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CCL2-dependent infiltrating macrophages promote angiogenesis in progressive liver fibrosis.

ABSTRACT: 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.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.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.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.

SUBMITTER: Ehling J

PROVIDER: S-EPMC4216733 | biostudies-literature | 2014 Dec

REPOSITORIES: biostudies-literature

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CCL2-dependent infiltrating macrophages promote angiogenesis in progressive liver fibrosis.

Ehling Josef J Bartneck Matthias M Wei Xiao X Gremse Felix F Fech Viktor V Möckel Diana D Baeck Christer C Hittatiya Kanishka K Eulberg Dirk D Luedde Tom T Kiessling Fabian F Trautwein Christian C Lammers Twan T Tacke Frank F

Gut 20140221 12

<h4>Objectives</h4>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.<h4>Design</h4>Angiogenesis in livers of c57BL/6 mice upon carbon tetrachlo ...[more]

PMID: 24561613

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Project description:RationaleThe initial hypertrophy response to cardiac pressure overload is considered compensatory, but with sustained stress, it eventually leads to heart failure. Recently, a role for recruited macrophages in determining the transition from compensated to decompensated hypertrophy has been established. However, whether cardiac resident immune cells influence the early phase of hypertrophy development has not been established.ObjectiveTo assess the role of cardiac immune cells in the early hypertrophy response to cardiac pressure overload induced by transverse aortic constriction (TAC).Methods and resultsWe performed cytometry by time-of-flight to determine the identity and abundance of immune cells in the heart at 1 and 4 weeks after TAC. We observed a substantial increase in cardiac macrophages 1 week after TAC. We then conducted Cite-Seq single-cell RNA sequencing of cardiac immune cells isolated from 4 sham and 6 TAC hearts. We identified 12 clusters of monocytes and macrophages, categorized as either resident or recruited macrophages, that showed remarkable changes in their abundance between sham and TAC conditions. To determine the role of cardiac resident macrophages early in the response to a hypertrophic stimulus, we used a blocking antibody against macrophage colony-stimulating factor 1 receptor (CD115). As blocking CD115 initially depletes all macrophages, we allowed the replenishment of recruited macrophages by monocytes before performing TAC. This preferential depletion of resident macrophages resulted in enhanced fibrosis and a blunted angiogenesis response to TAC. Macrophage depletion in CCR2 (C-C chemokine receptor type 2) knockout mice showed that aggravated fibrosis was primarily caused by the recruitment of monocyte-derived macrophages. Finally, 6 weeks after TAC these early events lead to depressed cardiac function and enhanced fibrosis, despite complete restoration of cardiac immune cells.ConclusionsCardiac resident macrophages are a heterogeneous population of immune cells with key roles in stimulating angiogenesis and inhibiting fibrosis in response to cardiac pressure overload.

Dataset Information

CCL2-dependent infiltrating macrophages promote angiogenesis in progressive liver fibrosis.

Publications

CCL2-dependent infiltrating macrophages promote angiogenesis in progressive liver fibrosis.

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