PGE2 enhanced TNFα-mediated IL-8 induction in monocytic cell lines and PBMC
F Neuschäfer-Rube1, A Pathe-Neuschäfer-Rube1, S Hippenstiel2
1Universität Potsdam, Institut für Ernährungswissenschaft, Arthur-Scheunert-Allee 114-116, 14558 Nuthetal, Germany.
Background & Purpose:
Recent studies suggested a role of prostaglandin E2 (PGE2) in the expression of the chemokine IL-8 by monocytes. The function of EP4 receptor for TNFα-induced IL-8 expression was studied in monocytic cell lines.
Experimental Approach:
IL-8 mRNA and protein induction as well as IL-8 promoter activity and transcription factor activation were assessed in monocytic cell lines, primary blood mononuclear cells (PBMC) and transgenic HEK293 cells expressing the EP4 receptor.
Key Results:
In monocytic cell lines THP-1, MonoMac and U937 PGE2 had only a marginal impact on IL-8 induction but strongly enhanced TNFα-induced IL-8 mRNA and protein synthesis. Similarly, in PBMC IL-8 mRNA induction was larger by simultaneous stimulation with TNFα and PGE2 than by either stimulus alone. The EP4 receptor subtype was the most abundant EP receptor in all three cell lines and in PBMC. Stimulation of THP-1 cells with an EP4 specific agonist enhanced TNFα-induced IL-8 mRNA and protein formation to the same extent as PGE2. In HEK293 cells expressing EP4, but not in wild type HEK293 cells lacking EP4, PGE2 enhanced TNFα-induced IL-8 protein and mRNA synthesis. In THP-1 cells, the enhancement of TNFα-mediated IL-8 mRNA induction by PGE2 was mimicked by a PKA-activator. Furthermore in these cells PGE2 induced expression of transcription factor C/EBPß, enhanced NF-κB activation by TNFα and inhibited TNFα-mediated AP-1 activation. PGE2 and TNFα synergistically activated transcription factor CREB, induced C/EBPß expression and enhanced the activity of an IL-8 promoter fragment containing -223 bp upstream of the transcription start site.
Conclusions And Implications:
These findings suggest that a combined stimulation of TNFα and PGE2/EP4 signal chains in monocytic cells leads to maximal IL-8 promoter activity, as well as IL-8 mRNA and protein induction, by activating the PKA/CREB/C/EBPß as well as NF-κB signal chains.
Insights
Prostaglandin E2 (PGE2) and TNFα synergistically enhance Interleukin-8 (IL-8) production in monocytes via the EP4 receptor. This involves activating key signaling pathways, leading to increased IL-8 expression.
Area of Science:
- Immunology
- Molecular Biology
- Cell Biology
Background:
- Prostaglandin E2 (PGE2) is implicated in regulating chemokine Interleukin-8 (IL-8) expression in monocytes.
- The specific role of the EP4 receptor in TNFα-induced IL-8 expression requires further investigation.
Purpose of the Study:
- To elucidate the function of the EP4 receptor in TNFα-induced IL-8 expression within monocytic cell lines.
- To understand the molecular mechanisms underlying PGE2 and TNFα co-stimulation on IL-8 production.
Main Methods:
- Assessed IL-8 mRNA and protein induction, promoter activity, and transcription factor activation in monocytic cell lines (THP-1, MonoMac, U937), primary blood mononuclear cells (PBMC), and EP4-expressing HEK293 cells.
- Utilized EP4-specific agonists and pathway activators (PKA) to dissect signaling cascades.
Main Results:
- PGE2 alone had a minor effect on IL-8 induction, but significantly enhanced TNFα-induced IL-8 mRNA and protein synthesis in monocytic cells and PBMC.
- EP4 was the predominant EP receptor subtype. Stimulation with an EP4 agonist mimicked PGE2's effect on TNFα-induced IL-8.
- PGE2 modulated transcription factors, including inducing C/EBPß, enhancing NF-κB activation, and inhibiting AP-1 activation by TNFα. PGE2 and TNFα synergistically activated CREB.
Conclusions:
- Combined TNFα and PGE2/EP4 signaling in monocytes maximally induces IL-8 promoter activity, mRNA, and protein.
- This synergistic effect is mediated through the activation of PKA/CREB/C/EBPß and NF-κB signaling pathways.
More Related Videos
07:58Quantitative Imaging of Lineage-specific Toll-like Receptor-mediated Signaling in Monocytes and Dendritic Cells from Small Samples of Human Blood
Published on: April 16, 2012
06:27Use of a Monocyte Monolayer Assay to Evaluate Fcγ Receptor-mediated Phagocytosis
Published on: January 2, 2017
Related Concept Videos
01:16Cell Lines
01:23Lossless Lines
01:39Receptor-mediated Endocytosis
01:16Induction
A...
03:00Self-Evaluation: Self-Enhancement and Self-Verification
01:40Cell-mediated Immune Responses