Impact of HDL on adipose tissue metabolism and adiponectin expression.
OBJECTIVE
The objective of the current study was to investigate the hypothesis that high-density lipoprotein (HDL) influences adipocyte metabolism and adiponectin expression. Therefore, HDL was increased in vivo via apolipoprotein (apo) A-I gene transfer and in vitro via supplementation of HDL to partly differentiated adipocytes, in the presence or absence of lipopolysaccharide (LPS), known to decrease HDL cholesterol and adiponectin levels in vivo.


RESULTS
Apo A-I transfer resulted in a significant increase of HDL cholesterol in control and LPS-injected C57BL/6 mice, which was paralleled by an increase in plasma adiponectin levels and adiponectin expression in abdominal fat. Triglyceride and free fatty acids levels after LPS administration were 2.2-fold (p<0.05) and 1.3-fold (p<0.05) lower, respectively, in Ad.hapoA-I-LPS than in Ad.Null-LPS mice. In parallel, the LPS-induced mRNA expression of hormone sensitive lipase was 3.5-fold (p=0.05) decreased in the Ad.hapoA-I-LPS group. On the other hand, apo A-I transfer abrogated the LPS-mediated reduction in lipin-1 and CD36 mRNA expression by 8.2-fold (p<0.05) and 18-fold (p<0.05), respectively. Concomitantly, the phosphorylation state of Akt was 2.0-fold (p<0.05) increased in the Ad.hapoA-I-LPS compared to the Ad.Null-LPS group. Pre-incubation of partly differentiated adipocytes with HDL (50 microg protein/ml) increased adiponectin expression by 1.5-fold under basal conditions (p<0.05) and could abrogate LPS-induced down-regulation of adiponectin, both in a phosphatidylinositol-3-kinase-dependent manner.


CONCLUSIONS
HDL affects adipocyte metabolism and adiponectin expression.
Van Linthout
Sophie
S
Charité, University-Medicine Berlin, Campus Benjamin Franklin, Department of Cardiology, Berlin, Germany.
Foryst-Ludwig
Anna
A
Spillmann
Frank
F
Peng
Jun
J
Feng
Yingmei
Y
Meloni
Marco
M
Van Craeyveld
Eline
E
Kintscher
Ulrich
U
Schultheiss
Heinz-Peter
HP
De Geest
Bart
B
Tschöpe
Carsten
C
D017667:Adipocytes / Q000166:cytology; D052242:Adiponectin / Q000096:biosynthesis* / Q000378:metabolism; D000273:Adipose Tissue / Q000473:pathology*; D000818:Animals; D016632:Apolipoprotein A-I / Q000378:metabolism; D002454:Cell Differentiation; D005786:Gene Expression Regulation; D018014:Gene Transfer Techniques; D006801:Humans; D008070:Lipopolysaccharides / Q000378:metabolism; D008075:Lipoproteins, HDL / Q000378:metabolism*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008954:Models, Biological
D052242:Adiponectin; D016632:Apolipoprotein A-I; D008070:Lipopolysaccharides; D008075:Lipoproteins, HDL