Soluble DPP4 induces inflammation and proliferation of human smooth muscle cells via protease-activated receptor 2.

Abstract

DPP4 is an ubiquitously expressed cell-surface protease that is shedded to the circulation as soluble DPP4 (sDPP4). We recently identified sDPP4 as a novel adipokine potentially linking obesity to the metabolic syndrome. The aim of this study was to investigate direct effects of sDPP4 on human vascular smooth muscle cells (hVSMCs) and to identify responsible signaling pathways. Using physiological concentrations of sDPP4, we could observe a concentration-dependent activation of ERK1/2 (3-fold) after 6h, which remained stable for up to 24h. Additionally, sDPP4 treatment induced a 1.5-fold phosphorylation of the NF-κB subunit p65. In accordance with sDPP4-induced stress and inflammatory signaling, sDPP4 also stimulates hVSMC proliferation. Furthermore we could observe an increased expression and secretion of pro-inflammatory cytokines like interleukin (IL)-6, IL-8 and MCP-1 (2.5-, 2.4- and 1.5-fold, respectively) by the sDPP4 treatment. All direct effects of sDPP4 on signaling, proliferation and inflammation could completely be prevented by DPP4 inhibition. Bioinformatic analysis and signaling signature induced by sDPP4 suggest that sDPP4 might be an agonist for PAR2. After the silencing of PAR2, the sDPP4-induced ERK activation as well as the proliferation was totally abolished. Additionally, the sDPP4-induced upregulation of IL-6 and IL-8 could completely be prevented by the PAR2 silencing. In conclusion, we show for the first time that sDPP4 directly activates the MAPK and NF-κB signaling cascade involving PAR2 and resulting in the induction of inflammation and proliferation of hVSMC. Thus, our in vitro data might extend the current view of sDPP4 action and shed light on cardiovascular effects of DPP4-inhibitors.

• Authors: Nina Wronkowitz, Sven W Görgens, Tania Romacho, Laura A Villalobos, Carlos F Sánchez-Ferrer, Concepción Peiró, Henrike Sell, Jürgen Eckel
• Journal: Biochimica et biophysica acta (Biochim Biophys Acta) Vol. 1842 Issue 9 Pg. 1613-21 (Sep 2014) ISSN: 0006-3002 [Print] Netherlands
• PMID: 24928308 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: Copyright © 2014 Elsevier B.V. All rights reserved.

Chemical References

• 5-isoxazoyl-cyclohexylalanyl-isoleucyl-spiroindane-1,4'-piperidine
• Cytokines
• Dipeptides
• Isoxazoles
• RNA, Messenger
• RNA, Small Interfering
• Receptor, PAR-2
• NOS2 protein, human
• Nitric Oxide Synthase Type II
• MAPK1 protein, human
• Mitogen-Activated Protein Kinase 1
• Mitogen-Activated Protein Kinase 3
• DPP4 protein, human
• Dipeptidyl Peptidase 4

Topics

• Amino Acid Sequence
• Blotting, Western
• Cell Proliferation
• Cells, Cultured
• Cytokines (genetics, metabolism)
• Dipeptides (pharmacology)
• Dipeptidyl Peptidase 4 (genetics, metabolism)
• Enzyme-Linked Immunosorbent Assay
• Humans
• Inflammation (genetics, metabolism, pathology)
• Isoxazoles (pharmacology)
• Mitogen-Activated Protein Kinase 1 (genetics, metabolism)
• Mitogen-Activated Protein Kinase 3 (genetics, metabolism)
• Molecular Sequence Data
• Muscle, Smooth, Vascular (drug effects, metabolism, pathology)
• Nitric Oxide Synthase Type II (genetics, metabolism)
• Phosphorylation (drug effects)
• RNA, Messenger (genetics)
• RNA, Small Interfering (genetics)
• Real-Time Polymerase Chain Reaction
• Receptor, PAR-2 (antagonists & inhibitors, genetics, metabolism)
• Reverse Transcriptase Polymerase Chain Reaction
• Sequence Homology, Amino Acid