Evidence that TLR4 Is Not a Receptor for Saturated Fatty Acids but Mediates Lipid-Induced Inflammation by Reprogramming Macrophage Metabolism.

Graeme I Lancaster; Katherine G Langley; Nils Anton Berglund; Helene L Kammoun; Saskia Reibe; Emma Estevez; Jacquelyn Weir; Natalie A Mellett; Gerard Pernes; James R W Conway; Man K S Lee; Paul Timpson; Andrew J Murphy; Seth L Masters; Steve Gerondakis; Nenad Bartonicek; Dominik C Kaczorowski; Marcel E Dinger; Peter J Meikle; Peter J Bond; Mark A Febbraio
Abstract
Chronic inflammation is a hallmark of obesity and is linked to the development of numerous diseases. The activation of toll-like receptor 4 (TLR4) by long-chain saturated fatty acids (lcSFAs) is an important process in understanding how obesity initiates inflammation. While experimental evidence supports an important role for TLR4 in obesity-induced inflammation in vivo, via a mechanism thought to involve direct binding to and activation of TLR4 by lcSFAs, several lines of evidence argue against lcSFAs being direct TLR4 agonists. Using multiple orthogonal approaches, we herein provide evidence that while loss-of-function models confirm that TLR4 does, indeed, regulate lcSFA-induced inflammation, TLR4 is not a receptor for lcSFAs. Rather, we show that TLR4-dependent priming alters cellular metabolism, gene expression, lipid metabolic pathways, and membrane lipid composition, changes that are necessary for lcSFA-induced inflammation. These results reconcile previous discordant observations and challenge the prevailing view of TLR4's role in initiating obesity-induced inflammation.
Journal CELL METABOLISM
ISSN 1932-7420
Published 01 May 2018
Volume 27
Issue 5
Pages 1096-1110.e5
DOI 10.1016/j.cmet.2018.03.014
Type Journal Article
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