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Saturated fatty acids do not directly stimulate Toll-like receptor signaling

Clett Erridge1, Nilesh J Samani

  • 1Department of Cardiovascular Sciences, University of Leicester, Glenfield Hospital, Leicester, UK. ce55@le.ac.uk

Arteriosclerosis, Thrombosis, and Vascular Biology
|August 8, 2009
PubMed
Abstract

Insights

Saturated fatty acids (SFAs) do not directly activate Toll-like receptors (TLRs). Previously observed effects were due to contamination in a common laboratory reagent, not the SFAs themselves.

Area of Science:

  • Immunology
  • Nutrition Science
  • Molecular Biology

Background:

  • Toll-like receptors (TLRs) are key initiators of inflammatory responses to microbial molecules.
  • Dietary saturated fatty acids (SFAs) have been hypothesized to act as endogenous ligands for TLR2 and TLR4, potentially contributing to inflammatory diseases like atherosclerosis and insulin resistance.

Purpose of the Study:

  • To investigate the direct effects of SFAs on TLR-dependent signaling pathways.
  • To clarify the role of SFAs in initiating inflammatory responses mediated by TLRs.

Main Methods:

  • Experiments were conducted using various cell types, including HEK-293 cells, macrophages, endothelial cells, and others.
  • TLR-dependent signaling was assessed in response to SFAs, both alone and complexed with bovine serum albumin (BSA).
  • Analysis included evaluating TLR-dependent signaling pathways and the expression of TLR-target genes.

Main Results:

  • SFAs complexed with fatty-acid-free BSA stimulated TLR-dependent signaling in transfected HEK-293 cells.
  • Further investigation revealed that LPS and lipopeptide contamination in the BSA, not the SFAs, caused this stimulation.
  • SFAs alone did not stimulate TLR-dependent signaling pathways or TLR-target gene expression across multiple cell types.

Conclusions:

  • SFAs do not directly activate TLR-dependent signaling pathways.
  • Contamination in fatty-acid-free BSA with LPS and lipopeptides accounts for previously reported TLR2 and TLR4 stimulation by SFAs.
  • Alternative mechanisms likely explain the association between dietary fat intake and TLR-associated pathologies.

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