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Clin Res Cardiol. 2016 Nov;105(11):887-900. Epub 2016 Jun 23.

Differences between perivascular adipose tissue surrounding the heart and the internal mammary artery: possible role for the leptin-inflammation-fibrosis-hypoxia axis.

Author information

1
Department of Cardiology, Democritus University of Thrace, Alexandroupolis, Greece.
2
Center for Cardiology, Department of Cardiology 1, University Medical Center of the Johannes Gutenberg University, Mainz, Germany.
3
Department of Cardiovascular Surgery, Democritus University of Thrace, Alexandroupolis, Greece.
4
Department of Pathology, Democritus University of Thrace, Alexandroupolis, Greece.
5
Laboratory of Molecular Haematology, Democritus University of Thrace, Alexandroupolis, Greece.
6
Center for Thrombosis and Hemostasis, University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany.
7
Center for Cardiology, Department of Cardiology 1, University Medical Center of the Johannes Gutenberg University, Mainz, Germany. katrin.schaefer@unimedizin-mainz.de.

Abstract

AIM:

The factors mediating the paracrine effects of perivascular adipose tissue (PVAT) in atherosclerosis are largely unknown. The adipokine leptin has been implicated in the increased cardiovascular risk in obesity and may locally promote neointima formation independently of circulating leptin levels. In patients with established coronary artery disease, we examined the expression of leptin as well as of its possible inducers in 'cardiac' PVAT surrounding the aortic root and coronary arteries (C-PVAT), and compared it to the PVAT surrounding the internal mammary artery (IMA-PVAT), a vessel resistant to atherosclerosis.

METHODS AND RESULTS:

Tissue specimens collected from male patients undergoing coronary artery bypass surgery were processed for real-time PCR, ELISA, in situ hybridization, and immunohistochemistry analysis. Leptin protein expression was elevated in C-PVAT compared to IMA-PVAT, independent of serum leptin levels. Compared to IMA-PVAT, C-PVAT exhibited more pronounced angiogenesis and inflammation, as indicated by significantly higher numbers of PECAM1-positive vessels and CD68-positive macrophages, and was characterized by a greater extent of fibrosis and hypoxia. Increased expression of hypoxia-inducible factor-1α and Fos-like antigen (FOSL)2, factors known to enhance leptin gene transcription, was observed in C-PVAT. As a proof of concept, exposure of human adipocytes to chemical hypoxia resulted in significantly increased FOSL2 and leptin mRNA levels.

CONCLUSIONS:

A higher degree of local tissue hypoxia and up-regulation of leptin expression in the perivascular adipose tissue, along with increased vascularization, inflammation, and fibrosis, may contribute to the increased atherosclerotic plaque burden in the coronary arteries compared to the IMA.

KEYWORDS:

Coronary artery disease; FOSL2; Leptin; Obesity; Perivascular adipose tissue

PMID:
27337945
DOI:
10.1007/s00392-016-0996-7
[Indexed for MEDLINE]

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