Insulin resistance in liver cirrhosis is not associated with circulating retinol-binding protein 4.
OBJECTIVE
Retinol-binding protein 4 (RBP4) has been identified as a novel adipokine mediating systemic insulin resistance, and elevated serum RBP4 indicates overt or impending insulin resistance in lean, obese, and type 2 diabetic subjects. As insulin resistance is present in nearly all patients with liver cirrhosis, we evaluated RBP4 in patients with chronic liver disease (CLD).


METHODS
Serum RBP4 was measured in 111 CLD patients. Ninety-nine age- and sex-matched healthy blood donors served as control subjects. RBP4 gene expression was also quantified in normal and cirrhotic rat liver.


RESULTS
In CLD patients, serum RBP4 was significantly reduced compared with healthy control subjects and closely correlated with the stage of liver cirrhosis. CLD patients without cirrhosis showed normal RBP4 concentrations, which correlated with serum glucose and insulin secretion and inversely correlated with insulin sensitivity. In patients with Child A-C liver cirrhosis, however, RBP4 was not correlated with glucose metabolism or other adipokines, such as adiponectin or resistin, but closely linked to the hepatic biosynthetic capacity, fibrotic changes in liver histology, or clinical complications such as portal hypertension. In an animal model of experimental cirrhosis, hepatic RBP4 gene expression decreased in cirrhotic liver.


CONCLUSIONS
RBP4 appears, unlike in obesity or type 2 diabetes, not to be a relevant systemic factor in the pathogenesis of insulin resistance in liver cirrhosis. Liver function has a tremendous impact on RBP4 levels, and future studies will need to take liver function into account when examining serum RBP4 levels.
Yagmur
Eray
E
Institute of Clinical Chemistry and Pathobiochemistry, RWTH-University Hospital Aachen, 52074 Aachen, Germany.
Weiskirchen
Ralf
R
Gressner
Axel M
AM
Trautwein
Christian
C
Tacke
Frank
F
D000328:Adult; D000368:Aged; D000818:Animals; D015415:Biomarkers / Q000097:blood; D015992:Body Mass Index; D002908:Chronic Disease; D005260:Female; D005786:Gene Expression Regulation; D006801:Humans; D007333:Insulin Resistance / Q000502:physiology*; D008103:Liver Cirrhosis / Q000145:classification / Q000503:physiopathology*; D008107:Liver Diseases / Q000097:blood*; D008297:Male; D008875:Middle Aged; D016133:Polymerase Chain Reaction; D051381:Rats; D012016:Reference Values; D012177:Retinol-Binding Proteins / Q000235:genetics* / Q000378:metabolism*; D054839:Retinol-Binding Proteins, Plasma; D044465:White People
D015415:Biomarkers; C101326:RBP4 protein, human; D012177:Retinol-Binding Proteins; D054839:Retinol-Binding Proteins, Plasma