title: Tumor necrosis factor α primes cerebral endothelial cells for erythropoietin-induced angiogenesis.
abstract: Erythropoietin (EPO) enhances angiogenesis in the ischemic brain. Stroke induces secretion of tumor necrosis factor α (TNF-α). We investigated the effect of TNF-α on EPO-induced in vitro angiogenesis in cerebral endothelial cells. Using a capillary-like tubular formation assay, we found that transient incubation of primary rat cerebral microvascular endothelial cells (RECs) with TNF-α substantially upregulated EPO receptor (EPOR) expression and addition of EPO into TNF-α-treated RECs significantly augmented the capillary-like tube formation. Blockage of TNF receptor 1 (TNFR1) suppressed TNF-α-upregulated EPOR expression and abolished EPO-induced tube formation. Attenuation of endogenous EPOR with small interfering RNA (siRNA) also inhibited EPO-enhanced tube formation. Treatment of RECs with EPO activated nuclear factor-kappa B (NF-κB) and Akt. Incubation of the TNF-α-treated endothelial cells with EPO activated vascular endothelial growth factor (VEGF), VEGF receptor 2 (VEGFR2), angiopoietin 1 (Ang1), and Tie2. Blockage of VEGFR2 and Tie2 resulted in reduction of EPO-augmented tube formation. These data indicate that interaction of TNF-α with TNFR1 sensitizes cerebral endothelial cells for EPO-induced angiogenesis by upregulation of EPOR, which amplifies the effect of EPO on activation of the VEGF/VEGFR2 and Ang1/Tie2 pathways. Our results provide the evidence for crosslink between TNF and EPOR to coordinate the onset of angiogenesis in cerebral endothelial cells.
authors.affiliation: Department of Neurology, Henry Ford Health Sciences Center, Detroit, Michigan 48202, USA.
authors.forename: Lei
authors.initials: L
authors.lastname: Wang
authors.forename: Michael
authors.initials: M
authors.lastname: Chopp
authors.forename: Hua
authors.initials: H
authors.lastname: Teng
authors.forename: Marianne
authors.initials: M
authors.lastname: Bolz
authors.forename: Moniche-Alvarez
authors.initials: MA
authors.lastname: Francisco
authors.forename: Moniche Ãlvarez
authors.initials: MÃ
authors.lastname: Francisco
authors.forename: Danielle Marie
authors.initials: DM
authors.lastname: Aluigi
authors.forename: Xin Li
authors.initials: XL
authors.lastname: Wang
authors.forename: Rui Lan
authors.initials: RL
authors.lastname: Zhang
authors.forename: Søren
authors.initials: S
authors.lastname: Chrsitensen
authors.forename: Thomas N
authors.initials: TN
authors.lastname: Sager
authors.forename: Alexandra
authors.initials: A
authors.lastname: Szalad
authors.forename: Zheng Gang
authors.initials: ZG
authors.lastname: Zhang
mesh_terms: D043925:Angiogenesis Inducing Agents / Q000378:metabolism / Q000494:pharmacology*; D042683:Angiopoietin-1 / Q000096:biosynthesis; D000818:Animals; D015153:Blotting, Western; D002196:Capillaries / Q000254:growth & development; D049109:Cell Proliferation / Q000187:drug effects; D004357:Drug Synergism; D042783:Endothelial Cells / Q000187:drug effects*; D004921:Erythropoietin / Q000494:pharmacology*; D007150:Immunohistochemistry; D008297:Male; D016328:NF-kappa B / Q000096:biosynthesis; D018919:Neovascularization, Physiologic / Q000187:drug effects*; D051058:Oncogene Protein v-akt / Q000096:biosynthesis; D051381:Rats; D017208:Rats, Wistar; D017467:Receptors, Erythropoietin / Q000187:drug effects / Q000235:genetics; D047888:Receptors, Tumor Necrosis Factor, Type I / Q000037:antagonists & inhibitors; D047889:Receptors, Tumor Necrosis Factor, Type II / Q000037:antagonists & inhibitors; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014162:Transfection; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*; D042461:Vascular Endothelial Growth Factor A / Q000096:biosynthesis
chemical_list: D043925:Angiogenesis Inducing Agents; D042683:Angiopoietin-1; D016328:NF-kappa B; D017467:Receptors, Erythropoietin; D047888:Receptors, Tumor Necrosis Factor, Type I; D047889:Receptors, Tumor Necrosis Factor, Type II; D014409:Tumor Necrosis Factor-alpha; D042461:Vascular Endothelial Growth Factor A; D004921:Erythropoietin; D051058:Oncogene Protein v-akt