Synergistic up-regulation of vascular endothelial growth factor expression in murine macrophages by adenosine A(2A) receptor agonists and endotoxin
| Autor: | Grace Pinhal-Enfield, Michael A. Schwarzschild, Anthony Rosania, Samuel Leibovich, Genie Elson, Madhuri Ramanathan, Jiang-Fan Chen, Bruce N. Cronstein, Marlene A. Jacobson, Carmen Montesinos, Paula C. Belem, J. Stephen Fink |
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| Rok vydání: | 2002 |
| Předmět: |
Lipopolysaccharides
Male Vascular Endothelial Growth Factor A Adenosine Receptor expression Nitric Oxide Synthase Type II Adenosine-5'-(N-ethylcarboxamide) Endothelial Growth Factors chemistry.chemical_compound Mice Drosophila Proteins Receptor Cells Cultured Mice Knockout Lymphokines Mice Inbred C3H Membrane Glycoproteins Reverse Transcriptase Polymerase Chain Reaction Triazines Vascular Endothelial Growth Factors Toll-Like Receptors Up-Regulation Vascular endothelial growth factor CCPA Theobromine Female medicine.drug Signal Transduction medicine.medical_specialty Receptor Adenosine A2A Blotting Western Receptors Cell Surface Biology Nitric Oxide Pathology and Forensic Medicine Interferon-gamma Internal medicine Phenethylamines medicine Purinergic P1 Receptor Agonists Animals RNA Messenger Protein Kinase Inhibitors Receptors Purinergic P1 Triazoles Adenosine A3 receptor Adenosine receptor Molecular biology Mice Inbred C57BL Toll-Like Receptor 4 Endocrinology chemistry Xanthines TLR4 Macrophages Peritoneal Nitric Oxide Synthase Regular Articles |
| Zdroj: | The American journal of pathology. 160(6) |
| ISSN: | 0002-9440 |
| Popis: | Under normoxic conditions, macrophages from C57BL mice produce low levels of vascular endothelial growth factor (VEGF). Hypoxia stimulates VEGF expression by approximately 500%; interferon-gamma (IFN-gamma) with endotoxin [lipopolysaccharide (LPS)] also stimulates VEGF expression by approximately 50 to 150% in an inducible nitric oxide synthase (iNOS)-dependent manner. Treatment of normoxic macrophages with 5'-N-ethyl-carboxamido-adenosine (NECA), a nonselective adenosine A(2) receptor agonist, or with 2-[p-(2-carboxyethyl)-phenylethyl amino]-5'-N-ethyl-carboxamido-adenosine (CGS21680), a specific adenosine A(2A) receptor agonist, modestly increases VEGF expression, whereas 2-chloro-N(6)-cyclopentyl adenosine (CCPA), an adenosine A(1) agonist, does not. Treatment with LPS (0 to 1000 ng/ml), or with IFN-gamma (0 to 300 U/ml), does not affect VEGF expression. In the presence of LPS (EC(50)10 ng/ml), but not of IFN-gamma, both NECA and CGS21680 synergistically up-regulate VEGF expression by as much as 10-fold. This VEGF is biologically active in vivo in the rat corneal bioassay of angiogenesis. Inhibitors of iNOS do not affect this synergistic induction of VEGF, and macrophages from iNOS-/- mice produce similar levels of VEGF as wild-type mice, indicating that NO does not play a role in this induction. Under hypoxic conditions, VEGF expression is slightly increased by adenosine receptor agonists but adenosine A(2) or A(1) receptor antagonists 3,7-dimethyl-1-propargyl xanthine (DMPX), ZM241385, and 8-cyclopentyl-1,3-dipropylxanthine (DCPCX) do not modulate VEGF expression. VEGF expression is also not reduced in hypoxic macrophages from A(3)-/- and A(2A)-/- mice. Thus, VEGF expression by hypoxic macrophages does not seem to depend on endogenously released or exogenous adenosine. VEGF expression is strongly up-regulated by LPS/NECA in macrophages from A(3)-/- but not A(2A)-/- mice, confirming the role of adenosine A(2A) receptors in this pathway. LPS with NECA strongly up-regulates VEGF expression by macrophages from C(3)H/HeN mice (with intact Tlr4 receptors), but not by macrophages from C(3)H/HeJ mice (with mutated, functionally inactive Tlr4 receptors), implicating signaling through the Tlr4 pathway in this synergistic up-regulation. Finally, Western blot analysis of adenosine A(2A) receptor expression indicated that the synergistic interaction of LPS with A(2A) receptor agonists does not involve up-regulation of A(2A) receptors by LPS. These results indicate that in murine macrophages there is a novel pathway regulating VEGF production, that involves the synergistic interaction of adenosine A(2A) receptor agonists through A(2A) receptors with LPS through the Tlr4 pathway, resulting in the strong up-regulation of VEGF expression by macrophages in a hypoxia- and NO-independent manner. |
| Databáze: | OpenAIRE |
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