title: CCL2-dependent infiltrating macrophages promote angiogenesis in progressive liver fibrosis.
abstract: OBJECTIVE
  In chronic liver injury, angiogenesis, the formation of new blood vessels from pre-existing ones, may contribute to progressive hepatic fibrosis and to development of hepatocellular carcinoma. Although hypoxia-induced expression of vascular endothelial growth factor (VEGF) occurs in advanced fibrosis, we hypothesised that inflammation may endorse hepatic angiogenesis already at early stages of fibrosis.
  
  
  METHODS
  Angiogenesis in livers of c57BL/6 mice upon carbon tetrachloride- or bile duct ligation-induced chronic hepatic injury was non-invasively monitored using in vivo contrast-enhanced micro computed tomography (µCT) and ex vivo anatomical µCT after hepatic Microfil perfusion. Functional contributions of monocyte-derived macrophage subsets for angiogenesis were explored by pharmacological inhibition of CCL2 using the Spiegelmer mNOX-E36.
  
  
  RESULTS
  Contrast-enhanced in vivo µCT imaging allowed non-invasive monitoring of the close correlation of angiogenesis, reflected by functional hepatic blood vessel expansion, with experimental fibrosis progression. On a cellular level, inflammatory monocyte-derived macrophages massively accumulated in injured livers, colocalised with newly formed vessels in portal tracts and exhibited pro-angiogenic gene profiles including upregulated VEGF and MMP9. Functional in vivo and anatomical ex vivo µCT analyses demonstrated that inhibition of monocyte infiltration by targeting the chemokine CCL2 prevented fibrosis-associated angiogenesis, but not fibrosis progression. Monocyte-derived macrophages primarily fostered sprouting angiogenesis within the portal vein tract. Portal vein diameter as a measure of portal hypertension depended on fibrosis, but not on angiogenesis.
  
  
  CONCLUSIONS
  Inflammation-associated angiogenesis is promoted by CCL2-dependent monocytes during fibrosis progression. Innovative in vivo µCT methodology can accurately monitor angiogenesis and antiangiogenic therapy effects in experimental liver fibrosis.
authors.affiliation: Department of Experimental Molecular Imaging, Helmholtz Institute for Biomedical Engineering, Medical Faculty, RWTH University, Aachen, Germany.|Institute of Pathology, Medical Faculty, RWTH University, Aachen, Germany.
authors.forename: Josef
authors.initials: J
authors.lastname: Ehling
authors.affiliation: Department of Medicine III, Medical Faculty, RWTH University, Aachen, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Bartneck
authors.affiliation: Department of Medicine III, Medical Faculty, RWTH University, Aachen, Germany.
authors.forename: Xiao
authors.initials: X
authors.lastname: Wei
authors.affiliation: Department of Experimental Molecular Imaging, Helmholtz Institute for Biomedical Engineering, Medical Faculty, RWTH University, Aachen, Germany.
authors.forename: Felix
authors.initials: F
authors.lastname: Gremse
authors.affiliation: Department of Medicine III, Medical Faculty, RWTH University, Aachen, Germany.
authors.forename: Viktor
authors.initials: V
authors.lastname: Fech
authors.affiliation: Department of Experimental Molecular Imaging, Helmholtz Institute for Biomedical Engineering, Medical Faculty, RWTH University, Aachen, Germany.
authors.forename: Diana
authors.initials: D
authors.lastname: Möckel
authors.affiliation: Department of Medicine III, Medical Faculty, RWTH University, Aachen, Germany.
authors.forename: Christer
authors.initials: C
authors.lastname: Baeck
authors.affiliation: Institute of Pathology, University Bonn, Bonn, Germany.
authors.forename: Kanishka
authors.initials: K
authors.lastname: Hittatiya
authors.affiliation: NOXXON Pharma AG, Berlin, Germany.
authors.forename: Dirk
authors.initials: D
authors.lastname: Eulberg
authors.affiliation: Department of Medicine III, Medical Faculty, RWTH University, Aachen, Germany.
authors.forename: Tom
authors.initials: T
authors.lastname: Luedde
authors.affiliation: Department of Experimental Molecular Imaging, Helmholtz Institute for Biomedical Engineering, Medical Faculty, RWTH University, Aachen, Germany.
authors.forename: Fabian
authors.initials: F
authors.lastname: Kiessling
authors.affiliation: Department of Medicine III, Medical Faculty, RWTH University, Aachen, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Trautwein
authors.affiliation: Department of Experimental Molecular Imaging, Helmholtz Institute for Biomedical Engineering, Medical Faculty, RWTH University, Aachen, Germany.|Department of Targeted Therapeutics, MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, Enschede, The Netherlands.|Department of Pharmaceutics, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, The Netherlands.
authors.forename: Twan
authors.initials: T
authors.lastname: Lammers
authors.affiliation: Department of Medicine III, Medical Faculty, RWTH University, Aachen, Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Tacke
mesh_terms: D000818:Animals; D052157:Aptamers, Nucleotide / Q000494:pharmacology*; D002251:Carbon Tetrachloride / Q000494:pharmacology; D018932:Chemokine CCL2 / Q000037:antagonists & inhibitors / Q000378:metabolism; D004195:Disease Models, Animal; D018450:Disease Progression; D007249:Inflammation / Q000378:metabolism; D008099:Liver / Q000473:pathology; D008103:Liver Cirrhosis / Q000150:complications / Q000209:etiology / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D008264:Macrophages / Q000378:metabolism / Q000473:pathology; D051379:Mice; D008810:Mice, Inbred C57BL; D009389:Neovascularization, Pathologic / Q000209:etiology / Q000378:metabolism / Q000473:pathology / Q000517:prevention & control; D055114:X-Ray Microtomography / Q000379:methods
chemical_list: D052157:Aptamers, Nucleotide; D018932:Chemokine CCL2; C528578:NOX-E36-3'PEG, mouse; D002251:Carbon Tetrachloride
keywords: ANGIOGENESIS; CHEMOKINES; COMPUTER TOMOGRAPHY; FIBROSIS; MACROPHAGES