New Insights into the Pro-Inflammatory Activities of Ang1 on Neutrophils: Induction of MIP-1β Synthesis and Release

• Published in: PloS one Vol. 11; no. 9; p. e0163140
• Main Authors: Dumas, Elizabeth, Neagoe, Paul-Eduard, McDonald, Patrick P, White, Michel, Sirois, Martin G
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 15-09-2016; Public Library of Science (PLoS)
• Subjects: 1-Phosphatidylinositol 3-kinase; Actinomycin; Angiogenesis; Angiopoietin; Angiopoietin-1 - antagonists & inhibitors; Angiopoietin-1 - physiology; Biology and Life Sciences; Cell activation; Cell adhesion & migration; Chemokine CCL4 - biosynthesis; Chemokine CCL4 - metabolism; Chronic illnesses; Cycloheximide; Cytokines; Dendritic cells; Downstream effects; Enzyme Inhibitors - pharmacology; Enzyme-linked immunosorbent assay; Gene expression; Heart; Humans; Inflammation; Inflammation Mediators - physiology; Inhibitors; Interleukin; Interleukin 8; Intracellular; Kinases; Laboratories; Leukocyte migration; Leukocytes (neutrophilic); Macrophage inflammatory protein; Macrophages; MAP kinase; Medicine; Medicine and Health Sciences; Neutrophils; Neutrophils - drug effects; Neutrophils - metabolism; NF-kappa B - metabolism; NF-κB protein; Pharmacology; Physiology; Platelet-activating factor; Pretreatment; Protein biosynthesis; Protein synthesis; Proteins; Research and Analysis Methods; Transcription; Vascular endothelial growth factor; Viability
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0163140

We reported the expression of angiopoietin Tie2 receptor on human neutrophils and the capacity of angiopoietins (Ang1 and Ang2) to induce pro-inflammatory activities, such as platelet-activating factor synthesis, β2-integrin activation and neutrophil migration. Recently, we observed differential effects between both angiopoietins, namely, the capacity of Ang1, but not Ang2, to promote rapid interleukin-8 synthesis and release, as well as neutrophil viability. Herein, we addressed whether Ang1 and/or Ang2 could modulate the synthesis and release of macrophage inflammatory protein-1β (MIP-1β) by neutrophils. Neutrophils were isolated from blood of healthy volunteers; intracellular and extracellular MIP-1β protein concentrations were assessed by ELISA. After 24 hours, the basal intracellular and extracellular MIP-1β protein concentrations were ≈500 and 100 pg/106 neutrophils, respectively. Treatment with Ang1 (10 nM) increased neutrophil intracellular and extracellular MIP-1β concentrations by 310 and 388% respectively. Pretreatment with PI3K (LY294002), p38 MAPK (SB203580) and MEK (U0126) inhibitors completely inhibited Ang1-mediated increase of MIP-1β intracellular and extracellular protein levels. Pretreatment with NF-κB complex inhibitors, namely Bay11-7085 and IKK inhibitor VII or with a transcription inhibitor (actinomycin D) and protein synthesis inhibitor (cycloheximide), did also abrogate Ang1-mediated increase of MIP-1β intracellular and extracellular protein levels. We validated by RT-qPCR analyses the effect of Ang1 on the induction of MIP-1β mRNA levels. Our study is the first one to report Ang1 capacity to induce MIP-1β gene expression, protein synthesis and release from neutrophils, and that these effects are mediated by PI3K, p38 MAPK and MEK activation and downstream NF-κB activation.