Differences in PGE2 production between primary human monocytes and differentiated macrophages: role of IL-1β and TRIF/IRF3

PLoS One. 2014 May 28;9(5):e98517. doi: 10.1371/journal.pone.0098517. eCollection 2014.


Prostaglandin E2 (PGE2) is induced in vivo by bacterial products including TLR agonists. To determine whether PGE2 is induced directly or via IL-1β, human monocytes and macrophages were cultured with LPS or with Pam3CSK4 in presence of caspase-1 inhibitor, ZVAD, or IL-1R antagonist, Kineret. TLR agonists induced PGE2 in macrophages exclusively via IL-1β-independent mechanisms. In contrast, ZVAD and Kineret reduced PGE2 production in LPS-treated (but not in Pam3CSK4-treated) monocytes, by 30-60%. Recombinant human IL-1β augmented COX-2 and mPGES-1 mRNA and PGE2 production in LPS-pretreated monocytes but not in un-primed or Pam3CSK4-primed monocytes. This difference was explained by the finding that LPS but not Pam3CSK4 induced phosphorylation of IRF3 in monocytes suggesting activation of the TRIF signaling pathway. Knocking down TRIF, TRAM, or IRF3 genes by siRNA inhibited IL-1β-induced COX-2 and mPGES-1 mRNA. Blocking of TLR4 endocytosis during LPS priming prevented the increase in PGE2 production by exogenous IL-1β. Our data showed that TLR2 agonists induce PGE2 in monocytes independently from IL-1β. In the case of TLR4, IL-1β augments PGE2 production in LPS-primed monocytes (but not in macrophages) through a mechanism that requires TLR4 internalization and activation of the TRIF/IRF3 pathway. These findings suggest a key role for blood monocytes in the rapid onset of fever in animals and humans exposed to bacterial products and some novel adjuvants.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptor Proteins, Vesicular Transport / metabolism*
  • Animals
  • Blotting, Western
  • Cells, Cultured
  • Cyclooxygenase 2 / metabolism
  • Dinoprostone / biosynthesis*
  • Fever / metabolism*
  • Fever / microbiology
  • Flow Cytometry
  • Humans
  • Interferon Regulatory Factor-3 / metabolism
  • Interleukin 1 Receptor Antagonist Protein
  • Interleukin-1beta / metabolism*
  • Lipopeptides
  • Lipopolysaccharides
  • Macrophages / metabolism*
  • Mice
  • Mice, Inbred NOD
  • Monocytes / metabolism*
  • Oligopeptides
  • Phosphorylation
  • RNA Interference
  • RNA, Small Interfering / genetics
  • Signal Transduction / physiology*
  • Toll-Like Receptor 2 / agonists


  • Adaptor Proteins, Vesicular Transport
  • IRF3 protein, human
  • Interferon Regulatory Factor-3
  • Interleukin 1 Receptor Antagonist Protein
  • Interleukin-1beta
  • Lipopeptides
  • Lipopolysaccharides
  • Oligopeptides
  • Pam(3)CSK(4) peptide
  • RNA, Small Interfering
  • TICAM1 protein, human
  • TLR2 protein, human
  • Toll-Like Receptor 2
  • benzyloxycarbonyl-valyl-alanyl-aspartic acid
  • Cyclooxygenase 2
  • PTGS2 protein, human
  • Dinoprostone

Grant support

This project has been funded in part with Federal funds from the Critical Path Initiative at CBER, FDA and from the Biomedical Advanced Research and Development Authority (BARDA), HHS. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.