title: New Insights into the Pro-Inflammatory Activities of Ang1 on Neutrophils: Induction of MIP-1β Synthesis and Release.
abstract: 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.
authors.affiliation: Research center, Montreal Heart Institute, Montreal (Quebec), Canada.|Departments of pharmacology, Faculty of medicine, Université de Montréal, Montreal (Quebec), Canada.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Dumas
authors.affiliation: Research center, Montreal Heart Institute, Montreal (Quebec), Canada.|Departments of pharmacology, Faculty of medicine, Université de Montréal, Montreal (Quebec), Canada.
authors.forename: Paul-Eduard
authors.initials: PE
authors.lastname: Neagoe
authors.affiliation: Pulmonary Division/Research, Faculty of Medicine, Université de Sherbrooke, Sherbrooke (Quebec), Canada.
authors.forename: Patrick P
authors.initials: PP
authors.lastname: McDonald
authors.affiliation: Research center, Montreal Heart Institute, Montreal (Quebec), Canada.|Departments of medicine, Faculty of medicine, Université de Montréal, Montreal (Quebec), Canada.
authors.forename: Michel
authors.initials: M
authors.lastname: White
authors.affiliation: Research center, Montreal Heart Institute, Montreal (Quebec), Canada.|Departments of pharmacology, Faculty of medicine, Université de Montréal, Montreal (Quebec), Canada.
authors.forename: Martin G
authors.initials: MG
authors.lastname: Sirois
mesh_terms: D042683:Angiopoietin-1 / Q000037:antagonists & inhibitors / Q000502:physiology*; D054407:Chemokine CCL4 / Q000096:biosynthesis* / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D018836:Inflammation Mediators / Q000502:physiology*; D016328:NF-kappa B / Q000378:metabolism; D009504:Neutrophils / Q000187:drug effects / Q000378:metabolism*
chemical_list: C467630:ANGPT1 protein, human; D042683:Angiopoietin-1; D054407:Chemokine CCL4; D004791:Enzyme Inhibitors; D018836:Inflammation Mediators; D016328:NF-kappa B