules and thus participate in the activation of innate immune system. TLR signaling plays a significant role in liver diseases, whereas inflammatory or immune pathologies targeting distinct liver cells are based on complex immune responses. Herein, we review the current data on TLR signaling, hepatic expression of TLRs and associated ligands, as well as the contribution of TLRs to the pathophysiology of hepatic diseases.