A1 Refereed original research article in a scientific journal
Evidence that TLR4 Is Not a Receptor for Saturated Fatty Acids but Mediates Lipid-Induced Inflammation by Reprogramming Macrophage Metabolism
Authors: Lancaster GI, Langley KG, Berglund NA, Kammoun HL, Reibe S, Estevez E, Weir J, Mellett NA, Pernes G, Conway JRW, Lee MKS, Timpson P, Murphy AJ, Masters SL, Gerondakis S, Kaczorowski DC, Bartonicek N, Meikle PJ, Dinger ME, Febbraio MA, Bond PJ
Publication year: 2018
Journal: Cell Metabolism
Journal name in source: Cell metabolism
Journal acronym: Cell Metab
Volume: 27
Issue: 5
First page : 1096
Last page: 1110.e5
Number of pages: 20
ISSN: 1550-4131
eISSN: 1932-7420
DOI: https://doi.org/10.1016/j.cmet.2018.03.014(external)
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.
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.