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Open Access Research

Expression of ceramide-metabolising enzymes in subcutaneous and intra-abdominal human adipose tissue

Maria Kolak1, Joanna Gertow1, Jukka Westerbacka2, Scott A Summers3, Jan Liska4, Anders Franco-Cereceda4, Matej Orešič5, Hannele Yki-Järvinen2, Per Eriksson1 and Rachel M Fisher1*

Author Affiliations

1 Atherosclerosis Research Unit, Department of Medicine (Solna), Center for Molecular Medicine, Karolinska Institutet, Stockholm, Sweden

2 Division of Diabetes, Department of Medicine, University of Helsinki, Helsinki, Finland

3 Program in Cardiovascular and Metabolic Diseases, Duke-National University of Singapore Graduate Medical School, Singapore

4 Cardiothoracic Surgery Unit, Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden

5 VTT Technical Research Centre of Finland, Espoo, Finland

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Lipids in Health and Disease 2012, 11:115  doi:10.1186/1476-511X-11-115

Published: 13 September 2012

Abstract

Background

Inflammation and increased ceramide concentrations characterise adipose tissue of obese women with high liver fat content compared to equally obese women with normal liver fat content. The present study characterises enzymes involved in ceramide metabolism in subcutaneous and intra-abdominal adipose tissue.

Methods

Pathways leading to increased ceramide concentrations in inflamed versus non-inflamed adipose tissue were investigated by quantifying expression levels of key enzymes involved in ceramide metabolism. Sphingomyelinases (sphingomyelin phosphodiesterases SMPD1-3) were investigated further using immunohistochemistry to establish their location within adipose tissue, and their mRNA expression levels were determined in subcutaneous and intra-abdominal adipose tissue from both non-obese and obese subject.

Results

Gene expression levels of sphingomyelinases, enzymes that hydrolyse sphingomyelin to ceramide, rather than enzymes involved in de novo ceramide synthesis, were higher in inflamed compared to non-inflamed adipose tissue of obese women (with high and normal liver fat contents respectively). Sphingomyelinases were localised to both macrophages and adipocytes, but also to blood vessels and to extracellular regions surrounding vessels within adipose tissue. Expression levels of SMPD3 mRNA correlated significantly with concentrations of different ceramides and sphingomyelins. In both non-obese and obese subjects SMPD3 mRNA levels were higher in the more inflamed intra-abdominal compared to the subcutaneous adipose tissue depot.

Conclusions

Generation of ceramides within adipose tissue as a result of sphingomyelinase action may contribute to inflammation in human adipose tissue.

Keywords:
Adipose tissue; Ceramide; Human; Inflammation; Sphingomyelinase